libavformat is the library containing the file format handling (mux and
-demux code for several formats). Look at ‘ffplay.c’ to use it in a
-player. See ‘libavformat/output-example.c’ to use it to generate
-audio or video streams.
-
-
You can integrate all the source code of the libraries to link them
-statically to avoid any version problem. All you need is to provide a
-’config.mak’ and a ’config.h’ in the parent directory. See the defines
-generated by ./configure to understand what is needed.
+
This document is mostly useful for internal FFmpeg developers.
+External developers who need to use the API in their application should
+refer to the API doxygen documentation in the public headers, and
+check the examples in ‘doc/examples’ and in the source code to
+see how the public API is employed.
-
You can use libavcodec or libavformat in your commercial program, but
-any patch you make must be published. The best way to proceed is
-to send your patches to the FFmpeg mailing list.
+
You can use the FFmpeg libraries in your commercial program, but you
+are encouraged to publish any patch you make. In this case the
+best way to proceed is to send your patches to the ffmpeg-devel
+mailing list following the guidelines illustrated in the remainder of
+this document.
+
+
For more detailed legal information about the use of FFmpeg in
+external programs read the ‘LICENSE’ file in the source tree and
+consult http://ffmpeg.org/legal.html.
There are the following guidelines regarding the indentation in files:
-
+
+
Indent size is 4.
+
The TAB character is forbidden outside of Makefiles as is any
form of trailing whitespace. Commits containing either will be
rejected by the git repository.
+
You should try to limit your code lines to 80 characters; however, do so if
and only if this improves readability.
@@ -188,7 +136,7 @@ and only if this improves readability.
minimize the bug count.
-
Use the JavaDoc/Doxygen format (see examples below) so that code documentation
can be generated automatically. All nontrivial functions should have a comment
above them explaining what the function does, even if it is just one sentence.
@@ -228,17 +176,21 @@ int myfunc(int my_parameter)
-
FFmpeg is programmed in the ISO C90 language with a few additional
features from ISO C99, namely:
-
+
+
the ‘inline’ keyword;
+
‘//’ comments;
+
designated struct initializers (‘struct s x = { .i = 17 };’)
+
compound literals (‘x = (struct s) { 17, 23 };’)
@@ -250,63 +202,91 @@ clarity and performance.
All code must compile with recent versions of GCC and a number of other
currently supported compilers. To ensure compatibility, please do not use
additional C99 features or GCC extensions. Especially watch out for:
-
+
+
mixing statements and declarations;
+
‘long long’ (use ‘int64_t’ instead);
+
‘__attribute__’ not protected by ‘#ifdef __GNUC__’ or similar;
+
GCC statement expressions (‘(x = ({ int y = 4; y; })’).
All names are using underscores (_), not CamelCase. For example, ‘avfilter_get_video_buffer’ is
-a valid function name and ‘AVFilterGetVideo’ is not. The exception from this are type names, like
+
All names should be composed with underscores (_), not CamelCase. For example,
+‘avfilter_get_video_buffer’ is an acceptable function name and
+‘AVFilterGetVideo’ is not. The exception from this are type names, like
for example structs and enums; they should always be in the CamelCase
-
-
There are following conventions for naming variables and functions:
-
+
There are the following conventions for naming variables and functions:
+
+
For local variables no prefix is required.
+
-For variables and functions declared as static no prefixes are required.
+For file-scope variables and functions declared as static, no prefix
+is required.
+
-For variables and functions used internally by the library, ff_ prefix
-should be used.
-For example, ‘ff_w64_demuxer’.
+For variables and functions visible outside of file scope, but only used
+internally by a library, an ff_ prefix should be used,
+e.g. ‘ff_w64_demuxer’.
+
-For variables and functions used internally across multiple libraries, use
-avpriv_. For example, ‘avpriv_aac_parse_header’.
+For variables and functions visible outside of file scope, used internally
+across multiple libraries, use avpriv_ as prefix, for example,
+‘avpriv_aac_parse_header’.
+
-For exported names, each library has its own prefixes. Just check the existing
-code and name accordingly.
+Each library has its own prefix for public symbols, in addition to the
+commonly used av_ (avformat_ for libavformat,
+avcodec_ for libavcodec, swr_ for libswresample, etc).
+Check the existing code and choose names accordingly.
+Note that some symbols without these prefixes are also exported for
+retro-compatibility reasons. These exceptions are declared in the
+lib<name>/lib<name>.v files.
Furthermore, name space reserved for the system should not be invaded.
+Identifiers ending in _t are reserved by
+POSIX.
+Also avoid names starting with __ or _ followed by an uppercase
+letter as they are reserved by the C standard. Names starting with _
+are reserved at the file level and may not be used for externally visible
+symbols. If in doubt, just avoid names starting with _ altogether.
+
In order to configure Vim to follow FFmpeg formatting conventions, paste
the following snippet into your ‘.vimrc’:
" indentation rules for FFmpeg: 4 spaces, no tabs
set expandtab
set shiftwidth=4
set softtabstop=4
-" allow tabs in Makefiles
-autocmd FileType make set noexpandtab shiftwidth=8 softtabstop=8
+set cindent
+set cinoptions=(0
+" Allow tabs in Makefiles.
+autocmd FileType make,automake set noexpandtab shiftwidth=8 softtabstop=8
" Trailing whitespace and tabs are forbidden, so highlight them.
highlight ForbiddenWhitespace ctermbg=red guibg=red
match ForbiddenWhitespace /\s\+$\|\t/
@@ -315,138 +295,178 @@ autocmd InsertEnter * match ForbiddenWhitespace /\t\|\s\+\%#\@<!$/
For Emacs, add these roughly equivalent lines to your ‘.emacs.d/init.el’:
-
- Contributions should be licensed under the LGPL 2.1, including an
- "or any later version" clause, or the MIT license. GPL 2 including
- an "or any later version" clause is also acceptable, but LGPL is
- preferred.
-
- You must not commit code which breaks FFmpeg! (Meaning unfinished but
- enabled code which breaks compilation or compiles but does not work or
- breaks the regression tests)
- You can commit unfinished stuff (for testing etc), but it must be disabled
- (#ifdef etc) by default so it does not interfere with other developers’
- work.
-
- You do not have to over-test things. If it works for you, and you think it
- should work for others, then commit. If your code has problems
- (portability, triggers compiler bugs, unusual environment etc) they will be
- reported and eventually fixed.
-
- Do not commit unrelated changes together, split them into self-contained
- pieces. Also do not forget that if part B depends on part A, but A does not
- depend on B, then A can and should be committed first and separate from B.
- Keeping changes well split into self-contained parts makes reviewing and
- understanding them on the commit log mailing list easier. This also helps
- in case of debugging later on.
- Also if you have doubts about splitting or not splitting, do not hesitate to
- ask/discuss it on the developer mailing list.
-
- Do not change behavior of the programs (renaming options etc) or public
- API or ABI without first discussing it on the ffmpeg-devel mailing list.
- Do not remove functionality from the code. Just improve!
+Contributions should be licensed under the
+LGPL 2.1,
+including an "or any later version" clause, or, if you prefer
+a gift-style license, the
+ISC or
+MIT license.
+GPL 2 including
+an "or any later version" clause is also acceptable, but LGPL is
+preferred.
+If you add a new file, give it a proper license header. Do not copy and
+paste it from a random place, use an existing file as template.
-
Note: Redundant code can be removed.
-
- Do not commit changes to the build system (Makefiles, configure script)
- which change behavior, defaults etc, without asking first. The same
- applies to compiler warning fixes, trivial looking fixes and to code
- maintained by other developers. We usually have a reason for doing things
- the way we do. Send your changes as patches to the ffmpeg-devel mailing
- list, and if the code maintainers say OK, you may commit. This does not
- apply to files you wrote and/or maintain.
- We refuse source indentation and other cosmetic changes if they are mixed
- with functional changes, such commits will be rejected and removed. Every
- developer has his own indentation style, you should not change it. Of course
- if you (re)write something, you can use your own style, even though we would
- prefer if the indentation throughout FFmpeg was consistent (Many projects
- force a given indentation style - we do not.). If you really need to make
- indentation changes (try to avoid this), separate them strictly from real
- changes.
+You must not commit code which breaks FFmpeg! (Meaning unfinished but
+enabled code which breaks compilation or compiles but does not work or
+breaks the regression tests)
+You can commit unfinished stuff (for testing etc), but it must be disabled
+(#ifdef etc) by default so it does not interfere with other developers’
+work.
-
NOTE: If you had to put if(){ .. } over a large (> 5 lines) chunk of code,
- then either do NOT change the indentation of the inner part within (do not
- move it to the right)! or do so in a separate commit
-
- Always fill out the commit log message. Describe in a few lines what you
- changed and why. You can refer to mailing list postings if you fix a
- particular bug. Comments such as "fixed!" or "Changed it." are unacceptable.
- Recommended format:
- area changed: Short 1 line description
+
+The commit message should have a short first line in the form of
+a ‘topic: short description’ as a header, separated by a newline
+from the body consisting of an explanation of why the change is necessary.
+If the commit fixes a known bug on the bug tracker, the commit message
+should include its bug ID. Referring to the issue on the bug tracker does
+not exempt you from writing an excerpt of the bug in the commit message.
-
details describing what and why and giving references.
-
- Make sure the author of the commit is set correctly. (see git commit –author)
- If you apply a patch, send an
- answer to ffmpeg-devel (or wherever you got the patch from) saying that
- you applied the patch.
- When applying patches that have been discussed (at length) on the mailing
- list, reference the thread in the log message.
+You do not have to over-test things. If it works for you, and you think it
+should work for others, then commit. If your code has problems
+(portability, triggers compiler bugs, unusual environment etc) they will be
+reported and eventually fixed.
+
- Do NOT commit to code actively maintained by others without permission.
- Send a patch to ffmpeg-devel instead. If no one answers within a reasonable
- timeframe (12h for build failures and security fixes, 3 days small changes,
- 1 week for big patches) then commit your patch if you think it is OK.
- Also note, the maintainer can simply ask for more time to review!
+Do not commit unrelated changes together, split them into self-contained
+pieces. Also do not forget that if part B depends on part A, but A does not
+depend on B, then A can and should be committed first and separate from B.
+Keeping changes well split into self-contained parts makes reviewing and
+understanding them on the commit log mailing list easier. This also helps
+in case of debugging later on.
+Also if you have doubts about splitting or not splitting, do not hesitate to
+ask/discuss it on the developer mailing list.
+
- Subscribe to the ffmpeg-cvslog mailing list. The diffs of all commits
- are sent there and reviewed by all the other developers. Bugs and possible
- improvements or general questions regarding commits are discussed there. We
- expect you to react if problems with your code are uncovered.
+Do not change behavior of the programs (renaming options etc) or public
+API or ABI without first discussing it on the ffmpeg-devel mailing list.
+Do not remove functionality from the code. Just improve!
+
+
Note: Redundant code can be removed.
+
- Update the documentation if you change behavior or add features. If you are
- unsure how best to do this, send a patch to ffmpeg-devel, the documentation
- maintainer(s) will review and commit your stuff.
+Do not commit changes to the build system (Makefiles, configure script)
+which change behavior, defaults etc, without asking first. The same
+applies to compiler warning fixes, trivial looking fixes and to code
+maintained by other developers. We usually have a reason for doing things
+the way we do. Send your changes as patches to the ffmpeg-devel mailing
+list, and if the code maintainers say OK, you may commit. This does not
+apply to files you wrote and/or maintain.
+
- Try to keep important discussions and requests (also) on the public
- developer mailing list, so that all developers can benefit from them.
+We refuse source indentation and other cosmetic changes if they are mixed
+with functional changes, such commits will be rejected and removed. Every
+developer has his own indentation style, you should not change it. Of course
+if you (re)write something, you can use your own style, even though we would
+prefer if the indentation throughout FFmpeg was consistent (Many projects
+force a given indentation style - we do not.). If you really need to make
+indentation changes (try to avoid this), separate them strictly from real
+changes.
+
+
NOTE: If you had to put if(){ .. } over a large (> 5 lines) chunk of code,
+then either do NOT change the indentation of the inner part within (do not
+move it to the right)! or do so in a separate commit
+
- Never write to unallocated memory, never write over the end of arrays,
- always check values read from some untrusted source before using them
- as array index or other risky things.
+Always fill out the commit log message. Describe in a few lines what you
+changed and why. You can refer to mailing list postings if you fix a
+particular bug. Comments such as "fixed!" or "Changed it." are unacceptable.
+Recommended format:
+area changed: Short 1 line description
+
+
details describing what and why and giving references.
+
- Remember to check if you need to bump versions for the specific libav*
- parts (libavutil, libavcodec, libavformat) you are changing. You need
- to change the version integer.
- Incrementing the first component means no backward compatibility to
- previous versions (e.g. removal of a function from the public API).
- Incrementing the second component means backward compatible change
- (e.g. addition of a function to the public API or extension of an
- existing data structure).
- Incrementing the third component means a noteworthy binary compatible
- change (e.g. encoder bug fix that matters for the decoder).
+Make sure the author of the commit is set correctly. (see git commit –author)
+If you apply a patch, send an
+answer to ffmpeg-devel (or wherever you got the patch from) saying that
+you applied the patch.
+
- Compiler warnings indicate potential bugs or code with bad style. If a type of
- warning always points to correct and clean code, that warning should
- be disabled, not the code changed.
- Thus the remaining warnings can either be bugs or correct code.
- If it is a bug, the bug has to be fixed. If it is not, the code should
- be changed to not generate a warning unless that causes a slowdown
- or obfuscates the code.
+When applying patches that have been discussed (at length) on the mailing
+list, reference the thread in the log message.
+
- If you add a new file, give it a proper license header. Do not copy and
- paste it from a random place, use an existing file as template.
+Do NOT commit to code actively maintained by others without permission.
+Send a patch to ffmpeg-devel instead. If no one answers within a reasonable
+timeframe (12h for build failures and security fixes, 3 days small changes,
+1 week for big patches) then commit your patch if you think it is OK.
+Also note, the maintainer can simply ask for more time to review!
+
+
+Subscribe to the ffmpeg-cvslog mailing list. The diffs of all commits
+are sent there and reviewed by all the other developers. Bugs and possible
+improvements or general questions regarding commits are discussed there. We
+expect you to react if problems with your code are uncovered.
+
+
+Update the documentation if you change behavior or add features. If you are
+unsure how best to do this, send a patch to ffmpeg-devel, the documentation
+maintainer(s) will review and commit your stuff.
+
+
+Try to keep important discussions and requests (also) on the public
+developer mailing list, so that all developers can benefit from them.
+
+
+Never write to unallocated memory, never write over the end of arrays,
+always check values read from some untrusted source before using them
+as array index or other risky things.
+
+
+Remember to check if you need to bump versions for the specific libav*
+parts (libavutil, libavcodec, libavformat) you are changing. You need
+to change the version integer.
+Incrementing the first component means no backward compatibility to
+previous versions (e.g. removal of a function from the public API).
+Incrementing the second component means backward compatible change
+(e.g. addition of a function to the public API or extension of an
+existing data structure).
+Incrementing the third component means a noteworthy binary compatible
+change (e.g. encoder bug fix that matters for the decoder). The third
+component always starts at 100 to distinguish FFmpeg from Libav.
+
+
+Compiler warnings indicate potential bugs or code with bad style. If a type of
+warning always points to correct and clean code, that warning should
+be disabled, not the code changed.
+Thus the remaining warnings can either be bugs or correct code.
+If it is a bug, the bug has to be fixed. If it is not, the code should
+be changed to not generate a warning unless that causes a slowdown
+or obfuscates the code.
+
+
+Make sure that no parts of the codebase that you maintain are missing from the
+‘MAINTAINERS’ file. If something that you want to maintain is missing add it with
+your name after it.
+If at some point you no longer want to maintain some code, then please help
+finding a new maintainer and also don’t forget updating the ‘MAINTAINERS’ file.
We think our rules are not too hard. If you have comments, contact us.
-
Note, these rules are mostly borrowed from the MPlayer project.
-
First, read the Coding Rules above if you did not yet, in particular
the rules regarding patch submission.
@@ -467,11 +487,6 @@ The tool is located in the tools directory.
Run the Regression tests before submitting a patch in order to verify
it does not cause unexpected problems.
-
Patches should be posted as base64 encoded attachments (or any other
-encoding which ensures that the patch will not be trashed during
-transmission) to the ffmpeg-devel mailing list, see
-http://lists.ffmpeg.org/mailman/listinfo/ffmpeg-devel
-
It also helps quite a bit if you tell us what the patch does (for example
’replaces lrint by lrintf’), and why (for example ’*BSD isn’t C99 compliant
and has no lrint()’)
@@ -479,6 +494,13 @@ and has no lrint()’)
Also please if you send several patches, send each patch as a separate mail,
do not attach several unrelated patches to the same mail.
+
Patches should be posted to the
+ffmpeg-devel
+mailing list. Use git send-email when possible since it will properly
+send patches without requiring extra care. If you cannot, then send patches
+as base64-encoded attachments, so your patch is not trashed during
+transmission.
+
Your patch will be reviewed on the mailing list. You will likely be asked
to make some changes and are expected to send in an improved version that
incorporates the requests from the review. This process may go through
@@ -490,121 +512,170 @@ send a reminder by email. Your patch should eventually be dealt with.
- Did you use av_cold for codec initialization and close functions?
+Did you use av_cold for codec initialization and close functions?
+
- Did you add a long_name under NULL_IF_CONFIG_SMALL to the AVCodec or
- AVInputFormat/AVOutputFormat struct?
+Did you add a long_name under NULL_IF_CONFIG_SMALL to the AVCodec or
+AVInputFormat/AVOutputFormat struct?
+
- Did you bump the minor version number (and reset the micro version
- number) in ‘libavcodec/version.h’ or ‘libavformat/version.h’?
+Did you bump the minor version number (and reset the micro version
+number) in ‘libavcodec/version.h’ or ‘libavformat/version.h’?
+
- Did you register it in ‘allcodecs.c’ or ‘allformats.c’?
+Did you register it in ‘allcodecs.c’ or ‘allformats.c’?
+
- Did you add the CodecID to ‘avcodec.h’?
+Did you add the AVCodecID to ‘avcodec.h’?
+When adding new codec IDs, also add an entry to the codec descriptor
+list in ‘libavcodec/codec_desc.c’.
+
- If it has a fourCC, did you add it to ‘libavformat/riff.c’,
- even if it is only a decoder?
+If it has a FourCC, did you add it to ‘libavformat/riff.c’,
+even if it is only a decoder?
+
- Did you add a rule to compile the appropriate files in the Makefile?
- Remember to do this even if you’re just adding a format to a file that is
- already being compiled by some other rule, like a raw demuxer.
+Did you add a rule to compile the appropriate files in the Makefile?
+Remember to do this even if you’re just adding a format to a file that is
+already being compiled by some other rule, like a raw demuxer.
+
- Did you add an entry to the table of supported formats or codecs in
- ‘doc/general.texi’?
+Did you add an entry to the table of supported formats or codecs in
+‘doc/general.texi’?
+
- Did you add an entry in the Changelog?
+Did you add an entry in the Changelog?
+
- If it depends on a parser or a library, did you add that dependency in
- configure?
+If it depends on a parser or a library, did you add that dependency in
+configure?
+
- Did you git add the appropriate files before committing?
+Did you git add the appropriate files before committing?
+
- Did you make sure it compiles standalone, i.e. with
- configure --disable-everything --enable-decoder=foo
- (or --enable-demuxer or whatever your component is)?
+Did you make sure it compiles standalone, i.e. with
+configure --disable-everything --enable-decoder=foo
+(or --enable-demuxer or whatever your component is)?
- Did you provide a clear git commit log message?
+Did you provide a clear git commit log message?
+
- Is the patch against latest FFmpeg git master branch?
+Is the patch against latest FFmpeg git master branch?
+
- Are you subscribed to ffmpeg-devel?
- (the list is subscribers only due to spam)
+Are you subscribed to ffmpeg-devel?
+(the list is subscribers only due to spam)
+
- Have you checked that the changes are minimal, so that the same cannot be
- achieved with a smaller patch and/or simpler final code?
+Have you checked that the changes are minimal, so that the same cannot be
+achieved with a smaller patch and/or simpler final code?
+
- If the change is to speed critical code, did you benchmark it?
+If the change is to speed critical code, did you benchmark it?
+
- If you did any benchmarks, did you provide them in the mail?
+If you did any benchmarks, did you provide them in the mail?
+
- Have you checked that the patch does not introduce buffer overflows or
- other security issues?
+Have you checked that the patch does not introduce buffer overflows or
+other security issues?
+
- Did you test your decoder or demuxer against damaged data? If no, see
- tools/trasher and the noise bitstream filter. Your decoder or demuxer
- should not crash or end in a (near) infinite loop when fed damaged data.
+Did you test your decoder or demuxer against damaged data? If no, see
+tools/trasher, the noise bitstream filter, and
+zzuf. Your decoder or demuxer
+should not crash, end in a (near) infinite loop, or allocate ridiculous
+amounts of memory when fed damaged data.
+
- Does the patch not mix functional and cosmetic changes?
+Does the patch not mix functional and cosmetic changes?
+
- Did you add tabs or trailing whitespace to the code? Both are forbidden.
+Did you add tabs or trailing whitespace to the code? Both are forbidden.
+
- Is the patch attached to the email you send?
+Is the patch attached to the email you send?
+
- Is the mime type of the patch correct? It should be text/x-diff or
- text/x-patch or at least text/plain and not application/octet-stream.
+Is the mime type of the patch correct? It should be text/x-diff or
+text/x-patch or at least text/plain and not application/octet-stream.
+
- If the patch fixes a bug, did you provide a verbose analysis of the bug?
+If the patch fixes a bug, did you provide a verbose analysis of the bug?
+
- If the patch fixes a bug, did you provide enough information, including
- a sample, so the bug can be reproduced and the fix can be verified?
- Note please do not attach samples >100k to mails but rather provide a
- URL, you can upload to ftp://upload.ffmpeg.org
+If the patch fixes a bug, did you provide enough information, including
+a sample, so the bug can be reproduced and the fix can be verified?
+Note please do not attach samples >100k to mails but rather provide a
+URL, you can upload to ftp://upload.ffmpeg.org
+
- Did you provide a verbose summary about what the patch does change?
+Did you provide a verbose summary about what the patch does change?
+
- Did you provide a verbose explanation why it changes things like it does?
+Did you provide a verbose explanation why it changes things like it does?
+
- Did you provide a verbose summary of the user visible advantages and
- disadvantages if the patch is applied?
+Did you provide a verbose summary of the user visible advantages and
+disadvantages if the patch is applied?
+
- Did you provide an example so we can verify the new feature added by the
- patch easily?
+Did you provide an example so we can verify the new feature added by the
+patch easily?
+
- If you added a new file, did you insert a license header? It should be
- taken from FFmpeg, not randomly copied and pasted from somewhere else.
+If you added a new file, did you insert a license header? It should be
+taken from FFmpeg, not randomly copied and pasted from somewhere else.
+
- You should maintain alphabetical order in alphabetically ordered lists as
- long as doing so does not break API/ABI compatibility.
+You should maintain alphabetical order in alphabetically ordered lists as
+long as doing so does not break API/ABI compatibility.
+
- Lines with similar content should be aligned vertically when doing so
- improves readability.
+Lines with similar content should be aligned vertically when doing so
+improves readability.
+
- Consider to add a regression test for your code.
+Consider to add a regression test for your code.
+
- If you added YASM code please check that things still work with –disable-yasm
+If you added YASM code please check that things still work with –disable-yasm
+
+
+Make sure you check the return values of function and return appropriate
+error codes. Especially memory allocation functions like av_malloc()
+are notoriously left unchecked, which is a serious problem.
+
+
+Test your code with valgrind and or Address Sanitizer to ensure it’s free
+of leaks, out of array accesses, etc.
All patches posted to ffmpeg-devel will be reviewed, unless they contain a
clear note that the patch is not for the git master branch.
@@ -632,7 +703,7 @@ separate patches.
Before submitting a patch (or committing to the repository), you should at least
test that you did not break anything.
@@ -643,14 +714,164 @@ test that you did not break anything.
this case, the reference results of the regression tests shall be modified
accordingly].
When there is no muxer or encoder available to generate test media for a
+specific test then the media has to be inlcuded in the fate-suite.
+First please make sure that the sample file is as small as possible to test the
+respective decoder or demuxer sufficiently. Large files increase network
+bandwidth and disk space requirements.
+Once you have a working fate test and fate sample, provide in the commit
+message or introductionary message for the patch series that you post to
+the ffmpeg-devel mailing list, a direct link to download the sample media.
The FFmpeg build system allows visualizing the test coverage in an easy
+manner with the coverage tools gcov/lcov. This involves
+the following steps:
+
+
+
+ Configure to compile with instrumentation enabled:
+ configure --toolchain=gcov.
+
+
+ Run your test case, either manually or via FATE. This can be either
+ the full FATE regression suite, or any arbitrary invocation of any
+ front-end tool provided by FFmpeg, in any combination.
+
+
+ Run make lcov to generate coverage data in HTML format.
+
+
+ View lcov/index.html in your preferred HTML viewer.
+
+
+
You can use the command make lcov-reset to reset the coverage
+measurements. You will need to rerun make lcov after running a
+new test.
+
The configure script provides a shortcut for using valgrind to spot bugs
+related to memory handling. Just add the option
+--toolchain=valgrind-memcheck or --toolchain=valgrind-massif
+to your configure line, and reasonable defaults will be set for running
+FATE under the supervision of either the memcheck or the
+massif tool of the valgrind suite.
+
+
In case you need finer control over how valgrind is invoked, use the
+--target-exec='valgrind <your_custom_valgrind_options> option in
+your configure line instead.
+
FFmpeg maintains a set of release branches, which are the
+recommended deliverable for system integrators and distributors (such as
+Linux distributions, etc.). At regular times, a release
+manager prepares, tests and publishes tarballs on the
+http://ffmpeg.org website.
+
+
There are two kinds of releases:
+
+
+
+Major releases always include the latest and greatest
+features and functionality.
+
+
+Point releases are cut from release branches,
+which are named release/X, with X being the release
+version number.
+
+
+
Note that we promise to our users that shared libraries from any FFmpeg
+release never break programs that have been compiled against
+previous versions of the same release series in any case!
+
+
However, from time to time, we do make API changes that require adaptations
+in applications. Such changes are only allowed in (new) major releases and
+require further steps such as bumping library version numbers and/or
+adjustments to the symbol versioning file. Please discuss such changes
+on the ffmpeg-devel mailing list in time to allow forward planning.
+
@@ -231,6 +181,18 @@ not a bug they should fix:
Then again, some of them do not know the difference between an undecidable
problem and an NP-hard problem...
+
+
Distributions usually split libraries in several packages. The main package
+contains the files necessary to run programs using the library. The
+development package contains the files necessary to build programs using the
+library. Sometimes, docs and/or data are in a separate package too.
+
+
To build FFmpeg, you need to install the development package. It is usually
+called ‘libfoo-dev’ or ‘libfoo-devel’. You can remove it after the
+build is finished, but be sure to keep the main package.
+
@@ -248,20 +210,28 @@ If this does not help see
For example, img1.jpg, img2.jpg, img3.jpg,...
Then you may run:
-
ffmpeg -f image2 -i img%d.jpg /tmp/a.mpg
+
ffmpeg -f image2 -i img%d.jpg /tmp/a.mpg
Notice that ‘%d’ is replaced by the image number.
-
‘img%03d.jpg’ means the sequence ‘img001.jpg’, ‘img002.jpg’, etc...
+
‘img%03d.jpg’ means the sequence ‘img001.jpg’, ‘img002.jpg’, etc.
+
Use the ‘-start_number’ option to declare a starting number for
+the sequence. This is useful if your sequence does not start with
+‘img001.jpg’ but is still in a numerical order. The following
+example will start with ‘img100.jpg’:
+
If you have large number of pictures to rename, you can use the
following command to ease the burden. The command, using the bourne
shell syntax, symbolically links all files in the current directory
that match *jpg to the ‘/tmp’ directory in the sequence of
‘img001.jpg’, ‘img002.jpg’ and so on.
-
x=1; for i in *jpg; do counter=$(printf %03d $x); ln -s "$i" /tmp/img"$counter".jpg; x=$(($x+1)); done
+
x=1; for i in *jpg; do counter=$(printf %03d $x); ln -s "$i" /tmp/img"$counter".jpg; x=$(($x+1)); done
If you want to sequence them by oldest modified first, substitute
@@ -269,17 +239,22 @@ that match *jpg to the ‘/tmp’ directory in the
Then run:
-
ffmpeg -f image2 -i /tmp/img%03d.jpg /tmp/a.mpg
+
ffmpeg -f image2 -i /tmp/img%03d.jpg /tmp/a.mpg
The same logic is used for any image format that ffmpeg reads.
Beware that there is no "jpeg" codec. Use "mjpeg" instead.
@@ -360,47 +335,116 @@ material, and try ’-top 0/1’ if the result looks really messed-up.
then you may use any file that DirectShow can read as input.
Just create an "input.avs" text file with this single line ...
-
DirectShowSource("C:\path to your file\yourfile.asf")
+
DirectShowSource("C:\path to your file\yourfile.asf")
... and then feed that text file to ffmpeg:
-
ffmpeg -i input.avs
+
ffmpeg -i input.avs
-
For ANY other help on Avisynth, please visit the
-Avisynth homepage.
+
For ANY other help on AviSynth, please visit the
+AviSynth homepage.
A few multimedia containers (MPEG-1, MPEG-2 PS, DV) allow to join video files by
-merely concatenating them.
+
To "join" video files is quite ambiguous. The following list explains the
+different kinds of "joining" and points out how those are addressed in
+FFmpeg. To join video files may mean:
+
+
+
+To put them one after the other: this is called to concatenate them
+(in short: concat) and is addressed
+in this very faq.
+
+
+To put them together in the same file, to let the user choose between the
+different versions (example: different audio languages): this is called to
+multiplex them together (in short: mux), and is done by simply
+invoking ffmpeg with several ‘-i’ options.
+
+
+For audio, to put all channels together in a single stream (example: two
+mono streams into one stereo stream): this is sometimes called to
+merge them, and can be done using the
+amerge filter.
+
+
+For audio, to play one on top of the other: this is called to mix
+them, and can be done by first merging them into a single stream and then
+using the pan filter to mix
+the channels at will.
+
+
+For video, to display both together, side by side or one on top of a part of
+the other; it can be done using the
+overlay video filter.
+
+
FFmpeg has a concat filter designed specifically for that, with examples in the
+documentation. This operation is recommended if you need to re-encode.
+
FFmpeg has a concat protocol designed specifically for that, with examples in the
+documentation.
+
+
A few multimedia containers (MPEG-1, MPEG-2 PS, DV) allow to concatenate
+video by merely concatenating the files containing them.
Hence you may concatenate your multimedia files by first transcoding them to
these privileged formats, then using the humble cat command (or the
equally humble copy under Windows), and finally transcoding back to your
format of choice.
Notice that you should either use -same_quant or set a reasonably high
-bitrate for your intermediate and output files, if you want to preserve
-video quality.
+
Additionally, you can use the concat protocol instead of cat or
+copy which will avoid creation of a potentially huge intermediate file.
-
Also notice that you may avoid the huge intermediate files by taking advantage
-of named pipes, should your platform support it:
+
Similarly, the yuv4mpegpipe format, and the raw video, raw audio codecs also
allow concatenation, and the transcoding step is almost lossless.
When using multiple yuv4mpegpipe(s), the first line needs to be discarded
@@ -408,7 +452,8 @@ from all but the first stream. This can be accomplished by piping through
tail as seen below. Note that when piping through tail you
must use command grouping, { ;}, to background properly.
-
For example, let’s say we want to join two FLV files into an output.flv file:
+
For example, let’s say we want to concatenate two FLV files into an
+output.flv file:
VOB and a few other formats do not have a global header that describes
+everything present in the file. Instead, applications are supposed to scan
+the file to see what it contains. Since VOB files are frequently large, only
+the beginning is scanned. If the subtitles happen only later in the file,
+they will not be initally detected.
+
+
Some applications, including the ffmpeg command-line tool, can only
+work with streams that were detected during the initial scan; streams that
+are detected later are ignored.
+
+
The size of the initial scan is controlled by two options: probesize
+(default ~5 Mo) and analyzeduration (default 5,000,000 µs = 5 s). For
+the subtitle stream to be detected, both values must be large enough.
+
The ‘-sameq’ option meant "same quantizer", and made sense only in a
+very limited set of cases. Unfortunately, a lot of people mistook it for
+"same quality" and used it in places where it did not make sense: it had
+roughly the expected visible effect, but achieved it in a very inefficient
+way.
+
+
Each encoder has its own set of options to set the quality-vs-size balance,
+use the options for the encoder you are using to set the quality level to a
+point acceptable for your tastes. The most common options to do that are
+‘-qscale’ and ‘-qmax’, but you should peruse the documentation
+of the encoder you chose.
+
Examples are also installed by default, usually in
+$PREFIX/share/ffmpeg/examples.
+
+
Also you may read the Developers Guide of the FFmpeg documentation. Alternatively,
examine the source code for one of the many open source projects that
already incorporate FFmpeg at (projects.html).
@@ -486,40 +570,16 @@ with #ifdefs related to the compiler.
No. Microsoft Visual C++ is not compliant to the C99 standard and does
-not - among other things - support the inline assembly used in FFmpeg.
-If you wish to use MSVC++ for your
-project then you can link the MSVC++ code with libav* as long as
-you compile the latter with a working C compiler. For more information, see
-the Microsoft Visual C++ compatibility section in the FFmpeg
-documentation.
-
-
There have been efforts to make FFmpeg compatible with MSVC++ in the
-past. However, they have all been rejected as too intrusive, especially
-since MinGW does the job adequately. None of the core developers
-work with MSVC++ and thus this item is low priority. Should you find
-the silver bullet that solves this problem, feel free to shoot it at us.
-
-
We strongly recommend you to move over from MSVC++ to MinGW tools.
-
FFmpeg is already organized in a highly modular manner and does not need to
be rewritten in a formal object language. Further, many of the developers
@@ -527,19 +587,38 @@ favor straight C; it works for them. For more arguments on this matter,
read "Programming Religion".
The build process creates ffmpeg_g, ffplay_g, etc. which contain full debug
-information. Those binaries are stripped to create ffmpeg, ffplay, etc. If
-you need the debug information, use the *_g versions.
+
The build process creates ffmpeg_g, ffplay_g, etc. which
+contain full debug information. Those binaries are stripped to create
+ffmpeg, ffplay, etc. If you need the debug information, use
+the *_g versions.
Yes, as long as the code is optional and can easily and cleanly be placed
under #if CONFIG_GPL without breaking anything. So, for example, a new codec
or filter would be OK under GPL while a bug fix to LGPL code would not.
FFmpeg builds static libraries by default. In static libraries, dependencies
+are not handled. That has two consequences. First, you must specify the
+libraries in dependency order: -lavdevice must come before
+-lavformat, -lavutil must come after everything else, etc.
+Second, external libraries that are used in FFmpeg have to be specified too.
+
+
An easy way to get the full list of required libraries in dependency order
+is to use pkg-config.
+
+
c99 -o program program.c $(pkg-config --cflags --libs libavformat libavcodec)
+
+
+
See ‘doc/example/Makefile’ and ‘doc/example/pc-uninstalled’ for
+more details.
+
You have to create a custom AVIOContext using avio_alloc_context,
+see ‘libavformat/aviobuf.c’ in FFmpeg and ‘libmpdemux/demux_lavf.c’ in MPlayer or MPlayer2 sources.
Even if peculiar since it is network oriented, RTP is a container like any
other. You have to demux RTP before feeding the payload to libavcodec.
In this specific case please look at RFC 4629 to see how it should be done.
r_frame_rate is NOT the average frame rate, it is the smallest frame rate
+
r_frame_rate is NOT the average frame rate, it is the smallest frame rate
that can accurately represent all timestamps. So no, it is not
wrong if it is larger than the average!
-For example, if you have mixed 25 and 30 fps content, then r_frame_rate
-will be 150.
+For example, if you have mixed 25 and 30 fps content, then r_frame_rate
+will be 150 (it is the least common multiple).
+If you are looking for the average frame rate, see AVStream.avg_frame_rate.
Make sure you have the fate-suite samples and the SAMPLES Make variable
or FATE_SAMPLES environment variable or the --samplesconfigure option is set to the right path.
Do you happen to have a ~ character in the samples path to indicate a
home directory? The value is used in ways where the shell cannot expand it,
causing FATE to not find files. Just replace ~ by the full path.
This is especially recommended for all people contributing source
code to FFmpeg, as it can be seen if some test on some platform broke
-with there recent contribution. This usually happens on the platforms
+with their recent contribution. This usually happens on the platforms
the developers could not test on.
The second part of this document describes how you can run FATE to
@@ -168,23 +110,26 @@ it in your interactive session.
FATE_SAMPLES=fate-suite/ make fate
-
+
Do not put a ’~’ character in the samples path to indicate a home
directory. Because of shell nuances, this will cause FATE to fail.
+
To use a custom wrapper to run the test, pass ‘--target-exec’ to
+configure or set the TARGET_EXEC Make variable.
+
To submit your results to the server you should run fate through the
-shell script tests/fate.sh from the FFmpeg sources. This script needs
+shell script ‘tests/fate.sh’ from the FFmpeg sources. This script needs
to be invoked with a configuration file as its first argument.
tests/fate.sh /path/to/fate_config
A configuration file template with comments describing the individual
-configuration variables can be found at ‘tests/fate_config.sh.template’.
+configuration variables can be found at ‘doc/fate_config.sh.template’.
The mentioned configuration template is also available here:
slot= # some unique identifier
@@ -193,16 +138,20 @@ samples= # path to samples directory
workdir= # directory in which to do all the work
#fate_recv="ssh -T fate@fate.ffmpeg.org" # command to submit report
comment= # optional description
+build_only= # set to "yes" for a compile-only instance that skips tests
# the following are optional and map to configure options
arch=
cpu=
cross_prefix=
+as=
cc=
+ld=
target_os=
sysroot=
target_exec=
target_path=
+target_samples=
extra_cflags=
extra_ldflags=
extra_libs=
@@ -234,8 +183,9 @@ present in $workdir as specified in the configuration file:
version
-
When you have everything working properly you can create an SSH key and
-send its public part to the FATE server administrator.
+
When you have everything working properly you can create an SSH key pair
+and send the public key to the FATE server administrator who can be contacted
+at the email address fate-admin@ffmpeg.org.
Configure your SSH client to use public key authentication with that key
when connecting to the FATE server. Also do not forget to check the identity
@@ -243,7 +193,19 @@ of the server and to accept its host key. This can usually be achieved by
running your SSH client manually and killing it after you accepted the key.
The FATE server’s fingerprint is:
-
b1:31:c8:79:3f:04:1d:f8:f2:23:26:5a:fd:55:fa:92
+
+
‘RSA’
+
d3:f1:83:97:a4:75:2b:a6:fb:d6:e8:aa:81:93:97:51
+
+
‘ECDSA’
+
76:9f:68:32:04:1e:d5:d4:ec:47:3f:dc:fc:18:17:86
+
+
+
+
If you have problems connecting to the FATE server, it may help to try out
+the ssh command with one or more ‘-v’ options. You should
+get detailed output concerning your SSH configuration and the authentication
+process.
The only thing left is to automate the execution of the fate.sh script and
the synchronisation of the samples directory.
@@ -257,15 +219,15 @@ the synchronisation of the samples directory.
‘fate-rsync’
-
Download/synchronize sample files to the configured samples directory.
+
Download/synchronize sample files to the configured samples directory.
‘fate-list’
-
Will list all fate/regression test targets.
+
Will list all fate/regression test targets.
‘fate’
-
Run the FATE test suite (requires the fate-suite dataset).
+
Run the FATE test suite (requires the fate-suite dataset).
@@ -274,7 +236,7 @@ the synchronisation of the samples directory.
‘V’
-
Verbosity level, can be set to 0, 1 or 2.
+
Verbosity level, can be set to 0, 1 or 2.
0: show just the test arguments
1: show just the command used in the test
@@ -283,27 +245,40 @@ the synchronisation of the samples directory.
‘SAMPLES’
-
Specify or override the path to the FATE samples at make time, it has a
- meaning only while running the regression tests.
+
Specify or override the path to the FATE samples at make time, it has a
+meaning only while running the regression tests.
‘THREADS’
-
Specify how many threads to use while running regression tests, it is
- quite useful to detect thread-related regressions.
+
Specify how many threads to use while running regression tests, it is
+quite useful to detect thread-related regressions.
+
+
+
‘THREAD_TYPE’
+
Specify which threading strategy test, either slice or frame,
+by default slice+frame
+
+
+
‘CPUFLAGS’
+
Specify CPU flags.
+
+
+
‘TARGET_EXEC’
+
Specify or override the wrapper used to run the tests.
+The TARGET_EXEC option provides a way to run FATE wrapped in
+valgrind, qemu-user or wine or on remote targets
+through ssh.
+
+
+
‘GEN’
+
Set to 1 to generate the missing or mismatched references.
-
Example:
-
make V=1 SAMPLES=/var/fate/samples THREADS=2 fate
+
+
ffmpeg is a very fast video and audio converter that can also grab from
+
ffmpeg is a very fast video and audio converter that can also grab from
a live audio/video source. It can also convert between arbitrary sample
rates and resize video on the fly with a high quality polyphase filter.
-
ffmpeg reads from an arbitrary number of input "files" (which can be regular
+
ffmpeg reads from an arbitrary number of input "files" (which can be regular
files, pipes, network streams, grabbing devices, etc.), specified by the
-i option, and writes to an arbitrary number of output "files", which are
specified by a plain output filename. Anything found on the command line which
cannot be interpreted as an option is considered to be an output filename.
-
Each input or output file can in principle contain any number of streams of
-different types (video/audio/subtitle/attachment/data). Allowed number and/or
-types of streams can be limited by the container format. Selecting, which
-streams from which inputs go into output, is done either automatically or with
-the -map option (see the Stream selection chapter).
+
Each input or output file can, in principle, contain any number of streams of
+different types (video/audio/subtitle/attachment/data). The allowed number and/or
+types of streams may be limited by the container format. Selecting which
+streams from which inputs will go into which output is either done automatically
+or with the -map option (see the Stream selection chapter).
To refer to input files in options, you must use their indices (0-based). E.g.
-the first input file is 0, the second is 1 etc. Similarly, streams
+the first input file is 0, the second is 1, etc. Similarly, streams
within a file are referred to by their indices. E.g. 2:3 refers to the
-fourth stream in the third input file. See also the Stream specifiers chapter.
+fourth stream in the third input file. Also see the Stream specifiers chapter.
As a general rule, options are applied to the next specified
file. Therefore, order is important, and you can have the same
@@ -440,8 +116,8 @@ options apply ONLY to the next input or output file and are reset between files.
-To set the video bitrate of the output file to 64kbit/s:
-
ffmpeg -i input.avi -b:v 64k output.avi
+To set the video bitrate of the output file to 64 kbit/s:
+
By default ffmpeg includes only one stream of each type (video, audio, subtitle)
-present in the input files and adds them to each output file. It picks the
-"best" of each based upon the following criteria; for video it is the stream
-with the highest resolution, for audio the stream with the most channels, for
-subtitle it’s the first subtitle stream. In the case where several streams of
-the same type rate equally, the lowest numbered stream is chosen.
+
The transcoding process in ffmpeg for each output can be described by
+the following diagram:
-
You can disable some of those defaults by using -vn/-an/-sn options. For
+
ffmpeg calls the libavformat library (containing demuxers) to read
+input files and get packets containing encoded data from them. When there are
+multiple input files, ffmpeg tries to keep them synchronized by
+tracking lowest timestamp on any active input stream.
+
+
Encoded packets are then passed to the decoder (unless streamcopy is selected
+for the stream, see further for a description). The decoder produces
+uncompressed frames (raw video/PCM audio/...) which can be processed further by
+filtering (see next section). After filtering, the frames are passed to the
+encoder, which encodes them and outputs encoded packets. Finally those are
+passed to the muxer, which writes the encoded packets to the output file.
+
Before encoding, ffmpeg can process raw audio and video frames using
+filters from the libavfilter library. Several chained filters form a filter
+graph. ffmpeg distinguishes between two types of filtergraphs:
+simple and complex.
+
Simple filtergraphs are those that have exactly one input and output, both of
+the same type. In the above diagram they can be represented by simply inserting
+an additional step between decoding and encoding:
+
Simple filtergraphs are configured with the per-stream ‘-filter’ option
+(with ‘-vf’ and ‘-af’ aliases for video and audio respectively).
+A simple filtergraph for video can look for example like this:
+
Note that some filters change frame properties but not frame contents. E.g. the
+fps filter in the example above changes number of frames, but does not
+touch the frame contents. Another example is the setpts filter, which
+only sets timestamps and otherwise passes the frames unchanged.
+
Complex filtergraphs are those which cannot be described as simply a linear
+processing chain applied to one stream. This is the case, for example, when the graph has
+more than one input and/or output, or when output stream type is different from
+input. They can be represented with the following diagram:
+
Complex filtergraphs are configured with the ‘-filter_complex’ option.
+Note that this option is global, since a complex filtergraph, by its nature,
+cannot be unambiguously associated with a single stream or file.
+
+
The ‘-lavfi’ option is equivalent to ‘-filter_complex’.
+
+
A trivial example of a complex filtergraph is the overlay filter, which
+has two video inputs and one video output, containing one video overlaid on top
+of the other. Its audio counterpart is the amix filter.
+
Stream copy is a mode selected by supplying the copy parameter to the
+‘-codec’ option. It makes ffmpeg omit the decoding and encoding
+step for the specified stream, so it does only demuxing and muxing. It is useful
+for changing the container format or modifying container-level metadata. The
+diagram above will, in this case, simplify to this:
+
Since there is no decoding or encoding, it is very fast and there is no quality
+loss. However, it might not work in some cases because of many factors. Applying
+filters is obviously also impossible, since filters work on uncompressed data.
+
By default, ffmpeg includes only one stream of each type (video, audio, subtitle)
+present in the input files and adds them to each output file. It picks the
+"best" of each based upon the following criteria: for video, it is the stream
+with the highest resolution, for audio, it is the stream with the most channels, for
+subtitles, it is the first subtitle stream. In the case where several streams of
+the same type rate equally, the stream with the lowest index is chosen.
+
+
You can disable some of those defaults by using the -vn/-an/-sn options. For
full manual control, use the -map option, which disables the defaults just
described.
All the numerical options, if not specified otherwise, accept in input
-a string representing a number, which may contain one of the
-International System number postfixes, for example ’K’, ’M’, ’G’.
-If ’i’ is appended after the postfix, powers of 2 are used instead of
-powers of 10. The ’B’ postfix multiplies the value for 8, and can be
-appended after another postfix or used alone. This allows using for
-example ’KB’, ’MiB’, ’G’ and ’B’ as postfix.
+
All the numerical options, if not specified otherwise, accept a string
+representing a number as input, which may be followed by one of the SI
+unit prefixes, for example: ’K’, ’M’, or ’G’.
+
+
If ’i’ is appended to the SI unit prefix, the complete prefix will be
+interpreted as a unit prefix for binary multiplies, which are based on
+powers of 1024 instead of powers of 1000. Appending ’B’ to the SI unit
+prefix multiplies the value by 8. This allows using, for example:
+’KB’, ’MiB’, ’G’ and ’B’ as number suffixes.
Options which do not take arguments are boolean options, and set the
corresponding value to true. They can be set to false by prefixing
-with "no" the option name, for example using "-nofoo" in the
-command line will set to false the boolean option with name "foo".
+the option name with "no". For example using "-nofoo"
+will set the boolean option with name "foo" to false.
Some options are applied per-stream, e.g. bitrate or codec. Stream specifiers
-are used to precisely specify which stream(s) does a given option belong to.
+are used to precisely specify which stream(s) a given option belongs to.
A stream specifier is a string generally appended to the option name and
-separated from it by a colon. E.g. -codec:a:1 ac3 option contains
-a:1 stream specifer, which matches the second audio stream. Therefore it
+separated from it by a colon. E.g. -codec:a:1 ac3 contains the
+a:1 stream specifier, which matches the second audio stream. Therefore, it
would select the ac3 codec for the second audio stream.
-
A stream specifier can match several stream, the option is then applied to all
+
A stream specifier can match several streams, so that the option is applied to all
of them. E.g. the stream specifier in -b:a 128k matches all audio
streams.
-
An empty stream specifier matches all streams, for example -codec copy
+
An empty stream specifier matches all streams. For example, -codec copy
or -codec: copy would copy all the streams without reencoding.
Possible forms of stream specifiers are:
@@ -515,29 +313,73 @@ or -codec: copy would copy all the streams without reencoding.
thread count for the second stream to 4.
‘stream_type[:stream_index]’
-
stream_type is one of: ’v’ for video, ’a’ for audio, ’s’ for subtitle,
-’d’ for data and ’t’ for attachments. If stream_index is given, then
-matches stream number stream_index of this type. Otherwise matches all
+
stream_type is one of following: ’v’ for video, ’a’ for audio, ’s’ for subtitle,
+’d’ for data, and ’t’ for attachments. If stream_index is given, then it matches
+stream number stream_index of this type. Otherwise, it matches all
streams of this type.
‘p:program_id[:stream_index]’
-
If stream_index is given, then matches stream number stream_index in
-program with id program_id. Otherwise matches all streams in this program.
+
If stream_index is given, then it matches the stream with number stream_index
+in the program with the id program_id. Otherwise, it matches all streams in the
+program.
+
Show help. An optional parameter may be specified to print help about a specific
+item. If no argument is specified, only basic (non advanced) tool
+options are shown.
+
Possible values of arg are:
+
+
‘long’
+
Print advanced tool options in addition to the basic tool options.
+
+
+
‘full’
+
Print complete list of options, including shared and private options
+for encoders, decoders, demuxers, muxers, filters, etc.
+
+
+
‘decoder=decoder_name’
+
Print detailed information about the decoder named decoder_name. Use the
+‘-decoders’ option to get a list of all decoders.
+
+
+
‘encoder=encoder_name’
+
Print detailed information about the encoder named encoder_name. Use the
+‘-encoders’ option to get a list of all encoders.
+
+
+
‘demuxer=demuxer_name’
+
Print detailed information about the demuxer named demuxer_name. Use the
+‘-formats’ option to get a list of all demuxers and muxers.
+
+
+
‘muxer=muxer_name’
+
Print detailed information about the muxer named muxer_name. Use the
+‘-formats’ option to get a list of all muxers and demuxers.
+
+
+
‘filter=filter_name’
+
Print detailed information about the filter name filter_name. Use the
+‘-filters’ option to get a list of all filters.
+
+
+
‘-version’
Show version.
@@ -546,42 +388,21 @@ program with id program_id. Otherwise matches all streams in this pro
‘-formats’
Show available formats.
-
The fields preceding the format names have the following meanings:
-
-
‘D’
-
Decoding available
-
-
‘E’
-
Encoding available
-
-
-
‘-codecs’
-
Show available codecs.
+
Show all codecs known to libavcodec.
+
+
Note that the term ’codec’ is used throughout this documentation as a shortcut
+for what is more correctly called a media bitstream format.
+
+
+
‘-decoders’
+
Show available decoders.
+
+
+
‘-encoders’
+
Show all available encoders.
-
The fields preceding the codec names have the following meanings:
-
-
‘D’
-
Decoding available
-
-
‘E’
-
Encoding available
-
-
‘V/A/S’
-
Video/audio/subtitle codec
-
-
‘S’
-
Codec supports slices
-
-
‘D’
-
Codec supports direct rendering
-
-
‘T’
-
Codec can handle input truncated at random locations instead of only at frame boundaries
-
-
-
‘-bsfs’
Show available bitstream filters.
@@ -603,18 +424,52 @@ program with id program_id. Otherwise matches all streams in this pro
Show available sample formats.
-
‘-loglevel loglevel | -v loglevel’
+
‘-layouts’
+
Show channel names and standard channel layouts.
+
Set the logging level used by the library.
+Adding "repeat+" indicates that repeated log output should not be compressed
+to the first line and the "Last message repeated n times" line will be
+omitted. "repeat" can also be used alone.
+If "repeat" is used alone, and with no prior loglevel set, the default
+loglevel will be used. If multiple loglevel parameters are given, using
+’repeat’ will not change the loglevel.
loglevel is a number or a string containing one of the following values:
‘quiet’
+
Show nothing at all; be silent.
+
‘panic’
+
Only show fatal errors which could lead the process to crash, such as
+and assert failure. This is not currently used for anything.
+
‘fatal’
+
Only show fatal errors. These are errors after which the process absolutely
+cannot continue after.
+
‘error’
+
Show all errors, including ones which can be recovered from.
+
‘warning’
+
Show all warnings and errors. Any message related to possibly
+incorrect or unexpected events will be shown.
+
‘info’
+
Show informative messages during processing. This is in addition to
+warnings and errors. This is the default value.
+
‘verbose’
+
Same as info, except more verbose.
+
‘debug’
+
Show everything, including debugging information.
+
By default the program logs to stderr, if coloring is supported by the
@@ -633,14 +488,96 @@ directory.
This file can be useful for bug reports.
It also implies -loglevel verbose.
-
Note: setting the environment variable FFREPORT to any value has the
-same effect.
+
Setting the environment variable FFREPORT to any value has the
+same effect. If the value is a ’:’-separated key=value sequence, these
+options will affect the report; options values must be escaped if they
+contain special characters or the options delimiter ’:’ (see the
+“Quoting and escaping” section in the ffmpeg-utils manual). The
+following option is recognized:
+
+
‘file’
+
set the file name to use for the report; %p is expanded to the name
+of the program, %t is expanded to a timestamp, %% is expanded
+to a plain %
+
+
+
+
Errors in parsing the environment variable are not fatal, and will not
+appear in the report.
+
‘-cpuflags flags (global)’
+
Allows setting and clearing cpu flags. This option is intended
+for testing. Do not use it unless you know what you’re doing.
+
Set OpenCL environment options. This option is only available when
+FFmpeg has been compiled with --enable-opencl.
+
+
options must be a list of key=value option pairs
+separated by ’:’. See the “OpenCL Options” section in the
+ffmpeg-utils manual for the list of supported options.
+
These options are provided directly by the libavformat, libavdevice and
libavcodec libraries. To see the list of available AVOptions, use the
@@ -663,22 +600,23 @@ muxer:
ffmpeg -i input.flac -id3v2_version 3 out.mp3
-
All codec AVOptions are obviously per-stream, so the chapter on stream
-specifiers applies to them
+
All codec AVOptions are per-stream, and thus a stream specifier
+should be attached to them.
-
Note ‘-nooption’ syntax cannot be used for boolean AVOptions,
-use ‘-option 0’/‘-option 1’.
+
Note: the ‘-nooption’ syntax cannot be used for boolean
+AVOptions, use ‘-option 0’/‘-option 1’.
-
Note2 old undocumented way of specifying per-stream AVOptions by prepending
-v/a/s to the options name is now obsolete and will be removed soon.
+
Note: the old undocumented way of specifying per-stream AVOptions by
+prepending v/a/s to the options name is now obsolete and will be
+removed soon.
Force input or output file format. The format is normally auto detected for input
-files and guessed from file extension for output files, so this option is not
+files and guessed from the file extension for output files, so this option is not
needed in most cases.
@@ -691,7 +629,8 @@ needed in most cases.
‘-n (global)’
-
Do not overwrite output files but exit if file exists.
+
Do not overwrite output files, and exit immediately if a specified
+output file already exists.
@@ -717,16 +656,31 @@ libx264, and the 138th audio, which will be encoded with libvorbis.
Stop writing the output after its duration reaches duration.
duration may be a number in seconds, or in hh:mm:ss[.xxx] form.
+
-to and -t are mutually exclusive and -t has priority.
+
+
+
‘-to position (output)’
+
Stop writing the output at position.
+position may be a number in seconds, or in hh:mm:ss[.xxx] form.
+
+
-to and -t are mutually exclusive and -t has priority.
+
‘-fs limit_size (output)’
-
Set the file size limit.
+
Set the file size limit, expressed in bytes.
‘-ss position (input/output)’
When used as an input option (before -i), seeks in this input file to
-position. When used as an output option (before an output filename),
-decodes but discards input until the timestamps reach position. This is
-slower, but more accurate.
+position. Note the in most formats it is not possible to seek exactly, so
+ffmpeg will seek to the closest seek point before position.
+When transcoding and ‘-accurate_seek’ is enabled (the default), this
+extra segment between the seek point and position will be decoded and
+discarded. When doing stream copy or when ‘-noaccurate_seek’ is used, it
+will be preserved.
+
+
When used as an output option (before an output filename), decodes but discards
+input until the timestamps reach position.
position may be either in seconds or in hh:mm:ss[.xxx] form.
@@ -742,7 +696,7 @@ streams are delayed by offset seconds.
‘-timestamp time (output)’
Set the recording timestamp in the container.
The syntax for time is:
-
If the value is "now" it takes the current time.
Time is local time unless ’Z’ or ’z’ is appended, in which case it is
@@ -799,18 +753,65 @@ they do not conflict with the standard, as in:
Use fixed quality scale (VBR). The meaning of q is
codec-dependent.
filter_graph is a description of the filter graph to apply to
-the stream. Use -filters to show all the available filters
-(including also sources and sinks).
+
Create the filtergraph specified by filtergraph and use it to
+filter the stream.
+
+
filtergraph is a description of the filtergraph to apply to
+the stream, and must have a single input and a single output of the
+same type of the stream. In the filtergraph, the input is associated
+to the label in, and the output to the label out. See
+the ffmpeg-filters manual for more information about the filtergraph
+syntax.
+
+
See the -filter_complex option if you
+want to create filtergraphs with multiple inputs and/or outputs.
+
This option is similar to ‘-filter’, the only difference is that its
+argument is the name of the file from which a filtergraph description is to be
+read.
+
Print encoding progress/statistics. On by default.
+
Print encoding progress/statistics. It is on by default, to explicitly
+disable it you need to specify -nostats.
+
+
+
‘-progress url (global)’
+
Send program-friendly progress information to url.
+
+
Progress information is written approximately every second and at the end of
+the encoding process. It is made of "key=value" lines. key
+consists of only alphanumeric characters. The last key of a sequence of
+progress information is always "progress".
+
+
+
‘-stdin’
+
Enable interaction on standard input. On by default unless standard input is
+used as an input. To explicitly disable interaction you need to specify
+-nostdin.
+
+
Disabling interaction on standard input is useful, for example, if
+ffmpeg is in the background process group. Roughly the same result can
+be achieved with ffmpeg ... < /dev/null but it requires a
+shell.
+
+
+
‘-debug_ts (global)’
+
Print timestamp information. It is off by default. This option is
+mostly useful for testing and debugging purposes, and the output
+format may change from one version to another, so it should not be
+employed by portable scripts.
+
+
See also the option -fdebug ts.
‘-attach filename (output)’
@@ -834,10 +835,10 @@ with -map or automatic mappings).
will be used.
E.g. to extract the first attachment to a file named ’out.ttf’:
-
ffmpeg -dump_attachment:t:0 out.ttf INPUT
+
ffmpeg -dump_attachment:t:0 out.ttf -i INPUT
To extract all attachments to files determined by the filename tag:
-
ffmpeg -dump_attachment:t "" INPUT
+
ffmpeg -dump_attachment:t "" -i INPUT
Technical note – attachments are implemented as codec extradata, so this
@@ -848,108 +849,35 @@ attachments.
-
Set frame size. The format is ‘wxh’ (default - same as source).
-The following abbreviations are recognized:
-
-
‘sqcif’
-
128x96
-
-
‘qcif’
-
176x144
-
-
‘cif’
-
352x288
-
-
‘4cif’
-
704x576
-
-
‘16cif’
-
1408x1152
-
-
‘qqvga’
-
160x120
-
-
‘qvga’
-
320x240
-
-
‘vga’
-
640x480
-
-
‘svga’
-
800x600
-
-
‘xga’
-
1024x768
-
-
‘uxga’
-
1600x1200
-
-
‘qxga’
-
2048x1536
-
-
‘sxga’
-
1280x1024
-
-
‘qsxga’
-
2560x2048
-
-
‘hsxga’
-
5120x4096
-
-
‘wvga’
-
852x480
-
-
‘wxga’
-
1366x768
-
-
‘wsxga’
-
1600x1024
-
-
‘wuxga’
-
1920x1200
-
-
‘woxga’
-
2560x1600
-
-
‘wqsxga’
-
3200x2048
-
-
‘wquxga’
-
3840x2400
-
-
‘whsxga’
-
6400x4096
-
-
‘whuxga’
-
7680x4800
-
-
‘cga’
-
320x200
-
-
‘ega’
-
640x350
-
-
‘hd480’
-
852x480
-
-
‘hd720’
-
1280x720
-
-
‘hd1080’
-
1920x1080
-
-
-
+
Set frame size.
+
+
As an input option, this is a shortcut for the ‘video_size’ private
+option, recognized by some demuxers for which the frame size is either not
+stored in the file or is configurable – e.g. raw video or video grabbers.
+
+
As an output option, this inserts the scale video filter to the
+end of the corresponding filtergraph. Please use the scale filter
+directly to insert it at the beginning or some other place.
+
Set the video display aspect ratio specified by aspect.
@@ -959,60 +887,20 @@ form num:den, where num and den are
numerator and denominator of the aspect ratio. For example "4:3",
"16:9", "1.3333", and "1.7777" are valid argument values.
-
-
‘-croptop size’
-
‘-cropbottom size’
-
‘-cropleft size’
-
‘-cropright size’
-
All the crop options have been removed. Use -vf
-crop=width:height:x:y instead.
-
-
-
‘-padtop size’
-
‘-padbottom size’
-
‘-padleft size’
-
‘-padright size’
-
‘-padcolor hex_color’
-
All the pad options have been removed. Use -vf
-pad=width:height:x:y:color instead.
+
If used together with ‘-vcodec copy’, it will affect the aspect ratio
+stored at container level, but not the aspect ratio stored in encoded
+frames, if it exists.
‘-vn (output)’
Disable video recording.
-
-
‘-bt tolerance’
-
Set video bitrate tolerance (in bits, default 4000k).
-Has a minimum value of: (target_bitrate/target_framerate).
-In 1-pass mode, bitrate tolerance specifies how far ratecontrol is
-willing to deviate from the target average bitrate value. This is
-not related to min/max bitrate. Lowering tolerance too much has
-an adverse effect on quality.
-
-
‘-maxrate bitrate’
-
Set max video bitrate (in bit/s).
-Requires -bufsize to be set.
-
-
‘-minrate bitrate’
-
Set min video bitrate (in bit/s).
-Most useful in setting up a CBR encode:
-
Set video buffer verifier buffer size (in bits).
-
-
‘-vcodec codec (output)’
-
Set the video codec. This is an alias for -codec:v.
-
-
‘-same_quant’
-
Use same quantizer as source (implies VBR).
-
-
Note that this is NOT SAME QUALITY. Do not use this option unless you know you
-need it.
-
‘-pass n’
+
‘-vcodec codec (output)’
+
Set the video codec. This is an alias for -codec:v.
+
+
+
‘-pass[:stream_specifier] n (output,per-stream)’
Select the pass number (1 or 2). It is used to do two-pass
video encoding. The statistics of the video are recorded in the first
pass into a log file (see also the option -passlogfile),
@@ -1025,7 +913,7 @@ ffmpeg -i foo.mov -c:v libxvid -pass 1 -an -f rawvideo -y /dev/null
Set two-pass log file name prefix to prefix, the default file name
prefix is “ffmpeg2pass”. The complete file name will be
‘PREFIX-N.log’, where N is a number specific to the output
@@ -1036,281 +924,44 @@ stream
Set the ISO 639 language code (3 letters) of the current video stream.
-
‘-vf filter_graph (output)’
-
filter_graph is a description of the filter graph to apply to
-the input video.
-Use the option "-filters" to show all the available filters (including
-also sources and sinks). This is an alias for -filter:v.
+
‘-vf filtergraph (output)’
+
Create the filtergraph specified by filtergraph and use it to
+filter the stream.
-
+
This is an alias for -filter:v, see the -filter option.
+
‘-pix_fmt[:stream_specifier] format (input/output,per-stream)’
Set pixel format. Use -pix_fmts to show all the supported
pixel formats.
-
+If the selected pixel format can not be selected, ffmpeg will print a
+warning and select the best pixel format supported by the encoder.
+If pix_fmt is prefixed by a +, ffmpeg will exit with an error
+if the requested pixel format can not be selected, and automatic conversions
+inside filtergraphs are disabled.
+If pix_fmt is a single +, ffmpeg selects the same pixel format
+as the input (or graph output) and automatic conversions are disabled.
+
+
‘-sws_flags flags (input/output)’
Set SwScaler flags.
-
‘-g gop_size’
-
Set the group of pictures size.
-
-
‘-intra’
-
deprecated, use -g 1
-
‘-vdt n’
Discard threshold.
-
-
‘-qmin q’
-
minimum video quantizer scale (VBR)
-
-
‘-qmax q’
-
maximum video quantizer scale (VBR)
-
-
‘-qdiff q’
-
maximum difference between the quantizer scales (VBR)
-
-
‘-qblur blur’
-
video quantizer scale blur (VBR) (range 0.0 - 1.0)
-
-
‘-qcomp compression’
-
video quantizer scale compression (VBR) (default 0.5).
-Constant of ratecontrol equation. Recommended range for default rc_eq: 0.0-1.0
-
-
‘-lmin lambda’
-
minimum video lagrange factor (VBR)
-
-
‘-lmax lambda’
-
max video lagrange factor (VBR)
-
-
‘-mblmin lambda’
-
minimum macroblock quantizer scale (VBR)
-
-
‘-mblmax lambda’
-
maximum macroblock quantizer scale (VBR)
-
-
These four options (lmin, lmax, mblmin, mblmax) use ’lambda’ units,
-but you may use the QP2LAMBDA constant to easily convert from ’q’ units:
-
ffmpeg -i src.ext -lmax 21*QP2LAMBDA dst.ext
-
-
-
-
‘-rc_init_cplx complexity’
-
initial complexity for single pass encoding
-
-
‘-b_qfactor factor’
-
qp factor between P- and B-frames
-
-
‘-i_qfactor factor’
-
qp factor between P- and I-frames
-
-
‘-b_qoffset offset’
-
qp offset between P- and B-frames
-
-
‘-i_qoffset offset’
-
qp offset between P- and I-frames
-
-
‘-rc_eq equation’
-
Set rate control equation (see section "Expression Evaluation")
-(default = tex^qComp).
-
-
When computing the rate control equation expression, besides the
-standard functions defined in the section "Expression Evaluation", the
-following functions are available:
-
Rate control override for specific intervals, formatted as "int,int,int"
list separated with slashes. Two first values are the beginning and
end frame numbers, last one is quantizer to use if positive, or quality
factor if negative.
-
-
‘-me_method method’
-
Set motion estimation method to method.
-Available methods are (from lowest to best quality):
-
-
‘zero’
-
Try just the (0, 0) vector.
-
-
‘phods’
-
‘log’
-
‘x1’
-
‘hex’
-
‘umh’
-
‘epzs’
-
(default method)
-
-
‘full’
-
exhaustive search (slow and marginally better than epzs)
-
-
-
-
-
‘-dct_algo algo’
-
Set DCT algorithm to algo. Available values are:
-
-
‘0’
-
FF_DCT_AUTO (default)
-
-
‘1’
-
FF_DCT_FASTINT
-
-
‘2’
-
FF_DCT_INT
-
-
‘3’
-
FF_DCT_MMX
-
-
‘4’
-
FF_DCT_MLIB
-
-
‘5’
-
FF_DCT_ALTIVEC
-
-
-
-
-
‘-idct_algo algo’
-
Set IDCT algorithm to algo. Available values are:
-
-
‘0’
-
FF_IDCT_AUTO (default)
-
-
‘1’
-
FF_IDCT_INT
-
-
‘2’
-
FF_IDCT_SIMPLE
-
-
‘3’
-
FF_IDCT_SIMPLEMMX
-
-
‘4’
-
FF_IDCT_LIBMPEG2MMX
-
-
‘5’
-
FF_IDCT_PS2
-
-
‘6’
-
FF_IDCT_MLIB
-
-
‘7’
-
FF_IDCT_ARM
-
-
‘8’
-
FF_IDCT_ALTIVEC
-
-
‘9’
-
FF_IDCT_SH4
-
-
‘10’
-
FF_IDCT_SIMPLEARM
-
-
-
-
-
‘-er n’
-
Set error resilience to n.
-
-
‘1’
-
FF_ER_CAREFUL (default)
-
-
‘2’
-
FF_ER_COMPLIANT
-
-
‘3’
-
FF_ER_AGGRESSIVE
-
-
‘4’
-
FF_ER_VERY_AGGRESSIVE
-
-
-
-
-
‘-ec bit_mask’
-
Set error concealment to bit_mask. bit_mask is a bit mask of
-the following values:
-
-
‘1’
-
FF_EC_GUESS_MVS (default = enabled)
-
-
‘2’
-
FF_EC_DEBLOCK (default = enabled)
-
-
-
-
-
‘-bf frames’
-
Use ’frames’ B-frames (supported for MPEG-1, MPEG-2 and MPEG-4).
-
-
‘-mbd mode’
-
macroblock decision
-
-
‘0’
-
FF_MB_DECISION_SIMPLE: Use mb_cmp (cannot change it yet in ffmpeg).
-
-
‘1’
-
FF_MB_DECISION_BITS: Choose the one which needs the fewest bits.
-
-
‘2’
-
FF_MB_DECISION_RD: rate distortion
-
-
-
-
-
‘-4mv’
-
Use four motion vector by macroblock (MPEG-4 only).
-
-
‘-part’
-
Use data partitioning (MPEG-4 only).
-
-
‘-bug param’
-
Work around encoder bugs that are not auto-detected.
-
-
‘-strict strictness’
-
How strictly to follow the standards.
-
-
‘-aic’
-
Enable Advanced intra coding (h263+).
-
-
‘-umv’
-
Enable Unlimited Motion Vector (h263+)
-
‘-deinterlace’
-
Deinterlace pictures.
-
‘-ilme’
Force interlacing support in encoder (MPEG-2 and MPEG-4 only).
Use this option if your input file is interlaced and you want
@@ -1341,13 +992,61 @@ The alternative is to deinterlace the input stream with
Force key frames at the specified timestamps, more precisely at the first
frames after each specified time.
+
+
If the argument is prefixed with expr:, the string expr
+is interpreted like an expression and is evaluated for each frame. A
+key frame is forced in case the evaluation is non-zero.
+
+
If one of the times is "chapters[delta]", it is expanded into
+the time of the beginning of all chapters in the file, shifted by
+delta, expressed as a time in seconds.
This option can be useful to ensure that a seek point is present at a
chapter mark or any other designated place in the output file.
-The timestamps must be specified in ascending order.
+
+
For example, to insert a key frame at 5 minutes, plus key frames 0.1 second
+before the beginning of every chapter:
+
-force_key_frames 0:05:00,chapters-0.1
+
+
+
The expression in expr can contain the following constants:
+
+
‘n’
+
the number of current processed frame, starting from 0
+
+
‘n_forced’
+
the number of forced frames
+
+
‘prev_forced_n’
+
the number of the previous forced frame, it is NAN when no
+keyframe was forced yet
+
+
‘prev_forced_t’
+
the time of the previous forced frame, it is NAN when no
+keyframe was forced yet
+
+
‘t’
+
the time of the current processed frame
+
+
+
+
For example to force a key frame every 5 seconds, you can specify:
+
-force_key_frames expr:gte(t,n_forced*5)
+
+
+
To force a key frame 5 seconds after the time of the last forced one,
+starting from second 13:
+
Note that forcing too many keyframes is very harmful for the lookahead
+algorithms of certain encoders: using fixed-GOP options or similar
+would be more efficient.
Force audio tag/fourcc. This is an alias for -tag:a.
-
‘-audio_service_type type’
-
Set the type of service that the audio stream contains.
-
-
‘ma’
-
Main Audio Service (default)
-
-
‘ef’
-
Effects
-
-
‘vi’
-
Visually Impaired
-
-
‘hi’
-
Hearing Impaired
-
-
‘di’
-
Dialogue
-
-
‘co’
-
Commentary
-
-
‘em’
-
Emergency
-
-
‘vo’
-
Voice Over
-
-
‘ka’
-
Karaoke
-
-
-
‘-absf bitstream_filter’
Deprecated, see -bsf
+
‘-guess_layout_max channels (input,per-stream)’
+
If some input channel layout is not known, try to guess only if it
+corresponds to at most the specified number of channels. For example, 2
+tells to ffmpeg to recognize 1 channel as mono and 2 channels as
+stereo but not 6 channels as 5.1. The default is to always try to guess. Use
+0 to disable all guessing.
+
Fix subtitles durations. For each subtitle, wait for the next packet in the
+same stream and adjust the duration of the first to avoid overlap. This is
+necessary with some subtitles codecs, especially DVB subtitles, because the
+duration in the original packet is only a rough estimate and the end is
+actually marked by an empty subtitle frame. Failing to use this option when
+necessary can result in exaggerated durations or muxing failures due to
+non-monotonic timestamps.
+
+
Note that this option will delay the output of all data until the next
+subtitle packet is decoded: it may increase memory consumption and latency a
+lot.
+
+
+
‘-canvas_size size’
+
Set the size of the canvas used to render subtitles.
+
Designate one or more input streams as a source for the output file. Each input
stream is identified by the input file index input_file_id and
@@ -1481,6 +1177,10 @@ the source for output stream 1, etc.
A - character before the stream identifier creates a "negative" mapping.
It disables matching streams from already created mappings.
+
An alternative [linklabel] form will map outputs from complex filter
+graphs (see the ‘-filter_complex’ option) to the output file.
+linklabel must correspond to a defined output link label in the graph.
+
For example, to map ALL streams from the first input file to output
ffmpeg -i INPUT -map 0 output
@@ -1514,7 +1214,7 @@ and copy them to the output file ‘out.mov’:
Map an audio channel from a given input to an output. If
-output_file_id.stream_specifier are not set, the audio channel will
+output_file_id.stream_specifier is not set, the audio channel will
be mapped on all the audio streams.
Using "-1" instead of
@@ -1534,18 +1234,18 @@ two audio channels with the following command:
the output stream. The output channel layout is guessed from the number of
channels mapped (mono if one "-map_channel", stereo if two, etc.). Using "-ac"
in combination of "-map_channel" makes the channel gain levels to be updated if
-channel layouts don’t match (for instance two "-map_channel" options and "-ac
-6").
+input and output channel layouts don’t match (for instance two "-map_channel"
+options and "-ac 6").
-
You can also extract each channel of an INPUT to specific outputs; the
-following command extract each channel of the audio stream (file 0, stream 0)
-to the respective OUTPUT_CH0 and OUTPUT_CH1:
+
You can also extract each channel of an input to specific outputs; the following
+command extracts two channels of the INPUT audio stream (file 0, stream 0)
+to the respective OUTPUT_CH0 and OUTPUT_CH1 outputs:
Note that currently each output stream can only contain channels from a single
@@ -1553,9 +1253,16 @@ input stream; you can’t for example use "-map_channel" to pick m
audio channels contained in different streams (from the same or different files)
and merge them into a single output stream. It is therefore not currently
possible, for example, to turn two separate mono streams into a single stereo
-stream. However spliting a stereo stream into two single channel mono streams
+stream. However splitting a stereo stream into two single channel mono streams
is possible.
+
If you need this feature, a possible workaround is to use the amerge
+filter. For example, if you need to merge a media (here ‘input.mkv’) with 2
+mono audio streams into one single stereo channel audio stream (and keep the
+video stream), you can use the following command:
+
Set metadata information of the next output file from infile. Note that
@@ -1606,51 +1313,7 @@ metadata is assumed by default.
output file. If no chapter mapping is specified, then chapters are copied from
the first input file with at least one chapter. Use a negative file index to
disable any chapter copying.
-
-
‘-debug category’
-
Print specific debug info.
-category is a number or a string containing one of the following values:
-
-
‘bitstream’
-
‘buffers’
-
picture buffer allocations
-
-
‘bugs’
-
‘dct_coeff’
-
‘er’
-
error recognition
-
-
‘mb_type’
-
macroblock (MB) type
-
-
‘mmco’
-
memory management control operations (H.264)
-
-
‘mv’
-
motion vector
-
-
‘pict’
-
picture info
-
-
‘pts’
-
‘qp’
-
per-block quantization parameter (QP)
-
-
‘rc’
-
rate control
-
-
‘skip’
-
‘startcode’
-
‘thread_ops’
-
threading operations
-
-
‘vis_mb_type’
-
visualize block types
-
-
‘vis_qp’
-
visualize quantization parameter (QP), lower QP are tinted greener
-
-
+
‘-benchmark (global)’
Show benchmarking information at the end of an encode.
@@ -1658,6 +1321,10 @@ Shows CPU time used and maximum memory consumption.
Maximum memory consumption is not supported on all systems,
it will usually display as 0 if not supported.
+
‘-benchmark_all (global)’
+
Show benchmarking information during the encode.
+Shows CPU time used in various steps (audio/video encode/decode).
+
‘-timelimit duration (global)’
Exit after ffmpeg has been running for duration seconds.
@@ -1667,11 +1334,14 @@ it will usually display as 0 if not supported.
‘-hex (global)’
When dumping packets, also dump the payload.
-
‘-ps size’
-
Set RTP payload size in bytes.
-
‘-re (input)’
Read input at native frame rate. Mainly used to simulate a grab device.
+or live input stream (e.g. when reading from a file). Should not be used
+with actual grab devices or live input streams (where it can cause packet
+loss).
+By default ffmpeg attempts to read the input(s) as fast as possible.
+This option will slow down the reading of the input(s) to the native frame rate
+of the input(s). It is useful for real-time output (e.g. live streaming).
‘-loop_input’
Loop over the input stream. Currently it works only for image
@@ -1683,11 +1353,10 @@ This option is deprecated, use -loop 1.
(0 will loop the output infinitely).
This option is deprecated, use -loop.
-
‘-threads count’
-
Thread count.
-
‘-vsync parameter’
Video sync method.
+For compatibility reasons old values can be specified as numbers.
+Newly added values will have to be specified as strings always.
‘0, passthrough’
@@ -1695,18 +1364,26 @@ This option is deprecated, use -loop.
‘1, cfr’
Frames will be duplicated and dropped to achieve exactly the requested
-constant framerate.
+constant frame rate.
‘2, vfr’
Frames are passed through with their timestamp or dropped so as to
prevent 2 frames from having the same timestamp.
+
‘drop’
+
As passthrough but destroys all timestamps, making the muxer generate
+fresh timestamps based on frame-rate.
+
‘-1, auto’
Chooses between 1 and 2 depending on muxer capabilities. This is the
default method.
+
Note that the timestamps may be further modified by the muxer, after this.
+For example, in the case that the format option ‘avoid_negative_ts’
+is enabled.
+
With -map you can select from which stream the timestamps should be
taken. You can leave either video or audio unchanged and sync the
remaining stream(s) to the unchanged one.
@@ -1717,14 +1394,54 @@ remaining stream(s) to the unchanged one.
the parameter is the maximum samples per second by which the audio is changed.
-async 1 is a special case where only the start of the audio stream is corrected
without any later correction.
-
+
+
Note that the timestamps may be further modified by the muxer, after this.
+For example, in the case that the format option ‘avoid_negative_ts’
+is enabled.
+
+
This option has been deprecated. Use the aresample audio filter instead.
+
+
‘-copyts’
-
Copy timestamps from input to output.
+
Do not process input timestamps, but keep their values without trying
+to sanitize them. In particular, do not remove the initial start time
+offset value.
+
+
Note that, depending on the ‘vsync’ option or on specific muxer
+processing (e.g. in case the format option ‘avoid_negative_ts’
+is enabled) the output timestamps may mismatch with the input
+timestamps even when this option is selected.
+
+
+
‘-copytb mode’
+
Specify how to set the encoder timebase when stream copying. mode is an
+integer numeric value, and can assume one of the following values:
+
+
+
‘1’
+
Use the demuxer timebase.
+
+
The time base is copied to the output encoder from the corresponding input
+demuxer. This is sometimes required to avoid non monotonically increasing
+timestamps when copying video streams with variable frame rate.
+
+
+
‘0’
+
Use the decoder timebase.
+
+
The time base is copied to the output encoder from the corresponding input
+decoder.
+
+
+
‘-1’
+
Try to make the choice automatically, in order to generate a sane output.
-
‘-copytb’
-
Copy input stream time base from input to output when stream copying.
-
-
‘-shortest’
+
+
+
Default value is -1.
+
+
+
‘-shortest (output)’
Finish encoding when the shortest input stream ends.
Set bitstream filters for matching streams. bistream_filters is
+
Set bitstream filters for matching streams. bitstream_filters is
a comma-separated list of bitstream filters. Use the -bsfs option
to get the list of bitstream filters.
-
Define a complex filtergraph, i.e. one with arbitrary number of inputs and/or
+outputs. For simple graphs – those with one input and one output of the same
+type – see the ‘-filter’ options. filtergraph is a description of
+the filtergraph, as described in the “Filtergraph syntax” section of the
+ffmpeg-filters manual.
+
+
Input link labels must refer to input streams using the
+[file_index:stream_specifier] syntax (i.e. the same as ‘-map’
+uses). If stream_specifier matches multiple streams, the first one will be
+used. An unlabeled input will be connected to the first unused input stream of
+the matching type.
+
+
Output link labels are referred to with ‘-map’. Unlabeled outputs are
+added to the first output file.
+
+
Note that with this option it is possible to use only lavfi sources without
+normal input files.
+
Here [0:v] refers to the first video stream in the first input file,
+which is linked to the first (main) input of the overlay filter. Similarly the
+first video stream in the second input is linked to the second (overlay) input
+of overlay.
+
+
Assuming there is only one video stream in each input file, we can omit input
+labels, so the above is equivalent to
+
Furthermore we can omit the output label and the single output from the filter
+graph will be added to the output file automatically, so we can simply write
+
Define a complex filtergraph, i.e. one with arbitrary number of inputs and/or
+outputs. Equivalent to ‘-filter_complex’.
+
+
+
‘-filter_complex_script filename (global)’
+
This option is similar to ‘-filter_complex’, the only difference is that
+its argument is the name of the file from which a complex filtergraph
+description is to be read.
+
+
+
‘-accurate_seek (input)’
+
This option enables or disables accurate seeking in input files with the
+‘-ss’ option. It is enabled by default, so seeking is accurate when
+transcoding. Use ‘-noaccurate_seek’ to disable it, which may be useful
+e.g. when copying some streams and transcoding the others.
+
+
+
‘-override_ffserver (global)’
+
Overrides the input specifications from ffserver. Using this option you can
+map any input stream to ffserver and control many aspects of the encoding from
+ffmpeg. Without this option ffmpeg will transmit to ffserver what is requested by
+ffserver.
+The option is intended for cases where features are needed that cannot be
+specified to ffserver but can be to ffmpeg.
+
As a special exception, you can use a bitmap subtitle stream as input: it
+will be converted into a video with the same size as the largest video in
+the file, or 720x576 if no video is present. Note that this is an
+experimental and temporary solution. It will be removed once libavfilter has
+proper support for subtitles.
+
+
For example, to hardcode subtitles on top of a DVB-T recording stored in
+MPEG-TS format, delaying the subtitles by 1 second:
+
A preset file contains a sequence of option=value pairs,
one for each line, specifying a sequence of options which would be
awkward to specify on the command line. Lines starting with the hash
@@ -1794,22 +1599,22 @@ following rules:
directories ‘$FFMPEG_DATADIR’ (if set), and ‘$HOME/.ffmpeg’, and in
the datadir defined at configuration time (usually ‘PREFIX/share/ffmpeg’)
or in a ‘ffpresets’ folder along the executable on win32,
-in that order. For example, if the argument is libx264-max, it will
-search for the file ‘libx264-max.ffpreset’.
+in that order. For example, if the argument is libvpx-1080p, it will
+search for the file ‘libvpx-1080p.ffpreset’.
If no such file is found, then ffmpeg will search for a file named
codec_name-arg.ffpreset in the above-mentioned
directories, where codec_name is the name of the codec to which
the preset file options will be applied. For example, if you select
-the video codec with -vcodec libx264 and use -vpre max,
-then it will search for the file ‘libx264-max.ffpreset’.
+the video codec with -vcodec libvpx and use -vpre 1080p,
+then it will search for the file ‘libvpx-1080p.ffpreset’.
-For streaming at very low bitrate application, use a low frame rate
+For streaming at very low bitrates, use a low frame rate
and a small GOP size. This is especially true for RealVideo where
the Linux player does not seem to be very fast, so it can miss
frames. An example is:
@@ -1828,7 +1633,7 @@ frame rate or decrease the frame size.
If your computer is not fast enough, you can speed up the
compression at the expense of the compression ratio. You can use
-’-me zero’ to speed up motion estimation, and ’-intra’ to disable
+’-me zero’ to speed up motion estimation, and ’-g 0’ to disable
motion estimation completely (you have only I-frames, which means it
is about as good as JPEG compression).
@@ -1844,10 +1649,10 @@ quality).
A preset file contains a sequence of option=value pairs, one for
each line, specifying a sequence of options which can be specified also on
@@ -1863,7 +1668,7 @@ in that order. For example, if the argument is libx264-max, it wil
search for the file ‘libx264-max.avpreset’.
If you specify the input format and device then ffmpeg can grab video
and audio directly.
@@ -1882,24 +1687,24 @@ have to set the audio recording levels correctly with a
standard mixer.
Any supported file format and protocol can serve as input to ffmpeg:
@@ -2006,6398 +1811,67 @@ composed of three digits padded with zeroes to express the sequence
number. It is the same syntax supported by the C printf function, but
only formats accepting a normal integer are suitable.
+
When importing an image sequence, -i also supports expanding
+shell-like wildcard patterns (globbing) internally, by selecting the
+image2-specific -pattern_type glob option.
+
+
For example, for creating a video from filenames matching the glob pattern
+foo-*.jpeg:
+
When evaluating an arithmetic expression, FFmpeg uses an internal
-formula evaluator, implemented through the ‘libavutil/eval.h’
-interface.
-
-
An expression may contain unary, binary operators, constants, and
-functions.
-
-
Two expressions expr1 and expr2 can be combined to form
-another expression "expr1;expr2".
-expr1 and expr2 are evaluated in turn, and the new
-expression evaluates to the value of expr2.
-
-
The following binary operators are available: +, -,
-*, /, ^.
-
-
The following unary operators are available: +, -.
-
-
The following functions are available:
-
-
‘sinh(x)’
-
‘cosh(x)’
-
‘tanh(x)’
-
‘sin(x)’
-
‘cos(x)’
-
‘tan(x)’
-
‘atan(x)’
-
‘asin(x)’
-
‘acos(x)’
-
‘exp(x)’
-
‘log(x)’
-
‘abs(x)’
-
‘squish(x)’
-
‘gauss(x)’
-
‘isnan(x)’
-
Return 1.0 if x is NAN, 0.0 otherwise.
-
-
-
‘mod(x, y)’
-
‘max(x, y)’
-
‘min(x, y)’
-
‘eq(x, y)’
-
‘gte(x, y)’
-
‘gt(x, y)’
-
‘lte(x, y)’
-
‘lt(x, y)’
-
‘st(var, expr)’
-
Allow to store the value of the expression expr in an internal
-variable. var specifies the number of the variable where to
-store the value, and it is a value ranging from 0 to 9. The function
-returns the value stored in the internal variable.
-Note, Variables are currently not shared between expressions.
-
-
-
‘ld(var)’
-
Allow to load the value of the internal variable with number
-var, which was previously stored with st(var, expr).
-The function returns the loaded value.
-
-
-
‘while(cond, expr)’
-
Evaluate expression expr while the expression cond is
-non-zero, and returns the value of the last expr evaluation, or
-NAN if cond was always false.
-
-
-
‘ceil(expr)’
-
Round the value of expression expr upwards to the nearest
-integer. For example, "ceil(1.5)" is "2.0".
-
-
-
‘floor(expr)’
-
Round the value of expression expr downwards to the nearest
-integer. For example, "floor(-1.5)" is "-2.0".
-
-
-
‘trunc(expr)’
-
Round the value of expression expr towards zero to the nearest
-integer. For example, "trunc(-1.5)" is "-1.0".
-
-
-
‘sqrt(expr)’
-
Compute the square root of expr. This is equivalent to
-"(expr)^.5".
-
-
-
‘not(expr)’
-
Return 1.0 if expr is zero, 0.0 otherwise.
-
-
-
‘pow(x, y)’
-
Compute the power of x elevated y, it is equivalent to
-"(x)^(y)".
-
-
-
‘random(x)’
-
Return a pseudo random value between 0.0 and 1.0. x is the index of the
-internal variable which will be used to save the seed/state.
-
-
-
‘hypot(x, y)’
-
This function is similar to the C function with the same name; it returns
-"sqrt(x*x + y*y)", the length of the hypotenuse of a
-right triangle with sides of length x and y, or the distance of the
-point (x, y) from the origin.
-
-
-
‘gcd(x, y)’
-
Return the greatest common divisor of x and y. If both x and
-y are 0 or either or both are less than zero then behavior is undefined.
-
-
-
‘if(x, y)’
-
Evaluate x, and if the result is non-zero return the result of
-the evaluation of y, return 0 otherwise.
-
-
-
‘ifnot(x, y)’
-
Evaluate x, and if the result is zero return the result of the
-evaluation of y, return 0 otherwise.
-
-
-
-
The following constants are available:
-
-
‘PI’
-
area of the unit disc, approximately 3.14
-
-
‘E’
-
exp(1) (Euler’s number), approximately 2.718
-
-
‘PHI’
-
golden ratio (1+sqrt(5))/2, approximately 1.618
-
-
-
-
Assuming that an expression is considered "true" if it has a non-zero
-value, note that:
-
-
* works like AND
-
-
+ works like OR
-
-
and the construct:
-
if A then B else C
-
-
is equivalent to
-
if(A,B) + ifnot(A,C)
-
-
-
In your C code, you can extend the list of unary and binary functions,
-and define recognized constants, so that they are available for your
-expressions.
-
-
The evaluator also recognizes the International System number
-postfixes. If ’i’ is appended after the postfix, powers of 2 are used
-instead of powers of 10. The ’B’ postfix multiplies the value for 8,
-and can be appended after another postfix or used alone. This allows
-using for example ’KB’, ’MiB’, ’G’ and ’B’ as postfix.
-
-
Follows the list of available International System postfixes, with
-indication of the corresponding powers of 10 and of 2.
-
Decoders are configured elements in FFmpeg which allow the decoding of
-multimedia streams.
-
-
When you configure your FFmpeg build, all the supported native decoders
-are enabled by default. Decoders requiring an external library must be enabled
-manually via the corresponding --enable-lib option. You can list all
-available decoders using the configure option --list-decoders.
-
-
You can disable all the decoders with the configure option
---disable-decoders and selectively enable / disable single decoders
-with the options --enable-decoder=DECODER /
---disable-decoder=DECODER.
-
-
The option -codecs of the ff* tools will display the list of
-enabled decoders.
-
This decoder generates wave patterns according to predefined sequences. Its
-use is purely internal and the format of the data it accepts is not publicly
-documented.
-
Encoders are configured elements in FFmpeg which allow the encoding of
-multimedia streams.
-
-
When you configure your FFmpeg build, all the supported native encoders
-are enabled by default. Encoders requiring an external library must be enabled
-manually via the corresponding --enable-lib option. You can list all
-available encoders using the configure option --list-encoders.
-
-
You can disable all the encoders with the configure option
---disable-encoders and selectively enable / disable single encoders
-with the options --enable-encoder=ENCODER /
---disable-encoder=ENCODER.
-
-
The option -codecs of the ff* tools will display the list of
-enabled encoders.
-
These encoders implement part of ATSC A/52:2010 and ETSI TS 102 366, as well as
-the undocumented RealAudio 3 (a.k.a. dnet).
-
-
The ac3 encoder uses floating-point math, while the ac3_fixed
-encoder only uses fixed-point integer math. This does not mean that one is
-always faster, just that one or the other may be better suited to a
-particular system. The floating-point encoder will generally produce better
-quality audio for a given bitrate. The ac3_fixed encoder is not the
-default codec for any of the output formats, so it must be specified explicitly
-using the option -acodec ac3_fixed in order to use it.
-
The AC-3 metadata options are used to set parameters that describe the audio,
-but in most cases do not affect the audio encoding itself. Some of the options
-do directly affect or influence the decoding and playback of the resulting
-bitstream, while others are just for informational purposes. A few of the
-options will add bits to the output stream that could otherwise be used for
-audio data, and will thus affect the quality of the output. Those will be
-indicated accordingly with a note in the option list below.
-
-
These parameters are described in detail in several publicly-available
-documents.
-
Center Mix Level. The amount of gain the decoder should apply to the center
-channel when downmixing to stereo. This field will only be written to the
-bitstream if a center channel is present. The value is specified as a scale
-factor. There are 3 valid values:
-
-
‘0.707’
-
Apply -3dB gain
-
-
‘0.595’
-
Apply -4.5dB gain (default)
-
-
‘0.500’
-
Apply -6dB gain
-
-
-
-
-
‘-surround_mixlev level’
-
Surround Mix Level. The amount of gain the decoder should apply to the surround
-channel(s) when downmixing to stereo. This field will only be written to the
-bitstream if one or more surround channels are present. The value is specified
-as a scale factor. There are 3 valid values:
-
Audio Production Information is optional information describing the mixing
-environment. Either none or both of the fields are written to the bitstream.
-
-
-
‘-mixing_level number’
-
Mixing Level. Specifies peak sound pressure level (SPL) in the production
-environment when the mix was mastered. Valid values are 80 to 111, or -1 for
-unknown or not indicated. The default value is -1, but that value cannot be
-used if the Audio Production Information is written to the bitstream. Therefore,
-if the room_type option is not the default value, the mixing_level
-option must not be -1.
-
-
-
‘-room_type type’
-
Room Type. Describes the equalization used during the final mixing session at
-the studio or on the dubbing stage. A large room is a dubbing stage with the
-industry standard X-curve equalization; a small room has flat equalization.
-This field will not be written to the bitstream if both the mixing_level
-option and the room_type option have the default values.
-
Copyright Indicator. Specifies whether a copyright exists for this audio.
-
-
‘0’
-
‘off’
-
No Copyright Exists (default)
-
-
‘1’
-
‘on’
-
Copyright Exists
-
-
-
-
-
‘-dialnorm value’
-
Dialogue Normalization. Indicates how far the average dialogue level of the
-program is below digital 100% full scale (0 dBFS). This parameter determines a
-level shift during audio reproduction that sets the average volume of the
-dialogue to a preset level. The goal is to match volume level between program
-sources. A value of -31dB will result in no volume level change, relative to
-the source volume, during audio reproduction. Valid values are whole numbers in
-the range -31 to -1, with -31 being the default.
-
-
-
‘-dsur_mode mode’
-
Dolby Surround Mode. Specifies whether the stereo signal uses Dolby Surround
-(Pro Logic). This field will only be written to the bitstream if the audio
-stream is stereo. Using this option does NOT mean the encoder will actually
-apply Dolby Surround processing.
-
-
‘0’
-
‘notindicated’
-
Not Indicated (default)
-
-
‘1’
-
‘off’
-
Not Dolby Surround Encoded
-
-
‘2’
-
‘on’
-
Dolby Surround Encoded
-
-
-
-
-
‘-original boolean’
-
Original Bit Stream Indicator. Specifies whether this audio is from the
-original source and not a copy.
-
The extended bitstream options are part of the Alternate Bit Stream Syntax as
-specified in Annex D of the A/52:2010 standard. It is grouped into 2 parts.
-If any one parameter in a group is specified, all values in that group will be
-written to the bitstream. Default values are used for those that are written
-but have not been specified. If the mixing levels are written, the decoder
-will use these values instead of the ones specified in the center_mixlev
-and surround_mixlev options if it supports the Alternate Bit Stream
-Syntax.
-
Preferred Stereo Downmix Mode. Allows the user to select either Lt/Rt
-(Dolby Surround) or Lo/Ro (normal stereo) as the preferred stereo downmix mode.
-
-
‘0’
-
‘notindicated’
-
Not Indicated (default)
-
-
‘1’
-
‘ltrt’
-
Lt/Rt Downmix Preferred
-
-
‘2’
-
‘loro’
-
Lo/Ro Downmix Preferred
-
-
-
-
-
‘-ltrt_cmixlev level’
-
Lt/Rt Center Mix Level. The amount of gain the decoder should apply to the
-center channel when downmixing to stereo in Lt/Rt mode.
-
-
‘1.414’
-
Apply +3dB gain
-
-
‘1.189’
-
Apply +1.5dB gain
-
-
‘1.000’
-
Apply 0dB gain
-
-
‘0.841’
-
Apply -1.5dB gain
-
-
‘0.707’
-
Apply -3.0dB gain
-
-
‘0.595’
-
Apply -4.5dB gain (default)
-
-
‘0.500’
-
Apply -6.0dB gain
-
-
‘0.000’
-
Silence Center Channel
-
-
-
-
-
‘-ltrt_surmixlev level’
-
Lt/Rt Surround Mix Level. The amount of gain the decoder should apply to the
-surround channel(s) when downmixing to stereo in Lt/Rt mode.
-
-
‘0.841’
-
Apply -1.5dB gain
-
-
‘0.707’
-
Apply -3.0dB gain
-
-
‘0.595’
-
Apply -4.5dB gain
-
-
‘0.500’
-
Apply -6.0dB gain (default)
-
-
‘0.000’
-
Silence Surround Channel(s)
-
-
-
-
-
‘-loro_cmixlev level’
-
Lo/Ro Center Mix Level. The amount of gain the decoder should apply to the
-center channel when downmixing to stereo in Lo/Ro mode.
-
-
‘1.414’
-
Apply +3dB gain
-
-
‘1.189’
-
Apply +1.5dB gain
-
-
‘1.000’
-
Apply 0dB gain
-
-
‘0.841’
-
Apply -1.5dB gain
-
-
‘0.707’
-
Apply -3.0dB gain
-
-
‘0.595’
-
Apply -4.5dB gain (default)
-
-
‘0.500’
-
Apply -6.0dB gain
-
-
‘0.000’
-
Silence Center Channel
-
-
-
-
-
‘-loro_surmixlev level’
-
Lo/Ro Surround Mix Level. The amount of gain the decoder should apply to the
-surround channel(s) when downmixing to stereo in Lo/Ro mode.
-
Dolby Surround EX Mode. Indicates whether the stream uses Dolby Surround EX
-(7.1 matrixed to 5.1). Using this option does NOT mean the encoder will actually
-apply Dolby Surround EX processing.
-
-
‘0’
-
‘notindicated’
-
Not Indicated (default)
-
-
‘1’
-
‘on’
-
Dolby Surround EX Off
-
-
‘2’
-
‘off’
-
Dolby Surround EX On
-
-
-
-
-
‘-dheadphone_mode mode’
-
Dolby Headphone Mode. Indicates whether the stream uses Dolby Headphone
-encoding (multi-channel matrixed to 2.0 for use with headphones). Using this
-option does NOT mean the encoder will actually apply Dolby Headphone
-processing.
-
-
‘0’
-
‘notindicated’
-
Not Indicated (default)
-
-
‘1’
-
‘on’
-
Dolby Headphone Off
-
-
‘2’
-
‘off’
-
Dolby Headphone On
-
-
-
-
-
‘-ad_conv_type type’
-
A/D Converter Type. Indicates whether the audio has passed through HDCD A/D
-conversion.
-
Stereo Rematrixing. Enables/Disables use of rematrixing for stereo input. This
-is an optional AC-3 feature that increases quality by selectively encoding
-the left/right channels as mid/side. This option is enabled by default, and it
-is highly recommended that it be left as enabled except for testing purposes.
-
These options are only valid for the floating-point encoder and do not exist
-for the fixed-point encoder due to the corresponding features not being
-implemented in fixed-point.
-
-
-
‘-channel_coupling boolean’
-
Enables/Disables use of channel coupling, which is an optional AC-3 feature
-that increases quality by combining high frequency information from multiple
-channels into a single channel. The per-channel high frequency information is
-sent with less accuracy in both the frequency and time domains. This allows
-more bits to be used for lower frequencies while preserving enough information
-to reconstruct the high frequencies. This option is enabled by default for the
-floating-point encoder and should generally be left as enabled except for
-testing purposes or to increase encoding speed.
-
-
‘-1’
-
‘auto’
-
Selected by Encoder (default)
-
-
‘0’
-
‘off’
-
Disable Channel Coupling
-
-
‘1’
-
‘on’
-
Enable Channel Coupling
-
-
-
-
-
‘-cpl_start_band number’
-
Coupling Start Band. Sets the channel coupling start band, from 1 to 15. If a
-value higher than the bandwidth is used, it will be reduced to 1 less than the
-coupling end band. If auto is used, the start band will be determined by
-the encoder based on the bit rate, sample rate, and channel layout. This option
-has no effect if channel coupling is disabled.
-
Demuxers are configured elements in FFmpeg which allow to read the
-multimedia streams from a particular type of file.
-
-
When you configure your FFmpeg build, all the supported demuxers
-are enabled by default. You can list all available ones using the
-configure option "–list-demuxers".
-
-
You can disable all the demuxers using the configure option
-"–disable-demuxers", and selectively enable a single demuxer with
-the option "–enable-demuxer=DEMUXER", or disable it
-with the option "–disable-demuxer=DEMUXER".
-
-
The option "-formats" of the ff* tools will display the list of
-enabled demuxers.
-
-
The description of some of the currently available demuxers follows.
-
This demuxer reads from a list of image files specified by a pattern.
-
-
The pattern may contain the string "%d" or "%0Nd", which
-specifies the position of the characters representing a sequential
-number in each filename matched by the pattern. If the form
-"%d0Nd" is used, the string representing the number in each
-filename is 0-padded and N is the total number of 0-padded
-digits representing the number. The literal character ’%’ can be
-specified in the pattern with the string "%%".
-
-
If the pattern contains "%d" or "%0Nd", the first filename of
-the file list specified by the pattern must contain a number
-inclusively contained between 0 and 4, all the following numbers must
-be sequential. This limitation may be hopefully fixed.
-
-
The pattern may contain a suffix which is used to automatically
-determine the format of the images contained in the files.
-
-
For example the pattern "img-%03d.bmp" will match a sequence of
-filenames of the form ‘img-001.bmp’, ‘img-002.bmp’, ...,
-‘img-010.bmp’, etc.; the pattern "i%%m%%g-%d.jpg" will match a
-sequence of filenames of the form ‘i%m%g-1.jpg’,
-‘i%m%g-2.jpg’, ..., ‘i%m%g-10.jpg’, etc.
-
-
The size, the pixel format, and the format of each image must be the
-same for all the files in the sequence.
-
-
The following example shows how to use ffmpeg for creating a
-video from the images in the file sequence ‘img-001.jpeg’,
-‘img-002.jpeg’, ..., assuming an input frame rate of 10 frames per
-second:
-
ffmpeg -i 'img-%03d.jpeg' -r 10 out.mkv
-
-
-
Note that the pattern must not necessarily contain "%d" or
-"%0Nd", for example to convert a single image file
-‘img.jpeg’ you can employ the command:
-
This demuxer presents all AVStreams from all variant streams.
-The id field is set to the bitrate variant index number. By setting
-the discard flags on AVStreams (by pressing ’a’ or ’v’ in ffplay),
-the caller can decide which variant streams to actually receive.
-The total bitrate of the variant that the stream belongs to is
-available in a metadata key named "variant_bitrate".
-
This demuxer reads the script language used by SBaGen
-http://uazu.net/sbagen/ to generate binaural beats sessions. A SBG
-script looks like that:
-
-SE
-a: 300-2.5/3 440+4.5/0
-b: 300-2.5/0 440+4.5/3
-off: -
-NOW == a
-+0:07:00 == b
-+0:14:00 == a
-+0:21:00 == b
-+0:30:00 off
-
-
-
A SBG script can mix absolute and relative timestamps. If the script uses
-either only absolute timestamps (including the script start time) or only
-relative ones, then its layout is fixed, and the conversion is
-straightforward. On the other hand, if the script mixes both kind of
-timestamps, then the NOW reference for relative timestamps will be
-taken from the current time of day at the time the script is read, and the
-script layout will be frozen according to that reference. That means that if
-the script is directly played, the actual times will match the absolute
-timestamps up to the sound controller’s clock accuracy, but if the user
-somehow pauses the playback or seeks, all times will be shifted accordingly.
-
Muxers are configured elements in FFmpeg which allow writing
-multimedia streams to a particular type of file.
-
-
When you configure your FFmpeg build, all the supported muxers
-are enabled by default. You can list all available muxers using the
-configure option --list-muxers.
-
-
You can disable all the muxers with the configure option
---disable-muxers and selectively enable / disable single muxers
-with the options --enable-muxer=MUXER /
---disable-muxer=MUXER.
-
-
The option -formats of the ff* tools will display the list of
-enabled muxers.
-
-
A description of some of the currently available muxers follows.
-
This muxer computes and prints the Adler-32 CRC of all the input audio
-and video frames. By default audio frames are converted to signed
-16-bit raw audio and video frames to raw video before computing the
-CRC.
-
-
The output of the muxer consists of a single line of the form:
-CRC=0xCRC, where CRC is a hexadecimal number 0-padded to
-8 digits containing the CRC for all the decoded input frames.
-
-
For example to compute the CRC of the input, and store it in the file
-‘out.crc’:
-
ffmpeg -i INPUT -f crc out.crc
-
-
-
You can print the CRC to stdout with the command:
-
ffmpeg -i INPUT -f crc -
-
-
-
You can select the output format of each frame with ffmpeg by
-specifying the audio and video codec and format. For example to
-compute the CRC of the input audio converted to PCM unsigned 8-bit
-and the input video converted to MPEG-2 video, use the command:
-
This muxer computes and prints the Adler-32 CRC for each decoded audio
-and video frame. By default audio frames are converted to signed
-16-bit raw audio and video frames to raw video before computing the
-CRC.
-
-
The output of the muxer consists of a line for each audio and video
-frame of the form: stream_index, frame_dts,
-frame_size, 0xCRC, where CRC is a hexadecimal
-number 0-padded to 8 digits containing the CRC of the decoded frame.
-
-
For example to compute the CRC of each decoded frame in the input, and
-store it in the file ‘out.crc’:
-
ffmpeg -i INPUT -f framecrc out.crc
-
-
-
You can print the CRC of each decoded frame to stdout with the command:
-
ffmpeg -i INPUT -f framecrc -
-
-
-
You can select the output format of each frame with ffmpeg by
-specifying the audio and video codec and format. For example, to
-compute the CRC of each decoded input audio frame converted to PCM
-unsigned 8-bit and of each decoded input video frame converted to
-MPEG-2 video, use the command:
-
The image file muxer writes video frames to image files.
-
-
The output filenames are specified by a pattern, which can be used to
-produce sequentially numbered series of files.
-The pattern may contain the string "%d" or "%0Nd", this string
-specifies the position of the characters representing a numbering in
-the filenames. If the form "%0Nd" is used, the string
-representing the number in each filename is 0-padded to N
-digits. The literal character ’%’ can be specified in the pattern with
-the string "%%".
-
-
If the pattern contains "%d" or "%0Nd", the first filename of
-the file list specified will contain the number 1, all the following
-numbers will be sequential.
-
-
The pattern may contain a suffix which is used to automatically
-determine the format of the image files to write.
-
-
For example the pattern "img-%03d.bmp" will specify a sequence of
-filenames of the form ‘img-001.bmp’, ‘img-002.bmp’, ...,
-‘img-010.bmp’, etc.
-The pattern "img%%-%d.jpg" will specify a sequence of filenames of the
-form ‘img%-1.jpg’, ‘img%-2.jpg’, ..., ‘img%-10.jpg’,
-etc.
-
-
The following example shows how to use ffmpeg for creating a
-sequence of files ‘img-001.jpeg’, ‘img-002.jpeg’, ...,
-taking one image every second from the input video:
-
Note that with ffmpeg, if the format is not specified with the
--f option and the output filename specifies an image file
-format, the image2 muxer is automatically selected, so the previous
-command can be written as:
-
ffmpeg -i in.avi -vsync 1 -r 1 'img-%03d.jpeg'
-
-
-
Note also that the pattern must not necessarily contain "%d" or
-"%0Nd", for example to create a single image file
-‘img.jpeg’ from the input video you can employ the command:
-
ffmpeg -i in.avi -f image2 -frames:v 1 img.jpeg
-
-
-
The image muxer supports the .Y.U.V image file format. This format is
-special in that that each image frame consists of three files, for
-each of the YUV420P components. To read or write this image file format,
-specify the name of the ’.Y’ file. The muxer will automatically open the
-’.U’ and ’.V’ files as required.
-
Reserves space for the moov atom at the beginning of the file instead of placing the
-moov atom at the end. If the space reserved is insufficient, muxing will fail.
-
This muxer implements ISO 13818-1 and part of ETSI EN 300 468.
-
-
The muxer options are:
-
-
-
‘-mpegts_original_network_id number’
-
Set the original_network_id (default 0x0001). This is unique identifier
-of a network in DVB. Its main use is in the unique identification of a
-service through the path Original_Network_ID, Transport_Stream_ID.
-
-
‘-mpegts_transport_stream_id number’
-
Set the transport_stream_id (default 0x0001). This identifies a
-transponder in DVB.
-
-
‘-mpegts_service_id number’
-
Set the service_id (default 0x0001) also known as program in DVB.
-
-
‘-mpegts_pmt_start_pid number’
-
Set the first PID for PMT (default 0x1000, max 0x1f00).
-
-
‘-mpegts_start_pid number’
-
Set the first PID for data packets (default 0x0100, max 0x0f00).
-
-
-
-
The recognized metadata settings in mpegts muxer are service_provider
-and service_name. If they are not set the default for
-service_provider is "FFmpeg" and the default for
-service_name is "Service01".
-
The segmenter muxer outputs streams to a number of separate files of nearly
-fixed duration. Output filename pattern can be set in a fashion similar to
-image2.
-
-
Every segment starts with a video keyframe, if a video stream is present.
-The segment muxer works best with a single constant frame rate video.
-
-
Optionally it can generate a flat list of the created segments, one segment
-per line.
-
-
-
‘segment_format format’
-
Override the inner container format, by default it is guessed by the filename
-extension.
-
-
‘segment_time t’
-
Set segment duration to t seconds.
-
-
‘segment_list name’
-
Generate also a listfile named name.
-
-
‘segment_list_size size’
-
Overwrite the listfile once it reaches size entries.
-
Input devices are configured elements in FFmpeg which allow to access
-the data coming from a multimedia device attached to your system.
-
-
When you configure your FFmpeg build, all the supported input devices
-are enabled by default. You can list all available ones using the
-configure option "–list-indevs".
-
-
You can disable all the input devices using the configure option
-"–disable-indevs", and selectively enable an input device using the
-option "–enable-indev=INDEV", or you can disable a particular
-input device using the option "–disable-indev=INDEV".
-
-
The option "-formats" of the ff* tools will display the list of
-supported input devices (amongst the demuxers).
-
-
A description of the currently available input devices follows.
-
-Print the list of supported options in selected device and exit:
-
$ ffmpeg -list_options true -f dshow -i video="Camera"
+The four options lmin, lmax, mblmin and mblmax use ’lambda’ units,
+but you may use the QP2LAMBDA constant to easily convert from ’q’ units:
+
The Linux framebuffer is a graphic hardware-independent abstraction
-layer to show graphics on a computer monitor, typically on the
-console. It is accessed through a file device node, usually
-‘/dev/fb0’.
-
-
For more detailed information read the file
-Documentation/fb/framebuffer.txt included in the Linux source tree.
-
-
To record from the framebuffer device ‘/dev/fb0’ with
-ffmpeg:
-
ffmpeg -f fbdev -r 10 -i /dev/fb0 out.avi
-
-
-
You can take a single screenshot image with the command:
-
To enable this input device during configuration you need libjack
-installed on your system.
-
-
A JACK input device creates one or more JACK writable clients, one for
-each audio channel, with name client_name:input_N, where
-client_name is the name provided by the application, and N
-is a number which identifies the channel.
-Each writable client will send the acquired data to the FFmpeg input
-device.
-
-
Once you have created one or more JACK readable clients, you need to
-connect them to one or more JACK writable clients.
-
-
To connect or disconnect JACK clients you can use the jack_connect
-and jack_disconnect programs, or do it through a graphical interface,
-for example with qjackctl.
-
-
To list the JACK clients and their properties you can invoke the command
-jack_lsp.
-
-
Follows an example which shows how to capture a JACK readable client
-with ffmpeg.
-
# Create a JACK writable client with name "ffmpeg".
-$ ffmpeg -f jack -i ffmpeg -y out.wav
-
-# Start the sample jack_metro readable client.
-$ jack_metro -b 120 -d 0.2 -f 4000
-
-# List the current JACK clients.
-$ jack_lsp -c
-system:capture_1
-system:capture_2
-system:playback_1
-system:playback_2
-ffmpeg:input_1
-metro:120_bpm
-
-# Connect metro to the ffmpeg writable client.
-$ jack_connect metro:120_bpm ffmpeg:input_1
-
This input device reads data from the open output pads of a libavfilter
-filtergraph.
-
-
For each filtergraph open output, the input device will create a
-corresponding stream which is mapped to the generated output. Currently
-only video data is supported. The filtergraph is specified through the
-option ‘graph’.
-
Specify the filtergraph to use as input. Each video open output must be
-labelled by a unique string of the form "outN", where N is a
-number starting from 0 corresponding to the mapped input stream
-generated by the device.
-The first unlabelled output is automatically assigned to the "out0"
-label, but all the others need to be specified explicitly.
-
-
If not specified defaults to the filename specified for the input
-device.
-
The OpenAL input device provides audio capture on all systems with a
-working OpenAL 1.1 implementation.
-
-
To enable this input device during configuration, you need OpenAL
-headers and libraries installed on your system, and need to configure
-FFmpeg with --enable-openal.
-
-
OpenAL headers and libraries should be provided as part of your OpenAL
-implementation, or as an additional download (an SDK). Depending on your
-installation you may need to specify additional flags via the
---extra-cflags and --extra-ldflags for allowing the build
-system to locate the OpenAL headers and libraries.
-
-
An incomplete list of OpenAL implementations follows:
-
-
-
Creative
-
The official Windows implementation, providing hardware acceleration
-with supported devices and software fallback.
-See http://openal.org/.
-
-
OpenAL Soft
-
Portable, open source (LGPL) software implementation. Includes
-backends for the most common sound APIs on the Windows, Linux,
-Solaris, and BSD operating systems.
-See http://kcat.strangesoft.net/openal.html.
-
This device allows to capture from an audio input device handled
-through OpenAL.
-
-
You need to specify the name of the device to capture in the provided
-filename. If the empty string is provided, the device will
-automatically select the default device. You can get the list of the
-supported devices by using the option list_devices.
-
Video4Linux and Video4Linux2 input video devices.
-
-
The name of the device to grab is a file device node, usually Linux
-systems tend to automatically create such nodes when the device
-(e.g. an USB webcam) is plugged into the system, and has a name of the
-kind ‘/dev/videoN’, where N is a number associated to
-the device.
-
-
Video4Linux and Video4Linux2 devices only support a limited set of
-widthxheight sizes and framerates. You can check which are
-supported for example with the command dov4l for Video4Linux
-devices and using -list_formats all for Video4Linux2 devices.
-
-
If the size for the device is set to 0x0, the input device will
-try to auto-detect the size to use.
-Only for the video4linux2 device, if the frame rate is set to 0/0 the
-input device will use the frame rate value already set in the driver.
-
-
Video4Linux support is deprecated since Linux 2.6.30, and will be
-dropped in later versions.
-
-
Note that if FFmpeg is build with v4l-utils support ("–enable-libv4l2"
-option), it will always be used.
-
-
Follow some usage examples of the video4linux devices with the ff*
-tools.
-
# Grab and show the input of a video4linux device, frame rate is set
-# to the default of 25/1.
-ffplay -s 320x240 -f video4linux /dev/video0
-
-# Grab and show the input of a video4linux2 device, auto-adjust size.
-ffplay -f video4linux2 /dev/video0
-
-# Grab and record the input of a video4linux2 device, auto-adjust size,
-# frame rate value defaults to 0/0 so it is read from the video4linux2
-# driver.
-ffmpeg -f video4linux2 -i /dev/video0 out.mpeg
-
-
-
"v4l" and "v4l2" can be used as aliases for the respective "video4linux" and
-"video4linux2".
-
The filename passed as input is the capture driver number, ranging from
-0 to 9. You may use "list" as filename to print a list of drivers. Any
-other filename will be interpreted as device number 0.
-
hostname:display_number.screen_number specifies the
-X11 display name of the screen to grab from. hostname can be
-omitted, and defaults to "localhost". The environment variable
-DISPLAY contains the default display name.
-
-
x_offset and y_offset specify the offsets of the grabbed
-area with respect to the top-left border of the X11 screen. They
-default to 0.
-
-
Check the X11 documentation (e.g. man X) for more detailed information.
-
-
Use the dpyinfo program for getting basic information about the
-properties of your X11 display (e.g. grep for "name" or "dimensions").
-
When it is specified with "centered", the grabbing region follows the mouse
-pointer and keeps the pointer at the center of region; otherwise, the region
-follows only when the mouse pointer reaches within PIXELS (greater than
-zero) to the edge of region.
-
-
For example:
-
ffmpeg -f x11grab -follow_mouse centered -r 25 -s cif -i :0.0 out.mpg
-
-# Follows only when the mouse pointer reaches within 100 pixels to edge
-ffmpeg -f x11grab -follow_mouse 100 -r 25 -s cif -i :0.0 out.mpg
-
If show_region AVOption is specified with 1, then the grabbing
-region will be indicated on screen. With this option, it’s easy to know what is
-being grabbed if only a portion of the screen is grabbed.
-
Output devices are configured elements in FFmpeg which allow to write
-multimedia data to an output device attached to your system.
-
-
When you configure your FFmpeg build, all the supported output devices
-are enabled by default. You can list all available ones using the
-configure option "–list-outdevs".
-
-
You can disable all the output devices using the configure option
-"–disable-outdevs", and selectively enable an output device using the
-option "–enable-outdev=OUTDEV", or you can disable a particular
-input device using the option "–disable-outdev=OUTDEV".
-
-
The option "-formats" of the ff* tools will display the list of
-enabled output devices (amongst the muxers).
-
-
A description of the currently available output devices follows.
-
This output devices allows to show a video stream in an SDL
-window. Only one SDL window is allowed per application, so you can
-have only one instance of this output device in an application.
-
-
To enable this output device you need libsdl installed on your system
-when configuring your build.
-
Set the SDL window title, if not specified default to the filename
-specified for the output device.
-
-
-
‘icon_title’
-
Set the name of the iconified SDL window, if not specified it is set
-to the same value of window_title.
-
-
-
‘window_size’
-
Set the SDL window size, can be a string of the form
-widthxheight or a video size abbreviation.
-If not specified it defaults to the size of the input video.
-
Protocols are configured elements in FFmpeg which allow to access
-resources which require the use of a particular protocol.
-
-
When you configure your FFmpeg build, all the supported protocols are
-enabled by default. You can list all available ones using the
-configure option "–list-protocols".
-
-
You can disable all the protocols using the configure option
-"–disable-protocols", and selectively enable a protocol using the
-option "–enable-protocol=PROTOCOL", or you can disable a
-particular protocol using the option
-"–disable-protocol=PROTOCOL".
-
-
The option "-protocols" of the ff* tools will display the list of
-supported protocols.
-
-
A description of the currently available protocols follows.
-
Read Apple HTTP Live Streaming compliant segmented stream as
-a uniform one. The M3U8 playlists describing the segments can be
-remote HTTP resources or local files, accessed using the standard
-file protocol.
-HTTP is default, specific protocol can be declared by specifying
-"+proto" after the applehttp URI scheme name, where proto
-is either "file" or "http".
-
Computes the MD5 hash of the data to be written, and on close writes
-this to the designated output or stdout if none is specified. It can
-be used to test muxers without writing an actual file.
-
-
Some examples follow.
-
# Write the MD5 hash of the encoded AVI file to the file output.avi.md5.
-ffmpeg -i input.flv -f avi -y md5:output.avi.md5
-
-# Write the MD5 hash of the encoded AVI file to stdout.
-ffmpeg -i input.flv -f avi -y md5:
-
-
-
Note that some formats (typically MOV) require the output protocol to
-be seekable, so they will fail with the MD5 output protocol.
-
number is the number corresponding to the file descriptor of the
-pipe (e.g. 0 for stdin, 1 for stdout, 2 for stderr). If number
-is not specified, by default the stdout file descriptor will be used
-for writing, stdin for reading.
-
-
For example to read from stdin with ffmpeg:
-
cat test.wav | ffmpeg -i pipe:0
-# ...this is the same as...
-cat test.wav | ffmpeg -i pipe:
-
-
-
For writing to stdout with ffmpeg:
-
ffmpeg -i test.wav -f avi pipe:1 | cat > test.avi
-# ...this is the same as...
-ffmpeg -i test.wav -f avi pipe: | cat > test.avi
-
-
-
Note that some formats (typically MOV), require the output protocol to
-be seekable, so they will fail with the pipe output protocol.
-
The Real-Time Messaging Protocol (RTMP) is used for streaming multimedia
-content across a TCP/IP network.
-
-
The required syntax is:
-
rtmp://server[:port][/app][/playpath]
-
-
-
The accepted parameters are:
-
-
‘server’
-
The address of the RTMP server.
-
-
-
‘port’
-
The number of the TCP port to use (by default is 1935).
-
-
-
‘app’
-
It is the name of the application to access. It usually corresponds to
-the path where the application is installed on the RTMP server
-(e.g. ‘/ondemand/’, ‘/flash/live/’, etc.).
-
-
-
‘playpath’
-
It is the path or name of the resource to play with reference to the
-application specified in app, may be prefixed by "mp4:".
-
-
-
-
-
For example to read with ffplay a multimedia resource named
-"sample" from the application "vod" from an RTMP server "myserver":
-
Real-Time Messaging Protocol and its variants supported through
-librtmp.
-
-
Requires the presence of the librtmp headers and library during
-configuration. You need to explicitly configure the build with
-"–enable-librtmp". If enabled this will replace the native RTMP
-protocol.
-
-
This protocol provides most client functions and a few server
-functions needed to support RTMP, RTMP tunneled in HTTP (RTMPT),
-encrypted RTMP (RTMPE), RTMP over SSL/TLS (RTMPS) and tunneled
-variants of these encrypted types (RTMPTE, RTMPTS).
-
where rtmp_proto is one of the strings "rtmp", "rtmpt", "rtmpe",
-"rtmps", "rtmpte", "rtmpts" corresponding to each RTMP variant, and
-server, port, app and playpath have the same
-meaning as specified for the RTMP native protocol.
-options contains a list of space-separated options of the form
-key=val.
-
-
See the librtmp manual page (man 3 librtmp) for more information.
-
-
For example, to stream a file in real-time to an RTMP server using
-ffmpeg:
-
RTSP is not technically a protocol handler in libavformat, it is a demuxer
-and muxer. The demuxer supports both normal RTSP (with data transferred
-over RTP; this is used by e.g. Apple and Microsoft) and Real-RTSP (with
-data transferred over RDT).
-
-
The muxer can be used to send a stream using RTSP ANNOUNCE to a server
-supporting it (currently Darwin Streaming Server and Mischa Spiegelmock’s
-RTSP server).
-
-
The required syntax for a RTSP url is:
-
rtsp://hostname[:port]/path
-
-
-
The following options (set on the ffmpeg/ffplay command
-line, or set in code via AVOptions or in avformat_open_input),
-are supported:
-
-
Flags for rtsp_transport:
-
-
-
‘udp’
-
Use UDP as lower transport protocol.
-
-
-
‘tcp’
-
Use TCP (interleaving within the RTSP control channel) as lower
-transport protocol.
-
-
-
‘udp_multicast’
-
Use UDP multicast as lower transport protocol.
-
-
-
‘http’
-
Use HTTP tunneling as lower transport protocol, which is useful for
-passing proxies.
-
-
-
-
Multiple lower transport protocols may be specified, in that case they are
-tried one at a time (if the setup of one fails, the next one is tried).
-For the muxer, only the tcp and udp options are supported.
-
-
Flags for rtsp_flags:
-
-
-
‘filter_src’
-
Accept packets only from negotiated peer address and port.
-
-
-
-
When receiving data over UDP, the demuxer tries to reorder received packets
-(since they may arrive out of order, or packets may get lost totally). In
-order for this to be enabled, a maximum delay must be specified in the
-max_delay field of AVFormatContext.
-
-
When watching multi-bitrate Real-RTSP streams with ffplay, the
-streams to display can be chosen with -vstn and
--astn for video and audio respectively, and can be switched
-on the fly by pressing v and a.
-
-
Example command lines:
-
-
To watch a stream over UDP, with a max reordering delay of 0.5 seconds:
-
Session Announcement Protocol (RFC 2974). This is not technically a
-protocol handler in libavformat, it is a muxer and demuxer.
-It is used for signalling of RTP streams, by announcing the SDP for the
-streams regularly on a separate port.
-
The RTP packets are sent to destination on port port,
-or to port 5004 if no port is specified.
-options is a &-separated list. The following options
-are supported:
-
-
-
‘announce_addr=address’
-
Specify the destination IP address for sending the announcements to.
-If omitted, the announcements are sent to the commonly used SAP
-announcement multicast address 224.2.127.254 (sap.mcast.net), or
-ff0e::2:7ffe if destination is an IPv6 address.
-
-
-
‘announce_port=port’
-
Specify the port to send the announcements on, defaults to
-9875 if not specified.
-
-
-
‘ttl=ttl’
-
Specify the time to live value for the announcements and RTP packets,
-defaults to 255.
-
-
-
‘same_port=0|1’
-
If set to 1, send all RTP streams on the same port pair. If zero (the
-default), all streams are sent on unique ports, with each stream on a
-port 2 numbers higher than the previous.
-VLC/Live555 requires this to be set to 1, to be able to receive the stream.
-The RTP stack in libavformat for receiving requires all streams to be sent
-on unique ports.
-
-
-
-
Example command lines follow.
-
-
To broadcast a stream on the local subnet, for watching in VLC:
-
-
ffmpeg -re -i input -f sap sap://224.0.0.255?same_port=1
-
-
-
Similarly, for watching in ffplay:
-
-
ffmpeg -re -i input -f sap sap://224.0.0.255
-
-
-
And for watching in ffplay, over IPv6:
-
-
ffmpeg -re -i input -f sap sap://[ff0e::1:2:3:4]
-
The syntax for a SAP url given to the demuxer is:
-
sap://[address][:port]
-
-
-
address is the multicast address to listen for announcements on,
-if omitted, the default 224.2.127.254 (sap.mcast.net) is used. port
-is the port that is listened on, 9875 if omitted.
-
-
The demuxers listens for announcements on the given address and port.
-Once an announcement is received, it tries to receive that particular stream.
-
-
Example command lines follow.
-
-
To play back the first stream announced on the normal SAP multicast address:
-
-
ffplay sap://
-
-
-
To play back the first stream announced on one the default IPv6 SAP multicast address:
-
options contains a list of &-seperated options of the form key=val.
-Follow the list of supported options.
-
-
-
‘buffer_size=size’
-
set the UDP buffer size in bytes
-
-
-
‘localport=port’
-
override the local UDP port to bind with
-
-
-
‘localaddr=addr’
-
Choose the local IP address. This is useful e.g. if sending multicast
-and the host has multiple interfaces, where the user can choose
-which interface to send on by specifying the IP address of that interface.
-
-
-
‘pkt_size=size’
-
set the size in bytes of UDP packets
-
-
-
‘reuse=1|0’
-
explicitly allow or disallow reusing UDP sockets
-
-
-
‘ttl=ttl’
-
set the time to live value (for multicast only)
-
-
-
‘connect=1|0’
-
Initialize the UDP socket with connect(). In this case, the
-destination address can’t be changed with ff_udp_set_remote_url later.
-If the destination address isn’t known at the start, this option can
-be specified in ff_udp_set_remote_url, too.
-This allows finding out the source address for the packets with getsockname,
-and makes writes return with AVERROR(ECONNREFUSED) if "destination
-unreachable" is received.
-For receiving, this gives the benefit of only receiving packets from
-the specified peer address/port.
-
-
-
-
Some usage examples of the udp protocol with ffmpeg follow.
-
-
To stream over UDP to a remote endpoint:
-
ffmpeg -i input -f format udp://hostname:port
-
-
-
To stream in mpegts format over UDP using 188 sized UDP packets, using a large input buffer:
-
When you configure your FFmpeg build, all the supported bitstream
-filters are enabled by default. You can list all available ones using
-the configure option --list-bsfs.
-
-
You can disable all the bitstream filters using the configure option
---disable-bsfs, and selectively enable any bitstream filter using
-the option --enable-bsf=BSF, or you can disable a particular
-bitstream filter using the option --disable-bsf=BSF.
-
-
The option -bsfs of the ff* tools will display the list of
-all the supported bitstream filters included in your build.
-
-
Below is a description of the currently available bitstream filters.
-
Avery Lee, writing in the rec.video.desktop newsgroup in 2001,
-commented that "MJPEG, or at least the MJPEG in AVIs having the
-MJPG fourcc, is restricted JPEG with a fixed – and *omitted* –
-Huffman table. The JPEG must be YCbCr colorspace, it must be 4:2:2,
-and it must use basic Huffman encoding, not arithmetic or
-progressive. . . . You can indeed extract the MJPEG frames and
-decode them with a regular JPEG decoder, but you have to prepend
-the DHT segment to them, or else the decoder won’t have any idea
-how to decompress the data. The exact table necessary is given in
-the OpenDML spec."
-
-
This bitstream filter patches the header of frames extracted from an MJPEG
-stream (carrying the AVI1 header ID and lacking a DHT segment) to
-produce fully qualified JPEG images.
-
A filtergraph is a directed graph of connected filters. It can contain
-cycles, and there can be multiple links between a pair of
-filters. Each link has one input pad on one side connecting it to one
-filter from which it takes its input, and one output pad on the other
-side connecting it to the one filter accepting its output.
-
-
Each filter in a filtergraph is an instance of a filter class
-registered in the application, which defines the features and the
-number of input and output pads of the filter.
-
-
A filter with no input pads is called a "source", a filter with no
-output pads is called a "sink".
-
A filtergraph can be represented using a textual representation, which
-is recognized by the -vf option of the ff*
-tools, and by the avfilter_graph_parse() function defined in
-‘libavfilter/avfiltergraph.h’.
-
-
A filterchain consists of a sequence of connected filters, each one
-connected to the previous one in the sequence. A filterchain is
-represented by a list of ","-separated filter descriptions.
-
-
A filtergraph consists of a sequence of filterchains. A sequence of
-filterchains is represented by a list of ";"-separated filterchain
-descriptions.
-
-
A filter is represented by a string of the form:
-[in_link_1]...[in_link_N]filter_name=arguments[out_link_1]...[out_link_M]
-
-
filter_name is the name of the filter class of which the
-described filter is an instance of, and has to be the name of one of
-the filter classes registered in the program.
-The name of the filter class is optionally followed by a string
-"=arguments".
-
-
arguments is a string which contains the parameters used to
-initialize the filter instance, and are described in the filter
-descriptions below.
-
-
The list of arguments can be quoted using the character "’" as initial
-and ending mark, and the character ’\’ for escaping the characters
-within the quoted text; otherwise the argument string is considered
-terminated when the next special character (belonging to the set
-"[]=;,") is encountered.
-
-
The name and arguments of the filter are optionally preceded and
-followed by a list of link labels.
-A link label allows to name a link and associate it to a filter output
-or input pad. The preceding labels in_link_1
-... in_link_N, are associated to the filter input pads,
-the following labels out_link_1 ... out_link_M, are
-associated to the output pads.
-
-
When two link labels with the same name are found in the
-filtergraph, a link between the corresponding input and output pad is
-created.
-
-
If an output pad is not labelled, it is linked by default to the first
-unlabelled input pad of the next filter in the filterchain.
-For example in the filterchain:
-
nullsrc, split[L1], [L2]overlay, nullsink
-
-
the split filter instance has two output pads, and the overlay filter
-instance two input pads. The first output pad of split is labelled
-"L1", the first input pad of overlay is labelled "L2", and the second
-output pad of split is linked to the second input pad of overlay,
-which are both unlabelled.
-
-
In a complete filterchain all the unlabelled filter input and output
-pads must be connected. A filtergraph is considered valid if all the
-filter input and output pads of all the filterchains are connected.
-
-
Follows a BNF description for the filtergraph syntax:
-
NAME ::= sequence of alphanumeric characters and '_'
-LINKLABEL ::= "[" NAME "]"
-LINKLABELS ::= LINKLABEL [LINKLABELS]
-FILTER_ARGUMENTS ::= sequence of chars (eventually quoted)
-FILTER ::= [LINKNAMES] NAME ["=" ARGUMENTS] [LINKNAMES]
-FILTERCHAIN ::= FILTER [,FILTERCHAIN]
-FILTERGRAPH ::= FILTERCHAIN [;FILTERGRAPH]
-
When you configure your FFmpeg build, you can disable any of the
-existing filters using --disable-filters.
-The configure output will show the audio filters included in your
-build.
-
-
Below is a description of the currently available audio filters.
-
Merge two audio streams into a single multi-channel stream.
-
-
This filter does not need any argument.
-
-
If the channel layouts of the inputs are disjoint, and therefore compatible,
-the channel layout of the output will be set accordingly and the channels
-will be reordered as necessary. If the channel layouts of the inputs are not
-disjoint, the output will have all the channels of the first input then all
-the channels of the second input, in that order, and the channel layout of
-the output will be the default value corresponding to the total number of
-channels.
-
-
For example, if the first input is in 2.1 (FL+FR+LF) and the second input
-is FC+BL+BR, then the output will be in 5.1, with the channels in the
-following order: a1, a2, b1, a3, b2, b3 (a1 is the first channel of the
-first input, b1 is the first channel of the second input).
-
-
On the other hand, if both input are in stereo, the output channels will be
-in the default order: a1, a2, b1, b2, and the channel layout will be
-arbitrarily set to 4.0, which may or may not be the expected value.
-
-
Both inputs must have the same sample rate, format and packing.
-
-
If inputs do not have the same duration, the output will stop with the
-shortest.
-
-
Example: merge two mono files into a stereo stream:
-
Resample the input audio to the specified sample rate.
-
-
The filter accepts exactly one parameter, the output sample rate. If not
-specified then the filter will automatically convert between its input
-and output sample rates.
-
-
For example, to resample the input audio to 44100Hz:
-
Show a line containing various information for each input audio frame.
-The input audio is not modified.
-
-
The shown line contains a sequence of key/value pairs of the form
-key:value.
-
-
A description of each shown parameter follows:
-
-
-
‘n’
-
sequential number of the input frame, starting from 0
-
-
-
‘pts’
-
presentation TimeStamp of the input frame, expressed as a number of
-time base units. The time base unit depends on the filter input pad, and
-is usually 1/sample_rate.
-
-
-
‘pts_time’
-
presentation TimeStamp of the input frame, expressed as a number of
-seconds
-
-
-
‘pos’
-
position of the frame in the input stream, -1 if this information in
-unavailable and/or meaningless (for example in case of synthetic audio)
-
-
-
‘fmt’
-
sample format name
-
-
-
‘chlayout’
-
channel layout description
-
-
-
‘nb_samples’
-
number of samples (per each channel) contained in the filtered frame
-
-
-
‘rate’
-
sample rate for the audio frame
-
-
-
‘planar’
-
if the packing format is planar, 0 if packed
-
-
-
‘checksum’
-
Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame
-
-
-
‘plane_checksum’
-
Adler-32 checksum (printed in hexadecimal) for each input frame plane,
-expressed in the form "[c0c1c2c3c4c5
-c6c7]"
-
Forward two audio streams and control the order the buffers are forwarded.
-
-
The argument to the filter is an expression deciding which stream should be
-forwarded next: if the result is negative, the first stream is forwarded; if
-the result is positive or zero, the second stream is forwarded. It can use
-the following variables:
-
-
-
b1 b2
-
number of buffers forwarded so far on each stream
-
-
s1 s2
-
number of samples forwarded so far on each stream
-
-
t1 t2
-
current timestamp of each stream
-
-
-
-
The default value is t1-t2, which means to always forward the stream
-that has a smaller timestamp.
-
-
Example: stress-test amerge by randomly sending buffers on the wrong
-input, while avoiding too much of a desynchronization:
-
This filter adds ‘cues’ to 44.1kHz stereo (i.e. audio CD format) audio
-so that when listened to on headphones the stereo image is moved from
-inside your head (standard for headphones) to outside and in front of
-the listener (standard for speakers).
-
Mix channels with specific gain levels. The filter accepts the output
-channel layout followed by a set of channels definitions.
-
-
This filter is also designed to remap efficiently the channels of an audio
-stream.
-
-
The filter accepts parameters of the form:
-"l:outdef:outdef:..."
-
-
-
‘l’
-
output channel layout or number of channels
-
-
-
‘outdef’
-
output channel specification, of the form:
-"out_name=[gain*]in_name[+[gain*]in_name...]"
-
-
-
‘out_name’
-
output channel to define, either a channel name (FL, FR, etc.) or a channel
-number (c0, c1, etc.)
-
-
-
‘gain’
-
multiplicative coefficient for the channel, 1 leaving the volume unchanged
-
-
-
‘in_name’
-
input channel to use, see out_name for details; it is not possible to mix
-named and numbered input channels
-
-
-
-
If the ‘=’ in a channel specification is replaced by ‘<’, then the gains for
-that specification will be renormalized so that the total is 1, thus
-avoiding clipping noise.
-
Note that ffmpeg integrates a default down-mix (and up-mix) system
-that should be preferred (see "-ac" option) unless you have very specific
-needs.
-
The channel remapping will be effective if, and only if:
-
-
-
gain coefficients are zeroes or ones,
-
only one input per channel output,
-
the number of output channels is supported by libswresample (16 at the
- moment)
-
-
-
If all these conditions are satisfied, the filter will notify the user ("Pure
-channel mapping detected"), and use an optimized and lossless method to do the
-remapping.
-
-
For example, if you have a 5.1 source and want a stereo audio stream by
-dropping the extra channels:
-
pan="stereo: c0=FL : c1=FR"
-
-
-
Given the same source, you can also switch front left and front right channels
-and keep the input channel layout:
-
This filter logs a message when it detects that the input audio volume is less
-or equal to a noise tolerance value for a duration greater or equal to the
-minimum detected noise duration.
-
-
The printed times and duration are expressed in seconds.
-
-
-
‘duration, d’
-
Set silence duration until notification (default is 2 seconds).
-
-
-
‘noise, n’
-
Set noise tolerance. Can be specified in dB (in case "dB" is appended to the
-specified value) or amplitude ratio. Default is -60dB, or 0.001.
-
-
-
-
Detect 5 seconds of silence with -50dB noise tolerance:
-
silencedetect=n=-50dB:d=5
-
-
-
Complete example with ffmpeg to detect silence with 0.0001 noise
-tolerance in ‘silence.mp3’:
-
The filter accepts exactly one parameter vol, which expresses
-how the audio volume will be increased or decreased.
-
-
Output values are clipped to the maximum value.
-
-
If vol is expressed as a decimal number, the output audio
-volume is given by the relation:
-
output_volume = vol * input_volume
-
-
-
If vol is expressed as a decimal number followed by the string
-"dB", the value represents the requested change in decibels of the
-input audio power, and the output audio volume is given by the
-relation:
-
output_volume = 10^(vol/20) * input_volume
-
-
-
Otherwise vol is considered an expression and its evaluated
-value is used for computing the output audio volume according to the
-first relation.
-
Buffer audio frames, and make them available to the filter chain.
-
-
This source is mainly intended for a programmatic use, in particular
-through the interface defined in ‘libavfilter/asrc_abuffer.h’.
-
-
It accepts the following mandatory parameters:
-sample_rate:sample_fmt:channel_layout:packing
-
-
-
‘sample_rate’
-
The sample rate of the incoming audio buffers.
-
-
-
‘sample_fmt’
-
The sample format of the incoming audio buffers.
-Either a sample format name or its corresponging integer representation from
-the enum AVSampleFormat in ‘libavutil/samplefmt.h’
-
-
-
‘channel_layout’
-
The channel layout of the incoming audio buffers.
-Either a channel layout name from channel_layout_map in
-‘libavutil/audioconvert.c’ or its corresponding integer representation
-from the AV_CH_LAYOUT_* macros in ‘libavutil/audioconvert.h’
-
-
-
‘packing’
-
Either "packed" or "planar", or their integer representation: 0 or 1
-respectively.
-
-
-
-
-
For example:
-
abuffer=44100:s16:stereo:planar
-
-
-
will instruct the source to accept planar 16bit signed stereo at 44100Hz.
-Since the sample format with name "s16" corresponds to the number
-1 and the "stereo" channel layout corresponds to the value 3, this is
-equivalent to:
-
Generate an audio signal specified by an expression.
-
-
This source accepts in input one or more expressions (one for each
-channel), which are evaluated and used to generate a corresponding
-audio signal.
-
-
It accepts the syntax: exprs[::options].
-exprs is a list of expressions separated by ":", one for each
-separate channel. The output channel layout depends on the number of
-provided expressions, up to 8 channels are supported.
-
-
options is an optional sequence of key=value pairs,
-separated by ":".
-
-
The description of the accepted options follows.
-
-
-
‘duration, d’
-
Set the minimum duration of the sourced audio. See the function
-av_parse_time() for the accepted format.
-Note that the resulting duration may be greater than the specified
-duration, as the generated audio is always cut at the end of a
-complete frame.
-
-
If not specified, or the expressed duration is negative, the audio is
-supposed to be generated forever.
-
-
-
‘nb_samples, n’
-
Set the number of samples per channel per each output frame,
-default to 1024.
-
-
-
‘sample_rate, s’
-
Specify the sample rate, default to 44100.
-
-
-
-
Each expression in exprs can contain the following constants:
-
-
-
‘n’
-
number of the evaluated sample, starting from 0
-
-
-
‘t’
-
time of the evaluated sample expressed in seconds, starting from 0
-
It accepts the syntax: movie_name[:options] where
-movie_name is the name of the resource to read (not necessarily
-a file but also a device or a stream accessed through some protocol),
-and options is an optional sequence of key=value
-pairs, separated by ":".
-
-
The description of the accepted options follows.
-
-
-
‘format_name, f’
-
Specify the format assumed for the movie to read, and can be either
-the name of a container or an input device. If not specified the
-format is guessed from movie_name or by probing.
-
-
-
‘seek_point, sp’
-
Specify the seek point in seconds, the frames will be output
-starting from this seek point, the parameter is evaluated with
-av_strtod so the numerical value may be suffixed by an IS
-postfix. Default value is "0".
-
-
-
‘stream_index, si’
-
Specify the index of the audio stream to read. If the value is -1,
-the best suited audio stream will be automatically selected. Default
-value is "-1".
-
Null audio source, return unprocessed audio frames. It is mainly useful
-as a template and to be employed in analysis / debugging tools, or as
-the source for filters which ignore the input data (for example the sox
-synth filter).
-
-
It accepts an optional sequence of key=value pairs,
-separated by ":".
-
-
The description of the accepted options follows.
-
-
-
‘sample_rate, s’
-
Specify the sample rate, and defaults to 44100.
-
-
-
‘channel_layout, cl’
-
-
Specify the channel layout, and can be either an integer or a string
-representing a channel layout. The default value of channel_layout
-is "stereo".
-
-
Check the channel_layout_map definition in
-‘libavcodec/audioconvert.c’ for the mapping between strings and
-channel layout values.
-
-
-
‘nb_samples, n’
-
Set the number of samples per requested frames.
-
-
-
-
-
Follow some examples:
-
# set the sample rate to 48000 Hz and the channel layout to AV_CH_LAYOUT_MONO.
-anullsrc=r=48000:cl=4
-
-# same as
-anullsrc=r=48000:cl=mono
-
Buffer audio frames, and make them available to the end of filter chain.
-
-
This sink is mainly intended for programmatic use, in particular
-through the interface defined in ‘libavfilter/buffersink.h’.
-
-
It requires a pointer to an AVABufferSinkContext structure, which
-defines the incoming buffers’ formats, to be passed as the opaque
-parameter to avfilter_init_filter for initialization.
-
When you configure your FFmpeg build, you can disable any of the
-existing filters using --disable-filters.
-The configure output will show the video filters included in your
-build.
-
-
Below is a description of the currently available video filters.
-
Detect frames that are (almost) completely black. Can be useful to
-detect chapter transitions or commercials. Output lines consist of
-the frame number of the detected frame, the percentage of blackness,
-the position in the file if known or -1 and the timestamp in seconds.
-
-
In order to display the output lines, you need to set the loglevel at
-least to the AV_LOG_INFO value.
-
-
The filter accepts the syntax:
-
blackframe[=amount:[threshold]]
-
-
-
amount is the percentage of the pixels that have to be below the
-threshold, and defaults to 98.
-
-
threshold is the threshold below which a pixel value is
-considered black, and defaults to 32.
-
This filter accepts the parameters:
-luma_radius:luma_power:chroma_radius:chroma_power:alpha_radius:alpha_power
-
-
Chroma and alpha parameters are optional, if not specified they default
-to the corresponding values set for luma_radius and
-luma_power.
-
-
luma_radius, chroma_radius, and alpha_radius represent
-the radius in pixels of the box used for blurring the corresponding
-input plane. They are expressions, and can contain the following
-constants:
-
-
‘w, h’
-
the input width and height in pixels
-
-
-
‘cw, ch’
-
the input chroma image width and height in pixels
-
-
-
‘hsub, vsub’
-
horizontal and vertical chroma subsample values. For example for the
-pixel format "yuv422p" hsub is 2 and vsub is 1.
-
-
-
-
The radius must be a non-negative number, and must not be greater than
-the value of the expression min(w,h)/2 for the luma and alpha planes,
-and of min(cw,ch)/2 for the chroma planes.
-
-
luma_power, chroma_power, and alpha_power represent
-how many times the boxblur filter is applied to the corresponding
-plane.
-
-
Some examples follow:
-
-
-
-Apply a boxblur filter with luma, chroma, and alpha radius
-set to 2:
-
boxblur=2:1
-
-
-
-Set luma radius to 2, alpha and chroma radius to 0
-
boxblur=2:1:0:0:0:0
-
-
-
-Set luma and chroma radius to a fraction of the video dimension
-
The parameters are expressions containing the following constants:
-
-
-
‘x, y’
-
the computed values for x and y. They are evaluated for
-each new frame.
-
-
-
‘in_w, in_h’
-
the input width and height
-
-
-
‘iw, ih’
-
same as in_w and in_h
-
-
-
‘out_w, out_h’
-
the output (cropped) width and height
-
-
-
‘ow, oh’
-
same as out_w and out_h
-
-
-
‘a’
-
same as iw / ih
-
-
-
‘sar’
-
input sample aspect ratio
-
-
-
‘dar’
-
input display aspect ratio, it is the same as (iw / ih) * sar
-
-
-
‘hsub, vsub’
-
horizontal and vertical chroma subsample values. For example for the
-pixel format "yuv422p" hsub is 2 and vsub is 1.
-
-
-
‘n’
-
the number of input frame, starting from 0
-
-
-
‘pos’
-
the position in the file of the input frame, NAN if unknown
-
-
-
‘t’
-
timestamp expressed in seconds, NAN if the input timestamp is unknown
-
-
-
-
-
The out_w and out_h parameters specify the expressions for
-the width and height of the output (cropped) video. They are
-evaluated just at the configuration of the filter.
-
-
The default value of out_w is "in_w", and the default value of
-out_h is "in_h".
-
-
The expression for out_w may depend on the value of out_h,
-and the expression for out_h may depend on out_w, but they
-cannot depend on x and y, as x and y are
-evaluated after out_w and out_h.
-
-
The x and y parameters specify the expressions for the
-position of the top-left corner of the output (non-cropped) area. They
-are evaluated for each frame. If the evaluated value is not valid, it
-is approximated to the nearest valid value.
-
-
The default value of x is "(in_w-out_w)/2", and the default
-value for y is "(in_h-out_h)/2", which set the cropped area at
-the center of the input image.
-
-
The expression for x may depend on y, and the expression
-for y may depend on x.
-
-
Follow some examples:
-
# crop the central input area with size 100x100
-crop=100:100
-
-# crop the central input area with size 2/3 of the input video
-"crop=2/3*in_w:2/3*in_h"
-
-# crop the input video central square
-crop=in_h
-
-# delimit the rectangle with the top-left corner placed at position
-# 100:100 and the right-bottom corner corresponding to the right-bottom
-# corner of the input image.
-crop=in_w-100:in_h-100:100:100
-
-# crop 10 pixels from the left and right borders, and 20 pixels from
-# the top and bottom borders
-"crop=in_w-2*10:in_h-2*20"
-
-# keep only the bottom right quarter of the input image
-"crop=in_w/2:in_h/2:in_w/2:in_h/2"
-
-# crop height for getting Greek harmony
-"crop=in_w:1/PHI*in_w"
-
-# trembling effect
-"crop=in_w/2:in_h/2:(in_w-out_w)/2+((in_w-out_w)/2)*sin(n/10):(in_h-out_h)/2 +((in_h-out_h)/2)*sin(n/7)"
-
-# erratic camera effect depending on timestamp
-"crop=in_w/2:in_h/2:(in_w-out_w)/2+((in_w-out_w)/2)*sin(t*10):(in_h-out_h)/2 +((in_h-out_h)/2)*sin(t*13)"
-
-# set x depending on the value of y
-"crop=in_w/2:in_h/2:y:10+10*sin(n/10)"
-
Calculate necessary cropping parameters and prints the recommended
-parameters through the logging system. The detected dimensions
-correspond to the non-black area of the input video.
-
-
It accepts the syntax:
-
cropdetect[=limit[:round[:reset]]]
-
-
-
-
‘limit’
-
Threshold, which can be optionally specified from nothing (0) to
-everything (255), defaults to 24.
-
-
-
‘round’
-
Value which the width/height should be divisible by, defaults to
-16. The offset is automatically adjusted to center the video. Use 2 to
-get only even dimensions (needed for 4:2:2 video). 16 is best when
-encoding to most video codecs.
-
-
-
‘reset’
-
Counter that determines after how many frames cropdetect will reset
-the previously detected largest video area and start over to detect
-the current optimal crop area. Defaults to 0.
-
-
This can be useful when channel logos distort the video area. 0
-indicates never reset and return the largest area encountered during
-playback.
-
Suppress a TV station logo by a simple interpolation of the surrounding
-pixels. Just set a rectangle covering the logo and watch it disappear
-(and sometimes something even uglier appear - your mileage may vary).
-
-
The filter accepts parameters as a string of the form
-"x:y:w:h:band", or as a list of
-key=value pairs, separated by ":".
-
-
The description of the accepted parameters follows.
-
-
-
‘x, y’
-
Specify the top left corner coordinates of the logo. They must be
-specified.
-
-
-
‘w, h’
-
Specify the width and height of the logo to clear. They must be
-specified.
-
-
-
‘band, t’
-
Specify the thickness of the fuzzy edge of the rectangle (added to
-w and h). The default value is 4.
-
-
-
‘show’
-
When set to 1, a green rectangle is drawn on the screen to simplify
-finding the right x, y, w, h parameters, and
-band is set to 4. The default value is 0.
-
-
-
-
-
Some examples follow.
-
-
-
-Set a rectangle covering the area with top left corner coordinates 0,0
-and size 100x77, setting a band of size 10:
-
delogo=0:0:100:77:10
-
-
-
-As the previous example, but use named options:
-
Attempt to fix small changes in horizontal and/or vertical shift. This
-filter helps remove camera shake from hand-holding a camera, bumping a
-tripod, moving on a vehicle, etc.
-
-
The filter accepts parameters as a string of the form
-"x:y:w:h:rx:ry:edge:blocksize:contrast:search:filename"
-
-
A description of the accepted parameters follows.
-
-
-
‘x, y, w, h’
-
Specify a rectangular area where to limit the search for motion
-vectors.
-If desired the search for motion vectors can be limited to a
-rectangular area of the frame defined by its top left corner, width
-and height. These parameters have the same meaning as the drawbox
-filter which can be used to visualise the position of the bounding
-box.
-
-
This is useful when simultaneous movement of subjects within the frame
-might be confused for camera motion by the motion vector search.
-
-
If any or all of x, y, w and h are set to -1
-then the full frame is used. This allows later options to be set
-without specifying the bounding box for the motion vector search.
-
-
Default - search the whole frame.
-
-
-
‘rx, ry’
-
Specify the maximum extent of movement in x and y directions in the
-range 0-64 pixels. Default 16.
-
-
-
‘edge’
-
Specify how to generate pixels to fill blanks at the edge of the
-frame. An integer from 0 to 3 as follows:
-
-
‘0’
-
Fill zeroes at blank locations
-
-
‘1’
-
Original image at blank locations
-
-
‘2’
-
Extruded edge value at blank locations
-
-
‘3’
-
Mirrored edge at blank locations
-
-
-
-
The default setting is mirror edge at blank locations.
-
-
-
‘blocksize’
-
Specify the blocksize to use for motion search. Range 4-128 pixels,
-default 8.
-
-
-
‘contrast’
-
Specify the contrast threshold for blocks. Only blocks with more than
-the specified contrast (difference between darkest and lightest
-pixels) will be considered. Range 1-255, default 125.
-
-
-
‘search’
-
Specify the search strategy 0 = exhaustive search, 1 = less exhaustive
-search. Default - exhaustive search.
-
-
-
‘filename’
-
If set then a detailed log of the motion search is written to the
-specified file.
-
Draw text string or text from specified file on top of video using the
-libfreetype library.
-
-
To enable compilation of this filter you need to configure FFmpeg with
---enable-libfreetype.
-
-
The filter also recognizes strftime() sequences in the provided text
-and expands them accordingly. Check the documentation of strftime().
-
-
The filter accepts parameters as a list of key=value pairs,
-separated by ":".
-
-
The description of the accepted parameters follows.
-
-
-
‘fontfile’
-
The font file to be used for drawing text. Path must be included.
-This parameter is mandatory.
-
-
-
‘text’
-
The text string to be drawn. The text must be a sequence of UTF-8
-encoded characters.
-This parameter is mandatory if no file is specified with the parameter
-textfile.
-
-
-
‘textfile’
-
A text file containing text to be drawn. The text must be a sequence
-of UTF-8 encoded characters.
-
-
This parameter is mandatory if no text string is specified with the
-parameter text.
-
-
If both text and textfile are specified, an error is thrown.
-
-
-
‘x, y’
-
The expressions which specify the offsets where text will be drawn
-within the video frame. They are relative to the top/left border of the
-output image.
-
-
The default value of x and y is "0".
-
-
See below for the list of accepted constants.
-
-
-
‘fontsize’
-
The font size to be used for drawing text.
-The default value of fontsize is 16.
-
-
-
‘fontcolor’
-
The color to be used for drawing fonts.
-Either a string (e.g. "red") or in 0xRRGGBB[AA] format
-(e.g. "0xff000033"), possibly followed by an alpha specifier.
-The default value of fontcolor is "black".
-
-
-
‘boxcolor’
-
The color to be used for drawing box around text.
-Either a string (e.g. "yellow") or in 0xRRGGBB[AA] format
-(e.g. "0xff00ff"), possibly followed by an alpha specifier.
-The default value of boxcolor is "white".
-
-
-
‘box’
-
Used to draw a box around text using background color.
-Value should be either 1 (enable) or 0 (disable).
-The default value of box is 0.
-
-
-
‘shadowx, shadowy’
-
The x and y offsets for the text shadow position with respect to the
-position of the text. They can be either positive or negative
-values. Default value for both is "0".
-
-
-
‘shadowcolor’
-
The color to be used for drawing a shadow behind the drawn text. It
-can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA]
-form (e.g. "0xff00ff"), possibly followed by an alpha specifier.
-The default value of shadowcolor is "black".
-
-
-
‘ft_load_flags’
-
Flags to be used for loading the fonts.
-
-
The flags map the corresponding flags supported by libfreetype, and are
-a combination of the following values:
-
-
default
-
no_scale
-
no_hinting
-
render
-
no_bitmap
-
vertical_layout
-
force_autohint
-
crop_bitmap
-
pedantic
-
ignore_global_advance_width
-
no_recurse
-
ignore_transform
-
monochrome
-
linear_design
-
no_autohint
-
end table
-
-
-
Default value is "render".
-
-
For more information consult the documentation for the FT_LOAD_*
-libfreetype flags.
-
-
-
‘tabsize’
-
The size in number of spaces to use for rendering the tab.
-Default value is 4.
-
-
-
-
The parameters for x and y are expressions containing the
-following constants:
-
-
-
‘W, H’
-
the input width and height
-
-
-
‘tw, text_w’
-
the width of the rendered text
-
-
-
‘th, text_h’
-
the height of the rendered text
-
-
-
‘lh, line_h’
-
the height of each text line
-
-
-
‘sar’
-
input sample aspect ratio
-
-
-
‘dar’
-
input display aspect ratio, it is the same as (w / h) * sar
-
-
-
‘hsub, vsub’
-
horizontal and vertical chroma subsample values. For example for the
-pixel format "yuv422p" hsub is 2 and vsub is 1.
-
-
-
‘max_glyph_w’
-
maximum glyph width, that is the maximum width for all the glyphs
-contained in the rendered text
-
-
-
‘max_glyph_h’
-
maximum glyph height, that is the maximum height for all the glyphs
-contained in the rendered text, it is equivalent to ascent -
-descent.
-
-
-
‘max_glyph_a, ascent’
-
-
the maximum distance from the baseline to the highest/upper grid
-coordinate used to place a glyph outline point, for all the rendered
-glyphs.
-It is a positive value, due to the grid’s orientation with the Y axis
-upwards.
-
-
-
‘max_glyph_d, descent’
-
the maximum distance from the baseline to the lowest grid coordinate
-used to place a glyph outline point, for all the rendered glyphs.
-This is a negative value, due to the grid’s orientation, with the Y axis
-upwards.
-
-
-
‘n’
-
the number of input frame, starting from 0
-
-
-
‘t’
-
timestamp expressed in seconds, NAN if the input timestamp is unknown
-
-
-
‘timecode’
-
initial timecode representation in "hh:mm:ss[:;.]ff" format. It can be used
-with or without text parameter. rate option must be specified.
-Note that timecode options are not effective if FFmpeg is build with
---disable-avcodec.
-
-
-
‘r, rate’
-
frame rate (timecode only)
-
-
-
-
Some examples follow.
-
-
-
-Draw "Test Text" with font FreeSerif, using the default values for the
-optional parameters.
-
-
-Draw ’Test Text’ with font FreeSerif of size 24 at position x=100
-and y=50 (counting from the top-left corner of the screen), text is
-yellow with a red box around it. Both the text and the box have an
-opacity of 20%.
-
-
-Show a text line sliding from right to left in the last row of the video
-frame. The file ‘LONG_LINE’ is assumed to contain a single line
-with no newlines.
-
It accepts the parameters:
-type:start_frame:nb_frames[:options]
-
-
type specifies if the effect type, can be either "in" for
-fade-in, or "out" for a fade-out effect.
-
-
start_frame specifies the number of the start frame for starting
-to apply the fade effect.
-
-
nb_frames specifies the number of frames for which the fade
-effect has to last. At the end of the fade-in effect the output video
-will have the same intensity as the input video, at the end of the
-fade-out transition the output video will be completely black.
-
-
options is an optional sequence of key=value pairs,
-separated by ":". The description of the accepted options follows.
-
-
-
‘type, t’
-
See type.
-
-
-
‘start_frame, s’
-
See start_frame.
-
-
-
‘nb_frames, n’
-
See nb_frames.
-
-
-
‘alpha’
-
If set to 1, fade only alpha channel, if one exists on the input.
-Default value is 0.
-
-
-
-
A few usage examples follow, usable too as test scenarios.
-
# fade in first 30 frames of video
-fade=in:0:30
-
-# fade out last 45 frames of a 200-frame video
-fade=out:155:45
-
-# fade in first 25 frames and fade out last 25 frames of a 1000-frame video
-fade=in:0:25, fade=out:975:25
-
-# make first 5 frames black, then fade in from frame 5-24
-fade=in:5:20
-
-# fade in alpha over first 25 frames of video
-fade=in:0:25:alpha=1
-
It accepts one parameter which specifies the required field order that
-the input interlaced video will be transformed to. The parameter can
-assume one of the following values:
-
-
-
‘0 or bff’
-
output bottom field first
-
-
‘1 or tff’
-
output top field first
-
-
-
-
Default value is "tff".
-
-
Transformation is achieved by shifting the picture content up or down
-by one line, and filling the remaining line with appropriate picture content.
-This method is consistent with most broadcast field order converters.
-
-
If the input video is not flagged as being interlaced, or it is already
-flagged as being of the required output field order then this filter does
-not alter the incoming video.
-
-
This filter is very useful when converting to or from PAL DV material,
-which is bottom field first.
-
Convert the input video to one of the specified pixel formats.
-Libavfilter will try to pick one that is supported for the input to
-the next filter.
-
-
The filter accepts a list of pixel format names, separated by ":",
-for example "yuv420p:monow:rgb24".
-
-
Some examples follow:
-
# convert the input video to the format "yuv420p"
-format=yuv420p
-
-# convert the input video to any of the formats in the list
-format=yuv420p:yuv444p:yuv410p
-
To enable compilation of this filter you need to install the frei0r
-header and configure FFmpeg with --enable-frei0r.
-
-
The filter supports the syntax:
-
filter_name[{:|=}param1:param2:...:paramN]
-
-
-
filter_name is the name to the frei0r effect to load. If the
-environment variable FREI0R_PATH is defined, the frei0r effect
-is searched in each one of the directories specified by the colon
-separated list in FREIOR_PATH, otherwise in the standard frei0r
-paths, which are in this order: ‘HOME/.frei0r-1/lib/’,
-‘/usr/local/lib/frei0r-1/’, ‘/usr/lib/frei0r-1/’.
-
-
param1, param2, ... , paramN specify the parameters
-for the frei0r effect.
-
-
A frei0r effect parameter can be a boolean (whose values are specified
-with "y" and "n"), a double, a color (specified by the syntax
-R/G/B, R, G, and B being float
-numbers from 0.0 to 1.0) or by an av_parse_color() color
-description), a position (specified by the syntax X/Y,
-X and Y being float numbers) and a string.
-
-
The number and kind of parameters depend on the loaded effect. If an
-effect parameter is not specified the default value is set.
-
-
Some examples follow:
-
# apply the distort0r effect, set the first two double parameters
-frei0r=distort0r:0.5:0.01
-
-# apply the colordistance effect, takes a color as first parameter
-frei0r=colordistance:0.2/0.3/0.4
-frei0r=colordistance:violet
-frei0r=colordistance:0x112233
-
-# apply the perspective effect, specify the top left and top right
-# image positions
-frei0r=perspective:0.2/0.2:0.8/0.2
-
Fix the banding artifacts that are sometimes introduced into nearly flat
-regions by truncation to 8bit color depth.
-Interpolate the gradients that should go where the bands are, and
-dither them.
-
-
This filter is designed for playback only. Do not use it prior to
-lossy compression, because compression tends to lose the dither and
-bring back the bands.
-
-
The filter takes two optional parameters, separated by ’:’:
-strength:radius
-
-
strength is the maximum amount by which the filter will change
-any one pixel. Also the threshold for detecting nearly flat
-regions. Acceptable values range from .51 to 255, default value is
-1.2, out-of-range values will be clipped to the valid range.
-
-
radius is the neighborhood to fit the gradient to. A larger
-radius makes for smoother gradients, but also prevents the filter from
-modifying the pixels near detailed regions. Acceptable values are
-8-32, default value is 16, out-of-range values will be clipped to the
-valid range.
-
High precision/quality 3d denoise filter. This filter aims to reduce
-image noise producing smooth images and making still images really
-still. It should enhance compressibility.
-
-
It accepts the following optional parameters:
-luma_spatial:chroma_spatial:luma_tmp:chroma_tmp
-
-
-
‘luma_spatial’
-
a non-negative float number which specifies spatial luma strength,
-defaults to 4.0
-
-
-
‘chroma_spatial’
-
a non-negative float number which specifies spatial chroma strength,
-defaults to 3.0*luma_spatial/4.0
-
-
-
‘luma_tmp’
-
a float number which specifies luma temporal strength, defaults to
-6.0*luma_spatial/4.0
-
-
-
‘chroma_tmp’
-
a float number which specifies chroma temporal strength, defaults to
-luma_tmp*chroma_spatial/luma_spatial
-
Compute a look-up table for binding each pixel component input value
-to an output value, and apply it to input video.
-
-
lutyuv applies a lookup table to a YUV input video, lutrgb
-to an RGB input video.
-
-
These filters accept in input a ":"-separated list of options, which
-specify the expressions used for computing the lookup table for the
-corresponding pixel component values.
-
-
The lut filter requires either YUV or RGB pixel formats in
-input, and accepts the options:
-
-
‘c0’
-
first pixel component
-
-
‘c1’
-
second pixel component
-
-
‘c2’
-
third pixel component
-
-
‘c3’
-
fourth pixel component, corresponds to the alpha component
-
-
-
-
The exact component associated to each option depends on the format in
-input.
-
-
The lutrgb filter requires RGB pixel formats in input, and
-accepts the options:
-
-
‘r’
-
red component
-
-
‘g’
-
green component
-
-
‘b’
-
blue component
-
-
‘a’
-
alpha component
-
-
-
-
The lutyuv filter requires YUV pixel formats in input, and
-accepts the options:
-
-
‘y’
-
Y/luminance component
-
-
‘u’
-
U/Cb component
-
-
‘v’
-
V/Cr component
-
-
‘a’
-
alpha component
-
-
-
-
The expressions can contain the following constants and functions:
-
-
-
‘w, h’
-
the input width and height
-
-
-
‘val’
-
input value for the pixel component
-
-
-
‘clipval’
-
the input value clipped in the minval-maxval range
-
-
-
‘maxval’
-
maximum value for the pixel component
-
-
-
‘minval’
-
minimum value for the pixel component
-
-
-
‘negval’
-
the negated value for the pixel component value clipped in the
-minval-maxval range , it corresponds to the expression
-"maxval-clipval+minval"
-
-
-
‘clip(val)’
-
the computed value in val clipped in the
-minval-maxval range
-
-
-
‘gammaval(gamma)’
-
the computed gamma correction value of the pixel component value
-clipped in the minval-maxval range, corresponds to the
-expression
-"pow((clipval-minval)/(maxval-minval)\,gamma)*(maxval-minval)+minval"
-
-
-
-
-
All expressions default to "val".
-
-
Some examples follow:
-
# negate input video
-lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
-lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
-
-# the above is the same as
-lutrgb="r=negval:g=negval:b=negval"
-lutyuv="y=negval:u=negval:v=negval"
-
-# negate luminance
-lutyuv=y=negval
-
-# remove chroma components, turns the video into a graytone image
-lutyuv="u=128:v=128"
-
-# apply a luma burning effect
-lutyuv="y=2*val"
-
-# remove green and blue components
-lutrgb="g=0:b=0"
-
-# set a constant alpha channel value on input
-format=rgba,lutrgb=a="maxval-minval/2"
-
-# correct luminance gamma by a 0.5 factor
-lutyuv=y=gammaval(0.5)
-
This filter provides a wrapper around most of the filters of
-MPlayer/MEncoder.
-
-
This wrapper is considered experimental. Some of the wrapped filters
-may not work properly and we may drop support for them, as they will
-be implemented natively into FFmpeg. Thus you should avoid
-depending on them when writing portable scripts.
-
-
The filters accepts the parameters:
-filter_name[:=]filter_params
-
-
filter_name is the name of a supported MPlayer filter,
-filter_params is a string containing the parameters accepted by
-the named filter.
-
-
The list of the currently supported filters follows:
-
-
2xsai
-
decimate
-
denoise3d
-
detc
-
dint
-
divtc
-
down3dright
-
dsize
-
eq2
-
eq
-
field
-
fil
-
fixpts
-
framestep
-
fspp
-
geq
-
harddup
-
hqdn3d
-
hue
-
il
-
ilpack
-
ivtc
-
kerndeint
-
mcdeint
-
mirror
-
noise
-
ow
-
palette
-
perspective
-
phase
-
pp7
-
pullup
-
qp
-
rectangle
-
remove-logo
-
rotate
-
sab
-
screenshot
-
smartblur
-
softpulldown
-
softskip
-
spp
-
swapuv
-
telecine
-
tile
-
tinterlace
-
unsharp
-
uspp
-
yuvcsp
-
yvu9
-
-
-
The parameter syntax and behavior for the listed filters are the same
-of the corresponding MPlayer filters. For detailed instructions check
-the "VIDEO FILTERS" section in the MPlayer manual.
-
-
Some examples follow:
-
# remove a logo by interpolating the surrounding pixels
-mp=delogo=200:200:80:20:1
-
-# adjust gamma, brightness, contrast
-mp=eq2=1.0:2:0.5
-
-# tweak hue and saturation
-mp=hue=100:-10
-
Force libavfilter not to use any of the specified pixel formats for the
-input to the next filter.
-
-
The filter accepts a list of pixel format names, separated by ":",
-for example "yuv420p:monow:rgb24".
-
-
Some examples follow:
-
# force libavfilter to use a format different from "yuv420p" for the
-# input to the vflip filter
-noformat=yuv420p,vflip
-
-# convert the input video to any of the formats not contained in the list
-noformat=yuv420p:yuv444p:yuv410p
-
Dilate an image by using a specific structuring element.
-This filter corresponds to the libopencv function cvDilate.
-
-
It accepts the parameters: struct_el:nb_iterations.
-
-
struct_el represents a structuring element, and has the syntax:
-colsxrows+anchor_xxanchor_y/shape
-
-
cols and rows represent the number of columns and rows of
-the structuring element, anchor_x and anchor_y the anchor
-point, and shape the shape for the structuring element, and
-can be one of the values "rect", "cross", "ellipse", "custom".
-
-
If the value for shape is "custom", it must be followed by a
-string of the form "=filename". The file with name
-filename is assumed to represent a binary image, with each
-printable character corresponding to a bright pixel. When a custom
-shape is used, cols and rows are ignored, the number
-or columns and rows of the read file are assumed instead.
-
-
The default value for struct_el is "3x3+0x0/rect".
-
-
nb_iterations specifies the number of times the transform is
-applied to the image, and defaults to 1.
-
-
Follow some example:
-
# use the default values
-ocv=dilate
-
-# dilate using a structuring element with a 5x5 cross, iterate two times
-ocv=dilate=5x5+2x2/cross:2
-
-# read the shape from the file diamond.shape, iterate two times
-# the file diamond.shape may contain a pattern of characters like this:
-# *
-# ***
-# *****
-# ***
-# *
-# the specified cols and rows are ignored (but not the anchor point coordinates)
-ocv=0x0+2x2/custom=diamond.shape:2
-
The filter takes the following parameters:
-type:param1:param2:param3:param4.
-
-
type is the type of smooth filter to apply, and can be one of
-the following values: "blur", "blur_no_scale", "median", "gaussian",
-"bilateral". The default value is "gaussian".
-
-
param1, param2, param3, and param4 are
-parameters whose meanings depend on smooth type. param1 and
-param2 accept integer positive values or 0, param3 and
-param4 accept float values.
-
-
The default value for param1 is 3, the default value for the
-other parameters is 0.
-
-
These parameters correspond to the parameters assigned to the
-libopencv function cvSmooth.
-
It takes two inputs and one output, the first input is the "main"
-video on which the second input is overlayed.
-
-
It accepts the parameters: x:y[:options].
-
-
x is the x coordinate of the overlayed video on the main video,
-y is the y coordinate. x and y are expressions containing
-the following parameters:
-
-
-
‘main_w, main_h’
-
main input width and height
-
-
-
‘W, H’
-
same as main_w and main_h
-
-
-
‘overlay_w, overlay_h’
-
overlay input width and height
-
-
-
‘w, h’
-
same as overlay_w and overlay_h
-
-
-
-
options is an optional list of key=value pairs,
-separated by ":".
-
-
The description of the accepted options follows.
-
-
-
‘rgb’
-
If set to 1, force the filter to accept inputs in the RGB
-color space. Default value is 0.
-
-
-
-
Be aware that frames are taken from each input video in timestamp
-order, hence, if their initial timestamps differ, it is a a good idea
-to pass the two inputs through a setpts=PTS-STARTPTS filter to
-have them begin in the same zero timestamp, as it does the example for
-the movie filter.
-
-
Follow some examples:
-
# draw the overlay at 10 pixels from the bottom right
-# corner of the main video.
-overlay=main_w-overlay_w-10:main_h-overlay_h-10
-
-# insert a transparent PNG logo in the bottom left corner of the input
-movie=logo.png [logo];
-[in][logo] overlay=10:main_h-overlay_h-10 [out]
-
-# insert 2 different transparent PNG logos (second logo on bottom
-# right corner):
-movie=logo1.png [logo1];
-movie=logo2.png [logo2];
-[in][logo1] overlay=10:H-h-10 [in+logo1];
-[in+logo1][logo2] overlay=W-w-10:H-h-10 [out]
-
-# add a transparent color layer on top of the main video,
-# WxH specifies the size of the main input to the overlay filter
-color=red.3:WxH [over]; [in][over] overlay [out]
-
-
-
You can chain together more overlays but the efficiency of such
-approach is yet to be tested.
-
Add paddings to the input image, and places the original input at the
-given coordinates x, y.
-
-
It accepts the following parameters:
-width:height:x:y:color.
-
-
The parameters width, height, x, and y are
-expressions containing the following constants:
-
-
-
‘in_w, in_h’
-
the input video width and height
-
-
-
‘iw, ih’
-
same as in_w and in_h
-
-
-
‘out_w, out_h’
-
the output width and height, that is the size of the padded area as
-specified by the width and height expressions
-
-
-
‘ow, oh’
-
same as out_w and out_h
-
-
-
‘x, y’
-
x and y offsets as specified by the x and y
-expressions, or NAN if not yet specified
-
-
-
‘a’
-
same as iw / ih
-
-
-
‘sar’
-
input sample aspect ratio
-
-
-
‘dar’
-
input display aspect ratio, it is the same as (iw / ih) * sar
-
-
-
‘hsub, vsub’
-
horizontal and vertical chroma subsample values. For example for the
-pixel format "yuv422p" hsub is 2 and vsub is 1.
-
-
-
-
Follows the description of the accepted parameters.
-
-
-
‘width, height’
-
-
Specify the size of the output image with the paddings added. If the
-value for width or height is 0, the corresponding input size
-is used for the output.
-
-
The width expression can reference the value set by the
-height expression, and vice versa.
-
-
The default value of width and height is 0.
-
-
-
‘x, y’
-
-
Specify the offsets where to place the input image in the padded area
-with respect to the top/left border of the output image.
-
-
The x expression can reference the value set by the y
-expression, and vice versa.
-
-
The default value of x and y is 0.
-
-
-
‘color’
-
-
Specify the color of the padded area, it can be the name of a color
-(case insensitive match) or a 0xRRGGBB[AA] sequence.
-
-
The default value of color is "black".
-
-
-
-
-
Some examples follow:
-
-
# Add paddings with color "violet" to the input video. Output video
-# size is 640x480, the top-left corner of the input video is placed at
-# column 0, row 40.
-pad=640:480:0:40:violet
-
-# pad the input to get an output with dimensions increased bt 3/2,
-# and put the input video at the center of the padded area
-pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
-
-# pad the input to get a squared output with size equal to the maximum
-# value between the input width and height, and put the input video at
-# the center of the padded area
-pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
-
-# pad the input to get a final w/h ratio of 16:9
-pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
-
-# for anamorphic video, in order to set the output display aspect ratio,
-# it is necessary to use sar in the expression, according to the relation:
-# (ih * X / ih) * sar = output_dar
-# X = output_dar / sar
-pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2"
-
-# double output size and put the input video in the bottom-right
-# corner of the output padded area
-pad="2*iw:2*ih:ow-iw:oh-ih"
-
Scale the input video to width:height[:interl={1|-1}] and/or convert the image format.
-
-
The parameters width and height are expressions containing
-the following constants:
-
-
-
‘in_w, in_h’
-
the input width and height
-
-
-
‘iw, ih’
-
same as in_w and in_h
-
-
-
‘out_w, out_h’
-
the output (cropped) width and height
-
-
-
‘ow, oh’
-
same as out_w and out_h
-
-
-
‘a’
-
same as iw / ih
-
-
-
‘sar’
-
input sample aspect ratio
-
-
-
‘dar’
-
input display aspect ratio, it is the same as (iw / ih) * sar
-
-
-
‘hsub, vsub’
-
horizontal and vertical chroma subsample values. For example for the
-pixel format "yuv422p" hsub is 2 and vsub is 1.
-
-
-
-
If the input image format is different from the format requested by
-the next filter, the scale filter will convert the input to the
-requested format.
-
-
If the value for width or height is 0, the respective input
-size is used for the output.
-
-
If the value for width or height is -1, the scale filter will
-use, for the respective output size, a value that maintains the aspect
-ratio of the input image.
-
-
The default value of width and height is 0.
-
-
Valid values for the optional parameter interl are:
-
-
-
‘1’
-
force interlaced aware scaling
-
-
-
‘-1’
-
select interlaced aware scaling depending on whether the source frames
-are flagged as interlaced or not
-
-
-
-
Some examples follow:
-
# scale the input video to a size of 200x100.
-scale=200:100
-
-# scale the input to 2x
-scale=2*iw:2*ih
-# the above is the same as
-scale=2*in_w:2*in_h
-
-# scale the input to half size
-scale=iw/2:ih/2
-
-# increase the width, and set the height to the same size
-scale=3/2*iw:ow
-
-# seek for Greek harmony
-scale=iw:1/PHI*iw
-scale=ih*PHI:ih
-
-# increase the height, and set the width to 3/2 of the height
-scale=3/2*oh:3/5*ih
-
-# increase the size, but make the size a multiple of the chroma
-scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
-
-# increase the width to a maximum of 500 pixels, keep the same input aspect ratio
-scale='min(500\, iw*3/2):-1'
-
It accepts in input an expression, which is evaluated for each input
-frame. If the expression is evaluated to a non-zero value, the frame
-is selected and passed to the output, otherwise it is discarded.
-
-
The expression can contain the following constants:
-
-
-
‘n’
-
the sequential number of the filtered frame, starting from 0
-
-
-
‘selected_n’
-
the sequential number of the selected frame, starting from 0
-
-
-
‘prev_selected_n’
-
the sequential number of the last selected frame, NAN if undefined
-
-
-
‘TB’
-
timebase of the input timestamps
-
-
-
‘pts’
-
the PTS (Presentation TimeStamp) of the filtered video frame,
-expressed in TB units, NAN if undefined
-
-
-
‘t’
-
the PTS (Presentation TimeStamp) of the filtered video frame,
-expressed in seconds, NAN if undefined
-
-
-
‘prev_pts’
-
the PTS of the previously filtered video frame, NAN if undefined
-
-
-
‘prev_selected_pts’
-
the PTS of the last previously filtered video frame, NAN if undefined
-
-
-
‘prev_selected_t’
-
the PTS of the last previously selected video frame, NAN if undefined
-
-
-
‘start_pts’
-
the PTS of the first video frame in the video, NAN if undefined
-
-
-
‘start_t’
-
the time of the first video frame in the video, NAN if undefined
-
-
-
‘pict_type’
-
the type of the filtered frame, can assume one of the following
-values:
-
-
‘I’
-
‘P’
-
‘B’
-
‘S’
-
‘SI’
-
‘SP’
-
‘BI’
-
-
-
-
‘interlace_type’
-
the frame interlace type, can assume one of the following values:
-
-
‘PROGRESSIVE’
-
the frame is progressive (not interlaced)
-
-
‘TOPFIRST’
-
the frame is top-field-first
-
-
‘BOTTOMFIRST’
-
the frame is bottom-field-first
-
-
-
-
-
‘key’
-
1 if the filtered frame is a key-frame, 0 otherwise
-
-
-
‘pos’
-
the position in the file of the filtered frame, -1 if the information
-is not available (e.g. for synthetic video)
-
-
-
-
The default value of the select expression is "1".
-
-
Some examples follow:
-
-
# select all frames in input
-select
-
-# the above is the same as:
-select=1
-
-# skip all frames:
-select=0
-
-# select only I-frames
-select='eq(pict_type\,I)'
-
-# select one frame every 100
-select='not(mod(n\,100))'
-
-# select only frames contained in the 10-20 time interval
-select='gte(t\,10)*lte(t\,20)'
-
-# select only I frames contained in the 10-20 time interval
-select='gte(t\,10)*lte(t\,20)*eq(pict_type\,I)'
-
-# select frames with a minimum distance of 10 seconds
-select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
-
Set the Display Aspect Ratio for the filter output video.
-
-
This is done by changing the specified Sample (aka Pixel) Aspect
-Ratio, according to the following equation:
-DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR
-
-
Keep in mind that this filter does not modify the pixel dimensions of
-the video frame. Also the display aspect ratio set by this filter may
-be changed by later filters in the filterchain, e.g. in case of
-scaling or if another "setdar" or a "setsar" filter is applied.
-
-
The filter accepts a parameter string which represents the wanted
-display aspect ratio.
-The parameter can be a floating point number string, or an expression
-of the form num:den, where num and den are the
-numerator and denominator of the aspect ratio.
-If the parameter is not specified, it is assumed the value "0:1".
-
-
For example to change the display aspect ratio to 16:9, specify:
-
setdar=16:9
-# the above is equivalent to
-setdar=1.77777
-
Set the Sample (aka Pixel) Aspect Ratio for the filter output video.
-
-
Note that as a consequence of the application of this filter, the
-output display aspect ratio will change according to the following
-equation:
-DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR
-
-
Keep in mind that the sample aspect ratio set by this filter may be
-changed by later filters in the filterchain, e.g. if another "setsar"
-or a "setdar" filter is applied.
-
-
The filter accepts a parameter string which represents the wanted
-sample aspect ratio.
-The parameter can be a floating point number string, or an expression
-of the form num:den, where num and den are the
-numerator and denominator of the aspect ratio.
-If the parameter is not specified, it is assumed the value "0:1".
-
-
For example to change the sample aspect ratio to 10:11, specify:
-
Set the timebase to use for the output frames timestamps.
-It is mainly useful for testing timebase configuration.
-
-
It accepts in input an arithmetic expression representing a rational.
-The expression can contain the constants "AVTB" (the
-default timebase), and "intb" (the input timebase).
-
-
The default value for the input is "intb".
-
-
Follow some examples.
-
-
# set the timebase to 1/25
-settb=1/25
-
-# set the timebase to 1/10
-settb=0.1
-
-#set the timebase to 1001/1000
-settb=1+0.001
-
-#set the timebase to 2*intb
-settb=2*intb
-
-#set the default timebase value
-settb=AVTB
-
Show a line containing various information for each input video frame.
-The input video is not modified.
-
-
The shown line contains a sequence of key/value pairs of the form
-key:value.
-
-
A description of each shown parameter follows:
-
-
-
‘n’
-
sequential number of the input frame, starting from 0
-
-
-
‘pts’
-
Presentation TimeStamp of the input frame, expressed as a number of
-time base units. The time base unit depends on the filter input pad.
-
-
-
‘pts_time’
-
Presentation TimeStamp of the input frame, expressed as a number of
-seconds
-
-
-
‘pos’
-
position of the frame in the input stream, -1 if this information in
-unavailable and/or meaningless (for example in case of synthetic video)
-
-
-
‘fmt’
-
pixel format name
-
-
-
‘sar’
-
sample aspect ratio of the input frame, expressed in the form
-num/den
-
-
-
‘s’
-
size of the input frame, expressed in the form
-widthxheight
-
-
-
‘i’
-
interlaced mode ("P" for "progressive", "T" for top field first, "B"
-for bottom field first)
-
-
-
‘iskey’
-
1 if the frame is a key frame, 0 otherwise
-
-
-
‘type’
-
picture type of the input frame ("I" for an I-frame, "P" for a
-P-frame, "B" for a B-frame, "?" for unknown type).
-Check also the documentation of the AVPictureType enum and of
-the av_get_picture_type_char function defined in
-‘libavutil/avutil.h’.
-
-
-
‘checksum’
-
Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame
-
-
-
‘plane_checksum’
-
Adler-32 checksum (printed in hexadecimal) of each plane of the input frame,
-expressed in the form "[c0c1c2c3]"
-
Select the most representative frame in a given sequence of consecutive frames.
-
-
It accepts as argument the frames batch size to analyze (default N=100);
-in a set of N frames, the filter will pick one of them, and then handle
-the next batch of N frames until the end.
-
-
Since the filter keeps track of the whole frames sequence, a bigger N
-value will result in a higher memory usage, so a high value is not recommended.
-
-
The following example extract one picture each 50 frames:
-
thumbnail=50
-
-
-
Complete example of a thumbnail creation with ffmpeg:
-
It accepts the following parameters:
-luma_msize_x:luma_msize_y:luma_amount:chroma_msize_x:chroma_msize_y:chroma_amount
-
-
Negative values for the amount will blur the input video, while positive
-values will sharpen. All parameters are optional and default to the
-equivalent of the string ’5:5:1.0:5:5:0.0’.
-
-
-
‘luma_msize_x’
-
Set the luma matrix horizontal size. It can be an integer between 3
-and 13, default value is 5.
-
-
-
‘luma_msize_y’
-
Set the luma matrix vertical size. It can be an integer between 3
-and 13, default value is 5.
-
-
-
‘luma_amount’
-
Set the luma effect strength. It can be a float number between -2.0
-and 5.0, default value is 1.0.
-
-
-
‘chroma_msize_x’
-
Set the chroma matrix horizontal size. It can be an integer between 3
-and 13, default value is 5.
-
-
-
‘chroma_msize_y’
-
Set the chroma matrix vertical size. It can be an integer between 3
-and 13, default value is 5.
-
-
-
‘chroma_amount’
-
Set the chroma effect strength. It can be a float number between -2.0
-and 5.0, default value is 0.0.
-
-
-
-
-
# Strong luma sharpen effect parameters
-unsharp=7:7:2.5
-
-# Strong blur of both luma and chroma parameters
-unsharp=7:7:-2:7:7:-2
-
-# Use the default values with ffmpeg
-ffmpeg -i in.avi -vf "unsharp" out.mp4
-
Buffer video frames, and make them available to the filter chain.
-
-
This source is mainly intended for a programmatic use, in particular
-through the interface defined in ‘libavfilter/vsrc_buffer.h’.
-
-
It accepts the following parameters:
-width:height:pix_fmt_string:timebase_num:timebase_den:sample_aspect_ratio_num:sample_aspect_ratio.den:scale_params
-
-
All the parameters but scale_params need to be explicitly
-defined.
-
-
Follows the list of the accepted parameters.
-
-
-
‘width, height’
-
Specify the width and height of the buffered video frames.
-
-
-
‘pix_fmt_string’
-
A string representing the pixel format of the buffered video frames.
-It may be a number corresponding to a pixel format, or a pixel format
-name.
-
-
-
‘timebase_num, timebase_den’
-
Specify numerator and denomitor of the timebase assumed by the
-timestamps of the buffered frames.
-
Specify numerator and denominator of the sample aspect ratio assumed
-by the video frames.
-
-
-
‘scale_params’
-
Specify the optional parameters to be used for the scale filter which
-is automatically inserted when an input change is detected in the
-input size or format.
-
will instruct the source to accept video frames with size 320x240 and
-with format "yuv410p", assuming 1/24 as the timestamps timebase and
-square pixels (1:1 sample aspect ratio).
-Since the pixel format with name "yuv410p" corresponds to the number 6
-(check the enum PixelFormat definition in ‘libavutil/pixfmt.h’),
-this example corresponds to:
-
Create a pattern generated by an elementary cellular automaton.
-
-
The initial state of the cellular automaton can be defined through the
-‘filename’, and ‘pattern’ options. If such options are
-not specified an initial state is created randomly.
-
-
At each new frame a new row in the video is filled with the result of
-the cellular automaton next generation. The behavior when the whole
-frame is filled is defined by the ‘scroll’ option.
-
-
This source accepts a list of options in the form of
-key=value pairs separated by ":". A description of the
-accepted options follows.
-
-
-
‘filename, f’
-
Read the initial cellular automaton state, i.e. the starting row, from
-the specified file.
-In the file, each non-whitespace character is considered an alive
-cell, a newline will terminate the row, and further characters in the
-file will be ignored.
-
-
-
‘pattern, p’
-
Read the initial cellular automaton state, i.e. the starting row, from
-the specified string.
-
-
Each non-whitespace character in the string is considered an alive
-cell, a newline will terminate the row, and further characters in the
-string will be ignored.
-
-
-
‘rate, r’
-
Set the video rate, that is the number of frames generated per second.
-Default is 25.
-
-
-
‘random_fill_ratio, ratio’
-
Set the random fill ratio for the initial cellular automaton row. It
-is a floating point number value ranging from 0 to 1, defaults to
-1/PHI.
-
-
This option is ignored when a file or a pattern is specified.
-
-
-
‘random_seed, seed’
-
Set the seed for filling randomly the initial row, must be an integer
-included between 0 and UINT32_MAX. If not specified, or if explicitly
-set to -1, the filter will try to use a good random seed on a best
-effort basis.
-
-
-
‘rule’
-
Set the cellular automaton rule, it is a number ranging from 0 to 255.
-Default value is 110.
-
-
-
‘size, s’
-
Set the size of the output video.
-
-
If ‘filename’ or ‘pattern’ is specified, the size is set
-by default to the width of the specified initial state row, and the
-height is set to width * PHI.
-
-
If ‘size’ is set, it must contain the width of the specified
-pattern string, and the specified pattern will be centered in the
-larger row.
-
-
If a filename or a pattern string is not specified, the size value
-defaults to "320x518" (used for a randomly generated initial state).
-
-
-
‘scroll’
-
If set to 1, scroll the output upward when all the rows in the output
-have been already filled. If set to 0, the new generated row will be
-written over the top row just after the bottom row is filled.
-Defaults to 1.
-
-
-
‘start_full, full’
-
If set to 1, completely fill the output with generated rows before
-outputting the first frame.
-This is the default behavior, for disabling set the value to 0.
-
-
-
‘stitch’
-
If set to 1, stitch the left and right row edges together.
-This is the default behavior, for disabling set the value to 0.
-
It accepts the following parameters:
-color:frame_size:frame_rate
-
-
Follows the description of the accepted parameters.
-
-
-
‘color’
-
Specify the color of the source. It can be the name of a color (case
-insensitive match) or a 0xRRGGBB[AA] sequence, possibly followed by an
-alpha specifier. The default value is "black".
-
-
-
‘frame_size’
-
Specify the size of the sourced video, it may be a string of the form
-widthxheight, or the name of a size abbreviation. The
-default value is "320x240".
-
-
-
‘frame_rate’
-
Specify the frame rate of the sourced video, as the number of frames
-generated per second. It has to be a string in the format
-frame_rate_num/frame_rate_den, an integer number, a float
-number or a valid video frame rate abbreviation. The default value is
-"25".
-
-
-
-
-
For example the following graph description will generate a red source
-with an opacity of 0.2, with size "qcif" and a frame rate of 10
-frames per second, which will be overlayed over the source connected
-to the pad with identifier "in".
-
It accepts the syntax: movie_name[:options] where
-movie_name is the name of the resource to read (not necessarily
-a file but also a device or a stream accessed through some protocol),
-and options is an optional sequence of key=value
-pairs, separated by ":".
-
-
The description of the accepted options follows.
-
-
-
‘format_name, f’
-
Specifies the format assumed for the movie to read, and can be either
-the name of a container or an input device. If not specified the
-format is guessed from movie_name or by probing.
-
-
-
‘seek_point, sp’
-
Specifies the seek point in seconds, the frames will be output
-starting from this seek point, the parameter is evaluated with
-av_strtod so the numerical value may be suffixed by an IS
-postfix. Default value is "0".
-
-
-
‘stream_index, si’
-
Specifies the index of the video stream to read. If the value is -1,
-the best suited video stream will be automatically selected. Default
-value is "-1".
-
-
-
-
-
This filter allows to overlay a second video on top of main input of
-a filtergraph as shown in this graph:
-
# skip 3.2 seconds from the start of the avi file in.avi, and overlay it
-# on top of the input labelled as "in".
-movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [movie];
-[in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
-
-# read from a video4linux2 device, and overlay it on top of the input
-# labelled as "in"
-movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [movie];
-[in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
-
-
Generate various test patterns, as generated by the MPlayer test filter.
-
-
The size of the generated video is fixed, and is 256x256.
-This source is useful in particular for testing encoding features.
-
-
This source accepts an optional sequence of key=value pairs,
-separated by ":". The description of the accepted options follows.
-
-
-
‘rate, r’
-
Specify the frame rate of the sourced video, as the number of frames
-generated per second. It has to be a string in the format
-frame_rate_num/frame_rate_den, an integer number, a float
-number or a valid video frame rate abbreviation. The default value is
-"25".
-
-
-
‘duration, d’
-
Set the video duration of the sourced video. The accepted syntax is:
-
[-]HH[:MM[:SS[.m...]]]
-[-]S+[.m...]
-
-
See also the function av_parse_time().
-
-
If not specified, or the expressed duration is negative, the video is
-supposed to be generated forever.
-
-
-
‘test, t’
-
-
Set the number or the name of the test to perform. Supported tests are:
-
-
‘dc_luma’
-
‘dc_chroma’
-
‘freq_luma’
-
‘freq_chroma’
-
‘amp_luma’
-
‘amp_chroma’
-
‘cbp’
-
‘mv’
-
‘ring1’
-
‘ring2’
-
‘all’
-
-
-
Default value is "all", which will cycle through the list of all tests.
-
size is the size of the video to generate, may be a string of the
-form widthxheight or a frame size abbreviation.
-rate is the rate of the video to generate, may be a string of
-the form num/den or a frame rate abbreviation.
-src_name is the name to the frei0r source to load. For more
-information regarding frei0r and how to set the parameters read the
-section frei0r in the description of the video filters.
+
# generate a frei0r partik0l source with size 200x200 and frame rate 10
-# which is overlayed on the overlay filter main input
-frei0r_src=200x200:10:partik0l=1234 [overlay]; [in][overlay] overlay
-
This source is based on a generalization of John Conway’s life game.
+
For details about the authorship, see the Git history of the project
+(git://source.ffmpeg.org/ffmpeg), e.g. by typing the command
+git log in the FFmpeg source directory, or browsing the
+online repository at http://source.ffmpeg.org.
-
The sourced input represents a life grid, each pixel represents a cell
-which can be in one of two possible states, alive or dead. Every cell
-interacts with its eight neighbours, which are the cells that are
-horizontally, vertically, or diagonally adjacent.
-
-
At each interaction the grid evolves according to the adopted rule,
-which specifies the number of neighbor alive cells which will make a
-cell stay alive or born. The ‘rule’ option allows to specify
-the rule to adopt.
-
-
This source accepts a list of options in the form of
-key=value pairs separated by ":". A description of the
-accepted options follows.
-
-
-
‘filename, f’
-
Set the file from which to read the initial grid state. In the file,
-each non-whitespace character is considered an alive cell, and newline
-is used to delimit the end of each row.
-
-
If this option is not specified, the initial grid is generated
-randomly.
-
-
-
‘rate, r’
-
Set the video rate, that is the number of frames generated per second.
-Default is 25.
-
-
-
‘random_fill_ratio, ratio’
-
Set the random fill ratio for the initial random grid. It is a
-floating point number value ranging from 0 to 1, defaults to 1/PHI.
-It is ignored when a file is specified.
-
-
-
‘random_seed, seed’
-
Set the seed for filling the initial random grid, must be an integer
-included between 0 and UINT32_MAX. If not specified, or if explicitly
-set to -1, the filter will try to use a good random seed on a best
-effort basis.
-
-
-
‘rule’
-
Set the life rule.
-
-
A rule can be specified with a code of the kind "SNS/BNB",
-where NS and NB are sequences of numbers in the range 0-8,
-NS specifies the number of alive neighbor cells which make a
-live cell stay alive, and NB the number of alive neighbor cells
-which make a dead cell to become alive (i.e. to "born").
-"s" and "b" can be used in place of "S" and "B", respectively.
-
-
Alternatively a rule can be specified by an 18-bits integer. The 9
-high order bits are used to encode the next cell state if it is alive
-for each number of neighbor alive cells, the low order bits specify
-the rule for "borning" new cells. Higher order bits encode for an
-higher number of neighbor cells.
-For example the number 6153 = (12<<9)+9 specifies a stay alive
-rule of 12 and a born rule of 9, which corresponds to "S23/B03".
-
-
Default value is "S23/B3", which is the original Conway’s game of life
-rule, and will keep a cell alive if it has 2 or 3 neighbor alive
-cells, and will born a new cell if there are three alive cells around
-a dead cell.
-
-
-
‘size, s’
-
Set the size of the output video.
-
-
If ‘filename’ is specified, the size is set by default to the
-same size of the input file. If ‘size’ is set, it must contain
-the size specified in the input file, and the initial grid defined in
-that file is centered in the larger resulting area.
-
-
If a filename is not specified, the size value defaults to "320x240"
-(used for a randomly generated initial grid).
-
-
-
‘stitch’
-
If set to 1, stitch the left and right grid edges together, and the
-top and bottom edges also. Defaults to 1.
-
-
-
‘mold’
-
Set cell mold speed. If set, a dead cell will go from ‘death_color’ to
-‘mold_color’ with a step of ‘mold’. ‘mold’ can have a
-value from 0 to 255.
-
-
-
‘life_color’
-
Set the color of living (or new born) cells.
-
-
-
‘death_color’
-
Set the color of dead cells. If ‘mold’ is set, this is the first color
-used to represent a dead cell.
-
-
-
‘mold_color’
-
Set mold color, for definitely dead and moldy cells.
-
The nullsrc source returns unprocessed video frames. It is
-mainly useful to be employed in analysis / debugging tools, or as the
-source for filters which ignore the input data.
-
-
The rgbtestsrc source generates an RGB test pattern useful for
-detecting RGB vs BGR issues. You should see a red, green and blue
-stripe from top to bottom.
-
-
The testsrc source generates a test video pattern, showing a
-color pattern, a scrolling gradient and a timestamp. This is mainly
-intended for testing purposes.
-
-
These sources accept an optional sequence of key=value pairs,
-separated by ":". The description of the accepted options follows.
-
-
-
‘size, s’
-
Specify the size of the sourced video, it may be a string of the form
-widthxheight, or the name of a size abbreviation. The
-default value is "320x240".
-
-
-
‘rate, r’
-
Specify the frame rate of the sourced video, as the number of frames
-generated per second. It has to be a string in the format
-frame_rate_num/frame_rate_den, an integer number, a float
-number or a valid video frame rate abbreviation. The default value is
-"25".
-
-
-
‘sar’
-
Set the sample aspect ratio of the sourced video.
-
-
-
‘duration, d’
-
Set the video duration of the sourced video. The accepted syntax is:
-
[-]HH[:MM[:SS[.m...]]]
-[-]S+[.m...]
-
-
See also the function av_parse_time().
-
-
If not specified, or the expressed duration is negative, the video is
-supposed to be generated forever.
-
-
-
‘decimals, n’
-
Set the number of decimals to show in the timestamp, only used in the
-testsrc source.
-
-
The displayed timestamp value will correspond to the original
-timestamp value multiplied by the power of 10 of the specified
-value. Default value is 0.
-
-
-
-
For example the following:
-
testsrc=duration=5.3:size=qcif:rate=10
-
-
-
will generate a video with a duration of 5.3 seconds, with size
-176x144 and a frame rate of 10 frames per second.
-
-
If the input content is to be ignored, nullsrc can be used. The
-following command generates noise in the luminance plane by employing
-the mp=geq filter:
-
Buffer video frames, and make them available to the end of the filter
-graph.
-
-
This sink is mainly intended for a programmatic use, in particular
-through the interface defined in ‘libavfilter/buffersink.h’.
-
-
It does not require a string parameter in input, but you need to
-specify a pointer to a list of supported pixel formats terminated by
--1 in the opaque parameter provided to avfilter_init_filter
-when initializing this sink.
-
FFmpeg is able to dump metadata from media files into a simple UTF-8-encoded
-INI-like text file and then load it back using the metadata muxer/demuxer.
-
-
The file format is as follows:
-
-
-A file consists of a header and a number of metadata tags divided into sections,
-each on its own line.
-
-
-The header is a ’;FFMETADATA’ string, followed by a version number (now 1).
-
-
-Metadata tags are of the form ’key=value’
-
-
-Immediately after header follows global metadata
-
-
-After global metadata there may be sections with per-stream/per-chapter
-metadata.
-
-
-A section starts with the section name in uppercase (i.e. STREAM or CHAPTER) in
-brackets (’[’, ’]’) and ends with next section or end of file.
-
-
-At the beginning of a chapter section there may be an optional timebase to be
-used for start/end values. It must be in form ’TIMEBASE=num/den’, where num and
-den are integers. If the timebase is missing then start/end times are assumed to
-be in milliseconds.
-Next a chapter section must contain chapter start and end times in form
-’START=num’, ’END=num’, where num is a positive integer.
-
-
-Empty lines and lines starting with ’;’ or ’#’ are ignored.
-
-
-Metadata keys or values containing special characters (’=’, ’;’, ’#’, ’\’ and a
-newline) must be escaped with a backslash ’\’.
-
-
-Note that whitespace in metadata (e.g. foo = bar) is considered to be a part of
-the tag (in the example above key is ’foo ’, value is ’ bar’).
-
-
-
A ffmetadata file might look like this:
-
;FFMETADATA1
-title=bike\\shed
-;this is a comment
-artist=FFmpeg troll team
-
-[CHAPTER]
-TIMEBASE=1/1000
-START=0
-#chapter ends at 0:01:00
-END=60000
-title=chapter \#1
-[STREAM]
-title=multi\
-line
-
FFplay is a very simple and portable media player using the FFmpeg
+libraries and the SDL library. It is mostly used as a testbed for the
+various FFmpeg APIs.
+
All the numerical options, if not specified otherwise, accept a string
+representing a number as input, which may be followed by one of the SI
+unit prefixes, for example: ’K’, ’M’, or ’G’.
+
+
If ’i’ is appended to the SI unit prefix, the complete prefix will be
+interpreted as a unit prefix for binary multiplies, which are based on
+powers of 1024 instead of powers of 1000. Appending ’B’ to the SI unit
+prefix multiplies the value by 8. This allows using, for example:
+’KB’, ’MiB’, ’G’ and ’B’ as number suffixes.
+
+
Options which do not take arguments are boolean options, and set the
+corresponding value to true. They can be set to false by prefixing
+the option name with "no". For example using "-nofoo"
+will set the boolean option with name "foo" to false.
+
Some options are applied per-stream, e.g. bitrate or codec. Stream specifiers
+are used to precisely specify which stream(s) a given option belongs to.
+
+
A stream specifier is a string generally appended to the option name and
+separated from it by a colon. E.g. -codec:a:1 ac3 contains the
+a:1 stream specifier, which matches the second audio stream. Therefore, it
+would select the ac3 codec for the second audio stream.
+
+
A stream specifier can match several streams, so that the option is applied to all
+of them. E.g. the stream specifier in -b:a 128k matches all audio
+streams.
+
+
An empty stream specifier matches all streams. For example, -codec copy
+or -codec: copy would copy all the streams without reencoding.
+
+
Possible forms of stream specifiers are:
+
+
‘stream_index’
+
Matches the stream with this index. E.g. -threads:1 4 would set the
+thread count for the second stream to 4.
+
+
‘stream_type[:stream_index]’
+
stream_type is one of following: ’v’ for video, ’a’ for audio, ’s’ for subtitle,
+’d’ for data, and ’t’ for attachments. If stream_index is given, then it matches
+stream number stream_index of this type. Otherwise, it matches all
+streams of this type.
+
+
‘p:program_id[:stream_index]’
+
If stream_index is given, then it matches the stream with number stream_index
+in the program with the id program_id. Otherwise, it matches all streams in the
+program.
+
Show help. An optional parameter may be specified to print help about a specific
+item. If no argument is specified, only basic (non advanced) tool
+options are shown.
+
+
Possible values of arg are:
+
+
‘long’
+
Print advanced tool options in addition to the basic tool options.
+
+
+
‘full’
+
Print complete list of options, including shared and private options
+for encoders, decoders, demuxers, muxers, filters, etc.
+
+
+
‘decoder=decoder_name’
+
Print detailed information about the decoder named decoder_name. Use the
+‘-decoders’ option to get a list of all decoders.
+
+
+
‘encoder=encoder_name’
+
Print detailed information about the encoder named encoder_name. Use the
+‘-encoders’ option to get a list of all encoders.
+
+
+
‘demuxer=demuxer_name’
+
Print detailed information about the demuxer named demuxer_name. Use the
+‘-formats’ option to get a list of all demuxers and muxers.
+
+
+
‘muxer=muxer_name’
+
Print detailed information about the muxer named muxer_name. Use the
+‘-formats’ option to get a list of all muxers and demuxers.
+
+
+
‘filter=filter_name’
+
Print detailed information about the filter name filter_name. Use the
+‘-filters’ option to get a list of all filters.
+
+
+
+
+
‘-version’
+
Show version.
+
+
+
‘-formats’
+
Show available formats.
+
+
+
‘-codecs’
+
Show all codecs known to libavcodec.
+
+
Note that the term ’codec’ is used throughout this documentation as a shortcut
+for what is more correctly called a media bitstream format.
+
+
+
‘-decoders’
+
Show available decoders.
+
+
+
‘-encoders’
+
Show all available encoders.
+
+
+
‘-bsfs’
+
Show available bitstream filters.
+
+
+
‘-protocols’
+
Show available protocols.
+
+
+
‘-filters’
+
Show available libavfilter filters.
+
+
+
‘-pix_fmts’
+
Show available pixel formats.
+
+
+
‘-sample_fmts’
+
Show available sample formats.
+
+
+
‘-layouts’
+
Show channel names and standard channel layouts.
+
Set the logging level used by the library.
+Adding "repeat+" indicates that repeated log output should not be compressed
+to the first line and the "Last message repeated n times" line will be
+omitted. "repeat" can also be used alone.
+If "repeat" is used alone, and with no prior loglevel set, the default
+loglevel will be used. If multiple loglevel parameters are given, using
+’repeat’ will not change the loglevel.
+loglevel is a number or a string containing one of the following values:
+
+
‘quiet’
+
Show nothing at all; be silent.
+
+
‘panic’
+
Only show fatal errors which could lead the process to crash, such as
+and assert failure. This is not currently used for anything.
+
+
‘fatal’
+
Only show fatal errors. These are errors after which the process absolutely
+cannot continue after.
+
+
‘error’
+
Show all errors, including ones which can be recovered from.
+
+
‘warning’
+
Show all warnings and errors. Any message related to possibly
+incorrect or unexpected events will be shown.
+
+
‘info’
+
Show informative messages during processing. This is in addition to
+warnings and errors. This is the default value.
+
+
‘verbose’
+
Same as info, except more verbose.
+
+
‘debug’
+
Show everything, including debugging information.
+
+
+
+
By default the program logs to stderr, if coloring is supported by the
+terminal, colors are used to mark errors and warnings. Log coloring
+can be disabled setting the environment variable
+AV_LOG_FORCE_NOCOLOR or NO_COLOR, or can be forced setting
+the environment variable AV_LOG_FORCE_COLOR.
+The use of the environment variable NO_COLOR is deprecated and
+will be dropped in a following FFmpeg version.
+
+
+
‘-report’
+
Dump full command line and console output to a file named
+program-YYYYMMDD-HHMMSS.log in the current
+directory.
+This file can be useful for bug reports.
+It also implies -loglevel verbose.
+
+
Setting the environment variable FFREPORT to any value has the
+same effect. If the value is a ’:’-separated key=value sequence, these
+options will affect the report; options values must be escaped if they
+contain special characters or the options delimiter ’:’ (see the
+“Quoting and escaping” section in the ffmpeg-utils manual). The
+following option is recognized:
+
+
‘file’
+
set the file name to use for the report; %p is expanded to the name
+of the program, %t is expanded to a timestamp, %% is expanded
+to a plain %
+
+
+
+
Errors in parsing the environment variable are not fatal, and will not
+appear in the report.
+
+
+
‘-cpuflags flags (global)’
+
Allows setting and clearing cpu flags. This option is intended
+for testing. Do not use it unless you know what you’re doing.
+
Set OpenCL environment options. This option is only available when
+FFmpeg has been compiled with --enable-opencl.
+
+
options must be a list of key=value option pairs
+separated by ’:’. See the “OpenCL Options” section in the
+ffmpeg-utils manual for the list of supported options.
+
These options are provided directly by the libavformat, libavdevice and
+libavcodec libraries. To see the list of available AVOptions, use the
+‘-help’ option. They are separated into two categories:
+
+
‘generic’
+
These options can be set for any container, codec or device. Generic options
+are listed under AVFormatContext options for containers/devices and under
+AVCodecContext options for codecs.
+
+
‘private’
+
These options are specific to the given container, device or codec. Private
+options are listed under their corresponding containers/devices/codecs.
+
+
+
+
For example to write an ID3v2.3 header instead of a default ID3v2.4 to
+an MP3 file, use the ‘id3v2_version’ private option of the MP3
+muxer:
+
ffmpeg -i input.flac -id3v2_version 3 out.mp3
+
+
+
All codec AVOptions are per-stream, and thus a stream specifier
+should be attached to them.
+
+
Note: the ‘-nooption’ syntax cannot be used for boolean
+AVOptions, use ‘-option 0’/‘-option 1’.
+
+
Note: the old undocumented way of specifying per-stream AVOptions by
+prepending v/a/s to the options name is now obsolete and will be
+removed soon.
+
Set frame size (WxH or abbreviation), needed for videos which do
+not contain a header with the frame size like raw YUV. This option
+has been deprecated in favor of private options, try -video_size.
+
+
‘-an’
+
Disable audio.
+
+
‘-vn’
+
Disable video.
+
+
‘-ss pos’
+
Seek to a given position in seconds.
+
+
‘-t duration’
+
play <duration> seconds of audio/video
+
+
‘-bytes’
+
Seek by bytes.
+
+
‘-nodisp’
+
Disable graphical display.
+
+
‘-f fmt’
+
Force format.
+
+
‘-window_title title’
+
Set window title (default is the input filename).
+
+
‘-loop number’
+
Loops movie playback <number> times. 0 means forever.
+
+
‘-showmode mode’
+
Set the show mode to use.
+Available values for mode are:
+
+
‘0, video’
+
show video
+
+
‘1, waves’
+
show audio waves
+
+
‘2, rdft’
+
show audio frequency band using RDFT ((Inverse) Real Discrete Fourier Transform)
+
+
+
+
Default value is "video", if video is not present or cannot be played
+"rdft" is automatically selected.
+
+
You can interactively cycle through the available show modes by
+pressing the key <w>.
+
+
+
‘-vf filtergraph’
+
Create the filtergraph specified by filtergraph and use it to
+filter the video stream.
+
+
filtergraph is a description of the filtergraph to apply to
+the stream, and must have a single video input and a single video
+output. In the filtergraph, the input is associated to the label
+in, and the output to the label out. See the
+ffmpeg-filters manual for more information about the filtergraph
+syntax.
+
+
+
‘-af filtergraph’
+
filtergraph is a description of the filtergraph to apply to
+the input audio.
+Use the option "-filters" to show all the available filters (including
+sources and sinks).
+
Set pixel format.
+This option has been deprecated in favor of private options, try -pixel_format.
+
+
+
‘-stats’
+
Print several playback statistics, in particular show the stream
+duration, the codec parameters, the current position in the stream and
+the audio/video synchronisation drift. It is on by default, to
+explicitly disable it you need to specify -nostats.
+
+
+
‘-bug’
+
Work around bugs.
+
+
‘-fast’
+
Non-spec-compliant optimizations.
+
+
‘-genpts’
+
Generate pts.
+
+
‘-rtp_tcp’
+
Force RTP/TCP protocol usage instead of RTP/UDP. It is only meaningful
+if you are streaming with the RTSP protocol.
+
+
‘-sync type’
+
Set the master clock to audio (type=audio), video
+(type=video) or external (type=ext). Default is audio. The
+master clock is used to control audio-video synchronization. Most media
+players use audio as master clock, but in some cases (streaming or high
+quality broadcast) it is necessary to change that. This option is mainly
+used for debugging purposes.
+
+
‘-threads count’
+
Set the thread count.
+
+
‘-ast audio_stream_number’
+
Select the desired audio stream number, counting from 0. The number
+refers to the list of all the input audio streams. If it is greater
+than the number of audio streams minus one, then the last one is
+selected, if it is negative the audio playback is disabled.
+
+
‘-vst video_stream_number’
+
Select the desired video stream number, counting from 0. The number
+refers to the list of all the input video streams. If it is greater
+than the number of video streams minus one, then the last one is
+selected, if it is negative the video playback is disabled.
+
+
‘-sst subtitle_stream_number’
+
Select the desired subtitle stream number, counting from 0. The number
+refers to the list of all the input subtitle streams. If it is greater
+than the number of subtitle streams minus one, then the last one is
+selected, if it is negative the subtitle rendering is disabled.
+
+
‘-autoexit’
+
Exit when video is done playing.
+
+
‘-exitonkeydown’
+
Exit if any key is pressed.
+
+
‘-exitonmousedown’
+
Exit if any mouse button is pressed.
+
+
+
‘-codec:media_specifiercodec_name’
+
Force a specific decoder implementation for the stream identified by
+media_specifier, which can assume the values a (audio),
+v (video), and s subtitle.
+
FFmpeg adopts the following quoting and escaping mechanism, unless
+explicitly specified. The following rules are applied:
+
+
+
+' and \ are special characters (respectively used for
+quoting and escaping). In addition to them, there might be other
+special characters depending on the specific syntax where the escaping
+and quoting are employed.
+
+
+A special character is escaped by prefixing it with a ’\’.
+
+
+All characters enclosed between ” are included literally in the
+parsed string. The quote character ' itself cannot be quoted,
+so you may need to close the quote and escape it.
+
+
+Leading and trailing whitespaces, unless escaped or quoted, are
+removed from the parsed string.
+
+
+
Note that you may need to add a second level of escaping when using
+the command line or a script, which depends on the syntax of the
+adopted shell language.
+
+
The function av_get_token defined in
+‘libavutil/avstring.h’ can be used to parse a token quoted or
+escaped according to the rules defined above.
+
+
The tool ‘tools/ffescape’ in the FFmpeg source tree can be used
+to automatically quote or escape a string in a script.
+
If the value is "now" it takes the current time.
+
+
Time is local time unless Z is appended, in which case it is
+interpreted as UTC.
+If the year-month-day part is not specified it takes the current
+year-month-day.
+
There are two accepted syntaxes for expressing time duration.
+
+
[-][HH:]MM:SS[.m...]
+
+
+
HH expresses the number of hours, MM the number of minutes
+for a maximum of 2 digits, and SS the number of seconds for a
+maximum of 2 digits. The m at the end expresses decimal value for
+SS.
+
+
or
+
+
[-]S+[.m...]
+
+
+
S expresses the number of seconds, with the optional decimal part
+m.
+
+
In both expressions, the optional ‘-’ indicates negative duration.
+
Specify the frame rate of a video, expressed as the number of frames
+generated per second. It has to be a string in the format
+frame_rate_num/frame_rate_den, an integer number, a float
+number or a valid video frame rate abbreviation.
+
A ratio can be expressed as an expression, or in the form
+numerator:denominator.
+
+
Note that a ratio with infinite (1/0) or negative value is
+considered valid, so you should check on the returned value if you
+want to exclude those values.
+
+
The undefined value can be expressed using the "0:0" string.
+
It can be the name of a color as defined below (case insensitive match) or a
+[0x|#]RRGGBB[AA] sequence, possibly followed by @ and a string
+representing the alpha component.
+
+
The alpha component may be a string composed by "0x" followed by an
+hexadecimal number or a decimal number between 0.0 and 1.0, which
+represents the opacity value (‘0x00’ or ‘0.0’ means completely
+transparent, ‘0xff’ or ‘1.0’ completely opaque). If the alpha
+component is not specified then ‘0xff’ is assumed.
+
+
The string ‘random’ will result in a random color.
+
A channel layout specifies the spatial disposition of the channels in
+a multi-channel audio stream. To specify a channel layout, FFmpeg
+makes use of a special syntax.
+
+
Individual channels are identified by an id, as given by the table
+below:
+
+
‘FL’
+
front left
+
+
‘FR’
+
front right
+
+
‘FC’
+
front center
+
+
‘LFE’
+
low frequency
+
+
‘BL’
+
back left
+
+
‘BR’
+
back right
+
+
‘FLC’
+
front left-of-center
+
+
‘FRC’
+
front right-of-center
+
+
‘BC’
+
back center
+
+
‘SL’
+
side left
+
+
‘SR’
+
side right
+
+
‘TC’
+
top center
+
+
‘TFL’
+
top front left
+
+
‘TFC’
+
top front center
+
+
‘TFR’
+
top front right
+
+
‘TBL’
+
top back left
+
+
‘TBC’
+
top back center
+
+
‘TBR’
+
top back right
+
+
‘DL’
+
downmix left
+
+
‘DR’
+
downmix right
+
+
‘WL’
+
wide left
+
+
‘WR’
+
wide right
+
+
‘SDL’
+
surround direct left
+
+
‘SDR’
+
surround direct right
+
+
‘LFE2’
+
low frequency 2
+
+
+
+
Standard channel layout compositions can be specified by using the
+following identifiers:
+
+
‘mono’
+
FC
+
+
‘stereo’
+
FL+FR
+
+
‘2.1’
+
FL+FR+LFE
+
+
‘3.0’
+
FL+FR+FC
+
+
‘3.0(back)’
+
FL+FR+BC
+
+
‘4.0’
+
FL+FR+FC+BC
+
+
‘quad’
+
FL+FR+BL+BR
+
+
‘quad(side)’
+
FL+FR+SL+SR
+
+
‘3.1’
+
FL+FR+FC+LFE
+
+
‘5.0’
+
FL+FR+FC+BL+BR
+
+
‘5.0(side)’
+
FL+FR+FC+SL+SR
+
+
‘4.1’
+
FL+FR+FC+LFE+BC
+
+
‘5.1’
+
FL+FR+FC+LFE+BL+BR
+
+
‘5.1(side)’
+
FL+FR+FC+LFE+SL+SR
+
+
‘6.0’
+
FL+FR+FC+BC+SL+SR
+
+
‘6.0(front)’
+
FL+FR+FLC+FRC+SL+SR
+
+
‘hexagonal’
+
FL+FR+FC+BL+BR+BC
+
+
‘6.1’
+
FL+FR+FC+LFE+BC+SL+SR
+
+
‘6.1’
+
FL+FR+FC+LFE+BL+BR+BC
+
+
‘6.1(front)’
+
FL+FR+LFE+FLC+FRC+SL+SR
+
+
‘7.0’
+
FL+FR+FC+BL+BR+SL+SR
+
+
‘7.0(front)’
+
FL+FR+FC+FLC+FRC+SL+SR
+
+
‘7.1’
+
FL+FR+FC+LFE+BL+BR+SL+SR
+
+
‘7.1(wide)’
+
FL+FR+FC+LFE+BL+BR+FLC+FRC
+
+
‘7.1(wide-side)’
+
FL+FR+FC+LFE+FLC+FRC+SL+SR
+
+
‘octagonal’
+
FL+FR+FC+BL+BR+BC+SL+SR
+
+
‘downmix’
+
DL+DR
+
+
+
+
A custom channel layout can be specified as a sequence of terms, separated by
+’+’ or ’|’. Each term can be:
+
+
+the name of a standard channel layout (e.g. ‘mono’,
+‘stereo’, ‘4.0’, ‘quad’, ‘5.0’, etc.)
+
+
+the name of a single channel (e.g. ‘FL’, ‘FR’, ‘FC’, ‘LFE’, etc.)
+
+
+a number of channels, in decimal, optionally followed by ’c’, yielding
+the default channel layout for that number of channels (see the
+function av_get_default_channel_layout)
+
+
+a channel layout mask, in hexadecimal starting with "0x" (see the
+AV_CH_* macros in ‘libavutil/channel_layout.h’.
+
+
+
Starting from libavutil version 53 the trailing character "c" to
+specify a number of channels will be required, while a channel layout
+mask could also be specified as a decimal number (if and only if not
+followed by "c").
+
+
See also the function av_get_channel_layout defined in
+‘libavutil/channel_layout.h’.
+
When evaluating an arithmetic expression, FFmpeg uses an internal
+formula evaluator, implemented through the ‘libavutil/eval.h’
+interface.
+
+
An expression may contain unary, binary operators, constants, and
+functions.
+
+
Two expressions expr1 and expr2 can be combined to form
+another expression "expr1;expr2".
+expr1 and expr2 are evaluated in turn, and the new
+expression evaluates to the value of expr2.
+
+
The following binary operators are available: +, -,
+*, /, ^.
+
+
The following unary operators are available: +, -.
+
+
The following functions are available:
+
+
‘abs(x)’
+
Compute absolute value of x.
+
+
+
‘acos(x)’
+
Compute arccosine of x.
+
+
+
‘asin(x)’
+
Compute arcsine of x.
+
+
+
‘atan(x)’
+
Compute arctangent of x.
+
+
+
‘between(x, min, max)’
+
Return 1 if x is greater than or equal to min and lesser than or
+equal to max, 0 otherwise.
+
+
+
‘bitand(x, y)’
+
‘bitor(x, y)’
+
Compute bitwise and/or operation on x and y.
+
+
The results of the evaluation of x and y are converted to
+integers before executing the bitwise operation.
+
+
Note that both the conversion to integer and the conversion back to
+floating point can lose precision. Beware of unexpected results for
+large numbers (usually 2^53 and larger).
+
+
+
‘ceil(expr)’
+
Round the value of expression expr upwards to the nearest
+integer. For example, "ceil(1.5)" is "2.0".
+
+
+
‘cos(x)’
+
Compute cosine of x.
+
+
+
‘cosh(x)’
+
Compute hyperbolic cosine of x.
+
+
+
‘eq(x, y)’
+
Return 1 if x and y are equivalent, 0 otherwise.
+
+
+
‘exp(x)’
+
Compute exponential of x (with base e, the Euler’s number).
+
+
+
‘floor(expr)’
+
Round the value of expression expr downwards to the nearest
+integer. For example, "floor(-1.5)" is "-2.0".
+
+
+
‘gauss(x)’
+
Compute Gauss function of x, corresponding to
+exp(-x*x/2) / sqrt(2*PI).
+
+
+
‘gcd(x, y)’
+
Return the greatest common divisor of x and y. If both x and
+y are 0 or either or both are less than zero then behavior is undefined.
+
+
+
‘gt(x, y)’
+
Return 1 if x is greater than y, 0 otherwise.
+
+
+
‘gte(x, y)’
+
Return 1 if x is greater than or equal to y, 0 otherwise.
+
+
+
‘hypot(x, y)’
+
This function is similar to the C function with the same name; it returns
+"sqrt(x*x + y*y)", the length of the hypotenuse of a
+right triangle with sides of length x and y, or the distance of the
+point (x, y) from the origin.
+
+
+
‘if(x, y)’
+
Evaluate x, and if the result is non-zero return the result of
+the evaluation of y, return 0 otherwise.
+
+
+
‘if(x, y, z)’
+
Evaluate x, and if the result is non-zero return the evaluation
+result of y, otherwise the evaluation result of z.
+
+
+
‘ifnot(x, y)’
+
Evaluate x, and if the result is zero return the result of the
+evaluation of y, return 0 otherwise.
+
+
+
‘ifnot(x, y, z)’
+
Evaluate x, and if the result is zero return the evaluation
+result of y, otherwise the evaluation result of z.
+
+
+
‘isinf(x)’
+
Return 1.0 if x is +/-INFINITY, 0.0 otherwise.
+
+
+
‘isnan(x)’
+
Return 1.0 if x is NAN, 0.0 otherwise.
+
+
+
‘ld(var)’
+
Allow to load the value of the internal variable with number
+var, which was previously stored with st(var, expr).
+The function returns the loaded value.
+
+
+
‘log(x)’
+
Compute natural logarithm of x.
+
+
+
‘lt(x, y)’
+
Return 1 if x is lesser than y, 0 otherwise.
+
+
+
‘lte(x, y)’
+
Return 1 if x is lesser than or equal to y, 0 otherwise.
+
+
+
‘max(x, y)’
+
Return the maximum between x and y.
+
+
+
‘min(x, y)’
+
Return the maximum between x and y.
+
+
+
‘mod(x, y)’
+
Compute the remainder of division of x by y.
+
+
+
‘not(expr)’
+
Return 1.0 if expr is zero, 0.0 otherwise.
+
+
+
‘pow(x, y)’
+
Compute the power of x elevated y, it is equivalent to
+"(x)^(y)".
+
+
+
‘print(t)’
+
‘print(t, l)’
+
Print the value of expression t with loglevel l. If
+l is not specified then a default log level is used.
+Returns the value of the expression printed.
+
+
Prints t with loglevel l
+
+
+
‘random(x)’
+
Return a pseudo random value between 0.0 and 1.0. x is the index of the
+internal variable which will be used to save the seed/state.
+
+
+
‘root(expr, max)’
+
Find an input value for which the function represented by expr
+with argument ld(0) is 0 in the interval 0..max.
+
+
The expression in expr must denote a continuous function or the
+result is undefined.
+
+
ld(0) is used to represent the function input value, which means
+that the given expression will be evaluated multiple times with
+various input values that the expression can access through
+ld(0). When the expression evaluates to 0 then the
+corresponding input value will be returned.
+
+
+
‘sin(x)’
+
Compute sine of x.
+
+
+
‘sinh(x)’
+
Compute hyperbolic sine of x.
+
+
+
‘sqrt(expr)’
+
Compute the square root of expr. This is equivalent to
+"(expr)^.5".
+
+
+
‘squish(x)’
+
Compute expression 1/(1 + exp(4*x)).
+
+
+
‘st(var, expr)’
+
Allow to store the value of the expression expr in an internal
+variable. var specifies the number of the variable where to
+store the value, and it is a value ranging from 0 to 9. The function
+returns the value stored in the internal variable.
+Note, Variables are currently not shared between expressions.
+
+
+
‘tan(x)’
+
Compute tangent of x.
+
+
+
‘tanh(x)’
+
Compute hyperbolic tangent of x.
+
+
+
‘taylor(expr, x)’
+
‘taylor(expr, x, id)’
+
Evaluate a Taylor series at x, given an expression representing
+the ld(id)-th derivative of a function at 0.
+
+
When the series does not converge the result is undefined.
+
+
ld(id) is used to represent the derivative order in expr,
+which means that the given expression will be evaluated multiple times
+with various input values that the expression can access through
+ld(id). If id is not specified then 0 is assumed.
+
+
Note, when you have the derivatives at y instead of 0,
+taylor(expr, x-y) can be used.
+
+
+
‘time(0)’
+
Return the current (wallclock) time in seconds.
+
+
+
‘trunc(expr)’
+
Round the value of expression expr towards zero to the nearest
+integer. For example, "trunc(-1.5)" is "-1.0".
+
+
+
‘while(cond, expr)’
+
Evaluate expression expr while the expression cond is
+non-zero, and returns the value of the last expr evaluation, or
+NAN if cond was always false.
+
+
+
+
The following constants are available:
+
+
‘PI’
+
area of the unit disc, approximately 3.14
+
+
‘E’
+
exp(1) (Euler’s number), approximately 2.718
+
+
‘PHI’
+
golden ratio (1+sqrt(5))/2, approximately 1.618
+
+
+
+
Assuming that an expression is considered "true" if it has a non-zero
+value, note that:
+
+
* works like AND
+
+
+ works like OR
+
+
For example the construct:
+
if (A AND B) then C
+
+
is equivalent to:
+
if(A*B, C)
+
+
+
In your C code, you can extend the list of unary and binary functions,
+and define recognized constants, so that they are available for your
+expressions.
+
+
The evaluator also recognizes the International System unit prefixes.
+If ’i’ is appended after the prefix, binary prefixes are used, which
+are based on powers of 1024 instead of powers of 1000.
+The ’B’ postfix multiplies the value by 8, and can be appended after a
+unit prefix or used alone. This allows using for example ’KB’, ’MiB’,
+’G’ and ’B’ as number postfix.
+
+
The list of available International System prefixes follows, with
+indication of the corresponding powers of 10 and of 2.
+
libavcodec provides some generic global options, which can be set on
+all the encoders and decoders. In addition each codec may support
+so-called private options, which are specific for a given codec.
+
+
Sometimes, a global option may only affect a specific kind of codec,
+and may be unsensical or ignored by another, so you need to be aware
+of the meaning of the specified options. Also some options are
+meant only for decoding or encoding.
+
+
Options may be set by specifying -optionvalue in the
+FFmpeg tools, or by setting the value explicitly in the
+AVCodecContext options or using the ‘libavutil/opt.h’ API
+for programmatic use.
+
+
The list of supported options follow:
+
+
+
‘b integer (encoding,audio,video)’
+
Set bitrate in bits/s. Default value is 200K.
+
+
+
‘ab integer (encoding,audio)’
+
Set audio bitrate (in bits/s). Default value is 128K.
+
+
+
‘bt integer (encoding,video)’
+
Set video bitrate tolerance (in bits/s). In 1-pass mode, bitrate
+tolerance specifies how far ratecontrol is willing to deviate from the
+target average bitrate value. This is not related to min/max
+bitrate. Lowering tolerance too much has an adverse effect on quality.
+
Use internal 2pass ratecontrol in first pass mode.
+
+
‘pass2’
+
Use internal 2pass ratecontrol in second pass mode.
+
+
‘gray’
+
Only decode/encode grayscale.
+
+
‘emu_edge’
+
Do not draw edges.
+
+
‘psnr’
+
Set error[?] variables during encoding.
+
+
‘truncated’
+
‘naq’
+
Normalize adaptive quantization.
+
+
‘ildct’
+
Use interlaced DCT.
+
+
‘low_delay’
+
Force low delay.
+
+
‘global_header’
+
Place global headers in extradata instead of every keyframe.
+
+
‘bitexact’
+
Use only bitexact stuff (except (I)DCT).
+
+
‘aic’
+
Apply H263 advanced intra coding / mpeg4 ac prediction.
+
+
‘cbp’
+
Deprecated, use mpegvideo private options instead.
+
+
‘qprd’
+
Deprecated, use mpegvideo private options instead.
+
+
‘ilme’
+
Apply interlaced motion estimation.
+
+
‘cgop’
+
Use closed gop.
+
+
+
+
+
‘me_method integer (encoding,video)’
+
Set motion estimation method.
+
+
Possible values:
+
+
‘zero’
+
zero motion estimation (fastest)
+
+
‘full’
+
full motion estimation (slowest)
+
+
‘epzs’
+
EPZS motion estimation (default)
+
+
‘esa’
+
esa motion estimation (alias for full)
+
+
‘tesa’
+
tesa motion estimation
+
+
‘dia’
+
dia motion estimation (alias for epzs)
+
+
‘log’
+
log motion estimation
+
+
‘phods’
+
phods motion estimation
+
+
‘x1’
+
X1 motion estimation
+
+
‘hex’
+
hex motion estimation
+
+
‘umh’
+
umh motion estimation
+
+
‘iter’
+
iter motion estimation
+
+
+
+
+
‘extradata_size integer’
+
Set extradata size.
+
+
+
‘time_base rational number’
+
Set codec time base.
+
+
It is the fundamental unit of time (in seconds) in terms of which
+frame timestamps are represented. For fixed-fps content, timebase
+should be 1 / frame_rate and timestamp increments should be
+identically 1.
+
+
+
‘g integer (encoding,video)’
+
Set the group of picture size. Default value is 12.
+
+
+
‘ar integer (decoding/encoding,audio)’
+
Set audio sampling rate (in Hz).
+
+
+
‘ac integer (decoding/encoding,audio)’
+
Set number of audio channels.
+
+
+
‘cutoff integer (encoding,audio)’
+
Set cutoff bandwidth.
+
+
+
‘frame_size integer (encoding,audio)’
+
Set audio frame size.
+
+
Each submitted frame except the last must contain exactly frame_size
+samples per channel. May be 0 when the codec has
+CODEC_CAP_VARIABLE_FRAME_SIZE set, in that case the frame size is not
+restricted. It is set by some decoders to indicate constant frame
+size.
+
+
+
‘frame_number integer’
+
Set the frame number.
+
+
+
‘delay integer’
+
‘qcomp float (encoding,video)’
+
Set video quantizer scale compression (VBR). It is used as a constant
+in the ratecontrol equation. Recommended range for default rc_eq:
+0.0-1.0.
+
+
+
‘qblur float (encoding,video)’
+
Set video quantizer scale blur (VBR).
+
+
+
‘qmin integer (encoding,video)’
+
Set min video quantizer scale (VBR). Must be included between -1 and
+69, default value is 2.
+
+
+
‘qmax integer (encoding,video)’
+
Set max video quantizer scale (VBR). Must be included between -1 and
+1024, default value is 31.
+
+
+
‘qdiff integer (encoding,video)’
+
Set max difference between the quantizer scale (VBR).
+
+
+
‘bf integer (encoding,video)’
+
Set max number of B frames.
+
+
+
‘b_qfactor float (encoding,video)’
+
Set qp factor between P and B frames.
+
+
+
‘rc_strategy integer (encoding,video)’
+
Set ratecontrol method.
+
+
+
‘b_strategy integer (encoding,video)’
+
Set strategy to choose between I/P/B-frames.
+
+
+
‘ps integer (encoding,video)’
+
Set RTP payload size in bytes.
+
+
+
‘mv_bits integer’
+
‘header_bits integer’
+
‘i_tex_bits integer’
+
‘p_tex_bits integer’
+
‘i_count integer’
+
‘p_count integer’
+
‘skip_count integer’
+
‘misc_bits integer’
+
‘frame_bits integer’
+
‘codec_tag integer’
+
‘bug flags (decoding,video)’
+
Workaround not auto detected encoder bugs.
+
+
Possible values:
+
+
‘autodetect’
+
‘old_msmpeg4’
+
some old lavc generated msmpeg4v3 files (no autodetection)
+
+
‘xvid_ilace’
+
Xvid interlacing bug (autodetected if fourcc==XVIX)
+
+
‘ump4’
+
(autodetected if fourcc==UMP4)
+
+
‘no_padding’
+
padding bug (autodetected)
+
+
‘amv’
+
‘ac_vlc’
+
illegal vlc bug (autodetected per fourcc)
+
+
‘qpel_chroma’
+
‘std_qpel’
+
old standard qpel (autodetected per fourcc/version)
+
+
‘qpel_chroma2’
+
‘direct_blocksize’
+
direct-qpel-blocksize bug (autodetected per fourcc/version)
+
+
‘edge’
+
edge padding bug (autodetected per fourcc/version)
+
+
‘hpel_chroma’
+
‘dc_clip’
+
‘ms’
+
Workaround various bugs in microsoft broken decoders.
+
+
‘trunc’
+
trancated frames
+
+
+
+
+
‘lelim integer (encoding,video)’
+
Set single coefficient elimination threshold for luminance (negative
+values also consider DC coefficient).
+
+
+
‘celim integer (encoding,video)’
+
Set single coefficient elimination threshold for chrominance (negative
+values also consider dc coefficient)
+
+
+
‘strict integer (decoding/encoding,audio,video)’
+
Specify how strictly to follow the standards.
+
+
Possible values:
+
+
‘very’
+
strictly conform to a older more strict version of the spec or reference software
+
+
‘strict’
+
strictly conform to all the things in the spec no matter what consequences
+
+
‘normal’
+
‘unofficial’
+
allow unofficial extensions
+
+
‘experimental’
+
allow non standardized experimental things, experimental
+(unfinished/work in progress/not well tested) decoders and encoders.
+Note: experimental decoders can pose a security risk, do not use this for
+decoding untrusted input.
+
+
+
+
+
‘b_qoffset float (encoding,video)’
+
Set QP offset between P and B frames.
+
+
+
‘err_detect flags (decoding,audio,video)’
+
Set error detection flags.
+
+
Possible values:
+
+
‘crccheck’
+
verify embedded CRCs
+
+
‘bitstream’
+
detect bitstream specification deviations
+
+
‘buffer’
+
detect improper bitstream length
+
+
‘explode’
+
abort decoding on minor error detection
+
+
‘careful’
+
consider things that violate the spec and have not been seen in the wild as errors
+
+
‘compliant’
+
consider all spec non compliancies as errors
+
+
‘aggressive’
+
consider things that a sane encoder should not do as an error
+
+
+
+
+
‘has_b_frames integer’
+
‘block_align integer’
+
‘mpeg_quant integer (encoding,video)’
+
Use MPEG quantizers instead of H.263.
+
+
+
‘qsquish float (encoding,video)’
+
How to keep quantizer between qmin and qmax (0 = clip, 1 = use
+differentiable function).
+
+
+
‘rc_qmod_amp float (encoding,video)’
+
Set experimental quantizer modulation.
+
+
+
‘rc_qmod_freq integer (encoding,video)’
+
Set experimental quantizer modulation.
+
+
+
‘rc_override_count integer’
+
‘rc_eq string (encoding,video)’
+
Set rate control equation. When computing the expression, besides the
+standard functions defined in the section ’Expression Evaluation’, the
+following functions are available: bits2qp(bits), qp2bits(qp). Also
+the following constants are available: iTex pTex tex mv fCode iCount
+mcVar var isI isP isB avgQP qComp avgIITex avgPITex avgPPTex avgBPTex
+avgTex.
+
+
+
‘maxrate integer (encoding,audio,video)’
+
Set max bitrate tolerance (in bits/s). Requires bufsize to be set.
+
+
+
‘minrate integer (encoding,audio,video)’
+
Set min bitrate tolerance (in bits/s). Most useful in setting up a CBR
+encode. It is of little use elsewise.
+
+
+
‘bufsize integer (encoding,audio,video)’
+
Set ratecontrol buffer size (in bits).
+
+
+
‘rc_buf_aggressivity float (encoding,video)’
+
Currently useless.
+
+
+
‘i_qfactor float (encoding,video)’
+
Set QP factor between P and I frames.
+
+
+
‘i_qoffset float (encoding,video)’
+
Set QP offset between P and I frames.
+
+
+
‘rc_init_cplx float (encoding,video)’
+
Set initial complexity for 1-pass encoding.
+
+
+
‘dct integer (encoding,video)’
+
Set DCT algorithm.
+
+
Possible values:
+
+
‘auto’
+
autoselect a good one (default)
+
+
‘fastint’
+
fast integer
+
+
‘int’
+
accurate integer
+
+
‘mmx’
+
‘altivec’
+
‘faan’
+
floating point AAN DCT
+
+
+
+
+
‘lumi_mask float (encoding,video)’
+
Compress bright areas stronger than medium ones.
+
Number of slices, used in parallelized encoding.
+
+
+
‘thread_type flags (decoding/encoding,video)’
+
Select multithreading type.
+
+
Possible values:
+
+
‘slice’
+
‘frame’
+
+
+
‘audio_service_type integer (encoding,audio)’
+
Set audio service type.
+
+
Possible values:
+
+
‘ma’
+
Main Audio Service
+
+
‘ef’
+
Effects
+
+
‘vi’
+
Visually Impaired
+
+
‘hi’
+
Hearing Impaired
+
+
‘di’
+
Dialogue
+
+
‘co’
+
Commentary
+
+
‘em’
+
Emergency
+
+
‘vo’
+
Voice Over
+
+
‘ka’
+
Karaoke
+
+
+
+
+
‘request_sample_fmt sample_fmt (decoding,audio)’
+
Set sample format audio decoders should prefer. Default value is
+none.
+
+
+
‘pkt_timebase rational number’
+
‘sub_charenc encoding (decoding,subtitles)’
+
Set the input subtitles character encoding.
+
+
+
‘field_order field_order (video)’
+
Set/override the field order of the video.
+Possible values:
+
+
‘progressive’
+
Progressive video
+
+
‘tt’
+
Interlaced video, top field coded and displayed first
+
+
‘bb’
+
Interlaced video, bottom field coded and displayed first
+
+
‘tb’
+
Interlaced video, top coded first, bottom displayed first
+
+
‘bt’
+
Interlaced video, bottom coded first, top displayed first
+
+
+
+
+
‘skip_alpha integer (decoding,video)’
+
Set to 1 to disable processing alpha (transparency). This works like the
+‘gray’ flag in the ‘flags’ option which skips chroma information
+instead of alpha. Default is 0.
+
Decoders are configured elements in FFmpeg which allow the decoding of
+multimedia streams.
+
+
When you configure your FFmpeg build, all the supported native decoders
+are enabled by default. Decoders requiring an external library must be enabled
+manually via the corresponding --enable-lib option. You can list all
+available decoders using the configure option --list-decoders.
+
+
You can disable all the decoders with the configure option
+--disable-decoders and selectively enable / disable single decoders
+with the options --enable-decoder=DECODER /
+--disable-decoder=DECODER.
+
+
The option -codecs of the ff* tools will display the list of
+enabled decoders.
+
This decoder generates wave patterns according to predefined sequences. Its
+use is purely internal and the format of the data it accepts is not publicly
+documented.
+
libcelt allows libavcodec to decode the Xiph CELT ultra-low delay audio codec.
+Requires the presence of the libcelt headers and library during configuration.
+You need to explicitly configure the build with --enable-libcelt.
+
libgsm allows libavcodec to decode the GSM full rate audio codec. Requires
+the presence of the libgsm headers and library during configuration. You need
+to explicitly configure the build with --enable-libgsm.
+
+
This decoder supports both the ordinary GSM and the Microsoft variant.
+
libilbc allows libavcodec to decode the Internet Low Bitrate Codec (iLBC)
+audio codec. Requires the presence of the libilbc headers and library during
+configuration. You need to explicitly configure the build with
+--enable-libilbc.
+
libopencore-amrnb allows libavcodec to decode the Adaptive Multi-Rate
+Narrowband audio codec. Using it requires the presence of the
+libopencore-amrnb headers and library during configuration. You need to
+explicitly configure the build with --enable-libopencore-amrnb.
+
+
An FFmpeg native decoder for AMR-NB exists, so users can decode AMR-NB
+without this library.
+
libopencore-amrwb allows libavcodec to decode the Adaptive Multi-Rate
+Wideband audio codec. Using it requires the presence of the
+libopencore-amrwb headers and library during configuration. You need to
+explicitly configure the build with --enable-libopencore-amrwb.
+
+
An FFmpeg native decoder for AMR-WB exists, so users can decode AMR-WB
+without this library.
+
libopus allows libavcodec to decode the Opus Interactive Audio Codec.
+Requires the presence of the libopus headers and library during
+configuration. You need to explicitly configure the build with
+--enable-libopus.
+
Specify the global palette used by the bitmaps. When stored in VobSub, the
+palette is normally specified in the index file; in Matroska, the palette is
+stored in the codec extra-data in the same format as in VobSub. In DVDs, the
+palette is stored in the IFO file, and therefore not available when reading
+from dumped VOB files.
+
+
The format for this option is a string containing 16 24-bits hexadecimal
+numbers (without 0x prefix) separated by comas, for example 0d00ee,
+ee450d, 101010, eaeaea, 0ce60b, ec14ed, ebff0b, 0d617a, 7b7b7b, d1d1d1,
+7b2a0e, 0d950c, 0f007b, cf0dec, cfa80c, 7c127b.
+
Libzvbi allows libavcodec to decode DVB teletext pages and DVB teletext
+subtitles. Requires the presence of the libzvbi headers and library during
+configuration. You need to explicitly configure the build with
+--enable-libzvbi.
+
List of teletext page numbers to decode. You may use the special * string to
+match all pages. Pages that do not match the specified list are dropped.
+Default value is *.
+
+
‘txt_chop_top’
+
Discards the top teletext line. Default value is 1.
+
+
‘txt_format’
+
Specifies the format of the decoded subtitles. The teletext decoder is capable
+of decoding the teletext pages to bitmaps or to simple text, you should use
+"bitmap" for teletext pages, because certain graphics and colors cannot be
+expressed in simple text. You might use "text" for teletext based subtitles if
+your application can handle simple text based subtitles. Default value is
+bitmap.
+
+
‘txt_left’
+
X offset of generated bitmaps, default is 0.
+
+
‘txt_top’
+
Y offset of generated bitmaps, default is 0.
+
+
‘txt_chop_spaces’
+
Chops leading and trailing spaces and removes empty lines from the generated
+text. This option is useful for teletext based subtitles where empty spaces may
+be present at the start or at the end of the lines or empty lines may be
+present between the subtitle lines because of double-sized teletext charactes.
+Default value is 1.
+
+
‘txt_duration’
+
Sets the display duration of the decoded teletext pages or subtitles in
+miliseconds. Default value is 30000 which is 30 seconds.
+
+
‘txt_transparent’
+
Force transparent background of the generated teletext bitmaps. Default value
+is 0 which means an opaque (black) background.
+
Encoders are configured elements in FFmpeg which allow the encoding of
+multimedia streams.
+
+
When you configure your FFmpeg build, all the supported native encoders
+are enabled by default. Encoders requiring an external library must be enabled
+manually via the corresponding --enable-lib option. You can list all
+available encoders using the configure option --list-encoders.
+
+
You can disable all the encoders with the configure option
+--disable-encoders and selectively enable / disable single encoders
+with the options --enable-encoder=ENCODER /
+--disable-encoder=ENCODER.
+
+
The option -codecs of the ff* tools will display the list of
+enabled encoders.
+
This encoder is an experimental FFmpeg-native AAC encoder. Currently only the
+low complexity (AAC-LC) profile is supported. To use this encoder, you must set
+‘strict’ option to ‘experimental’ or lower.
+
+
As this encoder is experimental, unexpected behavior may exist from time to
+time. For a more stable AAC encoder, see libvo-aacenc. However, be warned
+that it has a worse quality reported by some users.
+
Set bit rate in bits/s. Setting this automatically activates constant bit rate
+(CBR) mode.
+
+
+
‘q’
+
Set quality for variable bit rate (VBR) mode. This option is valid only using
+the ffmpeg command-line tool. For library interface users, use
+‘global_quality’.
+
+
+
‘stereo_mode’
+
Set stereo encoding mode. Possible values:
+
+
+
‘auto’
+
Automatically selected by the encoder.
+
+
+
‘ms_off’
+
Disable middle/side encoding. This is the default.
+
+
+
‘ms_force’
+
Force middle/side encoding.
+
+
+
+
+
‘aac_coder’
+
Set AAC encoder coding method. Possible values:
+
+
+
‘faac’
+
FAAC-inspired method.
+
+
This method is a simplified reimplementation of the method used in FAAC, which
+sets thresholds proportional to the band energies, and then decreases all the
+thresholds with quantizer steps to find the appropriate quantization with
+distortion below threshold band by band.
+
+
The quality of this method is comparable to the two loop searching method
+descibed below, but somewhat a little better and slower.
+
+
+
‘anmr’
+
Average noise to mask ratio (ANMR) trellis-based solution.
+
+
This has a theoretic best quality out of all the coding methods, but at the
+cost of the slowest speed.
+
+
+
‘twoloop’
+
Two loop searching (TLS) method.
+
+
This method first sets quantizers depending on band thresholds and then tries
+to find an optimal combination by adding or subtracting a specific value from
+all quantizers and adjusting some individual quantizer a little.
+
+
This method produces similar quality with the FAAC method and is the default.
+
+
+
‘fast’
+
Constant quantizer method.
+
+
This method sets a constant quantizer for all bands. This is the fastest of all
+the methods, yet produces the worst quality.
+
These encoders implement part of ATSC A/52:2010 and ETSI TS 102 366, as well as
+the undocumented RealAudio 3 (a.k.a. dnet).
+
+
The ac3 encoder uses floating-point math, while the ac3_fixed
+encoder only uses fixed-point integer math. This does not mean that one is
+always faster, just that one or the other may be better suited to a
+particular system. The floating-point encoder will generally produce better
+quality audio for a given bitrate. The ac3_fixed encoder is not the
+default codec for any of the output formats, so it must be specified explicitly
+using the option -acodec ac3_fixed in order to use it.
+
The AC-3 metadata options are used to set parameters that describe the audio,
+but in most cases do not affect the audio encoding itself. Some of the options
+do directly affect or influence the decoding and playback of the resulting
+bitstream, while others are just for informational purposes. A few of the
+options will add bits to the output stream that could otherwise be used for
+audio data, and will thus affect the quality of the output. Those will be
+indicated accordingly with a note in the option list below.
+
+
These parameters are described in detail in several publicly-available
+documents.
+
Center Mix Level. The amount of gain the decoder should apply to the center
+channel when downmixing to stereo. This field will only be written to the
+bitstream if a center channel is present. The value is specified as a scale
+factor. There are 3 valid values:
+
+
‘0.707’
+
Apply -3dB gain
+
+
‘0.595’
+
Apply -4.5dB gain (default)
+
+
‘0.500’
+
Apply -6dB gain
+
+
+
+
+
‘-surround_mixlev level’
+
Surround Mix Level. The amount of gain the decoder should apply to the surround
+channel(s) when downmixing to stereo. This field will only be written to the
+bitstream if one or more surround channels are present. The value is specified
+as a scale factor. There are 3 valid values:
+
Audio Production Information is optional information describing the mixing
+environment. Either none or both of the fields are written to the bitstream.
+
+
+
‘-mixing_level number’
+
Mixing Level. Specifies peak sound pressure level (SPL) in the production
+environment when the mix was mastered. Valid values are 80 to 111, or -1 for
+unknown or not indicated. The default value is -1, but that value cannot be
+used if the Audio Production Information is written to the bitstream. Therefore,
+if the room_type option is not the default value, the mixing_level
+option must not be -1.
+
+
+
‘-room_type type’
+
Room Type. Describes the equalization used during the final mixing session at
+the studio or on the dubbing stage. A large room is a dubbing stage with the
+industry standard X-curve equalization; a small room has flat equalization.
+This field will not be written to the bitstream if both the mixing_level
+option and the room_type option have the default values.
+
Copyright Indicator. Specifies whether a copyright exists for this audio.
+
+
‘0’
+
‘off’
+
No Copyright Exists (default)
+
+
‘1’
+
‘on’
+
Copyright Exists
+
+
+
+
+
‘-dialnorm value’
+
Dialogue Normalization. Indicates how far the average dialogue level of the
+program is below digital 100% full scale (0 dBFS). This parameter determines a
+level shift during audio reproduction that sets the average volume of the
+dialogue to a preset level. The goal is to match volume level between program
+sources. A value of -31dB will result in no volume level change, relative to
+the source volume, during audio reproduction. Valid values are whole numbers in
+the range -31 to -1, with -31 being the default.
+
+
+
‘-dsur_mode mode’
+
Dolby Surround Mode. Specifies whether the stereo signal uses Dolby Surround
+(Pro Logic). This field will only be written to the bitstream if the audio
+stream is stereo. Using this option does NOT mean the encoder will actually
+apply Dolby Surround processing.
+
+
‘0’
+
‘notindicated’
+
Not Indicated (default)
+
+
‘1’
+
‘off’
+
Not Dolby Surround Encoded
+
+
‘2’
+
‘on’
+
Dolby Surround Encoded
+
+
+
+
+
‘-original boolean’
+
Original Bit Stream Indicator. Specifies whether this audio is from the
+original source and not a copy.
+
The extended bitstream options are part of the Alternate Bit Stream Syntax as
+specified in Annex D of the A/52:2010 standard. It is grouped into 2 parts.
+If any one parameter in a group is specified, all values in that group will be
+written to the bitstream. Default values are used for those that are written
+but have not been specified. If the mixing levels are written, the decoder
+will use these values instead of the ones specified in the center_mixlev
+and surround_mixlev options if it supports the Alternate Bit Stream
+Syntax.
+
Preferred Stereo Downmix Mode. Allows the user to select either Lt/Rt
+(Dolby Surround) or Lo/Ro (normal stereo) as the preferred stereo downmix mode.
+
+
‘0’
+
‘notindicated’
+
Not Indicated (default)
+
+
‘1’
+
‘ltrt’
+
Lt/Rt Downmix Preferred
+
+
‘2’
+
‘loro’
+
Lo/Ro Downmix Preferred
+
+
+
+
+
‘-ltrt_cmixlev level’
+
Lt/Rt Center Mix Level. The amount of gain the decoder should apply to the
+center channel when downmixing to stereo in Lt/Rt mode.
+
+
‘1.414’
+
Apply +3dB gain
+
+
‘1.189’
+
Apply +1.5dB gain
+
+
‘1.000’
+
Apply 0dB gain
+
+
‘0.841’
+
Apply -1.5dB gain
+
+
‘0.707’
+
Apply -3.0dB gain
+
+
‘0.595’
+
Apply -4.5dB gain (default)
+
+
‘0.500’
+
Apply -6.0dB gain
+
+
‘0.000’
+
Silence Center Channel
+
+
+
+
+
‘-ltrt_surmixlev level’
+
Lt/Rt Surround Mix Level. The amount of gain the decoder should apply to the
+surround channel(s) when downmixing to stereo in Lt/Rt mode.
+
+
‘0.841’
+
Apply -1.5dB gain
+
+
‘0.707’
+
Apply -3.0dB gain
+
+
‘0.595’
+
Apply -4.5dB gain
+
+
‘0.500’
+
Apply -6.0dB gain (default)
+
+
‘0.000’
+
Silence Surround Channel(s)
+
+
+
+
+
‘-loro_cmixlev level’
+
Lo/Ro Center Mix Level. The amount of gain the decoder should apply to the
+center channel when downmixing to stereo in Lo/Ro mode.
+
+
‘1.414’
+
Apply +3dB gain
+
+
‘1.189’
+
Apply +1.5dB gain
+
+
‘1.000’
+
Apply 0dB gain
+
+
‘0.841’
+
Apply -1.5dB gain
+
+
‘0.707’
+
Apply -3.0dB gain
+
+
‘0.595’
+
Apply -4.5dB gain (default)
+
+
‘0.500’
+
Apply -6.0dB gain
+
+
‘0.000’
+
Silence Center Channel
+
+
+
+
+
‘-loro_surmixlev level’
+
Lo/Ro Surround Mix Level. The amount of gain the decoder should apply to the
+surround channel(s) when downmixing to stereo in Lo/Ro mode.
+
Dolby Surround EX Mode. Indicates whether the stream uses Dolby Surround EX
+(7.1 matrixed to 5.1). Using this option does NOT mean the encoder will actually
+apply Dolby Surround EX processing.
+
+
‘0’
+
‘notindicated’
+
Not Indicated (default)
+
+
‘1’
+
‘on’
+
Dolby Surround EX Off
+
+
‘2’
+
‘off’
+
Dolby Surround EX On
+
+
+
+
+
‘-dheadphone_mode mode’
+
Dolby Headphone Mode. Indicates whether the stream uses Dolby Headphone
+encoding (multi-channel matrixed to 2.0 for use with headphones). Using this
+option does NOT mean the encoder will actually apply Dolby Headphone
+processing.
+
+
‘0’
+
‘notindicated’
+
Not Indicated (default)
+
+
‘1’
+
‘on’
+
Dolby Headphone Off
+
+
‘2’
+
‘off’
+
Dolby Headphone On
+
+
+
+
+
‘-ad_conv_type type’
+
A/D Converter Type. Indicates whether the audio has passed through HDCD A/D
+conversion.
+
Stereo Rematrixing. Enables/Disables use of rematrixing for stereo input. This
+is an optional AC-3 feature that increases quality by selectively encoding
+the left/right channels as mid/side. This option is enabled by default, and it
+is highly recommended that it be left as enabled except for testing purposes.
+
These options are only valid for the floating-point encoder and do not exist
+for the fixed-point encoder due to the corresponding features not being
+implemented in fixed-point.
+
+
+
‘-channel_coupling boolean’
+
Enables/Disables use of channel coupling, which is an optional AC-3 feature
+that increases quality by combining high frequency information from multiple
+channels into a single channel. The per-channel high frequency information is
+sent with less accuracy in both the frequency and time domains. This allows
+more bits to be used for lower frequencies while preserving enough information
+to reconstruct the high frequencies. This option is enabled by default for the
+floating-point encoder and should generally be left as enabled except for
+testing purposes or to increase encoding speed.
+
+
‘-1’
+
‘auto’
+
Selected by Encoder (default)
+
+
‘0’
+
‘off’
+
Disable Channel Coupling
+
+
‘1’
+
‘on’
+
Enable Channel Coupling
+
+
+
+
+
‘-cpl_start_band number’
+
Coupling Start Band. Sets the channel coupling start band, from 1 to 15. If a
+value higher than the bandwidth is used, it will be reduced to 1 less than the
+coupling end band. If auto is used, the start band will be determined by
+the encoder based on the bit rate, sample rate, and channel layout. This option
+has no effect if channel coupling is disabled.
+
LAME (Lame Ain’t an MP3 Encoder) MP3 encoder wrapper.
+
+
Requires the presence of the libmp3lame headers and library during
+configuration. You need to explicitly configure the build with
+--enable-libmp3lame.
+
+
See libshine for a fixed-point MP3 encoder, although with a
+lower quality.
+
The following options are supported by the libmp3lame wrapper. The
+lame-equivalent of the options are listed in parentheses.
+
+
+
‘b (-b)’
+
Set bitrate expressed in bits/s for CBR. LAME bitrate is
+expressed in kilobits/s.
+
+
+
‘q (-V)’
+
Set constant quality setting for VBR. This option is valid only
+using the ffmpeg command-line tool. For library interface
+users, use ‘global_quality’.
+
+
+
‘compression_level (-q)’
+
Set algorithm quality. Valid arguments are integers in the 0-9 range,
+with 0 meaning highest quality but slowest, and 9 meaning fastest
+while producing the worst quality.
+
+
+
‘reservoir’
+
Enable use of bit reservoir when set to 1. Default value is 1. LAME
+has this enabled by default, but can be overriden by use
+‘--nores’ option.
+
+
+
‘joint_stereo (-m j)’
+
Enable the encoder to use (on a frame by frame basis) either L/R
+stereo or mid/side stereo. Default value is 1.
+
Requires the presence of the libopencore-amrnb headers and library during
+configuration. You need to explicitly configure the build with
+--enable-libopencore-amrnb --enable-version3.
+
+
This is a mono-only encoder. Officially it only supports 8000Hz sample rate,
+but you can override it by setting ‘strict’ to ‘unofficial’ or
+lower.
+
Shine is a fixed-point MP3 encoder. It has a far better performance on
+platforms without an FPU, e.g. armel CPUs, and some phones and tablets.
+However, as it is more targeted on performance than quality, it is not on par
+with LAME and other production-grade encoders quality-wise. Also, according to
+the project’s homepage, this encoder may not be free of bugs as the code was
+written a long time ago and the project was dead for at least 5 years.
+
+
This encoder only supports stereo and mono input. This is also CBR-only.
+
Requires the presence of the libtwolame headers and library during
+configuration. You need to explicitly configure the build with
+--enable-libtwolame.
+
The following options are supported by the libtwolame wrapper. The
+twolame-equivalent options follow the FFmpeg ones and are in
+parentheses.
+
+
+
‘b (-b)’
+
Set bitrate expressed in bits/s for CBR. twolame ‘b’
+option is expressed in kilobits/s. Default value is 128k.
+
+
+
‘q (-V)’
+
Set quality for experimental VBR support. Maximum value range is
+from -50 to 50, useful range is from -10 to 10. The higher the
+value, the better the quality. This option is valid only using the
+ffmpeg command-line tool. For library interface users,
+use ‘global_quality’.
+
+
+
‘mode (--mode)’
+
Set the mode of the resulting audio. Possible values:
+
+
+
‘auto’
+
Choose mode automatically based on the input. This is the default.
+
+
‘stereo’
+
Stereo
+
+
‘joint_stereo’
+
Joint stereo
+
+
‘dual_channel’
+
Dual channel
+
+
‘mono’
+
Mono
+
+
+
+
+
‘psymodel (--psyc-mode)’
+
Set psychoacoustic model to use in encoding. The argument must be
+an integer between -1 and 4, inclusive. The higher the value, the
+better the quality. The default value is 3.
+
+
+
‘energy_levels (--energy)’
+
Enable energy levels extensions when set to 1. The default value is
+0 (disabled).
+
+
+
‘error_protection (--protect)’
+
Enable CRC error protection when set to 1. The default value is 0
+(disabled).
+
+
+
‘copyright (--copyright)’
+
Set MPEG audio copyright flag when set to 1. The default value is 0
+(disabled).
+
+
+
‘original (--original)’
+
Set MPEG audio original flag when set to 1. The default value is 0
+(disabled).
+
Requires the presence of the libvo-aacenc headers and library during
+configuration. You need to explicitly configure the build with
+--enable-libvo-aacenc --enable-version3.
+
Requires the presence of the libvo-amrwbenc headers and library during
+configuration. You need to explicitly configure the build with
+--enable-libvo-amrwbenc --enable-version3.
+
+
This is a mono-only encoder. Officially it only supports 16000Hz sample
+rate, but you can override it by setting ‘strict’ to
+‘unofficial’ or lower.
+
Most libopus options are modeled after the opusenc utility from
+opus-tools. The following is an option mapping chart describing options
+supported by the libopus wrapper, and their opusenc-equivalent
+in parentheses.
+
+
+
‘b (bitrate)’
+
Set the bit rate in bits/s. FFmpeg’s ‘b’ option is
+expressed in bits/s, while opusenc’s ‘bitrate’ in
+kilobits/s.
+
+
+
‘vbr (vbr, hard-cbr, and cvbr)’
+
Set VBR mode. The FFmpeg ‘vbr’ option has the following
+valid arguments, with the their opusenc equivalent options
+in parentheses:
+
+
+
‘off (hard-cbr)’
+
Use constant bit rate encoding.
+
+
+
‘on (vbr)’
+
Use variable bit rate encoding (the default).
+
+
+
‘constrained (cvbr)’
+
Use constrained variable bit rate encoding.
+
+
+
+
+
‘compression_level (comp)’
+
Set encoding algorithm complexity. Valid options are integers in
+the 0-10 range. 0 gives the fastest encodes but lower quality, while 10
+gives the highest quality but slowest encoding. The default is 10.
+
+
+
‘frame_duration (framesize)’
+
Set maximum frame size, or duration of a frame in milliseconds. The
+argument must be exactly the following: 2.5, 5, 10, 20, 40, 60. Smaller
+frame sizes achieve lower latency but less quality at a given bitrate.
+Sizes greater than 20ms are only interesting at fairly low bitrates.
+The default is 20ms.
+
+
+
‘packet_loss (expect-loss)’
+
Set expected packet loss percentage. The default is 0.
+
+
+
‘application (N.A.)’
+
Set intended application type. Valid options are listed below:
+
+
+
‘voip’
+
Favor improved speech intelligibility.
+
+
‘audio’
+
Favor faithfulness to the input (the default).
+
+
‘lowdelay’
+
Restrict to only the lowest delay modes.
+
+
+
+
+
‘cutoff (N.A.)’
+
Set cutoff bandwidth in Hz. The argument must be exactly one of the
+following: 4000, 6000, 8000, 12000, or 20000, corresponding to
+narrowband, mediumband, wideband, super wideband, and fullband
+respectively. The default is 0 (cutoff disabled).
+
Requires the presence of the libvorbisenc headers and library during
+configuration. You need to explicitly configure the build with
+--enable-libvorbis.
+
Set bitrate expressed in bits/s for ABR. oggenc ‘-b’ is
+expressed in kilobits/s.
+
+
+
‘q (-q)’
+
Set constant quality setting for VBR. The value should be a float
+number in the range of -1.0 to 10.0. The higher the value, the better
+the quality. The default value is ‘3.0’.
+
+
This option is valid only using the ffmpeg command-line tool.
+For library interface users, use ‘global_quality’.
+
Set noise floor bias for impulse blocks. The value is a float number from
+-15.0 to 0.0. A negative bias instructs the encoder to pay special attention
+to the crispness of transients in the encoded audio. The tradeoff for better
+transient response is a higher bitrate.
+
A wrapper providing WavPack encoding through libwavpack.
+
+
Only lossless mode using 32-bit integer samples is supported currently.
+The ‘compression_level’ option can be used to control speed vs.
+compression tradeoff, with the values mapped to libwavpack as follows:
+
+
+
‘0’
+
Fast mode - corresponding to the wavpack ‘-f’ option.
+
+
+
‘1’
+
Normal (default) settings.
+
+
+
‘2’
+
High quality - corresponding to the wavpack ‘-h’ option.
+
+
+
‘3’
+
Very high quality - corresponding to the wavpack ‘-hh’ option.
+
+
+
‘4-8’
+
Same as 3, but with extra processing enabled - corresponding to the wavpack
+‘-x’ option. I.e. 4 is the same as ‘-x2’ and 8 is the same as
+‘-x6’.
+
Requires the presence of the libtheora headers and library during
+configuration. You need to explicitly configure the build with
+--enable-libtheora.
+
The following global options are mapped to internal libtheora options
+which affect the quality and the bitrate of the encoded stream.
+
+
+
‘b’
+
Set the video bitrate, only works if the qscale flag in
+‘flags’ is not enabled.
+
+
+
‘flags’
+
Used to enable constant quality mode encoding through the
+‘qscale’ flag, and to enable the pass1 and pass2
+modes.
+
+
+
‘g’
+
Set the GOP size.
+
+
+
‘global_quality’
+
Set the global quality in lambda units, only works if the
+qscale flag in ‘flags’ is enabled. The value is clipped
+in the [0 - 10*FF_QP2LAMBDA] range, and then multiplied for 6.3
+to get a value in the native libtheora range [0-63]. A higher value
+corresponds to a higher quality.
+
+
For example, to set maximum constant quality encoding with
+ffmpeg:
+
This encoder requires the presence of the libx264 headers and library
+during configuration. You need to explicitly configure the build with
+--enable-libx264.
+
+
libx264 supports an impressive number of features, including 8x8 and
+4x4 adaptive spatial transform, adaptive B-frame placement, CAVLC/CABAC
+entropy coding, interlacing (MBAFF), lossless mode, psy optimizations
+for detail retention (adaptive quantization, psy-RD, psy-trellis).
+
+
Many libx264 encoder options are mapped to FFmpeg global codec
+options, while unique encoder options are provided through private
+options. Additionally the ‘x264opts’ and ‘x264-params’
+private options allows to pass a list of key=value tuples as accepted
+by the libx264 x264_param_parse function.
+
The following options are supported by the libx264 wrapper. The
+x264-equivalent options or values are listed in parentheses
+for easy migration.
+
+
To reduce the duplication of documentation, only the private options
+and some others requiring special attention are documented here. For
+the documentation of the undocumented generic options, see
+the Codec Options chapter.
+
+
To get a more accurate and extensive documentation of the libx264
+options, invoke the command x264 --full-help or consult
+the libx264 documentation.
+
+
+
‘b (bitrate)’
+
Set bitrate in bits/s. Note that FFmpeg’s ‘b’ option is
+expressed in bits/s, while x264’s ‘bitrate’ is in
+kilobits/s.
+
+
+
‘bf (bframes)’
+
‘g (keyint)’
+
‘qmax (qpmax)’
+
‘qmin (qpmin)’
+
‘qdiff (qpstep)’
+
‘qblur (qblur)’
+
‘qcomp (qcomp)’
+
‘refs (ref)’
+
‘sc_threshold (scenecut)’
+
‘trellis (trellis)’
+
‘nr (nr)’
+
‘me_range (merange)’
+
‘me_method (me)’
+
Set motion estimation method. Possible values in the decreasing order
+of speed:
+
+
+
‘dia (dia)’
+
‘epzs (dia)’
+
Diamond search with radius 1 (fastest). ‘epzs’ is an alias for
+‘dia’.
+
+
‘hex (hex)’
+
Hexagonal search with radius 2.
+
+
‘umh (umh)’
+
Uneven multi-hexagon search.
+
+
‘esa (esa)’
+
Exhaustive search.
+
+
‘tesa (tesa)’
+
Hadamard exhaustive search (slowest).
+
+
+
+
+
‘subq (subme)’
+
‘b_strategy (b-adapt)’
+
‘keyint_min (min-keyint)’
+
‘coder’
+
Set entropy encoder. Possible values:
+
+
+
‘ac’
+
Enable CABAC.
+
+
+
‘vlc’
+
Enable CAVLC and disable CABAC. It generates the same effect as
+x264’s ‘--no-cabac’ option.
+
+
+
+
+
‘cmp’
+
Set full pixel motion estimation comparation algorithm. Possible values:
+
+
+
‘chroma’
+
Enable chroma in motion estimation.
+
+
+
‘sad’
+
Ignore chroma in motion estimation. It generates the same effect as
+x264’s ‘--no-chroma-me’ option.
+
+
+
+
+
‘threads (threads)’
+
‘thread_type’
+
Set multithreading technique. Possible values:
+
+
+
‘slice’
+
Slice-based multithreading. It generates the same effect as
+x264’s ‘--sliced-threads’ option.
+
+
‘frame’
+
Frame-based multithreading.
+
+
+
+
+
‘flags’
+
Set encoding flags. It can be used to disable closed GOP and enable
+open GOP by setting it to -cgop. The result is similar to
+the behavior of x264’s ‘--open-gop’ option.
+
+
+
‘rc_init_occupancy (vbv-init)’
+
‘preset (preset)’
+
Set the encoding preset.
+
+
+
‘tune (tune)’
+
Set tuning of the encoding params.
+
+
+
‘profile (profile)’
+
Set profile restrictions.
+
+
+
‘fastfirstpass’
+
Enable fast settings when encoding first pass, when set to 1. When set
+to 0, it has the same effect of x264’s
+‘--slow-firstpass’ option.
+
+
+
‘crf (crf)’
+
Set the quality for constant quality mode.
+
+
+
‘crf_max (crf-max)’
+
In CRF mode, prevents VBV from lowering quality beyond this point.
+
+
+
‘qp (qp)’
+
Set constant quantization rate control method parameter.
+
+
+
‘aq-mode (aq-mode)’
+
Set AQ method. Possible values:
+
+
+
‘none (0)’
+
Disabled.
+
+
+
‘variance (1)’
+
Variance AQ (complexity mask).
+
+
+
‘autovariance (2)’
+
Auto-variance AQ (experimental).
+
+
+
+
+
‘aq-strength (aq-strength)’
+
Set AQ strength, reduce blocking and blurring in flat and textured areas.
+
+
+
‘psy’
+
Use psychovisual optimizations when set to 1. When set to 0, it has the
+same effect as x264’s ‘--no-psy’ option.
+
+
+
‘psy-rd (psy-rd)’
+
Set strength of psychovisual optimization, in
+psy-rd:psy-trellis format.
+
+
+
‘rc-lookahead (rc-lookahead)’
+
Set number of frames to look ahead for frametype and ratecontrol.
+
+
+
‘weightb’
+
Enable weighted prediction for B-frames when set to 1. When set to 0,
+it has the same effect as x264’s ‘--no-weightb’ option.
+
+
+
‘weightp (weightp)’
+
Set weighted prediction method for P-frames. Possible values:
+
+
+
‘none (0)’
+
Disabled
+
+
‘simple (1)’
+
Enable only weighted refs
+
+
‘smart (2)’
+
Enable both weighted refs and duplicates
+
+
+
+
+
‘ssim (ssim)’
+
Enable calculation and printing SSIM stats after the encoding.
+
+
+
‘intra-refresh (intra-refresh)’
+
Enable the use of Periodic Intra Refresh instead of IDR frames when set
+to 1.
+
+
+
‘bluray-compat (bluray-compat)’
+
Configure the encoder to be compatible with the bluray standard.
+It is a shorthand for setting "bluray-compat=1 force-cfr=1".
+
+
+
‘b-bias (b-bias)’
+
Set the influence on how often B-frames are used.
+
+
+
‘b-pyramid (b-pyramid)’
+
Set method for keeping of some B-frames as references. Possible values:
+
+
+
‘none (none)’
+
Disabled.
+
+
‘strict (strict)’
+
Strictly hierarchical pyramid.
+
+
‘normal (normal)’
+
Non-strict (not Blu-ray compatible).
+
+
+
+
+
‘mixed-refs’
+
Enable the use of one reference per partition, as opposed to one
+reference per macroblock when set to 1. When set to 0, it has the
+same effect as x264’s ‘--no-mixed-refs’ option.
+
+
+
‘8x8dct’
+
Enable adaptive spatial transform (high profile 8x8 transform)
+when set to 1. When set to 0, it has the same effect as
+x264’s ‘--no-8x8dct’ option.
+
+
+
‘fast-pskip’
+
Enable early SKIP detection on P-frames when set to 1. When set
+to 0, it has the same effect as x264’s
+‘--no-fast-pskip’ option.
+
+
+
‘aud (aud)’
+
Enable use of access unit delimiters when set to 1.
+
+
+
‘mbtree’
+
Enable use macroblock tree ratecontrol when set to 1. When set
+to 0, it has the same effect as x264’s
+‘--no-mbtree’ option.
+
+
+
‘deblock (deblock)’
+
Set loop filter parameters, in alpha:beta form.
+
+
+
‘cplxblur (cplxblur)’
+
Set fluctuations reduction in QP (before curve compression).
+
+
+
‘partitions (partitions)’
+
Set partitions to consider as a comma-separated list of. Possible
+values in the list:
+
+
+
‘p8x8’
+
8x8 P-frame partition.
+
+
‘p4x4’
+
4x4 P-frame partition.
+
+
‘b8x8’
+
4x4 B-frame partition.
+
+
‘i8x8’
+
8x8 I-frame partition.
+
+
‘i4x4’
+
4x4 I-frame partition.
+(Enabling ‘p4x4’ requires ‘p8x8’ to be enabled. Enabling
+‘i8x8’ requires adaptive spatial transform (‘8x8dct’
+option) to be enabled.)
+
+
‘none (none)’
+
Do not consider any partitions.
+
+
‘all (all)’
+
Consider every partition.
+
+
+
+
+
‘direct-pred (direct)’
+
Set direct MV prediction mode. Possible values:
+
+
+
‘none (none)’
+
Disable MV prediction.
+
+
‘spatial (spatial)’
+
Enable spatial predicting.
+
+
‘temporal (temporal)’
+
Enable temporal predicting.
+
+
‘auto (auto)’
+
Automatically decided.
+
+
+
+
+
‘slice-max-size (slice-max-size)’
+
Set the limit of the size of each slice in bytes. If not specified
+but RTP payload size (‘ps’) is specified, that is used.
+
+
+
‘stats (stats)’
+
Set the file name for multi-pass stats.
+
+
+
‘nal-hrd (nal-hrd)’
+
Set signal HRD information (requires ‘vbv-bufsize’ to be set).
+Possible values:
+
+
+
‘none (none)’
+
Disable HRD information signaling.
+
+
‘vbr (vbr)’
+
Variable bit rate.
+
+
‘cbr (cbr)’
+
Constant bit rate (not allowed in MP4 container).
+
+
+
+
+
‘x264opts (N.A.)’
+
Set any x264 option, see x264 --fullhelp for a list.
+
+
Argument is a list of key=value couples separated by
+":". In filter and psy-rd options that use ":" as a separator
+themselves, use "," instead. They accept it as well since long ago but this
+is kept undocumented for some reason.
+
+
For example to specify libx264 encoding options with ffmpeg:
+
This encoder requires the presence of the libxvidcore headers and library
+during configuration. You need to explicitly configure the build with
+--enable-libxvid --enable-gpl.
+
+
The native mpeg4 encoder supports the MPEG-4 Part 2 format, so
+users can encode to this format without this library.
+
The following options are supported by the libxvid wrapper. Some of
+the following options are listed but are not documented, and
+correspond to shared codec options. See the Codec Options chapter for their documentation. The other shared options
+which are not listed have no effect for the libxvid encoder.
+
+
+
‘b’
+
‘g’
+
‘qmin’
+
‘qmax’
+
‘mpeg_quant’
+
‘threads’
+
‘bf’
+
‘b_qfactor’
+
‘b_qoffset’
+
‘flags’
+
Set specific encoding flags. Possible values:
+
+
+
‘mv4’
+
Use four motion vector by macroblock.
+
+
+
‘aic’
+
Enable high quality AC prediction.
+
+
+
‘gray’
+
Only encode grayscale.
+
+
+
‘gmc’
+
Enable the use of global motion compensation (GMC).
+
+
+
‘qpel’
+
Enable quarter-pixel motion compensation.
+
+
+
‘cgop’
+
Enable closed GOP.
+
+
+
‘global_header’
+
Place global headers in extradata instead of every keyframe.
+
+
+
+
+
+
‘trellis’
+
‘me_method’
+
Set motion estimation method. Possible values in decreasing order of
+speed and increasing order of quality:
+
+
+
‘zero’
+
Use no motion estimation (default).
+
+
+
‘phods’
+
‘x1’
+
‘log’
+
Enable advanced diamond zonal search for 16x16 blocks and half-pixel
+refinement for 16x16 blocks. ‘x1’ and ‘log’ are aliases for
+‘phods’.
+
+
+
‘epzs’
+
Enable all of the things described above, plus advanced diamond zonal
+search for 8x8 blocks, half-pixel refinement for 8x8 blocks, and motion
+estimation on chroma planes.
+
+
+
‘full’
+
Enable all of the things described above, plus extended 16x16 and 8x8
+blocks search.
+
+
+
+
+
‘mbd’
+
Set macroblock decision algorithm. Possible values in the increasing
+order of quality:
+
+
+
‘simple’
+
Use macroblock comparing function algorithm (default).
+
+
+
‘bits’
+
Enable rate distortion-based half pixel and quarter pixel refinement for
+16x16 blocks.
+
+
+
‘rd’
+
Enable all of the things described above, plus rate distortion-based
+half pixel and quarter pixel refinement for 8x8 blocks, and rate
+distortion-based search using square pattern.
+
+
+
+
+
‘lumi_aq’
+
Enable lumi masking adaptive quantization when set to 1. Default is 0
+(disabled).
+
+
+
‘variance_aq’
+
Enable variance adaptive quantization when set to 1. Default is 0
+(disabled).
+
+
When combined with ‘lumi_aq’, the resulting quality will not
+be better than any of the two specified individually. In other
+words, the resulting quality will be the worse one of the two
+effects.
+
+
+
‘ssim’
+
Set structural similarity (SSIM) displaying method. Possible values:
+
+
+
‘off’
+
Disable displaying of SSIM information.
+
+
+
‘avg’
+
Output average SSIM at the end of encoding to stdout. The format of
+showing the average SSIM is:
+
+
Average SSIM: %f
+
+
+
For users who are not familiar with C, %f means a float number, or
+a decimal (e.g. 0.939232).
+
+
+
‘frame’
+
Output both per-frame SSIM data during encoding and average SSIM at
+the end of encoding to stdout. The format of per-frame information
+is:
+
+
SSIM: avg: %1.3f min: %1.3f max: %1.3f
+
+
+
For users who are not familiar with C, %1.3f means a float number
+rounded to 3 digits after the dot (e.g. 0.932).
+
+
+
+
+
+
‘ssim_acc’
+
Set SSIM accuracy. Valid options are integers within the range of
+0-4, while 0 gives the most accurate result and 4 computes the
+fastest.
+
In the default mode of operation the encoder has to honor frame constraints
+(i.e. not produc frames with size bigger than requested) while still making
+output picture as good as possible.
+A frame containing a lot of small details is harder to compress and the encoder
+would spend more time searching for appropriate quantizers for each slice.
+
+
Setting a higher ‘bits_per_mb’ limit will improve the speed.
+
+
For the fastest encoding speed set the ‘qscale’ parameter (4 is the
+recommended value) and do not set a size constraint.
+
When you configure your FFmpeg build, all the supported bitstream
+filters are enabled by default. You can list all available ones using
+the configure option --list-bsfs.
+
+
You can disable all the bitstream filters using the configure option
+--disable-bsfs, and selectively enable any bitstream filter using
+the option --enable-bsf=BSF, or you can disable a particular
+bitstream filter using the option --disable-bsf=BSF.
+
+
The option -bsfs of the ff* tools will display the list of
+all the supported bitstream filters included in your build.
+
+
Below is a description of the currently available bitstream filters.
+
Add extradata to the beginning of the filtered packets.
+
+
The additional argument specifies which packets should be filtered.
+It accepts the values:
+
+
‘a’
+
add extradata to all key packets, but only if local_header is
+set in the ‘flags2’ codec context field
+
+
+
‘k’
+
add extradata to all key packets
+
+
+
‘e’
+
add extradata to all packets
+
+
+
+
If not specified it is assumed ‘k’.
+
+
For example the following ffmpeg command forces a global
+header (thus disabling individual packet headers) in the H.264 packets
+generated by the libx264 encoder, but corrects them by adding
+the header stored in extradata to the key packets:
+
Avery Lee, writing in the rec.video.desktop newsgroup in 2001,
+commented that "MJPEG, or at least the MJPEG in AVIs having the
+MJPG fourcc, is restricted JPEG with a fixed – and *omitted* –
+Huffman table. The JPEG must be YCbCr colorspace, it must be 4:2:2,
+and it must use basic Huffman encoding, not arithmetic or
+progressive. . . . You can indeed extract the MJPEG frames and
+decode them with a regular JPEG decoder, but you have to prepend
+the DHT segment to them, or else the decoder won’t have any idea
+how to decompress the data. The exact table necessary is given in
+the OpenDML spec."
+
+
This bitstream filter patches the header of frames extracted from an MJPEG
+stream (carrying the AVI1 header ID and lacking a DHT segment) to
+produce fully qualified JPEG images.
+
The libavformat library provides some generic global options, which
+can be set on all the muxers and demuxers. In addition each muxer or
+demuxer may support so-called private options, which are specific for
+that component.
+
+
Options may be set by specifying -optionvalue in the
+FFmpeg tools, or by setting the value explicitly in the
+AVFormatContext options or using the ‘libavutil/opt.h’ API
+for programmatic use.
+
+
The list of supported options follows:
+
+
+
‘avioflags flags (input/output)’
+
Possible values:
+
+
‘direct’
+
Reduce buffering.
+
+
+
+
+
‘probesize integer (input)’
+
Set probing size in bytes, i.e. the size of the data to analyze to get
+stream information. A higher value will allow to detect more
+information in case it is dispersed into the stream, but will increase
+latency. Must be an integer not lesser than 32. It is 5000000 by default.
+
+
+
‘packetsize integer (output)’
+
Set packet size.
+
+
+
‘fflags flags (input/output)’
+
Set format flags.
+
+
Possible values:
+
+
‘ignidx’
+
Ignore index.
+
+
‘genpts’
+
Generate PTS.
+
+
‘nofillin’
+
Do not fill in missing values that can be exactly calculated.
+
+
‘noparse’
+
Disable AVParsers, this needs +nofillin too.
+
+
‘igndts’
+
Ignore DTS.
+
+
‘discardcorrupt’
+
Discard corrupted frames.
+
+
‘sortdts’
+
Try to interleave output packets by DTS.
+
+
‘keepside’
+
Do not merge side data.
+
+
‘latm’
+
Enable RTP MP4A-LATM payload.
+
+
‘nobuffer’
+
Reduce the latency introduced by optional buffering
+
+
+
+
+
‘seek2any integer (input)’
+
Allow seeking to non-keyframes on demuxer level when supported if set to 1.
+Default is 0.
+
+
+
‘analyzeduration integer (input)’
+
Specify how many microseconds are analyzed to probe the input. A
+higher value will allow to detect more accurate information, but will
+increase latency. It defaults to 5,000,000 microseconds = 5 seconds.
+
+
+
‘cryptokey hexadecimal string (input)’
+
Set decryption key.
+
+
+
‘indexmem integer (input)’
+
Set max memory used for timestamp index (per stream).
+
+
+
‘rtbufsize integer (input)’
+
Set max memory used for buffering real-time frames.
+
+
+
‘fdebug flags (input/output)’
+
Print specific debug info.
+
+
Possible values:
+
+
‘ts’
+
+
+
+
‘max_delay integer (input/output)’
+
Set maximum muxing or demuxing delay in microseconds.
+
+
+
‘fpsprobesize integer (input)’
+
Set number of frames used to probe fps.
+
+
+
‘audio_preload integer (output)’
+
Set microseconds by which audio packets should be interleaved earlier.
+
+
+
‘chunk_duration integer (output)’
+
Set microseconds for each chunk.
+
+
+
‘chunk_size integer (output)’
+
Set size in bytes for each chunk.
+
+
+
‘err_detect, f_err_detect flags (input)’
+
Set error detection flags. f_err_detect is deprecated and
+should be used only via the ffmpeg tool.
+
+
Possible values:
+
+
‘crccheck’
+
Verify embedded CRCs.
+
+
‘bitstream’
+
Detect bitstream specification deviations.
+
+
‘buffer’
+
Detect improper bitstream length.
+
+
‘explode’
+
Abort decoding on minor error detection.
+
+
‘careful’
+
Consider things that violate the spec and have not been seen in the
+wild as errors.
+
+
‘compliant’
+
Consider all spec non compliancies as errors.
+
+
‘aggressive’
+
Consider things that a sane encoder should not do as an error.
+
+
+
+
+
‘use_wallclock_as_timestamps integer (input)’
+
Use wallclock as timestamps.
+
+
+
‘avoid_negative_ts integer (output)’
+
Shift timestamps to make them non-negative. A value of 1 enables shifting,
+a value of 0 disables it, the default value of -1 enables shifting
+when required by the target format.
+
+
When shifting is enabled, all output timestamps are shifted by the
+same amount. Audio, video, and subtitles desynching and relative
+timestamp differences are preserved compared to how they would have
+been without shifting.
+
+
Also note that this affects only leading negative timestamps, and not
+non-monotonic negative timestamps.
+
+
+
‘skip_initial_bytes integer (input)’
+
Set number of bytes to skip before reading header and frames if set to 1.
+Default is 0.
+
+
+
‘correct_ts_overflow integer (input)’
+
Correct single timestamp overflows if set to 1. Default is 1.
+
+
+
‘flush_packets integer (output)’
+
Flush the underlying I/O stream after each packet. Default 1 enables it, and
+has the effect of reducing the latency; 0 disables it and may slightly
+increase performance in some cases.
+
Format stream specifiers allow selection of one or more streams that
+match specific properties.
+
+
Possible forms of stream specifiers are:
+
+
‘stream_index’
+
Matches the stream with this index.
+
+
+
‘stream_type[:stream_index]’
+
stream_type is one of following: ’v’ for video, ’a’ for audio,
+’s’ for subtitle, ’d’ for data, and ’t’ for attachments. If
+stream_index is given, then it matches the stream number
+stream_index of this type. Otherwise, it matches all streams of
+this type.
+
+
+
‘p:program_id[:stream_index]’
+
If stream_index is given, then it matches the stream with number
+stream_index in the program with the id
+program_id. Otherwise, it matches all streams in the program.
+
+
+
‘#stream_id’
+
Matches the stream by a format-specific ID.
+
+
+
+
The exact semantics of stream specifiers is defined by the
+avformat_match_stream_specifier() function declared in the
+‘libavformat/avformat.h’ header.
+
Demuxers are configured elements in FFmpeg that can read the
+multimedia streams from a particular type of file.
+
+
When you configure your FFmpeg build, all the supported demuxers
+are enabled by default. You can list all available ones using the
+configure option --list-demuxers.
+
+
You can disable all the demuxers using the configure option
+--disable-demuxers, and selectively enable a single demuxer with
+the option --enable-demuxer=DEMUXER, or disable it
+with the option --disable-demuxer=DEMUXER.
+
+
The option -formats of the ff* tools will display the list of
+enabled demuxers.
+
+
The description of some of the currently available demuxers follows.
+
This demuxer presents all AVStreams from all variant streams.
+The id field is set to the bitrate variant index number. By setting
+the discard flags on AVStreams (by pressing ’a’ or ’v’ in ffplay),
+the caller can decide which variant streams to actually receive.
+The total bitrate of the variant that the stream belongs to is
+available in a metadata key named "variant_bitrate".
+
This demuxer reads a list of files and other directives from a text file and
+demuxes them one after the other, as if all their packet had been muxed
+together.
+
+
The timestamps in the files are adjusted so that the first file starts at 0
+and each next file starts where the previous one finishes. Note that it is
+done globally and may cause gaps if all streams do not have exactly the same
+length.
+
+
All files must have the same streams (same codecs, same time base, etc.).
+
+
The duration of each file is used to adjust the timestamps of the next file:
+if the duration is incorrect (because it was computed using the bit-rate or
+because the file is truncated, for example), it can cause artifacts. The
+duration directive can be used to override the duration stored in
+each file.
+
The script is a text file in extended-ASCII, with one directive per line.
+Empty lines, leading spaces and lines starting with ’#’ are ignored. The
+following directive is recognized:
+
+
+
‘file path’
+
Path to a file to read; special characters and spaces must be escaped with
+backslash or single quotes.
+
+
All subsequent directives apply to that file.
+
+
+
‘ffconcat version 1.0’
+
Identify the script type and version. It also sets the ‘safe’ option
+to 1 if it was to its default -1.
+
+
To make FFmpeg recognize the format automatically, this directive must
+appears exactly as is (no extra space or byte-order-mark) on the very first
+line of the script.
+
+
+
‘duration dur’
+
Duration of the file. This information can be specified from the file;
+specifying it here may be more efficient or help if the information from the
+file is not available or accurate.
+
+
If the duration is set for all files, then it is possible to seek in the
+whole concatenated video.
+
If set to 1, reject unsafe file paths. A file path is considered safe if it
+does not contain a protocol specification and is relative and all components
+only contain characters from the portable character set (letters, digits,
+period, underscore and hyphen) and have no period at the beginning of a
+component.
+
+
If set to 0, any file name is accepted.
+
+
The default is -1, it is equivalent to 1 if the format was automatically
+probed and 0 otherwise.
+
Some files have multiple tracks. The demuxer will pick the first track by
+default. The ‘track_index’ option can be used to select a different
+track. Track indexes start at 0. The demuxer exports the number of tracks as
+tracks meta data entry.
+
+
For very large files, the ‘max_size’ option may have to be adjusted.
+
This demuxer reads from a list of image files specified by a pattern.
+The syntax and meaning of the pattern is specified by the
+option pattern_type.
+
+
The pattern may contain a suffix which is used to automatically
+determine the format of the images contained in the files.
+
+
The size, the pixel format, and the format of each image must be the
+same for all the files in the sequence.
+
+
This demuxer accepts the following options:
+
+
‘framerate’
+
Set the frame rate for the video stream. It defaults to 25.
+
+
‘loop’
+
If set to 1, loop over the input. Default value is 0.
+
+
‘pattern_type’
+
Select the pattern type used to interpret the provided filename.
+
+
pattern_type accepts one of the following values.
+
+
‘sequence’
+
Select a sequence pattern type, used to specify a sequence of files
+indexed by sequential numbers.
+
+
A sequence pattern may contain the string "%d" or "%0Nd", which
+specifies the position of the characters representing a sequential
+number in each filename matched by the pattern. If the form
+"%d0Nd" is used, the string representing the number in each
+filename is 0-padded and N is the total number of 0-padded
+digits representing the number. The literal character ’%’ can be
+specified in the pattern with the string "%%".
+
+
If the sequence pattern contains "%d" or "%0Nd", the first filename of
+the file list specified by the pattern must contain a number
+inclusively contained between start_number and
+start_number+start_number_range-1, and all the following
+numbers must be sequential.
+
+
For example the pattern "img-%03d.bmp" will match a sequence of
+filenames of the form ‘img-001.bmp’, ‘img-002.bmp’, ...,
+‘img-010.bmp’, etc.; the pattern "i%%m%%g-%d.jpg" will match a
+sequence of filenames of the form ‘i%m%g-1.jpg’,
+‘i%m%g-2.jpg’, ..., ‘i%m%g-10.jpg’, etc.
+
+
Note that the pattern must not necessarily contain "%d" or
+"%0Nd", for example to convert a single image file
+‘img.jpeg’ you can employ the command:
+
ffmpeg -i img.jpeg img.png
+
+
+
+
‘glob’
+
Select a glob wildcard pattern type.
+
+
The pattern is interpreted like a glob() pattern. This is only
+selectable if libavformat was compiled with globbing support.
+
+
+
‘glob_sequence (deprecated, will be removed)’
+
Select a mixed glob wildcard/sequence pattern.
+
+
If your version of libavformat was compiled with globbing support, and
+the provided pattern contains at least one glob meta character among
+%*?[]{} that is preceded by an unescaped "%", the pattern is
+interpreted like a glob() pattern, otherwise it is interpreted
+like a sequence pattern.
+
+
All glob special characters %*?[]{} must be prefixed
+with "%". To escape a literal "%" you shall use "%%".
+
+
For example the pattern foo-%*.jpeg will match all the
+filenames prefixed by "foo-" and terminating with ".jpeg", and
+foo-%?%?%?.jpeg will match all the filenames prefixed with
+"foo-", followed by a sequence of three characters, and terminating
+with ".jpeg".
+
+
This pattern type is deprecated in favor of glob and
+sequence.
+
+
+
+
Default value is glob_sequence.
+
+
‘pixel_format’
+
Set the pixel format of the images to read. If not specified the pixel
+format is guessed from the first image file in the sequence.
+
+
‘start_number’
+
Set the index of the file matched by the image file pattern to start
+to read from. Default value is 0.
+
+
‘start_number_range’
+
Set the index interval range to check when looking for the first image
+file in the sequence, starting from start_number. Default value
+is 5.
+
+
‘ts_from_file’
+
If set to 1, will set frame timestamp to modification time of image file. Note
+that monotonity of timestamps is not provided: images go in the same order as
+without this option. Default value is 0.
+
+
‘video_size’
+
Set the video size of the images to read. If not specified the video
+size is guessed from the first image file in the sequence.
+
+Use ffmpeg for creating a video from the images in the file
+sequence ‘img-001.jpeg’, ‘img-002.jpeg’, ..., assuming an
+input frame rate of 10 frames per second:
+
ffmpeg -framerate 10 -i 'img-%03d.jpeg' out.mkv
+
+
+
+As above, but start by reading from a file with index 100 in the sequence:
+
Overrides teletext packet PTS and DTS values with the timestamps calculated
+from the PCR of the first program which the teletext stream is part of and is
+not discarded. Default value is 1, set this option to 0 if you want your
+teletext packet PTS and DTS values untouched.
+
This demuxer allows to read raw video data. Since there is no header
+specifying the assumed video parameters, the user must specify them
+in order to be able to decode the data correctly.
+
+
This demuxer accepts the following options:
+
+
‘framerate’
+
Set input video frame rate. Default value is 25.
+
+
+
‘pixel_format’
+
Set the input video pixel format. Default value is yuv420p.
+
+
+
‘video_size’
+
Set the input video size. This value must be specified explicitly.
+
+
+
+
For example to read a rawvideo file ‘input.raw’ with
+ffplay, assuming a pixel format of rgb24, a video
+size of 320x240, and a frame rate of 10 images per second, use
+the command:
+
This demuxer reads the script language used by SBaGen
+http://uazu.net/sbagen/ to generate binaural beats sessions. A SBG
+script looks like that:
+
-SE
+a: 300-2.5/3 440+4.5/0
+b: 300-2.5/0 440+4.5/3
+off: -
+NOW == a
++0:07:00 == b
++0:14:00 == a
++0:21:00 == b
++0:30:00 off
+
+
+
A SBG script can mix absolute and relative timestamps. If the script uses
+either only absolute timestamps (including the script start time) or only
+relative ones, then its layout is fixed, and the conversion is
+straightforward. On the other hand, if the script mixes both kind of
+timestamps, then the NOW reference for relative timestamps will be
+taken from the current time of day at the time the script is read, and the
+script layout will be frozen according to that reference. That means that if
+the script is directly played, the actual times will match the absolute
+timestamps up to the sound controller’s clock accuracy, but if the user
+somehow pauses the playback or seeks, all times will be shifted accordingly.
+
TED does not provide links to the captions, but they can be guessed from the
+page. The file ‘tools/bookmarklets.html’ from the FFmpeg source tree
+contains a bookmarklet to expose them.
+
+
This demuxer accepts the following option:
+
+
‘start_time’
+
Set the start time of the TED talk, in milliseconds. The default is 15000
+(15s). It is used to sync the captions with the downloadable videos, because
+they include a 15s intro.
+
+
+
+
Example: convert the captions to a format most players understand:
+
Muxers are configured elements in FFmpeg which allow writing
+multimedia streams to a particular type of file.
+
+
When you configure your FFmpeg build, all the supported muxers
+are enabled by default. You can list all available muxers using the
+configure option --list-muxers.
+
+
You can disable all the muxers with the configure option
+--disable-muxers and selectively enable / disable single muxers
+with the options --enable-muxer=MUXER /
+--disable-muxer=MUXER.
+
+
The option -formats of the ff* tools will display the list of
+enabled muxers.
+
+
A description of some of the currently available muxers follows.
+
This muxer computes and prints the Adler-32 CRC of all the input audio
+and video frames. By default audio frames are converted to signed
+16-bit raw audio and video frames to raw video before computing the
+CRC.
+
+
The output of the muxer consists of a single line of the form:
+CRC=0xCRC, where CRC is a hexadecimal number 0-padded to
+8 digits containing the CRC for all the decoded input frames.
+
+
For example to compute the CRC of the input, and store it in the file
+‘out.crc’:
+
ffmpeg -i INPUT -f crc out.crc
+
+
+
You can print the CRC to stdout with the command:
+
ffmpeg -i INPUT -f crc -
+
+
+
You can select the output format of each frame with ffmpeg by
+specifying the audio and video codec and format. For example to
+compute the CRC of the input audio converted to PCM unsigned 8-bit
+and the input video converted to MPEG-2 video, use the command:
+
This muxer computes and prints the Adler-32 CRC for each audio
+and video packet. By default audio frames are converted to signed
+16-bit raw audio and video frames to raw video before computing the
+CRC.
+
+
The output of the muxer consists of a line for each audio and video
+packet of the form:
+
CRC is a hexadecimal number 0-padded to 8 digits containing the
+CRC of the packet.
+
+
For example to compute the CRC of the audio and video frames in
+‘INPUT’, converted to raw audio and video packets, and store it
+in the file ‘out.crc’:
+
ffmpeg -i INPUT -f framecrc out.crc
+
+
+
To print the information to stdout, use the command:
+
ffmpeg -i INPUT -f framecrc -
+
+
+
With ffmpeg, you can select the output format to which the
+audio and video frames are encoded before computing the CRC for each
+packet by specifying the audio and video codec. For example, to
+compute the CRC of each decoded input audio frame converted to PCM
+unsigned 8-bit and of each decoded input video frame converted to
+MPEG-2 video, use the command:
+
This muxer computes and prints the MD5 hash for each audio
+and video packet. By default audio frames are converted to signed
+16-bit raw audio and video frames to raw video before computing the
+hash.
+
+
The output of the muxer consists of a line for each audio and video
+packet of the form:
+
MD5 is a hexadecimal number representing the computed MD5 hash
+for the packet.
+
+
For example to compute the MD5 of the audio and video frames in
+‘INPUT’, converted to raw audio and video packets, and store it
+in the file ‘out.md5’:
+
ffmpeg -i INPUT -f framemd5 out.md5
+
+
+
To print the information to stdout, use the command:
+
Apple HTTP Live Streaming muxer that segments MPEG-TS according to
+the HTTP Live Streaming specification.
+
+
It creates a playlist file and numbered segment files. The output
+filename specifies the playlist filename; the segment filenames
+receive the same basename as the playlist, a sequential number and
+a .ts extension.
+
The image file muxer writes video frames to image files.
+
+
The output filenames are specified by a pattern, which can be used to
+produce sequentially numbered series of files.
+The pattern may contain the string "%d" or "%0Nd", this string
+specifies the position of the characters representing a numbering in
+the filenames. If the form "%0Nd" is used, the string
+representing the number in each filename is 0-padded to N
+digits. The literal character ’%’ can be specified in the pattern with
+the string "%%".
+
+
If the pattern contains "%d" or "%0Nd", the first filename of
+the file list specified will contain the number 1, all the following
+numbers will be sequential.
+
+
The pattern may contain a suffix which is used to automatically
+determine the format of the image files to write.
+
+
For example the pattern "img-%03d.bmp" will specify a sequence of
+filenames of the form ‘img-001.bmp’, ‘img-002.bmp’, ...,
+‘img-010.bmp’, etc.
+The pattern "img%%-%d.jpg" will specify a sequence of filenames of the
+form ‘img%-1.jpg’, ‘img%-2.jpg’, ..., ‘img%-10.jpg’,
+etc.
+
+
The following example shows how to use ffmpeg for creating a
+sequence of files ‘img-001.jpeg’, ‘img-002.jpeg’, ...,
+taking one image every second from the input video:
+
Note that with ffmpeg, if the format is not specified with the
+-f option and the output filename specifies an image file
+format, the image2 muxer is automatically selected, so the previous
+command can be written as:
+
ffmpeg -i in.avi -vsync 1 -r 1 'img-%03d.jpeg'
+
+
+
Note also that the pattern must not necessarily contain "%d" or
+"%0Nd", for example to create a single image file
+‘img.jpeg’ from the input video you can employ the command:
+
ffmpeg -i in.avi -f image2 -frames:v 1 img.jpeg
+
+
+
+
‘start_number number’
+
Start the sequence from number. Default value is 1. Must be a
+non-negative number.
+
+
+
‘-update number’
+
If number is nonzero, the filename will always be interpreted as just a
+filename, not a pattern, and this file will be continuously overwritten with new
+images.
+
+
+
+
+
The image muxer supports the .Y.U.V image file format. This format is
+special in that that each image frame consists of three files, for
+each of the YUV420P components. To read or write this image file format,
+specify the name of the ’.Y’ file. The muxer will automatically open the
+’.U’ and ’.V’ files as required.
+
By default, this muxer writes the index for seeking (called cues in Matroska
+terms) at the end of the file, because it cannot know in advance how much space
+to leave for the index at the beginning of the file. However for some use cases
+– e.g. streaming where seeking is possible but slow – it is useful to put the
+index at the beginning of the file.
+
+
If this option is set to a non-zero value, the muxer will reserve a given amount
+of space in the file header and then try to write the cues there when the muxing
+finishes. If the available space does not suffice, muxing will fail. A safe size
+for most use cases should be about 50kB per hour of video.
+
+
Note that cues are only written if the output is seekable and this option will
+have no effect if it is not.
+
This muxer computes and prints the MD5 hash of all the input audio
+and video frames. By default audio frames are converted to signed
+16-bit raw audio and video frames to raw video before computing the
+hash.
+
+
The output of the muxer consists of a single line of the form:
+MD5=MD5, where MD5 is a hexadecimal number representing
+the computed MD5 hash.
+
+
For example to compute the MD5 hash of the input converted to raw
+audio and video, and store it in the file ‘out.md5’:
+
ffmpeg -i INPUT -f md5 out.md5
+
+
+
You can print the MD5 to stdout with the command:
+
The mov/mp4/ismv muxer supports fragmentation. Normally, a MOV/MP4
+file has all the metadata about all packets stored in one location
+(written at the end of the file, it can be moved to the start for
+better playback by adding faststart to the movflags, or
+using the qt-faststart tool). A fragmented
+file consists of a number of fragments, where packets and metadata
+about these packets are stored together. Writing a fragmented
+file has the advantage that the file is decodable even if the
+writing is interrupted (while a normal MOV/MP4 is undecodable if
+it is not properly finished), and it requires less memory when writing
+very long files (since writing normal MOV/MP4 files stores info about
+every single packet in memory until the file is closed). The downside
+is that it is less compatible with other applications.
+
+
Fragmentation is enabled by setting one of the AVOptions that define
+how to cut the file into fragments:
+
+
+
‘-moov_size bytes’
+
Reserves space for the moov atom at the beginning of the file instead of placing the
+moov atom at the end. If the space reserved is insufficient, muxing will fail.
+
+
‘-movflags frag_keyframe’
+
Start a new fragment at each video keyframe.
+
+
‘-frag_duration duration’
+
Create fragments that are duration microseconds long.
+
+
‘-frag_size size’
+
Create fragments that contain up to size bytes of payload data.
+
+
‘-movflags frag_custom’
+
Allow the caller to manually choose when to cut fragments, by
+calling av_write_frame(ctx, NULL) to write a fragment with
+the packets written so far. (This is only useful with other
+applications integrating libavformat, not from ffmpeg.)
+
+
‘-min_frag_duration duration’
+
Don’t create fragments that are shorter than duration microseconds long.
+
+
+
+
If more than one condition is specified, fragments are cut when
+one of the specified conditions is fulfilled. The exception to this is
+-min_frag_duration, which has to be fulfilled for any of the other
+conditions to apply.
+
+
Additionally, the way the output file is written can be adjusted
+through a few other options:
+
+
+
‘-movflags empty_moov’
+
Write an initial moov atom directly at the start of the file, without
+describing any samples in it. Generally, an mdat/moov pair is written
+at the start of the file, as a normal MOV/MP4 file, containing only
+a short portion of the file. With this option set, there is no initial
+mdat atom, and the moov atom only describes the tracks but has
+a zero duration.
+
+
Files written with this option set do not work in QuickTime.
+This option is implicitly set when writing ismv (Smooth Streaming) files.
+
+
‘-movflags separate_moof’
+
Write a separate moof (movie fragment) atom for each track. Normally,
+packets for all tracks are written in a moof atom (which is slightly
+more efficient), but with this option set, the muxer writes one moof/mdat
+pair for each track, making it easier to separate tracks.
+
+
This option is implicitly set when writing ismv (Smooth Streaming) files.
+
+
‘-movflags faststart’
+
Run a second pass moving the index (moov atom) to the beginning of the file.
+This operation can take a while, and will not work in various situations such
+as fragmented output, thus it is not enabled by default.
+
+
‘-movflags rtphint’
+
Add RTP hinting tracks to the output file.
+
+
+
+
Smooth Streaming content can be pushed in real time to a publishing
+point on IIS with this muxer. Example:
+
The MP3 muxer writes a raw MP3 stream with an ID3v2 header at the beginning and
+optionally an ID3v1 tag at the end. ID3v2.3 and ID3v2.4 are supported, the
+id3v2_version option controls which one is used. The legacy ID3v1 tag is
+not written by default, but may be enabled with the write_id3v1 option.
+
+
For seekable output the muxer also writes a Xing frame at the beginning, which
+contains the number of frames in the file. It is useful for computing duration
+of VBR files.
+
+
The muxer supports writing ID3v2 attached pictures (APIC frames). The pictures
+are supplied to the muxer in form of a video stream with a single packet. There
+can be any number of those streams, each will correspond to a single APIC frame.
+The stream metadata tags title and comment map to APIC
+description and picture type respectively. See
+http://id3.org/id3v2.4.0-frames for allowed picture types.
+
+
Note that the APIC frames must be written at the beginning, so the muxer will
+buffer the audio frames until it gets all the pictures. It is therefore advised
+to provide the pictures as soon as possible to avoid excessive buffering.
+
+
Examples:
+
+
Write an mp3 with an ID3v2.3 header and an ID3v1 footer:
+
This muxer implements ISO 13818-1 and part of ETSI EN 300 468.
+
+
The muxer options are:
+
+
+
‘-mpegts_original_network_id number’
+
Set the original_network_id (default 0x0001). This is unique identifier
+of a network in DVB. Its main use is in the unique identification of a
+service through the path Original_Network_ID, Transport_Stream_ID.
+
+
‘-mpegts_transport_stream_id number’
+
Set the transport_stream_id (default 0x0001). This identifies a
+transponder in DVB.
+
+
‘-mpegts_service_id number’
+
Set the service_id (default 0x0001) also known as program in DVB.
+
+
‘-mpegts_pmt_start_pid number’
+
Set the first PID for PMT (default 0x1000, max 0x1f00).
+
+
‘-mpegts_start_pid number’
+
Set the first PID for data packets (default 0x0100, max 0x0f00).
+
+
‘-mpegts_m2ts_mode number’
+
Enable m2ts mode if set to 1. Default value is -1 which disables m2ts mode.
+
+
‘-muxrate number’
+
Set muxrate.
+
+
‘-pes_payload_size number’
+
Set minimum PES packet payload in bytes.
+
+
‘-mpegts_flags flags’
+
Set flags (see below).
+
+
‘-mpegts_copyts number’
+
Preserve original timestamps, if value is set to 1. Default value is -1, which
+results in shifting timestamps so that they start from 0.
+
+
‘-tables_version number’
+
Set PAT, PMT and SDT version (default 0, valid values are from 0 to 31, inclusively).
+This option allows updating stream structure so that standard consumer may
+detect the change. To do so, reopen output AVFormatContext (in case of API
+usage) or restart ffmpeg instance, cyclically changing tables_version value:
+
Option mpegts_flags may take a set of such flags:
+
+
+
‘resend_headers’
+
Reemit PAT/PMT before writing the next packet.
+
+
‘latm’
+
Use LATM packetization for AAC.
+
+
+
+
The recognized metadata settings in mpegts muxer are service_provider
+and service_name. If they are not set the default for
+service_provider is "FFmpeg" and the default for
+service_name is "Service01".
+
Preferred page duration, in microseconds. The muxer will attempt to create
+pages that are approximately duration microseconds long. This allows the
+user to compromise between seek granularity and container overhead. The default
+is 1 second. A value of 0 will fill all segments, making pages as large as
+possible. A value of 1 will effectively use 1 packet-per-page in most
+situations, giving a small seek granularity at the cost of additional container
+overhead.
+
The segmenter muxer outputs streams to a number of separate files of nearly
+fixed duration. Output filename pattern can be set in a fashion similar to
+image2.
+
+
stream_segment is a variant of the muxer used to write to
+streaming output formats, i.e. which do not require global headers,
+and is recommended for outputting e.g. to MPEG transport stream segments.
+ssegment is a shorter alias for stream_segment.
+
+
Every segment starts with a keyframe of the selected reference stream,
+which is set through the ‘reference_stream’ option.
+
+
Note that if you want accurate splitting for a video file, you need to
+make the input key frames correspond to the exact splitting times
+expected by the segmenter, or the segment muxer will start the new
+segment with the key frame found next after the specified start
+time.
+
+
The segment muxer works best with a single constant frame rate video.
+
+
Optionally it can generate a list of the created segments, by setting
+the option segment_list. The list type is specified by the
+segment_list_type option.
+
+
The segment muxer supports the following options:
+
+
+
‘reference_stream specifier’
+
Set the reference stream, as specified by the string specifier.
+If specifier is set to auto, the reference is choosen
+automatically. Otherwise it must be a stream specifier (see the “Stream
+specifiers” chapter in the ffmpeg manual) which specifies the
+reference stream. The default value is auto.
+
+
+
‘segment_format format’
+
Override the inner container format, by default it is guessed by the filename
+extension.
+
+
+
‘segment_list name’
+
Generate also a listfile named name. If not specified no
+listfile is generated.
+
+
+
‘segment_list_flags flags’
+
Set flags affecting the segment list generation.
+
+
It currently supports the following flags:
+
+
‘cache’
+
Allow caching (only affects M3U8 list files).
+
+
+
‘live’
+
Allow live-friendly file generation.
+
+
+
+
Default value is samp.
+
+
+
‘segment_list_size size’
+
Update the list file so that it contains at most the last size
+segments. If 0 the list file will contain all the segments. Default
+value is 0.
+
+
+
‘segment_list_type type’
+
Specify the format for the segment list file.
+
+
The following values are recognized:
+
+
‘flat’
+
Generate a flat list for the created segments, one segment per line.
+
+
+
‘csv, ext’
+
Generate a list for the created segments, one segment per line,
+each line matching the format (comma-separated values):
+
segment_filename is the name of the output file generated by the
+muxer according to the provided pattern. CSV escaping (according to
+RFC4180) is applied if required.
+
+
segment_start_time and segment_end_time specify
+the segment start and end time expressed in seconds.
+
+
A list file with the suffix ".csv" or ".ext" will
+auto-select this format.
+
+
‘ext’ is deprecated in favor or ‘csv’.
+
+
+
‘ffconcat’
+
Generate an ffconcat file for the created segments. The resulting file
+can be read using the FFmpeg concat demuxer.
+
+
A list file with the suffix ".ffcat" or ".ffconcat" will
+auto-select this format.
+
A list file with the suffix ".m3u8" will auto-select this format.
+
+
+
+
If not specified the type is guessed from the list file name suffix.
+
+
+
‘segment_time time’
+
Set segment duration to time, the value must be a duration
+specification. Default value is "2". See also the
+‘segment_times’ option.
+
+
Note that splitting may not be accurate, unless you force the
+reference stream key-frames at the given time. See the introductory
+notice and the examples below.
+
+
+
‘segment_time_delta delta’
+
Specify the accuracy time when selecting the start time for a
+segment, expressed as a duration specification. Default value is "0".
+
+
When delta is specified a key-frame will start a new segment if its
+PTS satisfies the relation:
+
PTS >= start_time - time_delta
+
+
+
This option is useful when splitting video content, which is always
+split at GOP boundaries, in case a key frame is found just before the
+specified split time.
+
+
In particular may be used in combination with the ‘ffmpeg’ option
+force_key_frames. The key frame times specified by
+force_key_frames may not be set accurately because of rounding
+issues, with the consequence that a key frame time may result set just
+before the specified time. For constant frame rate videos a value of
+1/2*frame_rate should address the worst case mismatch between
+the specified time and the time set by force_key_frames.
+
+
+
‘segment_times times’
+
Specify a list of split points. times contains a list of comma
+separated duration specifications, in increasing order. See also
+the ‘segment_time’ option.
+
+
+
‘segment_frames frames’
+
Specify a list of split video frame numbers. frames contains a
+list of comma separated integer numbers, in increasing order.
+
+
This option specifies to start a new segment whenever a reference
+stream key frame is found and the sequential number (starting from 0)
+of the frame is greater or equal to the next value in the list.
+
+
+
‘segment_wrap limit’
+
Wrap around segment index once it reaches limit.
+
+
+
‘segment_start_number number’
+
Set the sequence number of the first segment. Defaults to 0.
+
+
+
‘reset_timestamps 1|0’
+
Reset timestamps at the begin of each segment, so that each segment
+will start with near-zero timestamps. It is meant to ease the playback
+of the generated segments. May not work with some combinations of
+muxers/codecs. It is set to 0 by default.
+
+
+
‘initial_offset offset’
+
Specify timestamp offset to apply to the output packet timestamps. The
+argument must be a time duration specification, and defaults to 0.
+
+To remux the content of file ‘in.mkv’ to a list of segments
+‘out-000.nut’, ‘out-001.nut’, etc., and write the list of
+generated segments to ‘out.list’:
+
+As the example above, but use the ffmpeg ‘force_key_frames’
+option to force key frames in the input at the specified location, together
+with the segment option ‘segment_time_delta’ to account for
+possible roundings operated when setting key frame times.
+
The tee muxer can be used to write the same data to several files or any
+other kind of muxer. It can be used, for example, to both stream a video to
+the network and save it to disk at the same time.
+
+
It is different from specifying several outputs to the ffmpeg
+command-line tool because the audio and video data will be encoded only once
+with the tee muxer; encoding can be a very expensive process. It is not
+useful when using the libavformat API directly because it is then possible
+to feed the same packets to several muxers directly.
+
+
The slave outputs are specified in the file name given to the muxer,
+separated by ’|’. If any of the slave name contains the ’|’ separator,
+leading or trailing spaces or any special character, it must be
+escaped (see the “Quoting and escaping” section in the ffmpeg-utils
+manual).
+
+
Muxer options can be specified for each slave by prepending them as a list of
+key=value pairs separated by ’:’, between square brackets. If
+the options values contain a special character or the ’:’ separator, they
+must be escaped; note that this is a second level escaping.
+
+
The following special options are also recognized:
+
+
‘f’
+
Specify the format name. Useful if it cannot be guessed from the
+output name suffix.
+
+
+
‘bsfs[/spec]’
+
Specify a list of bitstream filters to apply to the specified
+output. It is possible to specify to which streams a given bitstream
+filter applies, by appending a stream specifier to the option
+separated by /. If the stream specifier is not specified, the
+bistream filters will be applied to all streams in the output.
+
+
Several bitstream filters can be specified, separated by ",".
+
+
+
‘select’
+
Select the streams that should be mapped to the slave output,
+specified by a stream specifier. If not specified, this defaults to
+all the input streams.
+
+
+
+
Some examples follow.
+
+
+Encode something and both archive it in a WebM file and stream it
+as MPEG-TS over UDP (the streams need to be explicitly mapped):
+
+Use ffmpeg to encode the input, and send the output
+to three different destinations. The dump_extra bitstream
+filter is used to add extradata information to all the output video
+keyframes packets, as requested by the MPEG-TS format. The select
+option is applied to ‘out.aac’ in order to make it contain only
+audio packets.
+
Note: some codecs may need different options depending on the output format;
+the auto-detection of this can not work with the tee muxer. The main example
+is the ‘global_header’ flag.
+
FFmpeg is able to dump metadata from media files into a simple UTF-8-encoded
+INI-like text file and then load it back using the metadata muxer/demuxer.
+
+
The file format is as follows:
+
+
+A file consists of a header and a number of metadata tags divided into sections,
+each on its own line.
+
+
+The header is a ’;FFMETADATA’ string, followed by a version number (now 1).
+
+
+Metadata tags are of the form ’key=value’
+
+
+Immediately after header follows global metadata
+
+
+After global metadata there may be sections with per-stream/per-chapter
+metadata.
+
+
+A section starts with the section name in uppercase (i.e. STREAM or CHAPTER) in
+brackets (’[’, ’]’) and ends with next section or end of file.
+
+
+At the beginning of a chapter section there may be an optional timebase to be
+used for start/end values. It must be in form ’TIMEBASE=num/den’, where num and
+den are integers. If the timebase is missing then start/end times are assumed to
+be in milliseconds.
+Next a chapter section must contain chapter start and end times in form
+’START=num’, ’END=num’, where num is a positive integer.
+
+
+Empty lines and lines starting with ’;’ or ’#’ are ignored.
+
+
+Metadata keys or values containing special characters (’=’, ’;’, ’#’, ’\’ and a
+newline) must be escaped with a backslash ’\’.
+
+
+Note that whitespace in metadata (e.g. foo = bar) is considered to be a part of
+the tag (in the example above key is ’foo ’, value is ’ bar’).
+
+
+
A ffmetadata file might look like this:
+
;FFMETADATA1
+title=bike\\shed
+;this is a comment
+artist=FFmpeg troll team
+
+[CHAPTER]
+TIMEBASE=1/1000
+START=0
+#chapter ends at 0:01:00
+END=60000
+title=chapter \#1
+[STREAM]
+title=multi\
+line
+
+
+
By using the ffmetadata muxer and demuxer it is possible to extract
+metadata from an input file to an ffmetadata file, and then transcode
+the file into an output file with the edited ffmetadata file.
+
+
Extracting an ffmetadata file with ‘ffmpeg’ goes as follows:
+
ffmpeg -i INPUT -f ffmetadata FFMETADATAFILE
+
+
+
Reinserting edited metadata information from the FFMETADATAFILE file can
+be done as:
+
Protocols are configured elements in FFmpeg that enable access to
+resources that require specific protocols.
+
+
When you configure your FFmpeg build, all the supported protocols are
+enabled by default. You can list all available ones using the
+configure option "–list-protocols".
+
+
You can disable all the protocols using the configure option
+"–disable-protocols", and selectively enable a protocol using the
+option "–enable-protocol=PROTOCOL", or you can disable a
+particular protocol using the option
+"–disable-protocol=PROTOCOL".
+
+
The option "-protocols" of the ff* tools will display the list of
+supported protocols.
+
+
A description of the currently available protocols follows.
+
For example to read from a file ‘input.mpeg’ with ffmpeg
+use the command:
+
ffmpeg -i file:input.mpeg output.mpeg
+
+
+
The ff* tools default to the file protocol, that is a resource
+specified with the name "FILE.mpeg" is interpreted as the URL
+"file:FILE.mpeg".
+
+
This protocol accepts the following options:
+
+
+
‘truncate’
+
Truncate existing files on write, if set to 1. A value of 0 prevents
+truncating. Default value is 1.
+
+
+
‘blocksize’
+
Set I/O operation maximum block size, in bytes. Default value is
+INT_MAX, which results in not limiting the requested block size.
+Setting this value reasonably low improves user termination request reaction
+time, which is valuable for files on slow medium.
+
Set timeout of socket I/O operations used by the underlying low level
+operation. By default it is set to -1, which means that the timeout is
+not specified.
+
+
+
‘ftp-anonymous-password’
+
Password used when login as anonymous user. Typically an e-mail address
+should be used.
+
+
+
‘ftp-write-seekable’
+
Control seekability of connection during encoding. If set to 1 the
+resource is supposed to be seekable, if set to 0 it is assumed not
+to be seekable. Default value is 0.
+
+
+
+
NOTE: Protocol can be used as output, but it is recommended to not do
+it, unless special care is taken (tests, customized server configuration
+etc.). Different FTP servers behave in different way during seek
+operation. ff* tools may produce incomplete content due to server limitations.
+
Read Apple HTTP Live Streaming compliant segmented stream as
+a uniform one. The M3U8 playlists describing the segments can be
+remote HTTP resources or local files, accessed using the standard
+file protocol.
+The nested protocol is declared by specifying
+"+proto" after the hls URI scheme name, where proto
+is either "file" or "http".
+
Using this protocol is discouraged - the hls demuxer should work
+just as well (if not, please report the issues) and is more complete.
+To use the hls demuxer instead, simply use the direct URLs to the
+m3u8 files.
+
Control seekability of connection. If set to 1 the resource is
+supposed to be seekable, if set to 0 it is assumed not to be seekable,
+if set to -1 it will try to autodetect if it is seekable. Default
+value is -1.
+
+
+
‘chunked_post’
+
If set to 1 use chunked transfer-encoding for posts, default is 1.
+
+
+
‘headers’
+
Set custom HTTP headers, can override built in default headers. The
+value must be a string encoding the headers.
+
+
+
‘content_type’
+
Force a content type.
+
+
+
‘user-agent’
+
Override User-Agent header. If not specified the protocol will use a
+string describing the libavformat build.
+
+
+
‘multiple_requests’
+
Use persistent connections if set to 1. By default it is 0.
+
+
+
‘post_data’
+
Set custom HTTP post data.
+
+
+
‘timeout’
+
Set timeout of socket I/O operations used by the underlying low level
+operation. By default it is set to -1, which means that the timeout is
+not specified.
+
+
+
‘mime_type’
+
Set MIME type.
+
+
+
‘icy’
+
If set to 1 request ICY (SHOUTcast) metadata from the server. If the server
+supports this, the metadata has to be retrieved by the application by reading
+the ‘icy_metadata_headers’ and ‘icy_metadata_packet’ options.
+The default is 0.
+
+
+
‘icy_metadata_headers’
+
If the server supports ICY metadata, this contains the ICY specific HTTP reply
+headers, separated with newline characters.
+
+
+
‘icy_metadata_packet’
+
If the server supports ICY metadata, and ‘icy’ was set to 1, this
+contains the last non-empty metadata packet sent by the server.
+
+
+
‘cookies’
+
Set the cookies to be sent in future requests. The format of each cookie is the
+same as the value of a Set-Cookie HTTP response field. Multiple cookies can be
+delimited by a newline character.
+
Some HTTP requests will be denied unless cookie values are passed in with the
+request. The ‘cookies’ option allows these cookies to be specified. At
+the very least, each cookie must specify a value along with a path and domain.
+HTTP requests that match both the domain and path will automatically include the
+cookie value in the HTTP Cookie header field. Multiple cookies can be delimited
+by a newline.
+
+
The required syntax to play a stream specifying a cookie is:
+
Computes the MD5 hash of the data to be written, and on close writes
+this to the designated output or stdout if none is specified. It can
+be used to test muxers without writing an actual file.
+
+
Some examples follow.
+
# Write the MD5 hash of the encoded AVI file to the file output.avi.md5.
+ffmpeg -i input.flv -f avi -y md5:output.avi.md5
+
+# Write the MD5 hash of the encoded AVI file to stdout.
+ffmpeg -i input.flv -f avi -y md5:
+
+
+
Note that some formats (typically MOV) require the output protocol to
+be seekable, so they will fail with the MD5 output protocol.
+
number is the number corresponding to the file descriptor of the
+pipe (e.g. 0 for stdin, 1 for stdout, 2 for stderr). If number
+is not specified, by default the stdout file descriptor will be used
+for writing, stdin for reading.
+
+
For example to read from stdin with ffmpeg:
+
cat test.wav | ffmpeg -i pipe:0
+# ...this is the same as...
+cat test.wav | ffmpeg -i pipe:
+
+
+
For writing to stdout with ffmpeg:
+
ffmpeg -i test.wav -f avi pipe:1 | cat > test.avi
+# ...this is the same as...
+ffmpeg -i test.wav -f avi pipe: | cat > test.avi
+
+
+
This protocol accepts the following options:
+
+
+
‘blocksize’
+
Set I/O operation maximum block size, in bytes. Default value is
+INT_MAX, which results in not limiting the requested block size.
+Setting this value reasonably low improves user termination request reaction
+time, which is valuable if data transmission is slow.
+
+
+
+
Note that some formats (typically MOV), require the output protocol to
+be seekable, so they will fail with the pipe output protocol.
+
The number of the TCP port to use (by default is 1935).
+
+
+
‘app’
+
It is the name of the application to access. It usually corresponds to
+the path where the application is installed on the RTMP server
+(e.g. ‘/ondemand/’, ‘/flash/live/’, etc.). You can override
+the value parsed from the URI through the rtmp_app option, too.
+
+
+
‘playpath’
+
It is the path or name of the resource to play with reference to the
+application specified in app, may be prefixed by "mp4:". You
+can override the value parsed from the URI through the rtmp_playpath
+option, too.
+
+
+
‘listen’
+
Act as a server, listening for an incoming connection.
+
+
+
‘timeout’
+
Maximum time to wait for the incoming connection. Implies listen.
+
+
+
+
Additionally, the following parameters can be set via command line options
+(or in code via AVOptions):
+
+
‘rtmp_app’
+
Name of application to connect on the RTMP server. This option
+overrides the parameter specified in the URI.
+
+
+
‘rtmp_buffer’
+
Set the client buffer time in milliseconds. The default is 3000.
+
+
+
‘rtmp_conn’
+
Extra arbitrary AMF connection parameters, parsed from a string,
+e.g. like B:1 S:authMe O:1 NN:code:1.23 NS:flag:ok O:0.
+Each value is prefixed by a single character denoting the type,
+B for Boolean, N for number, S for string, O for object, or Z for null,
+followed by a colon. For Booleans the data must be either 0 or 1 for
+FALSE or TRUE, respectively. Likewise for Objects the data must be 0 or
+1 to end or begin an object, respectively. Data items in subobjects may
+be named, by prefixing the type with ’N’ and specifying the name before
+the value (i.e. NB:myFlag:1). This option may be used multiple
+times to construct arbitrary AMF sequences.
+
+
+
‘rtmp_flashver’
+
Version of the Flash plugin used to run the SWF player. The default
+is LNX 9,0,124,2. (When publishing, the default is FMLE/3.0 (compatible;
+<libavformat version>).)
+
+
+
‘rtmp_flush_interval’
+
Number of packets flushed in the same request (RTMPT only). The default
+is 10.
+
+
+
‘rtmp_live’
+
Specify that the media is a live stream. No resuming or seeking in
+live streams is possible. The default value is any, which means the
+subscriber first tries to play the live stream specified in the
+playpath. If a live stream of that name is not found, it plays the
+recorded stream. The other possible values are live and
+recorded.
+
+
+
‘rtmp_pageurl’
+
URL of the web page in which the media was embedded. By default no
+value will be sent.
+
+
+
‘rtmp_playpath’
+
Stream identifier to play or to publish. This option overrides the
+parameter specified in the URI.
+
+
+
‘rtmp_subscribe’
+
Name of live stream to subscribe to. By default no value will be sent.
+It is only sent if the option is specified or if rtmp_live
+is set to live.
+
+
+
‘rtmp_swfhash’
+
SHA256 hash of the decompressed SWF file (32 bytes).
+
+
+
‘rtmp_swfsize’
+
Size of the decompressed SWF file, required for SWFVerification.
+
+
+
‘rtmp_swfurl’
+
URL of the SWF player for the media. By default no value will be sent.
+
+
+
‘rtmp_swfverify’
+
URL to player swf file, compute hash/size automatically.
+
+
+
‘rtmp_tcurl’
+
URL of the target stream. Defaults to proto://host[:port]/app.
+
+
+
+
+
For example to read with ffplay a multimedia resource named
+"sample" from the application "vod" from an RTMP server "myserver":
+
ffplay rtmp://myserver/vod/sample
+
+
+
To publish to a password protected server, passing the playpath and
+app names separately:
+
The Encrypted Real-Time Messaging Protocol (RTMPE) is used for
+streaming multimedia content within standard cryptographic primitives,
+consisting of Diffie-Hellman key exchange and HMACSHA256, generating
+a pair of RC4 keys.
+
Real-Time Messaging Protocol tunneled through HTTP.
+
+
The Real-Time Messaging Protocol tunneled through HTTP (RTMPT) is used
+for streaming multimedia content within HTTP requests to traverse
+firewalls.
+
Encrypted Real-Time Messaging Protocol tunneled through HTTP.
+
+
The Encrypted Real-Time Messaging Protocol tunneled through HTTP (RTMPTE)
+is used for streaming multimedia content within HTTP requests to traverse
+firewalls.
+
Real-Time Messaging Protocol tunneled through HTTPS.
+
+
The Real-Time Messaging Protocol tunneled through HTTPS (RTMPTS) is used
+for streaming multimedia content within HTTPS requests to traverse
+firewalls.
+
Set timeout of socket I/O operations used by the underlying low level
+operation. By default it is set to -1, which means that the timeout
+is not specified.
+
+
+
‘truncate’
+
Truncate existing files on write, if set to 1. A value of 0 prevents
+truncating. Default value is 1.
+
Real-Time Messaging Protocol and its variants supported through
+librtmp.
+
+
Requires the presence of the librtmp headers and library during
+configuration. You need to explicitly configure the build with
+"–enable-librtmp". If enabled this will replace the native RTMP
+protocol.
+
+
This protocol provides most client functions and a few server
+functions needed to support RTMP, RTMP tunneled in HTTP (RTMPT),
+encrypted RTMP (RTMPE), RTMP over SSL/TLS (RTMPS) and tunneled
+variants of these encrypted types (RTMPTE, RTMPTS).
+
where rtmp_proto is one of the strings "rtmp", "rtmpt", "rtmpe",
+"rtmps", "rtmpte", "rtmpts" corresponding to each RTMP variant, and
+server, port, app and playpath have the same
+meaning as specified for the RTMP native protocol.
+options contains a list of space-separated options of the form
+key=val.
+
+
See the librtmp manual page (man 3 librtmp) for more information.
+
+
For example, to stream a file in real-time to an RTMP server using
+ffmpeg:
+
RTSP is not technically a protocol handler in libavformat, it is a demuxer
+and muxer. The demuxer supports both normal RTSP (with data transferred
+over RTP; this is used by e.g. Apple and Microsoft) and Real-RTSP (with
+data transferred over RDT).
+
+
The muxer can be used to send a stream using RTSP ANNOUNCE to a server
+supporting it (currently Darwin Streaming Server and Mischa Spiegelmock’s
+RTSP server).
+
+
The required syntax for a RTSP url is:
+
rtsp://hostname[:port]/path
+
+
+
The following options (set on the ffmpeg/ffplay command
+line, or set in code via AVOptions or in avformat_open_input),
+are supported:
+
+
Flags for rtsp_transport:
+
+
+
‘udp’
+
Use UDP as lower transport protocol.
+
+
+
‘tcp’
+
Use TCP (interleaving within the RTSP control channel) as lower
+transport protocol.
+
+
+
‘udp_multicast’
+
Use UDP multicast as lower transport protocol.
+
+
+
‘http’
+
Use HTTP tunneling as lower transport protocol, which is useful for
+passing proxies.
+
+
+
+
Multiple lower transport protocols may be specified, in that case they are
+tried one at a time (if the setup of one fails, the next one is tried).
+For the muxer, only the tcp and udp options are supported.
+
+
Flags for rtsp_flags:
+
+
+
‘filter_src’
+
Accept packets only from negotiated peer address and port.
+
+
‘listen’
+
Act as a server, listening for an incoming connection.
+
+
+
+
When receiving data over UDP, the demuxer tries to reorder received packets
+(since they may arrive out of order, or packets may get lost totally). This
+can be disabled by setting the maximum demuxing delay to zero (via
+the max_delay field of AVFormatContext).
+
+
When watching multi-bitrate Real-RTSP streams with ffplay, the
+streams to display can be chosen with -vstn and
+-astn for video and audio respectively, and can be switched
+on the fly by pressing v and a.
+
+
Example command lines:
+
+
To watch a stream over UDP, with a max reordering delay of 0.5 seconds:
+
Session Announcement Protocol (RFC 2974). This is not technically a
+protocol handler in libavformat, it is a muxer and demuxer.
+It is used for signalling of RTP streams, by announcing the SDP for the
+streams regularly on a separate port.
+
The RTP packets are sent to destination on port port,
+or to port 5004 if no port is specified.
+options is a &-separated list. The following options
+are supported:
+
+
+
‘announce_addr=address’
+
Specify the destination IP address for sending the announcements to.
+If omitted, the announcements are sent to the commonly used SAP
+announcement multicast address 224.2.127.254 (sap.mcast.net), or
+ff0e::2:7ffe if destination is an IPv6 address.
+
+
+
‘announce_port=port’
+
Specify the port to send the announcements on, defaults to
+9875 if not specified.
+
+
+
‘ttl=ttl’
+
Specify the time to live value for the announcements and RTP packets,
+defaults to 255.
+
+
+
‘same_port=0|1’
+
If set to 1, send all RTP streams on the same port pair. If zero (the
+default), all streams are sent on unique ports, with each stream on a
+port 2 numbers higher than the previous.
+VLC/Live555 requires this to be set to 1, to be able to receive the stream.
+The RTP stack in libavformat for receiving requires all streams to be sent
+on unique ports.
+
+
+
+
Example command lines follow.
+
+
To broadcast a stream on the local subnet, for watching in VLC:
+
+
ffmpeg -re -i input -f sap sap://224.0.0.255?same_port=1
+
+
+
Similarly, for watching in ffplay:
+
+
ffmpeg -re -i input -f sap sap://224.0.0.255
+
+
+
And for watching in ffplay, over IPv6:
+
+
ffmpeg -re -i input -f sap sap://[ff0e::1:2:3:4]
+
The syntax for a SAP url given to the demuxer is:
+
sap://[address][:port]
+
+
+
address is the multicast address to listen for announcements on,
+if omitted, the default 224.2.127.254 (sap.mcast.net) is used. port
+is the port that is listened on, 9875 if omitted.
+
+
The demuxers listens for announcements on the given address and port.
+Once an announcement is received, it tries to receive that particular stream.
+
+
Example command lines follow.
+
+
To play back the first stream announced on the normal SAP multicast address:
+
+
ffplay sap://
+
+
+
To play back the first stream announced on one the default IPv6 SAP multicast address:
+
Set input and output encoding parameters, which are expressed by a
+base64-encoded representation of a binary block. The first 16 bytes of
+this binary block are used as master key, the following 14 bytes are
+used as master salt.
+
In read mode: if no data arrived in more than this time interval, raise error.
+In write mode: if socket cannot be written in more than this time interval, raise error.
+This also sets timeout on TCP connection establishing.
+
+
ffmpeg -i input -f format tcp://hostname:port?listen
+ffplay tcp://hostname:port
+
Transport Layer Security (TLS) / Secure Sockets Layer (SSL)
+
+
The required syntax for a TLS/SSL url is:
+
tls://hostname:port[?options]
+
+
+
The following parameters can be set via command line options
+(or in code via AVOptions):
+
+
+
‘ca_file, cafile=filename’
+
A file containing certificate authority (CA) root certificates to treat
+as trusted. If the linked TLS library contains a default this might not
+need to be specified for verification to work, but not all libraries and
+setups have defaults built in.
+The file must be in OpenSSL PEM format.
+
+
+
‘tls_verify=1|0’
+
If enabled, try to verify the peer that we are communicating with.
+Note, if using OpenSSL, this currently only makes sure that the
+peer certificate is signed by one of the root certificates in the CA
+database, but it does not validate that the certificate actually
+matches the host name we are trying to connect to. (With GnuTLS,
+the host name is validated as well.)
+
+
This is disabled by default since it requires a CA database to be
+provided by the caller in many cases.
+
+
+
‘cert_file, cert=filename’
+
A file containing a certificate to use in the handshake with the peer.
+(When operating as server, in listen mode, this is more often required
+by the peer, while client certificates only are mandated in certain
+setups.)
+
+
+
‘key_file, key=filename’
+
A file containing the private key for the certificate.
+
+
+
‘listen=1|0’
+
If enabled, listen for connections on the provided port, and assume
+the server role in the handshake instead of the client role.
+
+
+
+
+
Example command lines:
+
+
To create a TLS/SSL server that serves an input stream.
+
+
ffmpeg -i input -f format tls://hostname:port?listen&cert=server.crt&key=server.key
+
+
+
To play back a stream from the TLS/SSL server using ffplay:
+
options contains a list of &-separated options of the form key=val.
+
+
In case threading is enabled on the system, a circular buffer is used
+to store the incoming data, which allows to reduce loss of data due to
+UDP socket buffer overruns. The fifo_size and
+overrun_nonfatal options are related to this buffer.
+
+
The list of supported options follows.
+
+
+
‘buffer_size=size’
+
Set the UDP socket buffer size in bytes. This is used both for the
+receiving and the sending buffer size.
+
+
+
‘localport=port’
+
Override the local UDP port to bind with.
+
+
+
‘localaddr=addr’
+
Choose the local IP address. This is useful e.g. if sending multicast
+and the host has multiple interfaces, where the user can choose
+which interface to send on by specifying the IP address of that interface.
+
+
+
‘pkt_size=size’
+
Set the size in bytes of UDP packets.
+
+
+
‘reuse=1|0’
+
Explicitly allow or disallow reusing UDP sockets.
+
+
+
‘ttl=ttl’
+
Set the time to live value (for multicast only).
+
+
+
‘connect=1|0’
+
Initialize the UDP socket with connect(). In this case, the
+destination address can’t be changed with ff_udp_set_remote_url later.
+If the destination address isn’t known at the start, this option can
+be specified in ff_udp_set_remote_url, too.
+This allows finding out the source address for the packets with getsockname,
+and makes writes return with AVERROR(ECONNREFUSED) if "destination
+unreachable" is received.
+For receiving, this gives the benefit of only receiving packets from
+the specified peer address/port.
+
+
+
‘sources=address[,address]’
+
Only receive packets sent to the multicast group from one of the
+specified sender IP addresses.
+
+
+
‘block=address[,address]’
+
Ignore packets sent to the multicast group from the specified
+sender IP addresses.
+
+
+
‘fifo_size=units’
+
Set the UDP receiving circular buffer size, expressed as a number of
+packets with size of 188 bytes. If not specified defaults to 7*4096.
+
+
+
‘overrun_nonfatal=1|0’
+
Survive in case of UDP receiving circular buffer overrun. Default
+value is 0.
+
+
+
‘timeout=microseconds’
+
In read mode: if no data arrived in more than this time interval, raise error.
+
+
+
+
Some usage examples of the UDP protocol with ffmpeg follow.
+
+
To stream over UDP to a remote endpoint:
+
ffmpeg -i input -f format udp://hostname:port
+
+
+
To stream in mpegts format over UDP using 188 sized UDP packets, using a large input buffer:
+
The libavdevice library provides the same interface as
+libavformat. Namely, an input device is considered like a demuxer, and
+an output device like a muxer, and the interface and generic device
+options are the same provided by libavformat (see the ffmpeg-formats
+manual).
+
+
In addition each input or output device may support so-called private
+options, which are specific for that component.
+
+
Options may be set by specifying -optionvalue in the
+FFmpeg tools, or by setting the value explicitly in the device
+AVFormatContext options or using the ‘libavutil/opt.h’ API
+for programmatic use.
+
Input devices are configured elements in FFmpeg which allow to access
+the data coming from a multimedia device attached to your system.
+
+
When you configure your FFmpeg build, all the supported input devices
+are enabled by default. You can list all available ones using the
+configure option "–list-indevs".
+
+
You can disable all the input devices using the configure option
+"–disable-indevs", and selectively enable an input device using the
+option "–enable-indev=INDEV", or you can disable a particular
+input device using the option "–disable-indev=INDEV".
+
+
The option "-formats" of the ff* tools will display the list of
+supported input devices (amongst the demuxers).
+
+
A description of the currently available input devices follows.
+
If no options are specified, the device’s defaults are used.
+If the device does not support the requested options, it will
+fail to open.
+
+
+
‘video_size’
+
Set the video size in the captured video.
+
+
+
‘framerate’
+
Set the frame rate in the captured video.
+
+
+
‘sample_rate’
+
Set the sample rate (in Hz) of the captured audio.
+
+
+
‘sample_size’
+
Set the sample size (in bits) of the captured audio.
+
+
+
‘channels’
+
Set the number of channels in the captured audio.
+
+
+
‘list_devices’
+
If set to ‘true’, print a list of devices and exit.
+
+
+
‘list_options’
+
If set to ‘true’, print a list of selected device’s options
+and exit.
+
+
+
‘video_device_number’
+
Set video device number for devices with same name (starts at 0,
+defaults to 0).
+
+
+
‘audio_device_number’
+
Set audio device number for devices with same name (starts at 0,
+defaults to 0).
+
+
+
‘pixel_format’
+
Select pixel format to be used by DirectShow. This may only be set when
+the video codec is not set or set to rawvideo.
+
+
+
‘audio_buffer_size’
+
Set audio device buffer size in milliseconds (which can directly
+impact latency, depending on the device).
+Defaults to using the audio device’s
+default buffer size (typically some multiple of 500ms).
+Setting this value too low can degrade performance.
+See also
+http://msdn.microsoft.com/en-us/library/windows/desktop/dd377582(v=vs.85).aspx
+
The Linux framebuffer is a graphic hardware-independent abstraction
+layer to show graphics on a computer monitor, typically on the
+console. It is accessed through a file device node, usually
+‘/dev/fb0’.
+
+
For more detailed information read the file
+Documentation/fb/framebuffer.txt included in the Linux source tree.
+
+
To record from the framebuffer device ‘/dev/fb0’ with
+ffmpeg:
+
ffmpeg -f fbdev -r 10 -i /dev/fb0 out.avi
+
+
+
You can take a single screenshot image with the command:
+
To enable this input device, you need libiec61883, libraw1394 and
+libavc1394 installed on your system. Use the configure option
+--enable-libiec61883 to compile with the device enabled.
+
+
The iec61883 capture device supports capturing from a video device
+connected via IEEE1394 (FireWire), using libiec61883 and the new Linux
+FireWire stack (juju). This is the default DV/HDV input method in Linux
+Kernel 2.6.37 and later, since the old FireWire stack was removed.
+
+
Specify the FireWire port to be used as input file, or "auto"
+to choose the first port connected.
+
Override autodetection of DV/HDV. This should only be used if auto
+detection does not work, or if usage of a different device type
+should be prohibited. Treating a DV device as HDV (or vice versa) will
+not work and result in undefined behavior.
+The values ‘auto’, ‘dv’ and ‘hdv’ are supported.
+
+
+
‘dvbuffer’
+
Set maxiumum size of buffer for incoming data, in frames. For DV, this
+is an exact value. For HDV, it is not frame exact, since HDV does
+not have a fixed frame size.
+
+
+
‘dvguid’
+
Select the capture device by specifying it’s GUID. Capturing will only
+be performed from the specified device and fails if no device with the
+given GUID is found. This is useful to select the input if multiple
+devices are connected at the same time.
+Look at /sys/bus/firewire/devices to find out the GUIDs.
+
To enable this input device during configuration you need libjack
+installed on your system.
+
+
A JACK input device creates one or more JACK writable clients, one for
+each audio channel, with name client_name:input_N, where
+client_name is the name provided by the application, and N
+is a number which identifies the channel.
+Each writable client will send the acquired data to the FFmpeg input
+device.
+
+
Once you have created one or more JACK readable clients, you need to
+connect them to one or more JACK writable clients.
+
+
To connect or disconnect JACK clients you can use the jack_connect
+and jack_disconnect programs, or do it through a graphical interface,
+for example with qjackctl.
+
+
To list the JACK clients and their properties you can invoke the command
+jack_lsp.
+
+
Follows an example which shows how to capture a JACK readable client
+with ffmpeg.
+
# Create a JACK writable client with name "ffmpeg".
+$ ffmpeg -f jack -i ffmpeg -y out.wav
+
+# Start the sample jack_metro readable client.
+$ jack_metro -b 120 -d 0.2 -f 4000
+
+# List the current JACK clients.
+$ jack_lsp -c
+system:capture_1
+system:capture_2
+system:playback_1
+system:playback_2
+ffmpeg:input_1
+metro:120_bpm
+
+# Connect metro to the ffmpeg writable client.
+$ jack_connect metro:120_bpm ffmpeg:input_1
+
This input device reads data from the open output pads of a libavfilter
+filtergraph.
+
+
For each filtergraph open output, the input device will create a
+corresponding stream which is mapped to the generated output. Currently
+only video data is supported. The filtergraph is specified through the
+option ‘graph’.
+
Specify the filtergraph to use as input. Each video open output must be
+labelled by a unique string of the form "outN", where N is a
+number starting from 0 corresponding to the mapped input stream
+generated by the device.
+The first unlabelled output is automatically assigned to the "out0"
+label, but all the others need to be specified explicitly.
+
+
If not specified defaults to the filename specified for the input
+device.
+
+
+
‘graph_file’
+
Set the filename of the filtergraph to be read and sent to the other
+filters. Syntax of the filtergraph is the same as the one specified by
+the option graph.
+
The OpenAL input device provides audio capture on all systems with a
+working OpenAL 1.1 implementation.
+
+
To enable this input device during configuration, you need OpenAL
+headers and libraries installed on your system, and need to configure
+FFmpeg with --enable-openal.
+
+
OpenAL headers and libraries should be provided as part of your OpenAL
+implementation, or as an additional download (an SDK). Depending on your
+installation you may need to specify additional flags via the
+--extra-cflags and --extra-ldflags for allowing the build
+system to locate the OpenAL headers and libraries.
+
+
An incomplete list of OpenAL implementations follows:
+
+
+
Creative
+
The official Windows implementation, providing hardware acceleration
+with supported devices and software fallback.
+See http://openal.org/.
+
+
OpenAL Soft
+
Portable, open source (LGPL) software implementation. Includes
+backends for the most common sound APIs on the Windows, Linux,
+Solaris, and BSD operating systems.
+See http://kcat.strangesoft.net/openal.html.
+
This device allows to capture from an audio input device handled
+through OpenAL.
+
+
You need to specify the name of the device to capture in the provided
+filename. If the empty string is provided, the device will
+automatically select the default device. You can get the list of the
+supported devices by using the option list_devices.
+
If FFmpeg is built with v4l-utils support (by using the
+--enable-libv4l2 configure option), it is possible to use it with the
+-use_libv4l2 input device option.
+
+
The name of the device to grab is a file device node, usually Linux
+systems tend to automatically create such nodes when the device
+(e.g. an USB webcam) is plugged into the system, and has a name of the
+kind ‘/dev/videoN’, where N is a number associated to
+the device.
+
+
Video4Linux2 devices usually support a limited set of
+widthxheight sizes and frame rates. You can check which are
+supported using -list_formats all for Video4Linux2 devices.
+Some devices, like TV cards, support one or more standards. It is possible
+to list all the supported standards using -list_standards all.
+
+
The time base for the timestamps is 1 microsecond. Depending on the kernel
+version and configuration, the timestamps may be derived from the real time
+clock (origin at the Unix Epoch) or the monotonic clock (origin usually at
+boot time, unaffected by NTP or manual changes to the clock). The
+‘-timestamps abs’ or ‘-ts abs’ option can be used to force
+conversion into the real time clock.
+
+
Some usage examples of the video4linux2 device with ffmpeg
+and ffplay:
+
+
+Grab and show the input of a video4linux2 device:
+
The filename passed as input is the capture driver number, ranging from
+0 to 9. You may use "list" as filename to print a list of drivers. Any
+other filename will be interpreted as device number 0.
+
hostname:display_number.screen_number specifies the
+X11 display name of the screen to grab from. hostname can be
+omitted, and defaults to "localhost". The environment variable
+DISPLAY contains the default display name.
+
+
x_offset and y_offset specify the offsets of the grabbed
+area with respect to the top-left border of the X11 screen. They
+default to 0.
+
+
Check the X11 documentation (e.g. man X) for more detailed information.
+
+
Use the dpyinfo program for getting basic information about the
+properties of your X11 display (e.g. grep for "name" or "dimensions").
+
Specify whether to draw the mouse pointer. A value of 0 specify
+not to draw the pointer. Default value is 1.
+
+
+
‘follow_mouse’
+
Make the grabbed area follow the mouse. The argument can be
+centered or a number of pixels PIXELS.
+
+
When it is specified with "centered", the grabbing region follows the mouse
+pointer and keeps the pointer at the center of region; otherwise, the region
+follows only when the mouse pointer reaches within PIXELS (greater than
+zero) to the edge of region.
+
Set the grabbing frame rate. Default value is ntsc,
+corresponding to a frame rate of 30000/1001.
+
+
+
‘show_region’
+
Show grabbed region on screen.
+
+
If show_region is specified with 1, then the grabbing
+region will be indicated on screen. With this option, it is easy to
+know what is being grabbed if only a portion of the screen is grabbed.
+
Output devices are configured elements in FFmpeg that can write
+multimedia data to an output device attached to your system.
+
+
When you configure your FFmpeg build, all the supported output devices
+are enabled by default. You can list all available ones using the
+configure option "–list-outdevs".
+
+
You can disable all the output devices using the configure option
+"–disable-outdevs", and selectively enable an output device using the
+option "–enable-outdev=OUTDEV", or you can disable a particular
+input device using the option "–disable-outdev=OUTDEV".
+
+
The option "-formats" of the ff* tools will display the list of
+enabled output devices (amongst the muxers).
+
+
A description of the currently available output devices follows.
+
This output device allows to show a video stream in CACA window.
+Only one CACA window is allowed per application, so you can
+have only one instance of this output device in an application.
+
+
To enable this output device you need to configure FFmpeg with
+--enable-libcaca.
+libcaca is a graphics library that outputs text instead of pixels.
+
Set the CACA window title, if not specified default to the filename
+specified for the output device.
+
+
+
‘window_size’
+
Set the CACA window size, can be a string of the form
+widthxheight or a video size abbreviation.
+If not specified it defaults to the size of the input video.
+
+
+
‘driver’
+
Set display driver.
+
+
+
‘algorithm’
+
Set dithering algorithm. Dithering is necessary
+because the picture being rendered has usually far more colours than
+the available palette.
+The accepted values are listed with -list_dither algorithms.
+
+
+
‘antialias’
+
Set antialias method. Antialiasing smoothens the rendered
+image and avoids the commonly seen staircase effect.
+The accepted values are listed with -list_dither antialiases.
+
+
+
‘charset’
+
Set which characters are going to be used when rendering text.
+The accepted values are listed with -list_dither charsets.
+
+
+
‘color’
+
Set color to be used when rendering text.
+The accepted values are listed with -list_dither colors.
+
+
+
‘list_drivers’
+
If set to ‘true’, print a list of available drivers and exit.
+
+
+
‘list_dither’
+
List available dither options related to the argument.
+The argument must be one of algorithms, antialiases,
+charsets, colors.
+
The Linux framebuffer is a graphic hardware-independent abstraction
+layer to show graphics on a computer monitor, typically on the
+console. It is accessed through a file device node, usually
+‘/dev/fb0’.
+
+
For more detailed information read the file
+‘Documentation/fb/framebuffer.txt’ included in the Linux source tree.
+
This output device allows to show a video stream in an SDL
+window. Only one SDL window is allowed per application, so you can
+have only one instance of this output device in an application.
+
+
To enable this output device you need libsdl installed on your system
+when configuring your build.
+
Set the SDL window title, if not specified default to the filename
+specified for the output device.
+
+
+
‘icon_title’
+
Set the name of the iconified SDL window, if not specified it is set
+to the same value of window_title.
+
+
+
‘window_size’
+
Set the SDL window size, can be a string of the form
+widthxheight or a video size abbreviation.
+If not specified it defaults to the size of the input video,
+downscaled according to the aspect ratio.
+
+
+
‘window_fullscreen’
+
Set fullscreen mode when non-zero value is provided.
+Zero is a default.
+
Specify the hardware display name, which determines the display and
+communications domain to be used.
+
+
The display name or DISPLAY environment variable can be a string in
+the format hostname[:number[.screen_number]].
+
+
hostname specifies the name of the host machine on which the
+display is physically attached. number specifies the number of
+the display server on that host machine. screen_number specifies
+the screen to be used on that server.
+
+
If unspecified, it defaults to the value of the DISPLAY environment
+variable.
+
+
For example, dual-headed:0.1 would specify screen 1 of display
+0 on the machine named “dual-headed”.
+
+
Check the X11 specification for more detailed information about the
+display name format.
+
+
+
‘window_size’
+
Set the created window size, can be a string of the form
+widthxheight or a video size abbreviation. If not
+specified it defaults to the size of the input video.
+
+
+
‘window_x’
+
‘window_y’
+
Set the X and Y window offsets for the created window. They are both
+set to 0 by default. The values may be ignored by the window manager.
+
+
+
‘window_title’
+
Set the window title, if not specified default to the filename
+specified for the output device.
+
The audio resampler supports the following named options.
+
+
Options may be set by specifying -optionvalue in the
+FFmpeg tools, option=value for the aresample filter,
+by setting the value explicitly in the
+SwrContext options or using the ‘libavutil/opt.h’ API for
+programmatic use.
+
+
+
‘ich, in_channel_count’
+
Set the number of input channels. Default value is 0. Setting this
+value is not mandatory if the corresponding channel layout
+‘in_channel_layout’ is set.
+
+
+
‘och, out_channel_count’
+
Set the number of output channels. Default value is 0. Setting this
+value is not mandatory if the corresponding channel layout
+‘out_channel_layout’ is set.
+
+
+
‘uch, used_channel_count’
+
Set the number of used input channels. Default value is 0. This option is
+only used for special remapping.
+
+
+
‘isr, in_sample_rate’
+
Set the input sample rate. Default value is 0.
+
+
+
‘osr, out_sample_rate’
+
Set the output sample rate. Default value is 0.
+
+
+
‘isf, in_sample_fmt’
+
Specify the input sample format. It is set by default to none.
+
+
+
‘osf, out_sample_fmt’
+
Specify the output sample format. It is set by default to none.
+
+
+
‘tsf, internal_sample_fmt’
+
Set the internal sample format. Default value is none.
+This will automatically be chosen when it is not explicitly set.
+
Set the center mix level. It is a value expressed in deciBel, and must be
+in the interval [-32,32].
+
+
+
‘slev, surround_mix_level’
+
Set the surround mix level. It is a value expressed in deciBel, and must
+be in the interval [-32,32].
+
+
+
‘lfe_mix_level’
+
Set LFE mix into non LFE level. It is used when there is a LFE input but no
+LFE output. It is a value expressed in deciBel, and must
+be in the interval [-32,32].
+
+
+
‘rmvol, rematrix_volume’
+
Set rematrix volume. Default value is 1.0.
+
+
+
‘rematrix_maxval’
+
Set maximum output value for rematrixing.
+This can be used to prevent clipping vs. preventing volumn reduction
+A value of 1.0 prevents cliping.
+
+
+
‘flags, swr_flags’
+
Set flags used by the converter. Default value is 0.
+
+
It supports the following individual flags:
+
+
‘res’
+
force resampling, this flag forces resampling to be used even when the
+input and output sample rates match.
+
+
+
+
+
‘dither_scale’
+
Set the dither scale. Default value is 1.
+
+
+
‘dither_method’
+
Set dither method. Default value is 0.
+
+
Supported values:
+
+
‘rectangular’
+
select rectangular dither
+
+
‘triangular’
+
select triangular dither
+
+
‘triangular_hp’
+
select triangular dither with high pass
+
+
‘lipshitz’
+
select lipshitz noise shaping dither
+
+
‘shibata’
+
select shibata noise shaping dither
+
+
‘low_shibata’
+
select low shibata noise shaping dither
+
+
‘high_shibata’
+
select high shibata noise shaping dither
+
+
‘f_weighted’
+
select f-weighted noise shaping dither
+
+
‘modified_e_weighted’
+
select modified-e-weighted noise shaping dither
+
+
‘improved_e_weighted’
+
select improved-e-weighted noise shaping dither
+
+
+
+
+
+
‘resampler’
+
Set resampling engine. Default value is swr.
+
+
Supported values:
+
+
‘swr’
+
select the native SW Resampler; filter options precision and cheby are not
+applicable in this case.
+
+
‘soxr’
+
select the SoX Resampler (where available); compensation, and filter options
+filter_size, phase_shift, filter_type & kaiser_beta, are not applicable in this
+case.
+
+
+
+
+
‘filter_size’
+
For swr only, set resampling filter size, default value is 32.
+
+
+
‘phase_shift’
+
For swr only, set resampling phase shift, default value is 10, and must be in
+the interval [0,30].
+
+
+
‘linear_interp’
+
Use Linear Interpolation if set to 1, default value is 0.
+
+
+
‘cutoff’
+
Set cutoff frequency (swr: 6dB point; soxr: 0dB point) ratio; must be a float
+value between 0 and 1. Default value is 0.97 with swr, and 0.91 with soxr
+(which, with a sample-rate of 44100, preserves the entire audio band to 20kHz).
+
+
+
‘precision’
+
For soxr only, the precision in bits to which the resampled signal will be
+calculated. The default value of 20 (which, with suitable dithering, is
+appropriate for a destination bit-depth of 16) gives SoX’s ’High Quality’; a
+value of 28 gives SoX’s ’Very High Quality’.
+
+
+
‘cheby’
+
For soxr only, selects passband rolloff none (Chebyshev) & higher-precision
+approximation for ’irrational’ ratios. Default value is 0.
+
+
+
‘async’
+
For swr only, simple 1 parameter audio sync to timestamps using stretching,
+squeezing, filling and trimming. Setting this to 1 will enable filling and
+trimming, larger values represent the maximum amount in samples that the data
+may be stretched or squeezed for each second.
+Default value is 0, thus no compensation is applied to make the samples match
+the audio timestamps.
+
+
+
‘first_pts’
+
For swr only, assume the first pts should be this value. The time unit is 1 / sample rate.
+This allows for padding/trimming at the start of stream. By default, no
+assumption is made about the first frame’s expected pts, so no padding or
+trimming is done. For example, this could be set to 0 to pad the beginning with
+silence if an audio stream starts after the video stream or to trim any samples
+with a negative pts due to encoder delay.
+
+
+
‘min_comp’
+
For swr only, set the minimum difference between timestamps and audio data (in
+seconds) to trigger stretching/squeezing/filling or trimming of the
+data to make it match the timestamps. The default is that
+stretching/squeezing/filling and trimming is disabled
+(‘min_comp’ = FLT_MAX).
+
+
+
‘min_hard_comp’
+
For swr only, set the minimum difference between timestamps and audio data (in
+seconds) to trigger adding/dropping samples to make it match the
+timestamps. This option effectively is a threshold to select between
+hard (trim/fill) and soft (squeeze/stretch) compensation. Note that
+all compensation is by default disabled through ‘min_comp’.
+The default is 0.1.
+
+
+
‘comp_duration’
+
For swr only, set duration (in seconds) over which data is stretched/squeezed
+to make it match the timestamps. Must be a non-negative double float value,
+default value is 1.0.
+
+
+
‘max_soft_comp’
+
For swr only, set maximum factor by which data is stretched/squeezed to make it
+match the timestamps. Must be a non-negative double float value, default value
+is 0.
+
+
+
‘matrix_encoding’
+
Select matrixed stereo encoding.
+
+
It accepts the following values:
+
+
‘none’
+
select none
+
+
‘dolby’
+
select Dolby
+
+
‘dplii’
+
select Dolby Pro Logic II
+
+
+
+
Default value is none.
+
+
+
‘filter_type’
+
For swr only, select resampling filter type. This only affects resampling
+operations.
+
+
It accepts the following values:
+
+
‘cubic’
+
select cubic
+
+
‘blackman_nuttall’
+
select Blackman Nuttall Windowed Sinc
+
+
‘kaiser’
+
select Kaiser Windowed Sinc
+
+
+
+
+
‘kaiser_beta’
+
For swr only, set Kaiser Window Beta value. Must be an integer in the
+interval [2,16], default value is 9.
+
+
+
‘output_sample_bits’
+
For swr only, set number of used output sample bits for dithering. Must be an integer in the
+interval [0,64], default value is 0, which means it’s not used.
+
The video scaler supports the following named options.
+
+
Options may be set by specifying -optionvalue in the
+FFmpeg tools. For programmatic use, they can be set explicitly in the
+SwsContext options or through the ‘libavutil/opt.h’ API.
+
+
+
+
+
+
‘sws_flags’
+
Set the scaler flags. This is also used to set the scaling
+algorithm. Only a single algorithm should be selected.
+
+
It accepts the following values:
+
+
‘fast_bilinear’
+
Select fast bilinear scaling algorithm.
+
+
+
‘bilinear’
+
Select bilinear scaling algorithm.
+
+
+
‘bicubic’
+
Select bicubic scaling algorithm.
+
+
+
‘experimental’
+
Select experimental scaling algorithm.
+
+
+
‘neighbor’
+
Select nearest neighbor rescaling algorithm.
+
+
+
‘area’
+
Select averaging area rescaling algorithm.
+
+
+
‘bicubiclin’
+
Select bicubic scaling algorithm for the luma component, bilinear for
+chroma components.
+
Set source pixel format (must be expressed as an integer).
+
+
+
‘dst_format’
+
Set destination pixel format (must be expressed as an integer).
+
+
+
‘src_range’
+
Select source range.
+
+
+
‘dst_range’
+
Select destination range.
+
+
+
‘param0, param1’
+
Set scaling algorithm parameters. The specified values are specific of
+some scaling algorithms and ignored by others. The specified values
+are floating point number values.
+
+
+
‘sws_dither’
+
Set the dithering algorithm. Accepts one of the following
+values. Default value is ‘auto’.
+
Filtering in FFmpeg is enabled through the libavfilter library.
+
+
In libavfilter, a filter can have multiple inputs and multiple
+outputs.
+To illustrate the sorts of things that are possible, we consider the
+following filtergraph.
+
This filtergraph splits the input stream in two streams, sends one
+stream through the crop filter and the vflip filter before merging it
+back with the other stream by overlaying it on top. You can use the
+following command to achieve this:
+
The result will be that in output the top half of the video is mirrored
+onto the bottom half.
+
+
Filters in the same linear chain are separated by commas, and distinct
+linear chains of filters are separated by semicolons. In our example,
+crop,vflip are in one linear chain, split and
+overlay are separately in another. The points where the linear
+chains join are labelled by names enclosed in square brackets. In the
+example, the split filter generates two outputs that are associated to
+the labels [main] and [tmp].
+
+
The stream sent to the second output of split, labelled as
+[tmp], is processed through the crop filter, which crops
+away the lower half part of the video, and then vertically flipped. The
+overlay filter takes in input the first unchanged output of the
+split filter (which was labelled as [main]), and overlay on its
+lower half the output generated by the crop,vflip filterchain.
+
+
Some filters take in input a list of parameters: they are specified
+after the filter name and an equal sign, and are separated from each other
+by a colon.
+
+
There exist so-called source filters that do not have an
+audio/video input, and sink filters that will not have audio/video
+output.
+
The ‘graph2dot’ program included in the FFmpeg ‘tools’
+directory can be used to parse a filtergraph description and issue a
+corresponding textual representation in the dot language.
+
+
Invoke the command:
+
graph2dot -h
+
+
+
to see how to use ‘graph2dot’.
+
+
You can then pass the dot description to the ‘dot’ program (from
+the graphviz suite of programs) and obtain a graphical representation
+of the filtergraph.
+
can be used to create and display an image representing the graph
+described by the GRAPH_DESCRIPTION string. Note that this string must be
+a complete self-contained graph, with its inputs and outputs explicitly defined.
+For example if your command line is of the form:
+
ffmpeg -i infile -vf scale=640:360 outfile
+
+
your GRAPH_DESCRIPTION string will need to be of the form:
+
nullsrc,scale=640:360,nullsink
+
+
you may also need to set the nullsrc parameters and add a format
+filter in order to simulate a specific input file.
+
A filtergraph is a directed graph of connected filters. It can contain
+cycles, and there can be multiple links between a pair of
+filters. Each link has one input pad on one side connecting it to one
+filter from which it takes its input, and one output pad on the other
+side connecting it to the one filter accepting its output.
+
+
Each filter in a filtergraph is an instance of a filter class
+registered in the application, which defines the features and the
+number of input and output pads of the filter.
+
+
A filter with no input pads is called a "source", a filter with no
+output pads is called a "sink".
+
A filtergraph can be represented using a textual representation, which is
+recognized by the ‘-filter’/‘-vf’ and ‘-filter_complex’
+options in ffmpeg and ‘-vf’ in ffplay, and by the
+avfilter_graph_parse()/avfilter_graph_parse2() function defined in
+‘libavfilter/avfilter.h’.
+
+
A filterchain consists of a sequence of connected filters, each one
+connected to the previous one in the sequence. A filterchain is
+represented by a list of ","-separated filter descriptions.
+
+
A filtergraph consists of a sequence of filterchains. A sequence of
+filterchains is represented by a list of ";"-separated filterchain
+descriptions.
+
+
A filter is represented by a string of the form:
+[in_link_1]...[in_link_N]filter_name=arguments[out_link_1]...[out_link_M]
+
+
filter_name is the name of the filter class of which the
+described filter is an instance of, and has to be the name of one of
+the filter classes registered in the program.
+The name of the filter class is optionally followed by a string
+"=arguments".
+
+
arguments is a string which contains the parameters used to
+initialize the filter instance. It may have one of the following forms:
+
+
+A ’:’-separated list of key=value pairs.
+
+
+A ’:’-separated list of value. In this case, the keys are assumed to be
+the option names in the order they are declared. E.g. the fade filter
+declares three options in this order – ‘type’, ‘start_frame’ and
+‘nb_frames’. Then the parameter list in:0:30 means that the value
+in is assigned to the option ‘type’, 0 to
+‘start_frame’ and 30 to ‘nb_frames’.
+
+
+A ’:’-separated list of mixed direct value and long key=value
+pairs. The direct value must precede the key=value pairs, and
+follow the same constraints order of the previous point. The following
+key=value pairs can be set in any preferred order.
+
+
+
+
If the option value itself is a list of items (e.g. the format filter
+takes a list of pixel formats), the items in the list are usually separated by
+’|’.
+
+
The list of arguments can be quoted using the character "’" as initial
+and ending mark, and the character ’\’ for escaping the characters
+within the quoted text; otherwise the argument string is considered
+terminated when the next special character (belonging to the set
+"[]=;,") is encountered.
+
+
The name and arguments of the filter are optionally preceded and
+followed by a list of link labels.
+A link label allows to name a link and associate it to a filter output
+or input pad. The preceding labels in_link_1
+... in_link_N, are associated to the filter input pads,
+the following labels out_link_1 ... out_link_M, are
+associated to the output pads.
+
+
When two link labels with the same name are found in the
+filtergraph, a link between the corresponding input and output pad is
+created.
+
+
If an output pad is not labelled, it is linked by default to the first
+unlabelled input pad of the next filter in the filterchain.
+For example in the filterchain:
+
nullsrc, split[L1], [L2]overlay, nullsink
+
+
the split filter instance has two output pads, and the overlay filter
+instance two input pads. The first output pad of split is labelled
+"L1", the first input pad of overlay is labelled "L2", and the second
+output pad of split is linked to the second input pad of overlay,
+which are both unlabelled.
+
+
In a complete filterchain all the unlabelled filter input and output
+pads must be connected. A filtergraph is considered valid if all the
+filter input and output pads of all the filterchains are connected.
+
+
Libavfilter will automatically insert scale filters where format
+conversion is required. It is possible to specify swscale flags
+for those automatically inserted scalers by prepending
+sws_flags=flags;
+to the filtergraph description.
+
+
Follows a BNF description for the filtergraph syntax:
+
NAME ::= sequence of alphanumeric characters and '_'
+LINKLABEL ::= "[" NAME "]"
+LINKLABELS ::= LINKLABEL [LINKLABELS]
+FILTER_ARGUMENTS ::= sequence of chars (eventually quoted)
+FILTER ::= [LINKLABELS] NAME ["=" FILTER_ARGUMENTS] [LINKLABELS]
+FILTERCHAIN ::= FILTER [,FILTERCHAIN]
+FILTERGRAPH ::= [sws_flags=flags;] FILTERCHAIN [;FILTERGRAPH]
+
Some filter arguments require the use of special characters, typically
+: to separate key=value pairs in a named options list. In this
+case the user should perform a first level escaping when specifying
+the filter arguments. For example, consider the following literal
+string to be embedded in the drawtext filter arguments:
+
this is a 'string': may contain one, or more, special characters
+
+
+
Since : is special for the filter arguments syntax, it needs to
+be escaped, so you get:
+
text=this is a \'string\'\: may contain one, or more, special characters
+
+
+
A second level of escaping is required when embedding the filter
+arguments in a filtergraph description, in order to escape all the
+filtergraph special characters. Thus the example above becomes:
+
drawtext=text=this is a \\\'string\\\'\\: may contain one\, or more\, special characters
+
+
+
Finally an additional level of escaping may be needed when writing the
+filtergraph description in a shell command, which depends on the
+escaping rules of the adopted shell. For example, assuming that
+\ is special and needs to be escaped with another \, the
+previous string will finally result in:
+
-vf "drawtext=text=this is a \\\\\\'string\\\\\\'\\\\: may contain one\\, or more\\, special characters"
+
+
+
Sometimes, it might be more convenient to employ quoting in place of
+escaping. For example the string:
+
Caesar: tu quoque, Brute, fili mi
+
+
+
Can be quoted in the filter arguments as:
+
text='Caesar: tu quoque, Brute, fili mi'
+
+
+
And finally inserted in a filtergraph like:
+
drawtext=text=\'Caesar: tu quoque\, Brute\, fili mi\'
+
+
+
See the “Quoting and escaping” section in the ffmpeg-utils manual
+for more information about the escaping and quoting rules adopted by
+FFmpeg.
+
Some filters support a generic ‘enable’ option. For the filters
+supporting timeline editing, this option can be set to an expression which is
+evaluated before sending a frame to the filter. If the evaluation is non-zero,
+the filter will be enabled, otherwise the frame will be sent unchanged to the
+next filter in the filtergraph.
+
+
The expression accepts the following values:
+
+
‘t’
+
timestamp expressed in seconds, NAN if the input timestamp is unknown
+
+
+
‘n’
+
sequential number of the input frame, starting from 0
+
+
+
‘pos’
+
the position in the file of the input frame, NAN if unknown
+
+
+
+
Additionally, these filters support an ‘enable’ command that can be used
+to re-define the expression.
+
+
Like any other filtering option, the ‘enable’ option follows the same
+rules.
+
+
For example, to enable a blur filter (smartblur) from 10 seconds to 3
+minutes, and a curves filter starting at 3 seconds:
+
When you configure your FFmpeg build, you can disable any of the
+existing filters using --disable-filters.
+The configure output will show the audio filters included in your
+build.
+
+
Below is a description of the currently available audio filters.
+
The filter accepts a string of the form:
+"sample_format:channel_layout".
+
+
sample_format specifies the sample format, and can be a string or the
+corresponding numeric value defined in ‘libavutil/samplefmt.h’. Use ’p’
+suffix for a planar sample format.
+
+
channel_layout specifies the channel layout, and can be a string
+or the corresponding number value defined in ‘libavutil/channel_layout.h’.
+
+
The special parameter "auto", signifies that the filter will
+automatically select the output format depending on the output filter.
+
Samples in delayed channel are filled with silence.
+
+
The filter accepts the following option:
+
+
+
‘delays’
+
Set list of delays in milliseconds for each channel separated by ’|’.
+At least one delay greater than 0 should be provided.
+Unused delays will be silently ignored. If number of given delays is
+smaller than number of channels all remaining channels will not be delayed.
+
+Delay first channel by 1.5 seconds, the third channel by 0.5 seconds and leave
+the second channel (and any other channels that may be present) unchanged.
+
Echoes are reflected sound and can occur naturally amongst mountains
+(and sometimes large buildings) when talking or shouting; digital echo
+effects emulate this behaviour and are often used to help fill out the
+sound of a single instrument or vocal. The time difference between the
+original signal and the reflection is the delay, and the
+loudness of the reflected signal is the decay.
+Multiple echoes can have different delays and decays.
+
+
A description of the accepted parameters follows.
+
+
+
‘in_gain’
+
Set input gain of reflected signal. Default is 0.6.
+
+
+
‘out_gain’
+
Set output gain of reflected signal. Default is 0.3.
+
+
+
‘delays’
+
Set list of time intervals in milliseconds between original signal and reflections
+separated by ’|’. Allowed range for each delay is (0 - 90000.0].
+Default is 1000.
+
+
+
‘decays’
+
Set list of loudnesses of reflected signals separated by ’|’.
+Allowed range for each decay is (0 - 1.0].
+Default is 0.5.
+
A description of the accepted parameters follows.
+
+
+
‘type, t’
+
Specify the effect type, can be either in for fade-in, or
+out for a fade-out effect. Default is in.
+
+
+
‘start_sample, ss’
+
Specify the number of the start sample for starting to apply the fade
+effect. Default is 0.
+
+
+
‘nb_samples, ns’
+
Specify the number of samples for which the fade effect has to last. At
+the end of the fade-in effect the output audio will have the same
+volume as the input audio, at the end of the fade-out transition
+the output audio will be silence. Default is 44100.
+
+
+
‘start_time, st’
+
Specify time for starting to apply the fade effect. Default is 0.
+The accepted syntax is:
+
[-]HH[:MM[:SS[.m...]]]
+[-]S+[.m...]
+
+
See also the function av_parse_time().
+If set this option is used instead of start_sample one.
+
+
+
‘duration, d’
+
Specify the duration for which the fade effect has to last. Default is 0.
+The accepted syntax is:
+
[-]HH[:MM[:SS[.m...]]]
+[-]S+[.m...]
+
+
See also the function av_parse_time().
+At the end of the fade-in effect the output audio will have the same
+volume as the input audio, at the end of the fade-out transition
+the output audio will be silence.
+If set this option is used instead of nb_samples one.
+
Apply a two-pole all-pass filter with central frequency (in Hz)
+frequency, and filter-width width.
+An all-pass filter changes the audio’s frequency to phase relationship
+without changing its frequency to amplitude relationship.
+
+
The filter accepts the following options:
+
+
+
‘frequency, f’
+
Set frequency in Hz.
+
+
+
‘width_type’
+
Set method to specify band-width of filter.
+
+
‘h’
+
Hz
+
+
‘q’
+
Q-Factor
+
+
‘o’
+
octave
+
+
‘s’
+
slope
+
+
+
+
+
‘width, w’
+
Specify the band-width of a filter in width_type units.
+
Merge two or more audio streams into a single multi-channel stream.
+
+
The filter accepts the following options:
+
+
+
‘inputs’
+
Set the number of inputs. Default is 2.
+
+
+
+
+
If the channel layouts of the inputs are disjoint, and therefore compatible,
+the channel layout of the output will be set accordingly and the channels
+will be reordered as necessary. If the channel layouts of the inputs are not
+disjoint, the output will have all the channels of the first input then all
+the channels of the second input, in that order, and the channel layout of
+the output will be the default value corresponding to the total number of
+channels.
+
+
For example, if the first input is in 2.1 (FL+FR+LF) and the second input
+is FC+BL+BR, then the output will be in 5.1, with the channels in the
+following order: a1, a2, b1, a3, b2, b3 (a1 is the first channel of the
+first input, b1 is the first channel of the second input).
+
+
On the other hand, if both input are in stereo, the output channels will be
+in the default order: a1, a2, b1, b2, and the channel layout will be
+arbitrarily set to 4.0, which may or may not be the expected value.
+
+
All inputs must have the same sample rate, and format.
+
+
If inputs do not have the same duration, the output will stop with the
+shortest.
+
Pad the end of a audio stream with silence, this can be used together with
+-shortest to extend audio streams to the same length as the video stream.
+
A phaser filter creates series of peaks and troughs in the frequency spectrum.
+The position of the peaks and troughs are modulated so that they vary over time, creating a sweeping effect.
+
+
A description of the accepted parameters follows.
+
Resample the input audio to the specified parameters, using the
+libswresample library. If none are specified then the filter will
+automatically convert between its input and output.
+
+
This filter is also able to stretch/squeeze the audio data to make it match
+the timestamps or to inject silence / cut out audio to make it match the
+timestamps, do a combination of both or do neither.
+
+
The filter accepts the syntax
+[sample_rate:]resampler_options, where sample_rate
+expresses a sample rate and resampler_options is a list of
+key=value pairs, separated by ":". See the
+ffmpeg-resampler manual for the complete list of supported options.
+
Set the number of samples per each output audio frame.
+
+
The last output packet may contain a different number of samples, as
+the filter will flush all the remaining samples when the input audio
+signal its end.
+
+
The filter accepts the following options:
+
+
+
‘nb_out_samples, n’
+
Set the number of frames per each output audio frame. The number is
+intended as the number of samples per each channel.
+Default value is 1024.
+
+
+
‘pad, p’
+
If set to 1, the filter will pad the last audio frame with zeroes, so
+that the last frame will contain the same number of samples as the
+previous ones. Default value is 1.
+
+
+
+
For example, to set the number of per-frame samples to 1234 and
+disable padding for the last frame, use:
+
Display time domain statistical information about the audio channels.
+Statistics are calculated and displayed for each audio channel and,
+where applicable, an overall figure is also given.
+
+
The filter accepts the following option:
+
+
‘length’
+
Short window length in seconds, used for peak and trough RMS measurement.
+Default is 0.05 (50 miliseconds). Allowed range is [0.1 - 10].
+
+
+
+
A description of each shown parameter follows:
+
+
+
‘DC offset’
+
Mean amplitude displacement from zero.
+
+
+
‘Min level’
+
Minimal sample level.
+
+
+
‘Max level’
+
Maximal sample level.
+
+
+
‘Peak level dB’
+
‘RMS level dB’
+
Standard peak and RMS level measured in dBFS.
+
+
+
‘RMS peak dB’
+
‘RMS trough dB’
+
Peak and trough values for RMS level measured over a short window.
+
+
+
‘Crest factor’
+
Standard ratio of peak to RMS level (note: not in dB).
+
+
+
‘Flat factor’
+
Flatness (i.e. consecutive samples with the same value) of the signal at its peak levels
+(i.e. either Min level or Max level).
+
+
+
‘Peak count’
+
Number of occasions (not the number of samples) that the signal attained either
+Min level or Max level.
+
Forward two audio streams and control the order the buffers are forwarded.
+
+
The filter accepts the following options:
+
+
+
‘expr, e’
+
Set the expression deciding which stream should be
+forwarded next: if the result is negative, the first stream is forwarded; if
+the result is positive or zero, the second stream is forwarded. It can use
+the following variables:
+
+
+
b1 b2
+
number of buffers forwarded so far on each stream
+
+
s1 s2
+
number of samples forwarded so far on each stream
+
+
t1 t2
+
current timestamp of each stream
+
+
+
+
The default value is t1-t2, which means to always forward the stream
+that has a smaller timestamp.
+
Synchronize audio data with timestamps by squeezing/stretching it and/or
+dropping samples/adding silence when needed.
+
+
This filter is not built by default, please use aresample to do squeezing/stretching.
+
+
The filter accepts the following named parameters:
+
+
‘compensate’
+
Enable stretching/squeezing the data to make it match the timestamps. Disabled
+by default. When disabled, time gaps are covered with silence.
+
+
+
‘min_delta’
+
Minimum difference between timestamps and audio data (in seconds) to trigger
+adding/dropping samples. Default value is 0.1. If you get non-perfect sync with
+this filter, try setting this parameter to 0.
+
+
+
‘max_comp’
+
Maximum compensation in samples per second. Relevant only with compensate=1.
+Default value 500.
+
+
+
‘first_pts’
+
Assume the first pts should be this value. The time base is 1 / sample rate.
+This allows for padding/trimming at the start of stream. By default, no
+assumption is made about the first frame’s expected pts, so no padding or
+trimming is done. For example, this could be set to 0 to pad the beginning with
+silence if an audio stream starts after the video stream or to trim any samples
+with a negative pts due to encoder delay.
+
The filter accepts exactly one parameter, the audio tempo. If not
+specified then the filter will assume nominal 1.0 tempo. Tempo must
+be in the [0.5, 2.0] range.
+
Trim the input so that the output contains one continuous subpart of the input.
+
+
This filter accepts the following options:
+
+
‘start’
+
Specify time of the start of the kept section, i.e. the audio sample
+with the timestamp start will be the first sample in the output.
+
+
+
‘end’
+
Specify time of the first audio sample that will be dropped, i.e. the
+audio sample immediately preceding the one with the timestamp end will be
+the last sample in the output.
+
+
+
‘start_pts’
+
Same as start, except this option sets the start timestamp in samples
+instead of seconds.
+
+
+
‘end_pts’
+
Same as end, except this option sets the end timestamp in samples instead
+of seconds.
+
+
+
‘duration’
+
Specify maximum duration of the output.
+
+
+
‘start_sample’
+
Number of the first sample that should be passed to output.
+
+
+
‘end_sample’
+
Number of the first sample that should be dropped.
+
+
+
+
‘start’, ‘end’, ‘duration’ are expressed as time
+duration specifications, check the "Time duration" section in the
+ffmpeg-utils manual.
+
+
Note that the first two sets of the start/end options and the ‘duration’
+option look at the frame timestamp, while the _sample options simply count the
+samples that pass through the filter. So start/end_pts and start/end_sample will
+give different results when the timestamps are wrong, inexact or do not start at
+zero. Also note that this filter does not modify the timestamps. If you wish
+that the output timestamps start at zero, insert the asetpts filter after the
+atrim filter.
+
+
If multiple start or end options are set, this filter tries to be greedy and
+keep all samples that match at least one of the specified constraints. To keep
+only the part that matches all the constraints at once, chain multiple atrim
+filters.
+
+
The defaults are such that all the input is kept. So it is possible to set e.g.
+just the end values to keep everything before the specified time.
+
+
Examples:
+
+
+drop everything except the second minute of input
+
Apply a two-pole Butterworth band-pass filter with central
+frequency frequency, and (3dB-point) band-width width.
+The csg option selects a constant skirt gain (peak gain = Q)
+instead of the default: constant 0dB peak gain.
+The filter roll off at 6dB per octave (20dB per decade).
+
+
The filter accepts the following options:
+
+
+
‘frequency, f’
+
Set the filter’s central frequency. Default is 3000.
+
+
+
‘csg’
+
Constant skirt gain if set to 1. Defaults to 0.
+
+
+
‘width_type’
+
Set method to specify band-width of filter.
+
+
‘h’
+
Hz
+
+
‘q’
+
Q-Factor
+
+
‘o’
+
octave
+
+
‘s’
+
slope
+
+
+
+
+
‘width, w’
+
Specify the band-width of a filter in width_type units.
+
Apply a two-pole Butterworth band-reject filter with central
+frequency frequency, and (3dB-point) band-width width.
+The filter roll off at 6dB per octave (20dB per decade).
+
+
The filter accepts the following options:
+
+
+
‘frequency, f’
+
Set the filter’s central frequency. Default is 3000.
+
+
+
‘width_type’
+
Set method to specify band-width of filter.
+
+
‘h’
+
Hz
+
+
‘q’
+
Q-Factor
+
+
‘o’
+
octave
+
+
‘s’
+
slope
+
+
+
+
+
‘width, w’
+
Specify the band-width of a filter in width_type units.
+
Boost or cut the bass (lower) frequencies of the audio using a two-pole
+shelving filter with a response similar to that of a standard
+hi-fi’s tone-controls. This is also known as shelving equalisation (EQ).
+
+
The filter accepts the following options:
+
+
+
‘gain, g’
+
Give the gain at 0 Hz. Its useful range is about -20
+(for a large cut) to +20 (for a large boost).
+Beware of clipping when using a positive gain.
+
+
+
‘frequency, f’
+
Set the filter’s central frequency and so can be used
+to extend or reduce the frequency range to be boosted or cut.
+The default value is 100 Hz.
+
+
+
‘width_type’
+
Set method to specify band-width of filter.
+
+
‘h’
+
Hz
+
+
‘q’
+
Q-Factor
+
+
‘o’
+
octave
+
+
‘s’
+
slope
+
+
+
+
+
‘width, w’
+
Determine how steep is the filter’s shelf transition.
+
Apply a biquad IIR filter with the given coefficients.
+Where b0, b1, b2 and a0, a1, a2
+are the numerator and denominator coefficients respectively.
+
This filter accepts the following named parameters:
+
+
‘channel_layout’
+
Channel layout of the output stream.
+
+
+
‘map’
+
Map channels from input to output. The argument is a ’|’-separated list of
+mappings, each in the in_channel-out_channel or
+in_channel form. in_channel can be either the name of the input
+channel (e.g. FL for front left) or its index in the input channel layout.
+out_channel is the name of the output channel or its index in the output
+channel layout. If out_channel is not given then it is implicitly an
+index, starting with zero and increasing by one for each mapping.
+
+
+
+
If no mapping is present, the filter will implicitly map input channels to
+output channels preserving index.
+
+
For example, assuming a 5.1+downmix input MOV file
+
Set list of times in seconds for each channel over which the instantaneous
+level of the input signal is averaged to determine its volume.
+‘attacks’ refers to increase of volume and ‘decays’ refers
+to decrease of volume.
+For most situations, the attack time (response to the audio getting louder)
+should be shorter than the decay time because the human ear is more sensitive
+to sudden loud audio than sudden soft audio.
+Typical value for attack is 0.3 seconds and for decay 0.8
+seconds.
+
+
+
‘points’
+
Set list of points for transfer function, specified in dB relative to maximum
+possible signal amplitude.
+Each key points list need to be defined using the following syntax:
+x0/y0 x1/y1 x2/y2 ....
+
+
The input values must be in strictly increasing order but the transfer
+function does not have to be monotonically rising.
+The point 0/0 is assumed but may be overridden (by 0/out-dBn).
+Typical values for the transfer function are -70/-70 -60/-20.
+
+
+
‘soft-knee’
+
Set amount for which the points at where adjacent line segments on the
+transfer function meet will be rounded. Defaults is 0.01.
+
+
+
‘gain’
+
Set additional gain in dB to be applied at all points on the transfer function
+and allows easy adjustment of the overall gain.
+Default is 0.
+
+
+
‘volume’
+
Set initial volume in dB to be assumed for each channel when filtering starts.
+This permits the user to supply a nominal level initially, so that,
+for example, a very large gain is not applied to initial signal levels before
+the companding has begun to operate. A typical value for audio which is
+initially quiet is -90 dB. Default is 0.
+
+
+
‘delay’
+
Set delay in seconds. Default is 0. The input audio
+is analysed immediately, but audio is delayed before being fed to the
+volume adjuster. Specifying a delay approximately equal to the attack/decay
+times allows the filter to effectively operate in predictive rather than
+reactive mode.
+
This filter adds ‘cues’ to 44.1kHz stereo (i.e. audio CD format) audio
+so that when listened to on headphones the stereo image is moved from
+inside your head (standard for headphones) to outside and in front of
+the listener (standard for speakers).
+
Apply a two-pole peaking equalisation (EQ) filter. With this
+filter, the signal-level at and around a selected frequency can
+be increased or decreased, whilst (unlike bandpass and bandreject
+filters) that at all other frequencies is unchanged.
+
+
In order to produce complex equalisation curves, this filter can
+be given several times, each with a different central frequency.
+
+
The filter accepts the following options:
+
+
+
‘frequency, f’
+
Set the filter’s central frequency in Hz.
+
+
+
‘width_type’
+
Set method to specify band-width of filter.
+
+
‘h’
+
Hz
+
+
‘q’
+
Q-Factor
+
+
‘o’
+
octave
+
+
‘s’
+
slope
+
+
+
+
+
‘width, w’
+
Specify the band-width of a filter in width_type units.
+
+
+
‘gain, g’
+
Set the required gain or attenuation in dB.
+Beware of clipping when using a positive gain.
+
Apply a high-pass filter with 3dB point frequency.
+The filter can be either single-pole, or double-pole (the default).
+The filter roll off at 6dB per pole per octave (20dB per pole per decade).
+
+
The filter accepts the following options:
+
+
+
‘frequency, f’
+
Set frequency in Hz. Default is 3000.
+
+
+
‘poles, p’
+
Set number of poles. Default is 2.
+
+
+
‘width_type’
+
Set method to specify band-width of filter.
+
+
‘h’
+
Hz
+
+
‘q’
+
Q-Factor
+
+
‘o’
+
octave
+
+
‘s’
+
slope
+
+
+
+
+
‘width, w’
+
Specify the band-width of a filter in width_type units.
+Applies only to double-pole filter.
+The default is 0.707q and gives a Butterworth response.
+
Join multiple input streams into one multi-channel stream.
+
+
The filter accepts the following named parameters:
+
+
‘inputs’
+
Number of input streams. Defaults to 2.
+
+
+
‘channel_layout’
+
Desired output channel layout. Defaults to stereo.
+
+
+
‘map’
+
Map channels from inputs to output. The argument is a ’|’-separated list of
+mappings, each in the input_idx.in_channel-out_channel
+form. input_idx is the 0-based index of the input stream. in_channel
+can be either the name of the input channel (e.g. FL for front left) or its
+index in the specified input stream. out_channel is the name of the output
+channel.
+
+
+
+
The filter will attempt to guess the mappings when those are not specified
+explicitly. It does so by first trying to find an unused matching input channel
+and if that fails it picks the first unused input channel.
+
+
E.g. to join 3 inputs (with properly set channel layouts)
+
To enable compilation of this filter you need to configure FFmpeg with
+--enable-ladspa.
+
+
+
‘file, f’
+
Specifies the name of LADSPA plugin library to load. If the environment
+variable LADSPA_PATH is defined, the LADSPA plugin is searched in
+each one of the directories specified by the colon separated list in
+LADSPA_PATH, otherwise in the standard LADSPA paths, which are in
+this order: ‘HOME/.ladspa/lib/’, ‘/usr/local/lib/ladspa/’,
+‘/usr/lib/ladspa/’.
+
+
+
‘plugin, p’
+
Specifies the plugin within the library. Some libraries contain only
+one plugin, but others contain many of them. If this is not set filter
+will list all available plugins within the specified library.
+
+
+
‘controls, c’
+
Set the ’|’ separated list of controls which are zero or more floating point
+values that determine the behavior of the loaded plugin (for example delay,
+threshold or gain).
+Controls need to be defined using the following syntax:
+c0=value0|c1=value1|c2=value2|..., where
+valuei is the value set on the i-th control.
+If ‘controls’ is set to help, all available controls and
+their valid ranges are printed.
+
+
+
‘sample_rate, s’
+
Specify the sample rate, default to 44100. Only used if plugin have
+zero inputs.
+
+
+
‘nb_samples, n’
+
Set the number of samples per channel per each output frame, default
+is 1024. Only used if plugin have zero inputs.
+
+
+
‘duration, d’
+
Set the minimum duration of the sourced audio. See the function
+av_parse_time() for the accepted format, also check the "Time duration"
+section in the ffmpeg-utils manual.
+Note that the resulting duration may be greater than the specified duration,
+as the generated audio is always cut at the end of a complete frame.
+If not specified, or the expressed duration is negative, the audio is
+supposed to be generated forever.
+Only used if plugin have zero inputs.
+
Apply a low-pass filter with 3dB point frequency.
+The filter can be either single-pole or double-pole (the default).
+The filter roll off at 6dB per pole per octave (20dB per pole per decade).
+
+
The filter accepts the following options:
+
+
+
‘frequency, f’
+
Set frequency in Hz. Default is 500.
+
+
+
‘poles, p’
+
Set number of poles. Default is 2.
+
+
+
‘width_type’
+
Set method to specify band-width of filter.
+
+
‘h’
+
Hz
+
+
‘q’
+
Q-Factor
+
+
‘o’
+
octave
+
+
‘s’
+
slope
+
+
+
+
+
‘width, w’
+
Specify the band-width of a filter in width_type units.
+Applies only to double-pole filter.
+The default is 0.707q and gives a Butterworth response.
+
Mix channels with specific gain levels. The filter accepts the output
+channel layout followed by a set of channels definitions.
+
+
This filter is also designed to remap efficiently the channels of an audio
+stream.
+
+
The filter accepts parameters of the form:
+"l:outdef:outdef:..."
+
+
+
‘l’
+
output channel layout or number of channels
+
+
+
‘outdef’
+
output channel specification, of the form:
+"out_name=[gain*]in_name[+[gain*]in_name...]"
+
+
+
‘out_name’
+
output channel to define, either a channel name (FL, FR, etc.) or a channel
+number (c0, c1, etc.)
+
+
+
‘gain’
+
multiplicative coefficient for the channel, 1 leaving the volume unchanged
+
+
+
‘in_name’
+
input channel to use, see out_name for details; it is not possible to mix
+named and numbered input channels
+
+
+
+
If the ‘=’ in a channel specification is replaced by ‘<’, then the gains for
+that specification will be renormalized so that the total is 1, thus
+avoiding clipping noise.
+
Note that ffmpeg integrates a default down-mix (and up-mix) system
+that should be preferred (see "-ac" option) unless you have very specific
+needs.
+
The channel remapping will be effective if, and only if:
+
+
+
gain coefficients are zeroes or ones,
+
only one input per channel output,
+
+
+
If all these conditions are satisfied, the filter will notify the user ("Pure
+channel mapping detected"), and use an optimized and lossless method to do the
+remapping.
+
+
For example, if you have a 5.1 source and want a stereo audio stream by
+dropping the extra channels:
+
pan="stereo: c0=FL : c1=FR"
+
+
+
Given the same source, you can also switch front left and front right channels
+and keep the input channel layout:
+
ReplayGain scanner filter. This filter takes an audio stream as an input and
+outputs it unchanged.
+At end of filtering it displays track_gain and track_peak.
+
This filter logs a message when it detects that the input audio volume is less
+or equal to a noise tolerance value for a duration greater or equal to the
+minimum detected noise duration.
+
+
The printed times and duration are expressed in seconds.
+
+
The filter accepts the following options:
+
+
+
‘duration, d’
+
Set silence duration until notification (default is 2 seconds).
+
+
+
‘noise, n’
+
Set noise tolerance. Can be specified in dB (in case "dB" is appended to the
+specified value) or amplitude ratio. Default is -60dB, or 0.001.
+
Boost or cut treble (upper) frequencies of the audio using a two-pole
+shelving filter with a response similar to that of a standard
+hi-fi’s tone-controls. This is also known as shelving equalisation (EQ).
+
+
The filter accepts the following options:
+
+
+
‘gain, g’
+
Give the gain at whichever is the lower of ~22 kHz and the
+Nyquist frequency. Its useful range is about -20 (for a large cut)
+to +20 (for a large boost). Beware of clipping when using a positive gain.
+
+
+
‘frequency, f’
+
Set the filter’s central frequency and so can be used
+to extend or reduce the frequency range to be boosted or cut.
+The default value is 3000 Hz.
+
+
+
‘width_type’
+
Set method to specify band-width of filter.
+
+
‘h’
+
Hz
+
+
‘q’
+
Q-Factor
+
+
‘o’
+
octave
+
+
‘s’
+
slope
+
+
+
+
+
‘width, w’
+
Determine how steep is the filter’s shelf transition.
+
The filter has no parameters. The input is not modified. Statistics about
+the volume will be printed in the log when the input stream end is reached.
+
+
In particular it will show the mean volume (root mean square), maximum
+volume (on a per-sample basis), and the beginning of a histogram of the
+registered volume values (from the maximum value to a cumulated 1/1000 of
+the samples).
+
+
All volumes are in decibels relative to the maximum PCM value.
+
Buffer audio frames, and make them available to the filter chain.
+
+
This source is mainly intended for a programmatic use, in particular
+through the interface defined in ‘libavfilter/asrc_abuffer.h’.
+
+
It accepts the following named parameters:
+
+
+
‘time_base’
+
Timebase which will be used for timestamps of submitted frames. It must be
+either a floating-point number or in numerator/denominator form.
+
+
+
‘sample_rate’
+
The sample rate of the incoming audio buffers.
+
+
+
‘sample_fmt’
+
The sample format of the incoming audio buffers.
+Either a sample format name or its corresponging integer representation from
+the enum AVSampleFormat in ‘libavutil/samplefmt.h’
+
+
+
‘channel_layout’
+
The channel layout of the incoming audio buffers.
+Either a channel layout name from channel_layout_map in
+‘libavutil/channel_layout.c’ or its corresponding integer representation
+from the AV_CH_LAYOUT_* macros in ‘libavutil/channel_layout.h’
+
+
+
‘channels’
+
The number of channels of the incoming audio buffers.
+If both channels and channel_layout are specified, then they
+must be consistent.
+
will instruct the source to accept planar 16bit signed stereo at 44100Hz.
+Since the sample format with name "s16p" corresponds to the number
+6 and the "stereo" channel layout corresponds to the value 0x3, this is
+equivalent to:
+
Generate an audio signal specified by an expression.
+
+
This source accepts in input one or more expressions (one for each
+channel), which are evaluated and used to generate a corresponding
+audio signal.
+
+
This source accepts the following options:
+
+
+
‘exprs’
+
Set the ’|’-separated expressions list for each separate channel. In case the
+‘channel_layout’ option is not specified, the selected channel layout
+depends on the number of provided expressions.
+
+
+
‘channel_layout, c’
+
Set the channel layout. The number of channels in the specified layout
+must be equal to the number of specified expressions.
+
+
+
‘duration, d’
+
Set the minimum duration of the sourced audio. See the function
+av_parse_time() for the accepted format.
+Note that the resulting duration may be greater than the specified
+duration, as the generated audio is always cut at the end of a
+complete frame.
+
+
If not specified, or the expressed duration is negative, the audio is
+supposed to be generated forever.
+
+
+
‘nb_samples, n’
+
Set the number of samples per channel per each output frame,
+default to 1024.
+
+
+
‘sample_rate, s’
+
Specify the sample rate, default to 44100.
+
+
+
+
Each expression in exprs can contain the following constants:
+
+
+
‘n’
+
number of the evaluated sample, starting from 0
+
+
+
‘t’
+
time of the evaluated sample expressed in seconds, starting from 0
+
Null audio source, return unprocessed audio frames. It is mainly useful
+as a template and to be employed in analysis / debugging tools, or as
+the source for filters which ignore the input data (for example the sox
+synth filter).
+
+
This source accepts the following options:
+
+
+
‘channel_layout, cl’
+
+
Specify the channel layout, and can be either an integer or a string
+representing a channel layout. The default value of channel_layout
+is "stereo".
+
+
Check the channel_layout_map definition in
+‘libavutil/channel_layout.c’ for the mapping between strings and
+channel layout values.
+
Buffer audio frames, and make them available to the end of filter chain.
+
+
This sink is mainly intended for programmatic use, in particular
+through the interface defined in ‘libavfilter/buffersink.h’
+or the options system.
+
+
It accepts a pointer to an AVABufferSinkContext structure, which
+defines the incoming buffers’ formats, to be passed as the opaque
+parameter to avfilter_init_filter for initialization.
+
When you configure your FFmpeg build, you can disable any of the
+existing filters using --disable-filters.
+The configure output will show the video filters included in your
+build.
+
+
Below is a description of the currently available video filters.
+
Add or replace the alpha component of the primary input with the
+grayscale value of a second input. This is intended for use with
+alphaextract to allow the transmission or storage of frame
+sequences that have alpha in a format that doesn’t support an alpha
+channel.
+
+
For example, to reconstruct full frames from a normal YUV-encoded video
+and a separate video created with alphaextract, you might use:
+
Since this filter is designed for reconstruction, it operates on frame
+sequences without considering timestamps, and terminates when either
+input reaches end of stream. This will cause problems if your encoding
+pipeline drops frames. If you’re trying to apply an image as an
+overlay to a video stream, consider the overlay filter instead.
+
Same as the subtitles filter, except that it doesn’t require libavcodec
+and libavformat to work. On the other hand, it is limited to ASS (Advanced
+Substation Alpha) subtitles files.
+
Compute the bounding box for the non-black pixels in the input frame
+luminance plane.
+
+
This filter computes the bounding box containing all the pixels with a
+luminance value greater than the minimum allowed value.
+The parameters describing the bounding box are printed on the filter
+log.
+
Detect video intervals that are (almost) completely black. Can be
+useful to detect chapter transitions, commercials, or invalid
+recordings. Output lines contains the time for the start, end and
+duration of the detected black interval expressed in seconds.
+
+
In order to display the output lines, you need to set the loglevel at
+least to the AV_LOG_INFO value.
+
+
The filter accepts the following options:
+
+
+
‘black_min_duration, d’
+
Set the minimum detected black duration expressed in seconds. It must
+be a non-negative floating point number.
+
+
Default value is 2.0.
+
+
+
‘picture_black_ratio_th, pic_th’
+
Set the threshold for considering a picture "black".
+Express the minimum value for the ratio:
+
nb_black_pixels / nb_pixels
+
+
+
for which a picture is considered black.
+Default value is 0.98.
+
+
+
‘pixel_black_th, pix_th’
+
Set the threshold for considering a pixel "black".
+
+
The threshold expresses the maximum pixel luminance value for which a
+pixel is considered "black". The provided value is scaled according to
+the following equation:
+
luminance_range_size and luminance_minimum_value depend on
+the input video format, the range is [0-255] for YUV full-range
+formats and [16-235] for YUV non full-range formats.
+
+
Default value is 0.10.
+
+
+
+
The following example sets the maximum pixel threshold to the minimum
+value, and detects only black intervals of 2 or more seconds:
+
Detect frames that are (almost) completely black. Can be useful to
+detect chapter transitions or commercials. Output lines consist of
+the frame number of the detected frame, the percentage of blackness,
+the position in the file if known or -1 and the timestamp in seconds.
+
+
In order to display the output lines, you need to set the loglevel at
+least to the AV_LOG_INFO value.
+
+
The filter accepts the following options:
+
+
+
‘amount’
+
Set the percentage of the pixels that have to be below the threshold, defaults
+to 98.
+
+
+
‘threshold, thresh’
+
Set the threshold below which a pixel value is considered black, defaults to
+32.
+
It takes two input streams and outputs one stream, the first input is the
+"top" layer and second input is "bottom" layer.
+Output terminates when shortest input terminates.
+
+
A description of the accepted options follows.
+
+
+
‘c0_mode’
+
‘c1_mode’
+
‘c2_mode’
+
‘c3_mode’
+
‘all_mode’
+
Set blend mode for specific pixel component or all pixel components in case
+of all_mode. Default value is normal.
+
+
Available values for component modes are:
+
+
‘addition’
+
‘and’
+
‘average’
+
‘burn’
+
‘darken’
+
‘difference’
+
‘divide’
+
‘dodge’
+
‘exclusion’
+
‘hardlight’
+
‘lighten’
+
‘multiply’
+
‘negation’
+
‘normal’
+
‘or’
+
‘overlay’
+
‘phoenix’
+
‘pinlight’
+
‘reflect’
+
‘screen’
+
‘softlight’
+
‘subtract’
+
‘vividlight’
+
‘xor’
+
+
+
+
‘c0_opacity’
+
‘c1_opacity’
+
‘c2_opacity’
+
‘c3_opacity’
+
‘all_opacity’
+
Set blend opacity for specific pixel component or all pixel components in case
+of all_opacity. Only used in combination with pixel component blend modes.
+
+
+
‘c0_expr’
+
‘c1_expr’
+
‘c2_expr’
+
‘c3_expr’
+
‘all_expr’
+
Set blend expression for specific pixel component or all pixel components in case
+of all_expr. Note that related mode options will be ignored if those are set.
+
+
The expressions can use the following variables:
+
+
+
‘N’
+
The sequential number of the filtered frame, starting from 0.
+
+
+
‘X’
+
‘Y’
+
the coordinates of the current sample
+
+
+
‘W’
+
‘H’
+
the width and height of currently filtered plane
+
+
+
‘SW’
+
‘SH’
+
Width and height scale depending on the currently filtered plane. It is the
+ratio between the corresponding luma plane number of pixels and the current
+plane ones. E.g. for YUV4:2:0 the values are 1,1 for the luma plane, and
+0.5,0.5 for chroma planes.
+
+
+
‘T’
+
Time of the current frame, expressed in seconds.
+
+
+
‘TOP, A’
+
Value of pixel component at current location for first video frame (top layer).
+
+
+
‘BOTTOM, B’
+
Value of pixel component at current location for second video frame (bottom layer).
+
+
+
+
+
‘shortest’
+
Force termination when the shortest input terminates. Default is 0.
+
+
‘repeatlast’
+
Continue applying the last bottom frame after the end of the stream. A value of
+0 disable the filter after the last frame of the bottom layer is reached.
+Default is 1.
+
Set an expression for the box radius in pixels used for blurring the
+corresponding input plane.
+
+
The radius value must be a non-negative number, and must not be
+greater than the value of the expression min(w,h)/2 for the
+luma and alpha planes, and of min(cw,ch)/2 for the chroma
+planes.
+
+
Default value for ‘luma_radius’ is "2". If not specified,
+‘chroma_radius’ and ‘alpha_radius’ default to the
+corresponding value set for ‘luma_radius’.
+
+
The expressions can contain the following constants:
+
+
‘w’
+
‘h’
+
the input width and height in pixels
+
+
+
‘cw’
+
‘ch’
+
the input chroma image width and height in pixels
+
+
+
‘hsub’
+
‘vsub’
+
horizontal and vertical chroma subsample values. For example for the
+pixel format "yuv422p" hsub is 2 and vsub is 1.
+
+
+
+
+
‘luma_power, lp’
+
‘chroma_power, cp’
+
‘alpha_power, ap’
+
Specify how many times the boxblur filter is applied to the
+corresponding plane.
+
+
Default value for ‘luma_power’ is 2. If not specified,
+‘chroma_power’ and ‘alpha_power’ default to the
+corresponding value set for ‘luma_power’.
+
Modify intensity of primary colors (red, green and blue) of input frames.
+
+
The filter allows an input frame to be adjusted in the shadows, midtones or highlights
+regions for the red-cyan, green-magenta or blue-yellow balance.
+
+
A positive adjustment value shifts the balance towards the primary color, a negative
+value towards the complementary color.
+
+
The filter accepts the following options:
+
+
+
‘rs’
+
‘gs’
+
‘bs’
+
Adjust red, green and blue shadows (darkest pixels).
+
+
+
‘rm’
+
‘gm’
+
‘bm’
+
Adjust red, green and blue midtones (medium pixels).
+
+
+
‘rh’
+
‘gh’
+
‘bh’
+
Adjust red, green and blue highlights (brightest pixels).
+
+
Allowed ranges for options are [-1.0, 1.0]. Defaults are 0.
+
Adjust video input frames by re-mixing color channels.
+
+
This filter modifies a color channel by adding the values associated to
+the other channels of the same pixels. For example if the value to
+modify is red, the output value will be:
+
red=red*rr + blue*rb + green*rg + alpha*ra
+
+
+
The filter accepts the following options:
+
+
+
‘rr’
+
‘rg’
+
‘rb’
+
‘ra’
+
Adjust contribution of input red, green, blue and alpha channels for output red channel.
+Default is 1 for rr, and 0 for rg, rb and ra.
+
+
+
‘gr’
+
‘gg’
+
‘gb’
+
‘ga’
+
Adjust contribution of input red, green, blue and alpha channels for output green channel.
+Default is 1 for gg, and 0 for gr, gb and ga.
+
+
+
‘br’
+
‘bg’
+
‘bb’
+
‘ba’
+
Adjust contribution of input red, green, blue and alpha channels for output blue channel.
+Default is 1 for bb, and 0 for br, bg and ba.
+
+
+
‘ar’
+
‘ag’
+
‘ab’
+
‘aa’
+
Adjust contribution of input red, green, blue and alpha channels for output alpha channel.
+Default is 1 for aa, and 0 for ar, ag and ab.
+
Width of the output video. It defaults to iw.
+This expression is evaluated only once during the filter
+configuration.
+
+
+
‘h, out_h’
+
Height of the output video. It defaults to ih.
+This expression is evaluated only once during the filter
+configuration.
+
+
+
‘x’
+
Horizontal position, in the input video, of the left edge of the output video.
+It defaults to (in_w-out_w)/2.
+This expression is evaluated per-frame.
+
+
+
‘y’
+
Vertical position, in the input video, of the top edge of the output video.
+It defaults to (in_h-out_h)/2.
+This expression is evaluated per-frame.
+
+
+
‘keep_aspect’
+
If set to 1 will force the output display aspect ratio
+to be the same of the input, by changing the output sample aspect
+ratio. It defaults to 0.
+
+
+
+
The out_w, out_h, x, y parameters are
+expressions containing the following constants:
+
+
+
‘x’
+
‘y’
+
the computed values for x and y. They are evaluated for
+each new frame.
+
+
+
‘in_w’
+
‘in_h’
+
the input width and height
+
+
+
‘iw’
+
‘ih’
+
same as in_w and in_h
+
+
+
‘out_w’
+
‘out_h’
+
the output (cropped) width and height
+
+
+
‘ow’
+
‘oh’
+
same as out_w and out_h
+
+
+
‘a’
+
same as iw / ih
+
+
+
‘sar’
+
input sample aspect ratio
+
+
+
‘dar’
+
input display aspect ratio, it is the same as (iw / ih) * sar
+
+
+
‘hsub’
+
‘vsub’
+
horizontal and vertical chroma subsample values. For example for the
+pixel format "yuv422p" hsub is 2 and vsub is 1.
+
+
+
‘n’
+
the number of input frame, starting from 0
+
+
+
‘pos’
+
the position in the file of the input frame, NAN if unknown
+
+
+
‘t’
+
timestamp expressed in seconds, NAN if the input timestamp is unknown
+
+
+
+
+
The expression for out_w may depend on the value of out_h,
+and the expression for out_h may depend on out_w, but they
+cannot depend on x and y, as x and y are
+evaluated after out_w and out_h.
+
+
The x and y parameters specify the expressions for the
+position of the top-left corner of the output (non-cropped) area. They
+are evaluated for each frame. If the evaluated value is not valid, it
+is approximated to the nearest valid value.
+
+
The expression for x may depend on y, and the expression
+for y may depend on x.
+
+Crop area with size 100x100 at position (12,34).
+
crop=100:100:12:34
+
+
+
Using named options, the example above becomes:
+
crop=w=100:h=100:x=12:y=34
+
+
+
+Crop the central input area with size 100x100:
+
crop=100:100
+
+
+
+Crop the central input area with size 2/3 of the input video:
+
crop=2/3*in_w:2/3*in_h
+
+
+
+Crop the input video central square:
+
crop=out_w=in_h
+crop=in_h
+
+
+
+Delimit the rectangle with the top-left corner placed at position
+100:100 and the right-bottom corner corresponding to the right-bottom
+corner of the input image:
+
crop=in_w-100:in_h-100:100:100
+
+
+
+Crop 10 pixels from the left and right borders, and 20 pixels from
+the top and bottom borders
+
crop=in_w-2*10:in_h-2*20
+
+
+
+Keep only the bottom right quarter of the input image:
+
Calculate necessary cropping parameters and prints the recommended
+parameters through the logging system. The detected dimensions
+correspond to the non-black area of the input video.
+
+
The filter accepts the following options:
+
+
+
‘limit’
+
Set higher black value threshold, which can be optionally specified
+from nothing (0) to everything (255). An intensity value greater
+to the set value is considered non-black. Default value is 24.
+
+
+
‘round’
+
Set the value for which the width/height should be divisible by. The
+offset is automatically adjusted to center the video. Use 2 to get
+only even dimensions (needed for 4:2:2 video). 16 is best when
+encoding to most video codecs. Default value is 16.
+
+
+
‘reset_count, reset’
+
Set the counter that determines after how many frames cropdetect will
+reset the previously detected largest video area and start over to
+detect the current optimal crop area. Default value is 0.
+
+
This can be useful when channel logos distort the video area. 0
+indicates never reset and return the largest area encountered during
+playback.
+
This filter is similar to the Adobe Photoshop and GIMP curves tools. Each
+component (red, green and blue) has its values defined by N key points
+tied from each other using a smooth curve. The x-axis represents the pixel
+values from the input frame, and the y-axis the new pixel values to be set for
+the output frame.
+
+
By default, a component curve is defined by the two points (0;0) and
+(1;1). This creates a straight line where each original pixel value is
+"adjusted" to its own value, which means no change to the image.
+
+
The filter allows you to redefine these two points and add some more. A new
+curve (using a natural cubic spline interpolation) will be define to pass
+smoothly through all these new coordinates. The new defined points needs to be
+strictly increasing over the x-axis, and their x and y values must
+be in the [0;1] interval. If the computed curves happened to go outside
+the vector spaces, the values will be clipped accordingly.
+
+
If there is no key point defined in x=0, the filter will automatically
+insert a (0;0) point. In the same way, if there is no key point defined
+in x=1, the filter will automatically insert a (1;1) point.
+
+
The filter accepts the following options:
+
+
+
‘preset’
+
Select one of the available color presets. This option can be used in addition
+to the ‘r’, ‘g’, ‘b’ parameters; in this case, the later
+options takes priority on the preset values.
+Available presets are:
+
+
‘none’
+
‘color_negative’
+
‘cross_process’
+
‘darker’
+
‘increase_contrast’
+
‘lighter’
+
‘linear_contrast’
+
‘medium_contrast’
+
‘negative’
+
‘strong_contrast’
+
‘vintage’
+
+
Default is none.
+
+
‘master, m’
+
Set the master key points. These points will define a second pass mapping. It
+is sometimes called a "luminance" or "value" mapping. It can be used with
+‘r’, ‘g’, ‘b’ or ‘all’ since it acts like a
+post-processing LUT.
+
+
‘red, r’
+
Set the key points for the red component.
+
+
‘green, g’
+
Set the key points for the green component.
+
+
‘blue, b’
+
Set the key points for the blue component.
+
+
‘all’
+
Set the key points for all components (not including master).
+Can be used in addition to the other key points component
+options. In this case, the unset component(s) will fallback on this
+‘all’ setting.
+
+
‘psfile’
+
Specify a Photoshop curves file (.asv) to import the settings from.
+
+
+
+
To avoid some filtergraph syntax conflicts, each key points list need to be
+defined using the following syntax: x0/y0 x1/y1 x2/y2 ....
+
Denoise frames using 2D DCT (frequency domain filtering).
+
+
This filter is not designed for real time and can be extremely slow.
+
+
The filter accepts the following options:
+
+
+
‘sigma, s’
+
Set the noise sigma constant.
+
+
This sigma defines a hard threshold of 3 * sigma; every DCT
+coefficient (absolute value) below this threshold with be dropped.
+
+
If you need a more advanced filtering, see ‘expr’.
+
+
Default is 0.
+
+
+
‘overlap’
+
Set number overlapping pixels for each block. Each block is of size
+16x16. Since the filter can be slow, you may want to reduce this value,
+at the cost of a less effective filter and the risk of various artefacts.
+
+
If the overlapping value doesn’t allow to process the whole input width or
+height, a warning will be displayed and according borders won’t be denoised.
+
+
Default value is 15.
+
+
+
‘expr, e’
+
Set the coefficient factor expression.
+
+
For each coefficient of a DCT block, this expression will be evaluated as a
+multiplier value for the coefficient.
+
+
If this is option is set, the ‘sigma’ option will be ignored.
+
+
The absolute value of the coefficient can be accessed through the c
+variable.
+
Set the number of frames from which one will be dropped. Setting this to
+N means one frame in every batch of N frames will be dropped.
+Default is 5.
+
+
+
‘dupthresh’
+
Set the threshold for duplicate detection. If the difference metric for a frame
+is less than or equal to this value, then it is declared as duplicate. Default
+is 1.1
+
+
+
‘scthresh’
+
Set scene change threshold. Default is 15.
+
+
+
‘blockx’
+
‘blocky’
+
Set the size of the x and y-axis blocks used during metric calculations.
+Larger blocks give better noise suppression, but also give worse detection of
+small movements. Must be a power of two. Default is 32.
+
+
+
‘ppsrc’
+
Mark main input as a pre-processed input and activate clean source input
+stream. This allows the input to be pre-processed with various filters to help
+the metrics calculation while keeping the frame selection lossless. When set to
+1, the first stream is for the pre-processed input, and the second
+stream is the clean source from where the kept frames are chosen. Default is
+0.
+
+
+
‘chroma’
+
Set whether or not chroma is considered in the metric calculations. Default is
+1.
+
Suppress a TV station logo by a simple interpolation of the surrounding
+pixels. Just set a rectangle covering the logo and watch it disappear
+(and sometimes something even uglier appear - your mileage may vary).
+
+
This filter accepts the following options:
+
+
‘x’
+
‘y’
+
Specify the top left corner coordinates of the logo. They must be
+specified.
+
+
+
‘w’
+
‘h’
+
Specify the width and height of the logo to clear. They must be
+specified.
+
+
+
‘band, t’
+
Specify the thickness of the fuzzy edge of the rectangle (added to
+w and h). The default value is 4.
+
+
+
‘show’
+
When set to 1, a green rectangle is drawn on the screen to simplify
+finding the right x, y, w, and h parameters.
+The default value is 0.
+
+
The rectangle is drawn on the outermost pixels which will be (partly)
+replaced with interpolated values. The values of the next pixels
+immediately outside this rectangle in each direction will be used to
+compute the interpolated pixel values inside the rectangle.
+
Attempt to fix small changes in horizontal and/or vertical shift. This
+filter helps remove camera shake from hand-holding a camera, bumping a
+tripod, moving on a vehicle, etc.
+
+
The filter accepts the following options:
+
+
+
‘x’
+
‘y’
+
‘w’
+
‘h’
+
Specify a rectangular area where to limit the search for motion
+vectors.
+If desired the search for motion vectors can be limited to a
+rectangular area of the frame defined by its top left corner, width
+and height. These parameters have the same meaning as the drawbox
+filter which can be used to visualise the position of the bounding
+box.
+
+
This is useful when simultaneous movement of subjects within the frame
+might be confused for camera motion by the motion vector search.
+
+
If any or all of x, y, w and h are set to -1
+then the full frame is used. This allows later options to be set
+without specifying the bounding box for the motion vector search.
+
+
Default - search the whole frame.
+
+
+
‘rx’
+
‘ry’
+
Specify the maximum extent of movement in x and y directions in the
+range 0-64 pixels. Default 16.
+
+
+
‘edge’
+
Specify how to generate pixels to fill blanks at the edge of the
+frame. Available values are:
+
+
‘blank, 0’
+
Fill zeroes at blank locations
+
+
‘original, 1’
+
Original image at blank locations
+
+
‘clamp, 2’
+
Extruded edge value at blank locations
+
+
‘mirror, 3’
+
Mirrored edge at blank locations
+
+
+
Default value is ‘mirror’.
+
+
+
‘blocksize’
+
Specify the blocksize to use for motion search. Range 4-128 pixels,
+default 8.
+
+
+
‘contrast’
+
Specify the contrast threshold for blocks. Only blocks with more than
+the specified contrast (difference between darkest and lightest
+pixels) will be considered. Range 1-255, default 125.
+
+
+
‘search’
+
Specify the search strategy. Available values are:
+
+
‘exhaustive, 0’
+
Set exhaustive search
+
+
‘less, 1’
+
Set less exhaustive search.
+
+
+
Default value is ‘exhaustive’.
+
+
+
‘filename’
+
If set then a detailed log of the motion search is written to the
+specified file.
+
+
+
‘opencl’
+
If set to 1, specify using OpenCL capabilities, only available if
+FFmpeg was configured with --enable-opencl. Default value is 0.
+
The expressions which specify the top left corner coordinates of the box. Default to 0.
+
+
+
‘width, w’
+
‘height, h’
+
The expressions which specify the width and height of the box, if 0 they are interpreted as
+the input width and height. Default to 0.
+
+
+
‘color, c’
+
Specify the color of the box to write. For the general syntax of this option,
+check the "Color" section in the ffmpeg-utils manual. If the special
+value invert is used, the box edge color is the same as the
+video with inverted luma.
+
+
+
‘thickness, t’
+
The expression which sets the thickness of the box edge. Default value is 3.
+
+
See below for the list of accepted constants.
+
+
+
+
The parameters for x, y, w and h and t are expressions containing the
+following constants:
+
+
+
‘dar’
+
The input display aspect ratio, it is the same as (w / h) * sar.
+
+
+
‘hsub’
+
‘vsub’
+
horizontal and vertical chroma subsample values. For example for the
+pixel format "yuv422p" hsub is 2 and vsub is 1.
+
+
+
‘in_h, ih’
+
‘in_w, iw’
+
The input width and height.
+
+
+
‘sar’
+
The input sample aspect ratio.
+
+
+
‘x’
+
‘y’
+
The x and y offset coordinates where the box is drawn.
+
+
+
‘w’
+
‘h’
+
The width and height of the drawn box.
+
+
+
‘t’
+
The thickness of the drawn box.
+
+
These constants allow the x, y, w, h and t expressions to refer to
+each other, so you may for example specify y=x/dar or h=w/dar.
+
The expressions which specify the coordinates of some point of grid intersection (meant to configure offset). Both default to 0.
+
+
+
‘width, w’
+
‘height, h’
+
The expressions which specify the width and height of the grid cell, if 0 they are interpreted as the
+input width and height, respectively, minus thickness, so image gets
+framed. Default to 0.
+
+
+
‘color, c’
+
Specify the color of the grid. For the general syntax of this option,
+check the "Color" section in the ffmpeg-utils manual. If the special
+value invert is used, the grid color is the same as the
+video with inverted luma.
+
+
+
‘thickness, t’
+
The expression which sets the thickness of the grid line. Default value is 1.
+
+
See below for the list of accepted constants.
+
+
+
+
The parameters for x, y, w and h and t are expressions containing the
+following constants:
+
+
+
‘dar’
+
The input display aspect ratio, it is the same as (w / h) * sar.
+
+
+
‘hsub’
+
‘vsub’
+
horizontal and vertical chroma subsample values. For example for the
+pixel format "yuv422p" hsub is 2 and vsub is 1.
+
+
+
‘in_h, ih’
+
‘in_w, iw’
+
The input grid cell width and height.
+
+
+
‘sar’
+
The input sample aspect ratio.
+
+
+
‘x’
+
‘y’
+
The x and y coordinates of some point of grid intersection (meant to configure offset).
+
+
+
‘w’
+
‘h’
+
The width and height of the drawn cell.
+
+
+
‘t’
+
The thickness of the drawn cell.
+
+
These constants allow the x, y, w, h and t expressions to refer to
+each other, so you may for example specify y=x/dar or h=w/dar.
+
The description of the accepted parameters follows.
+
+
+
‘box’
+
Used to draw a box around text using background color.
+Value should be either 1 (enable) or 0 (disable).
+The default value of box is 0.
+
+
+
‘boxcolor’
+
The color to be used for drawing box around text. For the syntax of this
+option, check the "Color" section in the ffmpeg-utils manual.
+
+
The default value of boxcolor is "white".
+
+
+
‘expansion’
+
Select how the text is expanded. Can be either none,
+strftime (deprecated) or
+normal (default). See the Text expansion section
+below for details.
+
+
+
‘fix_bounds’
+
If true, check and fix text coords to avoid clipping.
+
+
+
‘fontcolor’
+
The color to be used for drawing fonts. For the syntax of this option, check
+the "Color" section in the ffmpeg-utils manual.
+
+
The default value of fontcolor is "black".
+
+
+
‘fontfile’
+
The font file to be used for drawing text. Path must be included.
+This parameter is mandatory.
+
+
+
‘fontsize’
+
The font size to be used for drawing text.
+The default value of fontsize is 16.
+
+
+
‘ft_load_flags’
+
Flags to be used for loading the fonts.
+
+
The flags map the corresponding flags supported by libfreetype, and are
+a combination of the following values:
+
+
default
+
no_scale
+
no_hinting
+
render
+
no_bitmap
+
vertical_layout
+
force_autohint
+
crop_bitmap
+
pedantic
+
ignore_global_advance_width
+
no_recurse
+
ignore_transform
+
monochrome
+
linear_design
+
no_autohint
+
+
+
Default value is "render".
+
+
For more information consult the documentation for the FT_LOAD_*
+libfreetype flags.
+
+
+
‘shadowcolor’
+
The color to be used for drawing a shadow behind the drawn text. For the
+syntax of this option, check the "Color" section in the ffmpeg-utils manual.
+
+
The default value of shadowcolor is "black".
+
+
+
‘shadowx’
+
‘shadowy’
+
The x and y offsets for the text shadow position with respect to the
+position of the text. They can be either positive or negative
+values. Default value for both is "0".
+
+
+
‘start_number’
+
The starting frame number for the n/frame_num variable. The default value
+is "0".
+
+
+
‘tabsize’
+
The size in number of spaces to use for rendering the tab.
+Default value is 4.
+
+
+
‘timecode’
+
Set the initial timecode representation in "hh:mm:ss[:;.]ff"
+format. It can be used with or without text parameter. timecode_rate
+option must be specified.
+
+
+
‘timecode_rate, rate, r’
+
Set the timecode frame rate (timecode only).
+
+
+
‘text’
+
The text string to be drawn. The text must be a sequence of UTF-8
+encoded characters.
+This parameter is mandatory if no file is specified with the parameter
+textfile.
+
+
+
‘textfile’
+
A text file containing text to be drawn. The text must be a sequence
+of UTF-8 encoded characters.
+
+
This parameter is mandatory if no text string is specified with the
+parameter text.
+
+
If both text and textfile are specified, an error is thrown.
+
+
+
‘reload’
+
If set to 1, the textfile will be reloaded before each frame.
+Be sure to update it atomically, or it may be read partially, or even fail.
+
+
+
‘x’
+
‘y’
+
The expressions which specify the offsets where text will be drawn
+within the video frame. They are relative to the top/left border of the
+output image.
+
+
The default value of x and y is "0".
+
+
See below for the list of accepted constants and functions.
+
+
+
+
The parameters for x and y are expressions containing the
+following constants and functions:
+
+
+
‘dar’
+
input display aspect ratio, it is the same as (w / h) * sar
+
+
+
‘hsub’
+
‘vsub’
+
horizontal and vertical chroma subsample values. For example for the
+pixel format "yuv422p" hsub is 2 and vsub is 1.
+
+
+
‘line_h, lh’
+
the height of each text line
+
+
+
‘main_h, h, H’
+
the input height
+
+
+
‘main_w, w, W’
+
the input width
+
+
+
‘max_glyph_a, ascent’
+
the maximum distance from the baseline to the highest/upper grid
+coordinate used to place a glyph outline point, for all the rendered
+glyphs.
+It is a positive value, due to the grid’s orientation with the Y axis
+upwards.
+
+
+
‘max_glyph_d, descent’
+
the maximum distance from the baseline to the lowest grid coordinate
+used to place a glyph outline point, for all the rendered glyphs.
+This is a negative value, due to the grid’s orientation, with the Y axis
+upwards.
+
+
+
‘max_glyph_h’
+
maximum glyph height, that is the maximum height for all the glyphs
+contained in the rendered text, it is equivalent to ascent -
+descent.
+
+
+
‘max_glyph_w’
+
maximum glyph width, that is the maximum width for all the glyphs
+contained in the rendered text
+
+
+
‘n’
+
the number of input frame, starting from 0
+
+
+
‘rand(min, max)’
+
return a random number included between min and max
+
+
+
‘sar’
+
input sample aspect ratio
+
+
+
‘t’
+
timestamp expressed in seconds, NAN if the input timestamp is unknown
+
+
+
‘text_h, th’
+
the height of the rendered text
+
+
+
‘text_w, tw’
+
the width of the rendered text
+
+
+
‘x’
+
‘y’
+
the x and y offset coordinates where the text is drawn.
+
+
These parameters allow the x and y expressions to refer
+each other, so you can for example specify y=x/dar.
+
+
+
+
If libavfilter was built with --enable-fontconfig, then
+‘fontfile’ can be a fontconfig pattern or omitted.
+
If ‘expansion’ is set to strftime,
+the filter recognizes strftime() sequences in the provided text and
+expands them accordingly. Check the documentation of strftime(). This
+feature is deprecated.
+
+
If ‘expansion’ is set to none, the text is printed verbatim.
+
+
If ‘expansion’ is set to normal (which is the default),
+the following expansion mechanism is used.
+
+
The backslash character ’\’, followed by any character, always expands to
+the second character.
+
+
Sequence of the form %{...} are expanded. The text between the
+braces is a function name, possibly followed by arguments separated by ’:’.
+If the arguments contain special characters or delimiters (’:’ or ’}’),
+they should be escaped.
+
+
Note that they probably must also be escaped as the value for the
+‘text’ option in the filter argument string and as the filter
+argument in the filtergraph description, and possibly also for the shell,
+that makes up to four levels of escaping; using a text file avoids these
+problems.
+
+
The following functions are available:
+
+
+
expr, e
+
The expression evaluation result.
+
+
It must take one argument specifying the expression to be evaluated,
+which accepts the same constants and functions as the x and
+y values. Note that not all constants should be used, for
+example the text size is not known when evaluating the expression, so
+the constants text_w and text_h will have an undefined
+value.
+
+
+
gmtime
+
The time at which the filter is running, expressed in UTC.
+It can accept an argument: a strftime() format string.
+
+
+
localtime
+
The time at which the filter is running, expressed in the local time zone.
+It can accept an argument: a strftime() format string.
+
+
+
metadata
+
Frame metadata. It must take one argument specifying metadata key.
+
+
+
n, frame_num
+
The frame number, starting from 0.
+
+
+
pict_type
+
A 1 character description of the current picture type.
+
+
+
pts
+
The timestamp of the current frame, in seconds, with microsecond accuracy.
+
+Draw ’Test Text’ with font FreeSerif of size 24 at position x=100
+and y=50 (counting from the top-left corner of the screen), text is
+yellow with a red box around it. Both the text and the box have an
+opacity of 20%.
+
+
+Show a text line sliding from right to left in the last row of the video
+frame. The file ‘LONG_LINE’ is assumed to contain a single line
+with no newlines.
+
Detect and draw edges. The filter uses the Canny Edge Detection algorithm.
+
+
The filter accepts the following options:
+
+
+
‘low’
+
‘high’
+
Set low and high threshold values used by the Canny thresholding
+algorithm.
+
+
The high threshold selects the "strong" edge pixels, which are then
+connected through 8-connectivity with the "weak" edge pixels selected
+by the low threshold.
+
+
low and high threshold values must be choosen in the range
+[0,1], and low should be lesser or equal to high.
+
+
Default value for low is 20/255, and default value for high
+is 50/255.
+
The effect type – can be either "in" for fade-in, or "out" for a fade-out
+effect.
+Default is in.
+
+
+
‘start_frame, s’
+
Specify the number of the start frame for starting to apply the fade
+effect. Default is 0.
+
+
+
‘nb_frames, n’
+
The number of frames for which the fade effect has to last. At the end of the
+fade-in effect the output video will have the same intensity as the input video,
+at the end of the fade-out transition the output video will be completely black.
+Default is 25.
+
+
+
‘alpha’
+
If set to 1, fade only alpha channel, if one exists on the input.
+Default value is 0.
+
+
+
‘start_time, st’
+
Specify the timestamp (in seconds) of the frame to start to apply the fade
+effect. If both start_frame and start_time are specified, the fade will start at
+whichever comes last. Default is 0.
+
+
+
‘duration, d’
+
The number of seconds for which the fade effect has to last. At the end of the
+fade-in effect the output video will have the same intensity as the input video,
+at the end of the fade-out transition the output video will be completely black.
+If both duration and nb_frames are specified, duration is used. Default is 0.
+
Field matching filter for inverse telecine. It is meant to reconstruct the
+progressive frames from a telecined stream. The filter does not drop duplicated
+frames, so to achieve a complete inverse telecine fieldmatch needs to be
+followed by a decimation filter such as decimate in the filtergraph.
+
+
The separation of the field matching and the decimation is notably motivated by
+the possibility of inserting a de-interlacing filter fallback between the two.
+If the source has mixed telecined and real interlaced content,
+fieldmatch will not be able to match fields for the interlaced parts.
+But these remaining combed frames will be marked as interlaced, and thus can be
+de-interlaced by a later filter such as yadif before decimation.
+
+
In addition to the various configuration options, fieldmatch can take an
+optional second stream, activated through the ‘ppsrc’ option. If
+enabled, the frames reconstruction will be based on the fields and frames from
+this second stream. This allows the first input to be pre-processed in order to
+help the various algorithms of the filter, while keeping the output lossless
+(assuming the fields are matched properly). Typically, a field-aware denoiser,
+or brightness/contrast adjustments can help.
+
+
Note that this filter uses the same algorithms as TIVTC/TFM (AviSynth project)
+and VIVTC/VFM (VapourSynth project). The later is a light clone of TFM from
+which fieldmatch is based on. While the semantic and usage are very
+close, some behaviour and options names can differ.
+
+
The filter accepts the following options:
+
+
+
‘order’
+
Specify the assumed field order of the input stream. Available values are:
+
+
+
‘auto’
+
Auto detect parity (use FFmpeg’s internal parity value).
+
+
‘bff’
+
Assume bottom field first.
+
+
‘tff’
+
Assume top field first.
+
+
+
+
Note that it is sometimes recommended not to trust the parity announced by the
+stream.
+
+
Default value is auto.
+
+
+
‘mode’
+
Set the matching mode or strategy to use. ‘pc’ mode is the safest in the
+sense that it won’t risk creating jerkiness due to duplicate frames when
+possible, but if there are bad edits or blended fields it will end up
+outputting combed frames when a good match might actually exist. On the other
+hand, ‘pcn_ub’ mode is the most risky in terms of creating jerkiness,
+but will almost always find a good frame if there is one. The other values are
+all somewhere in between ‘pc’ and ‘pcn_ub’ in terms of risking
+jerkiness and creating duplicate frames versus finding good matches in sections
+with bad edits, orphaned fields, blended fields, etc.
+
+
More details about p/c/n/u/b are available in p/c/n/u/b meaning section.
+
+
Available values are:
+
+
+
‘pc’
+
2-way matching (p/c)
+
+
‘pc_n’
+
2-way matching, and trying 3rd match if still combed (p/c + n)
+
+
‘pc_u’
+
2-way matching, and trying 3rd match (same order) if still combed (p/c + u)
+
+
‘pc_n_ub’
+
2-way matching, trying 3rd match if still combed, and trying 4th/5th matches if
+still combed (p/c + n + u/b)
+
+
‘pcn’
+
3-way matching (p/c/n)
+
+
‘pcn_ub’
+
3-way matching, and trying 4th/5th matches if all 3 of the original matches are
+detected as combed (p/c/n + u/b)
+
+
+
+
The parenthesis at the end indicate the matches that would be used for that
+mode assuming ‘order’=tff (and ‘field’ on auto or
+top).
+
+
In terms of speed ‘pc’ mode is by far the fastest and ‘pcn_ub’ is
+the slowest.
+
+
Default value is pc_n.
+
+
+
‘ppsrc’
+
Mark the main input stream as a pre-processed input, and enable the secondary
+input stream as the clean source to pick the fields from. See the filter
+introduction for more details. It is similar to the ‘clip2’ feature from
+VFM/TFM.
+
+
Default value is 0 (disabled).
+
+
+
‘field’
+
Set the field to match from. It is recommended to set this to the same value as
+‘order’ unless you experience matching failures with that setting. In
+certain circumstances changing the field that is used to match from can have a
+large impact on matching performance. Available values are:
+
+
+
‘auto’
+
Automatic (same value as ‘order’).
+
+
‘bottom’
+
Match from the bottom field.
+
+
‘top’
+
Match from the top field.
+
+
+
+
Default value is auto.
+
+
+
‘mchroma’
+
Set whether or not chroma is included during the match comparisons. In most
+cases it is recommended to leave this enabled. You should set this to 0
+only if your clip has bad chroma problems such as heavy rainbowing or other
+artifacts. Setting this to 0 could also be used to speed things up at
+the cost of some accuracy.
+
+
Default value is 1.
+
+
+
‘y0’
+
‘y1’
+
These define an exclusion band which excludes the lines between ‘y0’ and
+‘y1’ from being included in the field matching decision. An exclusion
+band can be used to ignore subtitles, a logo, or other things that may
+interfere with the matching. ‘y0’ sets the starting scan line and
+‘y1’ sets the ending line; all lines in between ‘y0’ and
+‘y1’ (including ‘y0’ and ‘y1’) will be ignored. Setting
+‘y0’ and ‘y1’ to the same value will disable the feature.
+‘y0’ and ‘y1’ defaults to 0.
+
+
+
‘scthresh’
+
Set the scene change detection threshold as a percentage of maximum change on
+the luma plane. Good values are in the [8.0, 14.0] range. Scene change
+detection is only relevant in case ‘combmatch’=sc. The range for
+‘scthresh’ is [0.0, 100.0].
+
+
Default value is 12.0.
+
+
+
‘combmatch’
+
When ‘combatch’ is not none, fieldmatch will take into
+account the combed scores of matches when deciding what match to use as the
+final match. Available values are:
+
+
+
‘none’
+
No final matching based on combed scores.
+
+
‘sc’
+
Combed scores are only used when a scene change is detected.
+
+
‘full’
+
Use combed scores all the time.
+
+
+
+
Default is sc.
+
+
+
‘combdbg’
+
Force fieldmatch to calculate the combed metrics for certain matches and
+print them. This setting is known as ‘micout’ in TFM/VFM vocabulary.
+Available values are:
+
+
+
‘none’
+
No forced calculation.
+
+
‘pcn’
+
Force p/c/n calculations.
+
+
‘pcnub’
+
Force p/c/n/u/b calculations.
+
+
+
+
Default value is none.
+
+
+
‘cthresh’
+
This is the area combing threshold used for combed frame detection. This
+essentially controls how "strong" or "visible" combing must be to be detected.
+Larger values mean combing must be more visible and smaller values mean combing
+can be less visible or strong and still be detected. Valid settings are from
+-1 (every pixel will be detected as combed) to 255 (no pixel will
+be detected as combed). This is basically a pixel difference value. A good
+range is [8, 12].
+
+
Default value is 9.
+
+
+
‘chroma’
+
Sets whether or not chroma is considered in the combed frame decision. Only
+disable this if your source has chroma problems (rainbowing, etc.) that are
+causing problems for the combed frame detection with chroma enabled. Actually,
+using ‘chroma’=0 is usually more reliable, except for the case
+where there is chroma only combing in the source.
+
+
Default value is 0.
+
+
+
‘blockx’
+
‘blocky’
+
Respectively set the x-axis and y-axis size of the window used during combed
+frame detection. This has to do with the size of the area in which
+‘combpel’ pixels are required to be detected as combed for a frame to be
+declared combed. See the ‘combpel’ parameter description for more info.
+Possible values are any number that is a power of 2 starting at 4 and going up
+to 512.
+
+
Default value is 16.
+
+
+
‘combpel’
+
The number of combed pixels inside any of the ‘blocky’ by
+‘blockx’ size blocks on the frame for the frame to be detected as
+combed. While ‘cthresh’ controls how "visible" the combing must be, this
+setting controls "how much" combing there must be in any localized area (a
+window defined by the ‘blockx’ and ‘blocky’ settings) on the
+frame. Minimum value is 0 and maximum is blocky x blockx (at
+which point no frames will ever be detected as combed). This setting is known
+as ‘MI’ in TFM/VFM vocabulary.
+
The numbers correspond to the progressive frame the fields relate to. Here, the
+first two frames are progressive, the 3rd and 4th are combed, and so on.
+
+
When fieldmatch is configured to run a matching from bottom
+(‘field’=bottom) this is how this input stream get transformed:
+
+
Input stream:
+ T 1 2 2 3 4
+ B 1 2 3 4 4 <-- matching reference
+
+Matches: c c n n c
+
+Output stream:
+ T 1 2 3 4 4
+ B 1 2 3 4 4
+
+
+
As a result of the field matching, we can see that some frames get duplicated.
+To perform a complete inverse telecine, you need to rely on a decimation filter
+after this operation. See for instance the decimate filter.
+
+
The same operation now matching from top fields (‘field’=top)
+looks like this:
+
+
Input stream:
+ T 1 2 2 3 4 <-- matching reference
+ B 1 2 3 4 4
+
+Matches: c c p p c
+
+Output stream:
+ T 1 2 2 3 4
+ B 1 2 2 3 4
+
+
+
In these examples, we can see what p, c and n mean;
+basically, they refer to the frame and field of the opposite parity:
+
+
+
p matches the field of the opposite parity in the previous frame
+
c matches the field of the opposite parity in the current frame
+
n matches the field of the opposite parity in the next frame
+
The u and b matching are a bit special in the sense that they match
+from the opposite parity flag. In the following examples, we assume that we are
+currently matching the 2nd frame (Top:2, bottom:2). According to the match, a
+’x’ is placed above and below each matched fields.
+
+
With bottom matching (‘field’=bottom):
+
Match: c p n b u
+
+ x x x x x
+ Top 1 2 2 1 2 2 1 2 2 1 2 2 1 2 2
+ Bottom 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3
+ x x x x x
+
+Output frames:
+ 2 1 2 2 2
+ 2 2 2 1 3
+
+
+
With top matching (‘field’=top):
+
Match: c p n b u
+
+ x x x x x
+ Top 1 2 2 1 2 2 1 2 2 1 2 2 1 2 2
+ Bottom 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3
+ x x x x x
+
+Output frames:
+ 2 2 2 1 2
+ 2 1 3 2 2
+
Output field order. Valid values are tff for top field first or bff
+for bottom field first.
+
+
+
+
Default value is ‘tff’.
+
+
Transformation is achieved by shifting the picture content up or down
+by one line, and filling the remaining line with appropriate picture content.
+This method is consistent with most broadcast field order converters.
+
+
If the input video is not flagged as being interlaced, or it is already
+flagged as being of the required output field order then this filter does
+not alter the incoming video.
+
+
This filter is very useful when converting to or from PAL DV material,
+which is bottom field first.
+
Convert the input video to one of the specified pixel formats.
+Libavfilter will try to pick one that is supported for the input to
+the next filter.
+
+
This filter accepts the following parameters:
+
+
‘pix_fmts’
+
A ’|’-separated list of pixel format names, for example
+"pix_fmts=yuv420p|monow|rgb24".
+
Convert the video to specified constant frame rate by duplicating or dropping
+frames as necessary.
+
+
This filter accepts the following named parameters:
+
+
‘fps’
+
Desired output frame rate. The default is 25.
+
+
+
‘round’
+
Rounding method.
+
+
Possible values are:
+
+
‘zero’
+
zero round towards 0
+
+
‘inf’
+
round away from 0
+
+
‘down’
+
round towards -infinity
+
+
‘up’
+
round towards +infinity
+
+
‘near’
+
round to nearest
+
+
+
The default is near.
+
+
+
‘start_time’
+
Assume the first PTS should be the given value, in seconds. This allows for
+padding/trimming at the start of stream. By default, no assumption is made
+about the first frame’s expected PTS, so no padding or trimming is done.
+For example, this could be set to 0 to pad the beginning with duplicates of
+the first frame if a video stream starts after the audio stream or to trim any
+frames with a negative PTS.
+
+
+
+
+
Alternatively, the options can be specified as a flat string:
+fps[:round].
+
To enable compilation of this filter you need to install the frei0r
+header and configure FFmpeg with --enable-frei0r.
+
+
This filter accepts the following options:
+
+
+
‘filter_name’
+
The name to the frei0r effect to load. If the environment variable
+FREI0R_PATH is defined, the frei0r effect is searched in each one of the
+directories specified by the colon separated list in FREIOR_PATH,
+otherwise in the standard frei0r paths, which are in this order:
+‘HOME/.frei0r-1/lib/’, ‘/usr/local/lib/frei0r-1/’,
+‘/usr/lib/frei0r-1/’.
+
+
+
‘filter_params’
+
A ’|’-separated list of parameters to pass to the frei0r effect.
+
+
+
+
+
A frei0r effect parameter can be a boolean (whose values are specified
+with "y" and "n"), a double, a color (specified by the syntax
+R/G/B, (R, G, and B being float
+numbers from 0.0 to 1.0) or by a color description specified in the "Color"
+section in the ffmpeg-utils manual), a position (specified by the syntax X/Y,
+X and Y being float numbers) and a string.
+
+
The number and kind of parameters depend on the loaded effect. If an
+effect parameter is not specified the default value is set.
+
The colorspace is selected according to the specified options. If one
+of the ‘lum_expr’, ‘cb_expr’, or ‘cr_expr’
+options is specified, the filter will automatically select a YCbCr
+colorspace. If one of the ‘red_expr’, ‘green_expr’, or
+‘blue_expr’ options is specified, it will select an RGB
+colorspace.
+
+
If one of the chrominance expression is not defined, it falls back on the other
+one. If no alpha expression is specified it will evaluate to opaque value.
+If none of chrominance expressions are specified, they will evaluate
+to the luminance expression.
+
+
The expressions can use the following variables and functions:
+
+
+
‘N’
+
The sequential number of the filtered frame, starting from 0.
+
+
+
‘X’
+
‘Y’
+
The coordinates of the current sample.
+
+
+
‘W’
+
‘H’
+
The width and height of the image.
+
+
+
‘SW’
+
‘SH’
+
Width and height scale depending on the currently filtered plane. It is the
+ratio between the corresponding luma plane number of pixels and the current
+plane ones. E.g. for YUV4:2:0 the values are 1,1 for the luma plane, and
+0.5,0.5 for chroma planes.
+
+
+
‘T’
+
Time of the current frame, expressed in seconds.
+
+
+
‘p(x, y)’
+
Return the value of the pixel at location (x,y) of the current
+plane.
+
+
+
‘lum(x, y)’
+
Return the value of the pixel at location (x,y) of the luminance
+plane.
+
+
+
‘cb(x, y)’
+
Return the value of the pixel at location (x,y) of the
+blue-difference chroma plane. Return 0 if there is no such plane.
+
+
+
‘cr(x, y)’
+
Return the value of the pixel at location (x,y) of the
+red-difference chroma plane. Return 0 if there is no such plane.
+
+
+
‘r(x, y)’
+
‘g(x, y)’
+
‘b(x, y)’
+
Return the value of the pixel at location (x,y) of the
+red/green/blue component. Return 0 if there is no such component.
+
+
+
‘alpha(x, y)’
+
Return the value of the pixel at location (x,y) of the alpha
+plane. Return 0 if there is no such plane.
+
+
+
+
For functions, if x and y are outside the area, the value will be
+automatically clipped to the closer edge.
+
Fix the banding artifacts that are sometimes introduced into nearly flat
+regions by truncation to 8bit color depth.
+Interpolate the gradients that should go where the bands are, and
+dither them.
+
+
This filter is designed for playback only. Do not use it prior to
+lossy compression, because compression tends to lose the dither and
+bring back the bands.
+
+
This filter accepts the following options:
+
+
+
‘strength’
+
The maximum amount by which the filter will change any one pixel. Also the
+threshold for detecting nearly flat regions. Acceptable values range from .51 to
+64, default value is 1.2, out-of-range values will be clipped to the valid
+range.
+
+
+
‘radius’
+
The neighborhood to fit the gradient to. A larger radius makes for smoother
+gradients, but also prevents the filter from modifying the pixels near detailed
+regions. Acceptable values are 8-32, default value is 16, out-of-range values
+will be clipped to the valid range.
+
+
+
+
+
Alternatively, the options can be specified as a flat string:
+strength[:radius]
+
First input is the video stream to process, and second one is the Hald CLUT.
+The Hald CLUT input can be a simple picture or a complete video stream.
+
+
The filter accepts the following options:
+
+
+
‘shortest’
+
Force termination when the shortest input terminates. Default is 0.
+
+
‘repeatlast’
+
Continue applying the last CLUT after the end of the stream. A value of
+0 disable the filter after the last frame of the CLUT is reached.
+Default is 1.
+
+
+
+
haldclut also has the same interpolation options as lut3d (both
+filters share the same internals).
+
The Hald CLUT will be applied to the 10 first seconds (duration of
+‘clut.nut’), then the latest picture of that CLUT stream will be applied
+to the remaining frames of the mandelbrot stream.
+
A Hald CLUT is supposed to be a squared image of Level*Level*Level by
+Level*Level*Level pixels. For a given Hald CLUT, FFmpeg will select the
+biggest possible square starting at the top left of the picture. The remaining
+padding pixels (bottom or right) will be ignored. This area can be used to add
+a preview of the Hald CLUT.
+
+
Typically, the following generated Hald CLUT will be supported by the
+haldclut filter:
+
It contains the original and a preview of the effect of the CLUT: SMPTE color
+bars are displayed on the right-top, and below the same color bars processed by
+the color changes.
+
+
Then, the effect of this Hald CLUT can be visualized with:
+
This filter applies a global color histogram equalization on a
+per-frame basis.
+
+
It can be used to correct video that has a compressed range of pixel
+intensities. The filter redistributes the pixel intensities to
+equalize their distribution across the intensity range. It may be
+viewed as an "automatically adjusting contrast filter". This filter is
+useful only for correcting degraded or poorly captured source
+video.
+
+
The filter accepts the following options:
+
+
+
‘strength’
+
Determine the amount of equalization to be applied. As the strength
+is reduced, the distribution of pixel intensities more-and-more
+approaches that of the input frame. The value must be a float number
+in the range [0,1] and defaults to 0.200.
+
+
+
‘intensity’
+
Set the maximum intensity that can generated and scale the output
+values appropriately. The strength should be set as desired and then
+the intensity can be limited if needed to avoid washing-out. The value
+must be a float number in the range [0,1] and defaults to 0.210.
+
+
+
‘antibanding’
+
Set the antibanding level. If enabled the filter will randomly vary
+the luminance of output pixels by a small amount to avoid banding of
+the histogram. Possible values are none, weak or
+strong. It defaults to none.
+
Compute and draw a color distribution histogram for the input video.
+
+
The computed histogram is a representation of distribution of color components
+in an image.
+
+
The filter accepts the following options:
+
+
+
‘mode’
+
Set histogram mode.
+
+
It accepts the following values:
+
+
‘levels’
+
standard histogram that display color components distribution in an image.
+Displays color graph for each color component. Shows distribution
+of the Y, U, V, A or R, G, B components, depending on input format,
+in current frame. Bellow each graph is color component scale meter.
+
+
+
‘color’
+
chroma values in vectorscope, if brighter more such chroma values are
+distributed in an image.
+Displays chroma values (U/V color placement) in two dimensional graph
+(which is called a vectorscope). It can be used to read of the hue and
+saturation of the current frame. At a same time it is a histogram.
+The whiter a pixel in the vectorscope, the more pixels of the input frame
+correspond to that pixel (that is the more pixels have this chroma value).
+The V component is displayed on the horizontal (X) axis, with the leftmost
+side being V = 0 and the rightmost side being V = 255.
+The U component is displayed on the vertical (Y) axis, with the top
+representing U = 0 and the bottom representing U = 255.
+
+
The position of a white pixel in the graph corresponds to the chroma value
+of a pixel of the input clip. So the graph can be used to read of the
+hue (color flavor) and the saturation (the dominance of the hue in the color).
+As the hue of a color changes, it moves around the square. At the center of
+the square, the saturation is zero, which means that the corresponding pixel
+has no color. If you increase the amount of a specific color, while leaving
+the other colors unchanged, the saturation increases, and you move towards
+the edge of the square.
+
+
+
‘color2’
+
chroma values in vectorscope, similar as color but actual chroma values
+are displayed.
+
+
+
‘waveform’
+
per row/column color component graph. In row mode graph in the left side represents
+color component value 0 and right side represents value = 255. In column mode top
+side represents color component value = 0 and bottom side represents value = 255.
+
+
+
Default value is levels.
+
+
+
‘level_height’
+
Set height of level in levels. Default value is 200.
+Allowed range is [50, 2048].
+
+
+
‘scale_height’
+
Set height of color scale in levels. Default value is 12.
+Allowed range is [0, 40].
+
+
+
‘step’
+
Set step for waveform mode. Smaller values are useful to find out how much
+of same luminance values across input rows/columns are distributed.
+Default value is 10. Allowed range is [1, 255].
+
+
+
‘waveform_mode’
+
Set mode for waveform. Can be either row, or column.
+Default is row.
+
+
+
‘waveform_mirror’
+
Set mirroring mode for waveform. 0 means unmirrored, 1
+means mirrored. In mirrored mode, higher values will be represented on the left
+side for row mode and at the top for column mode. Default is
+0 (unmirrored).
+
+
+
‘display_mode’
+
Set display mode for waveform and levels.
+It accepts the following values:
+
+
‘parade’
+
Display separate graph for the color components side by side in
+row waveform mode or one below other in column waveform mode
+for waveform histogram mode. For levels histogram mode
+per color component graphs are placed one bellow other.
+
+
This display mode in waveform histogram mode makes it easy to spot
+color casts in the highlights and shadows of an image, by comparing the
+contours of the top and the bottom of each waveform.
+Since whites, grays, and blacks are characterized by
+exactly equal amounts of red, green, and blue, neutral areas of the
+picture should display three waveforms of roughly equal width/height.
+If not, the correction is easy to make by making adjustments to level the
+three waveforms.
+
+
+
‘overlay’
+
Presents information that’s identical to that in the parade, except
+that the graphs representing color components are superimposed directly
+over one another.
+
+
This display mode in waveform histogram mode can make it easier to spot
+the relative differences or similarities in overlapping areas of the color
+components that are supposed to be identical, such as neutral whites, grays,
+or blacks.
+
+
+
Default is parade.
+
+
+
‘levels_mode’
+
Set mode for levels. Can be either linear, or logarithmic.
+Default is linear.
+
High precision/quality 3d denoise filter. This filter aims to reduce
+image noise producing smooth images and making still images really
+still. It should enhance compressibility.
+
+
It accepts the following optional parameters:
+
+
+
‘luma_spatial’
+
a non-negative float number which specifies spatial luma strength,
+defaults to 4.0
+
+
+
‘chroma_spatial’
+
a non-negative float number which specifies spatial chroma strength,
+defaults to 3.0*luma_spatial/4.0
+
+
+
‘luma_tmp’
+
a float number which specifies luma temporal strength, defaults to
+6.0*luma_spatial/4.0
+
+
+
‘chroma_tmp’
+
a float number which specifies chroma temporal strength, defaults to
+luma_tmp*chroma_spatial/luma_spatial
+
This filter allows to process interlaced images fields without
+deinterlacing them. Deinterleaving splits the input frame into 2
+fields (so called half pictures). Odd lines are moved to the top
+half of the output image, even lines to the bottom half.
+You can process (filter) them independently and then re-interleave them.
+
+
The filter accepts the following options:
+
+
+
‘luma_mode, l’
+
‘chroma_mode, c’
+
‘alpha_mode, a’
+
Available values for luma_mode, chroma_mode and
+alpha_mode are:
+
+
+
‘none’
+
Do nothing.
+
+
+
‘deinterleave, d’
+
Deinterleave fields, placing one above the other.
+
+
+
‘interleave, i’
+
Interleave fields. Reverse the effect of deinterleaving.
+
+
+
Default value is none.
+
+
+
‘luma_swap, ls’
+
‘chroma_swap, cs’
+
‘alpha_swap, as’
+
Swap luma/chroma/alpha fields. Exchange even & odd lines. Default value is 0.
+
Simple interlacing filter from progressive contents. This interleaves upper (or
+lower) lines from odd frames with lower (or upper) lines from even frames,
+halving the frame rate and preserving image height.
+
+
Original Original New Frame
+ Frame 'j' Frame 'j+1' (tff)
+ ========== =========== ==================
+ Line 0 --------------------> Frame 'j' Line 0
+ Line 1 Line 1 ----> Frame 'j+1' Line 1
+ Line 2 ---------------------> Frame 'j' Line 2
+ Line 3 Line 3 ----> Frame 'j+1' Line 3
+ ... ... ...
+New Frame + 1 will be generated by Frame 'j+2' and Frame 'j+3' and so on
+
+
+
It accepts the following optional parameters:
+
+
+
‘scan’
+
determines whether the interlaced frame is taken from the even (tff - default)
+or odd (bff) lines of the progressive frame.
+
+
+
‘lowpass’
+
Enable (default) or disable the vertical lowpass filter to avoid twitter
+interlacing and reduce moire patterns.
+
Deinterlace input video by applying Donald Graft’s adaptive kernel
+deinterling. Work on interlaced parts of a video to produce
+progressive frames.
+
+
The description of the accepted parameters follows.
+
+
+
‘thresh’
+
Set the threshold which affects the filter’s tolerance when
+determining if a pixel line must be processed. It must be an integer
+in the range [0,255] and defaults to 10. A value of 0 will result in
+applying the process on every pixels.
+
+
+
‘map’
+
Paint pixels exceeding the threshold value to white if set to 1.
+Default is 0.
+
+
+
‘order’
+
Set the fields order. Swap fields if set to 1, leave fields alone if
+0. Default is 0.
+
+
+
‘sharp’
+
Enable additional sharpening if set to 1. Default is 0.
+
+
+
‘twoway’
+
Enable twoway sharpening if set to 1. Default is 0.
+
Compute a look-up table for binding each pixel component input value
+to an output value, and apply it to input video.
+
+
lutyuv applies a lookup table to a YUV input video, lutrgb
+to an RGB input video.
+
+
These filters accept the following options:
+
+
‘c0’
+
set first pixel component expression
+
+
‘c1’
+
set second pixel component expression
+
+
‘c2’
+
set third pixel component expression
+
+
‘c3’
+
set fourth pixel component expression, corresponds to the alpha component
+
+
+
‘r’
+
set red component expression
+
+
‘g’
+
set green component expression
+
+
‘b’
+
set blue component expression
+
+
‘a’
+
alpha component expression
+
+
+
‘y’
+
set Y/luminance component expression
+
+
‘u’
+
set U/Cb component expression
+
+
‘v’
+
set V/Cr component expression
+
+
+
+
Each of them specifies the expression to use for computing the lookup table for
+the corresponding pixel component values.
+
+
The exact component associated to each of the c* options depends on the
+format in input.
+
+
The lut filter requires either YUV or RGB pixel formats in input,
+lutrgb requires RGB pixel formats in input, and lutyuv requires YUV.
+
+
The expressions can contain the following constants and functions:
+
+
+
‘w’
+
‘h’
+
the input width and height
+
+
+
‘val’
+
input value for the pixel component
+
+
+
‘clipval’
+
the input value clipped in the minval-maxval range
+
+
+
‘maxval’
+
maximum value for the pixel component
+
+
+
‘minval’
+
minimum value for the pixel component
+
+
+
‘negval’
+
the negated value for the pixel component value clipped in the
+minval-maxval range , it corresponds to the expression
+"maxval-clipval+minval"
+
+
+
‘clip(val)’
+
the computed value in val clipped in the
+minval-maxval range
+
+
+
‘gammaval(gamma)’
+
the computed gamma correction value of the pixel component value
+clipped in the minval-maxval range, corresponds to the
+expression
+"pow((clipval-minval)/(maxval-minval)\,gamma)*(maxval-minval)+minval"
+
Merge color channel components from several video streams.
+
+
The filter accepts up to 4 input streams, and merge selected input
+planes to the output video.
+
+
This filter accepts the following options:
+
+
‘mapping’
+
Set input to output plane mapping. Default is 0.
+
+
The mappings is specified as a bitmap. It should be specified as a
+hexadecimal number in the form 0xAa[Bb[Cc[Dd]]]. ’Aa’ describes the
+mapping for the first plane of the output stream. ’A’ sets the number of
+the input stream to use (from 0 to 3), and ’a’ the plane number of the
+corresponding input to use (from 0 to 3). The rest of the mappings is
+similar, ’Bb’ describes the mapping for the output stream second
+plane, ’Cc’ describes the mapping for the output stream third plane and
+’Dd’ describes the mapping for the output stream fourth plane.
+
This filter provides a wrapper around some of the filters of
+MPlayer/MEncoder.
+
+
This wrapper is considered experimental. Some of the wrapped filters
+may not work properly and we may drop support for them, as they will
+be implemented natively into FFmpeg. Thus you should avoid
+depending on them when writing portable scripts.
+
+
The filter accepts the parameters:
+filter_name[:=]filter_params
+
+
filter_name is the name of a supported MPlayer filter,
+filter_params is a string containing the parameters accepted by
+the named filter.
+
+
The list of the currently supported filters follows:
+
+
eq2
+
eq
+
fspp
+
ilpack
+
pp7
+
softpulldown
+
uspp
+
+
+
The parameter syntax and behavior for the listed filters are the same
+of the corresponding MPlayer filters. For detailed instructions check
+the "VIDEO FILTERS" section in the MPlayer manual.
+
Drop frames that do not differ greatly from the previous frame in
+order to reduce frame rate.
+
+
The main use of this filter is for very-low-bitrate encoding
+(e.g. streaming over dialup modem), but it could in theory be used for
+fixing movies that were inverse-telecined incorrectly.
+
+
A description of the accepted options follows.
+
+
+
‘max’
+
Set the maximum number of consecutive frames which can be dropped (if
+positive), or the minimum interval between dropped frames (if
+negative). If the value is 0, the frame is dropped unregarding the
+number of previous sequentially dropped frames.
+
+
Default value is 0.
+
+
+
‘hi’
+
‘lo’
+
‘frac’
+
Set the dropping threshold values.
+
+
Values for ‘hi’ and ‘lo’ are for 8x8 pixel blocks and
+represent actual pixel value differences, so a threshold of 64
+corresponds to 1 unit of difference for each pixel, or the same spread
+out differently over the block.
+
+
A frame is a candidate for dropping if no 8x8 blocks differ by more
+than a threshold of ‘hi’, and if no more than ‘frac’ blocks (1
+meaning the whole image) differ by more than a threshold of ‘lo’.
+
+
Default value for ‘hi’ is 64*12, default value for ‘lo’ is
+64*5, and default value for ‘frac’ is 0.33.
+
Dilate an image by using a specific structuring element.
+This filter corresponds to the libopencv function cvDilate.
+
+
It accepts the parameters: struct_el|nb_iterations.
+
+
struct_el represents a structuring element, and has the syntax:
+colsxrows+anchor_xxanchor_y/shape
+
+
cols and rows represent the number of columns and rows of
+the structuring element, anchor_x and anchor_y the anchor
+point, and shape the shape for the structuring element, and
+can be one of the values "rect", "cross", "ellipse", "custom".
+
+
If the value for shape is "custom", it must be followed by a
+string of the form "=filename". The file with name
+filename is assumed to represent a binary image, with each
+printable character corresponding to a bright pixel. When a custom
+shape is used, cols and rows are ignored, the number
+or columns and rows of the read file are assumed instead.
+
+
The default value for struct_el is "3x3+0x0/rect".
+
+
nb_iterations specifies the number of times the transform is
+applied to the image, and defaults to 1.
+
+
Follow some example:
+
# use the default values
+ocv=dilate
+
+# dilate using a structuring element with a 5x5 cross, iterate two times
+ocv=filter_name=dilate:filter_params=5x5+2x2/cross|2
+
+# read the shape from the file diamond.shape, iterate two times
+# the file diamond.shape may contain a pattern of characters like this:
+# *
+# ***
+# *****
+# ***
+# *
+# the specified cols and rows are ignored (but not the anchor point coordinates)
+ocv=dilate:0x0+2x2/custom=diamond.shape|2
+
The filter takes the following parameters:
+type|param1|param2|param3|param4.
+
+
type is the type of smooth filter to apply, and can be one of
+the following values: "blur", "blur_no_scale", "median", "gaussian",
+"bilateral". The default value is "gaussian".
+
+
param1, param2, param3, and param4 are
+parameters whose meanings depend on smooth type. param1 and
+param2 accept integer positive values or 0, param3 and
+param4 accept float values.
+
+
The default value for param1 is 3, the default value for the
+other parameters is 0.
+
+
These parameters correspond to the parameters assigned to the
+libopencv function cvSmooth.
+
It takes two inputs and one output, the first input is the "main"
+video on which the second input is overlayed.
+
+
This filter accepts the following parameters:
+
+
A description of the accepted options follows.
+
+
+
‘x’
+
‘y’
+
Set the expression for the x and y coordinates of the overlayed video
+on the main video. Default value is "0" for both expressions. In case
+the expression is invalid, it is set to a huge value (meaning that the
+overlay will not be displayed within the output visible area).
+
+
+
‘eval’
+
Set when the expressions for ‘x’, and ‘y’ are evaluated.
+
+
It accepts the following values:
+
+
‘init’
+
only evaluate expressions once during the filter initialization or
+when a command is processed
+
+
+
‘frame’
+
evaluate expressions for each incoming frame
+
+
+
+
Default value is ‘frame’.
+
+
+
‘shortest’
+
If set to 1, force the output to terminate when the shortest input
+terminates. Default value is 0.
+
+
+
‘format’
+
Set the format for the output video.
+
+
It accepts the following values:
+
+
‘yuv420’
+
force YUV420 output
+
+
+
‘yuv444’
+
force YUV444 output
+
+
+
‘rgb’
+
force RGB output
+
+
+
+
Default value is ‘yuv420’.
+
+
+
‘rgb (deprecated)’
+
If set to 1, force the filter to accept inputs in the RGB
+color space. Default value is 0. This option is deprecated, use
+‘format’ instead.
+
+
+
‘repeatlast’
+
If set to 1, force the filter to draw the last overlay frame over the
+main input until the end of the stream. A value of 0 disables this
+behavior. Default value is 1.
+
+
+
+
The ‘x’, and ‘y’ expressions can contain the following
+parameters.
+
+
+
‘main_w, W’
+
‘main_h, H’
+
main input width and height
+
+
+
‘overlay_w, w’
+
‘overlay_h, h’
+
overlay input width and height
+
+
+
‘x’
+
‘y’
+
the computed values for x and y. They are evaluated for
+each new frame.
+
+
+
‘hsub’
+
‘vsub’
+
horizontal and vertical chroma subsample values of the output
+format. For example for the pixel format "yuv422p" hsub is 2 and
+vsub is 1.
+
+
+
‘n’
+
the number of input frame, starting from 0
+
+
+
‘pos’
+
the position in the file of the input frame, NAN if unknown
+
+
+
‘t’
+
timestamp expressed in seconds, NAN if the input timestamp is unknown
+
+
+
+
Note that the n, pos, t variables are available only
+when evaluation is done per frame, and will evaluate to NAN
+when ‘eval’ is set to ‘init’.
+
+
Be aware that frames are taken from each input video in timestamp
+order, hence, if their initial timestamps differ, it is a good idea
+to pass the two inputs through a setpts=PTS-STARTPTS filter to
+have them begin in the same zero timestamp, as it does the example for
+the movie filter.
+
+
You can chain together more overlays but you should test the
+efficiency of such approach.
+
Add paddings to the input image, and place the original input at the
+given coordinates x, y.
+
+
This filter accepts the following parameters:
+
+
+
‘width, w’
+
‘height, h’
+
Specify an expression for the size of the output image with the
+paddings added. If the value for width or height is 0, the
+corresponding input size is used for the output.
+
+
The width expression can reference the value set by the
+height expression, and vice versa.
+
+
The default value of width and height is 0.
+
+
+
‘x’
+
‘y’
+
Specify an expression for the offsets where to place the input image
+in the padded area with respect to the top/left border of the output
+image.
+
+
The x expression can reference the value set by the y
+expression, and vice versa.
+
+
The default value of x and y is 0.
+
+
+
‘color’
+
Specify the color of the padded area. For the syntax of this option,
+check the "Color" section in the ffmpeg-utils manual.
+
+
The default value of color is "black".
+
+
+
+
The value for the width, height, x, and y
+options are expressions containing the following constants:
+
+
+
‘in_w’
+
‘in_h’
+
the input video width and height
+
+
+
‘iw’
+
‘ih’
+
same as in_w and in_h
+
+
+
‘out_w’
+
‘out_h’
+
the output width and height, that is the size of the padded area as
+specified by the width and height expressions
+
+
+
‘ow’
+
‘oh’
+
same as out_w and out_h
+
+
+
‘x’
+
‘y’
+
x and y offsets as specified by the x and y
+expressions, or NAN if not yet specified
+
+
+
‘a’
+
same as iw / ih
+
+
+
‘sar’
+
input sample aspect ratio
+
+
+
‘dar’
+
input display aspect ratio, it is the same as (iw / ih) * sar
+
+
+
‘hsub’
+
‘vsub’
+
horizontal and vertical chroma subsample values. For example for the
+pixel format "yuv422p" hsub is 2 and vsub is 1.
+
+Add paddings with color "violet" to the input video. Output video
+size is 640x480, the top-left corner of the input video is placed at
+column 0, row 40:
+
pad=640:480:0:40:violet
+
+
+
The example above is equivalent to the following command:
+
pad=width=640:height=480:x=0:y=40:color=violet
+
+
+
+Pad the input to get an output with dimensions increased by 3/2,
+and put the input video at the center of the padded area:
+
pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
+
+
+
+Pad the input to get a squared output with size equal to the maximum
+value between the input width and height, and put the input video at
+the center of the padded area:
+
pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
+
+
+
+Pad the input to get a final w/h ratio of 16:9:
+
pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
+
+
+
+In case of anamorphic video, in order to set the output display aspect
+correctly, it is necessary to use sar in the expression,
+according to the relation:
+
(ih * X / ih) * sar = output_dar
+X = output_dar / sar
+
+
+
Thus the previous example needs to be modified to:
+
pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2"
+
+
+
+Double output size and put the input video in the bottom-right
+corner of the output padded area:
+
Correct perspective of video not recorded perpendicular to the screen.
+
+
A description of the accepted parameters follows.
+
+
+
‘x0’
+
‘y0’
+
‘x1’
+
‘y1’
+
‘x2’
+
‘y2’
+
‘x3’
+
‘y3’
+
Set coordinates expression for top left, top right, bottom left and bottom right corners.
+Default values are 0:0:W:0:0:H:W:H with which perspective will remain unchanged.
+
+
The expressions can use the following variables:
+
Delay interlaced video by one field time so that the field order changes.
+
+
The intended use is to fix PAL movies that have been captured with the
+opposite field order to the film-to-video transfer.
+
+
A description of the accepted parameters follows.
+
+
+
‘mode’
+
Set phase mode.
+
+
It accepts the following values:
+
+
‘t’
+
Capture field order top-first, transfer bottom-first.
+Filter will delay the bottom field.
+
+
+
‘b’
+
Capture field order bottom-first, transfer top-first.
+Filter will delay the top field.
+
+
+
‘p’
+
Capture and transfer with the same field order. This mode only exists
+for the documentation of the other options to refer to, but if you
+actually select it, the filter will faithfully do nothing.
+
+
+
‘a’
+
Capture field order determined automatically by field flags, transfer
+opposite.
+Filter selects among ‘t’ and ‘b’ modes on a frame by frame
+basis using field flags. If no field information is available,
+then this works just like ‘u’.
+
+
+
‘u’
+
Capture unknown or varying, transfer opposite.
+Filter selects among ‘t’ and ‘b’ on a frame by frame basis by
+analyzing the images and selecting the alternative that produces best
+match between the fields.
+
+
+
‘T’
+
Capture top-first, transfer unknown or varying.
+Filter selects among ‘t’ and ‘p’ using image analysis.
+
+
+
‘B’
+
Capture bottom-first, transfer unknown or varying.
+Filter selects among ‘b’ and ‘p’ using image analysis.
+
+
+
‘A’
+
Capture determined by field flags, transfer unknown or varying.
+Filter selects among ‘t’, ‘b’ and ‘p’ using field flags and
+image analysis. If no field information is available, then this works just
+like ‘U’. This is the default mode.
+
+
+
‘U’
+
Both capture and transfer unknown or varying.
+Filter selects among ‘t’, ‘b’ and ‘p’ using image analysis only.
+
Enable the specified chain of postprocessing subfilters using libpostproc. This
+library should be automatically selected with a GPL build (--enable-gpl).
+Subfilters must be separated by ’/’ and can be disabled by prepending a ’-’.
+Each subfilter and some options have a short and a long name that can be used
+interchangeably, i.e. dr/dering are the same.
+
+
The filters accept the following options:
+
+
+
‘subfilters’
+
Set postprocessing subfilters string.
+
+
+
+
All subfilters share common options to determine their scope:
+
+
+
‘a/autoq’
+
Honor the quality commands for this subfilter.
+
+
+
‘c/chrom’
+
Do chrominance filtering, too (default).
+
+
+
‘y/nochrom’
+
Do luminance filtering only (no chrominance).
+
+
+
‘n/noluma’
+
Do chrominance filtering only (no luminance).
+
+
+
+
These options can be appended after the subfilter name, separated by a ’|’.
+
+
Available subfilters are:
+
+
+
‘hb/hdeblock[|difference[|flatness]]’
+
Horizontal deblocking filter
+
+
‘difference’
+
Difference factor where higher values mean more deblocking (default: 32).
+
+
‘flatness’
+
Flatness threshold where lower values mean more deblocking (default: 39).
+
+
+
+
+
‘vb/vdeblock[|difference[|flatness]]’
+
Vertical deblocking filter
+
+
‘difference’
+
Difference factor where higher values mean more deblocking (default: 32).
+
+
‘flatness’
+
Flatness threshold where lower values mean more deblocking (default: 39).
+
+
+
+
+
‘ha/hadeblock[|difference[|flatness]]’
+
Accurate horizontal deblocking filter
+
+
‘difference’
+
Difference factor where higher values mean more deblocking (default: 32).
+
+
‘flatness’
+
Flatness threshold where lower values mean more deblocking (default: 39).
+
+
+
+
+
‘va/vadeblock[|difference[|flatness]]’
+
Accurate vertical deblocking filter
+
+
‘difference’
+
Difference factor where higher values mean more deblocking (default: 32).
+
+
‘flatness’
+
Flatness threshold where lower values mean more deblocking (default: 39).
+
+
+
+
+
+
The horizontal and vertical deblocking filters share the difference and
+flatness values so you cannot set different horizontal and vertical
+thresholds.
+
Obtain the average, maximum and minimum PSNR (Peak Signal to Noise
+Ratio) between two input videos.
+
+
This filter takes in input two input videos, the first input is
+considered the "main" source and is passed unchanged to the
+output. The second input is used as a "reference" video for computing
+the PSNR.
+
+
Both video inputs must have the same resolution and pixel format for
+this filter to work correctly. Also it assumes that both inputs
+have the same number of frames, which are compared one by one.
+
+
The obtained average PSNR is printed through the logging system.
+
+
The filter stores the accumulated MSE (mean squared error) of each
+frame, and at the end of the processing it is averaged across all frames
+equally, and the following formula is applied to obtain the PSNR:
+
+
PSNR = 10*log10(MAX^2/MSE)
+
+
+
Where MAX is the average of the maximum values of each component of the
+image.
+
+
The description of the accepted parameters follows.
+
+
+
‘stats_file, f’
+
If specified the filter will use the named file to save the PSNR of
+each individual frame.
+
+
+
+
The file printed if stats_file is selected, contains a sequence of
+key/value pairs of the form key:value for each compared
+couple of frames.
+
+
A description of each shown parameter follows:
+
+
+
‘n’
+
sequential number of the input frame, starting from 1
+
+
+
‘mse_avg’
+
Mean Square Error pixel-by-pixel average difference of the compared
+frames, averaged over all the image components.
+
+
+
‘mse_y, mse_u, mse_v, mse_r, mse_g, mse_g, mse_a’
+
Mean Square Error pixel-by-pixel average difference of the compared
+frames for the component specified by the suffix.
+
On this example the input file being processed is compared with the
+reference file ‘ref_movie.mpg’. The PSNR of each individual frame
+is stored in ‘stats.log’.
+
Pulldown reversal (inverse telecine) filter, capable of handling mixed
+hard-telecine, 24000/1001 fps progressive, and 30000/1001 fps progressive
+content.
+
+
The pullup filter is designed to take advantage of future context in making
+its decisions. This filter is stateless in the sense that it does not lock
+onto a pattern to follow, but it instead looks forward to the following
+fields in order to identify matches and rebuild progressive frames.
+
+
To produce content with an even framerate, insert the fps filter after
+pullup, use fps=24000/1001 if the input frame rate is 29.97fps,
+fps=24 for 30fps and the (rare) telecined 25fps input.
+
+
The filter accepts the following options:
+
+
+
‘jl’
+
‘jr’
+
‘jt’
+
‘jb’
+
These options set the amount of "junk" to ignore at the left, right, top, and
+bottom of the image, respectively. Left and right are in units of 8 pixels,
+while top and bottom are in units of 2 lines.
+The default is 8 pixels on each side.
+
+
+
‘sb’
+
Set the strict breaks. Setting this option to 1 will reduce the chances of
+filter generating an occasional mismatched frame, but it may also cause an
+excessive number of frames to be dropped during high motion sequences.
+Conversely, setting it to -1 will make filter match fields more easily.
+This may help processing of video where there is slight blurring between
+the fields, but may also cause there to be interlaced frames in the output.
+Default value is 0.
+
+
+
‘mp’
+
Set the metric plane to use. It accepts the following values:
+
+
‘l’
+
Use luma plane.
+
+
+
‘u’
+
Use chroma blue plane.
+
+
+
‘v’
+
Use chroma red plane.
+
+
+
+
This option may be set to use chroma plane instead of the default luma plane
+for doing filter’s computations. This may improve accuracy on very clean
+source material, but more likely will decrease accuracy, especially if there
+is chroma noise (rainbow effect) or any grayscale video.
+The main purpose of setting ‘mp’ to a chroma plane is to reduce CPU
+load and make pullup usable in realtime on slow machines.
+
+
+
+
For best results (without duplicated frames in the output file) it is
+necessary to change the output frame rate. For example, to inverse
+telecine NTSC input:
+
Suppress a TV station logo, using an image file to determine which
+pixels comprise the logo. It works by filling in the pixels that
+comprise the logo with neighboring pixels.
+
+
The filter accepts the following options:
+
+
+
‘filename, f’
+
Set the filter bitmap file, which can be any image format supported by
+libavformat. The width and height of the image file must match those of the
+video stream being processed.
+
+
+
+
Pixels in the provided bitmap image with a value of zero are not
+considered part of the logo, non-zero pixels are considered part of
+the logo. If you use white (255) for the logo and black (0) for the
+rest, you will be safe. For making the filter bitmap, it is
+recommended to take a screen capture of a black frame with the logo
+visible, and then using a threshold filter followed by the erode
+filter once or twice.
+
+
If needed, little splotches can be fixed manually. Remember that if
+logo pixels are not covered, the filter quality will be much
+reduced. Marking too many pixels as part of the logo does not hurt as
+much, but it will increase the amount of blurring needed to cover over
+the image and will destroy more information than necessary, and extra
+pixels will slow things down on a large logo.
+
Rotate video by an arbitrary angle expressed in radians.
+
+
The filter accepts the following options:
+
+
A description of the optional parameters follows.
+
+
‘angle, a’
+
Set an expression for the angle by which to rotate the input video
+clockwise, expressed as a number of radians. A negative value will
+result in a counter-clockwise rotation. By default it is set to "0".
+
+
This expression is evaluated for each frame.
+
+
+
‘out_w, ow’
+
Set the output width expression, default value is "iw".
+This expression is evaluated just once during configuration.
+
+
+
‘out_h, oh’
+
Set the output height expression, default value is "ih".
+This expression is evaluated just once during configuration.
+
+
+
‘bilinear’
+
Enable bilinear interpolation if set to 1, a value of 0 disables
+it. Default value is 1.
+
+
+
‘fillcolor, c’
+
Set the color used to fill the output area not covered by the rotated
+image. For the generalsyntax of this option, check the "Color" section in the
+ffmpeg-utils manual. If the special value "none" is selected then no
+background is printed (useful for example if the background is never shown).
+
+
Default value is "black".
+
+
+
+
The expressions for the angle and the output size can contain the
+following constants and functions:
+
+
+
‘n’
+
sequential number of the input frame, starting from 0. It is always NAN
+before the first frame is filtered.
+
+
+
‘t’
+
time in seconds of the input frame, it is set to 0 when the filter is
+configured. It is always NAN before the first frame is filtered.
+
+
+
‘hsub’
+
‘vsub’
+
horizontal and vertical chroma subsample values. For example for the
+pixel format "yuv422p" hsub is 2 and vsub is 1.
+
+
+
‘in_w, iw’
+
‘in_h, ih’
+
the input video width and heigth
+
+
+
‘out_w, ow’
+
‘out_h, oh’
+
the output width and heigth, that is the size of the padded area as
+specified by the width and height expressions
+
+
+
‘rotw(a)’
+
‘roth(a)’
+
the minimal width/height required for completely containing the input
+video rotated by a radians.
+
+
These are only available when computing the ‘out_w’ and
+‘out_h’ expressions.
+
Set luma blur filter strength, must be a value in range 0.1-4.0, default
+value is 1.0. A greater value will result in a more blurred image, and
+in slower processing.
+
+
+
‘luma_pre_filter_radius, lpfr’
+
Set luma pre-filter radius, must be a value in the 0.1-2.0 range, default
+value is 1.0.
+
+
+
‘luma_strength, ls’
+
Set luma maximum difference between pixels to still be considered, must
+be a value in the 0.1-100.0 range, default value is 1.0.
+
+
+
‘chroma_radius, cr’
+
Set chroma blur filter strength, must be a value in range 0.1-4.0. A
+greater value will result in a more blurred image, and in slower
+processing.
+
+
+
‘chroma_pre_filter_radius, cpfr’
+
Set chroma pre-filter radius, must be a value in the 0.1-2.0 range.
+
+
+
‘chroma_strength, cs’
+
Set chroma maximum difference between pixels to still be considered,
+must be a value in the 0.1-100.0 range.
+
+
+
+
Each chroma option value, if not explicitly specified, is set to the
+corresponding luma option value.
+
Scale (resize) the input video, using the libswscale library.
+
+
The scale filter forces the output display aspect ratio to be the same
+of the input, by changing the output sample aspect ratio.
+
+
If the input image format is different from the format requested by
+the next filter, the scale filter will convert the input to the
+requested format.
+
Set the output video dimension expression. Default value is the input
+dimension.
+
+
If the value is 0, the input width is used for the output.
+
+
If one of the values is -1, the scale filter will use a value that
+maintains the aspect ratio of the input image, calculated from the
+other specified dimension. If both of them are -1, the input size is
+used
+
+
See below for the list of accepted constants for use in the dimension
+expression.
+
+
+
‘interl’
+
Set the interlacing mode. It accepts the following values:
+
+
+
‘1’
+
Force interlaced aware scaling.
+
+
+
‘0’
+
Do not apply interlaced scaling.
+
+
+
‘-1’
+
Select interlaced aware scaling depending on whether the source frames
+are flagged as interlaced or not.
+
+
+
+
Default value is ‘0’.
+
+
+
‘flags’
+
Set libswscale scaling flags. See
+(ffmpeg-scaler)sws_flags for the
+complete list of values. If not explictly specified the filter applies
+the default flags.
+
+
+
‘size, s’
+
Set the video size. For the syntax of this option, check the "Video size"
+section in the ffmpeg-utils manual.
+
+
+
‘in_color_matrix’
+
‘out_color_matrix’
+
Set in/output YCbCr color space type.
+
+
This allows the autodetected value to be overridden as well as allows forcing
+a specific value used for the output and encoder.
+
+
If not specified, the color space type depends on the pixel format.
+
+
Possible values:
+
+
+
‘auto’
+
Choose automatically.
+
+
+
‘bt709’
+
Format conforming to International Telecommunication Union (ITU)
+Recommendation BT.709.
+
+
+
‘fcc’
+
Set color space conforming to the United States Federal Communications
+Commission (FCC) Code of Federal Regulations (CFR) Title 47 (2003) 73.682 (a).
+
+ITU-R Rec. BT.470-6 (1998) Systems B, B1, and G
+
+
+Society of Motion Picture and Television Engineers (SMPTE) ST 170:2004
+
+
+
+
+
‘smpte240m’
+
Set color space conforming to SMPTE ST 240:1999.
+
+
+
+
+
‘in_range’
+
‘out_range’
+
Set in/output YCbCr sample range.
+
+
This allows the autodetected value to be overridden as well as allows forcing
+a specific value used for the output and encoder. If not specified, the
+range depends on the pixel format. Possible values:
+
+
+
‘auto’
+
Choose automatically.
+
+
+
‘jpeg/full/pc’
+
Set full range (0-255 in case of 8-bit luma).
+
+
+
‘mpeg/tv’
+
Set "MPEG" range (16-235 in case of 8-bit luma).
+
+
+
+
+
‘force_original_aspect_ratio’
+
Enable decreasing or increasing output video width or height if necessary to
+keep the original aspect ratio. Possible values:
+
+
+
‘disable’
+
Scale the video as specified and disable this feature.
+
+
+
‘decrease’
+
The output video dimensions will automatically be decreased if needed.
+
+
+
‘increase’
+
The output video dimensions will automatically be increased if needed.
+
+
+
+
+
One useful instance of this option is that when you know a specific device’s
+maximum allowed resolution, you can use this to limit the output video to
+that, while retaining the aspect ratio. For example, device A allows
+1280x720 playback, and your video is 1920x800. Using this option (set it to
+decrease) and specifying 1280x720 to the command line makes the output
+1280x533.
+
+
Please note that this is a different thing than specifying -1 for ‘w’
+or ‘h’, you still need to specify the output resolution for this option
+to work.
+
+
+
+
+
The values of the ‘w’ and ‘h’ options are expressions
+containing the following constants:
+
The separatefields takes a frame-based video input and splits
+each frame into its components fields, producing a new half height clip
+with twice the frame rate and twice the frame count.
+
+
This filter use field-dominance information in frame to decide which
+of each pair of fields to place first in the output.
+If it gets it wrong use setfield filter before separatefields filter.
+
The setdar filter sets the Display Aspect Ratio for the filter
+output video.
+
+
This is done by changing the specified Sample (aka Pixel) Aspect
+Ratio, according to the following equation:
+
DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR
+
+
+
Keep in mind that the setdar filter does not modify the pixel
+dimensions of the video frame. Also the display aspect ratio set by
+this filter may be changed by later filters in the filterchain,
+e.g. in case of scaling or if another "setdar" or a "setsar" filter is
+applied.
+
+
The setsar filter sets the Sample (aka Pixel) Aspect Ratio for
+the filter output video.
+
+
Note that as a consequence of the application of this filter, the
+output display aspect ratio will change according to the equation
+above.
+
+
Keep in mind that the sample aspect ratio set by the setsar
+filter may be changed by later filters in the filterchain, e.g. if
+another "setsar" or a "setdar" filter is applied.
+
+
The filters accept the following options:
+
+
+
‘r, ratio, dar (setdar only), sar (setsar only)’
+
Set the aspect ratio used by the filter.
+
+
The parameter can be a floating point number string, an expression, or
+a string of the form num:den, where num and
+den are the numerator and denominator of the aspect ratio. If
+the parameter is not specified, it is assumed the value "0".
+In case the form "num:den" is used, the : character
+should be escaped.
+
+
+
‘max’
+
Set the maximum integer value to use for expressing numerator and
+denominator when reducing the expressed aspect ratio to a rational.
+Default value is 100.
+
The setfield filter marks the interlace type field for the
+output frames. It does not change the input frame, but only sets the
+corresponding property, which affects how the frame is treated by
+following filters (e.g. fieldorder or yadif).
+
Show a line containing various information for each input video frame.
+The input video is not modified.
+
+
The shown line contains a sequence of key/value pairs of the form
+key:value.
+
+
A description of each shown parameter follows:
+
+
+
‘n’
+
sequential number of the input frame, starting from 0
+
+
+
‘pts’
+
Presentation TimeStamp of the input frame, expressed as a number of
+time base units. The time base unit depends on the filter input pad.
+
+
+
‘pts_time’
+
Presentation TimeStamp of the input frame, expressed as a number of
+seconds
+
+
+
‘pos’
+
position of the frame in the input stream, -1 if this information in
+unavailable and/or meaningless (for example in case of synthetic video)
+
+
+
‘fmt’
+
pixel format name
+
+
+
‘sar’
+
sample aspect ratio of the input frame, expressed in the form
+num/den
+
+
+
‘s’
+
size of the input frame. For the syntax of this option, check the "Video size"
+section in the ffmpeg-utils manual.
+
+
+
‘i’
+
interlaced mode ("P" for "progressive", "T" for top field first, "B"
+for bottom field first)
+
+
+
‘iskey’
+
1 if the frame is a key frame, 0 otherwise
+
+
+
‘type’
+
picture type of the input frame ("I" for an I-frame, "P" for a
+P-frame, "B" for a B-frame, "?" for unknown type).
+Check also the documentation of the AVPictureType enum and of
+the av_get_picture_type_char function defined in
+‘libavutil/avutil.h’.
+
+
+
‘checksum’
+
Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame
+
+
+
‘plane_checksum’
+
Adler-32 checksum (printed in hexadecimal) of each plane of the input frame,
+expressed in the form "[c0c1c2c3]"
+
Blur the input video without impacting the outlines.
+
+
The filter accepts the following options:
+
+
+
‘luma_radius, lr’
+
Set the luma radius. The option value must be a float number in
+the range [0.1,5.0] that specifies the variance of the gaussian filter
+used to blur the image (slower if larger). Default value is 1.0.
+
+
+
‘luma_strength, ls’
+
Set the luma strength. The option value must be a float number
+in the range [-1.0,1.0] that configures the blurring. A value included
+in [0.0,1.0] will blur the image whereas a value included in
+[-1.0,0.0] will sharpen the image. Default value is 1.0.
+
+
+
‘luma_threshold, lt’
+
Set the luma threshold used as a coefficient to determine
+whether a pixel should be blurred or not. The option value must be an
+integer in the range [-30,30]. A value of 0 will filter all the image,
+a value included in [0,30] will filter flat areas and a value included
+in [-30,0] will filter edges. Default value is 0.
+
+
+
‘chroma_radius, cr’
+
Set the chroma radius. The option value must be a float number in
+the range [0.1,5.0] that specifies the variance of the gaussian filter
+used to blur the image (slower if larger). Default value is 1.0.
+
+
+
‘chroma_strength, cs’
+
Set the chroma strength. The option value must be a float number
+in the range [-1.0,1.0] that configures the blurring. A value included
+in [0.0,1.0] will blur the image whereas a value included in
+[-1.0,0.0] will sharpen the image. Default value is 1.0.
+
+
+
‘chroma_threshold, ct’
+
Set the chroma threshold used as a coefficient to determine
+whether a pixel should be blurred or not. The option value must be an
+integer in the range [-30,30]. A value of 0 will filter all the image,
+a value included in [0,30] will filter flat areas and a value included
+in [-30,0] will filter edges. Default value is 0.
+
+
+
+
If a chroma option is not explicitly set, the corresponding luma value
+is set.
+
Apply a simple postprocessing filter that compresses and decompresses the image
+at several (or - in the case of ‘quality’ level 6 - all) shifts
+and average the results.
+
+
The filter accepts the following options:
+
+
+
‘quality’
+
Set quality. This option defines the number of levels for averaging. It accepts
+an integer in the range 0-6. If set to 0, the filter will have no
+effect. A value of 6 means the higher quality. For each increment of
+that value the speed drops by a factor of approximately 2. Default value is
+3.
+
+
+
‘qp’
+
Force a constant quantization parameter. If not set, the filter will use the QP
+from the video stream (if available).
+
+
+
‘mode’
+
Set thresholding mode. Available modes are:
+
+
+
‘hard’
+
Set hard thresholding (default).
+
+
‘soft’
+
Set soft thresholding (better de-ringing effect, but likely blurrier).
+
+
+
+
+
‘use_bframe_qp’
+
Enable the use of the QP from the B-Frames if set to 1. Using this
+option may cause flicker since the B-Frames have often larger QP. Default is
+0 (not enabled).
+
Draw subtitles on top of input video using the libass library.
+
+
To enable compilation of this filter you need to configure FFmpeg with
+--enable-libass. This filter also requires a build with libavcodec and
+libavformat to convert the passed subtitles file to ASS (Advanced Substation
+Alpha) subtitles format.
+
+
The filter accepts the following options:
+
+
+
‘filename, f’
+
Set the filename of the subtitle file to read. It must be specified.
+
+
+
‘original_size’
+
Specify the size of the original video, the video for which the ASS file
+was composed. For the syntax of this option, check the "Video size" section in
+the ffmpeg-utils manual. Due to a misdesign in ASS aspect ratio arithmetic,
+this is necessary to correctly scale the fonts if the aspect ratio has been
+changed.
+
+
+
‘charenc’
+
Set subtitles input character encoding. subtitles filter only. Only
+useful if not UTF-8.
+
+
+
+
If the first key is not specified, it is assumed that the first value
+specifies the ‘filename’.
+
+
For example, to render the file ‘sub.srt’ on top of the input
+video, use the command:
+
Select the most representative frame in a given sequence of consecutive frames.
+
+
The filter accepts the following options:
+
+
+
‘n’
+
Set the frames batch size to analyze; in a set of n frames, the filter
+will pick one of them, and then handle the next batch of n frames until
+the end. Default is 100.
+
+
+
+
Since the filter keeps track of the whole frames sequence, a bigger n
+value will result in a higher memory usage, so a high value is not recommended.
+
Set the grid size (i.e. the number of lines and columns). For the syntax of
+this option, check the "Video size" section in the ffmpeg-utils manual.
+
+
+
‘nb_frames’
+
Set the maximum number of frames to render in the given area. It must be less
+than or equal to wxh. The default value is 0, meaning all
+the area will be used.
+
+
+
‘margin’
+
Set the outer border margin in pixels.
+
+
+
‘padding’
+
Set the inner border thickness (i.e. the number of pixels between frames). For
+more advanced padding options (such as having different values for the edges),
+refer to the pad video filter.
+
+
+
‘color’
+
Specify the color of the unused areaFor the syntax of this option, check the
+"Color" section in the ffmpeg-utils manual. The default value of color
+is "black".
+
Perform various types of temporal field interlacing.
+
+
Frames are counted starting from 1, so the first input frame is
+considered odd.
+
+
The filter accepts the following options:
+
+
+
‘mode’
+
Specify the mode of the interlacing. This option can also be specified
+as a value alone. See below for a list of values for this option.
+
+
Available values are:
+
+
+
‘merge, 0’
+
Move odd frames into the upper field, even into the lower field,
+generating a double height frame at half frame rate.
+
+
+
‘drop_odd, 1’
+
Only output even frames, odd frames are dropped, generating a frame with
+unchanged height at half frame rate.
+
+
+
‘drop_even, 2’
+
Only output odd frames, even frames are dropped, generating a frame with
+unchanged height at half frame rate.
+
+
+
‘pad, 3’
+
Expand each frame to full height, but pad alternate lines with black,
+generating a frame with double height at the same input frame rate.
+
+
+
‘interleave_top, 4’
+
Interleave the upper field from odd frames with the lower field from
+even frames, generating a frame with unchanged height at half frame rate.
+
+
+
‘interleave_bottom, 5’
+
Interleave the lower field from odd frames with the upper field from
+even frames, generating a frame with unchanged height at half frame rate.
+
+
+
‘interlacex2, 6’
+
Double frame rate with unchanged height. Frames are inserted each
+containing the second temporal field from the previous input frame and
+the first temporal field from the next input frame. This mode relies on
+the top_field_first flag. Useful for interlaced video displays with no
+field synchronisation.
+
+
+
+
Numeric values are deprecated but are accepted for backward
+compatibility reasons.
+
+
Default mode is merge.
+
+
+
‘flags’
+
Specify flags influencing the filter process.
+
+
Available value for flags is:
+
+
+
‘low_pass_filter, vlfp’
+
Enable vertical low-pass filtering in the filter.
+Vertical low-pass filtering is required when creating an interlaced
+destination from a progressive source which contains high-frequency
+vertical detail. Filtering will reduce interlace ’twitter’ and Moire
+patterning.
+
+
Vertical low-pass filtering can only be enabled for ‘mode’
+interleave_top and interleave_bottom.
+
Transpose rows with columns in the input video and optionally flip it.
+
+
This filter accepts the following options:
+
+
+
‘dir’
+
Specify the transposition direction.
+
+
Can assume the following values:
+
+
‘0, 4, cclock_flip’
+
Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
+
L.R L.l
+. . -> . .
+l.r R.r
+
+
+
+
‘1, 5, clock’
+
Rotate by 90 degrees clockwise, that is:
+
L.R l.L
+. . -> . .
+l.r r.R
+
+
+
+
‘2, 6, cclock’
+
Rotate by 90 degrees counterclockwise, that is:
+
L.R R.r
+. . -> . .
+l.r L.l
+
+
+
+
‘3, 7, clock_flip’
+
Rotate by 90 degrees clockwise and vertically flip, that is:
+
L.R r.R
+. . -> . .
+l.r l.L
+
+
+
+
+
For values between 4-7, the transposition is only done if the input
+video geometry is portrait and not landscape. These values are
+deprecated, the passthrough option should be used instead.
+
+
Numerical values are deprecated, and should be dropped in favor of
+symbolic constants.
+
+
+
‘passthrough’
+
Do not apply the transposition if the input geometry matches the one
+specified by the specified value. It accepts the following values:
+
Trim the input so that the output contains one continuous subpart of the input.
+
+
This filter accepts the following options:
+
+
‘start’
+
Specify time of the start of the kept section, i.e. the frame with the
+timestamp start will be the first frame in the output.
+
+
+
‘end’
+
Specify time of the first frame that will be dropped, i.e. the frame
+immediately preceding the one with the timestamp end will be the last
+frame in the output.
+
+
+
‘start_pts’
+
Same as start, except this option sets the start timestamp in timebase
+units instead of seconds.
+
+
+
‘end_pts’
+
Same as end, except this option sets the end timestamp in timebase units
+instead of seconds.
+
+
+
‘duration’
+
Specify maximum duration of the output.
+
+
+
‘start_frame’
+
Number of the first frame that should be passed to output.
+
+
+
‘end_frame’
+
Number of the first frame that should be dropped.
+
+
+
+
‘start’, ‘end’, ‘duration’ are expressed as time
+duration specifications, check the "Time duration" section in the
+ffmpeg-utils manual.
+
+
Note that the first two sets of the start/end options and the ‘duration’
+option look at the frame timestamp, while the _frame variants simply count the
+frames that pass through the filter. Also note that this filter does not modify
+the timestamps. If you wish that the output timestamps start at zero, insert a
+setpts filter after the trim filter.
+
+
If multiple start or end options are set, this filter tries to be greedy and
+keep all the frames that match at least one of the specified constraints. To keep
+only the part that matches all the constraints at once, chain multiple trim
+filters.
+
+
The defaults are such that all the input is kept. So it is possible to set e.g.
+just the end values to keep everything before the specified time.
+
+
Examples:
+
+
+drop everything except the second minute of input
+
Analyze video stabilization/deshaking. Perform pass 1 of 2, see
+vidstabtransform for pass 2.
+
+
This filter generates a file with relative translation and rotation
+transform information about subsequent frames, which is then used by
+the vidstabtransform filter.
+
+
To enable compilation of this filter you need to configure FFmpeg with
+--enable-libvidstab.
+
+
This filter accepts the following options:
+
+
+
‘result’
+
Set the path to the file used to write the transforms information.
+Default value is ‘transforms.trf’.
+
+
+
‘shakiness’
+
Set how shaky the video is and how quick the camera is. It accepts an
+integer in the range 1-10, a value of 1 means little shakiness, a
+value of 10 means strong shakiness. Default value is 5.
+
+
+
‘accuracy’
+
Set the accuracy of the detection process. It must be a value in the
+range 1-15. A value of 1 means low accuracy, a value of 15 means high
+accuracy. Default value is 9.
+
+
+
‘stepsize’
+
Set stepsize of the search process. The region around minimum is
+scanned with 1 pixel resolution. Default value is 6.
+
+
+
‘mincontrast’
+
Set minimum contrast. Below this value a local measurement field is
+discarded. Must be a floating point value in the range 0-1. Default
+value is 0.3.
+
+
+
‘tripod’
+
Set reference frame number for tripod mode.
+
+
If enabled, the motion of the frames is compared to a reference frame
+in the filtered stream, identified by the specified number. The idea
+is to compensate all movements in a more-or-less static scene and keep
+the camera view absolutely still.
+
+
If set to 0, it is disabled. The frames are counted starting from 1.
+
+
+
‘show’
+
Show fields and transforms in the resulting frames. It accepts an
+integer in the range 0-2. Default value is 0, which disables any
+visualization.
+
Video stabilization/deshaking: pass 2 of 2,
+see vidstabdetect for pass 1.
+
+
Read a file with transform information for each frame and
+apply/compensate them. Together with the vidstabdetect
+filter this can be used to deshake videos. See also
+http://public.hronopik.de/vid.stab. It is important to also use
+the unsharp filter, see below.
+
+
To enable compilation of this filter you need to configure FFmpeg with
+--enable-libvidstab.
+
+
This filter accepts the following options:
+
+
+
‘input’
+
path to the file used to read the transforms (default: ‘transforms.trf’)
+
+
+
‘smoothing’
+
number of frames (value*2 + 1) used for lowpass filtering the camera movements
+(default: 10). For example a number of 10 means that 21 frames are used
+(10 in the past and 10 in the future) to smoothen the motion in the
+video. A larger values leads to a smoother video, but limits the
+acceleration of the camera (pan/tilt movements).
+
+
+
‘maxshift’
+
maximal number of pixels to translate frames (default: -1 no limit)
+
+
+
‘maxangle’
+
maximal angle in radians (degree*PI/180) to rotate frames (default: -1
+no limit)
+
+
+
‘crop’
+
How to deal with borders that may be visible due to movement
+compensation. Available values are:
+
+
+
‘keep’
+
keep image information from previous frame (default)
+
+
‘black’
+
fill the border black
+
+
+
+
+
‘invert’
+
+
‘0’
+
keep transforms normal (default)
+
+
‘1’
+
invert transforms
+
+
+
+
+
‘relative’
+
consider transforms as
+
+
‘0’
+
absolute
+
+
‘1’
+
relative to previous frame (default)
+
+
+
+
+
‘zoom’
+
percentage to zoom (default: 0)
+
+
‘>0’
+
zoom in
+
+
‘<0’
+
zoom out
+
+
+
+
+
‘optzoom’
+
set optimal zooming to avoid borders
+
+
‘0’
+
disabled
+
+
‘1’
+
optimal static zoom value is determined (only very strong movements will lead to visible borders) (default)
+
+
‘2’
+
optimal adaptive zoom value is determined (no borders will be visible)
+
+
+
Note that the value given at zoom is added to the one calculated
+here.
+
+
+
‘interpol’
+
type of interpolation
+
+
Available values are:
+
+
‘no’
+
no interpolation
+
+
‘linear’
+
linear only horizontal
+
+
‘bilinear’
+
linear in both directions (default)
+
+
‘bicubic’
+
cubic in both directions (slow)
+
+
+
+
+
‘tripod’
+
virtual tripod mode means that the video is stabilized such that the
+camera stays stationary. Use also tripod option of
+vidstabdetect.
+
+
‘0’
+
off (default)
+
+
‘1’
+
virtual tripod mode: equivalent to relative=0:smoothing=0
+
Set lens angle expression as a number of radians.
+
+
The value is clipped in the [0,PI/2] range.
+
+
Default value: "PI/5"
+
+
+
‘x0’
+
‘y0’
+
Set center coordinates expressions. Respectively "w/2" and "h/2"
+by default.
+
+
+
‘mode’
+
Set forward/backward mode.
+
+
Available modes are:
+
+
‘forward’
+
The larger the distance from the central point, the darker the image becomes.
+
+
+
‘backward’
+
The larger the distance from the central point, the brighter the image becomes.
+This can be used to reverse a vignette effect, though there is no automatic
+detection to extract the lens ‘angle’ and other settings (yet). It can
+also be used to create a burning effect.
+
+
+
+
Default value is ‘forward’.
+
+
+
‘eval’
+
Set evaluation mode for the expressions (‘angle’, ‘x0’, ‘y0’).
+
+
It accepts the following values:
+
+
‘init’
+
Evaluate expressions only once during the filter initialization.
+
+
+
‘frame’
+
Evaluate expressions for each incoming frame. This is way slower than the
+‘init’ mode since it requires all the scalers to be re-computed, but it
+allows advanced dynamic expressions.
+
+
+
+
Default value is ‘init’.
+
+
+
‘dither’
+
Set dithering to reduce the circular banding effects. Default is 1
+(enabled).
+
+
+
‘aspect’
+
Set vignette aspect. This setting allows to adjust the shape of the vignette.
+Setting this value to the SAR of the input will make a rectangular vignetting
+following the dimensions of the video.
+
Deinterlace the input video ("w3fdif" stands for "Weston 3 Field
+Deinterlacing Filter").
+
+
Based on the process described by Martin Weston for BBC R&D, and
+implemented based on the de-interlace algorithm written by Jim
+Easterbrook for BBC R&D, the Weston 3 field deinterlacing filter
+uses filter coefficients calculated by BBC R&D.
+
+
There are two sets of filter coefficients, so called "simple":
+and "complex". Which set of filter coefficients is used can
+be set by passing an optional parameter:
+
+
+
‘filter’
+
Set the interlacing filter coefficients. Accepts one of the following values:
+
+
+
‘simple’
+
Simple filter coefficient set.
+
+
‘complex’
+
More-complex filter coefficient set.
+
+
+
Default value is ‘complex’.
+
+
+
‘deint’
+
Specify which frames to deinterlace. Accept one of the following values:
+
Buffer video frames, and make them available to the filter chain.
+
+
This source is mainly intended for a programmatic use, in particular
+through the interface defined in ‘libavfilter/vsrc_buffer.h’.
+
+
This source accepts the following options:
+
+
+
‘video_size’
+
Specify the size (width and height) of the buffered video frames. For the
+syntax of this option, check the "Video size" section in the ffmpeg-utils
+manual.
+
+
+
‘width’
+
Input video width.
+
+
+
‘height’
+
Input video height.
+
+
+
‘pix_fmt’
+
A string representing the pixel format of the buffered video frames.
+It may be a number corresponding to a pixel format, or a pixel format
+name.
+
+
+
‘time_base’
+
Specify the timebase assumed by the timestamps of the buffered frames.
+
+
+
‘frame_rate’
+
Specify the frame rate expected for the video stream.
+
+
+
‘pixel_aspect, sar’
+
Specify the sample aspect ratio assumed by the video frames.
+
+
+
‘sws_param’
+
Specify the optional parameters to be used for the scale filter which
+is automatically inserted when an input change is detected in the
+input size or format.
+
will instruct the source to accept video frames with size 320x240 and
+with format "yuv410p", assuming 1/24 as the timestamps timebase and
+square pixels (1:1 sample aspect ratio).
+Since the pixel format with name "yuv410p" corresponds to the number 6
+(check the enum AVPixelFormat definition in ‘libavutil/pixfmt.h’),
+this example corresponds to:
+
Create a pattern generated by an elementary cellular automaton.
+
+
The initial state of the cellular automaton can be defined through the
+‘filename’, and ‘pattern’ options. If such options are
+not specified an initial state is created randomly.
+
+
At each new frame a new row in the video is filled with the result of
+the cellular automaton next generation. The behavior when the whole
+frame is filled is defined by the ‘scroll’ option.
+
+
This source accepts the following options:
+
+
+
‘filename, f’
+
Read the initial cellular automaton state, i.e. the starting row, from
+the specified file.
+In the file, each non-whitespace character is considered an alive
+cell, a newline will terminate the row, and further characters in the
+file will be ignored.
+
+
+
‘pattern, p’
+
Read the initial cellular automaton state, i.e. the starting row, from
+the specified string.
+
+
Each non-whitespace character in the string is considered an alive
+cell, a newline will terminate the row, and further characters in the
+string will be ignored.
+
+
+
‘rate, r’
+
Set the video rate, that is the number of frames generated per second.
+Default is 25.
+
+
+
‘random_fill_ratio, ratio’
+
Set the random fill ratio for the initial cellular automaton row. It
+is a floating point number value ranging from 0 to 1, defaults to
+1/PHI.
+
+
This option is ignored when a file or a pattern is specified.
+
+
+
‘random_seed, seed’
+
Set the seed for filling randomly the initial row, must be an integer
+included between 0 and UINT32_MAX. If not specified, or if explicitly
+set to -1, the filter will try to use a good random seed on a best
+effort basis.
+
+
+
‘rule’
+
Set the cellular automaton rule, it is a number ranging from 0 to 255.
+Default value is 110.
+
+
+
‘size, s’
+
Set the size of the output video. For the syntax of this option, check
+the "Video size" section in the ffmpeg-utils manual.
+
+
If ‘filename’ or ‘pattern’ is specified, the size is set
+by default to the width of the specified initial state row, and the
+height is set to width * PHI.
+
+
If ‘size’ is set, it must contain the width of the specified
+pattern string, and the specified pattern will be centered in the
+larger row.
+
+
If a filename or a pattern string is not specified, the size value
+defaults to "320x518" (used for a randomly generated initial state).
+
+
+
‘scroll’
+
If set to 1, scroll the output upward when all the rows in the output
+have been already filled. If set to 0, the new generated row will be
+written over the top row just after the bottom row is filled.
+Defaults to 1.
+
+
+
‘start_full, full’
+
If set to 1, completely fill the output with generated rows before
+outputting the first frame.
+This is the default behavior, for disabling set the value to 0.
+
+
+
‘stitch’
+
If set to 1, stitch the left and right row edges together.
+This is the default behavior, for disabling set the value to 0.
+
Generate various test patterns, as generated by the MPlayer test filter.
+
+
The size of the generated video is fixed, and is 256x256.
+This source is useful in particular for testing encoding features.
+
+
This source accepts the following options:
+
+
+
‘rate, r’
+
Specify the frame rate of the sourced video, as the number of frames
+generated per second. It has to be a string in the format
+frame_rate_num/frame_rate_den, an integer number, a float
+number or a valid video frame rate abbreviation. The default value is
+"25".
+
+
+
‘duration, d’
+
Set the video duration of the sourced video. The accepted syntax is:
+
[-]HH:MM:SS[.m...]
+[-]S+[.m...]
+
+
See also the function av_parse_time().
+
+
If not specified, or the expressed duration is negative, the video is
+supposed to be generated forever.
+
+
+
‘test, t’
+
+
Set the number or the name of the test to perform. Supported tests are:
+
+
‘dc_luma’
+
‘dc_chroma’
+
‘freq_luma’
+
‘freq_chroma’
+
‘amp_luma’
+
‘amp_chroma’
+
‘cbp’
+
‘mv’
+
‘ring1’
+
‘ring2’
+
‘all’
+
+
+
Default value is "all", which will cycle through the list of all tests.
+
To enable compilation of this filter you need to install the frei0r
+header and configure FFmpeg with --enable-frei0r.
+
+
This source accepts the following options:
+
+
+
‘size’
+
The size of the video to generate. For the syntax of this option, check the
+"Video size" section in the ffmpeg-utils manual.
+
+
+
‘framerate’
+
Framerate of the generated video, may be a string of the form
+num/den or a frame rate abbreviation.
+
+
+
‘filter_name’
+
The name to the frei0r source to load. For more information regarding frei0r and
+how to set the parameters read the section frei0r in the description of
+the video filters.
+
+
+
‘filter_params’
+
A ’|’-separated list of parameters to pass to the frei0r source.
+
+
+
+
+
For example, to generate a frei0r partik0l source with size 200x200
+and frame rate 10 which is overlayed on the overlay filter main input:
+
This source is based on a generalization of John Conway’s life game.
+
+
The sourced input represents a life grid, each pixel represents a cell
+which can be in one of two possible states, alive or dead. Every cell
+interacts with its eight neighbours, which are the cells that are
+horizontally, vertically, or diagonally adjacent.
+
+
At each interaction the grid evolves according to the adopted rule,
+which specifies the number of neighbor alive cells which will make a
+cell stay alive or born. The ‘rule’ option allows to specify
+the rule to adopt.
+
+
This source accepts the following options:
+
+
+
‘filename, f’
+
Set the file from which to read the initial grid state. In the file,
+each non-whitespace character is considered an alive cell, and newline
+is used to delimit the end of each row.
+
+
If this option is not specified, the initial grid is generated
+randomly.
+
+
+
‘rate, r’
+
Set the video rate, that is the number of frames generated per second.
+Default is 25.
+
+
+
‘random_fill_ratio, ratio’
+
Set the random fill ratio for the initial random grid. It is a
+floating point number value ranging from 0 to 1, defaults to 1/PHI.
+It is ignored when a file is specified.
+
+
+
‘random_seed, seed’
+
Set the seed for filling the initial random grid, must be an integer
+included between 0 and UINT32_MAX. If not specified, or if explicitly
+set to -1, the filter will try to use a good random seed on a best
+effort basis.
+
+
+
‘rule’
+
Set the life rule.
+
+
A rule can be specified with a code of the kind "SNS/BNB",
+where NS and NB are sequences of numbers in the range 0-8,
+NS specifies the number of alive neighbor cells which make a
+live cell stay alive, and NB the number of alive neighbor cells
+which make a dead cell to become alive (i.e. to "born").
+"s" and "b" can be used in place of "S" and "B", respectively.
+
+
Alternatively a rule can be specified by an 18-bits integer. The 9
+high order bits are used to encode the next cell state if it is alive
+for each number of neighbor alive cells, the low order bits specify
+the rule for "borning" new cells. Higher order bits encode for an
+higher number of neighbor cells.
+For example the number 6153 = (12<<9)+9 specifies a stay alive
+rule of 12 and a born rule of 9, which corresponds to "S23/B03".
+
+
Default value is "S23/B3", which is the original Conway’s game of life
+rule, and will keep a cell alive if it has 2 or 3 neighbor alive
+cells, and will born a new cell if there are three alive cells around
+a dead cell.
+
+
+
‘size, s’
+
Set the size of the output video. For the syntax of this option, check the
+"Video size" section in the ffmpeg-utils manual.
+
+
If ‘filename’ is specified, the size is set by default to the
+same size of the input file. If ‘size’ is set, it must contain
+the size specified in the input file, and the initial grid defined in
+that file is centered in the larger resulting area.
+
+
If a filename is not specified, the size value defaults to "320x240"
+(used for a randomly generated initial grid).
+
+
+
‘stitch’
+
If set to 1, stitch the left and right grid edges together, and the
+top and bottom edges also. Defaults to 1.
+
+
+
‘mold’
+
Set cell mold speed. If set, a dead cell will go from ‘death_color’ to
+‘mold_color’ with a step of ‘mold’. ‘mold’ can have a
+value from 0 to 255.
+
+
+
‘life_color’
+
Set the color of living (or new born) cells.
+
+
+
‘death_color’
+
Set the color of dead cells. If ‘mold’ is set, this is the first color
+used to represent a dead cell.
+
+
+
‘mold_color’
+
Set mold color, for definitely dead and moldy cells.
+
+
For the syntax of these 3 color options, check the "Color" section in the
+ffmpeg-utils manual.
+
The color source provides an uniformly colored input.
+
+
The haldclutsrc source provides an identity Hald CLUT. See also
+haldclut filter.
+
+
The nullsrc source returns unprocessed video frames. It is
+mainly useful to be employed in analysis / debugging tools, or as the
+source for filters which ignore the input data.
+
+
The rgbtestsrc source generates an RGB test pattern useful for
+detecting RGB vs BGR issues. You should see a red, green and blue
+stripe from top to bottom.
+
+
The smptebars source generates a color bars pattern, based on
+the SMPTE Engineering Guideline EG 1-1990.
+
+
The smptehdbars source generates a color bars pattern, based on
+the SMPTE RP 219-2002.
+
+
The testsrc source generates a test video pattern, showing a
+color pattern, a scrolling gradient and a timestamp. This is mainly
+intended for testing purposes.
+
+
The sources accept the following options:
+
+
+
‘color, c’
+
Specify the color of the source, only available in the color
+source. For the syntax of this option, check the "Color" section in the
+ffmpeg-utils manual.
+
+
+
‘level’
+
Specify the level of the Hald CLUT, only available in the haldclutsrc
+source. A level of N generates a picture of N*N*N by N*N*N
+pixels to be used as identity matrix for 3D lookup tables. Each component is
+coded on a 1/(N*N) scale.
+
+
+
‘size, s’
+
Specify the size of the sourced video. For the syntax of this option, check the
+"Video size" section in the ffmpeg-utils manual. The default value is
+"320x240".
+
+
This option is not available with the haldclutsrc filter.
+
+
+
‘rate, r’
+
Specify the frame rate of the sourced video, as the number of frames
+generated per second. It has to be a string in the format
+frame_rate_num/frame_rate_den, an integer number, a float
+number or a valid video frame rate abbreviation. The default value is
+"25".
+
+
+
‘sar’
+
Set the sample aspect ratio of the sourced video.
+
+
+
‘duration, d’
+
Set the video duration of the sourced video. The accepted syntax is:
+
[-]HH[:MM[:SS[.m...]]]
+[-]S+[.m...]
+
+
See also the function av_parse_time().
+
+
If not specified, or the expressed duration is negative, the video is
+supposed to be generated forever.
+
+
+
‘decimals, n’
+
Set the number of decimals to show in the timestamp, only available in the
+testsrc source.
+
+
The displayed timestamp value will correspond to the original
+timestamp value multiplied by the power of 10 of the specified
+value. Default value is 0.
+
+
+
+
For example the following:
+
testsrc=duration=5.3:size=qcif:rate=10
+
+
+
will generate a video with a duration of 5.3 seconds, with size
+176x144 and a frame rate of 10 frames per second.
+
+
The following graph description will generate a red source
+with an opacity of 0.2, with size "qcif" and a frame rate of 10
+frames per second.
+
color=c=red@0.2:s=qcif:r=10
+
+
+
If the input content is to be ignored, nullsrc can be used. The
+following command generates noise in the luminance plane by employing
+the geq filter:
+
Buffer video frames, and make them available to the end of the filter
+graph.
+
+
This sink is mainly intended for a programmatic use, in particular
+through the interface defined in ‘libavfilter/buffersink.h’
+or the options system.
+
+
It accepts a pointer to an AVBufferSinkContext structure, which
+defines the incoming buffers’ formats, to be passed as the opaque
+parameter to avfilter_init_filter for initialization.
+
Convert input audio to a video output, representing the audio vector
+scope.
+
+
The filter is used to measure the difference between channels of stereo
+audio stream. A monoaural signal, consisting of identical left and right
+signal, results in straight vertical line. Any stereo separation is visible
+as a deviation from this line, creating a Lissajous figure.
+If the straight (or deviation from it) but horizontal line appears this
+indicates that the left and right channels are out of phase.
+
+
The filter accepts the following options:
+
+
+
‘mode, m’
+
Set the vectorscope mode.
+
+
Available values are:
+
+
‘lissajous’
+
Lissajous rotated by 45 degrees.
+
+
+
‘lissajous_xy’
+
Same as above but not rotated.
+
+
+
+
Default value is ‘lissajous’.
+
+
+
‘size, s’
+
Set the video size for the output. For the syntax of this option, check the "Video size"
+section in the ffmpeg-utils manual. Default value is 400x400.
+
+
+
‘rate, r’
+
Set the output frame rate. Default value is 25.
+
+
+
‘rc’
+
‘gc’
+
‘bc’
+
Specify the red, green and blue contrast. Default values are 40, 160 and 80.
+Allowed range is [0, 255].
+
+
+
‘rf’
+
‘gf’
+
‘bf’
+
Specify the red, green and blue fade. Default values are 15, 10 and 5.
+Allowed range is [0, 255].
+
+
+
‘zoom’
+
Set the zoom factor. Default value is 1. Allowed range is [1, 10].
+
Concatenate audio and video streams, joining them together one after the
+other.
+
+
The filter works on segments of synchronized video and audio streams. All
+segments must have the same number of streams of each type, and that will
+also be the number of streams at output.
+
+
The filter accepts the following options:
+
+
+
‘n’
+
Set the number of segments. Default is 2.
+
+
+
‘v’
+
Set the number of output video streams, that is also the number of video
+streams in each segment. Default is 1.
+
+
+
‘a’
+
Set the number of output audio streams, that is also the number of video
+streams in each segment. Default is 0.
+
+
+
‘unsafe’
+
Activate unsafe mode: do not fail if segments have a different format.
+
+
+
+
+
The filter has v+a outputs: first v video outputs, then
+a audio outputs.
+
+
There are nx(v+a) inputs: first the inputs for the first
+segment, in the same order as the outputs, then the inputs for the second
+segment, etc.
+
+
Related streams do not always have exactly the same duration, for various
+reasons including codec frame size or sloppy authoring. For that reason,
+related synchronized streams (e.g. a video and its audio track) should be
+concatenated at once. The concat filter will use the duration of the longest
+stream in each segment (except the last one), and if necessary pad shorter
+audio streams with silence.
+
+
For this filter to work correctly, all segments must start at timestamp 0.
+
+
All corresponding streams must have the same parameters in all segments; the
+filtering system will automatically select a common pixel format for video
+streams, and a common sample format, sample rate and channel layout for
+audio streams, but other settings, such as resolution, must be converted
+explicitly by the user.
+
+
Different frame rates are acceptable but will result in variable frame rate
+at output; be sure to configure the output file to handle it.
+
EBU R128 scanner filter. This filter takes an audio stream as input and outputs
+it unchanged. By default, it logs a message at a frequency of 10Hz with the
+Momentary loudness (identified by M), Short-term loudness (S),
+Integrated loudness (I) and Loudness Range (LRA).
+
+
The filter also has a video output (see the video option) with a real
+time graph to observe the loudness evolution. The graphic contains the logged
+message mentioned above, so it is not printed anymore when this option is set,
+unless the verbose logging is set. The main graphing area contains the
+short-term loudness (3 seconds of analysis), and the gauge on the right is for
+the momentary loudness (400 milliseconds).
+
Activate the video output. The audio stream is passed unchanged whether this
+option is set or no. The video stream will be the first output stream if
+activated. Default is 0.
+
+
+
‘size’
+
Set the video size. This option is for video only. For the syntax of this
+option, check the "Video size" section in the ffmpeg-utils manual. Default
+and minimum resolution is 640x480.
+
+
+
‘meter’
+
Set the EBU scale meter. Default is 9. Common values are 9 and
+18, respectively for EBU scale meter +9 and EBU scale meter +18. Any
+other integer value between this range is allowed.
+
+
+
‘metadata’
+
Set metadata injection. If set to 1, the audio input will be segmented
+into 100ms output frames, each of them containing various loudness information
+in metadata. All the metadata keys are prefixed with lavfi.r128..
+
+
Default is 0.
+
+
+
‘framelog’
+
Force the frame logging level.
+
+
Available values are:
+
+
‘info’
+
information logging level
+
+
‘verbose’
+
verbose logging level
+
+
+
+
By default, the logging level is set to info. If the ‘video’ or
+the ‘metadata’ options are set, it switches to verbose.
+
Temporally interleave frames from several inputs.
+
+
interleave works with video inputs, ainterleave with audio.
+
+
These filters read frames from several inputs and send the oldest
+queued frame to the output.
+
+
Input streams must have a well defined, monotonically increasing frame
+timestamp values.
+
+
In order to submit one frame to output, these filters need to enqueue
+at least one frame for each input, so they cannot work in case one
+input is not yet terminated and will not receive incoming frames.
+
+
For example consider the case when one input is a select filter
+which always drop input frames. The interleave filter will keep
+reading from that input, but it will never be able to send new frames
+to output until the input will send an end-of-stream signal.
+
+
Also, depending on inputs synchronization, the filters will drop
+frames in case one input receives more frames than the other ones, and
+the queue is already filled.
+
+
These filters accept the following options:
+
+
+
‘nb_inputs, n’
+
Set the number of different inputs, it is 2 by default.
+
Set read/write permissions for the output frames.
+
+
These filters are mainly aimed at developers to test direct path in the
+following filter in the filtergraph.
+
+
The filters accept the following options:
+
+
+
‘mode’
+
Select the permissions mode.
+
+
It accepts the following values:
+
+
‘none’
+
Do nothing. This is the default.
+
+
‘ro’
+
Set all the output frames read-only.
+
+
‘rw’
+
Set all the output frames directly writable.
+
+
‘toggle’
+
Make the frame read-only if writable, and writable if read-only.
+
+
‘random’
+
Set each output frame read-only or writable randomly.
+
+
+
+
+
‘seed’
+
Set the seed for the random mode, must be an integer included between
+0 and UINT32_MAX. If not specified, or if explicitly set to
+-1, the filter will try to use a good random seed on a best effort
+basis.
+
+
+
+
Note: in case of auto-inserted filter between the permission filter and the
+following one, the permission might not be received as expected in that
+following filter. Inserting a format or aformat filter before the
+perms/aperms filter can avoid this problem.
+
Set expression, which is evaluated for each input frame.
+
+
If the expression is evaluated to zero, the frame is discarded.
+
+
If the evaluation result is negative or NaN, the frame is sent to the
+first output; otherwise it is sent to the output with index
+ceil(val)-1, assuming that the input index starts from 0.
+
+
For example a value of 1.2 corresponds to the output with index
+ceil(1.2)-1 = 2-1 = 1, that is the second output.
+
+
+
‘outputs, n’
+
Set the number of outputs. The output to which to send the selected
+frame is based on the result of the evaluation. Default value is 1.
+
+
+
+
The expression can contain the following constants:
+
+
+
‘n’
+
the sequential number of the filtered frame, starting from 0
+
+
+
‘selected_n’
+
the sequential number of the selected frame, starting from 0
+
+
+
‘prev_selected_n’
+
the sequential number of the last selected frame, NAN if undefined
+
+
+
‘TB’
+
timebase of the input timestamps
+
+
+
‘pts’
+
the PTS (Presentation TimeStamp) of the filtered video frame,
+expressed in TB units, NAN if undefined
+
+
+
‘t’
+
the PTS (Presentation TimeStamp) of the filtered video frame,
+expressed in seconds, NAN if undefined
+
+
+
‘prev_pts’
+
the PTS of the previously filtered video frame, NAN if undefined
+
+
+
‘prev_selected_pts’
+
the PTS of the last previously filtered video frame, NAN if undefined
+
+
+
‘prev_selected_t’
+
the PTS of the last previously selected video frame, NAN if undefined
+
+
+
‘start_pts’
+
the PTS of the first video frame in the video, NAN if undefined
+
+
+
‘start_t’
+
the time of the first video frame in the video, NAN if undefined
+
+
+
‘pict_type (video only)’
+
the type of the filtered frame, can assume one of the following
+values:
+
+
‘I’
+
‘P’
+
‘B’
+
‘S’
+
‘SI’
+
‘SP’
+
‘BI’
+
+
+
+
‘interlace_type (video only)’
+
the frame interlace type, can assume one of the following values:
+
+
‘PROGRESSIVE’
+
the frame is progressive (not interlaced)
+
+
‘TOPFIRST’
+
the frame is top-field-first
+
+
‘BOTTOMFIRST’
+
the frame is bottom-field-first
+
+
+
+
+
‘consumed_sample_n (audio only)’
+
the number of selected samples before the current frame
+
+
+
‘samples_n (audio only)’
+
the number of samples in the current frame
+
+
+
‘sample_rate (audio only)’
+
the input sample rate
+
+
+
‘key’
+
1 if the filtered frame is a key-frame, 0 otherwise
+
+
+
‘pos’
+
the position in the file of the filtered frame, -1 if the information
+is not available (e.g. for synthetic video)
+
+
+
‘scene (video only)’
+
value between 0 and 1 to indicate a new scene; a low value reflects a low
+probability for the current frame to introduce a new scene, while a higher
+value means the current frame is more likely to be one (see the example below)
+
+
+
+
+
The default value of the select expression is "1".
+
These filters read commands to be sent to other filters in the
+filtergraph.
+
+
sendcmd must be inserted between two video filters,
+asendcmd must be inserted between two audio filters, but apart
+from that they act the same way.
+
+
The specification of commands can be provided in the filter arguments
+with the commands option, or in a file specified by the
+filename option.
+
+
These filters accept the following options:
+
+
‘commands, c’
+
Set the commands to be read and sent to the other filters.
+
+
‘filename, f’
+
Set the filename of the commands to be read and sent to the other
+filters.
+
A commands description consists of a sequence of interval
+specifications, comprising a list of commands to be executed when a
+particular event related to that interval occurs. The occurring event
+is typically the current frame time entering or leaving a given time
+interval.
+
+
An interval is specified by the following syntax:
+
START[-END] COMMANDS;
+
+
+
The time interval is specified by the START and END times.
+END is optional and defaults to the maximum time.
+
+
The current frame time is considered within the specified interval if
+it is included in the interval [START, END), that is when
+the time is greater or equal to START and is lesser than
+END.
+
+
COMMANDS consists of a sequence of one or more command
+specifications, separated by ",", relating to that interval. The
+syntax of a command specification is given by:
+
[FLAGS] TARGETCOMMANDARG
+
+
+
FLAGS is optional and specifies the type of events relating to
+the time interval which enable sending the specified command, and must
+be a non-null sequence of identifier flags separated by "+" or "|" and
+enclosed between "[" and "]".
+
+
The following flags are recognized:
+
+
‘enter’
+
The command is sent when the current frame timestamp enters the
+specified interval. In other words, the command is sent when the
+previous frame timestamp was not in the given interval, and the
+current is.
+
+
+
‘leave’
+
The command is sent when the current frame timestamp leaves the
+specified interval. In other words, the command is sent when the
+previous frame timestamp was in the given interval, and the
+current is not.
+
+
+
+
If FLAGS is not specified, a default value of [enter] is
+assumed.
+
+
TARGET specifies the target of the command, usually the name of
+the filter class or a specific filter instance name.
+
+
COMMAND specifies the name of the command for the target filter.
+
+
ARG is optional and specifies the optional list of argument for
+the given COMMAND.
+
+
Between one interval specification and another, whitespaces, or
+sequences of characters starting with # until the end of line,
+are ignored and can be used to annotate comments.
+
+
A simplified BNF description of the commands specification syntax
+follows:
+
+Specify a list of drawtext and hue commands in a file.
+
# show text in the interval 5-10
+5.0-10.0 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=hello world',
+ [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=';
+
+# desaturate the image in the interval 15-20
+15.0-20.0 [enter] hue s 0,
+ [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=nocolor',
+ [leave] hue s 1,
+ [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=color';
+
+# apply an exponential saturation fade-out effect, starting from time 25
+25 [enter] hue s exp(25-t)
+
+
+
A filtergraph allowing to read and process the above command list
+stored in a file ‘test.cmd’, can be specified with:
+
Set the timebase to use for the output frames timestamps.
+It is mainly useful for testing timebase configuration.
+
+
This filter accepts the following options:
+
+
+
‘expr, tb’
+
The expression which is evaluated into the output timebase.
+
+
+
+
+
The value for ‘tb’ is an arithmetic expression representing a
+rational. The expression can contain the constants "AVTB" (the default
+timebase), "intb" (the input timebase) and "sr" (the sample rate,
+audio only). Default value is "intb".
+
Convert input audio to a video output, representing the audio frequency
+spectrum.
+
+
The filter accepts the following options:
+
+
+
‘size, s’
+
Specify the video size for the output. For the syntax of this option, check
+the "Video size" section in the ffmpeg-utils manual. Default value is
+640x512.
+
+
+
‘slide’
+
Specify if the spectrum should slide along the window. Default value is
+0.
+
+
+
‘mode’
+
Specify display mode.
+
+
It accepts the following values:
+
+
‘combined’
+
all channels are displayed in the same row
+
+
‘separate’
+
all channels are displayed in separate rows
+
+
+
+
Default value is ‘combined’.
+
+
+
‘color’
+
Specify display color mode.
+
+
It accepts the following values:
+
+
‘channel’
+
each channel is displayed in a separate color
+
+
‘intensity’
+
each channel is is displayed using the same color scheme
+
+
+
+
Default value is ‘channel’.
+
+
+
‘scale’
+
Specify scale used for calculating intensity color values.
+
+
It accepts the following values:
+
+
‘lin’
+
linear
+
+
‘sqrt’
+
square root, default
+
+
‘cbrt’
+
cubic root
+
+
‘log’
+
logarithmic
+
+
+
+
Default value is ‘sqrt’.
+
+
+
‘saturation’
+
Set saturation modifier for displayed colors. Negative values provide
+alternative color scheme. 0 is no saturation at all.
+Saturation must be in [-10.0, 10.0] range.
+Default value is 1.
+
+
+
+
The usage is very similar to the showwaves filter; see the examples in that
+section.
+
Convert input audio to a video output, representing the samples waves.
+
+
The filter accepts the following options:
+
+
+
‘size, s’
+
Specify the video size for the output. For the syntax of this option, check
+the "Video size" section in the ffmpeg-utils manual. Default value
+is "600x240".
+
+
+
‘mode’
+
Set display mode.
+
+
Available values are:
+
+
‘point’
+
Draw a point for each sample.
+
+
+
‘line’
+
Draw a vertical line for each sample.
+
+
+
+
Default value is point.
+
+
+
‘n’
+
Set the number of samples which are printed on the same column. A
+larger value will decrease the frame rate. Must be a positive
+integer. This option can be set only if the value for rate
+is not explicitly specified.
+
+
+
‘rate, r’
+
Set the (approximate) output frame rate. This is done by setting the
+option n. Default value is "25".
+
The zmq and azmq filters work as a libzmq server, which
+receives messages sent through a network interface defined by the
+‘bind_address’ option.
+
+
The received message must be in the form:
+
TARGETCOMMAND [ARG]
+
+
+
TARGET specifies the target of the command, usually the name of
+the filter class or a specific filter instance name.
+
+
COMMAND specifies the name of the command for the target filter.
+
+
ARG is optional and specifies the optional argument list for the
+given COMMAND.
+
+
Upon reception, the message is processed and the corresponding command
+is injected into the filtergraph. Depending on the result, the filter
+will send a reply to the client, adopting the format:
+
Read audio and/or video stream(s) from a movie container.
+
+
This filter accepts the following options:
+
+
+
‘filename’
+
The name of the resource to read (not necessarily a file but also a device or a
+stream accessed through some protocol).
+
+
+
‘format_name, f’
+
Specifies the format assumed for the movie to read, and can be either
+the name of a container or an input device. If not specified the
+format is guessed from movie_name or by probing.
+
+
+
‘seek_point, sp’
+
Specifies the seek point in seconds, the frames will be output
+starting from this seek point, the parameter is evaluated with
+av_strtod so the numerical value may be suffixed by an IS
+postfix. Default value is "0".
+
+
+
‘streams, s’
+
Specifies the streams to read. Several streams can be specified,
+separated by "+". The source will then have as many outputs, in the
+same order. The syntax is explained in the “Stream specifiers”
+section in the ffmpeg manual. Two special names, "dv" and "da" specify
+respectively the default (best suited) video and audio stream. Default
+is "dv", or "da" if the filter is called as "amovie".
+
+
+
‘stream_index, si’
+
Specifies the index of the video stream to read. If the value is -1,
+the best suited video stream will be automatically selected. Default
+value is "-1". Deprecated. If the filter is called "amovie", it will select
+audio instead of video.
+
+
+
‘loop’
+
Specifies how many times to read the stream in sequence.
+If the value is less than 1, the stream will be read again and again.
+Default value is "1".
+
+
Note that when the movie is looped the source timestamps are not
+changed, so it will generate non monotonically increasing timestamps.
+
+
+
+
This filter allows to overlay a second video on top of main input of
+a filtergraph as shown in this graph:
+
+Read the first video stream and the audio stream with id 0x81 from
+dvd.vob; the video is connected to the pad named "video" and the audio is
+connected to the pad named "audio":
+
For details about the authorship, see the Git history of the project
+(git://source.ffmpeg.org/ffmpeg), e.g. by typing the command
+git log in the FFmpeg source directory, or browsing the
+online repository at http://source.ffmpeg.org.
+
+
Maintainers for the specific components are listed in the file
+‘MAINTAINERS’ in the source code tree.
+
All the numerical options, if not specified otherwise, accept in input
-a string representing a number, which may contain one of the
-International System number postfixes, for example ’K’, ’M’, ’G’.
-If ’i’ is appended after the postfix, powers of 2 are used instead of
-powers of 10. The ’B’ postfix multiplies the value for 8, and can be
-appended after another postfix or used alone. This allows using for
-example ’KB’, ’MiB’, ’G’ and ’B’ as postfix.
+
All the numerical options, if not specified otherwise, accept a string
+representing a number as input, which may be followed by one of the SI
+unit prefixes, for example: ’K’, ’M’, or ’G’.
+
+
If ’i’ is appended to the SI unit prefix, the complete prefix will be
+interpreted as a unit prefix for binary multiplies, which are based on
+powers of 1024 instead of powers of 1000. Appending ’B’ to the SI unit
+prefix multiplies the value by 8. This allows using, for example:
+’KB’, ’MiB’, ’G’ and ’B’ as number suffixes.
Options which do not take arguments are boolean options, and set the
corresponding value to true. They can be set to false by prefixing
-with "no" the option name, for example using "-nofoo" in the
-command line will set to false the boolean option with name "foo".
+the option name with "no". For example using "-nofoo"
+will set the boolean option with name "foo" to false.
Some options are applied per-stream, e.g. bitrate or codec. Stream specifiers
-are used to precisely specify which stream(s) does a given option belong to.
+are used to precisely specify which stream(s) a given option belongs to.
A stream specifier is a string generally appended to the option name and
-separated from it by a colon. E.g. -codec:a:1 ac3 option contains
-a:1 stream specifer, which matches the second audio stream. Therefore it
+separated from it by a colon. E.g. -codec:a:1 ac3 contains the
+a:1 stream specifier, which matches the second audio stream. Therefore, it
would select the ac3 codec for the second audio stream.
-
A stream specifier can match several stream, the option is then applied to all
+
A stream specifier can match several streams, so that the option is applied to all
of them. E.g. the stream specifier in -b:a 128k matches all audio
streams.
-
An empty stream specifier matches all streams, for example -codec copy
+
An empty stream specifier matches all streams. For example, -codec copy
or -codec: copy would copy all the streams without reencoding.
Possible forms of stream specifiers are:
@@ -385,29 +105,73 @@ or -codec: copy would copy all the streams without reencoding.
thread count for the second stream to 4.
‘stream_type[:stream_index]’
-
stream_type is one of: ’v’ for video, ’a’ for audio, ’s’ for subtitle,
-’d’ for data and ’t’ for attachments. If stream_index is given, then
-matches stream number stream_index of this type. Otherwise matches all
+
stream_type is one of following: ’v’ for video, ’a’ for audio, ’s’ for subtitle,
+’d’ for data, and ’t’ for attachments. If stream_index is given, then it matches
+stream number stream_index of this type. Otherwise, it matches all
streams of this type.
‘p:program_id[:stream_index]’
-
If stream_index is given, then matches stream number stream_index in
-program with id program_id. Otherwise matches all streams in this program.
+
If stream_index is given, then it matches the stream with number stream_index
+in the program with the id program_id. Otherwise, it matches all streams in the
+program.
+
Show help. An optional parameter may be specified to print help about a specific
+item. If no argument is specified, only basic (non advanced) tool
+options are shown.
+
Possible values of arg are:
+
+
‘long’
+
Print advanced tool options in addition to the basic tool options.
+
+
+
‘full’
+
Print complete list of options, including shared and private options
+for encoders, decoders, demuxers, muxers, filters, etc.
+
+
+
‘decoder=decoder_name’
+
Print detailed information about the decoder named decoder_name. Use the
+‘-decoders’ option to get a list of all decoders.
+
+
+
‘encoder=encoder_name’
+
Print detailed information about the encoder named encoder_name. Use the
+‘-encoders’ option to get a list of all encoders.
+
+
+
‘demuxer=demuxer_name’
+
Print detailed information about the demuxer named demuxer_name. Use the
+‘-formats’ option to get a list of all demuxers and muxers.
+
+
+
‘muxer=muxer_name’
+
Print detailed information about the muxer named muxer_name. Use the
+‘-formats’ option to get a list of all muxers and demuxers.
+
+
+
‘filter=filter_name’
+
Print detailed information about the filter name filter_name. Use the
+‘-filters’ option to get a list of all filters.
+
+
+
‘-version’
Show version.
@@ -416,42 +180,21 @@ program with id program_id. Otherwise matches all streams in this pro
‘-formats’
Show available formats.
-
The fields preceding the format names have the following meanings:
-
-
‘D’
-
Decoding available
-
-
‘E’
-
Encoding available
-
-
-
‘-codecs’
-
Show available codecs.
+
Show all codecs known to libavcodec.
+
+
Note that the term ’codec’ is used throughout this documentation as a shortcut
+for what is more correctly called a media bitstream format.
+
+
+
‘-decoders’
+
Show available decoders.
+
+
+
‘-encoders’
+
Show all available encoders.
-
The fields preceding the codec names have the following meanings:
-
-
‘D’
-
Decoding available
-
-
‘E’
-
Encoding available
-
-
‘V/A/S’
-
Video/audio/subtitle codec
-
-
‘S’
-
Codec supports slices
-
-
‘D’
-
Codec supports direct rendering
-
-
‘T’
-
Codec can handle input truncated at random locations instead of only at frame boundaries
-
-
-
‘-bsfs’
Show available bitstream filters.
@@ -473,18 +216,52 @@ program with id program_id. Otherwise matches all streams in this pro
Show available sample formats.
-
‘-loglevel loglevel | -v loglevel’
+
‘-layouts’
+
Show channel names and standard channel layouts.
+
Set the logging level used by the library.
+Adding "repeat+" indicates that repeated log output should not be compressed
+to the first line and the "Last message repeated n times" line will be
+omitted. "repeat" can also be used alone.
+If "repeat" is used alone, and with no prior loglevel set, the default
+loglevel will be used. If multiple loglevel parameters are given, using
+’repeat’ will not change the loglevel.
loglevel is a number or a string containing one of the following values:
‘quiet’
+
Show nothing at all; be silent.
+
‘panic’
+
Only show fatal errors which could lead the process to crash, such as
+and assert failure. This is not currently used for anything.
+
‘fatal’
+
Only show fatal errors. These are errors after which the process absolutely
+cannot continue after.
+
‘error’
+
Show all errors, including ones which can be recovered from.
+
‘warning’
+
Show all warnings and errors. Any message related to possibly
+incorrect or unexpected events will be shown.
+
‘info’
+
Show informative messages during processing. This is in addition to
+warnings and errors. This is the default value.
+
‘verbose’
+
Same as info, except more verbose.
+
‘debug’
+
Show everything, including debugging information.
+
By default the program logs to stderr, if coloring is supported by the
@@ -503,10 +280,92 @@ directory.
This file can be useful for bug reports.
It also implies -loglevel verbose.
-
Note: setting the environment variable FFREPORT to any value has the
-same effect.
+
Setting the environment variable FFREPORT to any value has the
+same effect. If the value is a ’:’-separated key=value sequence, these
+options will affect the report; options values must be escaped if they
+contain special characters or the options delimiter ’:’ (see the
+“Quoting and escaping” section in the ffmpeg-utils manual). The
+following option is recognized:
+
+
‘file’
+
set the file name to use for the report; %p is expanded to the name
+of the program, %t is expanded to a timestamp, %% is expanded
+to a plain %
+
+
+
+
Errors in parsing the environment variable are not fatal, and will not
+appear in the report.
+
‘-cpuflags flags (global)’
+
Allows setting and clearing cpu flags. This option is intended
+for testing. Do not use it unless you know what you’re doing.
+
Set OpenCL environment options. This option is only available when
+FFmpeg has been compiled with --enable-opencl.
+
+
options must be a list of key=value option pairs
+separated by ’:’. See the “OpenCL Options” section in the
+ffmpeg-utils manual for the list of supported options.
+
@@ -533,14 +392,15 @@ muxer:
ffmpeg -i input.flac -id3v2_version 3 out.mp3
-
All codec AVOptions are obviously per-stream, so the chapter on stream
-specifiers applies to them
+
All codec AVOptions are per-stream, and thus a stream specifier
+should be attached to them.
-
Note ‘-nooption’ syntax cannot be used for boolean AVOptions,
-use ‘-option 0’/‘-option 1’.
+
Note: the ‘-nooption’ syntax cannot be used for boolean
+AVOptions, use ‘-option 0’/‘-option 1’.
-
Note2 old undocumented way of specifying per-stream AVOptions by prepending
-v/a/s to the options name is now obsolete and will be removed soon.
+
Note: the old undocumented way of specifying per-stream AVOptions by
+prepending v/a/s to the options name is now obsolete and will be
+removed soon.
@@ -606,11 +466,23 @@ Available values for mode are:
pressing the key <w>.
-
‘-vf filter_graph’
-
filter_graph is a description of the filter graph to apply to
-the input video.
+
‘-vf filtergraph’
+
Create the filtergraph specified by filtergraph and use it to
+filter the video stream.
+
+
filtergraph is a description of the filtergraph to apply to
+the stream, and must have a single video input and a single video
+output. In the filtergraph, the input is associated to the label
+in, and the output to the label out. See the
+ffmpeg-filters manual for more information about the filtergraph
+syntax.
+
+
+
‘-af filtergraph’
+
filtergraph is a description of the filtergraph to apply to
+the input audio.
Use the option "-filters" to show all the available filters (including
-also sources and sinks).
+sources and sinks).
‘-i input_file’
@@ -624,11 +496,15 @@ also sources and sinks).
‘-pix_fmt format’
Set pixel format.
This option has been deprecated in favor of private options, try -pixel_format.
-
+
+
‘-stats’
-
Show the stream duration, the codec parameters, the current position in
-the stream and the audio/video synchronisation drift.
-
+
Print several playback statistics, in particular show the stream
+duration, the codec parameters, the current position in the stream and
+the audio/video synchronisation drift. It is on by default, to
+explicitly disable it you need to specify -nostats.
+
+
‘-bug’
Work around bugs.
@@ -679,9 +555,24 @@ selected, if it is negative the subtitle rendering is disabled.
‘-exitonmousedown’
Exit if any mouse button is pressed.
-
-
‘-codec:stream_type’
-
Force a specific decoder implementation
+
+
+
‘-codec:media_specifiercodec_name’
+
Force a specific decoder implementation for the stream identified by
+media_specifier, which can assume the values a (audio),
+v (video), and s subtitle.
+
+
+
‘-acodec codec_name’
+
Force a specific audio decoder.
+
+
+
‘-vcodec codec_name’
+
Force a specific video decoder.
+
+
+
‘-scodec codec_name’
+
Force a specific subtitle decoder.
@@ -702,7 +593,7 @@ selected, if it is negative the subtitle rendering is disabled.
<a>
-
Cycle audio channel.
+
Cycle audio channel in the curret program.
<v>
@@ -710,7 +601,11 @@ selected, if it is negative the subtitle rendering is disabled.
<t>
-
Cycle subtitle channel.
+
Cycle subtitle channel in the current program.
+
+
+
<c>
+
Cycle program.
<w>
@@ -736,5516 +631,36 @@ selected, if it is negative the subtitle rendering is disabled.
-
-
When evaluating an arithmetic expression, FFmpeg uses an internal
-formula evaluator, implemented through the ‘libavutil/eval.h’
-interface.
-
-
An expression may contain unary, binary operators, constants, and
-functions.
-
-
Two expressions expr1 and expr2 can be combined to form
-another expression "expr1;expr2".
-expr1 and expr2 are evaluated in turn, and the new
-expression evaluates to the value of expr2.
-
-
The following binary operators are available: +, -,
-*, /, ^.
-
-
The following unary operators are available: +, -.
-
-
The following functions are available:
-
-
‘sinh(x)’
-
‘cosh(x)’
-
‘tanh(x)’
-
‘sin(x)’
-
‘cos(x)’
-
‘tan(x)’
-
‘atan(x)’
-
‘asin(x)’
-
‘acos(x)’
-
‘exp(x)’
-
‘log(x)’
-
‘abs(x)’
-
‘squish(x)’
-
‘gauss(x)’
-
‘isnan(x)’
-
Return 1.0 if x is NAN, 0.0 otherwise.
-
-
-
‘mod(x, y)’
-
‘max(x, y)’
-
‘min(x, y)’
-
‘eq(x, y)’
-
‘gte(x, y)’
-
‘gt(x, y)’
-
‘lte(x, y)’
-
‘lt(x, y)’
-
‘st(var, expr)’
-
Allow to store the value of the expression expr in an internal
-variable. var specifies the number of the variable where to
-store the value, and it is a value ranging from 0 to 9. The function
-returns the value stored in the internal variable.
-Note, Variables are currently not shared between expressions.
-
-
-
‘ld(var)’
-
Allow to load the value of the internal variable with number
-var, which was previously stored with st(var, expr).
-The function returns the loaded value.
-
-
-
‘while(cond, expr)’
-
Evaluate expression expr while the expression cond is
-non-zero, and returns the value of the last expr evaluation, or
-NAN if cond was always false.
-
-
-
‘ceil(expr)’
-
Round the value of expression expr upwards to the nearest
-integer. For example, "ceil(1.5)" is "2.0".
-
-
-
‘floor(expr)’
-
Round the value of expression expr downwards to the nearest
-integer. For example, "floor(-1.5)" is "-2.0".
-
-
-
‘trunc(expr)’
-
Round the value of expression expr towards zero to the nearest
-integer. For example, "trunc(-1.5)" is "-1.0".
-
-
-
‘sqrt(expr)’
-
Compute the square root of expr. This is equivalent to
-"(expr)^.5".
-
-
-
‘not(expr)’
-
Return 1.0 if expr is zero, 0.0 otherwise.
-
-
-
‘pow(x, y)’
-
Compute the power of x elevated y, it is equivalent to
-"(x)^(y)".
-
-
-
‘random(x)’
-
Return a pseudo random value between 0.0 and 1.0. x is the index of the
-internal variable which will be used to save the seed/state.
-
-
-
‘hypot(x, y)’
-
This function is similar to the C function with the same name; it returns
-"sqrt(x*x + y*y)", the length of the hypotenuse of a
-right triangle with sides of length x and y, or the distance of the
-point (x, y) from the origin.
-
-
-
‘gcd(x, y)’
-
Return the greatest common divisor of x and y. If both x and
-y are 0 or either or both are less than zero then behavior is undefined.
-
-
-
‘if(x, y)’
-
Evaluate x, and if the result is non-zero return the result of
-the evaluation of y, return 0 otherwise.
-
-
-
‘ifnot(x, y)’
-
Evaluate x, and if the result is zero return the result of the
-evaluation of y, return 0 otherwise.
-
-
-
-
The following constants are available:
-
-
‘PI’
-
area of the unit disc, approximately 3.14
-
-
‘E’
-
exp(1) (Euler’s number), approximately 2.718
-
-
‘PHI’
-
golden ratio (1+sqrt(5))/2, approximately 1.618
-
-
-
-
Assuming that an expression is considered "true" if it has a non-zero
-value, note that:
-
-
* works like AND
-
-
+ works like OR
-
-
and the construct:
-
if A then B else C
-
-
is equivalent to
-
if(A,B) + ifnot(A,C)
-
-
-
In your C code, you can extend the list of unary and binary functions,
-and define recognized constants, so that they are available for your
-expressions.
-
-
The evaluator also recognizes the International System number
-postfixes. If ’i’ is appended after the postfix, powers of 2 are used
-instead of powers of 10. The ’B’ postfix multiplies the value for 8,
-and can be appended after another postfix or used alone. This allows
-using for example ’KB’, ’MiB’, ’G’ and ’B’ as postfix.
-
-
Follows the list of available International System postfixes, with
-indication of the corresponding powers of 10 and of 2.
-
Decoders are configured elements in FFmpeg which allow the decoding of
-multimedia streams.
-
-
When you configure your FFmpeg build, all the supported native decoders
-are enabled by default. Decoders requiring an external library must be enabled
-manually via the corresponding --enable-lib option. You can list all
-available decoders using the configure option --list-decoders.
-
-
You can disable all the decoders with the configure option
---disable-decoders and selectively enable / disable single decoders
-with the options --enable-decoder=DECODER /
---disable-decoder=DECODER.
-
-
The option -codecs of the ff* tools will display the list of
-enabled decoders.
-
This decoder generates wave patterns according to predefined sequences. Its
-use is purely internal and the format of the data it accepts is not publicly
-documented.
-
Demuxers are configured elements in FFmpeg which allow to read the
-multimedia streams from a particular type of file.
-
-
When you configure your FFmpeg build, all the supported demuxers
-are enabled by default. You can list all available ones using the
-configure option "–list-demuxers".
-
-
You can disable all the demuxers using the configure option
-"–disable-demuxers", and selectively enable a single demuxer with
-the option "–enable-demuxer=DEMUXER", or disable it
-with the option "–disable-demuxer=DEMUXER".
-
-
The option "-formats" of the ff* tools will display the list of
-enabled demuxers.
-
-
The description of some of the currently available demuxers follows.
-
This demuxer reads from a list of image files specified by a pattern.
-
-
The pattern may contain the string "%d" or "%0Nd", which
-specifies the position of the characters representing a sequential
-number in each filename matched by the pattern. If the form
-"%d0Nd" is used, the string representing the number in each
-filename is 0-padded and N is the total number of 0-padded
-digits representing the number. The literal character ’%’ can be
-specified in the pattern with the string "%%".
-
-
If the pattern contains "%d" or "%0Nd", the first filename of
-the file list specified by the pattern must contain a number
-inclusively contained between 0 and 4, all the following numbers must
-be sequential. This limitation may be hopefully fixed.
-
-
The pattern may contain a suffix which is used to automatically
-determine the format of the images contained in the files.
-
-
For example the pattern "img-%03d.bmp" will match a sequence of
-filenames of the form ‘img-001.bmp’, ‘img-002.bmp’, ...,
-‘img-010.bmp’, etc.; the pattern "i%%m%%g-%d.jpg" will match a
-sequence of filenames of the form ‘i%m%g-1.jpg’,
-‘i%m%g-2.jpg’, ..., ‘i%m%g-10.jpg’, etc.
-
-
The size, the pixel format, and the format of each image must be the
-same for all the files in the sequence.
-
-
The following example shows how to use ffmpeg for creating a
-video from the images in the file sequence ‘img-001.jpeg’,
-‘img-002.jpeg’, ..., assuming an input frame rate of 10 frames per
-second:
-
ffmpeg -i 'img-%03d.jpeg' -r 10 out.mkv
-
-
-
Note that the pattern must not necessarily contain "%d" or
-"%0Nd", for example to convert a single image file
-‘img.jpeg’ you can employ the command:
-
This demuxer presents all AVStreams from all variant streams.
-The id field is set to the bitrate variant index number. By setting
-the discard flags on AVStreams (by pressing ’a’ or ’v’ in ffplay),
-the caller can decide which variant streams to actually receive.
-The total bitrate of the variant that the stream belongs to is
-available in a metadata key named "variant_bitrate".
-
This demuxer reads the script language used by SBaGen
-http://uazu.net/sbagen/ to generate binaural beats sessions. A SBG
-script looks like that:
-
-SE
-a: 300-2.5/3 440+4.5/0
-b: 300-2.5/0 440+4.5/3
-off: -
-NOW == a
-+0:07:00 == b
-+0:14:00 == a
-+0:21:00 == b
-+0:30:00 off
-
-
-
A SBG script can mix absolute and relative timestamps. If the script uses
-either only absolute timestamps (including the script start time) or only
-relative ones, then its layout is fixed, and the conversion is
-straightforward. On the other hand, if the script mixes both kind of
-timestamps, then the NOW reference for relative timestamps will be
-taken from the current time of day at the time the script is read, and the
-script layout will be frozen according to that reference. That means that if
-the script is directly played, the actual times will match the absolute
-timestamps up to the sound controller’s clock accuracy, but if the user
-somehow pauses the playback or seeks, all times will be shifted accordingly.
-
Muxers are configured elements in FFmpeg which allow writing
-multimedia streams to a particular type of file.
-
-
When you configure your FFmpeg build, all the supported muxers
-are enabled by default. You can list all available muxers using the
-configure option --list-muxers.
-
-
You can disable all the muxers with the configure option
---disable-muxers and selectively enable / disable single muxers
-with the options --enable-muxer=MUXER /
---disable-muxer=MUXER.
-
-
The option -formats of the ff* tools will display the list of
-enabled muxers.
-
-
A description of some of the currently available muxers follows.
-
This muxer computes and prints the Adler-32 CRC of all the input audio
-and video frames. By default audio frames are converted to signed
-16-bit raw audio and video frames to raw video before computing the
-CRC.
-
-
The output of the muxer consists of a single line of the form:
-CRC=0xCRC, where CRC is a hexadecimal number 0-padded to
-8 digits containing the CRC for all the decoded input frames.
-
-
For example to compute the CRC of the input, and store it in the file
-‘out.crc’:
-
ffmpeg -i INPUT -f crc out.crc
-
-
-
You can print the CRC to stdout with the command:
-
ffmpeg -i INPUT -f crc -
-
-
-
You can select the output format of each frame with ffmpeg by
-specifying the audio and video codec and format. For example to
-compute the CRC of the input audio converted to PCM unsigned 8-bit
-and the input video converted to MPEG-2 video, use the command:
-
This muxer computes and prints the Adler-32 CRC for each decoded audio
-and video frame. By default audio frames are converted to signed
-16-bit raw audio and video frames to raw video before computing the
-CRC.
-
-
The output of the muxer consists of a line for each audio and video
-frame of the form: stream_index, frame_dts,
-frame_size, 0xCRC, where CRC is a hexadecimal
-number 0-padded to 8 digits containing the CRC of the decoded frame.
-
-
For example to compute the CRC of each decoded frame in the input, and
-store it in the file ‘out.crc’:
-
ffmpeg -i INPUT -f framecrc out.crc
-
-
-
You can print the CRC of each decoded frame to stdout with the command:
-
ffmpeg -i INPUT -f framecrc -
-
-
-
You can select the output format of each frame with ffmpeg by
-specifying the audio and video codec and format. For example, to
-compute the CRC of each decoded input audio frame converted to PCM
-unsigned 8-bit and of each decoded input video frame converted to
-MPEG-2 video, use the command:
-
The image file muxer writes video frames to image files.
-
-
The output filenames are specified by a pattern, which can be used to
-produce sequentially numbered series of files.
-The pattern may contain the string "%d" or "%0Nd", this string
-specifies the position of the characters representing a numbering in
-the filenames. If the form "%0Nd" is used, the string
-representing the number in each filename is 0-padded to N
-digits. The literal character ’%’ can be specified in the pattern with
-the string "%%".
-
-
If the pattern contains "%d" or "%0Nd", the first filename of
-the file list specified will contain the number 1, all the following
-numbers will be sequential.
-
-
The pattern may contain a suffix which is used to automatically
-determine the format of the image files to write.
-
-
For example the pattern "img-%03d.bmp" will specify a sequence of
-filenames of the form ‘img-001.bmp’, ‘img-002.bmp’, ...,
-‘img-010.bmp’, etc.
-The pattern "img%%-%d.jpg" will specify a sequence of filenames of the
-form ‘img%-1.jpg’, ‘img%-2.jpg’, ..., ‘img%-10.jpg’,
-etc.
-
-
The following example shows how to use ffmpeg for creating a
-sequence of files ‘img-001.jpeg’, ‘img-002.jpeg’, ...,
-taking one image every second from the input video:
-
Note that with ffmpeg, if the format is not specified with the
--f option and the output filename specifies an image file
-format, the image2 muxer is automatically selected, so the previous
-command can be written as:
-
ffmpeg -i in.avi -vsync 1 -r 1 'img-%03d.jpeg'
-
-
-
Note also that the pattern must not necessarily contain "%d" or
-"%0Nd", for example to create a single image file
-‘img.jpeg’ from the input video you can employ the command:
-
ffmpeg -i in.avi -f image2 -frames:v 1 img.jpeg
-
-
-
The image muxer supports the .Y.U.V image file format. This format is
-special in that that each image frame consists of three files, for
-each of the YUV420P components. To read or write this image file format,
-specify the name of the ’.Y’ file. The muxer will automatically open the
-’.U’ and ’.V’ files as required.
-
Reserves space for the moov atom at the beginning of the file instead of placing the
-moov atom at the end. If the space reserved is insufficient, muxing will fail.
-
This muxer implements ISO 13818-1 and part of ETSI EN 300 468.
-
-
The muxer options are:
-
-
-
‘-mpegts_original_network_id number’
-
Set the original_network_id (default 0x0001). This is unique identifier
-of a network in DVB. Its main use is in the unique identification of a
-service through the path Original_Network_ID, Transport_Stream_ID.
-
-
‘-mpegts_transport_stream_id number’
-
Set the transport_stream_id (default 0x0001). This identifies a
-transponder in DVB.
-
-
‘-mpegts_service_id number’
-
Set the service_id (default 0x0001) also known as program in DVB.
-
-
‘-mpegts_pmt_start_pid number’
-
Set the first PID for PMT (default 0x1000, max 0x1f00).
-
-
‘-mpegts_start_pid number’
-
Set the first PID for data packets (default 0x0100, max 0x0f00).
-
-
-
-
The recognized metadata settings in mpegts muxer are service_provider
-and service_name. If they are not set the default for
-service_provider is "FFmpeg" and the default for
-service_name is "Service01".
-
The segmenter muxer outputs streams to a number of separate files of nearly
-fixed duration. Output filename pattern can be set in a fashion similar to
-image2.
-
-
Every segment starts with a video keyframe, if a video stream is present.
-The segment muxer works best with a single constant frame rate video.
-
-
Optionally it can generate a flat list of the created segments, one segment
-per line.
-
-
-
‘segment_format format’
-
Override the inner container format, by default it is guessed by the filename
-extension.
-
-
‘segment_time t’
-
Set segment duration to t seconds.
-
-
‘segment_list name’
-
Generate also a listfile named name.
-
-
‘segment_list_size size’
-
Overwrite the listfile once it reaches size entries.
-
Input devices are configured elements in FFmpeg which allow to access
-the data coming from a multimedia device attached to your system.
-
-
When you configure your FFmpeg build, all the supported input devices
-are enabled by default. You can list all available ones using the
-configure option "–list-indevs".
-
-
You can disable all the input devices using the configure option
-"–disable-indevs", and selectively enable an input device using the
-option "–enable-indev=INDEV", or you can disable a particular
-input device using the option "–disable-indev=INDEV".
-
-
The option "-formats" of the ff* tools will display the list of
-supported input devices (amongst the demuxers).
-
-
A description of the currently available input devices follows.
-
The Linux framebuffer is a graphic hardware-independent abstraction
-layer to show graphics on a computer monitor, typically on the
-console. It is accessed through a file device node, usually
-‘/dev/fb0’.
-
-
For more detailed information read the file
-Documentation/fb/framebuffer.txt included in the Linux source tree.
-
-
To record from the framebuffer device ‘/dev/fb0’ with
-ffmpeg:
-
ffmpeg -f fbdev -r 10 -i /dev/fb0 out.avi
-
-
-
You can take a single screenshot image with the command:
-
To enable this input device during configuration you need libjack
-installed on your system.
-
-
A JACK input device creates one or more JACK writable clients, one for
-each audio channel, with name client_name:input_N, where
-client_name is the name provided by the application, and N
-is a number which identifies the channel.
-Each writable client will send the acquired data to the FFmpeg input
-device.
-
-
Once you have created one or more JACK readable clients, you need to
-connect them to one or more JACK writable clients.
-
-
To connect or disconnect JACK clients you can use the jack_connect
-and jack_disconnect programs, or do it through a graphical interface,
-for example with qjackctl.
-
-
To list the JACK clients and their properties you can invoke the command
-jack_lsp.
-
-
Follows an example which shows how to capture a JACK readable client
-with ffmpeg.
-
# Create a JACK writable client with name "ffmpeg".
-$ ffmpeg -f jack -i ffmpeg -y out.wav
-
-# Start the sample jack_metro readable client.
-$ jack_metro -b 120 -d 0.2 -f 4000
-
-# List the current JACK clients.
-$ jack_lsp -c
-system:capture_1
-system:capture_2
-system:playback_1
-system:playback_2
-ffmpeg:input_1
-metro:120_bpm
-
-# Connect metro to the ffmpeg writable client.
-$ jack_connect metro:120_bpm ffmpeg:input_1
-
This input device reads data from the open output pads of a libavfilter
-filtergraph.
-
-
For each filtergraph open output, the input device will create a
-corresponding stream which is mapped to the generated output. Currently
-only video data is supported. The filtergraph is specified through the
-option ‘graph’.
-
Specify the filtergraph to use as input. Each video open output must be
-labelled by a unique string of the form "outN", where N is a
-number starting from 0 corresponding to the mapped input stream
-generated by the device.
-The first unlabelled output is automatically assigned to the "out0"
-label, but all the others need to be specified explicitly.
-
-
If not specified defaults to the filename specified for the input
-device.
-
The OpenAL input device provides audio capture on all systems with a
-working OpenAL 1.1 implementation.
-
-
To enable this input device during configuration, you need OpenAL
-headers and libraries installed on your system, and need to configure
-FFmpeg with --enable-openal.
-
-
OpenAL headers and libraries should be provided as part of your OpenAL
-implementation, or as an additional download (an SDK). Depending on your
-installation you may need to specify additional flags via the
---extra-cflags and --extra-ldflags for allowing the build
-system to locate the OpenAL headers and libraries.
-
-
An incomplete list of OpenAL implementations follows:
-
-
-
Creative
-
The official Windows implementation, providing hardware acceleration
-with supported devices and software fallback.
-See http://openal.org/.
-
-
OpenAL Soft
-
Portable, open source (LGPL) software implementation. Includes
-backends for the most common sound APIs on the Windows, Linux,
-Solaris, and BSD operating systems.
-See http://kcat.strangesoft.net/openal.html.
-
This device allows to capture from an audio input device handled
-through OpenAL.
-
-
You need to specify the name of the device to capture in the provided
-filename. If the empty string is provided, the device will
-automatically select the default device. You can get the list of the
-supported devices by using the option list_devices.
-
Video4Linux and Video4Linux2 input video devices.
-
-
The name of the device to grab is a file device node, usually Linux
-systems tend to automatically create such nodes when the device
-(e.g. an USB webcam) is plugged into the system, and has a name of the
-kind ‘/dev/videoN’, where N is a number associated to
-the device.
-
-
Video4Linux and Video4Linux2 devices only support a limited set of
-widthxheight sizes and framerates. You can check which are
-supported for example with the command dov4l for Video4Linux
-devices and using -list_formats all for Video4Linux2 devices.
-
-
If the size for the device is set to 0x0, the input device will
-try to auto-detect the size to use.
-Only for the video4linux2 device, if the frame rate is set to 0/0 the
-input device will use the frame rate value already set in the driver.
-
-
Video4Linux support is deprecated since Linux 2.6.30, and will be
-dropped in later versions.
-
-
Note that if FFmpeg is build with v4l-utils support ("–enable-libv4l2"
-option), it will always be used.
-
-
Follow some usage examples of the video4linux devices with the ff*
-tools.
-
# Grab and show the input of a video4linux device, frame rate is set
-# to the default of 25/1.
-ffplay -s 320x240 -f video4linux /dev/video0
-
-# Grab and show the input of a video4linux2 device, auto-adjust size.
-ffplay -f video4linux2 /dev/video0
-
-# Grab and record the input of a video4linux2 device, auto-adjust size,
-# frame rate value defaults to 0/0 so it is read from the video4linux2
-# driver.
-ffmpeg -f video4linux2 -i /dev/video0 out.mpeg
-
-
-
"v4l" and "v4l2" can be used as aliases for the respective "video4linux" and
-"video4linux2".
-
The filename passed as input is the capture driver number, ranging from
-0 to 9. You may use "list" as filename to print a list of drivers. Any
-other filename will be interpreted as device number 0.
-
hostname:display_number.screen_number specifies the
-X11 display name of the screen to grab from. hostname can be
-omitted, and defaults to "localhost". The environment variable
-DISPLAY contains the default display name.
-
-
x_offset and y_offset specify the offsets of the grabbed
-area with respect to the top-left border of the X11 screen. They
-default to 0.
-
-
Check the X11 documentation (e.g. man X) for more detailed information.
-
-
Use the dpyinfo program for getting basic information about the
-properties of your X11 display (e.g. grep for "name" or "dimensions").
-
When it is specified with "centered", the grabbing region follows the mouse
-pointer and keeps the pointer at the center of region; otherwise, the region
-follows only when the mouse pointer reaches within PIXELS (greater than
-zero) to the edge of region.
-
-
For example:
-
ffmpeg -f x11grab -follow_mouse centered -r 25 -s cif -i :0.0 out.mpg
-
-# Follows only when the mouse pointer reaches within 100 pixels to edge
-ffmpeg -f x11grab -follow_mouse 100 -r 25 -s cif -i :0.0 out.mpg
-
If show_region AVOption is specified with 1, then the grabbing
-region will be indicated on screen. With this option, it’s easy to know what is
-being grabbed if only a portion of the screen is grabbed.
-
Output devices are configured elements in FFmpeg which allow to write
-multimedia data to an output device attached to your system.
-
-
When you configure your FFmpeg build, all the supported output devices
-are enabled by default. You can list all available ones using the
-configure option "–list-outdevs".
-
-
You can disable all the output devices using the configure option
-"–disable-outdevs", and selectively enable an output device using the
-option "–enable-outdev=OUTDEV", or you can disable a particular
-input device using the option "–disable-outdev=OUTDEV".
-
-
The option "-formats" of the ff* tools will display the list of
-enabled output devices (amongst the muxers).
-
-
A description of the currently available output devices follows.
-
This output devices allows to show a video stream in an SDL
-window. Only one SDL window is allowed per application, so you can
-have only one instance of this output device in an application.
-
-
To enable this output device you need libsdl installed on your system
-when configuring your build.
-
Set the SDL window title, if not specified default to the filename
-specified for the output device.
-
-
-
‘icon_title’
-
Set the name of the iconified SDL window, if not specified it is set
-to the same value of window_title.
-
-
-
‘window_size’
-
Set the SDL window size, can be a string of the form
-widthxheight or a video size abbreviation.
-If not specified it defaults to the size of the input video.
-
Protocols are configured elements in FFmpeg which allow to access
-resources which require the use of a particular protocol.
-
-
When you configure your FFmpeg build, all the supported protocols are
-enabled by default. You can list all available ones using the
-configure option "–list-protocols".
-
-
You can disable all the protocols using the configure option
-"–disable-protocols", and selectively enable a protocol using the
-option "–enable-protocol=PROTOCOL", or you can disable a
-particular protocol using the option
-"–disable-protocol=PROTOCOL".
-
-
The option "-protocols" of the ff* tools will display the list of
-supported protocols.
-
-
A description of the currently available protocols follows.
-
Read Apple HTTP Live Streaming compliant segmented stream as
-a uniform one. The M3U8 playlists describing the segments can be
-remote HTTP resources or local files, accessed using the standard
-file protocol.
-HTTP is default, specific protocol can be declared by specifying
-"+proto" after the applehttp URI scheme name, where proto
-is either "file" or "http".
-
Computes the MD5 hash of the data to be written, and on close writes
-this to the designated output or stdout if none is specified. It can
-be used to test muxers without writing an actual file.
-
-
Some examples follow.
-
# Write the MD5 hash of the encoded AVI file to the file output.avi.md5.
-ffmpeg -i input.flv -f avi -y md5:output.avi.md5
-
-# Write the MD5 hash of the encoded AVI file to stdout.
-ffmpeg -i input.flv -f avi -y md5:
-
-
-
Note that some formats (typically MOV) require the output protocol to
-be seekable, so they will fail with the MD5 output protocol.
-
number is the number corresponding to the file descriptor of the
-pipe (e.g. 0 for stdin, 1 for stdout, 2 for stderr). If number
-is not specified, by default the stdout file descriptor will be used
-for writing, stdin for reading.
-
-
For example to read from stdin with ffmpeg:
-
cat test.wav | ffmpeg -i pipe:0
-# ...this is the same as...
-cat test.wav | ffmpeg -i pipe:
-
-
-
For writing to stdout with ffmpeg:
-
ffmpeg -i test.wav -f avi pipe:1 | cat > test.avi
-# ...this is the same as...
-ffmpeg -i test.wav -f avi pipe: | cat > test.avi
-
-
-
Note that some formats (typically MOV), require the output protocol to
-be seekable, so they will fail with the pipe output protocol.
-
The Real-Time Messaging Protocol (RTMP) is used for streaming multimedia
-content across a TCP/IP network.
-
-
The required syntax is:
-
rtmp://server[:port][/app][/playpath]
-
-
-
The accepted parameters are:
-
-
‘server’
-
The address of the RTMP server.
-
-
-
‘port’
-
The number of the TCP port to use (by default is 1935).
-
-
-
‘app’
-
It is the name of the application to access. It usually corresponds to
-the path where the application is installed on the RTMP server
-(e.g. ‘/ondemand/’, ‘/flash/live/’, etc.).
-
-
-
‘playpath’
-
It is the path or name of the resource to play with reference to the
-application specified in app, may be prefixed by "mp4:".
-
-
-
-
-
For example to read with ffplay a multimedia resource named
-"sample" from the application "vod" from an RTMP server "myserver":
-
Real-Time Messaging Protocol and its variants supported through
-librtmp.
-
-
Requires the presence of the librtmp headers and library during
-configuration. You need to explicitly configure the build with
-"–enable-librtmp". If enabled this will replace the native RTMP
-protocol.
-
-
This protocol provides most client functions and a few server
-functions needed to support RTMP, RTMP tunneled in HTTP (RTMPT),
-encrypted RTMP (RTMPE), RTMP over SSL/TLS (RTMPS) and tunneled
-variants of these encrypted types (RTMPTE, RTMPTS).
-
where rtmp_proto is one of the strings "rtmp", "rtmpt", "rtmpe",
-"rtmps", "rtmpte", "rtmpts" corresponding to each RTMP variant, and
-server, port, app and playpath have the same
-meaning as specified for the RTMP native protocol.
-options contains a list of space-separated options of the form
-key=val.
-
-
See the librtmp manual page (man 3 librtmp) for more information.
-
-
For example, to stream a file in real-time to an RTMP server using
-ffmpeg:
-
RTSP is not technically a protocol handler in libavformat, it is a demuxer
-and muxer. The demuxer supports both normal RTSP (with data transferred
-over RTP; this is used by e.g. Apple and Microsoft) and Real-RTSP (with
-data transferred over RDT).
-
-
The muxer can be used to send a stream using RTSP ANNOUNCE to a server
-supporting it (currently Darwin Streaming Server and Mischa Spiegelmock’s
-RTSP server).
-
-
The required syntax for a RTSP url is:
-
rtsp://hostname[:port]/path
-
-
-
The following options (set on the ffmpeg/ffplay command
-line, or set in code via AVOptions or in avformat_open_input),
-are supported:
-
-
Flags for rtsp_transport:
-
-
-
‘udp’
-
Use UDP as lower transport protocol.
-
-
-
‘tcp’
-
Use TCP (interleaving within the RTSP control channel) as lower
-transport protocol.
-
-
-
‘udp_multicast’
-
Use UDP multicast as lower transport protocol.
-
-
-
‘http’
-
Use HTTP tunneling as lower transport protocol, which is useful for
-passing proxies.
-
-
-
-
Multiple lower transport protocols may be specified, in that case they are
-tried one at a time (if the setup of one fails, the next one is tried).
-For the muxer, only the tcp and udp options are supported.
-
-
Flags for rtsp_flags:
-
-
-
‘filter_src’
-
Accept packets only from negotiated peer address and port.
-
-
-
-
When receiving data over UDP, the demuxer tries to reorder received packets
-(since they may arrive out of order, or packets may get lost totally). In
-order for this to be enabled, a maximum delay must be specified in the
-max_delay field of AVFormatContext.
-
-
When watching multi-bitrate Real-RTSP streams with ffplay, the
-streams to display can be chosen with -vstn and
--astn for video and audio respectively, and can be switched
-on the fly by pressing v and a.
-
-
Example command lines:
-
-
To watch a stream over UDP, with a max reordering delay of 0.5 seconds:
-
Session Announcement Protocol (RFC 2974). This is not technically a
-protocol handler in libavformat, it is a muxer and demuxer.
-It is used for signalling of RTP streams, by announcing the SDP for the
-streams regularly on a separate port.
-
The RTP packets are sent to destination on port port,
-or to port 5004 if no port is specified.
-options is a &-separated list. The following options
-are supported:
-
-
-
‘announce_addr=address’
-
Specify the destination IP address for sending the announcements to.
-If omitted, the announcements are sent to the commonly used SAP
-announcement multicast address 224.2.127.254 (sap.mcast.net), or
-ff0e::2:7ffe if destination is an IPv6 address.
-
-
-
‘announce_port=port’
-
Specify the port to send the announcements on, defaults to
-9875 if not specified.
-
-
-
‘ttl=ttl’
-
Specify the time to live value for the announcements and RTP packets,
-defaults to 255.
-
-
-
‘same_port=0|1’
-
If set to 1, send all RTP streams on the same port pair. If zero (the
-default), all streams are sent on unique ports, with each stream on a
-port 2 numbers higher than the previous.
-VLC/Live555 requires this to be set to 1, to be able to receive the stream.
-The RTP stack in libavformat for receiving requires all streams to be sent
-on unique ports.
-
-
-
-
Example command lines follow.
-
-
To broadcast a stream on the local subnet, for watching in VLC:
-
-
ffmpeg -re -i input -f sap sap://224.0.0.255?same_port=1
-
-
-
Similarly, for watching in ffplay:
-
-
ffmpeg -re -i input -f sap sap://224.0.0.255
-
-
-
And for watching in ffplay, over IPv6:
-
-
ffmpeg -re -i input -f sap sap://[ff0e::1:2:3:4]
-
The syntax for a SAP url given to the demuxer is:
-
sap://[address][:port]
-
-
-
address is the multicast address to listen for announcements on,
-if omitted, the default 224.2.127.254 (sap.mcast.net) is used. port
-is the port that is listened on, 9875 if omitted.
-
-
The demuxers listens for announcements on the given address and port.
-Once an announcement is received, it tries to receive that particular stream.
-
-
Example command lines follow.
-
-
To play back the first stream announced on the normal SAP multicast address:
-
-
ffplay sap://
-
-
-
To play back the first stream announced on one the default IPv6 SAP multicast address:
-
options contains a list of &-seperated options of the form key=val.
-Follow the list of supported options.
-
-
-
‘buffer_size=size’
-
set the UDP buffer size in bytes
-
-
-
‘localport=port’
-
override the local UDP port to bind with
-
-
-
‘localaddr=addr’
-
Choose the local IP address. This is useful e.g. if sending multicast
-and the host has multiple interfaces, where the user can choose
-which interface to send on by specifying the IP address of that interface.
-
-
-
‘pkt_size=size’
-
set the size in bytes of UDP packets
-
-
-
‘reuse=1|0’
-
explicitly allow or disallow reusing UDP sockets
-
-
-
‘ttl=ttl’
-
set the time to live value (for multicast only)
-
-
-
‘connect=1|0’
-
Initialize the UDP socket with connect(). In this case, the
-destination address can’t be changed with ff_udp_set_remote_url later.
-If the destination address isn’t known at the start, this option can
-be specified in ff_udp_set_remote_url, too.
-This allows finding out the source address for the packets with getsockname,
-and makes writes return with AVERROR(ECONNREFUSED) if "destination
-unreachable" is received.
-For receiving, this gives the benefit of only receiving packets from
-the specified peer address/port.
-
-
-
-
Some usage examples of the udp protocol with ffmpeg follow.
-
-
To stream over UDP to a remote endpoint:
-
ffmpeg -i input -f format udp://hostname:port
-
-
-
To stream in mpegts format over UDP using 188 sized UDP packets, using a large input buffer:
-
A filtergraph is a directed graph of connected filters. It can contain
-cycles, and there can be multiple links between a pair of
-filters. Each link has one input pad on one side connecting it to one
-filter from which it takes its input, and one output pad on the other
-side connecting it to the one filter accepting its output.
-
-
Each filter in a filtergraph is an instance of a filter class
-registered in the application, which defines the features and the
-number of input and output pads of the filter.
-
-
A filter with no input pads is called a "source", a filter with no
-output pads is called a "sink".
-
A filtergraph can be represented using a textual representation, which
-is recognized by the -vf option of the ff*
-tools, and by the avfilter_graph_parse() function defined in
-‘libavfilter/avfiltergraph.h’.
-
-
A filterchain consists of a sequence of connected filters, each one
-connected to the previous one in the sequence. A filterchain is
-represented by a list of ","-separated filter descriptions.
-
-
A filtergraph consists of a sequence of filterchains. A sequence of
-filterchains is represented by a list of ";"-separated filterchain
-descriptions.
-
-
A filter is represented by a string of the form:
-[in_link_1]...[in_link_N]filter_name=arguments[out_link_1]...[out_link_M]
-
-
filter_name is the name of the filter class of which the
-described filter is an instance of, and has to be the name of one of
-the filter classes registered in the program.
-The name of the filter class is optionally followed by a string
-"=arguments".
-
-
arguments is a string which contains the parameters used to
-initialize the filter instance, and are described in the filter
-descriptions below.
-
-
The list of arguments can be quoted using the character "’" as initial
-and ending mark, and the character ’\’ for escaping the characters
-within the quoted text; otherwise the argument string is considered
-terminated when the next special character (belonging to the set
-"[]=;,") is encountered.
-
-
The name and arguments of the filter are optionally preceded and
-followed by a list of link labels.
-A link label allows to name a link and associate it to a filter output
-or input pad. The preceding labels in_link_1
-... in_link_N, are associated to the filter input pads,
-the following labels out_link_1 ... out_link_M, are
-associated to the output pads.
-
-
When two link labels with the same name are found in the
-filtergraph, a link between the corresponding input and output pad is
-created.
-
-
If an output pad is not labelled, it is linked by default to the first
-unlabelled input pad of the next filter in the filterchain.
-For example in the filterchain:
-
nullsrc, split[L1], [L2]overlay, nullsink
-
-
the split filter instance has two output pads, and the overlay filter
-instance two input pads. The first output pad of split is labelled
-"L1", the first input pad of overlay is labelled "L2", and the second
-output pad of split is linked to the second input pad of overlay,
-which are both unlabelled.
-
-
In a complete filterchain all the unlabelled filter input and output
-pads must be connected. A filtergraph is considered valid if all the
-filter input and output pads of all the filterchains are connected.
-
-
Follows a BNF description for the filtergraph syntax:
-
NAME ::= sequence of alphanumeric characters and '_'
-LINKLABEL ::= "[" NAME "]"
-LINKLABELS ::= LINKLABEL [LINKLABELS]
-FILTER_ARGUMENTS ::= sequence of chars (eventually quoted)
-FILTER ::= [LINKNAMES] NAME ["=" ARGUMENTS] [LINKNAMES]
-FILTERCHAIN ::= FILTER [,FILTERCHAIN]
-FILTERGRAPH ::= FILTERCHAIN [;FILTERGRAPH]
-
When you configure your FFmpeg build, you can disable any of the
-existing filters using --disable-filters.
-The configure output will show the audio filters included in your
-build.
-
-
Below is a description of the currently available audio filters.
-
Merge two audio streams into a single multi-channel stream.
-
-
This filter does not need any argument.
-
-
If the channel layouts of the inputs are disjoint, and therefore compatible,
-the channel layout of the output will be set accordingly and the channels
-will be reordered as necessary. If the channel layouts of the inputs are not
-disjoint, the output will have all the channels of the first input then all
-the channels of the second input, in that order, and the channel layout of
-the output will be the default value corresponding to the total number of
-channels.
-
-
For example, if the first input is in 2.1 (FL+FR+LF) and the second input
-is FC+BL+BR, then the output will be in 5.1, with the channels in the
-following order: a1, a2, b1, a3, b2, b3 (a1 is the first channel of the
-first input, b1 is the first channel of the second input).
-
-
On the other hand, if both input are in stereo, the output channels will be
-in the default order: a1, a2, b1, b2, and the channel layout will be
-arbitrarily set to 4.0, which may or may not be the expected value.
-
-
Both inputs must have the same sample rate, format and packing.
-
-
If inputs do not have the same duration, the output will stop with the
-shortest.
-
-
Example: merge two mono files into a stereo stream:
-
Resample the input audio to the specified sample rate.
-
-
The filter accepts exactly one parameter, the output sample rate. If not
-specified then the filter will automatically convert between its input
-and output sample rates.
-
-
For example, to resample the input audio to 44100Hz:
-
Show a line containing various information for each input audio frame.
-The input audio is not modified.
-
-
The shown line contains a sequence of key/value pairs of the form
-key:value.
-
-
A description of each shown parameter follows:
-
-
-
‘n’
-
sequential number of the input frame, starting from 0
-
-
-
‘pts’
-
presentation TimeStamp of the input frame, expressed as a number of
-time base units. The time base unit depends on the filter input pad, and
-is usually 1/sample_rate.
-
-
-
‘pts_time’
-
presentation TimeStamp of the input frame, expressed as a number of
-seconds
-
-
-
‘pos’
-
position of the frame in the input stream, -1 if this information in
-unavailable and/or meaningless (for example in case of synthetic audio)
-
-
-
‘fmt’
-
sample format name
-
-
-
‘chlayout’
-
channel layout description
-
-
-
‘nb_samples’
-
number of samples (per each channel) contained in the filtered frame
-
-
-
‘rate’
-
sample rate for the audio frame
-
-
-
‘planar’
-
if the packing format is planar, 0 if packed
-
-
-
‘checksum’
-
Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame
-
-
-
‘plane_checksum’
-
Adler-32 checksum (printed in hexadecimal) for each input frame plane,
-expressed in the form "[c0c1c2c3c4c5
-c6c7]"
-
Forward two audio streams and control the order the buffers are forwarded.
-
-
The argument to the filter is an expression deciding which stream should be
-forwarded next: if the result is negative, the first stream is forwarded; if
-the result is positive or zero, the second stream is forwarded. It can use
-the following variables:
-
-
-
b1 b2
-
number of buffers forwarded so far on each stream
-
-
s1 s2
-
number of samples forwarded so far on each stream
-
-
t1 t2
-
current timestamp of each stream
-
-
-
-
The default value is t1-t2, which means to always forward the stream
-that has a smaller timestamp.
-
-
Example: stress-test amerge by randomly sending buffers on the wrong
-input, while avoiding too much of a desynchronization:
-
This filter adds ‘cues’ to 44.1kHz stereo (i.e. audio CD format) audio
-so that when listened to on headphones the stereo image is moved from
-inside your head (standard for headphones) to outside and in front of
-the listener (standard for speakers).
-
Mix channels with specific gain levels. The filter accepts the output
-channel layout followed by a set of channels definitions.
-
-
This filter is also designed to remap efficiently the channels of an audio
-stream.
-
-
The filter accepts parameters of the form:
-"l:outdef:outdef:..."
-
-
-
‘l’
-
output channel layout or number of channels
-
-
-
‘outdef’
-
output channel specification, of the form:
-"out_name=[gain*]in_name[+[gain*]in_name...]"
-
-
-
‘out_name’
-
output channel to define, either a channel name (FL, FR, etc.) or a channel
-number (c0, c1, etc.)
-
-
-
‘gain’
-
multiplicative coefficient for the channel, 1 leaving the volume unchanged
-
-
-
‘in_name’
-
input channel to use, see out_name for details; it is not possible to mix
-named and numbered input channels
-
-
-
-
If the ‘=’ in a channel specification is replaced by ‘<’, then the gains for
-that specification will be renormalized so that the total is 1, thus
-avoiding clipping noise.
-
Note that ffmpeg integrates a default down-mix (and up-mix) system
-that should be preferred (see "-ac" option) unless you have very specific
-needs.
-
The channel remapping will be effective if, and only if:
-
-
-
gain coefficients are zeroes or ones,
-
only one input per channel output,
-
the number of output channels is supported by libswresample (16 at the
- moment)
-
-
-
If all these conditions are satisfied, the filter will notify the user ("Pure
-channel mapping detected"), and use an optimized and lossless method to do the
-remapping.
-
-
For example, if you have a 5.1 source and want a stereo audio stream by
-dropping the extra channels:
-
pan="stereo: c0=FL : c1=FR"
-
-
-
Given the same source, you can also switch front left and front right channels
-and keep the input channel layout:
-
This filter logs a message when it detects that the input audio volume is less
-or equal to a noise tolerance value for a duration greater or equal to the
-minimum detected noise duration.
-
-
The printed times and duration are expressed in seconds.
-
-
-
‘duration, d’
-
Set silence duration until notification (default is 2 seconds).
-
-
-
‘noise, n’
-
Set noise tolerance. Can be specified in dB (in case "dB" is appended to the
-specified value) or amplitude ratio. Default is -60dB, or 0.001.
-
-
-
-
Detect 5 seconds of silence with -50dB noise tolerance:
-
silencedetect=n=-50dB:d=5
-
-
-
Complete example with ffmpeg to detect silence with 0.0001 noise
-tolerance in ‘silence.mp3’:
-
The filter accepts exactly one parameter vol, which expresses
-how the audio volume will be increased or decreased.
-
-
Output values are clipped to the maximum value.
-
-
If vol is expressed as a decimal number, the output audio
-volume is given by the relation:
-
output_volume = vol * input_volume
-
-
-
If vol is expressed as a decimal number followed by the string
-"dB", the value represents the requested change in decibels of the
-input audio power, and the output audio volume is given by the
-relation:
-
output_volume = 10^(vol/20) * input_volume
-
-
-
Otherwise vol is considered an expression and its evaluated
-value is used for computing the output audio volume according to the
-first relation.
-
Buffer audio frames, and make them available to the filter chain.
-
-
This source is mainly intended for a programmatic use, in particular
-through the interface defined in ‘libavfilter/asrc_abuffer.h’.
-
-
It accepts the following mandatory parameters:
-sample_rate:sample_fmt:channel_layout:packing
-
-
-
‘sample_rate’
-
The sample rate of the incoming audio buffers.
-
-
-
‘sample_fmt’
-
The sample format of the incoming audio buffers.
-Either a sample format name or its corresponging integer representation from
-the enum AVSampleFormat in ‘libavutil/samplefmt.h’
-
-
-
‘channel_layout’
-
The channel layout of the incoming audio buffers.
-Either a channel layout name from channel_layout_map in
-‘libavutil/audioconvert.c’ or its corresponding integer representation
-from the AV_CH_LAYOUT_* macros in ‘libavutil/audioconvert.h’
-
-
-
‘packing’
-
Either "packed" or "planar", or their integer representation: 0 or 1
-respectively.
-
-
-
-
-
For example:
-
abuffer=44100:s16:stereo:planar
-
-
-
will instruct the source to accept planar 16bit signed stereo at 44100Hz.
-Since the sample format with name "s16" corresponds to the number
-1 and the "stereo" channel layout corresponds to the value 3, this is
-equivalent to:
-
Generate an audio signal specified by an expression.
-
-
This source accepts in input one or more expressions (one for each
-channel), which are evaluated and used to generate a corresponding
-audio signal.
-
-
It accepts the syntax: exprs[::options].
-exprs is a list of expressions separated by ":", one for each
-separate channel. The output channel layout depends on the number of
-provided expressions, up to 8 channels are supported.
-
-
options is an optional sequence of key=value pairs,
-separated by ":".
-
-
The description of the accepted options follows.
-
-
-
‘duration, d’
-
Set the minimum duration of the sourced audio. See the function
-av_parse_time() for the accepted format.
-Note that the resulting duration may be greater than the specified
-duration, as the generated audio is always cut at the end of a
-complete frame.
-
-
If not specified, or the expressed duration is negative, the audio is
-supposed to be generated forever.
-
-
-
‘nb_samples, n’
-
Set the number of samples per channel per each output frame,
-default to 1024.
-
-
-
‘sample_rate, s’
-
Specify the sample rate, default to 44100.
-
-
-
-
Each expression in exprs can contain the following constants:
-
-
-
‘n’
-
number of the evaluated sample, starting from 0
-
-
-
‘t’
-
time of the evaluated sample expressed in seconds, starting from 0
-
It accepts the syntax: movie_name[:options] where
-movie_name is the name of the resource to read (not necessarily
-a file but also a device or a stream accessed through some protocol),
-and options is an optional sequence of key=value
-pairs, separated by ":".
-
-
The description of the accepted options follows.
-
-
-
‘format_name, f’
-
Specify the format assumed for the movie to read, and can be either
-the name of a container or an input device. If not specified the
-format is guessed from movie_name or by probing.
-
-
-
‘seek_point, sp’
-
Specify the seek point in seconds, the frames will be output
-starting from this seek point, the parameter is evaluated with
-av_strtod so the numerical value may be suffixed by an IS
-postfix. Default value is "0".
-
-
-
‘stream_index, si’
-
Specify the index of the audio stream to read. If the value is -1,
-the best suited audio stream will be automatically selected. Default
-value is "-1".
-
Null audio source, return unprocessed audio frames. It is mainly useful
-as a template and to be employed in analysis / debugging tools, or as
-the source for filters which ignore the input data (for example the sox
-synth filter).
-
-
It accepts an optional sequence of key=value pairs,
-separated by ":".
-
-
The description of the accepted options follows.
-
-
-
‘sample_rate, s’
-
Specify the sample rate, and defaults to 44100.
-
-
-
‘channel_layout, cl’
-
-
Specify the channel layout, and can be either an integer or a string
-representing a channel layout. The default value of channel_layout
-is "stereo".
-
-
Check the channel_layout_map definition in
-‘libavcodec/audioconvert.c’ for the mapping between strings and
-channel layout values.
-
-
-
‘nb_samples, n’
-
Set the number of samples per requested frames.
-
-
-
-
-
Follow some examples:
-
# set the sample rate to 48000 Hz and the channel layout to AV_CH_LAYOUT_MONO.
-anullsrc=r=48000:cl=4
-
-# same as
-anullsrc=r=48000:cl=mono
-
Buffer audio frames, and make them available to the end of filter chain.
-
-
This sink is mainly intended for programmatic use, in particular
-through the interface defined in ‘libavfilter/buffersink.h’.
-
-
It requires a pointer to an AVABufferSinkContext structure, which
-defines the incoming buffers’ formats, to be passed as the opaque
-parameter to avfilter_init_filter for initialization.
-
When you configure your FFmpeg build, you can disable any of the
-existing filters using --disable-filters.
-The configure output will show the video filters included in your
-build.
-
-
Below is a description of the currently available video filters.
-
Detect frames that are (almost) completely black. Can be useful to
-detect chapter transitions or commercials. Output lines consist of
-the frame number of the detected frame, the percentage of blackness,
-the position in the file if known or -1 and the timestamp in seconds.
-
-
In order to display the output lines, you need to set the loglevel at
-least to the AV_LOG_INFO value.
-
-
The filter accepts the syntax:
-
blackframe[=amount:[threshold]]
-
-
-
amount is the percentage of the pixels that have to be below the
-threshold, and defaults to 98.
-
-
threshold is the threshold below which a pixel value is
-considered black, and defaults to 32.
-
This filter accepts the parameters:
-luma_radius:luma_power:chroma_radius:chroma_power:alpha_radius:alpha_power
-
-
Chroma and alpha parameters are optional, if not specified they default
-to the corresponding values set for luma_radius and
-luma_power.
-
-
luma_radius, chroma_radius, and alpha_radius represent
-the radius in pixels of the box used for blurring the corresponding
-input plane. They are expressions, and can contain the following
-constants:
-
-
‘w, h’
-
the input width and height in pixels
-
-
-
‘cw, ch’
-
the input chroma image width and height in pixels
-
-
-
‘hsub, vsub’
-
horizontal and vertical chroma subsample values. For example for the
-pixel format "yuv422p" hsub is 2 and vsub is 1.
-
-
-
-
The radius must be a non-negative number, and must not be greater than
-the value of the expression min(w,h)/2 for the luma and alpha planes,
-and of min(cw,ch)/2 for the chroma planes.
-
-
luma_power, chroma_power, and alpha_power represent
-how many times the boxblur filter is applied to the corresponding
-plane.
-
-
Some examples follow:
-
-
-
-Apply a boxblur filter with luma, chroma, and alpha radius
-set to 2:
-
boxblur=2:1
-
-
-
-Set luma radius to 2, alpha and chroma radius to 0
-
boxblur=2:1:0:0:0:0
-
-
-
-Set luma and chroma radius to a fraction of the video dimension
-
The parameters are expressions containing the following constants:
-
-
-
‘x, y’
-
the computed values for x and y. They are evaluated for
-each new frame.
-
-
-
‘in_w, in_h’
-
the input width and height
-
-
-
‘iw, ih’
-
same as in_w and in_h
-
-
-
‘out_w, out_h’
-
the output (cropped) width and height
-
-
-
‘ow, oh’
-
same as out_w and out_h
-
-
-
‘a’
-
same as iw / ih
-
-
-
‘sar’
-
input sample aspect ratio
-
-
-
‘dar’
-
input display aspect ratio, it is the same as (iw / ih) * sar
-
-
-
‘hsub, vsub’
-
horizontal and vertical chroma subsample values. For example for the
-pixel format "yuv422p" hsub is 2 and vsub is 1.
-
-
-
‘n’
-
the number of input frame, starting from 0
-
-
-
‘pos’
-
the position in the file of the input frame, NAN if unknown
-
-
-
‘t’
-
timestamp expressed in seconds, NAN if the input timestamp is unknown
-
-
-
-
-
The out_w and out_h parameters specify the expressions for
-the width and height of the output (cropped) video. They are
-evaluated just at the configuration of the filter.
-
-
The default value of out_w is "in_w", and the default value of
-out_h is "in_h".
-
-
The expression for out_w may depend on the value of out_h,
-and the expression for out_h may depend on out_w, but they
-cannot depend on x and y, as x and y are
-evaluated after out_w and out_h.
-
-
The x and y parameters specify the expressions for the
-position of the top-left corner of the output (non-cropped) area. They
-are evaluated for each frame. If the evaluated value is not valid, it
-is approximated to the nearest valid value.
-
-
The default value of x is "(in_w-out_w)/2", and the default
-value for y is "(in_h-out_h)/2", which set the cropped area at
-the center of the input image.
-
-
The expression for x may depend on y, and the expression
-for y may depend on x.
-
-
Follow some examples:
-
# crop the central input area with size 100x100
-crop=100:100
-
-# crop the central input area with size 2/3 of the input video
-"crop=2/3*in_w:2/3*in_h"
-
-# crop the input video central square
-crop=in_h
-
-# delimit the rectangle with the top-left corner placed at position
-# 100:100 and the right-bottom corner corresponding to the right-bottom
-# corner of the input image.
-crop=in_w-100:in_h-100:100:100
-
-# crop 10 pixels from the left and right borders, and 20 pixels from
-# the top and bottom borders
-"crop=in_w-2*10:in_h-2*20"
-
-# keep only the bottom right quarter of the input image
-"crop=in_w/2:in_h/2:in_w/2:in_h/2"
-
-# crop height for getting Greek harmony
-"crop=in_w:1/PHI*in_w"
-
-# trembling effect
-"crop=in_w/2:in_h/2:(in_w-out_w)/2+((in_w-out_w)/2)*sin(n/10):(in_h-out_h)/2 +((in_h-out_h)/2)*sin(n/7)"
-
-# erratic camera effect depending on timestamp
-"crop=in_w/2:in_h/2:(in_w-out_w)/2+((in_w-out_w)/2)*sin(t*10):(in_h-out_h)/2 +((in_h-out_h)/2)*sin(t*13)"
-
-# set x depending on the value of y
-"crop=in_w/2:in_h/2:y:10+10*sin(n/10)"
-
Calculate necessary cropping parameters and prints the recommended
-parameters through the logging system. The detected dimensions
-correspond to the non-black area of the input video.
-
-
It accepts the syntax:
-
cropdetect[=limit[:round[:reset]]]
-
-
-
-
‘limit’
-
Threshold, which can be optionally specified from nothing (0) to
-everything (255), defaults to 24.
-
-
-
‘round’
-
Value which the width/height should be divisible by, defaults to
-16. The offset is automatically adjusted to center the video. Use 2 to
-get only even dimensions (needed for 4:2:2 video). 16 is best when
-encoding to most video codecs.
-
-
-
‘reset’
-
Counter that determines after how many frames cropdetect will reset
-the previously detected largest video area and start over to detect
-the current optimal crop area. Defaults to 0.
-
-
This can be useful when channel logos distort the video area. 0
-indicates never reset and return the largest area encountered during
-playback.
-
Suppress a TV station logo by a simple interpolation of the surrounding
-pixels. Just set a rectangle covering the logo and watch it disappear
-(and sometimes something even uglier appear - your mileage may vary).
-
-
The filter accepts parameters as a string of the form
-"x:y:w:h:band", or as a list of
-key=value pairs, separated by ":".
-
-
The description of the accepted parameters follows.
-
-
-
‘x, y’
-
Specify the top left corner coordinates of the logo. They must be
-specified.
-
-
-
‘w, h’
-
Specify the width and height of the logo to clear. They must be
-specified.
-
-
-
‘band, t’
-
Specify the thickness of the fuzzy edge of the rectangle (added to
-w and h). The default value is 4.
-
-
-
‘show’
-
When set to 1, a green rectangle is drawn on the screen to simplify
-finding the right x, y, w, h parameters, and
-band is set to 4. The default value is 0.
-
-
-
-
-
Some examples follow.
-
-
-
-Set a rectangle covering the area with top left corner coordinates 0,0
-and size 100x77, setting a band of size 10:
-
delogo=0:0:100:77:10
-
-
-
-As the previous example, but use named options:
-
Attempt to fix small changes in horizontal and/or vertical shift. This
-filter helps remove camera shake from hand-holding a camera, bumping a
-tripod, moving on a vehicle, etc.
-
-
The filter accepts parameters as a string of the form
-"x:y:w:h:rx:ry:edge:blocksize:contrast:search:filename"
-
-
A description of the accepted parameters follows.
-
-
-
‘x, y, w, h’
-
Specify a rectangular area where to limit the search for motion
-vectors.
-If desired the search for motion vectors can be limited to a
-rectangular area of the frame defined by its top left corner, width
-and height. These parameters have the same meaning as the drawbox
-filter which can be used to visualise the position of the bounding
-box.
-
-
This is useful when simultaneous movement of subjects within the frame
-might be confused for camera motion by the motion vector search.
-
-
If any or all of x, y, w and h are set to -1
-then the full frame is used. This allows later options to be set
-without specifying the bounding box for the motion vector search.
-
-
Default - search the whole frame.
-
-
-
‘rx, ry’
-
Specify the maximum extent of movement in x and y directions in the
-range 0-64 pixels. Default 16.
-
-
-
‘edge’
-
Specify how to generate pixels to fill blanks at the edge of the
-frame. An integer from 0 to 3 as follows:
-
-
‘0’
-
Fill zeroes at blank locations
-
-
‘1’
-
Original image at blank locations
-
-
‘2’
-
Extruded edge value at blank locations
-
-
‘3’
-
Mirrored edge at blank locations
-
-
-
-
The default setting is mirror edge at blank locations.
-
-
-
‘blocksize’
-
Specify the blocksize to use for motion search. Range 4-128 pixels,
-default 8.
-
-
-
‘contrast’
-
Specify the contrast threshold for blocks. Only blocks with more than
-the specified contrast (difference between darkest and lightest
-pixels) will be considered. Range 1-255, default 125.
-
-
-
‘search’
-
Specify the search strategy 0 = exhaustive search, 1 = less exhaustive
-search. Default - exhaustive search.
-
-
-
‘filename’
-
If set then a detailed log of the motion search is written to the
-specified file.
-
Draw text string or text from specified file on top of video using the
-libfreetype library.
-
-
To enable compilation of this filter you need to configure FFmpeg with
---enable-libfreetype.
-
-
The filter also recognizes strftime() sequences in the provided text
-and expands them accordingly. Check the documentation of strftime().
-
-
The filter accepts parameters as a list of key=value pairs,
-separated by ":".
-
-
The description of the accepted parameters follows.
-
-
-
‘fontfile’
-
The font file to be used for drawing text. Path must be included.
-This parameter is mandatory.
-
-
-
‘text’
-
The text string to be drawn. The text must be a sequence of UTF-8
-encoded characters.
-This parameter is mandatory if no file is specified with the parameter
-textfile.
-
-
-
‘textfile’
-
A text file containing text to be drawn. The text must be a sequence
-of UTF-8 encoded characters.
-
-
This parameter is mandatory if no text string is specified with the
-parameter text.
-
-
If both text and textfile are specified, an error is thrown.
-
-
-
‘x, y’
-
The expressions which specify the offsets where text will be drawn
-within the video frame. They are relative to the top/left border of the
-output image.
-
-
The default value of x and y is "0".
-
-
See below for the list of accepted constants.
-
-
-
‘fontsize’
-
The font size to be used for drawing text.
-The default value of fontsize is 16.
-
-
-
‘fontcolor’
-
The color to be used for drawing fonts.
-Either a string (e.g. "red") or in 0xRRGGBB[AA] format
-(e.g. "0xff000033"), possibly followed by an alpha specifier.
-The default value of fontcolor is "black".
-
-
-
‘boxcolor’
-
The color to be used for drawing box around text.
-Either a string (e.g. "yellow") or in 0xRRGGBB[AA] format
-(e.g. "0xff00ff"), possibly followed by an alpha specifier.
-The default value of boxcolor is "white".
-
-
-
‘box’
-
Used to draw a box around text using background color.
-Value should be either 1 (enable) or 0 (disable).
-The default value of box is 0.
-
-
-
‘shadowx, shadowy’
-
The x and y offsets for the text shadow position with respect to the
-position of the text. They can be either positive or negative
-values. Default value for both is "0".
-
-
-
‘shadowcolor’
-
The color to be used for drawing a shadow behind the drawn text. It
-can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA]
-form (e.g. "0xff00ff"), possibly followed by an alpha specifier.
-The default value of shadowcolor is "black".
-
-
-
‘ft_load_flags’
-
Flags to be used for loading the fonts.
-
-
The flags map the corresponding flags supported by libfreetype, and are
-a combination of the following values:
-
-
default
-
no_scale
-
no_hinting
-
render
-
no_bitmap
-
vertical_layout
-
force_autohint
-
crop_bitmap
-
pedantic
-
ignore_global_advance_width
-
no_recurse
-
ignore_transform
-
monochrome
-
linear_design
-
no_autohint
-
end table
-
-
-
Default value is "render".
-
-
For more information consult the documentation for the FT_LOAD_*
-libfreetype flags.
-
-
-
‘tabsize’
-
The size in number of spaces to use for rendering the tab.
-Default value is 4.
-
-
-
-
The parameters for x and y are expressions containing the
-following constants:
-
-
-
‘W, H’
-
the input width and height
-
-
-
‘tw, text_w’
-
the width of the rendered text
-
-
-
‘th, text_h’
-
the height of the rendered text
-
-
-
‘lh, line_h’
-
the height of each text line
-
-
-
‘sar’
-
input sample aspect ratio
-
-
-
‘dar’
-
input display aspect ratio, it is the same as (w / h) * sar
-
-
-
‘hsub, vsub’
-
horizontal and vertical chroma subsample values. For example for the
-pixel format "yuv422p" hsub is 2 and vsub is 1.
-
-
-
‘max_glyph_w’
-
maximum glyph width, that is the maximum width for all the glyphs
-contained in the rendered text
-
-
-
‘max_glyph_h’
-
maximum glyph height, that is the maximum height for all the glyphs
-contained in the rendered text, it is equivalent to ascent -
-descent.
-
-
-
‘max_glyph_a, ascent’
-
-
the maximum distance from the baseline to the highest/upper grid
-coordinate used to place a glyph outline point, for all the rendered
-glyphs.
-It is a positive value, due to the grid’s orientation with the Y axis
-upwards.
-
-
-
‘max_glyph_d, descent’
-
the maximum distance from the baseline to the lowest grid coordinate
-used to place a glyph outline point, for all the rendered glyphs.
-This is a negative value, due to the grid’s orientation, with the Y axis
-upwards.
-
-
-
‘n’
-
the number of input frame, starting from 0
-
-
-
‘t’
-
timestamp expressed in seconds, NAN if the input timestamp is unknown
-
-
-
‘timecode’
-
initial timecode representation in "hh:mm:ss[:;.]ff" format. It can be used
-with or without text parameter. rate option must be specified.
-Note that timecode options are not effective if FFmpeg is build with
---disable-avcodec.
-
-
-
‘r, rate’
-
frame rate (timecode only)
-
-
-
-
Some examples follow.
-
-
-
-Draw "Test Text" with font FreeSerif, using the default values for the
-optional parameters.
-
-
-Draw ’Test Text’ with font FreeSerif of size 24 at position x=100
-and y=50 (counting from the top-left corner of the screen), text is
-yellow with a red box around it. Both the text and the box have an
-opacity of 20%.
-
-
-Show a text line sliding from right to left in the last row of the video
-frame. The file ‘LONG_LINE’ is assumed to contain a single line
-with no newlines.
-
It accepts the parameters:
-type:start_frame:nb_frames[:options]
-
-
type specifies if the effect type, can be either "in" for
-fade-in, or "out" for a fade-out effect.
-
-
start_frame specifies the number of the start frame for starting
-to apply the fade effect.
-
-
nb_frames specifies the number of frames for which the fade
-effect has to last. At the end of the fade-in effect the output video
-will have the same intensity as the input video, at the end of the
-fade-out transition the output video will be completely black.
-
-
options is an optional sequence of key=value pairs,
-separated by ":". The description of the accepted options follows.
-
-
-
‘type, t’
-
See type.
-
-
-
‘start_frame, s’
-
See start_frame.
-
-
-
‘nb_frames, n’
-
See nb_frames.
-
-
-
‘alpha’
-
If set to 1, fade only alpha channel, if one exists on the input.
-Default value is 0.
-
-
-
-
A few usage examples follow, usable too as test scenarios.
-
# fade in first 30 frames of video
-fade=in:0:30
-
-# fade out last 45 frames of a 200-frame video
-fade=out:155:45
-
-# fade in first 25 frames and fade out last 25 frames of a 1000-frame video
-fade=in:0:25, fade=out:975:25
-
-# make first 5 frames black, then fade in from frame 5-24
-fade=in:5:20
-
-# fade in alpha over first 25 frames of video
-fade=in:0:25:alpha=1
-
It accepts one parameter which specifies the required field order that
-the input interlaced video will be transformed to. The parameter can
-assume one of the following values:
-
-
-
‘0 or bff’
-
output bottom field first
-
-
‘1 or tff’
-
output top field first
-
-
-
-
Default value is "tff".
-
-
Transformation is achieved by shifting the picture content up or down
-by one line, and filling the remaining line with appropriate picture content.
-This method is consistent with most broadcast field order converters.
-
-
If the input video is not flagged as being interlaced, or it is already
-flagged as being of the required output field order then this filter does
-not alter the incoming video.
-
-
This filter is very useful when converting to or from PAL DV material,
-which is bottom field first.
-
Convert the input video to one of the specified pixel formats.
-Libavfilter will try to pick one that is supported for the input to
-the next filter.
-
-
The filter accepts a list of pixel format names, separated by ":",
-for example "yuv420p:monow:rgb24".
-
-
Some examples follow:
-
# convert the input video to the format "yuv420p"
-format=yuv420p
-
-# convert the input video to any of the formats in the list
-format=yuv420p:yuv444p:yuv410p
-
To enable compilation of this filter you need to install the frei0r
-header and configure FFmpeg with --enable-frei0r.
-
-
The filter supports the syntax:
-
filter_name[{:|=}param1:param2:...:paramN]
-
-
-
filter_name is the name to the frei0r effect to load. If the
-environment variable FREI0R_PATH is defined, the frei0r effect
-is searched in each one of the directories specified by the colon
-separated list in FREIOR_PATH, otherwise in the standard frei0r
-paths, which are in this order: ‘HOME/.frei0r-1/lib/’,
-‘/usr/local/lib/frei0r-1/’, ‘/usr/lib/frei0r-1/’.
-
-
param1, param2, ... , paramN specify the parameters
-for the frei0r effect.
-
-
A frei0r effect parameter can be a boolean (whose values are specified
-with "y" and "n"), a double, a color (specified by the syntax
-R/G/B, R, G, and B being float
-numbers from 0.0 to 1.0) or by an av_parse_color() color
-description), a position (specified by the syntax X/Y,
-X and Y being float numbers) and a string.
-
-
The number and kind of parameters depend on the loaded effect. If an
-effect parameter is not specified the default value is set.
-
-
Some examples follow:
-
# apply the distort0r effect, set the first two double parameters
-frei0r=distort0r:0.5:0.01
-
-# apply the colordistance effect, takes a color as first parameter
-frei0r=colordistance:0.2/0.3/0.4
-frei0r=colordistance:violet
-frei0r=colordistance:0x112233
-
-# apply the perspective effect, specify the top left and top right
-# image positions
-frei0r=perspective:0.2/0.2:0.8/0.2
-
Fix the banding artifacts that are sometimes introduced into nearly flat
-regions by truncation to 8bit color depth.
-Interpolate the gradients that should go where the bands are, and
-dither them.
-
-
This filter is designed for playback only. Do not use it prior to
-lossy compression, because compression tends to lose the dither and
-bring back the bands.
-
-
The filter takes two optional parameters, separated by ’:’:
-strength:radius
-
-
strength is the maximum amount by which the filter will change
-any one pixel. Also the threshold for detecting nearly flat
-regions. Acceptable values range from .51 to 255, default value is
-1.2, out-of-range values will be clipped to the valid range.
-
-
radius is the neighborhood to fit the gradient to. A larger
-radius makes for smoother gradients, but also prevents the filter from
-modifying the pixels near detailed regions. Acceptable values are
-8-32, default value is 16, out-of-range values will be clipped to the
-valid range.
-
High precision/quality 3d denoise filter. This filter aims to reduce
-image noise producing smooth images and making still images really
-still. It should enhance compressibility.
-
-
It accepts the following optional parameters:
-luma_spatial:chroma_spatial:luma_tmp:chroma_tmp
-
-
-
‘luma_spatial’
-
a non-negative float number which specifies spatial luma strength,
-defaults to 4.0
-
-
-
‘chroma_spatial’
-
a non-negative float number which specifies spatial chroma strength,
-defaults to 3.0*luma_spatial/4.0
-
-
-
‘luma_tmp’
-
a float number which specifies luma temporal strength, defaults to
-6.0*luma_spatial/4.0
-
-
-
‘chroma_tmp’
-
a float number which specifies chroma temporal strength, defaults to
-luma_tmp*chroma_spatial/luma_spatial
-
Compute a look-up table for binding each pixel component input value
-to an output value, and apply it to input video.
-
-
lutyuv applies a lookup table to a YUV input video, lutrgb
-to an RGB input video.
-
-
These filters accept in input a ":"-separated list of options, which
-specify the expressions used for computing the lookup table for the
-corresponding pixel component values.
-
-
The lut filter requires either YUV or RGB pixel formats in
-input, and accepts the options:
-
-
‘c0’
-
first pixel component
-
-
‘c1’
-
second pixel component
-
-
‘c2’
-
third pixel component
-
-
‘c3’
-
fourth pixel component, corresponds to the alpha component
-
-
-
-
The exact component associated to each option depends on the format in
-input.
-
-
The lutrgb filter requires RGB pixel formats in input, and
-accepts the options:
-
-
‘r’
-
red component
-
-
‘g’
-
green component
-
-
‘b’
-
blue component
-
-
‘a’
-
alpha component
-
-
-
-
The lutyuv filter requires YUV pixel formats in input, and
-accepts the options:
-
-
‘y’
-
Y/luminance component
-
-
‘u’
-
U/Cb component
-
-
‘v’
-
V/Cr component
-
-
‘a’
-
alpha component
-
-
-
-
The expressions can contain the following constants and functions:
-
-
-
‘w, h’
-
the input width and height
-
-
-
‘val’
-
input value for the pixel component
-
-
-
‘clipval’
-
the input value clipped in the minval-maxval range
-
-
-
‘maxval’
-
maximum value for the pixel component
-
-
-
‘minval’
-
minimum value for the pixel component
-
-
-
‘negval’
-
the negated value for the pixel component value clipped in the
-minval-maxval range , it corresponds to the expression
-"maxval-clipval+minval"
-
-
-
‘clip(val)’
-
the computed value in val clipped in the
-minval-maxval range
-
-
-
‘gammaval(gamma)’
-
the computed gamma correction value of the pixel component value
-clipped in the minval-maxval range, corresponds to the
-expression
-"pow((clipval-minval)/(maxval-minval)\,gamma)*(maxval-minval)+minval"
-
-
-
-
-
All expressions default to "val".
-
-
Some examples follow:
-
# negate input video
-lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
-lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
-
-# the above is the same as
-lutrgb="r=negval:g=negval:b=negval"
-lutyuv="y=negval:u=negval:v=negval"
-
-# negate luminance
-lutyuv=y=negval
-
-# remove chroma components, turns the video into a graytone image
-lutyuv="u=128:v=128"
-
-# apply a luma burning effect
-lutyuv="y=2*val"
-
-# remove green and blue components
-lutrgb="g=0:b=0"
-
-# set a constant alpha channel value on input
-format=rgba,lutrgb=a="maxval-minval/2"
-
-# correct luminance gamma by a 0.5 factor
-lutyuv=y=gammaval(0.5)
-
This filter provides a wrapper around most of the filters of
-MPlayer/MEncoder.
-
-
This wrapper is considered experimental. Some of the wrapped filters
-may not work properly and we may drop support for them, as they will
-be implemented natively into FFmpeg. Thus you should avoid
-depending on them when writing portable scripts.
-
-
The filters accepts the parameters:
-filter_name[:=]filter_params
-
-
filter_name is the name of a supported MPlayer filter,
-filter_params is a string containing the parameters accepted by
-the named filter.
-
-
The list of the currently supported filters follows:
-
-
2xsai
-
decimate
-
denoise3d
-
detc
-
dint
-
divtc
-
down3dright
-
dsize
-
eq2
-
eq
-
field
-
fil
-
fixpts
-
framestep
-
fspp
-
geq
-
harddup
-
hqdn3d
-
hue
-
il
-
ilpack
-
ivtc
-
kerndeint
-
mcdeint
-
mirror
-
noise
-
ow
-
palette
-
perspective
-
phase
-
pp7
-
pullup
-
qp
-
rectangle
-
remove-logo
-
rotate
-
sab
-
screenshot
-
smartblur
-
softpulldown
-
softskip
-
spp
-
swapuv
-
telecine
-
tile
-
tinterlace
-
unsharp
-
uspp
-
yuvcsp
-
yvu9
-
-
-
The parameter syntax and behavior for the listed filters are the same
-of the corresponding MPlayer filters. For detailed instructions check
-the "VIDEO FILTERS" section in the MPlayer manual.
-
-
Some examples follow:
-
# remove a logo by interpolating the surrounding pixels
-mp=delogo=200:200:80:20:1
-
-# adjust gamma, brightness, contrast
-mp=eq2=1.0:2:0.5
-
-# tweak hue and saturation
-mp=hue=100:-10
-
Force libavfilter not to use any of the specified pixel formats for the
-input to the next filter.
-
-
The filter accepts a list of pixel format names, separated by ":",
-for example "yuv420p:monow:rgb24".
-
-
Some examples follow:
-
# force libavfilter to use a format different from "yuv420p" for the
-# input to the vflip filter
-noformat=yuv420p,vflip
-
-# convert the input video to any of the formats not contained in the list
-noformat=yuv420p:yuv444p:yuv410p
-
Dilate an image by using a specific structuring element.
-This filter corresponds to the libopencv function cvDilate.
-
-
It accepts the parameters: struct_el:nb_iterations.
-
-
struct_el represents a structuring element, and has the syntax:
-colsxrows+anchor_xxanchor_y/shape
-
-
cols and rows represent the number of columns and rows of
-the structuring element, anchor_x and anchor_y the anchor
-point, and shape the shape for the structuring element, and
-can be one of the values "rect", "cross", "ellipse", "custom".
-
-
If the value for shape is "custom", it must be followed by a
-string of the form "=filename". The file with name
-filename is assumed to represent a binary image, with each
-printable character corresponding to a bright pixel. When a custom
-shape is used, cols and rows are ignored, the number
-or columns and rows of the read file are assumed instead.
-
-
The default value for struct_el is "3x3+0x0/rect".
-
-
nb_iterations specifies the number of times the transform is
-applied to the image, and defaults to 1.
-
-
Follow some example:
-
# use the default values
-ocv=dilate
-
-# dilate using a structuring element with a 5x5 cross, iterate two times
-ocv=dilate=5x5+2x2/cross:2
-
-# read the shape from the file diamond.shape, iterate two times
-# the file diamond.shape may contain a pattern of characters like this:
-# *
-# ***
-# *****
-# ***
-# *
-# the specified cols and rows are ignored (but not the anchor point coordinates)
-ocv=0x0+2x2/custom=diamond.shape:2
-
The filter takes the following parameters:
-type:param1:param2:param3:param4.
-
-
type is the type of smooth filter to apply, and can be one of
-the following values: "blur", "blur_no_scale", "median", "gaussian",
-"bilateral". The default value is "gaussian".
-
-
param1, param2, param3, and param4 are
-parameters whose meanings depend on smooth type. param1 and
-param2 accept integer positive values or 0, param3 and
-param4 accept float values.
-
-
The default value for param1 is 3, the default value for the
-other parameters is 0.
-
-
These parameters correspond to the parameters assigned to the
-libopencv function cvSmooth.
-
It takes two inputs and one output, the first input is the "main"
-video on which the second input is overlayed.
-
-
It accepts the parameters: x:y[:options].
-
-
x is the x coordinate of the overlayed video on the main video,
-y is the y coordinate. x and y are expressions containing
-the following parameters:
-
-
-
‘main_w, main_h’
-
main input width and height
-
-
-
‘W, H’
-
same as main_w and main_h
-
-
-
‘overlay_w, overlay_h’
-
overlay input width and height
-
-
-
‘w, h’
-
same as overlay_w and overlay_h
-
-
-
-
options is an optional list of key=value pairs,
-separated by ":".
-
-
The description of the accepted options follows.
-
-
-
‘rgb’
-
If set to 1, force the filter to accept inputs in the RGB
-color space. Default value is 0.
-
-
-
-
Be aware that frames are taken from each input video in timestamp
-order, hence, if their initial timestamps differ, it is a a good idea
-to pass the two inputs through a setpts=PTS-STARTPTS filter to
-have them begin in the same zero timestamp, as it does the example for
-the movie filter.
-
-
Follow some examples:
-
# draw the overlay at 10 pixels from the bottom right
-# corner of the main video.
-overlay=main_w-overlay_w-10:main_h-overlay_h-10
-
-# insert a transparent PNG logo in the bottom left corner of the input
-movie=logo.png [logo];
-[in][logo] overlay=10:main_h-overlay_h-10 [out]
-
-# insert 2 different transparent PNG logos (second logo on bottom
-# right corner):
-movie=logo1.png [logo1];
-movie=logo2.png [logo2];
-[in][logo1] overlay=10:H-h-10 [in+logo1];
-[in+logo1][logo2] overlay=W-w-10:H-h-10 [out]
-
-# add a transparent color layer on top of the main video,
-# WxH specifies the size of the main input to the overlay filter
-color=red.3:WxH [over]; [in][over] overlay [out]
-
-
-
You can chain together more overlays but the efficiency of such
-approach is yet to be tested.
-
Add paddings to the input image, and places the original input at the
-given coordinates x, y.
-
-
It accepts the following parameters:
-width:height:x:y:color.
-
-
The parameters width, height, x, and y are
-expressions containing the following constants:
-
-
-
‘in_w, in_h’
-
the input video width and height
-
-
-
‘iw, ih’
-
same as in_w and in_h
-
-
-
‘out_w, out_h’
-
the output width and height, that is the size of the padded area as
-specified by the width and height expressions
-
-
-
‘ow, oh’
-
same as out_w and out_h
-
-
-
‘x, y’
-
x and y offsets as specified by the x and y
-expressions, or NAN if not yet specified
-
-
-
‘a’
-
same as iw / ih
-
-
-
‘sar’
-
input sample aspect ratio
-
-
-
‘dar’
-
input display aspect ratio, it is the same as (iw / ih) * sar
-
-
-
‘hsub, vsub’
-
horizontal and vertical chroma subsample values. For example for the
-pixel format "yuv422p" hsub is 2 and vsub is 1.
-
-
-
-
Follows the description of the accepted parameters.
-
-
-
‘width, height’
-
-
Specify the size of the output image with the paddings added. If the
-value for width or height is 0, the corresponding input size
-is used for the output.
-
-
The width expression can reference the value set by the
-height expression, and vice versa.
-
-
The default value of width and height is 0.
-
-
-
‘x, y’
-
-
Specify the offsets where to place the input image in the padded area
-with respect to the top/left border of the output image.
-
-
The x expression can reference the value set by the y
-expression, and vice versa.
-
-
The default value of x and y is 0.
-
-
-
‘color’
-
-
Specify the color of the padded area, it can be the name of a color
-(case insensitive match) or a 0xRRGGBB[AA] sequence.
-
-
The default value of color is "black".
-
-
-
-
-
Some examples follow:
-
-
# Add paddings with color "violet" to the input video. Output video
-# size is 640x480, the top-left corner of the input video is placed at
-# column 0, row 40.
-pad=640:480:0:40:violet
-
-# pad the input to get an output with dimensions increased bt 3/2,
-# and put the input video at the center of the padded area
-pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
-
-# pad the input to get a squared output with size equal to the maximum
-# value between the input width and height, and put the input video at
-# the center of the padded area
-pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
-
-# pad the input to get a final w/h ratio of 16:9
-pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
-
-# for anamorphic video, in order to set the output display aspect ratio,
-# it is necessary to use sar in the expression, according to the relation:
-# (ih * X / ih) * sar = output_dar
-# X = output_dar / sar
-pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2"
-
-# double output size and put the input video in the bottom-right
-# corner of the output padded area
-pad="2*iw:2*ih:ow-iw:oh-ih"
-
Scale the input video to width:height[:interl={1|-1}] and/or convert the image format.
-
-
The parameters width and height are expressions containing
-the following constants:
-
-
-
‘in_w, in_h’
-
the input width and height
-
-
-
‘iw, ih’
-
same as in_w and in_h
-
-
-
‘out_w, out_h’
-
the output (cropped) width and height
-
-
-
‘ow, oh’
-
same as out_w and out_h
-
-
-
‘a’
-
same as iw / ih
-
-
-
‘sar’
-
input sample aspect ratio
-
-
-
‘dar’
-
input display aspect ratio, it is the same as (iw / ih) * sar
-
-
-
‘hsub, vsub’
-
horizontal and vertical chroma subsample values. For example for the
-pixel format "yuv422p" hsub is 2 and vsub is 1.
-
-
-
-
If the input image format is different from the format requested by
-the next filter, the scale filter will convert the input to the
-requested format.
-
-
If the value for width or height is 0, the respective input
-size is used for the output.
-
-
If the value for width or height is -1, the scale filter will
-use, for the respective output size, a value that maintains the aspect
-ratio of the input image.
-
-
The default value of width and height is 0.
-
-
Valid values for the optional parameter interl are:
-
-
-
‘1’
-
force interlaced aware scaling
-
-
-
‘-1’
-
select interlaced aware scaling depending on whether the source frames
-are flagged as interlaced or not
-
-
-
-
Some examples follow:
-
# scale the input video to a size of 200x100.
-scale=200:100
-
-# scale the input to 2x
-scale=2*iw:2*ih
-# the above is the same as
-scale=2*in_w:2*in_h
-
-# scale the input to half size
-scale=iw/2:ih/2
-
-# increase the width, and set the height to the same size
-scale=3/2*iw:ow
-
-# seek for Greek harmony
-scale=iw:1/PHI*iw
-scale=ih*PHI:ih
-
-# increase the height, and set the width to 3/2 of the height
-scale=3/2*oh:3/5*ih
-
-# increase the size, but make the size a multiple of the chroma
-scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
-
-# increase the width to a maximum of 500 pixels, keep the same input aspect ratio
-scale='min(500\, iw*3/2):-1'
-
It accepts in input an expression, which is evaluated for each input
-frame. If the expression is evaluated to a non-zero value, the frame
-is selected and passed to the output, otherwise it is discarded.
-
-
The expression can contain the following constants:
-
-
-
‘n’
-
the sequential number of the filtered frame, starting from 0
-
-
-
‘selected_n’
-
the sequential number of the selected frame, starting from 0
-
-
-
‘prev_selected_n’
-
the sequential number of the last selected frame, NAN if undefined
-
-
-
‘TB’
-
timebase of the input timestamps
-
-
-
‘pts’
-
the PTS (Presentation TimeStamp) of the filtered video frame,
-expressed in TB units, NAN if undefined
-
-
-
‘t’
-
the PTS (Presentation TimeStamp) of the filtered video frame,
-expressed in seconds, NAN if undefined
-
-
-
‘prev_pts’
-
the PTS of the previously filtered video frame, NAN if undefined
-
-
-
‘prev_selected_pts’
-
the PTS of the last previously filtered video frame, NAN if undefined
-
-
-
‘prev_selected_t’
-
the PTS of the last previously selected video frame, NAN if undefined
-
-
-
‘start_pts’
-
the PTS of the first video frame in the video, NAN if undefined
-
-
-
‘start_t’
-
the time of the first video frame in the video, NAN if undefined
-
-
-
‘pict_type’
-
the type of the filtered frame, can assume one of the following
-values:
-
-
‘I’
-
‘P’
-
‘B’
-
‘S’
-
‘SI’
-
‘SP’
-
‘BI’
-
-
-
-
‘interlace_type’
-
the frame interlace type, can assume one of the following values:
-
-
‘PROGRESSIVE’
-
the frame is progressive (not interlaced)
-
-
‘TOPFIRST’
-
the frame is top-field-first
-
-
‘BOTTOMFIRST’
-
the frame is bottom-field-first
-
-
-
-
-
‘key’
-
1 if the filtered frame is a key-frame, 0 otherwise
-
-
-
‘pos’
-
the position in the file of the filtered frame, -1 if the information
-is not available (e.g. for synthetic video)
-
-
-
-
The default value of the select expression is "1".
-
-
Some examples follow:
-
-
# select all frames in input
-select
-
-# the above is the same as:
-select=1
-
-# skip all frames:
-select=0
-
-# select only I-frames
-select='eq(pict_type\,I)'
-
-# select one frame every 100
-select='not(mod(n\,100))'
-
-# select only frames contained in the 10-20 time interval
-select='gte(t\,10)*lte(t\,20)'
-
-# select only I frames contained in the 10-20 time interval
-select='gte(t\,10)*lte(t\,20)*eq(pict_type\,I)'
-
-# select frames with a minimum distance of 10 seconds
-select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
-
Set the Display Aspect Ratio for the filter output video.
-
-
This is done by changing the specified Sample (aka Pixel) Aspect
-Ratio, according to the following equation:
-DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR
-
-
Keep in mind that this filter does not modify the pixel dimensions of
-the video frame. Also the display aspect ratio set by this filter may
-be changed by later filters in the filterchain, e.g. in case of
-scaling or if another "setdar" or a "setsar" filter is applied.
-
-
The filter accepts a parameter string which represents the wanted
-display aspect ratio.
-The parameter can be a floating point number string, or an expression
-of the form num:den, where num and den are the
-numerator and denominator of the aspect ratio.
-If the parameter is not specified, it is assumed the value "0:1".
-
-
For example to change the display aspect ratio to 16:9, specify:
-
setdar=16:9
-# the above is equivalent to
-setdar=1.77777
-
Set the Sample (aka Pixel) Aspect Ratio for the filter output video.
-
-
Note that as a consequence of the application of this filter, the
-output display aspect ratio will change according to the following
-equation:
-DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR
-
-
Keep in mind that the sample aspect ratio set by this filter may be
-changed by later filters in the filterchain, e.g. if another "setsar"
-or a "setdar" filter is applied.
-
-
The filter accepts a parameter string which represents the wanted
-sample aspect ratio.
-The parameter can be a floating point number string, or an expression
-of the form num:den, where num and den are the
-numerator and denominator of the aspect ratio.
-If the parameter is not specified, it is assumed the value "0:1".
-
-
For example to change the sample aspect ratio to 10:11, specify:
-
Set the timebase to use for the output frames timestamps.
-It is mainly useful for testing timebase configuration.
-
-
It accepts in input an arithmetic expression representing a rational.
-The expression can contain the constants "AVTB" (the
-default timebase), and "intb" (the input timebase).
-
-
The default value for the input is "intb".
-
-
Follow some examples.
-
-
# set the timebase to 1/25
-settb=1/25
-
-# set the timebase to 1/10
-settb=0.1
-
-#set the timebase to 1001/1000
-settb=1+0.001
-
-#set the timebase to 2*intb
-settb=2*intb
-
-#set the default timebase value
-settb=AVTB
-
Show a line containing various information for each input video frame.
-The input video is not modified.
-
-
The shown line contains a sequence of key/value pairs of the form
-key:value.
-
-
A description of each shown parameter follows:
-
-
-
‘n’
-
sequential number of the input frame, starting from 0
-
-
-
‘pts’
-
Presentation TimeStamp of the input frame, expressed as a number of
-time base units. The time base unit depends on the filter input pad.
-
-
-
‘pts_time’
-
Presentation TimeStamp of the input frame, expressed as a number of
-seconds
-
-
-
‘pos’
-
position of the frame in the input stream, -1 if this information in
-unavailable and/or meaningless (for example in case of synthetic video)
-
-
-
‘fmt’
-
pixel format name
-
-
-
‘sar’
-
sample aspect ratio of the input frame, expressed in the form
-num/den
-
-
-
‘s’
-
size of the input frame, expressed in the form
-widthxheight
-
-
-
‘i’
-
interlaced mode ("P" for "progressive", "T" for top field first, "B"
-for bottom field first)
-
-
-
‘iskey’
-
1 if the frame is a key frame, 0 otherwise
-
-
-
‘type’
-
picture type of the input frame ("I" for an I-frame, "P" for a
-P-frame, "B" for a B-frame, "?" for unknown type).
-Check also the documentation of the AVPictureType enum and of
-the av_get_picture_type_char function defined in
-‘libavutil/avutil.h’.
-
-
-
‘checksum’
-
Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame
-
-
-
‘plane_checksum’
-
Adler-32 checksum (printed in hexadecimal) of each plane of the input frame,
-expressed in the form "[c0c1c2c3]"
-
Select the most representative frame in a given sequence of consecutive frames.
-
-
It accepts as argument the frames batch size to analyze (default N=100);
-in a set of N frames, the filter will pick one of them, and then handle
-the next batch of N frames until the end.
-
-
Since the filter keeps track of the whole frames sequence, a bigger N
-value will result in a higher memory usage, so a high value is not recommended.
-
-
The following example extract one picture each 50 frames:
-
thumbnail=50
-
-
-
Complete example of a thumbnail creation with ffmpeg:
-
It accepts the following parameters:
-luma_msize_x:luma_msize_y:luma_amount:chroma_msize_x:chroma_msize_y:chroma_amount
-
-
Negative values for the amount will blur the input video, while positive
-values will sharpen. All parameters are optional and default to the
-equivalent of the string ’5:5:1.0:5:5:0.0’.
-
-
-
‘luma_msize_x’
-
Set the luma matrix horizontal size. It can be an integer between 3
-and 13, default value is 5.
-
-
-
‘luma_msize_y’
-
Set the luma matrix vertical size. It can be an integer between 3
-and 13, default value is 5.
-
-
-
‘luma_amount’
-
Set the luma effect strength. It can be a float number between -2.0
-and 5.0, default value is 1.0.
-
-
-
‘chroma_msize_x’
-
Set the chroma matrix horizontal size. It can be an integer between 3
-and 13, default value is 5.
-
-
-
‘chroma_msize_y’
-
Set the chroma matrix vertical size. It can be an integer between 3
-and 13, default value is 5.
-
-
-
‘chroma_amount’
-
Set the chroma effect strength. It can be a float number between -2.0
-and 5.0, default value is 0.0.
-
-
-
-
-
# Strong luma sharpen effect parameters
-unsharp=7:7:2.5
-
-# Strong blur of both luma and chroma parameters
-unsharp=7:7:-2:7:7:-2
-
-# Use the default values with ffmpeg
-ffmpeg -i in.avi -vf "unsharp" out.mp4
-
Buffer video frames, and make them available to the filter chain.
-
-
This source is mainly intended for a programmatic use, in particular
-through the interface defined in ‘libavfilter/vsrc_buffer.h’.
-
-
It accepts the following parameters:
-width:height:pix_fmt_string:timebase_num:timebase_den:sample_aspect_ratio_num:sample_aspect_ratio.den:scale_params
-
-
All the parameters but scale_params need to be explicitly
-defined.
-
-
Follows the list of the accepted parameters.
-
-
-
‘width, height’
-
Specify the width and height of the buffered video frames.
-
-
-
‘pix_fmt_string’
-
A string representing the pixel format of the buffered video frames.
-It may be a number corresponding to a pixel format, or a pixel format
-name.
-
-
-
‘timebase_num, timebase_den’
-
Specify numerator and denomitor of the timebase assumed by the
-timestamps of the buffered frames.
-
Specify numerator and denominator of the sample aspect ratio assumed
-by the video frames.
-
-
-
‘scale_params’
-
Specify the optional parameters to be used for the scale filter which
-is automatically inserted when an input change is detected in the
-input size or format.
-
-
-
-
For example:
-
buffer=320:240:yuv410p:1:24:1:1
-
-
-
will instruct the source to accept video frames with size 320x240 and
-with format "yuv410p", assuming 1/24 as the timestamps timebase and
-square pixels (1:1 sample aspect ratio).
-Since the pixel format with name "yuv410p" corresponds to the number 6
-(check the enum PixelFormat definition in ‘libavutil/pixfmt.h’),
-this example corresponds to:
-
Create a pattern generated by an elementary cellular automaton.
-
-
The initial state of the cellular automaton can be defined through the
-‘filename’, and ‘pattern’ options. If such options are
-not specified an initial state is created randomly.
-
-
At each new frame a new row in the video is filled with the result of
-the cellular automaton next generation. The behavior when the whole
-frame is filled is defined by the ‘scroll’ option.
-
-
This source accepts a list of options in the form of
-key=value pairs separated by ":". A description of the
-accepted options follows.
-
-
-
‘filename, f’
-
Read the initial cellular automaton state, i.e. the starting row, from
-the specified file.
-In the file, each non-whitespace character is considered an alive
-cell, a newline will terminate the row, and further characters in the
-file will be ignored.
-
-
-
‘pattern, p’
-
Read the initial cellular automaton state, i.e. the starting row, from
-the specified string.
-
-
Each non-whitespace character in the string is considered an alive
-cell, a newline will terminate the row, and further characters in the
-string will be ignored.
-
-
-
‘rate, r’
-
Set the video rate, that is the number of frames generated per second.
-Default is 25.
-
-
-
‘random_fill_ratio, ratio’
-
Set the random fill ratio for the initial cellular automaton row. It
-is a floating point number value ranging from 0 to 1, defaults to
-1/PHI.
-
-
This option is ignored when a file or a pattern is specified.
-
-
-
‘random_seed, seed’
-
Set the seed for filling randomly the initial row, must be an integer
-included between 0 and UINT32_MAX. If not specified, or if explicitly
-set to -1, the filter will try to use a good random seed on a best
-effort basis.
-
-
-
‘rule’
-
Set the cellular automaton rule, it is a number ranging from 0 to 255.
-Default value is 110.
-
-
-
‘size, s’
-
Set the size of the output video.
-
-
If ‘filename’ or ‘pattern’ is specified, the size is set
-by default to the width of the specified initial state row, and the
-height is set to width * PHI.
-
-
If ‘size’ is set, it must contain the width of the specified
-pattern string, and the specified pattern will be centered in the
-larger row.
-
-
If a filename or a pattern string is not specified, the size value
-defaults to "320x518" (used for a randomly generated initial state).
-
-
-
‘scroll’
-
If set to 1, scroll the output upward when all the rows in the output
-have been already filled. If set to 0, the new generated row will be
-written over the top row just after the bottom row is filled.
-Defaults to 1.
-
-
-
‘start_full, full’
-
If set to 1, completely fill the output with generated rows before
-outputting the first frame.
-This is the default behavior, for disabling set the value to 0.
-
-
-
‘stitch’
-
If set to 1, stitch the left and right row edges together.
-This is the default behavior, for disabling set the value to 0.
-
It accepts the following parameters:
-color:frame_size:frame_rate
-
-
Follows the description of the accepted parameters.
-
-
-
‘color’
-
Specify the color of the source. It can be the name of a color (case
-insensitive match) or a 0xRRGGBB[AA] sequence, possibly followed by an
-alpha specifier. The default value is "black".
-
-
-
‘frame_size’
-
Specify the size of the sourced video, it may be a string of the form
-widthxheight, or the name of a size abbreviation. The
-default value is "320x240".
-
-
-
‘frame_rate’
-
Specify the frame rate of the sourced video, as the number of frames
-generated per second. It has to be a string in the format
-frame_rate_num/frame_rate_den, an integer number, a float
-number or a valid video frame rate abbreviation. The default value is
-"25".
-
-
-
-
-
For example the following graph description will generate a red source
-with an opacity of 0.2, with size "qcif" and a frame rate of 10
-frames per second, which will be overlayed over the source connected
-to the pad with identifier "in".
-
It accepts the syntax: movie_name[:options] where
-movie_name is the name of the resource to read (not necessarily
-a file but also a device or a stream accessed through some protocol),
-and options is an optional sequence of key=value
-pairs, separated by ":".
-
-
The description of the accepted options follows.
-
-
-
‘format_name, f’
-
Specifies the format assumed for the movie to read, and can be either
-the name of a container or an input device. If not specified the
-format is guessed from movie_name or by probing.
-
-
-
‘seek_point, sp’
-
Specifies the seek point in seconds, the frames will be output
-starting from this seek point, the parameter is evaluated with
-av_strtod so the numerical value may be suffixed by an IS
-postfix. Default value is "0".
-
-
-
‘stream_index, si’
-
Specifies the index of the video stream to read. If the value is -1,
-the best suited video stream will be automatically selected. Default
-value is "-1".
-
-
-
-
-
This filter allows to overlay a second video on top of main input of
-a filtergraph as shown in this graph:
-
# skip 3.2 seconds from the start of the avi file in.avi, and overlay it
-# on top of the input labelled as "in".
-movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [movie];
-[in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
-
-# read from a video4linux2 device, and overlay it on top of the input
-# labelled as "in"
-movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [movie];
-[in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
-
-
Generate various test patterns, as generated by the MPlayer test filter.
-
-
The size of the generated video is fixed, and is 256x256.
-This source is useful in particular for testing encoding features.
-
-
This source accepts an optional sequence of key=value pairs,
-separated by ":". The description of the accepted options follows.
-
-
-
‘rate, r’
-
Specify the frame rate of the sourced video, as the number of frames
-generated per second. It has to be a string in the format
-frame_rate_num/frame_rate_den, an integer number, a float
-number or a valid video frame rate abbreviation. The default value is
-"25".
-
-
-
‘duration, d’
-
Set the video duration of the sourced video. The accepted syntax is:
-
[-]HH[:MM[:SS[.m...]]]
-[-]S+[.m...]
-
-
See also the function av_parse_time().
-
-
If not specified, or the expressed duration is negative, the video is
-supposed to be generated forever.
-
-
-
‘test, t’
-
-
Set the number or the name of the test to perform. Supported tests are:
-
-
‘dc_luma’
-
‘dc_chroma’
-
‘freq_luma’
-
‘freq_chroma’
-
‘amp_luma’
-
‘amp_chroma’
-
‘cbp’
-
‘mv’
-
‘ring1’
-
‘ring2’
-
‘all’
-
-
-
Default value is "all", which will cycle through the list of all tests.
-
size is the size of the video to generate, may be a string of the
-form widthxheight or a frame size abbreviation.
-rate is the rate of the video to generate, may be a string of
-the form num/den or a frame rate abbreviation.
-src_name is the name to the frei0r source to load. For more
-information regarding frei0r and how to set the parameters read the
-section frei0r in the description of the video filters.
-
-
Some examples follow:
-
# generate a frei0r partik0l source with size 200x200 and frame rate 10
-# which is overlayed on the overlay filter main input
-frei0r_src=200x200:10:partik0l=1234 [overlay]; [in][overlay] overlay
-
This source is based on a generalization of John Conway’s life game.
-
-
The sourced input represents a life grid, each pixel represents a cell
-which can be in one of two possible states, alive or dead. Every cell
-interacts with its eight neighbours, which are the cells that are
-horizontally, vertically, or diagonally adjacent.
-
-
At each interaction the grid evolves according to the adopted rule,
-which specifies the number of neighbor alive cells which will make a
-cell stay alive or born. The ‘rule’ option allows to specify
-the rule to adopt.
-
-
This source accepts a list of options in the form of
-key=value pairs separated by ":". A description of the
-accepted options follows.
-
-
-
‘filename, f’
-
Set the file from which to read the initial grid state. In the file,
-each non-whitespace character is considered an alive cell, and newline
-is used to delimit the end of each row.
-
-
If this option is not specified, the initial grid is generated
-randomly.
-
-
-
‘rate, r’
-
Set the video rate, that is the number of frames generated per second.
-Default is 25.
-
-
-
‘random_fill_ratio, ratio’
-
Set the random fill ratio for the initial random grid. It is a
-floating point number value ranging from 0 to 1, defaults to 1/PHI.
-It is ignored when a file is specified.
-
-
-
‘random_seed, seed’
-
Set the seed for filling the initial random grid, must be an integer
-included between 0 and UINT32_MAX. If not specified, or if explicitly
-set to -1, the filter will try to use a good random seed on a best
-effort basis.
-
-
-
‘rule’
-
Set the life rule.
-
-
A rule can be specified with a code of the kind "SNS/BNB",
-where NS and NB are sequences of numbers in the range 0-8,
-NS specifies the number of alive neighbor cells which make a
-live cell stay alive, and NB the number of alive neighbor cells
-which make a dead cell to become alive (i.e. to "born").
-"s" and "b" can be used in place of "S" and "B", respectively.
-
-
Alternatively a rule can be specified by an 18-bits integer. The 9
-high order bits are used to encode the next cell state if it is alive
-for each number of neighbor alive cells, the low order bits specify
-the rule for "borning" new cells. Higher order bits encode for an
-higher number of neighbor cells.
-For example the number 6153 = (12<<9)+9 specifies a stay alive
-rule of 12 and a born rule of 9, which corresponds to "S23/B03".
-
-
Default value is "S23/B3", which is the original Conway’s game of life
-rule, and will keep a cell alive if it has 2 or 3 neighbor alive
-cells, and will born a new cell if there are three alive cells around
-a dead cell.
-
-
-
‘size, s’
-
Set the size of the output video.
-
-
If ‘filename’ is specified, the size is set by default to the
-same size of the input file. If ‘size’ is set, it must contain
-the size specified in the input file, and the initial grid defined in
-that file is centered in the larger resulting area.
-
-
If a filename is not specified, the size value defaults to "320x240"
-(used for a randomly generated initial grid).
-
-
-
‘stitch’
-
If set to 1, stitch the left and right grid edges together, and the
-top and bottom edges also. Defaults to 1.
-
-
-
‘mold’
-
Set cell mold speed. If set, a dead cell will go from ‘death_color’ to
-‘mold_color’ with a step of ‘mold’. ‘mold’ can have a
-value from 0 to 255.
-
-
-
‘life_color’
-
Set the color of living (or new born) cells.
-
-
-
‘death_color’
-
Set the color of dead cells. If ‘mold’ is set, this is the first color
-used to represent a dead cell.
-
-
-
‘mold_color’
-
Set mold color, for definitely dead and moldy cells.
-
The nullsrc source returns unprocessed video frames. It is
-mainly useful to be employed in analysis / debugging tools, or as the
-source for filters which ignore the input data.
-
-
The rgbtestsrc source generates an RGB test pattern useful for
-detecting RGB vs BGR issues. You should see a red, green and blue
-stripe from top to bottom.
-
-
The testsrc source generates a test video pattern, showing a
-color pattern, a scrolling gradient and a timestamp. This is mainly
-intended for testing purposes.
-
-
These sources accept an optional sequence of key=value pairs,
-separated by ":". The description of the accepted options follows.
-
-
-
‘size, s’
-
Specify the size of the sourced video, it may be a string of the form
-widthxheight, or the name of a size abbreviation. The
-default value is "320x240".
-
-
-
‘rate, r’
-
Specify the frame rate of the sourced video, as the number of frames
-generated per second. It has to be a string in the format
-frame_rate_num/frame_rate_den, an integer number, a float
-number or a valid video frame rate abbreviation. The default value is
-"25".
-
-
-
‘sar’
-
Set the sample aspect ratio of the sourced video.
-
-
-
‘duration, d’
-
Set the video duration of the sourced video. The accepted syntax is:
-
[-]HH[:MM[:SS[.m...]]]
-[-]S+[.m...]
-
-
See also the function av_parse_time().
-
-
If not specified, or the expressed duration is negative, the video is
-supposed to be generated forever.
-
-
-
‘decimals, n’
-
Set the number of decimals to show in the timestamp, only used in the
-testsrc source.
-
-
The displayed timestamp value will correspond to the original
-timestamp value multiplied by the power of 10 of the specified
-value. Default value is 0.
-
-
-
-
For example the following:
-
testsrc=duration=5.3:size=qcif:rate=10
-
-
-
will generate a video with a duration of 5.3 seconds, with size
-176x144 and a frame rate of 10 frames per second.
-
-
If the input content is to be ignored, nullsrc can be used. The
-following command generates noise in the luminance plane by employing
-the mp=geq filter:
-
Buffer video frames, and make them available to the end of the filter
-graph.
-
-
This sink is mainly intended for a programmatic use, in particular
-through the interface defined in ‘libavfilter/buffersink.h’.
+
The FFmpeg developers.
-
It does not require a string parameter in input, but you need to
-specify a pointer to a list of supported pixel formats terminated by
--1 in the opaque parameter provided to avfilter_init_filter
-when initializing this sink.
+
For details about the authorship, see the Git history of the project
+(git://source.ffmpeg.org/ffmpeg), e.g. by typing the command
+git log in the FFmpeg source directory, or browsing the
+online repository at http://source.ffmpeg.org.
ffprobe gathers information from multimedia streams and prints it in
+human- and machine-readable fashion.
+
+
For example it can be used to check the format of the container used
+by a multimedia stream and the format and type of each media stream
+contained in it.
+
+
If a filename is specified in input, ffprobe will try to open and
+probe the file content. If the file cannot be opened or recognized as
+a multimedia file, a positive exit code is returned.
+
+
ffprobe may be employed both as a standalone application or in
+combination with a textual filter, which may perform more
+sophisticated processing, e.g. statistical processing or plotting.
+
+
Options are used to list some of the formats supported by ffprobe or
+for specifying which information to display, and for setting how
+ffprobe will show it.
+
+
ffprobe output is designed to be easily parsable by a textual filter,
+and consists of one or more sections of a form defined by the selected
+writer, which is specified by the ‘print_format’ option.
+
+
Sections may contain other nested sections, and are identified by a
+name (which may be shared by other sections), and an unique
+name. See the output of ‘sections’.
+
+
Metadata tags stored in the container or in the streams are recognized
+and printed in the corresponding "FORMAT", "STREAM" or "PROGRAM_STREAM"
+section.
+
All the numerical options, if not specified otherwise, accept a string
+representing a number as input, which may be followed by one of the SI
+unit prefixes, for example: ’K’, ’M’, or ’G’.
+
+
If ’i’ is appended to the SI unit prefix, the complete prefix will be
+interpreted as a unit prefix for binary multiplies, which are based on
+powers of 1024 instead of powers of 1000. Appending ’B’ to the SI unit
+prefix multiplies the value by 8. This allows using, for example:
+’KB’, ’MiB’, ’G’ and ’B’ as number suffixes.
+
+
Options which do not take arguments are boolean options, and set the
+corresponding value to true. They can be set to false by prefixing
+the option name with "no". For example using "-nofoo"
+will set the boolean option with name "foo" to false.
+
Some options are applied per-stream, e.g. bitrate or codec. Stream specifiers
+are used to precisely specify which stream(s) a given option belongs to.
+
+
A stream specifier is a string generally appended to the option name and
+separated from it by a colon. E.g. -codec:a:1 ac3 contains the
+a:1 stream specifier, which matches the second audio stream. Therefore, it
+would select the ac3 codec for the second audio stream.
+
+
A stream specifier can match several streams, so that the option is applied to all
+of them. E.g. the stream specifier in -b:a 128k matches all audio
+streams.
+
+
An empty stream specifier matches all streams. For example, -codec copy
+or -codec: copy would copy all the streams without reencoding.
+
+
Possible forms of stream specifiers are:
+
+
‘stream_index’
+
Matches the stream with this index. E.g. -threads:1 4 would set the
+thread count for the second stream to 4.
+
+
‘stream_type[:stream_index]’
+
stream_type is one of following: ’v’ for video, ’a’ for audio, ’s’ for subtitle,
+’d’ for data, and ’t’ for attachments. If stream_index is given, then it matches
+stream number stream_index of this type. Otherwise, it matches all
+streams of this type.
+
+
‘p:program_id[:stream_index]’
+
If stream_index is given, then it matches the stream with number stream_index
+in the program with the id program_id. Otherwise, it matches all streams in the
+program.
+
Show help. An optional parameter may be specified to print help about a specific
+item. If no argument is specified, only basic (non advanced) tool
+options are shown.
+
+
Possible values of arg are:
+
+
‘long’
+
Print advanced tool options in addition to the basic tool options.
+
+
+
‘full’
+
Print complete list of options, including shared and private options
+for encoders, decoders, demuxers, muxers, filters, etc.
+
+
+
‘decoder=decoder_name’
+
Print detailed information about the decoder named decoder_name. Use the
+‘-decoders’ option to get a list of all decoders.
+
+
+
‘encoder=encoder_name’
+
Print detailed information about the encoder named encoder_name. Use the
+‘-encoders’ option to get a list of all encoders.
+
+
+
‘demuxer=demuxer_name’
+
Print detailed information about the demuxer named demuxer_name. Use the
+‘-formats’ option to get a list of all demuxers and muxers.
+
+
+
‘muxer=muxer_name’
+
Print detailed information about the muxer named muxer_name. Use the
+‘-formats’ option to get a list of all muxers and demuxers.
+
+
+
‘filter=filter_name’
+
Print detailed information about the filter name filter_name. Use the
+‘-filters’ option to get a list of all filters.
+
+
+
+
+
‘-version’
+
Show version.
+
+
+
‘-formats’
+
Show available formats.
+
+
+
‘-codecs’
+
Show all codecs known to libavcodec.
+
+
Note that the term ’codec’ is used throughout this documentation as a shortcut
+for what is more correctly called a media bitstream format.
+
+
+
‘-decoders’
+
Show available decoders.
+
+
+
‘-encoders’
+
Show all available encoders.
+
+
+
‘-bsfs’
+
Show available bitstream filters.
+
+
+
‘-protocols’
+
Show available protocols.
+
+
+
‘-filters’
+
Show available libavfilter filters.
+
+
+
‘-pix_fmts’
+
Show available pixel formats.
+
+
+
‘-sample_fmts’
+
Show available sample formats.
+
+
+
‘-layouts’
+
Show channel names and standard channel layouts.
+
Set the logging level used by the library.
+Adding "repeat+" indicates that repeated log output should not be compressed
+to the first line and the "Last message repeated n times" line will be
+omitted. "repeat" can also be used alone.
+If "repeat" is used alone, and with no prior loglevel set, the default
+loglevel will be used. If multiple loglevel parameters are given, using
+’repeat’ will not change the loglevel.
+loglevel is a number or a string containing one of the following values:
+
+
‘quiet’
+
Show nothing at all; be silent.
+
+
‘panic’
+
Only show fatal errors which could lead the process to crash, such as
+and assert failure. This is not currently used for anything.
+
+
‘fatal’
+
Only show fatal errors. These are errors after which the process absolutely
+cannot continue after.
+
+
‘error’
+
Show all errors, including ones which can be recovered from.
+
+
‘warning’
+
Show all warnings and errors. Any message related to possibly
+incorrect or unexpected events will be shown.
+
+
‘info’
+
Show informative messages during processing. This is in addition to
+warnings and errors. This is the default value.
+
+
‘verbose’
+
Same as info, except more verbose.
+
+
‘debug’
+
Show everything, including debugging information.
+
+
+
+
By default the program logs to stderr, if coloring is supported by the
+terminal, colors are used to mark errors and warnings. Log coloring
+can be disabled setting the environment variable
+AV_LOG_FORCE_NOCOLOR or NO_COLOR, or can be forced setting
+the environment variable AV_LOG_FORCE_COLOR.
+The use of the environment variable NO_COLOR is deprecated and
+will be dropped in a following FFmpeg version.
+
+
+
‘-report’
+
Dump full command line and console output to a file named
+program-YYYYMMDD-HHMMSS.log in the current
+directory.
+This file can be useful for bug reports.
+It also implies -loglevel verbose.
+
+
Setting the environment variable FFREPORT to any value has the
+same effect. If the value is a ’:’-separated key=value sequence, these
+options will affect the report; options values must be escaped if they
+contain special characters or the options delimiter ’:’ (see the
+“Quoting and escaping” section in the ffmpeg-utils manual). The
+following option is recognized:
+
+
‘file’
+
set the file name to use for the report; %p is expanded to the name
+of the program, %t is expanded to a timestamp, %% is expanded
+to a plain %
+
+
+
+
Errors in parsing the environment variable are not fatal, and will not
+appear in the report.
+
+
+
‘-cpuflags flags (global)’
+
Allows setting and clearing cpu flags. This option is intended
+for testing. Do not use it unless you know what you’re doing.
+
Set OpenCL environment options. This option is only available when
+FFmpeg has been compiled with --enable-opencl.
+
+
options must be a list of key=value option pairs
+separated by ’:’. See the “OpenCL Options” section in the
+ffmpeg-utils manual for the list of supported options.
+
These options are provided directly by the libavformat, libavdevice and
+libavcodec libraries. To see the list of available AVOptions, use the
+‘-help’ option. They are separated into two categories:
+
+
‘generic’
+
These options can be set for any container, codec or device. Generic options
+are listed under AVFormatContext options for containers/devices and under
+AVCodecContext options for codecs.
+
+
‘private’
+
These options are specific to the given container, device or codec. Private
+options are listed under their corresponding containers/devices/codecs.
+
+
+
+
For example to write an ID3v2.3 header instead of a default ID3v2.4 to
+an MP3 file, use the ‘id3v2_version’ private option of the MP3
+muxer:
+
ffmpeg -i input.flac -id3v2_version 3 out.mp3
+
+
+
All codec AVOptions are per-stream, and thus a stream specifier
+should be attached to them.
+
+
Note: the ‘-nooption’ syntax cannot be used for boolean
+AVOptions, use ‘-option 0’/‘-option 1’.
+
+
Note: the old undocumented way of specifying per-stream AVOptions by
+prepending v/a/s to the options name is now obsolete and will be
+removed soon.
+
Use SI prefixes for the displayed values.
+Unless the "-byte_binary_prefix" option is used all the prefixes
+are decimal.
+
+
+
‘-byte_binary_prefix’
+
Force the use of binary prefixes for byte values.
+
+
+
‘-sexagesimal’
+
Use sexagesimal format HH:MM:SS.MICROSECONDS for time values.
+
+
+
‘-pretty’
+
Prettify the format of the displayed values, it corresponds to the
+options "-unit -prefix -byte_binary_prefix -sexagesimal".
+
+
+
‘-of, -print_format writer_name[=writer_options]’
+
Set the output printing format.
+
+
writer_name specifies the name of the writer, and
+writer_options specifies the options to be passed to the writer.
+
+
For example for printing the output in JSON format, specify:
+
-print_format json
+
+
+
For more details on the available output printing formats, see the
+Writers section below.
+
+
+
‘-sections’
+
Print sections structure and section information, and exit. The output
+is not meant to be parsed by a machine.
+
+
+
‘-select_streams stream_specifier’
+
Select only the streams specified by stream_specifier. This
+option affects only the options related to streams
+(e.g. show_streams, show_packets, etc.).
+
+
For example to show only audio streams, you can use the command:
+
ffprobe -show_streams -select_streams a INPUT
+
+
+
To show only video packets belonging to the video stream with index 1:
+
ffprobe -show_packets -select_streams v:1 INPUT
+
+
+
+
‘-show_data’
+
Show payload data, as a hexadecimal and ASCII dump. Coupled with
+‘-show_packets’, it will dump the packets’ data. Coupled with
+‘-show_streams’, it will dump the codec extradata.
+
+
The dump is printed as the "data" field. It may contain newlines.
+
+
+
‘-show_error’
+
Show information about the error found when trying to probe the input.
+
+
The error information is printed within a section with name "ERROR".
+
+
+
‘-show_format’
+
Show information about the container format of the input multimedia
+stream.
+
+
All the container format information is printed within a section with
+name "FORMAT".
+
+
+
‘-show_format_entry name’
+
Like ‘-show_format’, but only prints the specified entry of the
+container format information, rather than all. This option may be given more
+than once, then all specified entries will be shown.
+
+
This option is deprecated, use show_entries instead.
+
+
+
‘-show_entries section_entries’
+
Set list of entries to show.
+
+
Entries are specified according to the following
+syntax. section_entries contains a list of section entries
+separated by :. Each section entry is composed by a section
+name (or unique name), optionally followed by a list of entries local
+to that section, separated by ,.
+
+
If section name is specified but is followed by no =, all
+entries are printed to output, together with all the contained
+sections. Otherwise only the entries specified in the local section
+entries list are printed. In particular, if = is specified but
+the list of local entries is empty, then no entries will be shown for
+that section.
+
+
Note that the order of specification of the local section entries is
+not honored in the output, and the usual display order will be
+retained.
+
For example, to show only the index and type of each stream, and the PTS
+time, duration time, and stream index of the packets, you can specify
+the argument:
+
To show all the entries in the section "format", but only the codec
+type in the section "stream", specify the argument:
+
format : stream=codec_type
+
+
+
To show all the tags in the stream and format sections:
+
format_tags : format_tags
+
+
+
To show only the title tag (if available) in the stream
+sections:
+
stream_tags=title
+
+
+
+
‘-show_packets’
+
Show information about each packet contained in the input multimedia
+stream.
+
+
The information for each single packet is printed within a dedicated
+section with name "PACKET".
+
+
+
‘-show_frames’
+
Show information about each frame contained in the input multimedia
+stream.
+
+
The information for each single frame is printed within a dedicated
+section with name "FRAME".
+
+
+
‘-show_streams’
+
Show information about each media stream contained in the input
+multimedia stream.
+
+
Each media stream information is printed within a dedicated section
+with name "STREAM".
+
+
+
‘-show_programs’
+
Show information about programs and their streams contained in the input
+multimedia stream.
+
+
Each media stream information is printed within a dedicated section
+with name "PROGRAM_STREAM".
+
+
+
‘-show_chapters’
+
Show information about chapters stored in the format.
+
+
Each chapter is printed within a dedicated section with name "CHAPTER".
+
+
+
‘-count_frames’
+
Count the number of frames per stream and report it in the
+corresponding stream section.
+
+
+
‘-count_packets’
+
Count the number of packets per stream and report it in the
+corresponding stream section.
+
+
+
‘-read_intervals read_intervals’
+
+
Read only the specified intervals. read_intervals must be a
+sequence of interval specifications separated by ",".
+ffprobe will seek to the interval starting point, and will
+continue reading from that.
+
+
Each interval is specified by two optional parts, separated by "%".
+
+
The first part specifies the interval start position. It is
+interpreted as an abolute position, or as a relative offset from the
+current position if it is preceded by the "+" character. If this first
+part is not specified, no seeking will be performed when reading this
+interval.
+
+
The second part specifies the interval end position. It is interpreted
+as an absolute position, or as a relative offset from the current
+position if it is preceded by the "+" character. If the offset
+specification starts with "#", it is interpreted as the number of
+packets to read (not including the flushing packets) from the interval
+start. If no second part is specified, the program will read until the
+end of the input.
+
+
Note that seeking is not accurate, thus the actual interval start
+point may be different from the specified position. Also, when an
+interval duration is specified, the absolute end time will be computed
+by adding the duration to the interval start point found by seeking
+the file, rather than to the specified start value.
+
+Seek to time 10, read packets until 20 seconds after the found seek
+point, then seek to position 01:30 (1 minute and thirty
+seconds) and read packets until position 01:45.
+
10%+20,01:30%01:45
+
+
+
+Read only 42 packets after seeking to position 01:23:
+
01:23%+#42
+
+
+
+Read only the first 20 seconds from the start:
+
%+20
+
+
+
+Read from the start until position 02:30:
+
%02:30
+
+
+
+
+
‘-show_private_data, -private’
+
Show private data, that is data depending on the format of the
+particular shown element.
+This option is enabled by default, but you may need to disable it
+for specific uses, for example when creating XSD-compliant XML output.
+
+
+
‘-show_program_version’
+
Show information related to program version.
+
+
Version information is printed within a section with name
+"PROGRAM_VERSION".
+
+
+
‘-show_library_versions’
+
Show information related to library versions.
+
+
Version information for each library is printed within a section with
+name "LIBRARY_VERSION".
+
+
+
‘-show_versions’
+
Show information related to program and library versions. This is the
+equivalent of setting both ‘-show_program_version’ and
+‘-show_library_versions’ options.
+
+
+
‘-bitexact’
+
Force bitexact output, useful to produce output which is not dependent
+on the specific build.
+
A writer defines the output format adopted by ffprobe, and will be
+used for printing all the parts of the output.
+
+
A writer may accept one or more arguments, which specify the options
+to adopt. The options are specified as a list of key=value
+pairs, separated by ":".
+
+
A description of the currently available writers follows.
+
The csv writer is equivalent to compact, but supports
+different defaults.
+
+
Each section is printed on a single line.
+If no option is specifid, the output has the form:
+
section|key1=val1| ... |keyN=valN
+
+
+
Metadata tags are printed in the corresponding "format" or "stream"
+section. A metadata tag key, if printed, is prefixed by the string
+"tag:".
+
+
The description of the accepted options follows.
+
+
+
‘item_sep, s’
+
Specify the character to use for separating fields in the output line.
+It must be a single printable character, it is "|" by default ("," for
+the csv writer).
+
+
+
‘nokey, nk’
+
If set to 1 specify not to print the key of each field. Its default
+value is 0 (1 for the csv writer).
+
+
+
‘escape, e’
+
Set the escape mode to use, default to "c" ("csv" for the csv
+writer).
+
+
It can assume one of the following values:
+
+
‘c’
+
Perform C-like escaping. Strings containing a newline (’\n’), carriage
+return (’\r’), a tab (’\t’), a form feed (’\f’), the escaping
+character (’\’) or the item separator character SEP are escaped using C-like fashioned
+escaping, so that a newline is converted to the sequence "\n", a
+carriage return to "\r", ’\’ to "\\" and the separator SEP is
+converted to "\SEP".
+
+
+
‘csv’
+
Perform CSV-like escaping, as described in RFC4180. Strings
+containing a newline (’\n’), a carriage return (’\r’), a double quote
+(’"’), or SEP are enclosed in double-quotes.
+
+
+
‘none’
+
Perform no escaping.
+
+
+
+
+
‘print_section, p’
+
Print the section name at the begin of each line if the value is
+1, disable it with value set to 0. Default value is
+1.
+
A free-form output where each line contains an explicit key=value, such as
+"streams.stream.3.tags.foo=bar". The output is shell escaped, so it can be
+directly embedded in sh scripts as long as the separator character is an
+alphanumeric character or an underscore (see sep_char option).
+
+
The description of the accepted options follows.
+
+
+
‘sep_char, s’
+
Separator character used to separate the chapter, the section name, IDs and
+potential tags in the printed field key.
+
+
Default value is ’.’.
+
+
+
‘hierarchical, h’
+
Specify if the section name specification should be hierarchical. If
+set to 1, and if there is more than one section in the current
+chapter, the section name will be prefixed by the name of the
+chapter. A value of 0 will disable this behavior.
+
+newline, ’\t’, ’\f’, ’\b’ and the following characters are escaped
+
+’\’ is the escape character
+
+’#’ is the comment indicator
+
+’=’ is the key/value separator
+
+’:’ is not used but usually parsed as key/value separator
+
+
+
This writer accepts options as a list of key=value pairs,
+separated by ":".
+
+
The description of the accepted options follows.
+
+
+
‘hierarchical, h’
+
Specify if the section name specification should be hierarchical. If
+set to 1, and if there is more than one section in the current
+chapter, the section name will be prefixed by the name of the
+chapter. A value of 0 will disable this behavior.
+
The XML output is described in the XML schema description file
+‘ffprobe.xsd’ installed in the FFmpeg datadir.
+
+
An updated version of the schema can be retrieved at the url
+http://www.ffmpeg.org/schema/ffprobe.xsd, which redirects to the
+latest schema committed into the FFmpeg development source code tree.
+
+
Note that the output issued will be compliant to the
+‘ffprobe.xsd’ schema only when no special global output options
+(‘unit’, ‘prefix’, ‘byte_binary_prefix’,
+‘sexagesimal’ etc.) are specified.
+
+
The description of the accepted options follows.
+
+
+
‘fully_qualified, q’
+
If set to 1 specify if the output should be fully qualified. Default
+value is 0.
+This is required for generating an XML file which can be validated
+through an XSD file.
+
+
+
‘xsd_compliant, x’
+
If set to 1 perform more checks for ensuring that the output is XSD
+compliant. Default value is 0.
+This option automatically sets ‘fully_qualified’ to 1.
+
FFmpeg adopts the following quoting and escaping mechanism, unless
+explicitly specified. The following rules are applied:
+
+
+
+' and \ are special characters (respectively used for
+quoting and escaping). In addition to them, there might be other
+special characters depending on the specific syntax where the escaping
+and quoting are employed.
+
+
+A special character is escaped by prefixing it with a ’\’.
+
+
+All characters enclosed between ” are included literally in the
+parsed string. The quote character ' itself cannot be quoted,
+so you may need to close the quote and escape it.
+
+
+Leading and trailing whitespaces, unless escaped or quoted, are
+removed from the parsed string.
+
+
+
Note that you may need to add a second level of escaping when using
+the command line or a script, which depends on the syntax of the
+adopted shell language.
+
+
The function av_get_token defined in
+‘libavutil/avstring.h’ can be used to parse a token quoted or
+escaped according to the rules defined above.
+
+
The tool ‘tools/ffescape’ in the FFmpeg source tree can be used
+to automatically quote or escape a string in a script.
+
If the value is "now" it takes the current time.
+
+
Time is local time unless Z is appended, in which case it is
+interpreted as UTC.
+If the year-month-day part is not specified it takes the current
+year-month-day.
+
There are two accepted syntaxes for expressing time duration.
+
+
[-][HH:]MM:SS[.m...]
+
+
+
HH expresses the number of hours, MM the number of minutes
+for a maximum of 2 digits, and SS the number of seconds for a
+maximum of 2 digits. The m at the end expresses decimal value for
+SS.
+
+
or
+
+
[-]S+[.m...]
+
+
+
S expresses the number of seconds, with the optional decimal part
+m.
+
+
In both expressions, the optional ‘-’ indicates negative duration.
+
Specify the frame rate of a video, expressed as the number of frames
+generated per second. It has to be a string in the format
+frame_rate_num/frame_rate_den, an integer number, a float
+number or a valid video frame rate abbreviation.
+
A ratio can be expressed as an expression, or in the form
+numerator:denominator.
+
+
Note that a ratio with infinite (1/0) or negative value is
+considered valid, so you should check on the returned value if you
+want to exclude those values.
+
+
The undefined value can be expressed using the "0:0" string.
+
It can be the name of a color as defined below (case insensitive match) or a
+[0x|#]RRGGBB[AA] sequence, possibly followed by @ and a string
+representing the alpha component.
+
+
The alpha component may be a string composed by "0x" followed by an
+hexadecimal number or a decimal number between 0.0 and 1.0, which
+represents the opacity value (‘0x00’ or ‘0.0’ means completely
+transparent, ‘0xff’ or ‘1.0’ completely opaque). If the alpha
+component is not specified then ‘0xff’ is assumed.
+
+
The string ‘random’ will result in a random color.
+
A channel layout specifies the spatial disposition of the channels in
+a multi-channel audio stream. To specify a channel layout, FFmpeg
+makes use of a special syntax.
+
+
Individual channels are identified by an id, as given by the table
+below:
+
+
‘FL’
+
front left
+
+
‘FR’
+
front right
+
+
‘FC’
+
front center
+
+
‘LFE’
+
low frequency
+
+
‘BL’
+
back left
+
+
‘BR’
+
back right
+
+
‘FLC’
+
front left-of-center
+
+
‘FRC’
+
front right-of-center
+
+
‘BC’
+
back center
+
+
‘SL’
+
side left
+
+
‘SR’
+
side right
+
+
‘TC’
+
top center
+
+
‘TFL’
+
top front left
+
+
‘TFC’
+
top front center
+
+
‘TFR’
+
top front right
+
+
‘TBL’
+
top back left
+
+
‘TBC’
+
top back center
+
+
‘TBR’
+
top back right
+
+
‘DL’
+
downmix left
+
+
‘DR’
+
downmix right
+
+
‘WL’
+
wide left
+
+
‘WR’
+
wide right
+
+
‘SDL’
+
surround direct left
+
+
‘SDR’
+
surround direct right
+
+
‘LFE2’
+
low frequency 2
+
+
+
+
Standard channel layout compositions can be specified by using the
+following identifiers:
+
+
‘mono’
+
FC
+
+
‘stereo’
+
FL+FR
+
+
‘2.1’
+
FL+FR+LFE
+
+
‘3.0’
+
FL+FR+FC
+
+
‘3.0(back)’
+
FL+FR+BC
+
+
‘4.0’
+
FL+FR+FC+BC
+
+
‘quad’
+
FL+FR+BL+BR
+
+
‘quad(side)’
+
FL+FR+SL+SR
+
+
‘3.1’
+
FL+FR+FC+LFE
+
+
‘5.0’
+
FL+FR+FC+BL+BR
+
+
‘5.0(side)’
+
FL+FR+FC+SL+SR
+
+
‘4.1’
+
FL+FR+FC+LFE+BC
+
+
‘5.1’
+
FL+FR+FC+LFE+BL+BR
+
+
‘5.1(side)’
+
FL+FR+FC+LFE+SL+SR
+
+
‘6.0’
+
FL+FR+FC+BC+SL+SR
+
+
‘6.0(front)’
+
FL+FR+FLC+FRC+SL+SR
+
+
‘hexagonal’
+
FL+FR+FC+BL+BR+BC
+
+
‘6.1’
+
FL+FR+FC+LFE+BC+SL+SR
+
+
‘6.1’
+
FL+FR+FC+LFE+BL+BR+BC
+
+
‘6.1(front)’
+
FL+FR+LFE+FLC+FRC+SL+SR
+
+
‘7.0’
+
FL+FR+FC+BL+BR+SL+SR
+
+
‘7.0(front)’
+
FL+FR+FC+FLC+FRC+SL+SR
+
+
‘7.1’
+
FL+FR+FC+LFE+BL+BR+SL+SR
+
+
‘7.1(wide)’
+
FL+FR+FC+LFE+BL+BR+FLC+FRC
+
+
‘7.1(wide-side)’
+
FL+FR+FC+LFE+FLC+FRC+SL+SR
+
+
‘octagonal’
+
FL+FR+FC+BL+BR+BC+SL+SR
+
+
‘downmix’
+
DL+DR
+
+
+
+
A custom channel layout can be specified as a sequence of terms, separated by
+’+’ or ’|’. Each term can be:
+
+
+the name of a standard channel layout (e.g. ‘mono’,
+‘stereo’, ‘4.0’, ‘quad’, ‘5.0’, etc.)
+
+
+the name of a single channel (e.g. ‘FL’, ‘FR’, ‘FC’, ‘LFE’, etc.)
+
+
+a number of channels, in decimal, optionally followed by ’c’, yielding
+the default channel layout for that number of channels (see the
+function av_get_default_channel_layout)
+
+
+a channel layout mask, in hexadecimal starting with "0x" (see the
+AV_CH_* macros in ‘libavutil/channel_layout.h’.
+
+
+
Starting from libavutil version 53 the trailing character "c" to
+specify a number of channels will be required, while a channel layout
+mask could also be specified as a decimal number (if and only if not
+followed by "c").
+
+
See also the function av_get_channel_layout defined in
+‘libavutil/channel_layout.h’.
+
When evaluating an arithmetic expression, FFmpeg uses an internal
+formula evaluator, implemented through the ‘libavutil/eval.h’
+interface.
+
+
An expression may contain unary, binary operators, constants, and
+functions.
+
+
Two expressions expr1 and expr2 can be combined to form
+another expression "expr1;expr2".
+expr1 and expr2 are evaluated in turn, and the new
+expression evaluates to the value of expr2.
+
+
The following binary operators are available: +, -,
+*, /, ^.
+
+
The following unary operators are available: +, -.
+
+
The following functions are available:
+
+
‘abs(x)’
+
Compute absolute value of x.
+
+
+
‘acos(x)’
+
Compute arccosine of x.
+
+
+
‘asin(x)’
+
Compute arcsine of x.
+
+
+
‘atan(x)’
+
Compute arctangent of x.
+
+
+
‘between(x, min, max)’
+
Return 1 if x is greater than or equal to min and lesser than or
+equal to max, 0 otherwise.
+
+
+
‘bitand(x, y)’
+
‘bitor(x, y)’
+
Compute bitwise and/or operation on x and y.
+
+
The results of the evaluation of x and y are converted to
+integers before executing the bitwise operation.
+
+
Note that both the conversion to integer and the conversion back to
+floating point can lose precision. Beware of unexpected results for
+large numbers (usually 2^53 and larger).
+
+
+
‘ceil(expr)’
+
Round the value of expression expr upwards to the nearest
+integer. For example, "ceil(1.5)" is "2.0".
+
+
+
‘cos(x)’
+
Compute cosine of x.
+
+
+
‘cosh(x)’
+
Compute hyperbolic cosine of x.
+
+
+
‘eq(x, y)’
+
Return 1 if x and y are equivalent, 0 otherwise.
+
+
+
‘exp(x)’
+
Compute exponential of x (with base e, the Euler’s number).
+
+
+
‘floor(expr)’
+
Round the value of expression expr downwards to the nearest
+integer. For example, "floor(-1.5)" is "-2.0".
+
+
+
‘gauss(x)’
+
Compute Gauss function of x, corresponding to
+exp(-x*x/2) / sqrt(2*PI).
+
+
+
‘gcd(x, y)’
+
Return the greatest common divisor of x and y. If both x and
+y are 0 or either or both are less than zero then behavior is undefined.
+
+
+
‘gt(x, y)’
+
Return 1 if x is greater than y, 0 otherwise.
+
+
+
‘gte(x, y)’
+
Return 1 if x is greater than or equal to y, 0 otherwise.
+
+
+
‘hypot(x, y)’
+
This function is similar to the C function with the same name; it returns
+"sqrt(x*x + y*y)", the length of the hypotenuse of a
+right triangle with sides of length x and y, or the distance of the
+point (x, y) from the origin.
+
+
+
‘if(x, y)’
+
Evaluate x, and if the result is non-zero return the result of
+the evaluation of y, return 0 otherwise.
+
+
+
‘if(x, y, z)’
+
Evaluate x, and if the result is non-zero return the evaluation
+result of y, otherwise the evaluation result of z.
+
+
+
‘ifnot(x, y)’
+
Evaluate x, and if the result is zero return the result of the
+evaluation of y, return 0 otherwise.
+
+
+
‘ifnot(x, y, z)’
+
Evaluate x, and if the result is zero return the evaluation
+result of y, otherwise the evaluation result of z.
+
+
+
‘isinf(x)’
+
Return 1.0 if x is +/-INFINITY, 0.0 otherwise.
+
+
+
‘isnan(x)’
+
Return 1.0 if x is NAN, 0.0 otherwise.
+
+
+
‘ld(var)’
+
Allow to load the value of the internal variable with number
+var, which was previously stored with st(var, expr).
+The function returns the loaded value.
+
+
+
‘log(x)’
+
Compute natural logarithm of x.
+
+
+
‘lt(x, y)’
+
Return 1 if x is lesser than y, 0 otherwise.
+
+
+
‘lte(x, y)’
+
Return 1 if x is lesser than or equal to y, 0 otherwise.
+
+
+
‘max(x, y)’
+
Return the maximum between x and y.
+
+
+
‘min(x, y)’
+
Return the maximum between x and y.
+
+
+
‘mod(x, y)’
+
Compute the remainder of division of x by y.
+
+
+
‘not(expr)’
+
Return 1.0 if expr is zero, 0.0 otherwise.
+
+
+
‘pow(x, y)’
+
Compute the power of x elevated y, it is equivalent to
+"(x)^(y)".
+
+
+
‘print(t)’
+
‘print(t, l)’
+
Print the value of expression t with loglevel l. If
+l is not specified then a default log level is used.
+Returns the value of the expression printed.
+
+
Prints t with loglevel l
+
+
+
‘random(x)’
+
Return a pseudo random value between 0.0 and 1.0. x is the index of the
+internal variable which will be used to save the seed/state.
+
+
+
‘root(expr, max)’
+
Find an input value for which the function represented by expr
+with argument ld(0) is 0 in the interval 0..max.
+
+
The expression in expr must denote a continuous function or the
+result is undefined.
+
+
ld(0) is used to represent the function input value, which means
+that the given expression will be evaluated multiple times with
+various input values that the expression can access through
+ld(0). When the expression evaluates to 0 then the
+corresponding input value will be returned.
+
+
+
‘sin(x)’
+
Compute sine of x.
+
+
+
‘sinh(x)’
+
Compute hyperbolic sine of x.
+
+
+
‘sqrt(expr)’
+
Compute the square root of expr. This is equivalent to
+"(expr)^.5".
+
+
+
‘squish(x)’
+
Compute expression 1/(1 + exp(4*x)).
+
+
+
‘st(var, expr)’
+
Allow to store the value of the expression expr in an internal
+variable. var specifies the number of the variable where to
+store the value, and it is a value ranging from 0 to 9. The function
+returns the value stored in the internal variable.
+Note, Variables are currently not shared between expressions.
+
+
+
‘tan(x)’
+
Compute tangent of x.
+
+
+
‘tanh(x)’
+
Compute hyperbolic tangent of x.
+
+
+
‘taylor(expr, x)’
+
‘taylor(expr, x, id)’
+
Evaluate a Taylor series at x, given an expression representing
+the ld(id)-th derivative of a function at 0.
+
+
When the series does not converge the result is undefined.
+
+
ld(id) is used to represent the derivative order in expr,
+which means that the given expression will be evaluated multiple times
+with various input values that the expression can access through
+ld(id). If id is not specified then 0 is assumed.
+
+
Note, when you have the derivatives at y instead of 0,
+taylor(expr, x-y) can be used.
+
+
+
‘time(0)’
+
Return the current (wallclock) time in seconds.
+
+
+
‘trunc(expr)’
+
Round the value of expression expr towards zero to the nearest
+integer. For example, "trunc(-1.5)" is "-1.0".
+
+
+
‘while(cond, expr)’
+
Evaluate expression expr while the expression cond is
+non-zero, and returns the value of the last expr evaluation, or
+NAN if cond was always false.
+
+
+
+
The following constants are available:
+
+
‘PI’
+
area of the unit disc, approximately 3.14
+
+
‘E’
+
exp(1) (Euler’s number), approximately 2.718
+
+
‘PHI’
+
golden ratio (1+sqrt(5))/2, approximately 1.618
+
+
+
+
Assuming that an expression is considered "true" if it has a non-zero
+value, note that:
+
+
* works like AND
+
+
+ works like OR
+
+
For example the construct:
+
if (A AND B) then C
+
+
is equivalent to:
+
if(A*B, C)
+
+
+
In your C code, you can extend the list of unary and binary functions,
+and define recognized constants, so that they are available for your
+expressions.
+
+
The evaluator also recognizes the International System unit prefixes.
+If ’i’ is appended after the prefix, binary prefixes are used, which
+are based on powers of 1024 instead of powers of 1000.
+The ’B’ postfix multiplies the value by 8, and can be appended after a
+unit prefix or used alone. This allows using for example ’KB’, ’MiB’,
+’G’ and ’B’ as number postfix.
+
+
The list of available International System prefixes follows, with
+indication of the corresponding powers of 10 and of 2.
+
libavcodec provides some generic global options, which can be set on
+all the encoders and decoders. In addition each codec may support
+so-called private options, which are specific for a given codec.
+
+
Sometimes, a global option may only affect a specific kind of codec,
+and may be unsensical or ignored by another, so you need to be aware
+of the meaning of the specified options. Also some options are
+meant only for decoding or encoding.
+
+
Options may be set by specifying -optionvalue in the
+FFmpeg tools, or by setting the value explicitly in the
+AVCodecContext options or using the ‘libavutil/opt.h’ API
+for programmatic use.
+
+
The list of supported options follow:
+
+
+
‘b integer (encoding,audio,video)’
+
Set bitrate in bits/s. Default value is 200K.
+
+
+
‘ab integer (encoding,audio)’
+
Set audio bitrate (in bits/s). Default value is 128K.
+
+
+
‘bt integer (encoding,video)’
+
Set video bitrate tolerance (in bits/s). In 1-pass mode, bitrate
+tolerance specifies how far ratecontrol is willing to deviate from the
+target average bitrate value. This is not related to min/max
+bitrate. Lowering tolerance too much has an adverse effect on quality.
+
Use internal 2pass ratecontrol in first pass mode.
+
+
‘pass2’
+
Use internal 2pass ratecontrol in second pass mode.
+
+
‘gray’
+
Only decode/encode grayscale.
+
+
‘emu_edge’
+
Do not draw edges.
+
+
‘psnr’
+
Set error[?] variables during encoding.
+
+
‘truncated’
+
‘naq’
+
Normalize adaptive quantization.
+
+
‘ildct’
+
Use interlaced DCT.
+
+
‘low_delay’
+
Force low delay.
+
+
‘global_header’
+
Place global headers in extradata instead of every keyframe.
+
+
‘bitexact’
+
Use only bitexact stuff (except (I)DCT).
+
+
‘aic’
+
Apply H263 advanced intra coding / mpeg4 ac prediction.
+
+
‘cbp’
+
Deprecated, use mpegvideo private options instead.
+
+
‘qprd’
+
Deprecated, use mpegvideo private options instead.
+
+
‘ilme’
+
Apply interlaced motion estimation.
+
+
‘cgop’
+
Use closed gop.
+
+
+
+
+
‘me_method integer (encoding,video)’
+
Set motion estimation method.
+
+
Possible values:
+
+
‘zero’
+
zero motion estimation (fastest)
+
+
‘full’
+
full motion estimation (slowest)
+
+
‘epzs’
+
EPZS motion estimation (default)
+
+
‘esa’
+
esa motion estimation (alias for full)
+
+
‘tesa’
+
tesa motion estimation
+
+
‘dia’
+
dia motion estimation (alias for epzs)
+
+
‘log’
+
log motion estimation
+
+
‘phods’
+
phods motion estimation
+
+
‘x1’
+
X1 motion estimation
+
+
‘hex’
+
hex motion estimation
+
+
‘umh’
+
umh motion estimation
+
+
‘iter’
+
iter motion estimation
+
+
+
+
+
‘extradata_size integer’
+
Set extradata size.
+
+
+
‘time_base rational number’
+
Set codec time base.
+
+
It is the fundamental unit of time (in seconds) in terms of which
+frame timestamps are represented. For fixed-fps content, timebase
+should be 1 / frame_rate and timestamp increments should be
+identically 1.
+
+
+
‘g integer (encoding,video)’
+
Set the group of picture size. Default value is 12.
+
+
+
‘ar integer (decoding/encoding,audio)’
+
Set audio sampling rate (in Hz).
+
+
+
‘ac integer (decoding/encoding,audio)’
+
Set number of audio channels.
+
+
+
‘cutoff integer (encoding,audio)’
+
Set cutoff bandwidth.
+
+
+
‘frame_size integer (encoding,audio)’
+
Set audio frame size.
+
+
Each submitted frame except the last must contain exactly frame_size
+samples per channel. May be 0 when the codec has
+CODEC_CAP_VARIABLE_FRAME_SIZE set, in that case the frame size is not
+restricted. It is set by some decoders to indicate constant frame
+size.
+
+
+
‘frame_number integer’
+
Set the frame number.
+
+
+
‘delay integer’
+
‘qcomp float (encoding,video)’
+
Set video quantizer scale compression (VBR). It is used as a constant
+in the ratecontrol equation. Recommended range for default rc_eq:
+0.0-1.0.
+
+
+
‘qblur float (encoding,video)’
+
Set video quantizer scale blur (VBR).
+
+
+
‘qmin integer (encoding,video)’
+
Set min video quantizer scale (VBR). Must be included between -1 and
+69, default value is 2.
+
+
+
‘qmax integer (encoding,video)’
+
Set max video quantizer scale (VBR). Must be included between -1 and
+1024, default value is 31.
+
+
+
‘qdiff integer (encoding,video)’
+
Set max difference between the quantizer scale (VBR).
+
+
+
‘bf integer (encoding,video)’
+
Set max number of B frames.
+
+
+
‘b_qfactor float (encoding,video)’
+
Set qp factor between P and B frames.
+
+
+
‘rc_strategy integer (encoding,video)’
+
Set ratecontrol method.
+
+
+
‘b_strategy integer (encoding,video)’
+
Set strategy to choose between I/P/B-frames.
+
+
+
‘ps integer (encoding,video)’
+
Set RTP payload size in bytes.
+
+
+
‘mv_bits integer’
+
‘header_bits integer’
+
‘i_tex_bits integer’
+
‘p_tex_bits integer’
+
‘i_count integer’
+
‘p_count integer’
+
‘skip_count integer’
+
‘misc_bits integer’
+
‘frame_bits integer’
+
‘codec_tag integer’
+
‘bug flags (decoding,video)’
+
Workaround not auto detected encoder bugs.
+
+
Possible values:
+
+
‘autodetect’
+
‘old_msmpeg4’
+
some old lavc generated msmpeg4v3 files (no autodetection)
+
+
‘xvid_ilace’
+
Xvid interlacing bug (autodetected if fourcc==XVIX)
+
+
‘ump4’
+
(autodetected if fourcc==UMP4)
+
+
‘no_padding’
+
padding bug (autodetected)
+
+
‘amv’
+
‘ac_vlc’
+
illegal vlc bug (autodetected per fourcc)
+
+
‘qpel_chroma’
+
‘std_qpel’
+
old standard qpel (autodetected per fourcc/version)
+
+
‘qpel_chroma2’
+
‘direct_blocksize’
+
direct-qpel-blocksize bug (autodetected per fourcc/version)
+
+
‘edge’
+
edge padding bug (autodetected per fourcc/version)
+
+
‘hpel_chroma’
+
‘dc_clip’
+
‘ms’
+
Workaround various bugs in microsoft broken decoders.
+
+
‘trunc’
+
trancated frames
+
+
+
+
+
‘lelim integer (encoding,video)’
+
Set single coefficient elimination threshold for luminance (negative
+values also consider DC coefficient).
+
+
+
‘celim integer (encoding,video)’
+
Set single coefficient elimination threshold for chrominance (negative
+values also consider dc coefficient)
+
+
+
‘strict integer (decoding/encoding,audio,video)’
+
Specify how strictly to follow the standards.
+
+
Possible values:
+
+
‘very’
+
strictly conform to a older more strict version of the spec or reference software
+
+
‘strict’
+
strictly conform to all the things in the spec no matter what consequences
+
+
‘normal’
+
‘unofficial’
+
allow unofficial extensions
+
+
‘experimental’
+
allow non standardized experimental things, experimental
+(unfinished/work in progress/not well tested) decoders and encoders.
+Note: experimental decoders can pose a security risk, do not use this for
+decoding untrusted input.
+
+
+
+
+
‘b_qoffset float (encoding,video)’
+
Set QP offset between P and B frames.
+
+
+
‘err_detect flags (decoding,audio,video)’
+
Set error detection flags.
+
+
Possible values:
+
+
‘crccheck’
+
verify embedded CRCs
+
+
‘bitstream’
+
detect bitstream specification deviations
+
+
‘buffer’
+
detect improper bitstream length
+
+
‘explode’
+
abort decoding on minor error detection
+
+
‘careful’
+
consider things that violate the spec and have not been seen in the wild as errors
+
+
‘compliant’
+
consider all spec non compliancies as errors
+
+
‘aggressive’
+
consider things that a sane encoder should not do as an error
+
+
+
+
+
‘has_b_frames integer’
+
‘block_align integer’
+
‘mpeg_quant integer (encoding,video)’
+
Use MPEG quantizers instead of H.263.
+
+
+
‘qsquish float (encoding,video)’
+
How to keep quantizer between qmin and qmax (0 = clip, 1 = use
+differentiable function).
+
+
+
‘rc_qmod_amp float (encoding,video)’
+
Set experimental quantizer modulation.
+
+
+
‘rc_qmod_freq integer (encoding,video)’
+
Set experimental quantizer modulation.
+
+
+
‘rc_override_count integer’
+
‘rc_eq string (encoding,video)’
+
Set rate control equation. When computing the expression, besides the
+standard functions defined in the section ’Expression Evaluation’, the
+following functions are available: bits2qp(bits), qp2bits(qp). Also
+the following constants are available: iTex pTex tex mv fCode iCount
+mcVar var isI isP isB avgQP qComp avgIITex avgPITex avgPPTex avgBPTex
+avgTex.
+
+
+
‘maxrate integer (encoding,audio,video)’
+
Set max bitrate tolerance (in bits/s). Requires bufsize to be set.
+
+
+
‘minrate integer (encoding,audio,video)’
+
Set min bitrate tolerance (in bits/s). Most useful in setting up a CBR
+encode. It is of little use elsewise.
+
+
+
‘bufsize integer (encoding,audio,video)’
+
Set ratecontrol buffer size (in bits).
+
+
+
‘rc_buf_aggressivity float (encoding,video)’
+
Currently useless.
+
+
+
‘i_qfactor float (encoding,video)’
+
Set QP factor between P and I frames.
+
+
+
‘i_qoffset float (encoding,video)’
+
Set QP offset between P and I frames.
+
+
+
‘rc_init_cplx float (encoding,video)’
+
Set initial complexity for 1-pass encoding.
+
+
+
‘dct integer (encoding,video)’
+
Set DCT algorithm.
+
+
Possible values:
+
+
‘auto’
+
autoselect a good one (default)
+
+
‘fastint’
+
fast integer
+
+
‘int’
+
accurate integer
+
+
‘mmx’
+
‘altivec’
+
‘faan’
+
floating point AAN DCT
+
+
+
+
+
‘lumi_mask float (encoding,video)’
+
Compress bright areas stronger than medium ones.
+
Number of slices, used in parallelized encoding.
+
+
+
‘thread_type flags (decoding/encoding,video)’
+
Select multithreading type.
+
+
Possible values:
+
+
‘slice’
+
‘frame’
+
+
+
‘audio_service_type integer (encoding,audio)’
+
Set audio service type.
+
+
Possible values:
+
+
‘ma’
+
Main Audio Service
+
+
‘ef’
+
Effects
+
+
‘vi’
+
Visually Impaired
+
+
‘hi’
+
Hearing Impaired
+
+
‘di’
+
Dialogue
+
+
‘co’
+
Commentary
+
+
‘em’
+
Emergency
+
+
‘vo’
+
Voice Over
+
+
‘ka’
+
Karaoke
+
+
+
+
+
‘request_sample_fmt sample_fmt (decoding,audio)’
+
Set sample format audio decoders should prefer. Default value is
+none.
+
+
+
‘pkt_timebase rational number’
+
‘sub_charenc encoding (decoding,subtitles)’
+
Set the input subtitles character encoding.
+
+
+
‘field_order field_order (video)’
+
Set/override the field order of the video.
+Possible values:
+
+
‘progressive’
+
Progressive video
+
+
‘tt’
+
Interlaced video, top field coded and displayed first
+
+
‘bb’
+
Interlaced video, bottom field coded and displayed first
+
+
‘tb’
+
Interlaced video, top coded first, bottom displayed first
+
+
‘bt’
+
Interlaced video, bottom coded first, top displayed first
+
+
+
+
+
‘skip_alpha integer (decoding,video)’
+
Set to 1 to disable processing alpha (transparency). This works like the
+‘gray’ flag in the ‘flags’ option which skips chroma information
+instead of alpha. Default is 0.
+
Decoders are configured elements in FFmpeg which allow the decoding of
+multimedia streams.
+
+
When you configure your FFmpeg build, all the supported native decoders
+are enabled by default. Decoders requiring an external library must be enabled
+manually via the corresponding --enable-lib option. You can list all
+available decoders using the configure option --list-decoders.
+
+
You can disable all the decoders with the configure option
+--disable-decoders and selectively enable / disable single decoders
+with the options --enable-decoder=DECODER /
+--disable-decoder=DECODER.
+
+
The option -codecs of the ff* tools will display the list of
+enabled decoders.
+
This decoder generates wave patterns according to predefined sequences. Its
+use is purely internal and the format of the data it accepts is not publicly
+documented.
+
libcelt allows libavcodec to decode the Xiph CELT ultra-low delay audio codec.
+Requires the presence of the libcelt headers and library during configuration.
+You need to explicitly configure the build with --enable-libcelt.
+
libgsm allows libavcodec to decode the GSM full rate audio codec. Requires
+the presence of the libgsm headers and library during configuration. You need
+to explicitly configure the build with --enable-libgsm.
+
+
This decoder supports both the ordinary GSM and the Microsoft variant.
+
libilbc allows libavcodec to decode the Internet Low Bitrate Codec (iLBC)
+audio codec. Requires the presence of the libilbc headers and library during
+configuration. You need to explicitly configure the build with
+--enable-libilbc.
+
libopencore-amrnb allows libavcodec to decode the Adaptive Multi-Rate
+Narrowband audio codec. Using it requires the presence of the
+libopencore-amrnb headers and library during configuration. You need to
+explicitly configure the build with --enable-libopencore-amrnb.
+
+
An FFmpeg native decoder for AMR-NB exists, so users can decode AMR-NB
+without this library.
+
libopencore-amrwb allows libavcodec to decode the Adaptive Multi-Rate
+Wideband audio codec. Using it requires the presence of the
+libopencore-amrwb headers and library during configuration. You need to
+explicitly configure the build with --enable-libopencore-amrwb.
+
+
An FFmpeg native decoder for AMR-WB exists, so users can decode AMR-WB
+without this library.
+
libopus allows libavcodec to decode the Opus Interactive Audio Codec.
+Requires the presence of the libopus headers and library during
+configuration. You need to explicitly configure the build with
+--enable-libopus.
+
Specify the global palette used by the bitmaps. When stored in VobSub, the
+palette is normally specified in the index file; in Matroska, the palette is
+stored in the codec extra-data in the same format as in VobSub. In DVDs, the
+palette is stored in the IFO file, and therefore not available when reading
+from dumped VOB files.
+
+
The format for this option is a string containing 16 24-bits hexadecimal
+numbers (without 0x prefix) separated by comas, for example 0d00ee,
+ee450d, 101010, eaeaea, 0ce60b, ec14ed, ebff0b, 0d617a, 7b7b7b, d1d1d1,
+7b2a0e, 0d950c, 0f007b, cf0dec, cfa80c, 7c127b.
+
Libzvbi allows libavcodec to decode DVB teletext pages and DVB teletext
+subtitles. Requires the presence of the libzvbi headers and library during
+configuration. You need to explicitly configure the build with
+--enable-libzvbi.
+
List of teletext page numbers to decode. You may use the special * string to
+match all pages. Pages that do not match the specified list are dropped.
+Default value is *.
+
+
‘txt_chop_top’
+
Discards the top teletext line. Default value is 1.
+
+
‘txt_format’
+
Specifies the format of the decoded subtitles. The teletext decoder is capable
+of decoding the teletext pages to bitmaps or to simple text, you should use
+"bitmap" for teletext pages, because certain graphics and colors cannot be
+expressed in simple text. You might use "text" for teletext based subtitles if
+your application can handle simple text based subtitles. Default value is
+bitmap.
+
+
‘txt_left’
+
X offset of generated bitmaps, default is 0.
+
+
‘txt_top’
+
Y offset of generated bitmaps, default is 0.
+
+
‘txt_chop_spaces’
+
Chops leading and trailing spaces and removes empty lines from the generated
+text. This option is useful for teletext based subtitles where empty spaces may
+be present at the start or at the end of the lines or empty lines may be
+present between the subtitle lines because of double-sized teletext charactes.
+Default value is 1.
+
+
‘txt_duration’
+
Sets the display duration of the decoded teletext pages or subtitles in
+miliseconds. Default value is 30000 which is 30 seconds.
+
+
‘txt_transparent’
+
Force transparent background of the generated teletext bitmaps. Default value
+is 0 which means an opaque (black) background.
+
Encoders are configured elements in FFmpeg which allow the encoding of
+multimedia streams.
+
+
When you configure your FFmpeg build, all the supported native encoders
+are enabled by default. Encoders requiring an external library must be enabled
+manually via the corresponding --enable-lib option. You can list all
+available encoders using the configure option --list-encoders.
+
+
You can disable all the encoders with the configure option
+--disable-encoders and selectively enable / disable single encoders
+with the options --enable-encoder=ENCODER /
+--disable-encoder=ENCODER.
+
+
The option -codecs of the ff* tools will display the list of
+enabled encoders.
+
This encoder is an experimental FFmpeg-native AAC encoder. Currently only the
+low complexity (AAC-LC) profile is supported. To use this encoder, you must set
+‘strict’ option to ‘experimental’ or lower.
+
+
As this encoder is experimental, unexpected behavior may exist from time to
+time. For a more stable AAC encoder, see libvo-aacenc. However, be warned
+that it has a worse quality reported by some users.
+
Set bit rate in bits/s. Setting this automatically activates constant bit rate
+(CBR) mode.
+
+
+
‘q’
+
Set quality for variable bit rate (VBR) mode. This option is valid only using
+the ffmpeg command-line tool. For library interface users, use
+‘global_quality’.
+
+
+
‘stereo_mode’
+
Set stereo encoding mode. Possible values:
+
+
+
‘auto’
+
Automatically selected by the encoder.
+
+
+
‘ms_off’
+
Disable middle/side encoding. This is the default.
+
+
+
‘ms_force’
+
Force middle/side encoding.
+
+
+
+
+
‘aac_coder’
+
Set AAC encoder coding method. Possible values:
+
+
+
‘faac’
+
FAAC-inspired method.
+
+
This method is a simplified reimplementation of the method used in FAAC, which
+sets thresholds proportional to the band energies, and then decreases all the
+thresholds with quantizer steps to find the appropriate quantization with
+distortion below threshold band by band.
+
+
The quality of this method is comparable to the two loop searching method
+descibed below, but somewhat a little better and slower.
+
+
+
‘anmr’
+
Average noise to mask ratio (ANMR) trellis-based solution.
+
+
This has a theoretic best quality out of all the coding methods, but at the
+cost of the slowest speed.
+
+
+
‘twoloop’
+
Two loop searching (TLS) method.
+
+
This method first sets quantizers depending on band thresholds and then tries
+to find an optimal combination by adding or subtracting a specific value from
+all quantizers and adjusting some individual quantizer a little.
+
+
This method produces similar quality with the FAAC method and is the default.
+
+
+
‘fast’
+
Constant quantizer method.
+
+
This method sets a constant quantizer for all bands. This is the fastest of all
+the methods, yet produces the worst quality.
+
These encoders implement part of ATSC A/52:2010 and ETSI TS 102 366, as well as
+the undocumented RealAudio 3 (a.k.a. dnet).
+
+
The ac3 encoder uses floating-point math, while the ac3_fixed
+encoder only uses fixed-point integer math. This does not mean that one is
+always faster, just that one or the other may be better suited to a
+particular system. The floating-point encoder will generally produce better
+quality audio for a given bitrate. The ac3_fixed encoder is not the
+default codec for any of the output formats, so it must be specified explicitly
+using the option -acodec ac3_fixed in order to use it.
+
The AC-3 metadata options are used to set parameters that describe the audio,
+but in most cases do not affect the audio encoding itself. Some of the options
+do directly affect or influence the decoding and playback of the resulting
+bitstream, while others are just for informational purposes. A few of the
+options will add bits to the output stream that could otherwise be used for
+audio data, and will thus affect the quality of the output. Those will be
+indicated accordingly with a note in the option list below.
+
+
These parameters are described in detail in several publicly-available
+documents.
+
Center Mix Level. The amount of gain the decoder should apply to the center
+channel when downmixing to stereo. This field will only be written to the
+bitstream if a center channel is present. The value is specified as a scale
+factor. There are 3 valid values:
+
+
‘0.707’
+
Apply -3dB gain
+
+
‘0.595’
+
Apply -4.5dB gain (default)
+
+
‘0.500’
+
Apply -6dB gain
+
+
+
+
+
‘-surround_mixlev level’
+
Surround Mix Level. The amount of gain the decoder should apply to the surround
+channel(s) when downmixing to stereo. This field will only be written to the
+bitstream if one or more surround channels are present. The value is specified
+as a scale factor. There are 3 valid values:
+
Audio Production Information is optional information describing the mixing
+environment. Either none or both of the fields are written to the bitstream.
+
+
+
‘-mixing_level number’
+
Mixing Level. Specifies peak sound pressure level (SPL) in the production
+environment when the mix was mastered. Valid values are 80 to 111, or -1 for
+unknown or not indicated. The default value is -1, but that value cannot be
+used if the Audio Production Information is written to the bitstream. Therefore,
+if the room_type option is not the default value, the mixing_level
+option must not be -1.
+
+
+
‘-room_type type’
+
Room Type. Describes the equalization used during the final mixing session at
+the studio or on the dubbing stage. A large room is a dubbing stage with the
+industry standard X-curve equalization; a small room has flat equalization.
+This field will not be written to the bitstream if both the mixing_level
+option and the room_type option have the default values.
+
Copyright Indicator. Specifies whether a copyright exists for this audio.
+
+
‘0’
+
‘off’
+
No Copyright Exists (default)
+
+
‘1’
+
‘on’
+
Copyright Exists
+
+
+
+
+
‘-dialnorm value’
+
Dialogue Normalization. Indicates how far the average dialogue level of the
+program is below digital 100% full scale (0 dBFS). This parameter determines a
+level shift during audio reproduction that sets the average volume of the
+dialogue to a preset level. The goal is to match volume level between program
+sources. A value of -31dB will result in no volume level change, relative to
+the source volume, during audio reproduction. Valid values are whole numbers in
+the range -31 to -1, with -31 being the default.
+
+
+
‘-dsur_mode mode’
+
Dolby Surround Mode. Specifies whether the stereo signal uses Dolby Surround
+(Pro Logic). This field will only be written to the bitstream if the audio
+stream is stereo. Using this option does NOT mean the encoder will actually
+apply Dolby Surround processing.
+
+
‘0’
+
‘notindicated’
+
Not Indicated (default)
+
+
‘1’
+
‘off’
+
Not Dolby Surround Encoded
+
+
‘2’
+
‘on’
+
Dolby Surround Encoded
+
+
+
+
+
‘-original boolean’
+
Original Bit Stream Indicator. Specifies whether this audio is from the
+original source and not a copy.
+
The extended bitstream options are part of the Alternate Bit Stream Syntax as
+specified in Annex D of the A/52:2010 standard. It is grouped into 2 parts.
+If any one parameter in a group is specified, all values in that group will be
+written to the bitstream. Default values are used for those that are written
+but have not been specified. If the mixing levels are written, the decoder
+will use these values instead of the ones specified in the center_mixlev
+and surround_mixlev options if it supports the Alternate Bit Stream
+Syntax.
+
Preferred Stereo Downmix Mode. Allows the user to select either Lt/Rt
+(Dolby Surround) or Lo/Ro (normal stereo) as the preferred stereo downmix mode.
+
+
‘0’
+
‘notindicated’
+
Not Indicated (default)
+
+
‘1’
+
‘ltrt’
+
Lt/Rt Downmix Preferred
+
+
‘2’
+
‘loro’
+
Lo/Ro Downmix Preferred
+
+
+
+
+
‘-ltrt_cmixlev level’
+
Lt/Rt Center Mix Level. The amount of gain the decoder should apply to the
+center channel when downmixing to stereo in Lt/Rt mode.
+
+
‘1.414’
+
Apply +3dB gain
+
+
‘1.189’
+
Apply +1.5dB gain
+
+
‘1.000’
+
Apply 0dB gain
+
+
‘0.841’
+
Apply -1.5dB gain
+
+
‘0.707’
+
Apply -3.0dB gain
+
+
‘0.595’
+
Apply -4.5dB gain (default)
+
+
‘0.500’
+
Apply -6.0dB gain
+
+
‘0.000’
+
Silence Center Channel
+
+
+
+
+
‘-ltrt_surmixlev level’
+
Lt/Rt Surround Mix Level. The amount of gain the decoder should apply to the
+surround channel(s) when downmixing to stereo in Lt/Rt mode.
+
+
‘0.841’
+
Apply -1.5dB gain
+
+
‘0.707’
+
Apply -3.0dB gain
+
+
‘0.595’
+
Apply -4.5dB gain
+
+
‘0.500’
+
Apply -6.0dB gain (default)
+
+
‘0.000’
+
Silence Surround Channel(s)
+
+
+
+
+
‘-loro_cmixlev level’
+
Lo/Ro Center Mix Level. The amount of gain the decoder should apply to the
+center channel when downmixing to stereo in Lo/Ro mode.
+
+
‘1.414’
+
Apply +3dB gain
+
+
‘1.189’
+
Apply +1.5dB gain
+
+
‘1.000’
+
Apply 0dB gain
+
+
‘0.841’
+
Apply -1.5dB gain
+
+
‘0.707’
+
Apply -3.0dB gain
+
+
‘0.595’
+
Apply -4.5dB gain (default)
+
+
‘0.500’
+
Apply -6.0dB gain
+
+
‘0.000’
+
Silence Center Channel
+
+
+
+
+
‘-loro_surmixlev level’
+
Lo/Ro Surround Mix Level. The amount of gain the decoder should apply to the
+surround channel(s) when downmixing to stereo in Lo/Ro mode.
+
Dolby Surround EX Mode. Indicates whether the stream uses Dolby Surround EX
+(7.1 matrixed to 5.1). Using this option does NOT mean the encoder will actually
+apply Dolby Surround EX processing.
+
+
‘0’
+
‘notindicated’
+
Not Indicated (default)
+
+
‘1’
+
‘on’
+
Dolby Surround EX Off
+
+
‘2’
+
‘off’
+
Dolby Surround EX On
+
+
+
+
+
‘-dheadphone_mode mode’
+
Dolby Headphone Mode. Indicates whether the stream uses Dolby Headphone
+encoding (multi-channel matrixed to 2.0 for use with headphones). Using this
+option does NOT mean the encoder will actually apply Dolby Headphone
+processing.
+
+
‘0’
+
‘notindicated’
+
Not Indicated (default)
+
+
‘1’
+
‘on’
+
Dolby Headphone Off
+
+
‘2’
+
‘off’
+
Dolby Headphone On
+
+
+
+
+
‘-ad_conv_type type’
+
A/D Converter Type. Indicates whether the audio has passed through HDCD A/D
+conversion.
+
Stereo Rematrixing. Enables/Disables use of rematrixing for stereo input. This
+is an optional AC-3 feature that increases quality by selectively encoding
+the left/right channels as mid/side. This option is enabled by default, and it
+is highly recommended that it be left as enabled except for testing purposes.
+
These options are only valid for the floating-point encoder and do not exist
+for the fixed-point encoder due to the corresponding features not being
+implemented in fixed-point.
+
+
+
‘-channel_coupling boolean’
+
Enables/Disables use of channel coupling, which is an optional AC-3 feature
+that increases quality by combining high frequency information from multiple
+channels into a single channel. The per-channel high frequency information is
+sent with less accuracy in both the frequency and time domains. This allows
+more bits to be used for lower frequencies while preserving enough information
+to reconstruct the high frequencies. This option is enabled by default for the
+floating-point encoder and should generally be left as enabled except for
+testing purposes or to increase encoding speed.
+
+
‘-1’
+
‘auto’
+
Selected by Encoder (default)
+
+
‘0’
+
‘off’
+
Disable Channel Coupling
+
+
‘1’
+
‘on’
+
Enable Channel Coupling
+
+
+
+
+
‘-cpl_start_band number’
+
Coupling Start Band. Sets the channel coupling start band, from 1 to 15. If a
+value higher than the bandwidth is used, it will be reduced to 1 less than the
+coupling end band. If auto is used, the start band will be determined by
+the encoder based on the bit rate, sample rate, and channel layout. This option
+has no effect if channel coupling is disabled.
+
LAME (Lame Ain’t an MP3 Encoder) MP3 encoder wrapper.
+
+
Requires the presence of the libmp3lame headers and library during
+configuration. You need to explicitly configure the build with
+--enable-libmp3lame.
+
+
See libshine for a fixed-point MP3 encoder, although with a
+lower quality.
+
The following options are supported by the libmp3lame wrapper. The
+lame-equivalent of the options are listed in parentheses.
+
+
+
‘b (-b)’
+
Set bitrate expressed in bits/s for CBR. LAME bitrate is
+expressed in kilobits/s.
+
+
+
‘q (-V)’
+
Set constant quality setting for VBR. This option is valid only
+using the ffmpeg command-line tool. For library interface
+users, use ‘global_quality’.
+
+
+
‘compression_level (-q)’
+
Set algorithm quality. Valid arguments are integers in the 0-9 range,
+with 0 meaning highest quality but slowest, and 9 meaning fastest
+while producing the worst quality.
+
+
+
‘reservoir’
+
Enable use of bit reservoir when set to 1. Default value is 1. LAME
+has this enabled by default, but can be overriden by use
+‘--nores’ option.
+
+
+
‘joint_stereo (-m j)’
+
Enable the encoder to use (on a frame by frame basis) either L/R
+stereo or mid/side stereo. Default value is 1.
+
Requires the presence of the libopencore-amrnb headers and library during
+configuration. You need to explicitly configure the build with
+--enable-libopencore-amrnb --enable-version3.
+
+
This is a mono-only encoder. Officially it only supports 8000Hz sample rate,
+but you can override it by setting ‘strict’ to ‘unofficial’ or
+lower.
+
Shine is a fixed-point MP3 encoder. It has a far better performance on
+platforms without an FPU, e.g. armel CPUs, and some phones and tablets.
+However, as it is more targeted on performance than quality, it is not on par
+with LAME and other production-grade encoders quality-wise. Also, according to
+the project’s homepage, this encoder may not be free of bugs as the code was
+written a long time ago and the project was dead for at least 5 years.
+
+
This encoder only supports stereo and mono input. This is also CBR-only.
+
Requires the presence of the libtwolame headers and library during
+configuration. You need to explicitly configure the build with
+--enable-libtwolame.
+
The following options are supported by the libtwolame wrapper. The
+twolame-equivalent options follow the FFmpeg ones and are in
+parentheses.
+
+
+
‘b (-b)’
+
Set bitrate expressed in bits/s for CBR. twolame ‘b’
+option is expressed in kilobits/s. Default value is 128k.
+
+
+
‘q (-V)’
+
Set quality for experimental VBR support. Maximum value range is
+from -50 to 50, useful range is from -10 to 10. The higher the
+value, the better the quality. This option is valid only using the
+ffmpeg command-line tool. For library interface users,
+use ‘global_quality’.
+
+
+
‘mode (--mode)’
+
Set the mode of the resulting audio. Possible values:
+
+
+
‘auto’
+
Choose mode automatically based on the input. This is the default.
+
+
‘stereo’
+
Stereo
+
+
‘joint_stereo’
+
Joint stereo
+
+
‘dual_channel’
+
Dual channel
+
+
‘mono’
+
Mono
+
+
+
+
+
‘psymodel (--psyc-mode)’
+
Set psychoacoustic model to use in encoding. The argument must be
+an integer between -1 and 4, inclusive. The higher the value, the
+better the quality. The default value is 3.
+
+
+
‘energy_levels (--energy)’
+
Enable energy levels extensions when set to 1. The default value is
+0 (disabled).
+
+
+
‘error_protection (--protect)’
+
Enable CRC error protection when set to 1. The default value is 0
+(disabled).
+
+
+
‘copyright (--copyright)’
+
Set MPEG audio copyright flag when set to 1. The default value is 0
+(disabled).
+
+
+
‘original (--original)’
+
Set MPEG audio original flag when set to 1. The default value is 0
+(disabled).
+
Requires the presence of the libvo-aacenc headers and library during
+configuration. You need to explicitly configure the build with
+--enable-libvo-aacenc --enable-version3.
+
Requires the presence of the libvo-amrwbenc headers and library during
+configuration. You need to explicitly configure the build with
+--enable-libvo-amrwbenc --enable-version3.
+
+
This is a mono-only encoder. Officially it only supports 16000Hz sample
+rate, but you can override it by setting ‘strict’ to
+‘unofficial’ or lower.
+
Most libopus options are modeled after the opusenc utility from
+opus-tools. The following is an option mapping chart describing options
+supported by the libopus wrapper, and their opusenc-equivalent
+in parentheses.
+
+
+
‘b (bitrate)’
+
Set the bit rate in bits/s. FFmpeg’s ‘b’ option is
+expressed in bits/s, while opusenc’s ‘bitrate’ in
+kilobits/s.
+
+
+
‘vbr (vbr, hard-cbr, and cvbr)’
+
Set VBR mode. The FFmpeg ‘vbr’ option has the following
+valid arguments, with the their opusenc equivalent options
+in parentheses:
+
+
+
‘off (hard-cbr)’
+
Use constant bit rate encoding.
+
+
+
‘on (vbr)’
+
Use variable bit rate encoding (the default).
+
+
+
‘constrained (cvbr)’
+
Use constrained variable bit rate encoding.
+
+
+
+
+
‘compression_level (comp)’
+
Set encoding algorithm complexity. Valid options are integers in
+the 0-10 range. 0 gives the fastest encodes but lower quality, while 10
+gives the highest quality but slowest encoding. The default is 10.
+
+
+
‘frame_duration (framesize)’
+
Set maximum frame size, or duration of a frame in milliseconds. The
+argument must be exactly the following: 2.5, 5, 10, 20, 40, 60. Smaller
+frame sizes achieve lower latency but less quality at a given bitrate.
+Sizes greater than 20ms are only interesting at fairly low bitrates.
+The default is 20ms.
+
+
+
‘packet_loss (expect-loss)’
+
Set expected packet loss percentage. The default is 0.
+
+
+
‘application (N.A.)’
+
Set intended application type. Valid options are listed below:
+
+
+
‘voip’
+
Favor improved speech intelligibility.
+
+
‘audio’
+
Favor faithfulness to the input (the default).
+
+
‘lowdelay’
+
Restrict to only the lowest delay modes.
+
+
+
+
+
‘cutoff (N.A.)’
+
Set cutoff bandwidth in Hz. The argument must be exactly one of the
+following: 4000, 6000, 8000, 12000, or 20000, corresponding to
+narrowband, mediumband, wideband, super wideband, and fullband
+respectively. The default is 0 (cutoff disabled).
+
Requires the presence of the libvorbisenc headers and library during
+configuration. You need to explicitly configure the build with
+--enable-libvorbis.
+
Set bitrate expressed in bits/s for ABR. oggenc ‘-b’ is
+expressed in kilobits/s.
+
+
+
‘q (-q)’
+
Set constant quality setting for VBR. The value should be a float
+number in the range of -1.0 to 10.0. The higher the value, the better
+the quality. The default value is ‘3.0’.
+
+
This option is valid only using the ffmpeg command-line tool.
+For library interface users, use ‘global_quality’.
+
Set noise floor bias for impulse blocks. The value is a float number from
+-15.0 to 0.0. A negative bias instructs the encoder to pay special attention
+to the crispness of transients in the encoded audio. The tradeoff for better
+transient response is a higher bitrate.
+
A wrapper providing WavPack encoding through libwavpack.
+
+
Only lossless mode using 32-bit integer samples is supported currently.
+The ‘compression_level’ option can be used to control speed vs.
+compression tradeoff, with the values mapped to libwavpack as follows:
+
+
+
‘0’
+
Fast mode - corresponding to the wavpack ‘-f’ option.
+
+
+
‘1’
+
Normal (default) settings.
+
+
+
‘2’
+
High quality - corresponding to the wavpack ‘-h’ option.
+
+
+
‘3’
+
Very high quality - corresponding to the wavpack ‘-hh’ option.
+
+
+
‘4-8’
+
Same as 3, but with extra processing enabled - corresponding to the wavpack
+‘-x’ option. I.e. 4 is the same as ‘-x2’ and 8 is the same as
+‘-x6’.
+
Requires the presence of the libtheora headers and library during
+configuration. You need to explicitly configure the build with
+--enable-libtheora.
+
The following global options are mapped to internal libtheora options
+which affect the quality and the bitrate of the encoded stream.
+
+
+
‘b’
+
Set the video bitrate, only works if the qscale flag in
+‘flags’ is not enabled.
+
+
+
‘flags’
+
Used to enable constant quality mode encoding through the
+‘qscale’ flag, and to enable the pass1 and pass2
+modes.
+
+
+
‘g’
+
Set the GOP size.
+
+
+
‘global_quality’
+
Set the global quality in lambda units, only works if the
+qscale flag in ‘flags’ is enabled. The value is clipped
+in the [0 - 10*FF_QP2LAMBDA] range, and then multiplied for 6.3
+to get a value in the native libtheora range [0-63]. A higher value
+corresponds to a higher quality.
+
+
For example, to set maximum constant quality encoding with
+ffmpeg:
+
This encoder requires the presence of the libx264 headers and library
+during configuration. You need to explicitly configure the build with
+--enable-libx264.
+
+
libx264 supports an impressive number of features, including 8x8 and
+4x4 adaptive spatial transform, adaptive B-frame placement, CAVLC/CABAC
+entropy coding, interlacing (MBAFF), lossless mode, psy optimizations
+for detail retention (adaptive quantization, psy-RD, psy-trellis).
+
+
Many libx264 encoder options are mapped to FFmpeg global codec
+options, while unique encoder options are provided through private
+options. Additionally the ‘x264opts’ and ‘x264-params’
+private options allows to pass a list of key=value tuples as accepted
+by the libx264 x264_param_parse function.
+
The following options are supported by the libx264 wrapper. The
+x264-equivalent options or values are listed in parentheses
+for easy migration.
+
+
To reduce the duplication of documentation, only the private options
+and some others requiring special attention are documented here. For
+the documentation of the undocumented generic options, see
+the Codec Options chapter.
+
+
To get a more accurate and extensive documentation of the libx264
+options, invoke the command x264 --full-help or consult
+the libx264 documentation.
+
+
+
‘b (bitrate)’
+
Set bitrate in bits/s. Note that FFmpeg’s ‘b’ option is
+expressed in bits/s, while x264’s ‘bitrate’ is in
+kilobits/s.
+
+
+
‘bf (bframes)’
+
‘g (keyint)’
+
‘qmax (qpmax)’
+
‘qmin (qpmin)’
+
‘qdiff (qpstep)’
+
‘qblur (qblur)’
+
‘qcomp (qcomp)’
+
‘refs (ref)’
+
‘sc_threshold (scenecut)’
+
‘trellis (trellis)’
+
‘nr (nr)’
+
‘me_range (merange)’
+
‘me_method (me)’
+
Set motion estimation method. Possible values in the decreasing order
+of speed:
+
+
+
‘dia (dia)’
+
‘epzs (dia)’
+
Diamond search with radius 1 (fastest). ‘epzs’ is an alias for
+‘dia’.
+
+
‘hex (hex)’
+
Hexagonal search with radius 2.
+
+
‘umh (umh)’
+
Uneven multi-hexagon search.
+
+
‘esa (esa)’
+
Exhaustive search.
+
+
‘tesa (tesa)’
+
Hadamard exhaustive search (slowest).
+
+
+
+
+
‘subq (subme)’
+
‘b_strategy (b-adapt)’
+
‘keyint_min (min-keyint)’
+
‘coder’
+
Set entropy encoder. Possible values:
+
+
+
‘ac’
+
Enable CABAC.
+
+
+
‘vlc’
+
Enable CAVLC and disable CABAC. It generates the same effect as
+x264’s ‘--no-cabac’ option.
+
+
+
+
+
‘cmp’
+
Set full pixel motion estimation comparation algorithm. Possible values:
+
+
+
‘chroma’
+
Enable chroma in motion estimation.
+
+
+
‘sad’
+
Ignore chroma in motion estimation. It generates the same effect as
+x264’s ‘--no-chroma-me’ option.
+
+
+
+
+
‘threads (threads)’
+
‘thread_type’
+
Set multithreading technique. Possible values:
+
+
+
‘slice’
+
Slice-based multithreading. It generates the same effect as
+x264’s ‘--sliced-threads’ option.
+
+
‘frame’
+
Frame-based multithreading.
+
+
+
+
+
‘flags’
+
Set encoding flags. It can be used to disable closed GOP and enable
+open GOP by setting it to -cgop. The result is similar to
+the behavior of x264’s ‘--open-gop’ option.
+
+
+
‘rc_init_occupancy (vbv-init)’
+
‘preset (preset)’
+
Set the encoding preset.
+
+
+
‘tune (tune)’
+
Set tuning of the encoding params.
+
+
+
‘profile (profile)’
+
Set profile restrictions.
+
+
+
‘fastfirstpass’
+
Enable fast settings when encoding first pass, when set to 1. When set
+to 0, it has the same effect of x264’s
+‘--slow-firstpass’ option.
+
+
+
‘crf (crf)’
+
Set the quality for constant quality mode.
+
+
+
‘crf_max (crf-max)’
+
In CRF mode, prevents VBV from lowering quality beyond this point.
+
+
+
‘qp (qp)’
+
Set constant quantization rate control method parameter.
+
+
+
‘aq-mode (aq-mode)’
+
Set AQ method. Possible values:
+
+
+
‘none (0)’
+
Disabled.
+
+
+
‘variance (1)’
+
Variance AQ (complexity mask).
+
+
+
‘autovariance (2)’
+
Auto-variance AQ (experimental).
+
+
+
+
+
‘aq-strength (aq-strength)’
+
Set AQ strength, reduce blocking and blurring in flat and textured areas.
+
+
+
‘psy’
+
Use psychovisual optimizations when set to 1. When set to 0, it has the
+same effect as x264’s ‘--no-psy’ option.
+
+
+
‘psy-rd (psy-rd)’
+
Set strength of psychovisual optimization, in
+psy-rd:psy-trellis format.
+
+
+
‘rc-lookahead (rc-lookahead)’
+
Set number of frames to look ahead for frametype and ratecontrol.
+
+
+
‘weightb’
+
Enable weighted prediction for B-frames when set to 1. When set to 0,
+it has the same effect as x264’s ‘--no-weightb’ option.
+
+
+
‘weightp (weightp)’
+
Set weighted prediction method for P-frames. Possible values:
+
+
+
‘none (0)’
+
Disabled
+
+
‘simple (1)’
+
Enable only weighted refs
+
+
‘smart (2)’
+
Enable both weighted refs and duplicates
+
+
+
+
+
‘ssim (ssim)’
+
Enable calculation and printing SSIM stats after the encoding.
+
+
+
‘intra-refresh (intra-refresh)’
+
Enable the use of Periodic Intra Refresh instead of IDR frames when set
+to 1.
+
+
+
‘bluray-compat (bluray-compat)’
+
Configure the encoder to be compatible with the bluray standard.
+It is a shorthand for setting "bluray-compat=1 force-cfr=1".
+
+
+
‘b-bias (b-bias)’
+
Set the influence on how often B-frames are used.
+
+
+
‘b-pyramid (b-pyramid)’
+
Set method for keeping of some B-frames as references. Possible values:
+
+
+
‘none (none)’
+
Disabled.
+
+
‘strict (strict)’
+
Strictly hierarchical pyramid.
+
+
‘normal (normal)’
+
Non-strict (not Blu-ray compatible).
+
+
+
+
+
‘mixed-refs’
+
Enable the use of one reference per partition, as opposed to one
+reference per macroblock when set to 1. When set to 0, it has the
+same effect as x264’s ‘--no-mixed-refs’ option.
+
+
+
‘8x8dct’
+
Enable adaptive spatial transform (high profile 8x8 transform)
+when set to 1. When set to 0, it has the same effect as
+x264’s ‘--no-8x8dct’ option.
+
+
+
‘fast-pskip’
+
Enable early SKIP detection on P-frames when set to 1. When set
+to 0, it has the same effect as x264’s
+‘--no-fast-pskip’ option.
+
+
+
‘aud (aud)’
+
Enable use of access unit delimiters when set to 1.
+
+
+
‘mbtree’
+
Enable use macroblock tree ratecontrol when set to 1. When set
+to 0, it has the same effect as x264’s
+‘--no-mbtree’ option.
+
+
+
‘deblock (deblock)’
+
Set loop filter parameters, in alpha:beta form.
+
+
+
‘cplxblur (cplxblur)’
+
Set fluctuations reduction in QP (before curve compression).
+
+
+
‘partitions (partitions)’
+
Set partitions to consider as a comma-separated list of. Possible
+values in the list:
+
+
+
‘p8x8’
+
8x8 P-frame partition.
+
+
‘p4x4’
+
4x4 P-frame partition.
+
+
‘b8x8’
+
4x4 B-frame partition.
+
+
‘i8x8’
+
8x8 I-frame partition.
+
+
‘i4x4’
+
4x4 I-frame partition.
+(Enabling ‘p4x4’ requires ‘p8x8’ to be enabled. Enabling
+‘i8x8’ requires adaptive spatial transform (‘8x8dct’
+option) to be enabled.)
+
+
‘none (none)’
+
Do not consider any partitions.
+
+
‘all (all)’
+
Consider every partition.
+
+
+
+
+
‘direct-pred (direct)’
+
Set direct MV prediction mode. Possible values:
+
+
+
‘none (none)’
+
Disable MV prediction.
+
+
‘spatial (spatial)’
+
Enable spatial predicting.
+
+
‘temporal (temporal)’
+
Enable temporal predicting.
+
+
‘auto (auto)’
+
Automatically decided.
+
+
+
+
+
‘slice-max-size (slice-max-size)’
+
Set the limit of the size of each slice in bytes. If not specified
+but RTP payload size (‘ps’) is specified, that is used.
+
+
+
‘stats (stats)’
+
Set the file name for multi-pass stats.
+
+
+
‘nal-hrd (nal-hrd)’
+
Set signal HRD information (requires ‘vbv-bufsize’ to be set).
+Possible values:
+
+
+
‘none (none)’
+
Disable HRD information signaling.
+
+
‘vbr (vbr)’
+
Variable bit rate.
+
+
‘cbr (cbr)’
+
Constant bit rate (not allowed in MP4 container).
+
+
+
+
+
‘x264opts (N.A.)’
+
Set any x264 option, see x264 --fullhelp for a list.
+
+
Argument is a list of key=value couples separated by
+":". In filter and psy-rd options that use ":" as a separator
+themselves, use "," instead. They accept it as well since long ago but this
+is kept undocumented for some reason.
+
+
For example to specify libx264 encoding options with ffmpeg:
+
This encoder requires the presence of the libxvidcore headers and library
+during configuration. You need to explicitly configure the build with
+--enable-libxvid --enable-gpl.
+
+
The native mpeg4 encoder supports the MPEG-4 Part 2 format, so
+users can encode to this format without this library.
+
The following options are supported by the libxvid wrapper. Some of
+the following options are listed but are not documented, and
+correspond to shared codec options. See the Codec Options chapter for their documentation. The other shared options
+which are not listed have no effect for the libxvid encoder.
+
+
+
‘b’
+
‘g’
+
‘qmin’
+
‘qmax’
+
‘mpeg_quant’
+
‘threads’
+
‘bf’
+
‘b_qfactor’
+
‘b_qoffset’
+
‘flags’
+
Set specific encoding flags. Possible values:
+
+
+
‘mv4’
+
Use four motion vector by macroblock.
+
+
+
‘aic’
+
Enable high quality AC prediction.
+
+
+
‘gray’
+
Only encode grayscale.
+
+
+
‘gmc’
+
Enable the use of global motion compensation (GMC).
+
+
+
‘qpel’
+
Enable quarter-pixel motion compensation.
+
+
+
‘cgop’
+
Enable closed GOP.
+
+
+
‘global_header’
+
Place global headers in extradata instead of every keyframe.
+
+
+
+
+
+
‘trellis’
+
‘me_method’
+
Set motion estimation method. Possible values in decreasing order of
+speed and increasing order of quality:
+
+
+
‘zero’
+
Use no motion estimation (default).
+
+
+
‘phods’
+
‘x1’
+
‘log’
+
Enable advanced diamond zonal search for 16x16 blocks and half-pixel
+refinement for 16x16 blocks. ‘x1’ and ‘log’ are aliases for
+‘phods’.
+
+
+
‘epzs’
+
Enable all of the things described above, plus advanced diamond zonal
+search for 8x8 blocks, half-pixel refinement for 8x8 blocks, and motion
+estimation on chroma planes.
+
+
+
‘full’
+
Enable all of the things described above, plus extended 16x16 and 8x8
+blocks search.
+
+
+
+
+
‘mbd’
+
Set macroblock decision algorithm. Possible values in the increasing
+order of quality:
+
+
+
‘simple’
+
Use macroblock comparing function algorithm (default).
+
+
+
‘bits’
+
Enable rate distortion-based half pixel and quarter pixel refinement for
+16x16 blocks.
+
+
+
‘rd’
+
Enable all of the things described above, plus rate distortion-based
+half pixel and quarter pixel refinement for 8x8 blocks, and rate
+distortion-based search using square pattern.
+
+
+
+
+
‘lumi_aq’
+
Enable lumi masking adaptive quantization when set to 1. Default is 0
+(disabled).
+
+
+
‘variance_aq’
+
Enable variance adaptive quantization when set to 1. Default is 0
+(disabled).
+
+
When combined with ‘lumi_aq’, the resulting quality will not
+be better than any of the two specified individually. In other
+words, the resulting quality will be the worse one of the two
+effects.
+
+
+
‘ssim’
+
Set structural similarity (SSIM) displaying method. Possible values:
+
+
+
‘off’
+
Disable displaying of SSIM information.
+
+
+
‘avg’
+
Output average SSIM at the end of encoding to stdout. The format of
+showing the average SSIM is:
+
+
Average SSIM: %f
+
+
+
For users who are not familiar with C, %f means a float number, or
+a decimal (e.g. 0.939232).
+
+
+
‘frame’
+
Output both per-frame SSIM data during encoding and average SSIM at
+the end of encoding to stdout. The format of per-frame information
+is:
+
+
SSIM: avg: %1.3f min: %1.3f max: %1.3f
+
+
+
For users who are not familiar with C, %1.3f means a float number
+rounded to 3 digits after the dot (e.g. 0.932).
+
+
+
+
+
+
‘ssim_acc’
+
Set SSIM accuracy. Valid options are integers within the range of
+0-4, while 0 gives the most accurate result and 4 computes the
+fastest.
+
In the default mode of operation the encoder has to honor frame constraints
+(i.e. not produc frames with size bigger than requested) while still making
+output picture as good as possible.
+A frame containing a lot of small details is harder to compress and the encoder
+would spend more time searching for appropriate quantizers for each slice.
+
+
Setting a higher ‘bits_per_mb’ limit will improve the speed.
+
+
For the fastest encoding speed set the ‘qscale’ parameter (4 is the
+recommended value) and do not set a size constraint.
+
When you configure your FFmpeg build, all the supported bitstream
+filters are enabled by default. You can list all available ones using
+the configure option --list-bsfs.
+
+
You can disable all the bitstream filters using the configure option
+--disable-bsfs, and selectively enable any bitstream filter using
+the option --enable-bsf=BSF, or you can disable a particular
+bitstream filter using the option --disable-bsf=BSF.
+
+
The option -bsfs of the ff* tools will display the list of
+all the supported bitstream filters included in your build.
+
+
Below is a description of the currently available bitstream filters.
+
Add extradata to the beginning of the filtered packets.
+
+
The additional argument specifies which packets should be filtered.
+It accepts the values:
+
+
‘a’
+
add extradata to all key packets, but only if local_header is
+set in the ‘flags2’ codec context field
+
+
+
‘k’
+
add extradata to all key packets
+
+
+
‘e’
+
add extradata to all packets
+
+
+
+
If not specified it is assumed ‘k’.
+
+
For example the following ffmpeg command forces a global
+header (thus disabling individual packet headers) in the H.264 packets
+generated by the libx264 encoder, but corrects them by adding
+the header stored in extradata to the key packets:
+
Avery Lee, writing in the rec.video.desktop newsgroup in 2001,
+commented that "MJPEG, or at least the MJPEG in AVIs having the
+MJPG fourcc, is restricted JPEG with a fixed – and *omitted* –
+Huffman table. The JPEG must be YCbCr colorspace, it must be 4:2:2,
+and it must use basic Huffman encoding, not arithmetic or
+progressive. . . . You can indeed extract the MJPEG frames and
+decode them with a regular JPEG decoder, but you have to prepend
+the DHT segment to them, or else the decoder won’t have any idea
+how to decompress the data. The exact table necessary is given in
+the OpenDML spec."
+
+
This bitstream filter patches the header of frames extracted from an MJPEG
+stream (carrying the AVI1 header ID and lacking a DHT segment) to
+produce fully qualified JPEG images.
+
The libavformat library provides some generic global options, which
+can be set on all the muxers and demuxers. In addition each muxer or
+demuxer may support so-called private options, which are specific for
+that component.
+
+
Options may be set by specifying -optionvalue in the
+FFmpeg tools, or by setting the value explicitly in the
+AVFormatContext options or using the ‘libavutil/opt.h’ API
+for programmatic use.
+
+
The list of supported options follows:
+
+
+
‘avioflags flags (input/output)’
+
Possible values:
+
+
‘direct’
+
Reduce buffering.
+
+
+
+
+
‘probesize integer (input)’
+
Set probing size in bytes, i.e. the size of the data to analyze to get
+stream information. A higher value will allow to detect more
+information in case it is dispersed into the stream, but will increase
+latency. Must be an integer not lesser than 32. It is 5000000 by default.
+
+
+
‘packetsize integer (output)’
+
Set packet size.
+
+
+
‘fflags flags (input/output)’
+
Set format flags.
+
+
Possible values:
+
+
‘ignidx’
+
Ignore index.
+
+
‘genpts’
+
Generate PTS.
+
+
‘nofillin’
+
Do not fill in missing values that can be exactly calculated.
+
+
‘noparse’
+
Disable AVParsers, this needs +nofillin too.
+
+
‘igndts’
+
Ignore DTS.
+
+
‘discardcorrupt’
+
Discard corrupted frames.
+
+
‘sortdts’
+
Try to interleave output packets by DTS.
+
+
‘keepside’
+
Do not merge side data.
+
+
‘latm’
+
Enable RTP MP4A-LATM payload.
+
+
‘nobuffer’
+
Reduce the latency introduced by optional buffering
+
+
+
+
+
‘seek2any integer (input)’
+
Allow seeking to non-keyframes on demuxer level when supported if set to 1.
+Default is 0.
+
+
+
‘analyzeduration integer (input)’
+
Specify how many microseconds are analyzed to probe the input. A
+higher value will allow to detect more accurate information, but will
+increase latency. It defaults to 5,000,000 microseconds = 5 seconds.
+
+
+
‘cryptokey hexadecimal string (input)’
+
Set decryption key.
+
+
+
‘indexmem integer (input)’
+
Set max memory used for timestamp index (per stream).
+
+
+
‘rtbufsize integer (input)’
+
Set max memory used for buffering real-time frames.
+
+
+
‘fdebug flags (input/output)’
+
Print specific debug info.
+
+
Possible values:
+
+
‘ts’
+
+
+
+
‘max_delay integer (input/output)’
+
Set maximum muxing or demuxing delay in microseconds.
+
+
+
‘fpsprobesize integer (input)’
+
Set number of frames used to probe fps.
+
+
+
‘audio_preload integer (output)’
+
Set microseconds by which audio packets should be interleaved earlier.
+
+
+
‘chunk_duration integer (output)’
+
Set microseconds for each chunk.
+
+
+
‘chunk_size integer (output)’
+
Set size in bytes for each chunk.
+
+
+
‘err_detect, f_err_detect flags (input)’
+
Set error detection flags. f_err_detect is deprecated and
+should be used only via the ffmpeg tool.
+
+
Possible values:
+
+
‘crccheck’
+
Verify embedded CRCs.
+
+
‘bitstream’
+
Detect bitstream specification deviations.
+
+
‘buffer’
+
Detect improper bitstream length.
+
+
‘explode’
+
Abort decoding on minor error detection.
+
+
‘careful’
+
Consider things that violate the spec and have not been seen in the
+wild as errors.
+
+
‘compliant’
+
Consider all spec non compliancies as errors.
+
+
‘aggressive’
+
Consider things that a sane encoder should not do as an error.
+
+
+
+
+
‘use_wallclock_as_timestamps integer (input)’
+
Use wallclock as timestamps.
+
+
+
‘avoid_negative_ts integer (output)’
+
Shift timestamps to make them non-negative. A value of 1 enables shifting,
+a value of 0 disables it, the default value of -1 enables shifting
+when required by the target format.
+
+
When shifting is enabled, all output timestamps are shifted by the
+same amount. Audio, video, and subtitles desynching and relative
+timestamp differences are preserved compared to how they would have
+been without shifting.
+
+
Also note that this affects only leading negative timestamps, and not
+non-monotonic negative timestamps.
+
+
+
‘skip_initial_bytes integer (input)’
+
Set number of bytes to skip before reading header and frames if set to 1.
+Default is 0.
+
+
+
‘correct_ts_overflow integer (input)’
+
Correct single timestamp overflows if set to 1. Default is 1.
+
+
+
‘flush_packets integer (output)’
+
Flush the underlying I/O stream after each packet. Default 1 enables it, and
+has the effect of reducing the latency; 0 disables it and may slightly
+increase performance in some cases.
+
Format stream specifiers allow selection of one or more streams that
+match specific properties.
+
+
Possible forms of stream specifiers are:
+
+
‘stream_index’
+
Matches the stream with this index.
+
+
+
‘stream_type[:stream_index]’
+
stream_type is one of following: ’v’ for video, ’a’ for audio,
+’s’ for subtitle, ’d’ for data, and ’t’ for attachments. If
+stream_index is given, then it matches the stream number
+stream_index of this type. Otherwise, it matches all streams of
+this type.
+
+
+
‘p:program_id[:stream_index]’
+
If stream_index is given, then it matches the stream with number
+stream_index in the program with the id
+program_id. Otherwise, it matches all streams in the program.
+
+
+
‘#stream_id’
+
Matches the stream by a format-specific ID.
+
+
+
+
The exact semantics of stream specifiers is defined by the
+avformat_match_stream_specifier() function declared in the
+‘libavformat/avformat.h’ header.
+
Demuxers are configured elements in FFmpeg that can read the
+multimedia streams from a particular type of file.
+
+
When you configure your FFmpeg build, all the supported demuxers
+are enabled by default. You can list all available ones using the
+configure option --list-demuxers.
+
+
You can disable all the demuxers using the configure option
+--disable-demuxers, and selectively enable a single demuxer with
+the option --enable-demuxer=DEMUXER, or disable it
+with the option --disable-demuxer=DEMUXER.
+
+
The option -formats of the ff* tools will display the list of
+enabled demuxers.
+
+
The description of some of the currently available demuxers follows.
+
This demuxer presents all AVStreams from all variant streams.
+The id field is set to the bitrate variant index number. By setting
+the discard flags on AVStreams (by pressing ’a’ or ’v’ in ffplay),
+the caller can decide which variant streams to actually receive.
+The total bitrate of the variant that the stream belongs to is
+available in a metadata key named "variant_bitrate".
+
This demuxer reads a list of files and other directives from a text file and
+demuxes them one after the other, as if all their packet had been muxed
+together.
+
+
The timestamps in the files are adjusted so that the first file starts at 0
+and each next file starts where the previous one finishes. Note that it is
+done globally and may cause gaps if all streams do not have exactly the same
+length.
+
+
All files must have the same streams (same codecs, same time base, etc.).
+
+
The duration of each file is used to adjust the timestamps of the next file:
+if the duration is incorrect (because it was computed using the bit-rate or
+because the file is truncated, for example), it can cause artifacts. The
+duration directive can be used to override the duration stored in
+each file.
+
The script is a text file in extended-ASCII, with one directive per line.
+Empty lines, leading spaces and lines starting with ’#’ are ignored. The
+following directive is recognized:
+
+
+
‘file path’
+
Path to a file to read; special characters and spaces must be escaped with
+backslash or single quotes.
+
+
All subsequent directives apply to that file.
+
+
+
‘ffconcat version 1.0’
+
Identify the script type and version. It also sets the ‘safe’ option
+to 1 if it was to its default -1.
+
+
To make FFmpeg recognize the format automatically, this directive must
+appears exactly as is (no extra space or byte-order-mark) on the very first
+line of the script.
+
+
+
‘duration dur’
+
Duration of the file. This information can be specified from the file;
+specifying it here may be more efficient or help if the information from the
+file is not available or accurate.
+
+
If the duration is set for all files, then it is possible to seek in the
+whole concatenated video.
+
If set to 1, reject unsafe file paths. A file path is considered safe if it
+does not contain a protocol specification and is relative and all components
+only contain characters from the portable character set (letters, digits,
+period, underscore and hyphen) and have no period at the beginning of a
+component.
+
+
If set to 0, any file name is accepted.
+
+
The default is -1, it is equivalent to 1 if the format was automatically
+probed and 0 otherwise.
+
Some files have multiple tracks. The demuxer will pick the first track by
+default. The ‘track_index’ option can be used to select a different
+track. Track indexes start at 0. The demuxer exports the number of tracks as
+tracks meta data entry.
+
+
For very large files, the ‘max_size’ option may have to be adjusted.
+
This demuxer reads from a list of image files specified by a pattern.
+The syntax and meaning of the pattern is specified by the
+option pattern_type.
+
+
The pattern may contain a suffix which is used to automatically
+determine the format of the images contained in the files.
+
+
The size, the pixel format, and the format of each image must be the
+same for all the files in the sequence.
+
+
This demuxer accepts the following options:
+
+
‘framerate’
+
Set the frame rate for the video stream. It defaults to 25.
+
+
‘loop’
+
If set to 1, loop over the input. Default value is 0.
+
+
‘pattern_type’
+
Select the pattern type used to interpret the provided filename.
+
+
pattern_type accepts one of the following values.
+
+
‘sequence’
+
Select a sequence pattern type, used to specify a sequence of files
+indexed by sequential numbers.
+
+
A sequence pattern may contain the string "%d" or "%0Nd", which
+specifies the position of the characters representing a sequential
+number in each filename matched by the pattern. If the form
+"%d0Nd" is used, the string representing the number in each
+filename is 0-padded and N is the total number of 0-padded
+digits representing the number. The literal character ’%’ can be
+specified in the pattern with the string "%%".
+
+
If the sequence pattern contains "%d" or "%0Nd", the first filename of
+the file list specified by the pattern must contain a number
+inclusively contained between start_number and
+start_number+start_number_range-1, and all the following
+numbers must be sequential.
+
+
For example the pattern "img-%03d.bmp" will match a sequence of
+filenames of the form ‘img-001.bmp’, ‘img-002.bmp’, ...,
+‘img-010.bmp’, etc.; the pattern "i%%m%%g-%d.jpg" will match a
+sequence of filenames of the form ‘i%m%g-1.jpg’,
+‘i%m%g-2.jpg’, ..., ‘i%m%g-10.jpg’, etc.
+
+
Note that the pattern must not necessarily contain "%d" or
+"%0Nd", for example to convert a single image file
+‘img.jpeg’ you can employ the command:
+
ffmpeg -i img.jpeg img.png
+
+
+
+
‘glob’
+
Select a glob wildcard pattern type.
+
+
The pattern is interpreted like a glob() pattern. This is only
+selectable if libavformat was compiled with globbing support.
+
+
+
‘glob_sequence (deprecated, will be removed)’
+
Select a mixed glob wildcard/sequence pattern.
+
+
If your version of libavformat was compiled with globbing support, and
+the provided pattern contains at least one glob meta character among
+%*?[]{} that is preceded by an unescaped "%", the pattern is
+interpreted like a glob() pattern, otherwise it is interpreted
+like a sequence pattern.
+
+
All glob special characters %*?[]{} must be prefixed
+with "%". To escape a literal "%" you shall use "%%".
+
+
For example the pattern foo-%*.jpeg will match all the
+filenames prefixed by "foo-" and terminating with ".jpeg", and
+foo-%?%?%?.jpeg will match all the filenames prefixed with
+"foo-", followed by a sequence of three characters, and terminating
+with ".jpeg".
+
+
This pattern type is deprecated in favor of glob and
+sequence.
+
+
+
+
Default value is glob_sequence.
+
+
‘pixel_format’
+
Set the pixel format of the images to read. If not specified the pixel
+format is guessed from the first image file in the sequence.
+
+
‘start_number’
+
Set the index of the file matched by the image file pattern to start
+to read from. Default value is 0.
+
+
‘start_number_range’
+
Set the index interval range to check when looking for the first image
+file in the sequence, starting from start_number. Default value
+is 5.
+
+
‘ts_from_file’
+
If set to 1, will set frame timestamp to modification time of image file. Note
+that monotonity of timestamps is not provided: images go in the same order as
+without this option. Default value is 0.
+
+
‘video_size’
+
Set the video size of the images to read. If not specified the video
+size is guessed from the first image file in the sequence.
+
+Use ffmpeg for creating a video from the images in the file
+sequence ‘img-001.jpeg’, ‘img-002.jpeg’, ..., assuming an
+input frame rate of 10 frames per second:
+
ffmpeg -framerate 10 -i 'img-%03d.jpeg' out.mkv
+
+
+
+As above, but start by reading from a file with index 100 in the sequence:
+
Overrides teletext packet PTS and DTS values with the timestamps calculated
+from the PCR of the first program which the teletext stream is part of and is
+not discarded. Default value is 1, set this option to 0 if you want your
+teletext packet PTS and DTS values untouched.
+
This demuxer allows to read raw video data. Since there is no header
+specifying the assumed video parameters, the user must specify them
+in order to be able to decode the data correctly.
+
+
This demuxer accepts the following options:
+
+
‘framerate’
+
Set input video frame rate. Default value is 25.
+
+
+
‘pixel_format’
+
Set the input video pixel format. Default value is yuv420p.
+
+
+
‘video_size’
+
Set the input video size. This value must be specified explicitly.
+
+
+
+
For example to read a rawvideo file ‘input.raw’ with
+ffplay, assuming a pixel format of rgb24, a video
+size of 320x240, and a frame rate of 10 images per second, use
+the command:
+
This demuxer reads the script language used by SBaGen
+http://uazu.net/sbagen/ to generate binaural beats sessions. A SBG
+script looks like that:
+
-SE
+a: 300-2.5/3 440+4.5/0
+b: 300-2.5/0 440+4.5/3
+off: -
+NOW == a
++0:07:00 == b
++0:14:00 == a
++0:21:00 == b
++0:30:00 off
+
+
+
A SBG script can mix absolute and relative timestamps. If the script uses
+either only absolute timestamps (including the script start time) or only
+relative ones, then its layout is fixed, and the conversion is
+straightforward. On the other hand, if the script mixes both kind of
+timestamps, then the NOW reference for relative timestamps will be
+taken from the current time of day at the time the script is read, and the
+script layout will be frozen according to that reference. That means that if
+the script is directly played, the actual times will match the absolute
+timestamps up to the sound controller’s clock accuracy, but if the user
+somehow pauses the playback or seeks, all times will be shifted accordingly.
+
TED does not provide links to the captions, but they can be guessed from the
+page. The file ‘tools/bookmarklets.html’ from the FFmpeg source tree
+contains a bookmarklet to expose them.
+
+
This demuxer accepts the following option:
+
+
‘start_time’
+
Set the start time of the TED talk, in milliseconds. The default is 15000
+(15s). It is used to sync the captions with the downloadable videos, because
+they include a 15s intro.
+
+
+
+
Example: convert the captions to a format most players understand:
+
Muxers are configured elements in FFmpeg which allow writing
+multimedia streams to a particular type of file.
+
+
When you configure your FFmpeg build, all the supported muxers
+are enabled by default. You can list all available muxers using the
+configure option --list-muxers.
+
+
You can disable all the muxers with the configure option
+--disable-muxers and selectively enable / disable single muxers
+with the options --enable-muxer=MUXER /
+--disable-muxer=MUXER.
+
+
The option -formats of the ff* tools will display the list of
+enabled muxers.
+
+
A description of some of the currently available muxers follows.
+
This muxer computes and prints the Adler-32 CRC of all the input audio
+and video frames. By default audio frames are converted to signed
+16-bit raw audio and video frames to raw video before computing the
+CRC.
+
+
The output of the muxer consists of a single line of the form:
+CRC=0xCRC, where CRC is a hexadecimal number 0-padded to
+8 digits containing the CRC for all the decoded input frames.
+
+
For example to compute the CRC of the input, and store it in the file
+‘out.crc’:
+
ffmpeg -i INPUT -f crc out.crc
+
+
+
You can print the CRC to stdout with the command:
+
ffmpeg -i INPUT -f crc -
+
+
+
You can select the output format of each frame with ffmpeg by
+specifying the audio and video codec and format. For example to
+compute the CRC of the input audio converted to PCM unsigned 8-bit
+and the input video converted to MPEG-2 video, use the command:
+
This muxer computes and prints the Adler-32 CRC for each audio
+and video packet. By default audio frames are converted to signed
+16-bit raw audio and video frames to raw video before computing the
+CRC.
+
+
The output of the muxer consists of a line for each audio and video
+packet of the form:
+
CRC is a hexadecimal number 0-padded to 8 digits containing the
+CRC of the packet.
+
+
For example to compute the CRC of the audio and video frames in
+‘INPUT’, converted to raw audio and video packets, and store it
+in the file ‘out.crc’:
+
ffmpeg -i INPUT -f framecrc out.crc
+
+
+
To print the information to stdout, use the command:
+
ffmpeg -i INPUT -f framecrc -
+
+
+
With ffmpeg, you can select the output format to which the
+audio and video frames are encoded before computing the CRC for each
+packet by specifying the audio and video codec. For example, to
+compute the CRC of each decoded input audio frame converted to PCM
+unsigned 8-bit and of each decoded input video frame converted to
+MPEG-2 video, use the command:
+
This muxer computes and prints the MD5 hash for each audio
+and video packet. By default audio frames are converted to signed
+16-bit raw audio and video frames to raw video before computing the
+hash.
+
+
The output of the muxer consists of a line for each audio and video
+packet of the form:
+
MD5 is a hexadecimal number representing the computed MD5 hash
+for the packet.
+
+
For example to compute the MD5 of the audio and video frames in
+‘INPUT’, converted to raw audio and video packets, and store it
+in the file ‘out.md5’:
+
ffmpeg -i INPUT -f framemd5 out.md5
+
+
+
To print the information to stdout, use the command:
+
Apple HTTP Live Streaming muxer that segments MPEG-TS according to
+the HTTP Live Streaming specification.
+
+
It creates a playlist file and numbered segment files. The output
+filename specifies the playlist filename; the segment filenames
+receive the same basename as the playlist, a sequential number and
+a .ts extension.
+
The image file muxer writes video frames to image files.
+
+
The output filenames are specified by a pattern, which can be used to
+produce sequentially numbered series of files.
+The pattern may contain the string "%d" or "%0Nd", this string
+specifies the position of the characters representing a numbering in
+the filenames. If the form "%0Nd" is used, the string
+representing the number in each filename is 0-padded to N
+digits. The literal character ’%’ can be specified in the pattern with
+the string "%%".
+
+
If the pattern contains "%d" or "%0Nd", the first filename of
+the file list specified will contain the number 1, all the following
+numbers will be sequential.
+
+
The pattern may contain a suffix which is used to automatically
+determine the format of the image files to write.
+
+
For example the pattern "img-%03d.bmp" will specify a sequence of
+filenames of the form ‘img-001.bmp’, ‘img-002.bmp’, ...,
+‘img-010.bmp’, etc.
+The pattern "img%%-%d.jpg" will specify a sequence of filenames of the
+form ‘img%-1.jpg’, ‘img%-2.jpg’, ..., ‘img%-10.jpg’,
+etc.
+
+
The following example shows how to use ffmpeg for creating a
+sequence of files ‘img-001.jpeg’, ‘img-002.jpeg’, ...,
+taking one image every second from the input video:
+
Note that with ffmpeg, if the format is not specified with the
+-f option and the output filename specifies an image file
+format, the image2 muxer is automatically selected, so the previous
+command can be written as:
+
ffmpeg -i in.avi -vsync 1 -r 1 'img-%03d.jpeg'
+
+
+
Note also that the pattern must not necessarily contain "%d" or
+"%0Nd", for example to create a single image file
+‘img.jpeg’ from the input video you can employ the command:
+
ffmpeg -i in.avi -f image2 -frames:v 1 img.jpeg
+
+
+
+
‘start_number number’
+
Start the sequence from number. Default value is 1. Must be a
+non-negative number.
+
+
+
‘-update number’
+
If number is nonzero, the filename will always be interpreted as just a
+filename, not a pattern, and this file will be continuously overwritten with new
+images.
+
+
+
+
+
The image muxer supports the .Y.U.V image file format. This format is
+special in that that each image frame consists of three files, for
+each of the YUV420P components. To read or write this image file format,
+specify the name of the ’.Y’ file. The muxer will automatically open the
+’.U’ and ’.V’ files as required.
+
By default, this muxer writes the index for seeking (called cues in Matroska
+terms) at the end of the file, because it cannot know in advance how much space
+to leave for the index at the beginning of the file. However for some use cases
+– e.g. streaming where seeking is possible but slow – it is useful to put the
+index at the beginning of the file.
+
+
If this option is set to a non-zero value, the muxer will reserve a given amount
+of space in the file header and then try to write the cues there when the muxing
+finishes. If the available space does not suffice, muxing will fail. A safe size
+for most use cases should be about 50kB per hour of video.
+
+
Note that cues are only written if the output is seekable and this option will
+have no effect if it is not.
+
This muxer computes and prints the MD5 hash of all the input audio
+and video frames. By default audio frames are converted to signed
+16-bit raw audio and video frames to raw video before computing the
+hash.
+
+
The output of the muxer consists of a single line of the form:
+MD5=MD5, where MD5 is a hexadecimal number representing
+the computed MD5 hash.
+
+
For example to compute the MD5 hash of the input converted to raw
+audio and video, and store it in the file ‘out.md5’:
+
ffmpeg -i INPUT -f md5 out.md5
+
+
+
You can print the MD5 to stdout with the command:
+
The mov/mp4/ismv muxer supports fragmentation. Normally, a MOV/MP4
+file has all the metadata about all packets stored in one location
+(written at the end of the file, it can be moved to the start for
+better playback by adding faststart to the movflags, or
+using the qt-faststart tool). A fragmented
+file consists of a number of fragments, where packets and metadata
+about these packets are stored together. Writing a fragmented
+file has the advantage that the file is decodable even if the
+writing is interrupted (while a normal MOV/MP4 is undecodable if
+it is not properly finished), and it requires less memory when writing
+very long files (since writing normal MOV/MP4 files stores info about
+every single packet in memory until the file is closed). The downside
+is that it is less compatible with other applications.
+
+
Fragmentation is enabled by setting one of the AVOptions that define
+how to cut the file into fragments:
+
+
+
‘-moov_size bytes’
+
Reserves space for the moov atom at the beginning of the file instead of placing the
+moov atom at the end. If the space reserved is insufficient, muxing will fail.
+
+
‘-movflags frag_keyframe’
+
Start a new fragment at each video keyframe.
+
+
‘-frag_duration duration’
+
Create fragments that are duration microseconds long.
+
+
‘-frag_size size’
+
Create fragments that contain up to size bytes of payload data.
+
+
‘-movflags frag_custom’
+
Allow the caller to manually choose when to cut fragments, by
+calling av_write_frame(ctx, NULL) to write a fragment with
+the packets written so far. (This is only useful with other
+applications integrating libavformat, not from ffmpeg.)
+
+
‘-min_frag_duration duration’
+
Don’t create fragments that are shorter than duration microseconds long.
+
+
+
+
If more than one condition is specified, fragments are cut when
+one of the specified conditions is fulfilled. The exception to this is
+-min_frag_duration, which has to be fulfilled for any of the other
+conditions to apply.
+
+
Additionally, the way the output file is written can be adjusted
+through a few other options:
+
+
+
‘-movflags empty_moov’
+
Write an initial moov atom directly at the start of the file, without
+describing any samples in it. Generally, an mdat/moov pair is written
+at the start of the file, as a normal MOV/MP4 file, containing only
+a short portion of the file. With this option set, there is no initial
+mdat atom, and the moov atom only describes the tracks but has
+a zero duration.
+
+
Files written with this option set do not work in QuickTime.
+This option is implicitly set when writing ismv (Smooth Streaming) files.
+
+
‘-movflags separate_moof’
+
Write a separate moof (movie fragment) atom for each track. Normally,
+packets for all tracks are written in a moof atom (which is slightly
+more efficient), but with this option set, the muxer writes one moof/mdat
+pair for each track, making it easier to separate tracks.
+
+
This option is implicitly set when writing ismv (Smooth Streaming) files.
+
+
‘-movflags faststart’
+
Run a second pass moving the index (moov atom) to the beginning of the file.
+This operation can take a while, and will not work in various situations such
+as fragmented output, thus it is not enabled by default.
+
+
‘-movflags rtphint’
+
Add RTP hinting tracks to the output file.
+
+
+
+
Smooth Streaming content can be pushed in real time to a publishing
+point on IIS with this muxer. Example:
+
The MP3 muxer writes a raw MP3 stream with an ID3v2 header at the beginning and
+optionally an ID3v1 tag at the end. ID3v2.3 and ID3v2.4 are supported, the
+id3v2_version option controls which one is used. The legacy ID3v1 tag is
+not written by default, but may be enabled with the write_id3v1 option.
+
+
For seekable output the muxer also writes a Xing frame at the beginning, which
+contains the number of frames in the file. It is useful for computing duration
+of VBR files.
+
+
The muxer supports writing ID3v2 attached pictures (APIC frames). The pictures
+are supplied to the muxer in form of a video stream with a single packet. There
+can be any number of those streams, each will correspond to a single APIC frame.
+The stream metadata tags title and comment map to APIC
+description and picture type respectively. See
+http://id3.org/id3v2.4.0-frames for allowed picture types.
+
+
Note that the APIC frames must be written at the beginning, so the muxer will
+buffer the audio frames until it gets all the pictures. It is therefore advised
+to provide the pictures as soon as possible to avoid excessive buffering.
+
+
Examples:
+
+
Write an mp3 with an ID3v2.3 header and an ID3v1 footer:
+
This muxer implements ISO 13818-1 and part of ETSI EN 300 468.
+
+
The muxer options are:
+
+
+
‘-mpegts_original_network_id number’
+
Set the original_network_id (default 0x0001). This is unique identifier
+of a network in DVB. Its main use is in the unique identification of a
+service through the path Original_Network_ID, Transport_Stream_ID.
+
+
‘-mpegts_transport_stream_id number’
+
Set the transport_stream_id (default 0x0001). This identifies a
+transponder in DVB.
+
+
‘-mpegts_service_id number’
+
Set the service_id (default 0x0001) also known as program in DVB.
+
+
‘-mpegts_pmt_start_pid number’
+
Set the first PID for PMT (default 0x1000, max 0x1f00).
+
+
‘-mpegts_start_pid number’
+
Set the first PID for data packets (default 0x0100, max 0x0f00).
+
+
‘-mpegts_m2ts_mode number’
+
Enable m2ts mode if set to 1. Default value is -1 which disables m2ts mode.
+
+
‘-muxrate number’
+
Set muxrate.
+
+
‘-pes_payload_size number’
+
Set minimum PES packet payload in bytes.
+
+
‘-mpegts_flags flags’
+
Set flags (see below).
+
+
‘-mpegts_copyts number’
+
Preserve original timestamps, if value is set to 1. Default value is -1, which
+results in shifting timestamps so that they start from 0.
+
+
‘-tables_version number’
+
Set PAT, PMT and SDT version (default 0, valid values are from 0 to 31, inclusively).
+This option allows updating stream structure so that standard consumer may
+detect the change. To do so, reopen output AVFormatContext (in case of API
+usage) or restart ffmpeg instance, cyclically changing tables_version value:
+
Option mpegts_flags may take a set of such flags:
+
+
+
‘resend_headers’
+
Reemit PAT/PMT before writing the next packet.
+
+
‘latm’
+
Use LATM packetization for AAC.
+
+
+
+
The recognized metadata settings in mpegts muxer are service_provider
+and service_name. If they are not set the default for
+service_provider is "FFmpeg" and the default for
+service_name is "Service01".
+
Preferred page duration, in microseconds. The muxer will attempt to create
+pages that are approximately duration microseconds long. This allows the
+user to compromise between seek granularity and container overhead. The default
+is 1 second. A value of 0 will fill all segments, making pages as large as
+possible. A value of 1 will effectively use 1 packet-per-page in most
+situations, giving a small seek granularity at the cost of additional container
+overhead.
+
The segmenter muxer outputs streams to a number of separate files of nearly
+fixed duration. Output filename pattern can be set in a fashion similar to
+image2.
+
+
stream_segment is a variant of the muxer used to write to
+streaming output formats, i.e. which do not require global headers,
+and is recommended for outputting e.g. to MPEG transport stream segments.
+ssegment is a shorter alias for stream_segment.
+
+
Every segment starts with a keyframe of the selected reference stream,
+which is set through the ‘reference_stream’ option.
+
+
Note that if you want accurate splitting for a video file, you need to
+make the input key frames correspond to the exact splitting times
+expected by the segmenter, or the segment muxer will start the new
+segment with the key frame found next after the specified start
+time.
+
+
The segment muxer works best with a single constant frame rate video.
+
+
Optionally it can generate a list of the created segments, by setting
+the option segment_list. The list type is specified by the
+segment_list_type option.
+
+
The segment muxer supports the following options:
+
+
+
‘reference_stream specifier’
+
Set the reference stream, as specified by the string specifier.
+If specifier is set to auto, the reference is choosen
+automatically. Otherwise it must be a stream specifier (see the “Stream
+specifiers” chapter in the ffmpeg manual) which specifies the
+reference stream. The default value is auto.
+
+
+
‘segment_format format’
+
Override the inner container format, by default it is guessed by the filename
+extension.
+
+
+
‘segment_list name’
+
Generate also a listfile named name. If not specified no
+listfile is generated.
+
+
+
‘segment_list_flags flags’
+
Set flags affecting the segment list generation.
+
+
It currently supports the following flags:
+
+
‘cache’
+
Allow caching (only affects M3U8 list files).
+
+
+
‘live’
+
Allow live-friendly file generation.
+
+
+
+
Default value is samp.
+
+
+
‘segment_list_size size’
+
Update the list file so that it contains at most the last size
+segments. If 0 the list file will contain all the segments. Default
+value is 0.
+
+
+
‘segment_list_type type’
+
Specify the format for the segment list file.
+
+
The following values are recognized:
+
+
‘flat’
+
Generate a flat list for the created segments, one segment per line.
+
+
+
‘csv, ext’
+
Generate a list for the created segments, one segment per line,
+each line matching the format (comma-separated values):
+
segment_filename is the name of the output file generated by the
+muxer according to the provided pattern. CSV escaping (according to
+RFC4180) is applied if required.
+
+
segment_start_time and segment_end_time specify
+the segment start and end time expressed in seconds.
+
+
A list file with the suffix ".csv" or ".ext" will
+auto-select this format.
+
+
‘ext’ is deprecated in favor or ‘csv’.
+
+
+
‘ffconcat’
+
Generate an ffconcat file for the created segments. The resulting file
+can be read using the FFmpeg concat demuxer.
+
+
A list file with the suffix ".ffcat" or ".ffconcat" will
+auto-select this format.
+
A list file with the suffix ".m3u8" will auto-select this format.
+
+
+
+
If not specified the type is guessed from the list file name suffix.
+
+
+
‘segment_time time’
+
Set segment duration to time, the value must be a duration
+specification. Default value is "2". See also the
+‘segment_times’ option.
+
+
Note that splitting may not be accurate, unless you force the
+reference stream key-frames at the given time. See the introductory
+notice and the examples below.
+
+
+
‘segment_time_delta delta’
+
Specify the accuracy time when selecting the start time for a
+segment, expressed as a duration specification. Default value is "0".
+
+
When delta is specified a key-frame will start a new segment if its
+PTS satisfies the relation:
+
PTS >= start_time - time_delta
+
+
+
This option is useful when splitting video content, which is always
+split at GOP boundaries, in case a key frame is found just before the
+specified split time.
+
+
In particular may be used in combination with the ‘ffmpeg’ option
+force_key_frames. The key frame times specified by
+force_key_frames may not be set accurately because of rounding
+issues, with the consequence that a key frame time may result set just
+before the specified time. For constant frame rate videos a value of
+1/2*frame_rate should address the worst case mismatch between
+the specified time and the time set by force_key_frames.
+
+
+
‘segment_times times’
+
Specify a list of split points. times contains a list of comma
+separated duration specifications, in increasing order. See also
+the ‘segment_time’ option.
+
+
+
‘segment_frames frames’
+
Specify a list of split video frame numbers. frames contains a
+list of comma separated integer numbers, in increasing order.
+
+
This option specifies to start a new segment whenever a reference
+stream key frame is found and the sequential number (starting from 0)
+of the frame is greater or equal to the next value in the list.
+
+
+
‘segment_wrap limit’
+
Wrap around segment index once it reaches limit.
+
+
+
‘segment_start_number number’
+
Set the sequence number of the first segment. Defaults to 0.
+
+
+
‘reset_timestamps 1|0’
+
Reset timestamps at the begin of each segment, so that each segment
+will start with near-zero timestamps. It is meant to ease the playback
+of the generated segments. May not work with some combinations of
+muxers/codecs. It is set to 0 by default.
+
+
+
‘initial_offset offset’
+
Specify timestamp offset to apply to the output packet timestamps. The
+argument must be a time duration specification, and defaults to 0.
+
+To remux the content of file ‘in.mkv’ to a list of segments
+‘out-000.nut’, ‘out-001.nut’, etc., and write the list of
+generated segments to ‘out.list’:
+
+As the example above, but use the ffmpeg ‘force_key_frames’
+option to force key frames in the input at the specified location, together
+with the segment option ‘segment_time_delta’ to account for
+possible roundings operated when setting key frame times.
+
The tee muxer can be used to write the same data to several files or any
+other kind of muxer. It can be used, for example, to both stream a video to
+the network and save it to disk at the same time.
+
+
It is different from specifying several outputs to the ffmpeg
+command-line tool because the audio and video data will be encoded only once
+with the tee muxer; encoding can be a very expensive process. It is not
+useful when using the libavformat API directly because it is then possible
+to feed the same packets to several muxers directly.
+
+
The slave outputs are specified in the file name given to the muxer,
+separated by ’|’. If any of the slave name contains the ’|’ separator,
+leading or trailing spaces or any special character, it must be
+escaped (see the “Quoting and escaping” section in the ffmpeg-utils
+manual).
+
+
Muxer options can be specified for each slave by prepending them as a list of
+key=value pairs separated by ’:’, between square brackets. If
+the options values contain a special character or the ’:’ separator, they
+must be escaped; note that this is a second level escaping.
+
+
The following special options are also recognized:
+
+
‘f’
+
Specify the format name. Useful if it cannot be guessed from the
+output name suffix.
+
+
+
‘bsfs[/spec]’
+
Specify a list of bitstream filters to apply to the specified
+output. It is possible to specify to which streams a given bitstream
+filter applies, by appending a stream specifier to the option
+separated by /. If the stream specifier is not specified, the
+bistream filters will be applied to all streams in the output.
+
+
Several bitstream filters can be specified, separated by ",".
+
+
+
‘select’
+
Select the streams that should be mapped to the slave output,
+specified by a stream specifier. If not specified, this defaults to
+all the input streams.
+
+
+
+
Some examples follow.
+
+
+Encode something and both archive it in a WebM file and stream it
+as MPEG-TS over UDP (the streams need to be explicitly mapped):
+
+Use ffmpeg to encode the input, and send the output
+to three different destinations. The dump_extra bitstream
+filter is used to add extradata information to all the output video
+keyframes packets, as requested by the MPEG-TS format. The select
+option is applied to ‘out.aac’ in order to make it contain only
+audio packets.
+
Note: some codecs may need different options depending on the output format;
+the auto-detection of this can not work with the tee muxer. The main example
+is the ‘global_header’ flag.
+
FFmpeg is able to dump metadata from media files into a simple UTF-8-encoded
+INI-like text file and then load it back using the metadata muxer/demuxer.
+
+
The file format is as follows:
+
+
+A file consists of a header and a number of metadata tags divided into sections,
+each on its own line.
+
+
+The header is a ’;FFMETADATA’ string, followed by a version number (now 1).
+
+
+Metadata tags are of the form ’key=value’
+
+
+Immediately after header follows global metadata
+
+
+After global metadata there may be sections with per-stream/per-chapter
+metadata.
+
+
+A section starts with the section name in uppercase (i.e. STREAM or CHAPTER) in
+brackets (’[’, ’]’) and ends with next section or end of file.
+
+
+At the beginning of a chapter section there may be an optional timebase to be
+used for start/end values. It must be in form ’TIMEBASE=num/den’, where num and
+den are integers. If the timebase is missing then start/end times are assumed to
+be in milliseconds.
+Next a chapter section must contain chapter start and end times in form
+’START=num’, ’END=num’, where num is a positive integer.
+
+
+Empty lines and lines starting with ’;’ or ’#’ are ignored.
+
+
+Metadata keys or values containing special characters (’=’, ’;’, ’#’, ’\’ and a
+newline) must be escaped with a backslash ’\’.
+
+
+Note that whitespace in metadata (e.g. foo = bar) is considered to be a part of
+the tag (in the example above key is ’foo ’, value is ’ bar’).
+
+
+
A ffmetadata file might look like this:
+
;FFMETADATA1
+title=bike\\shed
+;this is a comment
+artist=FFmpeg troll team
+
+[CHAPTER]
+TIMEBASE=1/1000
+START=0
+#chapter ends at 0:01:00
+END=60000
+title=chapter \#1
+[STREAM]
+title=multi\
+line
+
+
+
By using the ffmetadata muxer and demuxer it is possible to extract
+metadata from an input file to an ffmetadata file, and then transcode
+the file into an output file with the edited ffmetadata file.
+
+
Extracting an ffmetadata file with ‘ffmpeg’ goes as follows:
+
ffmpeg -i INPUT -f ffmetadata FFMETADATAFILE
+
+
+
Reinserting edited metadata information from the FFMETADATAFILE file can
+be done as:
+
Protocols are configured elements in FFmpeg that enable access to
+resources that require specific protocols.
+
+
When you configure your FFmpeg build, all the supported protocols are
+enabled by default. You can list all available ones using the
+configure option "–list-protocols".
+
+
You can disable all the protocols using the configure option
+"–disable-protocols", and selectively enable a protocol using the
+option "–enable-protocol=PROTOCOL", or you can disable a
+particular protocol using the option
+"–disable-protocol=PROTOCOL".
+
+
The option "-protocols" of the ff* tools will display the list of
+supported protocols.
+
+
A description of the currently available protocols follows.
+
For example to read from a file ‘input.mpeg’ with ffmpeg
+use the command:
+
ffmpeg -i file:input.mpeg output.mpeg
+
+
+
The ff* tools default to the file protocol, that is a resource
+specified with the name "FILE.mpeg" is interpreted as the URL
+"file:FILE.mpeg".
+
+
This protocol accepts the following options:
+
+
+
‘truncate’
+
Truncate existing files on write, if set to 1. A value of 0 prevents
+truncating. Default value is 1.
+
+
+
‘blocksize’
+
Set I/O operation maximum block size, in bytes. Default value is
+INT_MAX, which results in not limiting the requested block size.
+Setting this value reasonably low improves user termination request reaction
+time, which is valuable for files on slow medium.
+
Set timeout of socket I/O operations used by the underlying low level
+operation. By default it is set to -1, which means that the timeout is
+not specified.
+
+
+
‘ftp-anonymous-password’
+
Password used when login as anonymous user. Typically an e-mail address
+should be used.
+
+
+
‘ftp-write-seekable’
+
Control seekability of connection during encoding. If set to 1 the
+resource is supposed to be seekable, if set to 0 it is assumed not
+to be seekable. Default value is 0.
+
+
+
+
NOTE: Protocol can be used as output, but it is recommended to not do
+it, unless special care is taken (tests, customized server configuration
+etc.). Different FTP servers behave in different way during seek
+operation. ff* tools may produce incomplete content due to server limitations.
+
Read Apple HTTP Live Streaming compliant segmented stream as
+a uniform one. The M3U8 playlists describing the segments can be
+remote HTTP resources or local files, accessed using the standard
+file protocol.
+The nested protocol is declared by specifying
+"+proto" after the hls URI scheme name, where proto
+is either "file" or "http".
+
Using this protocol is discouraged - the hls demuxer should work
+just as well (if not, please report the issues) and is more complete.
+To use the hls demuxer instead, simply use the direct URLs to the
+m3u8 files.
+
Control seekability of connection. If set to 1 the resource is
+supposed to be seekable, if set to 0 it is assumed not to be seekable,
+if set to -1 it will try to autodetect if it is seekable. Default
+value is -1.
+
+
+
‘chunked_post’
+
If set to 1 use chunked transfer-encoding for posts, default is 1.
+
+
+
‘headers’
+
Set custom HTTP headers, can override built in default headers. The
+value must be a string encoding the headers.
+
+
+
‘content_type’
+
Force a content type.
+
+
+
‘user-agent’
+
Override User-Agent header. If not specified the protocol will use a
+string describing the libavformat build.
+
+
+
‘multiple_requests’
+
Use persistent connections if set to 1. By default it is 0.
+
+
+
‘post_data’
+
Set custom HTTP post data.
+
+
+
‘timeout’
+
Set timeout of socket I/O operations used by the underlying low level
+operation. By default it is set to -1, which means that the timeout is
+not specified.
+
+
+
‘mime_type’
+
Set MIME type.
+
+
+
‘icy’
+
If set to 1 request ICY (SHOUTcast) metadata from the server. If the server
+supports this, the metadata has to be retrieved by the application by reading
+the ‘icy_metadata_headers’ and ‘icy_metadata_packet’ options.
+The default is 0.
+
+
+
‘icy_metadata_headers’
+
If the server supports ICY metadata, this contains the ICY specific HTTP reply
+headers, separated with newline characters.
+
+
+
‘icy_metadata_packet’
+
If the server supports ICY metadata, and ‘icy’ was set to 1, this
+contains the last non-empty metadata packet sent by the server.
+
+
+
‘cookies’
+
Set the cookies to be sent in future requests. The format of each cookie is the
+same as the value of a Set-Cookie HTTP response field. Multiple cookies can be
+delimited by a newline character.
+
Some HTTP requests will be denied unless cookie values are passed in with the
+request. The ‘cookies’ option allows these cookies to be specified. At
+the very least, each cookie must specify a value along with a path and domain.
+HTTP requests that match both the domain and path will automatically include the
+cookie value in the HTTP Cookie header field. Multiple cookies can be delimited
+by a newline.
+
+
The required syntax to play a stream specifying a cookie is:
+
Computes the MD5 hash of the data to be written, and on close writes
+this to the designated output or stdout if none is specified. It can
+be used to test muxers without writing an actual file.
+
+
Some examples follow.
+
# Write the MD5 hash of the encoded AVI file to the file output.avi.md5.
+ffmpeg -i input.flv -f avi -y md5:output.avi.md5
+
+# Write the MD5 hash of the encoded AVI file to stdout.
+ffmpeg -i input.flv -f avi -y md5:
+
+
+
Note that some formats (typically MOV) require the output protocol to
+be seekable, so they will fail with the MD5 output protocol.
+
number is the number corresponding to the file descriptor of the
+pipe (e.g. 0 for stdin, 1 for stdout, 2 for stderr). If number
+is not specified, by default the stdout file descriptor will be used
+for writing, stdin for reading.
+
+
For example to read from stdin with ffmpeg:
+
cat test.wav | ffmpeg -i pipe:0
+# ...this is the same as...
+cat test.wav | ffmpeg -i pipe:
+
+
+
For writing to stdout with ffmpeg:
+
ffmpeg -i test.wav -f avi pipe:1 | cat > test.avi
+# ...this is the same as...
+ffmpeg -i test.wav -f avi pipe: | cat > test.avi
+
+
+
This protocol accepts the following options:
+
+
+
‘blocksize’
+
Set I/O operation maximum block size, in bytes. Default value is
+INT_MAX, which results in not limiting the requested block size.
+Setting this value reasonably low improves user termination request reaction
+time, which is valuable if data transmission is slow.
+
+
+
+
Note that some formats (typically MOV), require the output protocol to
+be seekable, so they will fail with the pipe output protocol.
+
The number of the TCP port to use (by default is 1935).
+
+
+
‘app’
+
It is the name of the application to access. It usually corresponds to
+the path where the application is installed on the RTMP server
+(e.g. ‘/ondemand/’, ‘/flash/live/’, etc.). You can override
+the value parsed from the URI through the rtmp_app option, too.
+
+
+
‘playpath’
+
It is the path or name of the resource to play with reference to the
+application specified in app, may be prefixed by "mp4:". You
+can override the value parsed from the URI through the rtmp_playpath
+option, too.
+
+
+
‘listen’
+
Act as a server, listening for an incoming connection.
+
+
+
‘timeout’
+
Maximum time to wait for the incoming connection. Implies listen.
+
+
+
+
Additionally, the following parameters can be set via command line options
+(or in code via AVOptions):
+
+
‘rtmp_app’
+
Name of application to connect on the RTMP server. This option
+overrides the parameter specified in the URI.
+
+
+
‘rtmp_buffer’
+
Set the client buffer time in milliseconds. The default is 3000.
+
+
+
‘rtmp_conn’
+
Extra arbitrary AMF connection parameters, parsed from a string,
+e.g. like B:1 S:authMe O:1 NN:code:1.23 NS:flag:ok O:0.
+Each value is prefixed by a single character denoting the type,
+B for Boolean, N for number, S for string, O for object, or Z for null,
+followed by a colon. For Booleans the data must be either 0 or 1 for
+FALSE or TRUE, respectively. Likewise for Objects the data must be 0 or
+1 to end or begin an object, respectively. Data items in subobjects may
+be named, by prefixing the type with ’N’ and specifying the name before
+the value (i.e. NB:myFlag:1). This option may be used multiple
+times to construct arbitrary AMF sequences.
+
+
+
‘rtmp_flashver’
+
Version of the Flash plugin used to run the SWF player. The default
+is LNX 9,0,124,2. (When publishing, the default is FMLE/3.0 (compatible;
+<libavformat version>).)
+
+
+
‘rtmp_flush_interval’
+
Number of packets flushed in the same request (RTMPT only). The default
+is 10.
+
+
+
‘rtmp_live’
+
Specify that the media is a live stream. No resuming or seeking in
+live streams is possible. The default value is any, which means the
+subscriber first tries to play the live stream specified in the
+playpath. If a live stream of that name is not found, it plays the
+recorded stream. The other possible values are live and
+recorded.
+
+
+
‘rtmp_pageurl’
+
URL of the web page in which the media was embedded. By default no
+value will be sent.
+
+
+
‘rtmp_playpath’
+
Stream identifier to play or to publish. This option overrides the
+parameter specified in the URI.
+
+
+
‘rtmp_subscribe’
+
Name of live stream to subscribe to. By default no value will be sent.
+It is only sent if the option is specified or if rtmp_live
+is set to live.
+
+
+
‘rtmp_swfhash’
+
SHA256 hash of the decompressed SWF file (32 bytes).
+
+
+
‘rtmp_swfsize’
+
Size of the decompressed SWF file, required for SWFVerification.
+
+
+
‘rtmp_swfurl’
+
URL of the SWF player for the media. By default no value will be sent.
+
+
+
‘rtmp_swfverify’
+
URL to player swf file, compute hash/size automatically.
+
+
+
‘rtmp_tcurl’
+
URL of the target stream. Defaults to proto://host[:port]/app.
+
+
+
+
+
For example to read with ffplay a multimedia resource named
+"sample" from the application "vod" from an RTMP server "myserver":
+
ffplay rtmp://myserver/vod/sample
+
+
+
To publish to a password protected server, passing the playpath and
+app names separately:
+
The Encrypted Real-Time Messaging Protocol (RTMPE) is used for
+streaming multimedia content within standard cryptographic primitives,
+consisting of Diffie-Hellman key exchange and HMACSHA256, generating
+a pair of RC4 keys.
+
Real-Time Messaging Protocol tunneled through HTTP.
+
+
The Real-Time Messaging Protocol tunneled through HTTP (RTMPT) is used
+for streaming multimedia content within HTTP requests to traverse
+firewalls.
+
Encrypted Real-Time Messaging Protocol tunneled through HTTP.
+
+
The Encrypted Real-Time Messaging Protocol tunneled through HTTP (RTMPTE)
+is used for streaming multimedia content within HTTP requests to traverse
+firewalls.
+
Real-Time Messaging Protocol tunneled through HTTPS.
+
+
The Real-Time Messaging Protocol tunneled through HTTPS (RTMPTS) is used
+for streaming multimedia content within HTTPS requests to traverse
+firewalls.
+
Set timeout of socket I/O operations used by the underlying low level
+operation. By default it is set to -1, which means that the timeout
+is not specified.
+
+
+
‘truncate’
+
Truncate existing files on write, if set to 1. A value of 0 prevents
+truncating. Default value is 1.
+
Real-Time Messaging Protocol and its variants supported through
+librtmp.
+
+
Requires the presence of the librtmp headers and library during
+configuration. You need to explicitly configure the build with
+"–enable-librtmp". If enabled this will replace the native RTMP
+protocol.
+
+
This protocol provides most client functions and a few server
+functions needed to support RTMP, RTMP tunneled in HTTP (RTMPT),
+encrypted RTMP (RTMPE), RTMP over SSL/TLS (RTMPS) and tunneled
+variants of these encrypted types (RTMPTE, RTMPTS).
+
where rtmp_proto is one of the strings "rtmp", "rtmpt", "rtmpe",
+"rtmps", "rtmpte", "rtmpts" corresponding to each RTMP variant, and
+server, port, app and playpath have the same
+meaning as specified for the RTMP native protocol.
+options contains a list of space-separated options of the form
+key=val.
+
+
See the librtmp manual page (man 3 librtmp) for more information.
+
+
For example, to stream a file in real-time to an RTMP server using
+ffmpeg:
+
RTSP is not technically a protocol handler in libavformat, it is a demuxer
+and muxer. The demuxer supports both normal RTSP (with data transferred
+over RTP; this is used by e.g. Apple and Microsoft) and Real-RTSP (with
+data transferred over RDT).
+
+
The muxer can be used to send a stream using RTSP ANNOUNCE to a server
+supporting it (currently Darwin Streaming Server and Mischa Spiegelmock’s
+RTSP server).
+
+
The required syntax for a RTSP url is:
+
rtsp://hostname[:port]/path
+
+
+
The following options (set on the ffmpeg/ffplay command
+line, or set in code via AVOptions or in avformat_open_input),
+are supported:
+
+
Flags for rtsp_transport:
+
+
+
‘udp’
+
Use UDP as lower transport protocol.
+
+
+
‘tcp’
+
Use TCP (interleaving within the RTSP control channel) as lower
+transport protocol.
+
+
+
‘udp_multicast’
+
Use UDP multicast as lower transport protocol.
+
+
+
‘http’
+
Use HTTP tunneling as lower transport protocol, which is useful for
+passing proxies.
+
+
+
+
Multiple lower transport protocols may be specified, in that case they are
+tried one at a time (if the setup of one fails, the next one is tried).
+For the muxer, only the tcp and udp options are supported.
+
+
Flags for rtsp_flags:
+
+
+
‘filter_src’
+
Accept packets only from negotiated peer address and port.
+
+
‘listen’
+
Act as a server, listening for an incoming connection.
+
+
+
+
When receiving data over UDP, the demuxer tries to reorder received packets
+(since they may arrive out of order, or packets may get lost totally). This
+can be disabled by setting the maximum demuxing delay to zero (via
+the max_delay field of AVFormatContext).
+
+
When watching multi-bitrate Real-RTSP streams with ffplay, the
+streams to display can be chosen with -vstn and
+-astn for video and audio respectively, and can be switched
+on the fly by pressing v and a.
+
+
Example command lines:
+
+
To watch a stream over UDP, with a max reordering delay of 0.5 seconds:
+
Session Announcement Protocol (RFC 2974). This is not technically a
+protocol handler in libavformat, it is a muxer and demuxer.
+It is used for signalling of RTP streams, by announcing the SDP for the
+streams regularly on a separate port.
+
The RTP packets are sent to destination on port port,
+or to port 5004 if no port is specified.
+options is a &-separated list. The following options
+are supported:
+
+
+
‘announce_addr=address’
+
Specify the destination IP address for sending the announcements to.
+If omitted, the announcements are sent to the commonly used SAP
+announcement multicast address 224.2.127.254 (sap.mcast.net), or
+ff0e::2:7ffe if destination is an IPv6 address.
+
+
+
‘announce_port=port’
+
Specify the port to send the announcements on, defaults to
+9875 if not specified.
+
+
+
‘ttl=ttl’
+
Specify the time to live value for the announcements and RTP packets,
+defaults to 255.
+
+
+
‘same_port=0|1’
+
If set to 1, send all RTP streams on the same port pair. If zero (the
+default), all streams are sent on unique ports, with each stream on a
+port 2 numbers higher than the previous.
+VLC/Live555 requires this to be set to 1, to be able to receive the stream.
+The RTP stack in libavformat for receiving requires all streams to be sent
+on unique ports.
+
+
+
+
Example command lines follow.
+
+
To broadcast a stream on the local subnet, for watching in VLC:
+
+
ffmpeg -re -i input -f sap sap://224.0.0.255?same_port=1
+
+
+
Similarly, for watching in ffplay:
+
+
ffmpeg -re -i input -f sap sap://224.0.0.255
+
+
+
And for watching in ffplay, over IPv6:
+
+
ffmpeg -re -i input -f sap sap://[ff0e::1:2:3:4]
+
The syntax for a SAP url given to the demuxer is:
+
sap://[address][:port]
+
+
+
address is the multicast address to listen for announcements on,
+if omitted, the default 224.2.127.254 (sap.mcast.net) is used. port
+is the port that is listened on, 9875 if omitted.
+
+
The demuxers listens for announcements on the given address and port.
+Once an announcement is received, it tries to receive that particular stream.
+
+
Example command lines follow.
+
+
To play back the first stream announced on the normal SAP multicast address:
+
+
ffplay sap://
+
+
+
To play back the first stream announced on one the default IPv6 SAP multicast address:
+
Set input and output encoding parameters, which are expressed by a
+base64-encoded representation of a binary block. The first 16 bytes of
+this binary block are used as master key, the following 14 bytes are
+used as master salt.
+
In read mode: if no data arrived in more than this time interval, raise error.
+In write mode: if socket cannot be written in more than this time interval, raise error.
+This also sets timeout on TCP connection establishing.
+
+
ffmpeg -i input -f format tcp://hostname:port?listen
+ffplay tcp://hostname:port
+
Transport Layer Security (TLS) / Secure Sockets Layer (SSL)
+
+
The required syntax for a TLS/SSL url is:
+
tls://hostname:port[?options]
+
+
+
The following parameters can be set via command line options
+(or in code via AVOptions):
+
+
+
‘ca_file, cafile=filename’
+
A file containing certificate authority (CA) root certificates to treat
+as trusted. If the linked TLS library contains a default this might not
+need to be specified for verification to work, but not all libraries and
+setups have defaults built in.
+The file must be in OpenSSL PEM format.
+
+
+
‘tls_verify=1|0’
+
If enabled, try to verify the peer that we are communicating with.
+Note, if using OpenSSL, this currently only makes sure that the
+peer certificate is signed by one of the root certificates in the CA
+database, but it does not validate that the certificate actually
+matches the host name we are trying to connect to. (With GnuTLS,
+the host name is validated as well.)
+
+
This is disabled by default since it requires a CA database to be
+provided by the caller in many cases.
+
+
+
‘cert_file, cert=filename’
+
A file containing a certificate to use in the handshake with the peer.
+(When operating as server, in listen mode, this is more often required
+by the peer, while client certificates only are mandated in certain
+setups.)
+
+
+
‘key_file, key=filename’
+
A file containing the private key for the certificate.
+
+
+
‘listen=1|0’
+
If enabled, listen for connections on the provided port, and assume
+the server role in the handshake instead of the client role.
+
+
+
+
+
Example command lines:
+
+
To create a TLS/SSL server that serves an input stream.
+
+
ffmpeg -i input -f format tls://hostname:port?listen&cert=server.crt&key=server.key
+
+
+
To play back a stream from the TLS/SSL server using ffplay:
+
options contains a list of &-separated options of the form key=val.
+
+
In case threading is enabled on the system, a circular buffer is used
+to store the incoming data, which allows to reduce loss of data due to
+UDP socket buffer overruns. The fifo_size and
+overrun_nonfatal options are related to this buffer.
+
+
The list of supported options follows.
+
+
+
‘buffer_size=size’
+
Set the UDP socket buffer size in bytes. This is used both for the
+receiving and the sending buffer size.
+
+
+
‘localport=port’
+
Override the local UDP port to bind with.
+
+
+
‘localaddr=addr’
+
Choose the local IP address. This is useful e.g. if sending multicast
+and the host has multiple interfaces, where the user can choose
+which interface to send on by specifying the IP address of that interface.
+
+
+
‘pkt_size=size’
+
Set the size in bytes of UDP packets.
+
+
+
‘reuse=1|0’
+
Explicitly allow or disallow reusing UDP sockets.
+
+
+
‘ttl=ttl’
+
Set the time to live value (for multicast only).
+
+
+
‘connect=1|0’
+
Initialize the UDP socket with connect(). In this case, the
+destination address can’t be changed with ff_udp_set_remote_url later.
+If the destination address isn’t known at the start, this option can
+be specified in ff_udp_set_remote_url, too.
+This allows finding out the source address for the packets with getsockname,
+and makes writes return with AVERROR(ECONNREFUSED) if "destination
+unreachable" is received.
+For receiving, this gives the benefit of only receiving packets from
+the specified peer address/port.
+
+
+
‘sources=address[,address]’
+
Only receive packets sent to the multicast group from one of the
+specified sender IP addresses.
+
+
+
‘block=address[,address]’
+
Ignore packets sent to the multicast group from the specified
+sender IP addresses.
+
+
+
‘fifo_size=units’
+
Set the UDP receiving circular buffer size, expressed as a number of
+packets with size of 188 bytes. If not specified defaults to 7*4096.
+
+
+
‘overrun_nonfatal=1|0’
+
Survive in case of UDP receiving circular buffer overrun. Default
+value is 0.
+
+
+
‘timeout=microseconds’
+
In read mode: if no data arrived in more than this time interval, raise error.
+
+
+
+
Some usage examples of the UDP protocol with ffmpeg follow.
+
+
To stream over UDP to a remote endpoint:
+
ffmpeg -i input -f format udp://hostname:port
+
+
+
To stream in mpegts format over UDP using 188 sized UDP packets, using a large input buffer:
+
The libavdevice library provides the same interface as
+libavformat. Namely, an input device is considered like a demuxer, and
+an output device like a muxer, and the interface and generic device
+options are the same provided by libavformat (see the ffmpeg-formats
+manual).
+
+
In addition each input or output device may support so-called private
+options, which are specific for that component.
+
+
Options may be set by specifying -optionvalue in the
+FFmpeg tools, or by setting the value explicitly in the device
+AVFormatContext options or using the ‘libavutil/opt.h’ API
+for programmatic use.
+
Input devices are configured elements in FFmpeg which allow to access
+the data coming from a multimedia device attached to your system.
+
+
When you configure your FFmpeg build, all the supported input devices
+are enabled by default. You can list all available ones using the
+configure option "–list-indevs".
+
+
You can disable all the input devices using the configure option
+"–disable-indevs", and selectively enable an input device using the
+option "–enable-indev=INDEV", or you can disable a particular
+input device using the option "–disable-indev=INDEV".
+
+
The option "-formats" of the ff* tools will display the list of
+supported input devices (amongst the demuxers).
+
+
A description of the currently available input devices follows.
+
If no options are specified, the device’s defaults are used.
+If the device does not support the requested options, it will
+fail to open.
+
+
+
‘video_size’
+
Set the video size in the captured video.
+
+
+
‘framerate’
+
Set the frame rate in the captured video.
+
+
+
‘sample_rate’
+
Set the sample rate (in Hz) of the captured audio.
+
+
+
‘sample_size’
+
Set the sample size (in bits) of the captured audio.
+
+
+
‘channels’
+
Set the number of channels in the captured audio.
+
+
+
‘list_devices’
+
If set to ‘true’, print a list of devices and exit.
+
+
+
‘list_options’
+
If set to ‘true’, print a list of selected device’s options
+and exit.
+
+
+
‘video_device_number’
+
Set video device number for devices with same name (starts at 0,
+defaults to 0).
+
+
+
‘audio_device_number’
+
Set audio device number for devices with same name (starts at 0,
+defaults to 0).
+
+
+
‘pixel_format’
+
Select pixel format to be used by DirectShow. This may only be set when
+the video codec is not set or set to rawvideo.
+
+
+
‘audio_buffer_size’
+
Set audio device buffer size in milliseconds (which can directly
+impact latency, depending on the device).
+Defaults to using the audio device’s
+default buffer size (typically some multiple of 500ms).
+Setting this value too low can degrade performance.
+See also
+http://msdn.microsoft.com/en-us/library/windows/desktop/dd377582(v=vs.85).aspx
+
The Linux framebuffer is a graphic hardware-independent abstraction
+layer to show graphics on a computer monitor, typically on the
+console. It is accessed through a file device node, usually
+‘/dev/fb0’.
+
+
For more detailed information read the file
+Documentation/fb/framebuffer.txt included in the Linux source tree.
+
+
To record from the framebuffer device ‘/dev/fb0’ with
+ffmpeg:
+
ffmpeg -f fbdev -r 10 -i /dev/fb0 out.avi
+
+
+
You can take a single screenshot image with the command:
+
To enable this input device, you need libiec61883, libraw1394 and
+libavc1394 installed on your system. Use the configure option
+--enable-libiec61883 to compile with the device enabled.
+
+
The iec61883 capture device supports capturing from a video device
+connected via IEEE1394 (FireWire), using libiec61883 and the new Linux
+FireWire stack (juju). This is the default DV/HDV input method in Linux
+Kernel 2.6.37 and later, since the old FireWire stack was removed.
+
+
Specify the FireWire port to be used as input file, or "auto"
+to choose the first port connected.
+
Override autodetection of DV/HDV. This should only be used if auto
+detection does not work, or if usage of a different device type
+should be prohibited. Treating a DV device as HDV (or vice versa) will
+not work and result in undefined behavior.
+The values ‘auto’, ‘dv’ and ‘hdv’ are supported.
+
+
+
‘dvbuffer’
+
Set maxiumum size of buffer for incoming data, in frames. For DV, this
+is an exact value. For HDV, it is not frame exact, since HDV does
+not have a fixed frame size.
+
+
+
‘dvguid’
+
Select the capture device by specifying it’s GUID. Capturing will only
+be performed from the specified device and fails if no device with the
+given GUID is found. This is useful to select the input if multiple
+devices are connected at the same time.
+Look at /sys/bus/firewire/devices to find out the GUIDs.
+
To enable this input device during configuration you need libjack
+installed on your system.
+
+
A JACK input device creates one or more JACK writable clients, one for
+each audio channel, with name client_name:input_N, where
+client_name is the name provided by the application, and N
+is a number which identifies the channel.
+Each writable client will send the acquired data to the FFmpeg input
+device.
+
+
Once you have created one or more JACK readable clients, you need to
+connect them to one or more JACK writable clients.
+
+
To connect or disconnect JACK clients you can use the jack_connect
+and jack_disconnect programs, or do it through a graphical interface,
+for example with qjackctl.
+
+
To list the JACK clients and their properties you can invoke the command
+jack_lsp.
+
+
Follows an example which shows how to capture a JACK readable client
+with ffmpeg.
+
# Create a JACK writable client with name "ffmpeg".
+$ ffmpeg -f jack -i ffmpeg -y out.wav
+
+# Start the sample jack_metro readable client.
+$ jack_metro -b 120 -d 0.2 -f 4000
+
+# List the current JACK clients.
+$ jack_lsp -c
+system:capture_1
+system:capture_2
+system:playback_1
+system:playback_2
+ffmpeg:input_1
+metro:120_bpm
+
+# Connect metro to the ffmpeg writable client.
+$ jack_connect metro:120_bpm ffmpeg:input_1
+
This input device reads data from the open output pads of a libavfilter
+filtergraph.
+
+
For each filtergraph open output, the input device will create a
+corresponding stream which is mapped to the generated output. Currently
+only video data is supported. The filtergraph is specified through the
+option ‘graph’.
+
Specify the filtergraph to use as input. Each video open output must be
+labelled by a unique string of the form "outN", where N is a
+number starting from 0 corresponding to the mapped input stream
+generated by the device.
+The first unlabelled output is automatically assigned to the "out0"
+label, but all the others need to be specified explicitly.
+
+
If not specified defaults to the filename specified for the input
+device.
+
+
+
‘graph_file’
+
Set the filename of the filtergraph to be read and sent to the other
+filters. Syntax of the filtergraph is the same as the one specified by
+the option graph.
+
The OpenAL input device provides audio capture on all systems with a
+working OpenAL 1.1 implementation.
+
+
To enable this input device during configuration, you need OpenAL
+headers and libraries installed on your system, and need to configure
+FFmpeg with --enable-openal.
+
+
OpenAL headers and libraries should be provided as part of your OpenAL
+implementation, or as an additional download (an SDK). Depending on your
+installation you may need to specify additional flags via the
+--extra-cflags and --extra-ldflags for allowing the build
+system to locate the OpenAL headers and libraries.
+
+
An incomplete list of OpenAL implementations follows:
+
+
+
Creative
+
The official Windows implementation, providing hardware acceleration
+with supported devices and software fallback.
+See http://openal.org/.
+
+
OpenAL Soft
+
Portable, open source (LGPL) software implementation. Includes
+backends for the most common sound APIs on the Windows, Linux,
+Solaris, and BSD operating systems.
+See http://kcat.strangesoft.net/openal.html.
+
This device allows to capture from an audio input device handled
+through OpenAL.
+
+
You need to specify the name of the device to capture in the provided
+filename. If the empty string is provided, the device will
+automatically select the default device. You can get the list of the
+supported devices by using the option list_devices.
+
If FFmpeg is built with v4l-utils support (by using the
+--enable-libv4l2 configure option), it is possible to use it with the
+-use_libv4l2 input device option.
+
+
The name of the device to grab is a file device node, usually Linux
+systems tend to automatically create such nodes when the device
+(e.g. an USB webcam) is plugged into the system, and has a name of the
+kind ‘/dev/videoN’, where N is a number associated to
+the device.
+
+
Video4Linux2 devices usually support a limited set of
+widthxheight sizes and frame rates. You can check which are
+supported using -list_formats all for Video4Linux2 devices.
+Some devices, like TV cards, support one or more standards. It is possible
+to list all the supported standards using -list_standards all.
+
+
The time base for the timestamps is 1 microsecond. Depending on the kernel
+version and configuration, the timestamps may be derived from the real time
+clock (origin at the Unix Epoch) or the monotonic clock (origin usually at
+boot time, unaffected by NTP or manual changes to the clock). The
+‘-timestamps abs’ or ‘-ts abs’ option can be used to force
+conversion into the real time clock.
+
+
Some usage examples of the video4linux2 device with ffmpeg
+and ffplay:
+
+
+Grab and show the input of a video4linux2 device:
+
The filename passed as input is the capture driver number, ranging from
+0 to 9. You may use "list" as filename to print a list of drivers. Any
+other filename will be interpreted as device number 0.
+
hostname:display_number.screen_number specifies the
+X11 display name of the screen to grab from. hostname can be
+omitted, and defaults to "localhost". The environment variable
+DISPLAY contains the default display name.
+
+
x_offset and y_offset specify the offsets of the grabbed
+area with respect to the top-left border of the X11 screen. They
+default to 0.
+
+
Check the X11 documentation (e.g. man X) for more detailed information.
+
+
Use the dpyinfo program for getting basic information about the
+properties of your X11 display (e.g. grep for "name" or "dimensions").
+
Specify whether to draw the mouse pointer. A value of 0 specify
+not to draw the pointer. Default value is 1.
+
+
+
‘follow_mouse’
+
Make the grabbed area follow the mouse. The argument can be
+centered or a number of pixels PIXELS.
+
+
When it is specified with "centered", the grabbing region follows the mouse
+pointer and keeps the pointer at the center of region; otherwise, the region
+follows only when the mouse pointer reaches within PIXELS (greater than
+zero) to the edge of region.
+
Set the grabbing frame rate. Default value is ntsc,
+corresponding to a frame rate of 30000/1001.
+
+
+
‘show_region’
+
Show grabbed region on screen.
+
+
If show_region is specified with 1, then the grabbing
+region will be indicated on screen. With this option, it is easy to
+know what is being grabbed if only a portion of the screen is grabbed.
+
Output devices are configured elements in FFmpeg that can write
+multimedia data to an output device attached to your system.
+
+
When you configure your FFmpeg build, all the supported output devices
+are enabled by default. You can list all available ones using the
+configure option "–list-outdevs".
+
+
You can disable all the output devices using the configure option
+"–disable-outdevs", and selectively enable an output device using the
+option "–enable-outdev=OUTDEV", or you can disable a particular
+input device using the option "–disable-outdev=OUTDEV".
+
+
The option "-formats" of the ff* tools will display the list of
+enabled output devices (amongst the muxers).
+
+
A description of the currently available output devices follows.
+
This output device allows to show a video stream in CACA window.
+Only one CACA window is allowed per application, so you can
+have only one instance of this output device in an application.
+
+
To enable this output device you need to configure FFmpeg with
+--enable-libcaca.
+libcaca is a graphics library that outputs text instead of pixels.
+
Set the CACA window title, if not specified default to the filename
+specified for the output device.
+
+
+
‘window_size’
+
Set the CACA window size, can be a string of the form
+widthxheight or a video size abbreviation.
+If not specified it defaults to the size of the input video.
+
+
+
‘driver’
+
Set display driver.
+
+
+
‘algorithm’
+
Set dithering algorithm. Dithering is necessary
+because the picture being rendered has usually far more colours than
+the available palette.
+The accepted values are listed with -list_dither algorithms.
+
+
+
‘antialias’
+
Set antialias method. Antialiasing smoothens the rendered
+image and avoids the commonly seen staircase effect.
+The accepted values are listed with -list_dither antialiases.
+
+
+
‘charset’
+
Set which characters are going to be used when rendering text.
+The accepted values are listed with -list_dither charsets.
+
+
+
‘color’
+
Set color to be used when rendering text.
+The accepted values are listed with -list_dither colors.
+
+
+
‘list_drivers’
+
If set to ‘true’, print a list of available drivers and exit.
+
+
+
‘list_dither’
+
List available dither options related to the argument.
+The argument must be one of algorithms, antialiases,
+charsets, colors.
+
The Linux framebuffer is a graphic hardware-independent abstraction
+layer to show graphics on a computer monitor, typically on the
+console. It is accessed through a file device node, usually
+‘/dev/fb0’.
+
+
For more detailed information read the file
+‘Documentation/fb/framebuffer.txt’ included in the Linux source tree.
+
This output device allows to show a video stream in an SDL
+window. Only one SDL window is allowed per application, so you can
+have only one instance of this output device in an application.
+
+
To enable this output device you need libsdl installed on your system
+when configuring your build.
+
Set the SDL window title, if not specified default to the filename
+specified for the output device.
+
+
+
‘icon_title’
+
Set the name of the iconified SDL window, if not specified it is set
+to the same value of window_title.
+
+
+
‘window_size’
+
Set the SDL window size, can be a string of the form
+widthxheight or a video size abbreviation.
+If not specified it defaults to the size of the input video,
+downscaled according to the aspect ratio.
+
+
+
‘window_fullscreen’
+
Set fullscreen mode when non-zero value is provided.
+Zero is a default.
+
Specify the hardware display name, which determines the display and
+communications domain to be used.
+
+
The display name or DISPLAY environment variable can be a string in
+the format hostname[:number[.screen_number]].
+
+
hostname specifies the name of the host machine on which the
+display is physically attached. number specifies the number of
+the display server on that host machine. screen_number specifies
+the screen to be used on that server.
+
+
If unspecified, it defaults to the value of the DISPLAY environment
+variable.
+
+
For example, dual-headed:0.1 would specify screen 1 of display
+0 on the machine named “dual-headed”.
+
+
Check the X11 specification for more detailed information about the
+display name format.
+
+
+
‘window_size’
+
Set the created window size, can be a string of the form
+widthxheight or a video size abbreviation. If not
+specified it defaults to the size of the input video.
+
+
+
‘window_x’
+
‘window_y’
+
Set the X and Y window offsets for the created window. They are both
+set to 0 by default. The values may be ignored by the window manager.
+
+
+
‘window_title’
+
Set the window title, if not specified default to the filename
+specified for the output device.
+
The audio resampler supports the following named options.
+
+
Options may be set by specifying -optionvalue in the
+FFmpeg tools, option=value for the aresample filter,
+by setting the value explicitly in the
+SwrContext options or using the ‘libavutil/opt.h’ API for
+programmatic use.
+
+
+
‘ich, in_channel_count’
+
Set the number of input channels. Default value is 0. Setting this
+value is not mandatory if the corresponding channel layout
+‘in_channel_layout’ is set.
+
+
+
‘och, out_channel_count’
+
Set the number of output channels. Default value is 0. Setting this
+value is not mandatory if the corresponding channel layout
+‘out_channel_layout’ is set.
+
+
+
‘uch, used_channel_count’
+
Set the number of used input channels. Default value is 0. This option is
+only used for special remapping.
+
+
+
‘isr, in_sample_rate’
+
Set the input sample rate. Default value is 0.
+
+
+
‘osr, out_sample_rate’
+
Set the output sample rate. Default value is 0.
+
+
+
‘isf, in_sample_fmt’
+
Specify the input sample format. It is set by default to none.
+
+
+
‘osf, out_sample_fmt’
+
Specify the output sample format. It is set by default to none.
+
+
+
‘tsf, internal_sample_fmt’
+
Set the internal sample format. Default value is none.
+This will automatically be chosen when it is not explicitly set.
+
Set the center mix level. It is a value expressed in deciBel, and must be
+in the interval [-32,32].
+
+
+
‘slev, surround_mix_level’
+
Set the surround mix level. It is a value expressed in deciBel, and must
+be in the interval [-32,32].
+
+
+
‘lfe_mix_level’
+
Set LFE mix into non LFE level. It is used when there is a LFE input but no
+LFE output. It is a value expressed in deciBel, and must
+be in the interval [-32,32].
+
+
+
‘rmvol, rematrix_volume’
+
Set rematrix volume. Default value is 1.0.
+
+
+
‘rematrix_maxval’
+
Set maximum output value for rematrixing.
+This can be used to prevent clipping vs. preventing volumn reduction
+A value of 1.0 prevents cliping.
+
+
+
‘flags, swr_flags’
+
Set flags used by the converter. Default value is 0.
+
+
It supports the following individual flags:
+
+
‘res’
+
force resampling, this flag forces resampling to be used even when the
+input and output sample rates match.
+
+
+
+
+
‘dither_scale’
+
Set the dither scale. Default value is 1.
+
+
+
‘dither_method’
+
Set dither method. Default value is 0.
+
+
Supported values:
+
+
‘rectangular’
+
select rectangular dither
+
+
‘triangular’
+
select triangular dither
+
+
‘triangular_hp’
+
select triangular dither with high pass
+
+
‘lipshitz’
+
select lipshitz noise shaping dither
+
+
‘shibata’
+
select shibata noise shaping dither
+
+
‘low_shibata’
+
select low shibata noise shaping dither
+
+
‘high_shibata’
+
select high shibata noise shaping dither
+
+
‘f_weighted’
+
select f-weighted noise shaping dither
+
+
‘modified_e_weighted’
+
select modified-e-weighted noise shaping dither
+
+
‘improved_e_weighted’
+
select improved-e-weighted noise shaping dither
+
+
+
+
+
+
‘resampler’
+
Set resampling engine. Default value is swr.
+
+
Supported values:
+
+
‘swr’
+
select the native SW Resampler; filter options precision and cheby are not
+applicable in this case.
+
+
‘soxr’
+
select the SoX Resampler (where available); compensation, and filter options
+filter_size, phase_shift, filter_type & kaiser_beta, are not applicable in this
+case.
+
+
+
+
+
‘filter_size’
+
For swr only, set resampling filter size, default value is 32.
+
+
+
‘phase_shift’
+
For swr only, set resampling phase shift, default value is 10, and must be in
+the interval [0,30].
+
+
+
‘linear_interp’
+
Use Linear Interpolation if set to 1, default value is 0.
+
+
+
‘cutoff’
+
Set cutoff frequency (swr: 6dB point; soxr: 0dB point) ratio; must be a float
+value between 0 and 1. Default value is 0.97 with swr, and 0.91 with soxr
+(which, with a sample-rate of 44100, preserves the entire audio band to 20kHz).
+
+
+
‘precision’
+
For soxr only, the precision in bits to which the resampled signal will be
+calculated. The default value of 20 (which, with suitable dithering, is
+appropriate for a destination bit-depth of 16) gives SoX’s ’High Quality’; a
+value of 28 gives SoX’s ’Very High Quality’.
+
+
+
‘cheby’
+
For soxr only, selects passband rolloff none (Chebyshev) & higher-precision
+approximation for ’irrational’ ratios. Default value is 0.
+
+
+
‘async’
+
For swr only, simple 1 parameter audio sync to timestamps using stretching,
+squeezing, filling and trimming. Setting this to 1 will enable filling and
+trimming, larger values represent the maximum amount in samples that the data
+may be stretched or squeezed for each second.
+Default value is 0, thus no compensation is applied to make the samples match
+the audio timestamps.
+
+
+
‘first_pts’
+
For swr only, assume the first pts should be this value. The time unit is 1 / sample rate.
+This allows for padding/trimming at the start of stream. By default, no
+assumption is made about the first frame’s expected pts, so no padding or
+trimming is done. For example, this could be set to 0 to pad the beginning with
+silence if an audio stream starts after the video stream or to trim any samples
+with a negative pts due to encoder delay.
+
+
+
‘min_comp’
+
For swr only, set the minimum difference between timestamps and audio data (in
+seconds) to trigger stretching/squeezing/filling or trimming of the
+data to make it match the timestamps. The default is that
+stretching/squeezing/filling and trimming is disabled
+(‘min_comp’ = FLT_MAX).
+
+
+
‘min_hard_comp’
+
For swr only, set the minimum difference between timestamps and audio data (in
+seconds) to trigger adding/dropping samples to make it match the
+timestamps. This option effectively is a threshold to select between
+hard (trim/fill) and soft (squeeze/stretch) compensation. Note that
+all compensation is by default disabled through ‘min_comp’.
+The default is 0.1.
+
+
+
‘comp_duration’
+
For swr only, set duration (in seconds) over which data is stretched/squeezed
+to make it match the timestamps. Must be a non-negative double float value,
+default value is 1.0.
+
+
+
‘max_soft_comp’
+
For swr only, set maximum factor by which data is stretched/squeezed to make it
+match the timestamps. Must be a non-negative double float value, default value
+is 0.
+
+
+
‘matrix_encoding’
+
Select matrixed stereo encoding.
+
+
It accepts the following values:
+
+
‘none’
+
select none
+
+
‘dolby’
+
select Dolby
+
+
‘dplii’
+
select Dolby Pro Logic II
+
+
+
+
Default value is none.
+
+
+
‘filter_type’
+
For swr only, select resampling filter type. This only affects resampling
+operations.
+
+
It accepts the following values:
+
+
‘cubic’
+
select cubic
+
+
‘blackman_nuttall’
+
select Blackman Nuttall Windowed Sinc
+
+
‘kaiser’
+
select Kaiser Windowed Sinc
+
+
+
+
+
‘kaiser_beta’
+
For swr only, set Kaiser Window Beta value. Must be an integer in the
+interval [2,16], default value is 9.
+
+
+
‘output_sample_bits’
+
For swr only, set number of used output sample bits for dithering. Must be an integer in the
+interval [0,64], default value is 0, which means it’s not used.
+
The video scaler supports the following named options.
+
+
Options may be set by specifying -optionvalue in the
+FFmpeg tools. For programmatic use, they can be set explicitly in the
+SwsContext options or through the ‘libavutil/opt.h’ API.
+
+
+
+
+
+
‘sws_flags’
+
Set the scaler flags. This is also used to set the scaling
+algorithm. Only a single algorithm should be selected.
+
+
It accepts the following values:
+
+
‘fast_bilinear’
+
Select fast bilinear scaling algorithm.
+
+
+
‘bilinear’
+
Select bilinear scaling algorithm.
+
+
+
‘bicubic’
+
Select bicubic scaling algorithm.
+
+
+
‘experimental’
+
Select experimental scaling algorithm.
+
+
+
‘neighbor’
+
Select nearest neighbor rescaling algorithm.
+
+
+
‘area’
+
Select averaging area rescaling algorithm.
+
+
+
‘bicubiclin’
+
Select bicubic scaling algorithm for the luma component, bilinear for
+chroma components.
+
Set source pixel format (must be expressed as an integer).
+
+
+
‘dst_format’
+
Set destination pixel format (must be expressed as an integer).
+
+
+
‘src_range’
+
Select source range.
+
+
+
‘dst_range’
+
Select destination range.
+
+
+
‘param0, param1’
+
Set scaling algorithm parameters. The specified values are specific of
+some scaling algorithms and ignored by others. The specified values
+are floating point number values.
+
+
+
‘sws_dither’
+
Set the dithering algorithm. Accepts one of the following
+values. Default value is ‘auto’.
+
Filtering in FFmpeg is enabled through the libavfilter library.
+
+
In libavfilter, a filter can have multiple inputs and multiple
+outputs.
+To illustrate the sorts of things that are possible, we consider the
+following filtergraph.
+
This filtergraph splits the input stream in two streams, sends one
+stream through the crop filter and the vflip filter before merging it
+back with the other stream by overlaying it on top. You can use the
+following command to achieve this:
+
The result will be that in output the top half of the video is mirrored
+onto the bottom half.
+
+
Filters in the same linear chain are separated by commas, and distinct
+linear chains of filters are separated by semicolons. In our example,
+crop,vflip are in one linear chain, split and
+overlay are separately in another. The points where the linear
+chains join are labelled by names enclosed in square brackets. In the
+example, the split filter generates two outputs that are associated to
+the labels [main] and [tmp].
+
+
The stream sent to the second output of split, labelled as
+[tmp], is processed through the crop filter, which crops
+away the lower half part of the video, and then vertically flipped. The
+overlay filter takes in input the first unchanged output of the
+split filter (which was labelled as [main]), and overlay on its
+lower half the output generated by the crop,vflip filterchain.
+
+
Some filters take in input a list of parameters: they are specified
+after the filter name and an equal sign, and are separated from each other
+by a colon.
+
+
There exist so-called source filters that do not have an
+audio/video input, and sink filters that will not have audio/video
+output.
+
The ‘graph2dot’ program included in the FFmpeg ‘tools’
+directory can be used to parse a filtergraph description and issue a
+corresponding textual representation in the dot language.
+
+
Invoke the command:
+
graph2dot -h
+
+
+
to see how to use ‘graph2dot’.
+
+
You can then pass the dot description to the ‘dot’ program (from
+the graphviz suite of programs) and obtain a graphical representation
+of the filtergraph.
+
can be used to create and display an image representing the graph
+described by the GRAPH_DESCRIPTION string. Note that this string must be
+a complete self-contained graph, with its inputs and outputs explicitly defined.
+For example if your command line is of the form:
+
ffmpeg -i infile -vf scale=640:360 outfile
+
+
your GRAPH_DESCRIPTION string will need to be of the form:
+
nullsrc,scale=640:360,nullsink
+
+
you may also need to set the nullsrc parameters and add a format
+filter in order to simulate a specific input file.
+
A filtergraph is a directed graph of connected filters. It can contain
+cycles, and there can be multiple links between a pair of
+filters. Each link has one input pad on one side connecting it to one
+filter from which it takes its input, and one output pad on the other
+side connecting it to the one filter accepting its output.
+
+
Each filter in a filtergraph is an instance of a filter class
+registered in the application, which defines the features and the
+number of input and output pads of the filter.
+
+
A filter with no input pads is called a "source", a filter with no
+output pads is called a "sink".
+
A filtergraph can be represented using a textual representation, which is
+recognized by the ‘-filter’/‘-vf’ and ‘-filter_complex’
+options in ffmpeg and ‘-vf’ in ffplay, and by the
+avfilter_graph_parse()/avfilter_graph_parse2() function defined in
+‘libavfilter/avfilter.h’.
+
+
A filterchain consists of a sequence of connected filters, each one
+connected to the previous one in the sequence. A filterchain is
+represented by a list of ","-separated filter descriptions.
+
+
A filtergraph consists of a sequence of filterchains. A sequence of
+filterchains is represented by a list of ";"-separated filterchain
+descriptions.
+
+
A filter is represented by a string of the form:
+[in_link_1]...[in_link_N]filter_name=arguments[out_link_1]...[out_link_M]
+
+
filter_name is the name of the filter class of which the
+described filter is an instance of, and has to be the name of one of
+the filter classes registered in the program.
+The name of the filter class is optionally followed by a string
+"=arguments".
+
+
arguments is a string which contains the parameters used to
+initialize the filter instance. It may have one of the following forms:
+
+
+A ’:’-separated list of key=value pairs.
+
+
+A ’:’-separated list of value. In this case, the keys are assumed to be
+the option names in the order they are declared. E.g. the fade filter
+declares three options in this order – ‘type’, ‘start_frame’ and
+‘nb_frames’. Then the parameter list in:0:30 means that the value
+in is assigned to the option ‘type’, 0 to
+‘start_frame’ and 30 to ‘nb_frames’.
+
+
+A ’:’-separated list of mixed direct value and long key=value
+pairs. The direct value must precede the key=value pairs, and
+follow the same constraints order of the previous point. The following
+key=value pairs can be set in any preferred order.
+
+
+
+
If the option value itself is a list of items (e.g. the format filter
+takes a list of pixel formats), the items in the list are usually separated by
+’|’.
+
+
The list of arguments can be quoted using the character "’" as initial
+and ending mark, and the character ’\’ for escaping the characters
+within the quoted text; otherwise the argument string is considered
+terminated when the next special character (belonging to the set
+"[]=;,") is encountered.
+
+
The name and arguments of the filter are optionally preceded and
+followed by a list of link labels.
+A link label allows to name a link and associate it to a filter output
+or input pad. The preceding labels in_link_1
+... in_link_N, are associated to the filter input pads,
+the following labels out_link_1 ... out_link_M, are
+associated to the output pads.
+
+
When two link labels with the same name are found in the
+filtergraph, a link between the corresponding input and output pad is
+created.
+
+
If an output pad is not labelled, it is linked by default to the first
+unlabelled input pad of the next filter in the filterchain.
+For example in the filterchain:
+
nullsrc, split[L1], [L2]overlay, nullsink
+
+
the split filter instance has two output pads, and the overlay filter
+instance two input pads. The first output pad of split is labelled
+"L1", the first input pad of overlay is labelled "L2", and the second
+output pad of split is linked to the second input pad of overlay,
+which are both unlabelled.
+
+
In a complete filterchain all the unlabelled filter input and output
+pads must be connected. A filtergraph is considered valid if all the
+filter input and output pads of all the filterchains are connected.
+
+
Libavfilter will automatically insert scale filters where format
+conversion is required. It is possible to specify swscale flags
+for those automatically inserted scalers by prepending
+sws_flags=flags;
+to the filtergraph description.
+
+
Follows a BNF description for the filtergraph syntax:
+
NAME ::= sequence of alphanumeric characters and '_'
+LINKLABEL ::= "[" NAME "]"
+LINKLABELS ::= LINKLABEL [LINKLABELS]
+FILTER_ARGUMENTS ::= sequence of chars (eventually quoted)
+FILTER ::= [LINKLABELS] NAME ["=" FILTER_ARGUMENTS] [LINKLABELS]
+FILTERCHAIN ::= FILTER [,FILTERCHAIN]
+FILTERGRAPH ::= [sws_flags=flags;] FILTERCHAIN [;FILTERGRAPH]
+
Some filter arguments require the use of special characters, typically
+: to separate key=value pairs in a named options list. In this
+case the user should perform a first level escaping when specifying
+the filter arguments. For example, consider the following literal
+string to be embedded in the drawtext filter arguments:
+
this is a 'string': may contain one, or more, special characters
+
+
+
Since : is special for the filter arguments syntax, it needs to
+be escaped, so you get:
+
text=this is a \'string\'\: may contain one, or more, special characters
+
+
+
A second level of escaping is required when embedding the filter
+arguments in a filtergraph description, in order to escape all the
+filtergraph special characters. Thus the example above becomes:
+
drawtext=text=this is a \\\'string\\\'\\: may contain one\, or more\, special characters
+
+
+
Finally an additional level of escaping may be needed when writing the
+filtergraph description in a shell command, which depends on the
+escaping rules of the adopted shell. For example, assuming that
+\ is special and needs to be escaped with another \, the
+previous string will finally result in:
+
-vf "drawtext=text=this is a \\\\\\'string\\\\\\'\\\\: may contain one\\, or more\\, special characters"
+
+
+
Sometimes, it might be more convenient to employ quoting in place of
+escaping. For example the string:
+
Caesar: tu quoque, Brute, fili mi
+
+
+
Can be quoted in the filter arguments as:
+
text='Caesar: tu quoque, Brute, fili mi'
+
+
+
And finally inserted in a filtergraph like:
+
drawtext=text=\'Caesar: tu quoque\, Brute\, fili mi\'
+
+
+
See the “Quoting and escaping” section in the ffmpeg-utils manual
+for more information about the escaping and quoting rules adopted by
+FFmpeg.
+
Some filters support a generic ‘enable’ option. For the filters
+supporting timeline editing, this option can be set to an expression which is
+evaluated before sending a frame to the filter. If the evaluation is non-zero,
+the filter will be enabled, otherwise the frame will be sent unchanged to the
+next filter in the filtergraph.
+
+
The expression accepts the following values:
+
+
‘t’
+
timestamp expressed in seconds, NAN if the input timestamp is unknown
+
+
+
‘n’
+
sequential number of the input frame, starting from 0
+
+
+
‘pos’
+
the position in the file of the input frame, NAN if unknown
+
+
+
+
Additionally, these filters support an ‘enable’ command that can be used
+to re-define the expression.
+
+
Like any other filtering option, the ‘enable’ option follows the same
+rules.
+
+
For example, to enable a blur filter (smartblur) from 10 seconds to 3
+minutes, and a curves filter starting at 3 seconds:
+
When you configure your FFmpeg build, you can disable any of the
+existing filters using --disable-filters.
+The configure output will show the audio filters included in your
+build.
+
+
Below is a description of the currently available audio filters.
+
The filter accepts a string of the form:
+"sample_format:channel_layout".
+
+
sample_format specifies the sample format, and can be a string or the
+corresponding numeric value defined in ‘libavutil/samplefmt.h’. Use ’p’
+suffix for a planar sample format.
+
+
channel_layout specifies the channel layout, and can be a string
+or the corresponding number value defined in ‘libavutil/channel_layout.h’.
+
+
The special parameter "auto", signifies that the filter will
+automatically select the output format depending on the output filter.
+
Samples in delayed channel are filled with silence.
+
+
The filter accepts the following option:
+
+
+
‘delays’
+
Set list of delays in milliseconds for each channel separated by ’|’.
+At least one delay greater than 0 should be provided.
+Unused delays will be silently ignored. If number of given delays is
+smaller than number of channels all remaining channels will not be delayed.
+
+Delay first channel by 1.5 seconds, the third channel by 0.5 seconds and leave
+the second channel (and any other channels that may be present) unchanged.
+
Echoes are reflected sound and can occur naturally amongst mountains
+(and sometimes large buildings) when talking or shouting; digital echo
+effects emulate this behaviour and are often used to help fill out the
+sound of a single instrument or vocal. The time difference between the
+original signal and the reflection is the delay, and the
+loudness of the reflected signal is the decay.
+Multiple echoes can have different delays and decays.
+
+
A description of the accepted parameters follows.
+
+
+
‘in_gain’
+
Set input gain of reflected signal. Default is 0.6.
+
+
+
‘out_gain’
+
Set output gain of reflected signal. Default is 0.3.
+
+
+
‘delays’
+
Set list of time intervals in milliseconds between original signal and reflections
+separated by ’|’. Allowed range for each delay is (0 - 90000.0].
+Default is 1000.
+
+
+
‘decays’
+
Set list of loudnesses of reflected signals separated by ’|’.
+Allowed range for each decay is (0 - 1.0].
+Default is 0.5.
+
A description of the accepted parameters follows.
+
+
+
‘type, t’
+
Specify the effect type, can be either in for fade-in, or
+out for a fade-out effect. Default is in.
+
+
+
‘start_sample, ss’
+
Specify the number of the start sample for starting to apply the fade
+effect. Default is 0.
+
+
+
‘nb_samples, ns’
+
Specify the number of samples for which the fade effect has to last. At
+the end of the fade-in effect the output audio will have the same
+volume as the input audio, at the end of the fade-out transition
+the output audio will be silence. Default is 44100.
+
+
+
‘start_time, st’
+
Specify time for starting to apply the fade effect. Default is 0.
+The accepted syntax is:
+
[-]HH[:MM[:SS[.m...]]]
+[-]S+[.m...]
+
+
See also the function av_parse_time().
+If set this option is used instead of start_sample one.
+
+
+
‘duration, d’
+
Specify the duration for which the fade effect has to last. Default is 0.
+The accepted syntax is:
+
[-]HH[:MM[:SS[.m...]]]
+[-]S+[.m...]
+
+
See also the function av_parse_time().
+At the end of the fade-in effect the output audio will have the same
+volume as the input audio, at the end of the fade-out transition
+the output audio will be silence.
+If set this option is used instead of nb_samples one.
+
Apply a two-pole all-pass filter with central frequency (in Hz)
+frequency, and filter-width width.
+An all-pass filter changes the audio’s frequency to phase relationship
+without changing its frequency to amplitude relationship.
+
+
The filter accepts the following options:
+
+
+
‘frequency, f’
+
Set frequency in Hz.
+
+
+
‘width_type’
+
Set method to specify band-width of filter.
+
+
‘h’
+
Hz
+
+
‘q’
+
Q-Factor
+
+
‘o’
+
octave
+
+
‘s’
+
slope
+
+
+
+
+
‘width, w’
+
Specify the band-width of a filter in width_type units.
+
Merge two or more audio streams into a single multi-channel stream.
+
+
The filter accepts the following options:
+
+
+
‘inputs’
+
Set the number of inputs. Default is 2.
+
+
+
+
+
If the channel layouts of the inputs are disjoint, and therefore compatible,
+the channel layout of the output will be set accordingly and the channels
+will be reordered as necessary. If the channel layouts of the inputs are not
+disjoint, the output will have all the channels of the first input then all
+the channels of the second input, in that order, and the channel layout of
+the output will be the default value corresponding to the total number of
+channels.
+
+
For example, if the first input is in 2.1 (FL+FR+LF) and the second input
+is FC+BL+BR, then the output will be in 5.1, with the channels in the
+following order: a1, a2, b1, a3, b2, b3 (a1 is the first channel of the
+first input, b1 is the first channel of the second input).
+
+
On the other hand, if both input are in stereo, the output channels will be
+in the default order: a1, a2, b1, b2, and the channel layout will be
+arbitrarily set to 4.0, which may or may not be the expected value.
+
+
All inputs must have the same sample rate, and format.
+
+
If inputs do not have the same duration, the output will stop with the
+shortest.
+
Pad the end of a audio stream with silence, this can be used together with
+-shortest to extend audio streams to the same length as the video stream.
+
A phaser filter creates series of peaks and troughs in the frequency spectrum.
+The position of the peaks and troughs are modulated so that they vary over time, creating a sweeping effect.
+
+
A description of the accepted parameters follows.
+
Resample the input audio to the specified parameters, using the
+libswresample library. If none are specified then the filter will
+automatically convert between its input and output.
+
+
This filter is also able to stretch/squeeze the audio data to make it match
+the timestamps or to inject silence / cut out audio to make it match the
+timestamps, do a combination of both or do neither.
+
+
The filter accepts the syntax
+[sample_rate:]resampler_options, where sample_rate
+expresses a sample rate and resampler_options is a list of
+key=value pairs, separated by ":". See the
+ffmpeg-resampler manual for the complete list of supported options.
+
Set the number of samples per each output audio frame.
+
+
The last output packet may contain a different number of samples, as
+the filter will flush all the remaining samples when the input audio
+signal its end.
+
+
The filter accepts the following options:
+
+
+
‘nb_out_samples, n’
+
Set the number of frames per each output audio frame. The number is
+intended as the number of samples per each channel.
+Default value is 1024.
+
+
+
‘pad, p’
+
If set to 1, the filter will pad the last audio frame with zeroes, so
+that the last frame will contain the same number of samples as the
+previous ones. Default value is 1.
+
+
+
+
For example, to set the number of per-frame samples to 1234 and
+disable padding for the last frame, use:
+
Display time domain statistical information about the audio channels.
+Statistics are calculated and displayed for each audio channel and,
+where applicable, an overall figure is also given.
+
+
The filter accepts the following option:
+
+
‘length’
+
Short window length in seconds, used for peak and trough RMS measurement.
+Default is 0.05 (50 miliseconds). Allowed range is [0.1 - 10].
+
+
+
+
A description of each shown parameter follows:
+
+
+
‘DC offset’
+
Mean amplitude displacement from zero.
+
+
+
‘Min level’
+
Minimal sample level.
+
+
+
‘Max level’
+
Maximal sample level.
+
+
+
‘Peak level dB’
+
‘RMS level dB’
+
Standard peak and RMS level measured in dBFS.
+
+
+
‘RMS peak dB’
+
‘RMS trough dB’
+
Peak and trough values for RMS level measured over a short window.
+
+
+
‘Crest factor’
+
Standard ratio of peak to RMS level (note: not in dB).
+
+
+
‘Flat factor’
+
Flatness (i.e. consecutive samples with the same value) of the signal at its peak levels
+(i.e. either Min level or Max level).
+
+
+
‘Peak count’
+
Number of occasions (not the number of samples) that the signal attained either
+Min level or Max level.
+
Forward two audio streams and control the order the buffers are forwarded.
+
+
The filter accepts the following options:
+
+
+
‘expr, e’
+
Set the expression deciding which stream should be
+forwarded next: if the result is negative, the first stream is forwarded; if
+the result is positive or zero, the second stream is forwarded. It can use
+the following variables:
+
+
+
b1 b2
+
number of buffers forwarded so far on each stream
+
+
s1 s2
+
number of samples forwarded so far on each stream
+
+
t1 t2
+
current timestamp of each stream
+
+
+
+
The default value is t1-t2, which means to always forward the stream
+that has a smaller timestamp.
+
Synchronize audio data with timestamps by squeezing/stretching it and/or
+dropping samples/adding silence when needed.
+
+
This filter is not built by default, please use aresample to do squeezing/stretching.
+
+
The filter accepts the following named parameters:
+
+
‘compensate’
+
Enable stretching/squeezing the data to make it match the timestamps. Disabled
+by default. When disabled, time gaps are covered with silence.
+
+
+
‘min_delta’
+
Minimum difference between timestamps and audio data (in seconds) to trigger
+adding/dropping samples. Default value is 0.1. If you get non-perfect sync with
+this filter, try setting this parameter to 0.
+
+
+
‘max_comp’
+
Maximum compensation in samples per second. Relevant only with compensate=1.
+Default value 500.
+
+
+
‘first_pts’
+
Assume the first pts should be this value. The time base is 1 / sample rate.
+This allows for padding/trimming at the start of stream. By default, no
+assumption is made about the first frame’s expected pts, so no padding or
+trimming is done. For example, this could be set to 0 to pad the beginning with
+silence if an audio stream starts after the video stream or to trim any samples
+with a negative pts due to encoder delay.
+
The filter accepts exactly one parameter, the audio tempo. If not
+specified then the filter will assume nominal 1.0 tempo. Tempo must
+be in the [0.5, 2.0] range.
+
Trim the input so that the output contains one continuous subpart of the input.
+
+
This filter accepts the following options:
+
+
‘start’
+
Specify time of the start of the kept section, i.e. the audio sample
+with the timestamp start will be the first sample in the output.
+
+
+
‘end’
+
Specify time of the first audio sample that will be dropped, i.e. the
+audio sample immediately preceding the one with the timestamp end will be
+the last sample in the output.
+
+
+
‘start_pts’
+
Same as start, except this option sets the start timestamp in samples
+instead of seconds.
+
+
+
‘end_pts’
+
Same as end, except this option sets the end timestamp in samples instead
+of seconds.
+
+
+
‘duration’
+
Specify maximum duration of the output.
+
+
+
‘start_sample’
+
Number of the first sample that should be passed to output.
+
+
+
‘end_sample’
+
Number of the first sample that should be dropped.
+
+
+
+
‘start’, ‘end’, ‘duration’ are expressed as time
+duration specifications, check the "Time duration" section in the
+ffmpeg-utils manual.
+
+
Note that the first two sets of the start/end options and the ‘duration’
+option look at the frame timestamp, while the _sample options simply count the
+samples that pass through the filter. So start/end_pts and start/end_sample will
+give different results when the timestamps are wrong, inexact or do not start at
+zero. Also note that this filter does not modify the timestamps. If you wish
+that the output timestamps start at zero, insert the asetpts filter after the
+atrim filter.
+
+
If multiple start or end options are set, this filter tries to be greedy and
+keep all samples that match at least one of the specified constraints. To keep
+only the part that matches all the constraints at once, chain multiple atrim
+filters.
+
+
The defaults are such that all the input is kept. So it is possible to set e.g.
+just the end values to keep everything before the specified time.
+
+
Examples:
+
+
+drop everything except the second minute of input
+
Apply a two-pole Butterworth band-pass filter with central
+frequency frequency, and (3dB-point) band-width width.
+The csg option selects a constant skirt gain (peak gain = Q)
+instead of the default: constant 0dB peak gain.
+The filter roll off at 6dB per octave (20dB per decade).
+
+
The filter accepts the following options:
+
+
+
‘frequency, f’
+
Set the filter’s central frequency. Default is 3000.
+
+
+
‘csg’
+
Constant skirt gain if set to 1. Defaults to 0.
+
+
+
‘width_type’
+
Set method to specify band-width of filter.
+
+
‘h’
+
Hz
+
+
‘q’
+
Q-Factor
+
+
‘o’
+
octave
+
+
‘s’
+
slope
+
+
+
+
+
‘width, w’
+
Specify the band-width of a filter in width_type units.
+
Apply a two-pole Butterworth band-reject filter with central
+frequency frequency, and (3dB-point) band-width width.
+The filter roll off at 6dB per octave (20dB per decade).
+
+
The filter accepts the following options:
+
+
+
‘frequency, f’
+
Set the filter’s central frequency. Default is 3000.
+
+
+
‘width_type’
+
Set method to specify band-width of filter.
+
+
‘h’
+
Hz
+
+
‘q’
+
Q-Factor
+
+
‘o’
+
octave
+
+
‘s’
+
slope
+
+
+
+
+
‘width, w’
+
Specify the band-width of a filter in width_type units.
+
Boost or cut the bass (lower) frequencies of the audio using a two-pole
+shelving filter with a response similar to that of a standard
+hi-fi’s tone-controls. This is also known as shelving equalisation (EQ).
+
+
The filter accepts the following options:
+
+
+
‘gain, g’
+
Give the gain at 0 Hz. Its useful range is about -20
+(for a large cut) to +20 (for a large boost).
+Beware of clipping when using a positive gain.
+
+
+
‘frequency, f’
+
Set the filter’s central frequency and so can be used
+to extend or reduce the frequency range to be boosted or cut.
+The default value is 100 Hz.
+
+
+
‘width_type’
+
Set method to specify band-width of filter.
+
+
‘h’
+
Hz
+
+
‘q’
+
Q-Factor
+
+
‘o’
+
octave
+
+
‘s’
+
slope
+
+
+
+
+
‘width, w’
+
Determine how steep is the filter’s shelf transition.
+
Apply a biquad IIR filter with the given coefficients.
+Where b0, b1, b2 and a0, a1, a2
+are the numerator and denominator coefficients respectively.
+
This filter accepts the following named parameters:
+
+
‘channel_layout’
+
Channel layout of the output stream.
+
+
+
‘map’
+
Map channels from input to output. The argument is a ’|’-separated list of
+mappings, each in the in_channel-out_channel or
+in_channel form. in_channel can be either the name of the input
+channel (e.g. FL for front left) or its index in the input channel layout.
+out_channel is the name of the output channel or its index in the output
+channel layout. If out_channel is not given then it is implicitly an
+index, starting with zero and increasing by one for each mapping.
+
+
+
+
If no mapping is present, the filter will implicitly map input channels to
+output channels preserving index.
+
+
For example, assuming a 5.1+downmix input MOV file
+
Set list of times in seconds for each channel over which the instantaneous
+level of the input signal is averaged to determine its volume.
+‘attacks’ refers to increase of volume and ‘decays’ refers
+to decrease of volume.
+For most situations, the attack time (response to the audio getting louder)
+should be shorter than the decay time because the human ear is more sensitive
+to sudden loud audio than sudden soft audio.
+Typical value for attack is 0.3 seconds and for decay 0.8
+seconds.
+
+
+
‘points’
+
Set list of points for transfer function, specified in dB relative to maximum
+possible signal amplitude.
+Each key points list need to be defined using the following syntax:
+x0/y0 x1/y1 x2/y2 ....
+
+
The input values must be in strictly increasing order but the transfer
+function does not have to be monotonically rising.
+The point 0/0 is assumed but may be overridden (by 0/out-dBn).
+Typical values for the transfer function are -70/-70 -60/-20.
+
+
+
‘soft-knee’
+
Set amount for which the points at where adjacent line segments on the
+transfer function meet will be rounded. Defaults is 0.01.
+
+
+
‘gain’
+
Set additional gain in dB to be applied at all points on the transfer function
+and allows easy adjustment of the overall gain.
+Default is 0.
+
+
+
‘volume’
+
Set initial volume in dB to be assumed for each channel when filtering starts.
+This permits the user to supply a nominal level initially, so that,
+for example, a very large gain is not applied to initial signal levels before
+the companding has begun to operate. A typical value for audio which is
+initially quiet is -90 dB. Default is 0.
+
+
+
‘delay’
+
Set delay in seconds. Default is 0. The input audio
+is analysed immediately, but audio is delayed before being fed to the
+volume adjuster. Specifying a delay approximately equal to the attack/decay
+times allows the filter to effectively operate in predictive rather than
+reactive mode.
+
This filter adds ‘cues’ to 44.1kHz stereo (i.e. audio CD format) audio
+so that when listened to on headphones the stereo image is moved from
+inside your head (standard for headphones) to outside and in front of
+the listener (standard for speakers).
+
Apply a two-pole peaking equalisation (EQ) filter. With this
+filter, the signal-level at and around a selected frequency can
+be increased or decreased, whilst (unlike bandpass and bandreject
+filters) that at all other frequencies is unchanged.
+
+
In order to produce complex equalisation curves, this filter can
+be given several times, each with a different central frequency.
+
+
The filter accepts the following options:
+
+
+
‘frequency, f’
+
Set the filter’s central frequency in Hz.
+
+
+
‘width_type’
+
Set method to specify band-width of filter.
+
+
‘h’
+
Hz
+
+
‘q’
+
Q-Factor
+
+
‘o’
+
octave
+
+
‘s’
+
slope
+
+
+
+
+
‘width, w’
+
Specify the band-width of a filter in width_type units.
+
+
+
‘gain, g’
+
Set the required gain or attenuation in dB.
+Beware of clipping when using a positive gain.
+
Apply a high-pass filter with 3dB point frequency.
+The filter can be either single-pole, or double-pole (the default).
+The filter roll off at 6dB per pole per octave (20dB per pole per decade).
+
+
The filter accepts the following options:
+
+
+
‘frequency, f’
+
Set frequency in Hz. Default is 3000.
+
+
+
‘poles, p’
+
Set number of poles. Default is 2.
+
+
+
‘width_type’
+
Set method to specify band-width of filter.
+
+
‘h’
+
Hz
+
+
‘q’
+
Q-Factor
+
+
‘o’
+
octave
+
+
‘s’
+
slope
+
+
+
+
+
‘width, w’
+
Specify the band-width of a filter in width_type units.
+Applies only to double-pole filter.
+The default is 0.707q and gives a Butterworth response.
+
Join multiple input streams into one multi-channel stream.
+
+
The filter accepts the following named parameters:
+
+
‘inputs’
+
Number of input streams. Defaults to 2.
+
+
+
‘channel_layout’
+
Desired output channel layout. Defaults to stereo.
+
+
+
‘map’
+
Map channels from inputs to output. The argument is a ’|’-separated list of
+mappings, each in the input_idx.in_channel-out_channel
+form. input_idx is the 0-based index of the input stream. in_channel
+can be either the name of the input channel (e.g. FL for front left) or its
+index in the specified input stream. out_channel is the name of the output
+channel.
+
+
+
+
The filter will attempt to guess the mappings when those are not specified
+explicitly. It does so by first trying to find an unused matching input channel
+and if that fails it picks the first unused input channel.
+
+
E.g. to join 3 inputs (with properly set channel layouts)
+
To enable compilation of this filter you need to configure FFmpeg with
+--enable-ladspa.
+
+
+
‘file, f’
+
Specifies the name of LADSPA plugin library to load. If the environment
+variable LADSPA_PATH is defined, the LADSPA plugin is searched in
+each one of the directories specified by the colon separated list in
+LADSPA_PATH, otherwise in the standard LADSPA paths, which are in
+this order: ‘HOME/.ladspa/lib/’, ‘/usr/local/lib/ladspa/’,
+‘/usr/lib/ladspa/’.
+
+
+
‘plugin, p’
+
Specifies the plugin within the library. Some libraries contain only
+one plugin, but others contain many of them. If this is not set filter
+will list all available plugins within the specified library.
+
+
+
‘controls, c’
+
Set the ’|’ separated list of controls which are zero or more floating point
+values that determine the behavior of the loaded plugin (for example delay,
+threshold or gain).
+Controls need to be defined using the following syntax:
+c0=value0|c1=value1|c2=value2|..., where
+valuei is the value set on the i-th control.
+If ‘controls’ is set to help, all available controls and
+their valid ranges are printed.
+
+
+
‘sample_rate, s’
+
Specify the sample rate, default to 44100. Only used if plugin have
+zero inputs.
+
+
+
‘nb_samples, n’
+
Set the number of samples per channel per each output frame, default
+is 1024. Only used if plugin have zero inputs.
+
+
+
‘duration, d’
+
Set the minimum duration of the sourced audio. See the function
+av_parse_time() for the accepted format, also check the "Time duration"
+section in the ffmpeg-utils manual.
+Note that the resulting duration may be greater than the specified duration,
+as the generated audio is always cut at the end of a complete frame.
+If not specified, or the expressed duration is negative, the audio is
+supposed to be generated forever.
+Only used if plugin have zero inputs.
+
Apply a low-pass filter with 3dB point frequency.
+The filter can be either single-pole or double-pole (the default).
+The filter roll off at 6dB per pole per octave (20dB per pole per decade).
+
+
The filter accepts the following options:
+
+
+
‘frequency, f’
+
Set frequency in Hz. Default is 500.
+
+
+
‘poles, p’
+
Set number of poles. Default is 2.
+
+
+
‘width_type’
+
Set method to specify band-width of filter.
+
+
‘h’
+
Hz
+
+
‘q’
+
Q-Factor
+
+
‘o’
+
octave
+
+
‘s’
+
slope
+
+
+
+
+
‘width, w’
+
Specify the band-width of a filter in width_type units.
+Applies only to double-pole filter.
+The default is 0.707q and gives a Butterworth response.
+
Mix channels with specific gain levels. The filter accepts the output
+channel layout followed by a set of channels definitions.
+
+
This filter is also designed to remap efficiently the channels of an audio
+stream.
+
+
The filter accepts parameters of the form:
+"l:outdef:outdef:..."
+
+
+
‘l’
+
output channel layout or number of channels
+
+
+
‘outdef’
+
output channel specification, of the form:
+"out_name=[gain*]in_name[+[gain*]in_name...]"
+
+
+
‘out_name’
+
output channel to define, either a channel name (FL, FR, etc.) or a channel
+number (c0, c1, etc.)
+
+
+
‘gain’
+
multiplicative coefficient for the channel, 1 leaving the volume unchanged
+
+
+
‘in_name’
+
input channel to use, see out_name for details; it is not possible to mix
+named and numbered input channels
+
+
+
+
If the ‘=’ in a channel specification is replaced by ‘<’, then the gains for
+that specification will be renormalized so that the total is 1, thus
+avoiding clipping noise.
+
Note that ffmpeg integrates a default down-mix (and up-mix) system
+that should be preferred (see "-ac" option) unless you have very specific
+needs.
+
The channel remapping will be effective if, and only if:
+
+
+
gain coefficients are zeroes or ones,
+
only one input per channel output,
+
+
+
If all these conditions are satisfied, the filter will notify the user ("Pure
+channel mapping detected"), and use an optimized and lossless method to do the
+remapping.
+
+
For example, if you have a 5.1 source and want a stereo audio stream by
+dropping the extra channels:
+
pan="stereo: c0=FL : c1=FR"
+
+
+
Given the same source, you can also switch front left and front right channels
+and keep the input channel layout:
+
ReplayGain scanner filter. This filter takes an audio stream as an input and
+outputs it unchanged.
+At end of filtering it displays track_gain and track_peak.
+
This filter logs a message when it detects that the input audio volume is less
+or equal to a noise tolerance value for a duration greater or equal to the
+minimum detected noise duration.
+
+
The printed times and duration are expressed in seconds.
+
+
The filter accepts the following options:
+
+
+
‘duration, d’
+
Set silence duration until notification (default is 2 seconds).
+
+
+
‘noise, n’
+
Set noise tolerance. Can be specified in dB (in case "dB" is appended to the
+specified value) or amplitude ratio. Default is -60dB, or 0.001.
+
Boost or cut treble (upper) frequencies of the audio using a two-pole
+shelving filter with a response similar to that of a standard
+hi-fi’s tone-controls. This is also known as shelving equalisation (EQ).
+
+
The filter accepts the following options:
+
+
+
‘gain, g’
+
Give the gain at whichever is the lower of ~22 kHz and the
+Nyquist frequency. Its useful range is about -20 (for a large cut)
+to +20 (for a large boost). Beware of clipping when using a positive gain.
+
+
+
‘frequency, f’
+
Set the filter’s central frequency and so can be used
+to extend or reduce the frequency range to be boosted or cut.
+The default value is 3000 Hz.
+
+
+
‘width_type’
+
Set method to specify band-width of filter.
+
+
‘h’
+
Hz
+
+
‘q’
+
Q-Factor
+
+
‘o’
+
octave
+
+
‘s’
+
slope
+
+
+
+
+
‘width, w’
+
Determine how steep is the filter’s shelf transition.
+
The filter has no parameters. The input is not modified. Statistics about
+the volume will be printed in the log when the input stream end is reached.
+
+
In particular it will show the mean volume (root mean square), maximum
+volume (on a per-sample basis), and the beginning of a histogram of the
+registered volume values (from the maximum value to a cumulated 1/1000 of
+the samples).
+
+
All volumes are in decibels relative to the maximum PCM value.
+
Buffer audio frames, and make them available to the filter chain.
+
+
This source is mainly intended for a programmatic use, in particular
+through the interface defined in ‘libavfilter/asrc_abuffer.h’.
+
+
It accepts the following named parameters:
+
+
+
‘time_base’
+
Timebase which will be used for timestamps of submitted frames. It must be
+either a floating-point number or in numerator/denominator form.
+
+
+
‘sample_rate’
+
The sample rate of the incoming audio buffers.
+
+
+
‘sample_fmt’
+
The sample format of the incoming audio buffers.
+Either a sample format name or its corresponging integer representation from
+the enum AVSampleFormat in ‘libavutil/samplefmt.h’
+
+
+
‘channel_layout’
+
The channel layout of the incoming audio buffers.
+Either a channel layout name from channel_layout_map in
+‘libavutil/channel_layout.c’ or its corresponding integer representation
+from the AV_CH_LAYOUT_* macros in ‘libavutil/channel_layout.h’
+
+
+
‘channels’
+
The number of channels of the incoming audio buffers.
+If both channels and channel_layout are specified, then they
+must be consistent.
+
will instruct the source to accept planar 16bit signed stereo at 44100Hz.
+Since the sample format with name "s16p" corresponds to the number
+6 and the "stereo" channel layout corresponds to the value 0x3, this is
+equivalent to:
+
Generate an audio signal specified by an expression.
+
+
This source accepts in input one or more expressions (one for each
+channel), which are evaluated and used to generate a corresponding
+audio signal.
+
+
This source accepts the following options:
+
+
+
‘exprs’
+
Set the ’|’-separated expressions list for each separate channel. In case the
+‘channel_layout’ option is not specified, the selected channel layout
+depends on the number of provided expressions.
+
+
+
‘channel_layout, c’
+
Set the channel layout. The number of channels in the specified layout
+must be equal to the number of specified expressions.
+
+
+
‘duration, d’
+
Set the minimum duration of the sourced audio. See the function
+av_parse_time() for the accepted format.
+Note that the resulting duration may be greater than the specified
+duration, as the generated audio is always cut at the end of a
+complete frame.
+
+
If not specified, or the expressed duration is negative, the audio is
+supposed to be generated forever.
+
+
+
‘nb_samples, n’
+
Set the number of samples per channel per each output frame,
+default to 1024.
+
+
+
‘sample_rate, s’
+
Specify the sample rate, default to 44100.
+
+
+
+
Each expression in exprs can contain the following constants:
+
+
+
‘n’
+
number of the evaluated sample, starting from 0
+
+
+
‘t’
+
time of the evaluated sample expressed in seconds, starting from 0
+
Null audio source, return unprocessed audio frames. It is mainly useful
+as a template and to be employed in analysis / debugging tools, or as
+the source for filters which ignore the input data (for example the sox
+synth filter).
+
+
This source accepts the following options:
+
+
+
‘channel_layout, cl’
+
+
Specify the channel layout, and can be either an integer or a string
+representing a channel layout. The default value of channel_layout
+is "stereo".
+
+
Check the channel_layout_map definition in
+‘libavutil/channel_layout.c’ for the mapping between strings and
+channel layout values.
+
Buffer audio frames, and make them available to the end of filter chain.
+
+
This sink is mainly intended for programmatic use, in particular
+through the interface defined in ‘libavfilter/buffersink.h’
+or the options system.
+
+
It accepts a pointer to an AVABufferSinkContext structure, which
+defines the incoming buffers’ formats, to be passed as the opaque
+parameter to avfilter_init_filter for initialization.
+
When you configure your FFmpeg build, you can disable any of the
+existing filters using --disable-filters.
+The configure output will show the video filters included in your
+build.
+
+
Below is a description of the currently available video filters.
+
Add or replace the alpha component of the primary input with the
+grayscale value of a second input. This is intended for use with
+alphaextract to allow the transmission or storage of frame
+sequences that have alpha in a format that doesn’t support an alpha
+channel.
+
+
For example, to reconstruct full frames from a normal YUV-encoded video
+and a separate video created with alphaextract, you might use:
+
Since this filter is designed for reconstruction, it operates on frame
+sequences without considering timestamps, and terminates when either
+input reaches end of stream. This will cause problems if your encoding
+pipeline drops frames. If you’re trying to apply an image as an
+overlay to a video stream, consider the overlay filter instead.
+
Same as the subtitles filter, except that it doesn’t require libavcodec
+and libavformat to work. On the other hand, it is limited to ASS (Advanced
+Substation Alpha) subtitles files.
+
Compute the bounding box for the non-black pixels in the input frame
+luminance plane.
+
+
This filter computes the bounding box containing all the pixels with a
+luminance value greater than the minimum allowed value.
+The parameters describing the bounding box are printed on the filter
+log.
+
Detect video intervals that are (almost) completely black. Can be
+useful to detect chapter transitions, commercials, or invalid
+recordings. Output lines contains the time for the start, end and
+duration of the detected black interval expressed in seconds.
+
+
In order to display the output lines, you need to set the loglevel at
+least to the AV_LOG_INFO value.
+
+
The filter accepts the following options:
+
+
+
‘black_min_duration, d’
+
Set the minimum detected black duration expressed in seconds. It must
+be a non-negative floating point number.
+
+
Default value is 2.0.
+
+
+
‘picture_black_ratio_th, pic_th’
+
Set the threshold for considering a picture "black".
+Express the minimum value for the ratio:
+
nb_black_pixels / nb_pixels
+
+
+
for which a picture is considered black.
+Default value is 0.98.
+
+
+
‘pixel_black_th, pix_th’
+
Set the threshold for considering a pixel "black".
+
+
The threshold expresses the maximum pixel luminance value for which a
+pixel is considered "black". The provided value is scaled according to
+the following equation:
+
luminance_range_size and luminance_minimum_value depend on
+the input video format, the range is [0-255] for YUV full-range
+formats and [16-235] for YUV non full-range formats.
+
+
Default value is 0.10.
+
+
+
+
The following example sets the maximum pixel threshold to the minimum
+value, and detects only black intervals of 2 or more seconds:
+
Detect frames that are (almost) completely black. Can be useful to
+detect chapter transitions or commercials. Output lines consist of
+the frame number of the detected frame, the percentage of blackness,
+the position in the file if known or -1 and the timestamp in seconds.
+
+
In order to display the output lines, you need to set the loglevel at
+least to the AV_LOG_INFO value.
+
+
The filter accepts the following options:
+
+
+
‘amount’
+
Set the percentage of the pixels that have to be below the threshold, defaults
+to 98.
+
+
+
‘threshold, thresh’
+
Set the threshold below which a pixel value is considered black, defaults to
+32.
+
It takes two input streams and outputs one stream, the first input is the
+"top" layer and second input is "bottom" layer.
+Output terminates when shortest input terminates.
+
+
A description of the accepted options follows.
+
+
+
‘c0_mode’
+
‘c1_mode’
+
‘c2_mode’
+
‘c3_mode’
+
‘all_mode’
+
Set blend mode for specific pixel component or all pixel components in case
+of all_mode. Default value is normal.
+
+
Available values for component modes are:
+
+
‘addition’
+
‘and’
+
‘average’
+
‘burn’
+
‘darken’
+
‘difference’
+
‘divide’
+
‘dodge’
+
‘exclusion’
+
‘hardlight’
+
‘lighten’
+
‘multiply’
+
‘negation’
+
‘normal’
+
‘or’
+
‘overlay’
+
‘phoenix’
+
‘pinlight’
+
‘reflect’
+
‘screen’
+
‘softlight’
+
‘subtract’
+
‘vividlight’
+
‘xor’
+
+
+
+
‘c0_opacity’
+
‘c1_opacity’
+
‘c2_opacity’
+
‘c3_opacity’
+
‘all_opacity’
+
Set blend opacity for specific pixel component or all pixel components in case
+of all_opacity. Only used in combination with pixel component blend modes.
+
+
+
‘c0_expr’
+
‘c1_expr’
+
‘c2_expr’
+
‘c3_expr’
+
‘all_expr’
+
Set blend expression for specific pixel component or all pixel components in case
+of all_expr. Note that related mode options will be ignored if those are set.
+
+
The expressions can use the following variables:
+
+
+
‘N’
+
The sequential number of the filtered frame, starting from 0.
+
+
+
‘X’
+
‘Y’
+
the coordinates of the current sample
+
+
+
‘W’
+
‘H’
+
the width and height of currently filtered plane
+
+
+
‘SW’
+
‘SH’
+
Width and height scale depending on the currently filtered plane. It is the
+ratio between the corresponding luma plane number of pixels and the current
+plane ones. E.g. for YUV4:2:0 the values are 1,1 for the luma plane, and
+0.5,0.5 for chroma planes.
+
+
+
‘T’
+
Time of the current frame, expressed in seconds.
+
+
+
‘TOP, A’
+
Value of pixel component at current location for first video frame (top layer).
+
+
+
‘BOTTOM, B’
+
Value of pixel component at current location for second video frame (bottom layer).
+
+
+
+
+
‘shortest’
+
Force termination when the shortest input terminates. Default is 0.
+
+
‘repeatlast’
+
Continue applying the last bottom frame after the end of the stream. A value of
+0 disable the filter after the last frame of the bottom layer is reached.
+Default is 1.
+
Set an expression for the box radius in pixels used for blurring the
+corresponding input plane.
+
+
The radius value must be a non-negative number, and must not be
+greater than the value of the expression min(w,h)/2 for the
+luma and alpha planes, and of min(cw,ch)/2 for the chroma
+planes.
+
+
Default value for ‘luma_radius’ is "2". If not specified,
+‘chroma_radius’ and ‘alpha_radius’ default to the
+corresponding value set for ‘luma_radius’.
+
+
The expressions can contain the following constants:
+
+
‘w’
+
‘h’
+
the input width and height in pixels
+
+
+
‘cw’
+
‘ch’
+
the input chroma image width and height in pixels
+
+
+
‘hsub’
+
‘vsub’
+
horizontal and vertical chroma subsample values. For example for the
+pixel format "yuv422p" hsub is 2 and vsub is 1.
+
+
+
+
+
‘luma_power, lp’
+
‘chroma_power, cp’
+
‘alpha_power, ap’
+
Specify how many times the boxblur filter is applied to the
+corresponding plane.
+
+
Default value for ‘luma_power’ is 2. If not specified,
+‘chroma_power’ and ‘alpha_power’ default to the
+corresponding value set for ‘luma_power’.
+
Modify intensity of primary colors (red, green and blue) of input frames.
+
+
The filter allows an input frame to be adjusted in the shadows, midtones or highlights
+regions for the red-cyan, green-magenta or blue-yellow balance.
+
+
A positive adjustment value shifts the balance towards the primary color, a negative
+value towards the complementary color.
+
+
The filter accepts the following options:
+
+
+
‘rs’
+
‘gs’
+
‘bs’
+
Adjust red, green and blue shadows (darkest pixels).
+
+
+
‘rm’
+
‘gm’
+
‘bm’
+
Adjust red, green and blue midtones (medium pixels).
+
+
+
‘rh’
+
‘gh’
+
‘bh’
+
Adjust red, green and blue highlights (brightest pixels).
+
+
Allowed ranges for options are [-1.0, 1.0]. Defaults are 0.
+
Adjust video input frames by re-mixing color channels.
+
+
This filter modifies a color channel by adding the values associated to
+the other channels of the same pixels. For example if the value to
+modify is red, the output value will be:
+
red=red*rr + blue*rb + green*rg + alpha*ra
+
+
+
The filter accepts the following options:
+
+
+
‘rr’
+
‘rg’
+
‘rb’
+
‘ra’
+
Adjust contribution of input red, green, blue and alpha channels for output red channel.
+Default is 1 for rr, and 0 for rg, rb and ra.
+
+
+
‘gr’
+
‘gg’
+
‘gb’
+
‘ga’
+
Adjust contribution of input red, green, blue and alpha channels for output green channel.
+Default is 1 for gg, and 0 for gr, gb and ga.
+
+
+
‘br’
+
‘bg’
+
‘bb’
+
‘ba’
+
Adjust contribution of input red, green, blue and alpha channels for output blue channel.
+Default is 1 for bb, and 0 for br, bg and ba.
+
+
+
‘ar’
+
‘ag’
+
‘ab’
+
‘aa’
+
Adjust contribution of input red, green, blue and alpha channels for output alpha channel.
+Default is 1 for aa, and 0 for ar, ag and ab.
+
Width of the output video. It defaults to iw.
+This expression is evaluated only once during the filter
+configuration.
+
+
+
‘h, out_h’
+
Height of the output video. It defaults to ih.
+This expression is evaluated only once during the filter
+configuration.
+
+
+
‘x’
+
Horizontal position, in the input video, of the left edge of the output video.
+It defaults to (in_w-out_w)/2.
+This expression is evaluated per-frame.
+
+
+
‘y’
+
Vertical position, in the input video, of the top edge of the output video.
+It defaults to (in_h-out_h)/2.
+This expression is evaluated per-frame.
+
+
+
‘keep_aspect’
+
If set to 1 will force the output display aspect ratio
+to be the same of the input, by changing the output sample aspect
+ratio. It defaults to 0.
+
+
+
+
The out_w, out_h, x, y parameters are
+expressions containing the following constants:
+
+
+
‘x’
+
‘y’
+
the computed values for x and y. They are evaluated for
+each new frame.
+
+
+
‘in_w’
+
‘in_h’
+
the input width and height
+
+
+
‘iw’
+
‘ih’
+
same as in_w and in_h
+
+
+
‘out_w’
+
‘out_h’
+
the output (cropped) width and height
+
+
+
‘ow’
+
‘oh’
+
same as out_w and out_h
+
+
+
‘a’
+
same as iw / ih
+
+
+
‘sar’
+
input sample aspect ratio
+
+
+
‘dar’
+
input display aspect ratio, it is the same as (iw / ih) * sar
+
+
+
‘hsub’
+
‘vsub’
+
horizontal and vertical chroma subsample values. For example for the
+pixel format "yuv422p" hsub is 2 and vsub is 1.
+
+
+
‘n’
+
the number of input frame, starting from 0
+
+
+
‘pos’
+
the position in the file of the input frame, NAN if unknown
+
+
+
‘t’
+
timestamp expressed in seconds, NAN if the input timestamp is unknown
+
+
+
+
+
The expression for out_w may depend on the value of out_h,
+and the expression for out_h may depend on out_w, but they
+cannot depend on x and y, as x and y are
+evaluated after out_w and out_h.
+
+
The x and y parameters specify the expressions for the
+position of the top-left corner of the output (non-cropped) area. They
+are evaluated for each frame. If the evaluated value is not valid, it
+is approximated to the nearest valid value.
+
+
The expression for x may depend on y, and the expression
+for y may depend on x.
+
+Crop area with size 100x100 at position (12,34).
+
crop=100:100:12:34
+
+
+
Using named options, the example above becomes:
+
crop=w=100:h=100:x=12:y=34
+
+
+
+Crop the central input area with size 100x100:
+
crop=100:100
+
+
+
+Crop the central input area with size 2/3 of the input video:
+
crop=2/3*in_w:2/3*in_h
+
+
+
+Crop the input video central square:
+
crop=out_w=in_h
+crop=in_h
+
+
+
+Delimit the rectangle with the top-left corner placed at position
+100:100 and the right-bottom corner corresponding to the right-bottom
+corner of the input image:
+
crop=in_w-100:in_h-100:100:100
+
+
+
+Crop 10 pixels from the left and right borders, and 20 pixels from
+the top and bottom borders
+
crop=in_w-2*10:in_h-2*20
+
+
+
+Keep only the bottom right quarter of the input image:
+
Calculate necessary cropping parameters and prints the recommended
+parameters through the logging system. The detected dimensions
+correspond to the non-black area of the input video.
+
+
The filter accepts the following options:
+
+
+
‘limit’
+
Set higher black value threshold, which can be optionally specified
+from nothing (0) to everything (255). An intensity value greater
+to the set value is considered non-black. Default value is 24.
+
+
+
‘round’
+
Set the value for which the width/height should be divisible by. The
+offset is automatically adjusted to center the video. Use 2 to get
+only even dimensions (needed for 4:2:2 video). 16 is best when
+encoding to most video codecs. Default value is 16.
+
+
+
‘reset_count, reset’
+
Set the counter that determines after how many frames cropdetect will
+reset the previously detected largest video area and start over to
+detect the current optimal crop area. Default value is 0.
+
+
This can be useful when channel logos distort the video area. 0
+indicates never reset and return the largest area encountered during
+playback.
+
This filter is similar to the Adobe Photoshop and GIMP curves tools. Each
+component (red, green and blue) has its values defined by N key points
+tied from each other using a smooth curve. The x-axis represents the pixel
+values from the input frame, and the y-axis the new pixel values to be set for
+the output frame.
+
+
By default, a component curve is defined by the two points (0;0) and
+(1;1). This creates a straight line where each original pixel value is
+"adjusted" to its own value, which means no change to the image.
+
+
The filter allows you to redefine these two points and add some more. A new
+curve (using a natural cubic spline interpolation) will be define to pass
+smoothly through all these new coordinates. The new defined points needs to be
+strictly increasing over the x-axis, and their x and y values must
+be in the [0;1] interval. If the computed curves happened to go outside
+the vector spaces, the values will be clipped accordingly.
+
+
If there is no key point defined in x=0, the filter will automatically
+insert a (0;0) point. In the same way, if there is no key point defined
+in x=1, the filter will automatically insert a (1;1) point.
+
+
The filter accepts the following options:
+
+
+
‘preset’
+
Select one of the available color presets. This option can be used in addition
+to the ‘r’, ‘g’, ‘b’ parameters; in this case, the later
+options takes priority on the preset values.
+Available presets are:
+
+
‘none’
+
‘color_negative’
+
‘cross_process’
+
‘darker’
+
‘increase_contrast’
+
‘lighter’
+
‘linear_contrast’
+
‘medium_contrast’
+
‘negative’
+
‘strong_contrast’
+
‘vintage’
+
+
Default is none.
+
+
‘master, m’
+
Set the master key points. These points will define a second pass mapping. It
+is sometimes called a "luminance" or "value" mapping. It can be used with
+‘r’, ‘g’, ‘b’ or ‘all’ since it acts like a
+post-processing LUT.
+
+
‘red, r’
+
Set the key points for the red component.
+
+
‘green, g’
+
Set the key points for the green component.
+
+
‘blue, b’
+
Set the key points for the blue component.
+
+
‘all’
+
Set the key points for all components (not including master).
+Can be used in addition to the other key points component
+options. In this case, the unset component(s) will fallback on this
+‘all’ setting.
+
+
‘psfile’
+
Specify a Photoshop curves file (.asv) to import the settings from.
+
+
+
+
To avoid some filtergraph syntax conflicts, each key points list need to be
+defined using the following syntax: x0/y0 x1/y1 x2/y2 ....
+
Denoise frames using 2D DCT (frequency domain filtering).
+
+
This filter is not designed for real time and can be extremely slow.
+
+
The filter accepts the following options:
+
+
+
‘sigma, s’
+
Set the noise sigma constant.
+
+
This sigma defines a hard threshold of 3 * sigma; every DCT
+coefficient (absolute value) below this threshold with be dropped.
+
+
If you need a more advanced filtering, see ‘expr’.
+
+
Default is 0.
+
+
+
‘overlap’
+
Set number overlapping pixels for each block. Each block is of size
+16x16. Since the filter can be slow, you may want to reduce this value,
+at the cost of a less effective filter and the risk of various artefacts.
+
+
If the overlapping value doesn’t allow to process the whole input width or
+height, a warning will be displayed and according borders won’t be denoised.
+
+
Default value is 15.
+
+
+
‘expr, e’
+
Set the coefficient factor expression.
+
+
For each coefficient of a DCT block, this expression will be evaluated as a
+multiplier value for the coefficient.
+
+
If this is option is set, the ‘sigma’ option will be ignored.
+
+
The absolute value of the coefficient can be accessed through the c
+variable.
+
Set the number of frames from which one will be dropped. Setting this to
+N means one frame in every batch of N frames will be dropped.
+Default is 5.
+
+
+
‘dupthresh’
+
Set the threshold for duplicate detection. If the difference metric for a frame
+is less than or equal to this value, then it is declared as duplicate. Default
+is 1.1
+
+
+
‘scthresh’
+
Set scene change threshold. Default is 15.
+
+
+
‘blockx’
+
‘blocky’
+
Set the size of the x and y-axis blocks used during metric calculations.
+Larger blocks give better noise suppression, but also give worse detection of
+small movements. Must be a power of two. Default is 32.
+
+
+
‘ppsrc’
+
Mark main input as a pre-processed input and activate clean source input
+stream. This allows the input to be pre-processed with various filters to help
+the metrics calculation while keeping the frame selection lossless. When set to
+1, the first stream is for the pre-processed input, and the second
+stream is the clean source from where the kept frames are chosen. Default is
+0.
+
+
+
‘chroma’
+
Set whether or not chroma is considered in the metric calculations. Default is
+1.
+
Suppress a TV station logo by a simple interpolation of the surrounding
+pixels. Just set a rectangle covering the logo and watch it disappear
+(and sometimes something even uglier appear - your mileage may vary).
+
+
This filter accepts the following options:
+
+
‘x’
+
‘y’
+
Specify the top left corner coordinates of the logo. They must be
+specified.
+
+
+
‘w’
+
‘h’
+
Specify the width and height of the logo to clear. They must be
+specified.
+
+
+
‘band, t’
+
Specify the thickness of the fuzzy edge of the rectangle (added to
+w and h). The default value is 4.
+
+
+
‘show’
+
When set to 1, a green rectangle is drawn on the screen to simplify
+finding the right x, y, w, and h parameters.
+The default value is 0.
+
+
The rectangle is drawn on the outermost pixels which will be (partly)
+replaced with interpolated values. The values of the next pixels
+immediately outside this rectangle in each direction will be used to
+compute the interpolated pixel values inside the rectangle.
+
Attempt to fix small changes in horizontal and/or vertical shift. This
+filter helps remove camera shake from hand-holding a camera, bumping a
+tripod, moving on a vehicle, etc.
+
+
The filter accepts the following options:
+
+
+
‘x’
+
‘y’
+
‘w’
+
‘h’
+
Specify a rectangular area where to limit the search for motion
+vectors.
+If desired the search for motion vectors can be limited to a
+rectangular area of the frame defined by its top left corner, width
+and height. These parameters have the same meaning as the drawbox
+filter which can be used to visualise the position of the bounding
+box.
+
+
This is useful when simultaneous movement of subjects within the frame
+might be confused for camera motion by the motion vector search.
+
+
If any or all of x, y, w and h are set to -1
+then the full frame is used. This allows later options to be set
+without specifying the bounding box for the motion vector search.
+
+
Default - search the whole frame.
+
+
+
‘rx’
+
‘ry’
+
Specify the maximum extent of movement in x and y directions in the
+range 0-64 pixels. Default 16.
+
+
+
‘edge’
+
Specify how to generate pixels to fill blanks at the edge of the
+frame. Available values are:
+
+
‘blank, 0’
+
Fill zeroes at blank locations
+
+
‘original, 1’
+
Original image at blank locations
+
+
‘clamp, 2’
+
Extruded edge value at blank locations
+
+
‘mirror, 3’
+
Mirrored edge at blank locations
+
+
+
Default value is ‘mirror’.
+
+
+
‘blocksize’
+
Specify the blocksize to use for motion search. Range 4-128 pixels,
+default 8.
+
+
+
‘contrast’
+
Specify the contrast threshold for blocks. Only blocks with more than
+the specified contrast (difference between darkest and lightest
+pixels) will be considered. Range 1-255, default 125.
+
+
+
‘search’
+
Specify the search strategy. Available values are:
+
+
‘exhaustive, 0’
+
Set exhaustive search
+
+
‘less, 1’
+
Set less exhaustive search.
+
+
+
Default value is ‘exhaustive’.
+
+
+
‘filename’
+
If set then a detailed log of the motion search is written to the
+specified file.
+
+
+
‘opencl’
+
If set to 1, specify using OpenCL capabilities, only available if
+FFmpeg was configured with --enable-opencl. Default value is 0.
+
The expressions which specify the top left corner coordinates of the box. Default to 0.
+
+
+
‘width, w’
+
‘height, h’
+
The expressions which specify the width and height of the box, if 0 they are interpreted as
+the input width and height. Default to 0.
+
+
+
‘color, c’
+
Specify the color of the box to write. For the general syntax of this option,
+check the "Color" section in the ffmpeg-utils manual. If the special
+value invert is used, the box edge color is the same as the
+video with inverted luma.
+
+
+
‘thickness, t’
+
The expression which sets the thickness of the box edge. Default value is 3.
+
+
See below for the list of accepted constants.
+
+
+
+
The parameters for x, y, w and h and t are expressions containing the
+following constants:
+
+
+
‘dar’
+
The input display aspect ratio, it is the same as (w / h) * sar.
+
+
+
‘hsub’
+
‘vsub’
+
horizontal and vertical chroma subsample values. For example for the
+pixel format "yuv422p" hsub is 2 and vsub is 1.
+
+
+
‘in_h, ih’
+
‘in_w, iw’
+
The input width and height.
+
+
+
‘sar’
+
The input sample aspect ratio.
+
+
+
‘x’
+
‘y’
+
The x and y offset coordinates where the box is drawn.
+
+
+
‘w’
+
‘h’
+
The width and height of the drawn box.
+
+
+
‘t’
+
The thickness of the drawn box.
+
+
These constants allow the x, y, w, h and t expressions to refer to
+each other, so you may for example specify y=x/dar or h=w/dar.
+
The expressions which specify the coordinates of some point of grid intersection (meant to configure offset). Both default to 0.
+
+
+
‘width, w’
+
‘height, h’
+
The expressions which specify the width and height of the grid cell, if 0 they are interpreted as the
+input width and height, respectively, minus thickness, so image gets
+framed. Default to 0.
+
+
+
‘color, c’
+
Specify the color of the grid. For the general syntax of this option,
+check the "Color" section in the ffmpeg-utils manual. If the special
+value invert is used, the grid color is the same as the
+video with inverted luma.
+
+
+
‘thickness, t’
+
The expression which sets the thickness of the grid line. Default value is 1.
+
+
See below for the list of accepted constants.
+
+
+
+
The parameters for x, y, w and h and t are expressions containing the
+following constants:
+
+
+
‘dar’
+
The input display aspect ratio, it is the same as (w / h) * sar.
+
+
+
‘hsub’
+
‘vsub’
+
horizontal and vertical chroma subsample values. For example for the
+pixel format "yuv422p" hsub is 2 and vsub is 1.
+
+
+
‘in_h, ih’
+
‘in_w, iw’
+
The input grid cell width and height.
+
+
+
‘sar’
+
The input sample aspect ratio.
+
+
+
‘x’
+
‘y’
+
The x and y coordinates of some point of grid intersection (meant to configure offset).
+
+
+
‘w’
+
‘h’
+
The width and height of the drawn cell.
+
+
+
‘t’
+
The thickness of the drawn cell.
+
+
These constants allow the x, y, w, h and t expressions to refer to
+each other, so you may for example specify y=x/dar or h=w/dar.
+
The description of the accepted parameters follows.
+
+
+
‘box’
+
Used to draw a box around text using background color.
+Value should be either 1 (enable) or 0 (disable).
+The default value of box is 0.
+
+
+
‘boxcolor’
+
The color to be used for drawing box around text. For the syntax of this
+option, check the "Color" section in the ffmpeg-utils manual.
+
+
The default value of boxcolor is "white".
+
+
+
‘expansion’
+
Select how the text is expanded. Can be either none,
+strftime (deprecated) or
+normal (default). See the Text expansion section
+below for details.
+
+
+
‘fix_bounds’
+
If true, check and fix text coords to avoid clipping.
+
+
+
‘fontcolor’
+
The color to be used for drawing fonts. For the syntax of this option, check
+the "Color" section in the ffmpeg-utils manual.
+
+
The default value of fontcolor is "black".
+
+
+
‘fontfile’
+
The font file to be used for drawing text. Path must be included.
+This parameter is mandatory.
+
+
+
‘fontsize’
+
The font size to be used for drawing text.
+The default value of fontsize is 16.
+
+
+
‘ft_load_flags’
+
Flags to be used for loading the fonts.
+
+
The flags map the corresponding flags supported by libfreetype, and are
+a combination of the following values:
+
+
default
+
no_scale
+
no_hinting
+
render
+
no_bitmap
+
vertical_layout
+
force_autohint
+
crop_bitmap
+
pedantic
+
ignore_global_advance_width
+
no_recurse
+
ignore_transform
+
monochrome
+
linear_design
+
no_autohint
+
+
+
Default value is "render".
+
+
For more information consult the documentation for the FT_LOAD_*
+libfreetype flags.
+
+
+
‘shadowcolor’
+
The color to be used for drawing a shadow behind the drawn text. For the
+syntax of this option, check the "Color" section in the ffmpeg-utils manual.
+
+
The default value of shadowcolor is "black".
+
+
+
‘shadowx’
+
‘shadowy’
+
The x and y offsets for the text shadow position with respect to the
+position of the text. They can be either positive or negative
+values. Default value for both is "0".
+
+
+
‘start_number’
+
The starting frame number for the n/frame_num variable. The default value
+is "0".
+
+
+
‘tabsize’
+
The size in number of spaces to use for rendering the tab.
+Default value is 4.
+
+
+
‘timecode’
+
Set the initial timecode representation in "hh:mm:ss[:;.]ff"
+format. It can be used with or without text parameter. timecode_rate
+option must be specified.
+
+
+
‘timecode_rate, rate, r’
+
Set the timecode frame rate (timecode only).
+
+
+
‘text’
+
The text string to be drawn. The text must be a sequence of UTF-8
+encoded characters.
+This parameter is mandatory if no file is specified with the parameter
+textfile.
+
+
+
‘textfile’
+
A text file containing text to be drawn. The text must be a sequence
+of UTF-8 encoded characters.
+
+
This parameter is mandatory if no text string is specified with the
+parameter text.
+
+
If both text and textfile are specified, an error is thrown.
+
+
+
‘reload’
+
If set to 1, the textfile will be reloaded before each frame.
+Be sure to update it atomically, or it may be read partially, or even fail.
+
+
+
‘x’
+
‘y’
+
The expressions which specify the offsets where text will be drawn
+within the video frame. They are relative to the top/left border of the
+output image.
+
+
The default value of x and y is "0".
+
+
See below for the list of accepted constants and functions.
+
+
+
+
The parameters for x and y are expressions containing the
+following constants and functions:
+
+
+
‘dar’
+
input display aspect ratio, it is the same as (w / h) * sar
+
+
+
‘hsub’
+
‘vsub’
+
horizontal and vertical chroma subsample values. For example for the
+pixel format "yuv422p" hsub is 2 and vsub is 1.
+
+
+
‘line_h, lh’
+
the height of each text line
+
+
+
‘main_h, h, H’
+
the input height
+
+
+
‘main_w, w, W’
+
the input width
+
+
+
‘max_glyph_a, ascent’
+
the maximum distance from the baseline to the highest/upper grid
+coordinate used to place a glyph outline point, for all the rendered
+glyphs.
+It is a positive value, due to the grid’s orientation with the Y axis
+upwards.
+
+
+
‘max_glyph_d, descent’
+
the maximum distance from the baseline to the lowest grid coordinate
+used to place a glyph outline point, for all the rendered glyphs.
+This is a negative value, due to the grid’s orientation, with the Y axis
+upwards.
+
+
+
‘max_glyph_h’
+
maximum glyph height, that is the maximum height for all the glyphs
+contained in the rendered text, it is equivalent to ascent -
+descent.
+
+
+
‘max_glyph_w’
+
maximum glyph width, that is the maximum width for all the glyphs
+contained in the rendered text
+
+
+
‘n’
+
the number of input frame, starting from 0
+
+
+
‘rand(min, max)’
+
return a random number included between min and max
+
+
+
‘sar’
+
input sample aspect ratio
+
+
+
‘t’
+
timestamp expressed in seconds, NAN if the input timestamp is unknown
+
+
+
‘text_h, th’
+
the height of the rendered text
+
+
+
‘text_w, tw’
+
the width of the rendered text
+
+
+
‘x’
+
‘y’
+
the x and y offset coordinates where the text is drawn.
+
+
These parameters allow the x and y expressions to refer
+each other, so you can for example specify y=x/dar.
+
+
+
+
If libavfilter was built with --enable-fontconfig, then
+‘fontfile’ can be a fontconfig pattern or omitted.
+
If ‘expansion’ is set to strftime,
+the filter recognizes strftime() sequences in the provided text and
+expands them accordingly. Check the documentation of strftime(). This
+feature is deprecated.
+
+
If ‘expansion’ is set to none, the text is printed verbatim.
+
+
If ‘expansion’ is set to normal (which is the default),
+the following expansion mechanism is used.
+
+
The backslash character ’\’, followed by any character, always expands to
+the second character.
+
+
Sequence of the form %{...} are expanded. The text between the
+braces is a function name, possibly followed by arguments separated by ’:’.
+If the arguments contain special characters or delimiters (’:’ or ’}’),
+they should be escaped.
+
+
Note that they probably must also be escaped as the value for the
+‘text’ option in the filter argument string and as the filter
+argument in the filtergraph description, and possibly also for the shell,
+that makes up to four levels of escaping; using a text file avoids these
+problems.
+
+
The following functions are available:
+
+
+
expr, e
+
The expression evaluation result.
+
+
It must take one argument specifying the expression to be evaluated,
+which accepts the same constants and functions as the x and
+y values. Note that not all constants should be used, for
+example the text size is not known when evaluating the expression, so
+the constants text_w and text_h will have an undefined
+value.
+
+
+
gmtime
+
The time at which the filter is running, expressed in UTC.
+It can accept an argument: a strftime() format string.
+
+
+
localtime
+
The time at which the filter is running, expressed in the local time zone.
+It can accept an argument: a strftime() format string.
+
+
+
metadata
+
Frame metadata. It must take one argument specifying metadata key.
+
+
+
n, frame_num
+
The frame number, starting from 0.
+
+
+
pict_type
+
A 1 character description of the current picture type.
+
+
+
pts
+
The timestamp of the current frame, in seconds, with microsecond accuracy.
+
+Draw ’Test Text’ with font FreeSerif of size 24 at position x=100
+and y=50 (counting from the top-left corner of the screen), text is
+yellow with a red box around it. Both the text and the box have an
+opacity of 20%.
+
+
+Show a text line sliding from right to left in the last row of the video
+frame. The file ‘LONG_LINE’ is assumed to contain a single line
+with no newlines.
+
Detect and draw edges. The filter uses the Canny Edge Detection algorithm.
+
+
The filter accepts the following options:
+
+
+
‘low’
+
‘high’
+
Set low and high threshold values used by the Canny thresholding
+algorithm.
+
+
The high threshold selects the "strong" edge pixels, which are then
+connected through 8-connectivity with the "weak" edge pixels selected
+by the low threshold.
+
+
low and high threshold values must be choosen in the range
+[0,1], and low should be lesser or equal to high.
+
+
Default value for low is 20/255, and default value for high
+is 50/255.
+
The effect type – can be either "in" for fade-in, or "out" for a fade-out
+effect.
+Default is in.
+
+
+
‘start_frame, s’
+
Specify the number of the start frame for starting to apply the fade
+effect. Default is 0.
+
+
+
‘nb_frames, n’
+
The number of frames for which the fade effect has to last. At the end of the
+fade-in effect the output video will have the same intensity as the input video,
+at the end of the fade-out transition the output video will be completely black.
+Default is 25.
+
+
+
‘alpha’
+
If set to 1, fade only alpha channel, if one exists on the input.
+Default value is 0.
+
+
+
‘start_time, st’
+
Specify the timestamp (in seconds) of the frame to start to apply the fade
+effect. If both start_frame and start_time are specified, the fade will start at
+whichever comes last. Default is 0.
+
+
+
‘duration, d’
+
The number of seconds for which the fade effect has to last. At the end of the
+fade-in effect the output video will have the same intensity as the input video,
+at the end of the fade-out transition the output video will be completely black.
+If both duration and nb_frames are specified, duration is used. Default is 0.
+
Field matching filter for inverse telecine. It is meant to reconstruct the
+progressive frames from a telecined stream. The filter does not drop duplicated
+frames, so to achieve a complete inverse telecine fieldmatch needs to be
+followed by a decimation filter such as decimate in the filtergraph.
+
+
The separation of the field matching and the decimation is notably motivated by
+the possibility of inserting a de-interlacing filter fallback between the two.
+If the source has mixed telecined and real interlaced content,
+fieldmatch will not be able to match fields for the interlaced parts.
+But these remaining combed frames will be marked as interlaced, and thus can be
+de-interlaced by a later filter such as yadif before decimation.
+
+
In addition to the various configuration options, fieldmatch can take an
+optional second stream, activated through the ‘ppsrc’ option. If
+enabled, the frames reconstruction will be based on the fields and frames from
+this second stream. This allows the first input to be pre-processed in order to
+help the various algorithms of the filter, while keeping the output lossless
+(assuming the fields are matched properly). Typically, a field-aware denoiser,
+or brightness/contrast adjustments can help.
+
+
Note that this filter uses the same algorithms as TIVTC/TFM (AviSynth project)
+and VIVTC/VFM (VapourSynth project). The later is a light clone of TFM from
+which fieldmatch is based on. While the semantic and usage are very
+close, some behaviour and options names can differ.
+
+
The filter accepts the following options:
+
+
+
‘order’
+
Specify the assumed field order of the input stream. Available values are:
+
+
+
‘auto’
+
Auto detect parity (use FFmpeg’s internal parity value).
+
+
‘bff’
+
Assume bottom field first.
+
+
‘tff’
+
Assume top field first.
+
+
+
+
Note that it is sometimes recommended not to trust the parity announced by the
+stream.
+
+
Default value is auto.
+
+
+
‘mode’
+
Set the matching mode or strategy to use. ‘pc’ mode is the safest in the
+sense that it won’t risk creating jerkiness due to duplicate frames when
+possible, but if there are bad edits or blended fields it will end up
+outputting combed frames when a good match might actually exist. On the other
+hand, ‘pcn_ub’ mode is the most risky in terms of creating jerkiness,
+but will almost always find a good frame if there is one. The other values are
+all somewhere in between ‘pc’ and ‘pcn_ub’ in terms of risking
+jerkiness and creating duplicate frames versus finding good matches in sections
+with bad edits, orphaned fields, blended fields, etc.
+
+
More details about p/c/n/u/b are available in p/c/n/u/b meaning section.
+
+
Available values are:
+
+
+
‘pc’
+
2-way matching (p/c)
+
+
‘pc_n’
+
2-way matching, and trying 3rd match if still combed (p/c + n)
+
+
‘pc_u’
+
2-way matching, and trying 3rd match (same order) if still combed (p/c + u)
+
+
‘pc_n_ub’
+
2-way matching, trying 3rd match if still combed, and trying 4th/5th matches if
+still combed (p/c + n + u/b)
+
+
‘pcn’
+
3-way matching (p/c/n)
+
+
‘pcn_ub’
+
3-way matching, and trying 4th/5th matches if all 3 of the original matches are
+detected as combed (p/c/n + u/b)
+
+
+
+
The parenthesis at the end indicate the matches that would be used for that
+mode assuming ‘order’=tff (and ‘field’ on auto or
+top).
+
+
In terms of speed ‘pc’ mode is by far the fastest and ‘pcn_ub’ is
+the slowest.
+
+
Default value is pc_n.
+
+
+
‘ppsrc’
+
Mark the main input stream as a pre-processed input, and enable the secondary
+input stream as the clean source to pick the fields from. See the filter
+introduction for more details. It is similar to the ‘clip2’ feature from
+VFM/TFM.
+
+
Default value is 0 (disabled).
+
+
+
‘field’
+
Set the field to match from. It is recommended to set this to the same value as
+‘order’ unless you experience matching failures with that setting. In
+certain circumstances changing the field that is used to match from can have a
+large impact on matching performance. Available values are:
+
+
+
‘auto’
+
Automatic (same value as ‘order’).
+
+
‘bottom’
+
Match from the bottom field.
+
+
‘top’
+
Match from the top field.
+
+
+
+
Default value is auto.
+
+
+
‘mchroma’
+
Set whether or not chroma is included during the match comparisons. In most
+cases it is recommended to leave this enabled. You should set this to 0
+only if your clip has bad chroma problems such as heavy rainbowing or other
+artifacts. Setting this to 0 could also be used to speed things up at
+the cost of some accuracy.
+
+
Default value is 1.
+
+
+
‘y0’
+
‘y1’
+
These define an exclusion band which excludes the lines between ‘y0’ and
+‘y1’ from being included in the field matching decision. An exclusion
+band can be used to ignore subtitles, a logo, or other things that may
+interfere with the matching. ‘y0’ sets the starting scan line and
+‘y1’ sets the ending line; all lines in between ‘y0’ and
+‘y1’ (including ‘y0’ and ‘y1’) will be ignored. Setting
+‘y0’ and ‘y1’ to the same value will disable the feature.
+‘y0’ and ‘y1’ defaults to 0.
+
+
+
‘scthresh’
+
Set the scene change detection threshold as a percentage of maximum change on
+the luma plane. Good values are in the [8.0, 14.0] range. Scene change
+detection is only relevant in case ‘combmatch’=sc. The range for
+‘scthresh’ is [0.0, 100.0].
+
+
Default value is 12.0.
+
+
+
‘combmatch’
+
When ‘combatch’ is not none, fieldmatch will take into
+account the combed scores of matches when deciding what match to use as the
+final match. Available values are:
+
+
+
‘none’
+
No final matching based on combed scores.
+
+
‘sc’
+
Combed scores are only used when a scene change is detected.
+
+
‘full’
+
Use combed scores all the time.
+
+
+
+
Default is sc.
+
+
+
‘combdbg’
+
Force fieldmatch to calculate the combed metrics for certain matches and
+print them. This setting is known as ‘micout’ in TFM/VFM vocabulary.
+Available values are:
+
+
+
‘none’
+
No forced calculation.
+
+
‘pcn’
+
Force p/c/n calculations.
+
+
‘pcnub’
+
Force p/c/n/u/b calculations.
+
+
+
+
Default value is none.
+
+
+
‘cthresh’
+
This is the area combing threshold used for combed frame detection. This
+essentially controls how "strong" or "visible" combing must be to be detected.
+Larger values mean combing must be more visible and smaller values mean combing
+can be less visible or strong and still be detected. Valid settings are from
+-1 (every pixel will be detected as combed) to 255 (no pixel will
+be detected as combed). This is basically a pixel difference value. A good
+range is [8, 12].
+
+
Default value is 9.
+
+
+
‘chroma’
+
Sets whether or not chroma is considered in the combed frame decision. Only
+disable this if your source has chroma problems (rainbowing, etc.) that are
+causing problems for the combed frame detection with chroma enabled. Actually,
+using ‘chroma’=0 is usually more reliable, except for the case
+where there is chroma only combing in the source.
+
+
Default value is 0.
+
+
+
‘blockx’
+
‘blocky’
+
Respectively set the x-axis and y-axis size of the window used during combed
+frame detection. This has to do with the size of the area in which
+‘combpel’ pixels are required to be detected as combed for a frame to be
+declared combed. See the ‘combpel’ parameter description for more info.
+Possible values are any number that is a power of 2 starting at 4 and going up
+to 512.
+
+
Default value is 16.
+
+
+
‘combpel’
+
The number of combed pixels inside any of the ‘blocky’ by
+‘blockx’ size blocks on the frame for the frame to be detected as
+combed. While ‘cthresh’ controls how "visible" the combing must be, this
+setting controls "how much" combing there must be in any localized area (a
+window defined by the ‘blockx’ and ‘blocky’ settings) on the
+frame. Minimum value is 0 and maximum is blocky x blockx (at
+which point no frames will ever be detected as combed). This setting is known
+as ‘MI’ in TFM/VFM vocabulary.
+
The numbers correspond to the progressive frame the fields relate to. Here, the
+first two frames are progressive, the 3rd and 4th are combed, and so on.
+
+
When fieldmatch is configured to run a matching from bottom
+(‘field’=bottom) this is how this input stream get transformed:
+
+
Input stream:
+ T 1 2 2 3 4
+ B 1 2 3 4 4 <-- matching reference
+
+Matches: c c n n c
+
+Output stream:
+ T 1 2 3 4 4
+ B 1 2 3 4 4
+
+
+
As a result of the field matching, we can see that some frames get duplicated.
+To perform a complete inverse telecine, you need to rely on a decimation filter
+after this operation. See for instance the decimate filter.
+
+
The same operation now matching from top fields (‘field’=top)
+looks like this:
+
+
Input stream:
+ T 1 2 2 3 4 <-- matching reference
+ B 1 2 3 4 4
+
+Matches: c c p p c
+
+Output stream:
+ T 1 2 2 3 4
+ B 1 2 2 3 4
+
+
+
In these examples, we can see what p, c and n mean;
+basically, they refer to the frame and field of the opposite parity:
+
+
+
p matches the field of the opposite parity in the previous frame
+
c matches the field of the opposite parity in the current frame
+
n matches the field of the opposite parity in the next frame
+
The u and b matching are a bit special in the sense that they match
+from the opposite parity flag. In the following examples, we assume that we are
+currently matching the 2nd frame (Top:2, bottom:2). According to the match, a
+’x’ is placed above and below each matched fields.
+
+
With bottom matching (‘field’=bottom):
+
Match: c p n b u
+
+ x x x x x
+ Top 1 2 2 1 2 2 1 2 2 1 2 2 1 2 2
+ Bottom 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3
+ x x x x x
+
+Output frames:
+ 2 1 2 2 2
+ 2 2 2 1 3
+
+
+
With top matching (‘field’=top):
+
Match: c p n b u
+
+ x x x x x
+ Top 1 2 2 1 2 2 1 2 2 1 2 2 1 2 2
+ Bottom 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3
+ x x x x x
+
+Output frames:
+ 2 2 2 1 2
+ 2 1 3 2 2
+
Output field order. Valid values are tff for top field first or bff
+for bottom field first.
+
+
+
+
Default value is ‘tff’.
+
+
Transformation is achieved by shifting the picture content up or down
+by one line, and filling the remaining line with appropriate picture content.
+This method is consistent with most broadcast field order converters.
+
+
If the input video is not flagged as being interlaced, or it is already
+flagged as being of the required output field order then this filter does
+not alter the incoming video.
+
+
This filter is very useful when converting to or from PAL DV material,
+which is bottom field first.
+
Convert the input video to one of the specified pixel formats.
+Libavfilter will try to pick one that is supported for the input to
+the next filter.
+
+
This filter accepts the following parameters:
+
+
‘pix_fmts’
+
A ’|’-separated list of pixel format names, for example
+"pix_fmts=yuv420p|monow|rgb24".
+
Convert the video to specified constant frame rate by duplicating or dropping
+frames as necessary.
+
+
This filter accepts the following named parameters:
+
+
‘fps’
+
Desired output frame rate. The default is 25.
+
+
+
‘round’
+
Rounding method.
+
+
Possible values are:
+
+
‘zero’
+
zero round towards 0
+
+
‘inf’
+
round away from 0
+
+
‘down’
+
round towards -infinity
+
+
‘up’
+
round towards +infinity
+
+
‘near’
+
round to nearest
+
+
+
The default is near.
+
+
+
‘start_time’
+
Assume the first PTS should be the given value, in seconds. This allows for
+padding/trimming at the start of stream. By default, no assumption is made
+about the first frame’s expected PTS, so no padding or trimming is done.
+For example, this could be set to 0 to pad the beginning with duplicates of
+the first frame if a video stream starts after the audio stream or to trim any
+frames with a negative PTS.
+
+
+
+
+
Alternatively, the options can be specified as a flat string:
+fps[:round].
+
To enable compilation of this filter you need to install the frei0r
+header and configure FFmpeg with --enable-frei0r.
+
+
This filter accepts the following options:
+
+
+
‘filter_name’
+
The name to the frei0r effect to load. If the environment variable
+FREI0R_PATH is defined, the frei0r effect is searched in each one of the
+directories specified by the colon separated list in FREIOR_PATH,
+otherwise in the standard frei0r paths, which are in this order:
+‘HOME/.frei0r-1/lib/’, ‘/usr/local/lib/frei0r-1/’,
+‘/usr/lib/frei0r-1/’.
+
+
+
‘filter_params’
+
A ’|’-separated list of parameters to pass to the frei0r effect.
+
+
+
+
+
A frei0r effect parameter can be a boolean (whose values are specified
+with "y" and "n"), a double, a color (specified by the syntax
+R/G/B, (R, G, and B being float
+numbers from 0.0 to 1.0) or by a color description specified in the "Color"
+section in the ffmpeg-utils manual), a position (specified by the syntax X/Y,
+X and Y being float numbers) and a string.
+
+
The number and kind of parameters depend on the loaded effect. If an
+effect parameter is not specified the default value is set.
+
The colorspace is selected according to the specified options. If one
+of the ‘lum_expr’, ‘cb_expr’, or ‘cr_expr’
+options is specified, the filter will automatically select a YCbCr
+colorspace. If one of the ‘red_expr’, ‘green_expr’, or
+‘blue_expr’ options is specified, it will select an RGB
+colorspace.
+
+
If one of the chrominance expression is not defined, it falls back on the other
+one. If no alpha expression is specified it will evaluate to opaque value.
+If none of chrominance expressions are specified, they will evaluate
+to the luminance expression.
+
+
The expressions can use the following variables and functions:
+
+
+
‘N’
+
The sequential number of the filtered frame, starting from 0.
+
+
+
‘X’
+
‘Y’
+
The coordinates of the current sample.
+
+
+
‘W’
+
‘H’
+
The width and height of the image.
+
+
+
‘SW’
+
‘SH’
+
Width and height scale depending on the currently filtered plane. It is the
+ratio between the corresponding luma plane number of pixels and the current
+plane ones. E.g. for YUV4:2:0 the values are 1,1 for the luma plane, and
+0.5,0.5 for chroma planes.
+
+
+
‘T’
+
Time of the current frame, expressed in seconds.
+
+
+
‘p(x, y)’
+
Return the value of the pixel at location (x,y) of the current
+plane.
+
+
+
‘lum(x, y)’
+
Return the value of the pixel at location (x,y) of the luminance
+plane.
+
+
+
‘cb(x, y)’
+
Return the value of the pixel at location (x,y) of the
+blue-difference chroma plane. Return 0 if there is no such plane.
+
+
+
‘cr(x, y)’
+
Return the value of the pixel at location (x,y) of the
+red-difference chroma plane. Return 0 if there is no such plane.
+
+
+
‘r(x, y)’
+
‘g(x, y)’
+
‘b(x, y)’
+
Return the value of the pixel at location (x,y) of the
+red/green/blue component. Return 0 if there is no such component.
+
+
+
‘alpha(x, y)’
+
Return the value of the pixel at location (x,y) of the alpha
+plane. Return 0 if there is no such plane.
+
+
+
+
For functions, if x and y are outside the area, the value will be
+automatically clipped to the closer edge.
+
Fix the banding artifacts that are sometimes introduced into nearly flat
+regions by truncation to 8bit color depth.
+Interpolate the gradients that should go where the bands are, and
+dither them.
+
+
This filter is designed for playback only. Do not use it prior to
+lossy compression, because compression tends to lose the dither and
+bring back the bands.
+
+
This filter accepts the following options:
+
+
+
‘strength’
+
The maximum amount by which the filter will change any one pixel. Also the
+threshold for detecting nearly flat regions. Acceptable values range from .51 to
+64, default value is 1.2, out-of-range values will be clipped to the valid
+range.
+
+
+
‘radius’
+
The neighborhood to fit the gradient to. A larger radius makes for smoother
+gradients, but also prevents the filter from modifying the pixels near detailed
+regions. Acceptable values are 8-32, default value is 16, out-of-range values
+will be clipped to the valid range.
+
+
+
+
+
Alternatively, the options can be specified as a flat string:
+strength[:radius]
+
First input is the video stream to process, and second one is the Hald CLUT.
+The Hald CLUT input can be a simple picture or a complete video stream.
+
+
The filter accepts the following options:
+
+
+
‘shortest’
+
Force termination when the shortest input terminates. Default is 0.
+
+
‘repeatlast’
+
Continue applying the last CLUT after the end of the stream. A value of
+0 disable the filter after the last frame of the CLUT is reached.
+Default is 1.
+
+
+
+
haldclut also has the same interpolation options as lut3d (both
+filters share the same internals).
+
The Hald CLUT will be applied to the 10 first seconds (duration of
+‘clut.nut’), then the latest picture of that CLUT stream will be applied
+to the remaining frames of the mandelbrot stream.
+
A Hald CLUT is supposed to be a squared image of Level*Level*Level by
+Level*Level*Level pixels. For a given Hald CLUT, FFmpeg will select the
+biggest possible square starting at the top left of the picture. The remaining
+padding pixels (bottom or right) will be ignored. This area can be used to add
+a preview of the Hald CLUT.
+
+
Typically, the following generated Hald CLUT will be supported by the
+haldclut filter:
+
It contains the original and a preview of the effect of the CLUT: SMPTE color
+bars are displayed on the right-top, and below the same color bars processed by
+the color changes.
+
+
Then, the effect of this Hald CLUT can be visualized with:
+
This filter applies a global color histogram equalization on a
+per-frame basis.
+
+
It can be used to correct video that has a compressed range of pixel
+intensities. The filter redistributes the pixel intensities to
+equalize their distribution across the intensity range. It may be
+viewed as an "automatically adjusting contrast filter". This filter is
+useful only for correcting degraded or poorly captured source
+video.
+
+
The filter accepts the following options:
+
+
+
‘strength’
+
Determine the amount of equalization to be applied. As the strength
+is reduced, the distribution of pixel intensities more-and-more
+approaches that of the input frame. The value must be a float number
+in the range [0,1] and defaults to 0.200.
+
+
+
‘intensity’
+
Set the maximum intensity that can generated and scale the output
+values appropriately. The strength should be set as desired and then
+the intensity can be limited if needed to avoid washing-out. The value
+must be a float number in the range [0,1] and defaults to 0.210.
+
+
+
‘antibanding’
+
Set the antibanding level. If enabled the filter will randomly vary
+the luminance of output pixels by a small amount to avoid banding of
+the histogram. Possible values are none, weak or
+strong. It defaults to none.
+
Compute and draw a color distribution histogram for the input video.
+
+
The computed histogram is a representation of distribution of color components
+in an image.
+
+
The filter accepts the following options:
+
+
+
‘mode’
+
Set histogram mode.
+
+
It accepts the following values:
+
+
‘levels’
+
standard histogram that display color components distribution in an image.
+Displays color graph for each color component. Shows distribution
+of the Y, U, V, A or R, G, B components, depending on input format,
+in current frame. Bellow each graph is color component scale meter.
+
+
+
‘color’
+
chroma values in vectorscope, if brighter more such chroma values are
+distributed in an image.
+Displays chroma values (U/V color placement) in two dimensional graph
+(which is called a vectorscope). It can be used to read of the hue and
+saturation of the current frame. At a same time it is a histogram.
+The whiter a pixel in the vectorscope, the more pixels of the input frame
+correspond to that pixel (that is the more pixels have this chroma value).
+The V component is displayed on the horizontal (X) axis, with the leftmost
+side being V = 0 and the rightmost side being V = 255.
+The U component is displayed on the vertical (Y) axis, with the top
+representing U = 0 and the bottom representing U = 255.
+
+
The position of a white pixel in the graph corresponds to the chroma value
+of a pixel of the input clip. So the graph can be used to read of the
+hue (color flavor) and the saturation (the dominance of the hue in the color).
+As the hue of a color changes, it moves around the square. At the center of
+the square, the saturation is zero, which means that the corresponding pixel
+has no color. If you increase the amount of a specific color, while leaving
+the other colors unchanged, the saturation increases, and you move towards
+the edge of the square.
+
+
+
‘color2’
+
chroma values in vectorscope, similar as color but actual chroma values
+are displayed.
+
+
+
‘waveform’
+
per row/column color component graph. In row mode graph in the left side represents
+color component value 0 and right side represents value = 255. In column mode top
+side represents color component value = 0 and bottom side represents value = 255.
+
+
+
Default value is levels.
+
+
+
‘level_height’
+
Set height of level in levels. Default value is 200.
+Allowed range is [50, 2048].
+
+
+
‘scale_height’
+
Set height of color scale in levels. Default value is 12.
+Allowed range is [0, 40].
+
+
+
‘step’
+
Set step for waveform mode. Smaller values are useful to find out how much
+of same luminance values across input rows/columns are distributed.
+Default value is 10. Allowed range is [1, 255].
+
+
+
‘waveform_mode’
+
Set mode for waveform. Can be either row, or column.
+Default is row.
+
+
+
‘waveform_mirror’
+
Set mirroring mode for waveform. 0 means unmirrored, 1
+means mirrored. In mirrored mode, higher values will be represented on the left
+side for row mode and at the top for column mode. Default is
+0 (unmirrored).
+
+
+
‘display_mode’
+
Set display mode for waveform and levels.
+It accepts the following values:
+
+
‘parade’
+
Display separate graph for the color components side by side in
+row waveform mode or one below other in column waveform mode
+for waveform histogram mode. For levels histogram mode
+per color component graphs are placed one bellow other.
+
+
This display mode in waveform histogram mode makes it easy to spot
+color casts in the highlights and shadows of an image, by comparing the
+contours of the top and the bottom of each waveform.
+Since whites, grays, and blacks are characterized by
+exactly equal amounts of red, green, and blue, neutral areas of the
+picture should display three waveforms of roughly equal width/height.
+If not, the correction is easy to make by making adjustments to level the
+three waveforms.
+
+
+
‘overlay’
+
Presents information that’s identical to that in the parade, except
+that the graphs representing color components are superimposed directly
+over one another.
+
+
This display mode in waveform histogram mode can make it easier to spot
+the relative differences or similarities in overlapping areas of the color
+components that are supposed to be identical, such as neutral whites, grays,
+or blacks.
+
+
+
Default is parade.
+
+
+
‘levels_mode’
+
Set mode for levels. Can be either linear, or logarithmic.
+Default is linear.
+
High precision/quality 3d denoise filter. This filter aims to reduce
+image noise producing smooth images and making still images really
+still. It should enhance compressibility.
+
+
It accepts the following optional parameters:
+
+
+
‘luma_spatial’
+
a non-negative float number which specifies spatial luma strength,
+defaults to 4.0
+
+
+
‘chroma_spatial’
+
a non-negative float number which specifies spatial chroma strength,
+defaults to 3.0*luma_spatial/4.0
+
+
+
‘luma_tmp’
+
a float number which specifies luma temporal strength, defaults to
+6.0*luma_spatial/4.0
+
+
+
‘chroma_tmp’
+
a float number which specifies chroma temporal strength, defaults to
+luma_tmp*chroma_spatial/luma_spatial
+
This filter allows to process interlaced images fields without
+deinterlacing them. Deinterleaving splits the input frame into 2
+fields (so called half pictures). Odd lines are moved to the top
+half of the output image, even lines to the bottom half.
+You can process (filter) them independently and then re-interleave them.
+
+
The filter accepts the following options:
+
+
+
‘luma_mode, l’
+
‘chroma_mode, c’
+
‘alpha_mode, a’
+
Available values for luma_mode, chroma_mode and
+alpha_mode are:
+
+
+
‘none’
+
Do nothing.
+
+
+
‘deinterleave, d’
+
Deinterleave fields, placing one above the other.
+
+
+
‘interleave, i’
+
Interleave fields. Reverse the effect of deinterleaving.
+
+
+
Default value is none.
+
+
+
‘luma_swap, ls’
+
‘chroma_swap, cs’
+
‘alpha_swap, as’
+
Swap luma/chroma/alpha fields. Exchange even & odd lines. Default value is 0.
+
Simple interlacing filter from progressive contents. This interleaves upper (or
+lower) lines from odd frames with lower (or upper) lines from even frames,
+halving the frame rate and preserving image height.
+
+
Original Original New Frame
+ Frame 'j' Frame 'j+1' (tff)
+ ========== =========== ==================
+ Line 0 --------------------> Frame 'j' Line 0
+ Line 1 Line 1 ----> Frame 'j+1' Line 1
+ Line 2 ---------------------> Frame 'j' Line 2
+ Line 3 Line 3 ----> Frame 'j+1' Line 3
+ ... ... ...
+New Frame + 1 will be generated by Frame 'j+2' and Frame 'j+3' and so on
+
+
+
It accepts the following optional parameters:
+
+
+
‘scan’
+
determines whether the interlaced frame is taken from the even (tff - default)
+or odd (bff) lines of the progressive frame.
+
+
+
‘lowpass’
+
Enable (default) or disable the vertical lowpass filter to avoid twitter
+interlacing and reduce moire patterns.
+
Deinterlace input video by applying Donald Graft’s adaptive kernel
+deinterling. Work on interlaced parts of a video to produce
+progressive frames.
+
+
The description of the accepted parameters follows.
+
+
+
‘thresh’
+
Set the threshold which affects the filter’s tolerance when
+determining if a pixel line must be processed. It must be an integer
+in the range [0,255] and defaults to 10. A value of 0 will result in
+applying the process on every pixels.
+
+
+
‘map’
+
Paint pixels exceeding the threshold value to white if set to 1.
+Default is 0.
+
+
+
‘order’
+
Set the fields order. Swap fields if set to 1, leave fields alone if
+0. Default is 0.
+
+
+
‘sharp’
+
Enable additional sharpening if set to 1. Default is 0.
+
+
+
‘twoway’
+
Enable twoway sharpening if set to 1. Default is 0.
+
Compute a look-up table for binding each pixel component input value
+to an output value, and apply it to input video.
+
+
lutyuv applies a lookup table to a YUV input video, lutrgb
+to an RGB input video.
+
+
These filters accept the following options:
+
+
‘c0’
+
set first pixel component expression
+
+
‘c1’
+
set second pixel component expression
+
+
‘c2’
+
set third pixel component expression
+
+
‘c3’
+
set fourth pixel component expression, corresponds to the alpha component
+
+
+
‘r’
+
set red component expression
+
+
‘g’
+
set green component expression
+
+
‘b’
+
set blue component expression
+
+
‘a’
+
alpha component expression
+
+
+
‘y’
+
set Y/luminance component expression
+
+
‘u’
+
set U/Cb component expression
+
+
‘v’
+
set V/Cr component expression
+
+
+
+
Each of them specifies the expression to use for computing the lookup table for
+the corresponding pixel component values.
+
+
The exact component associated to each of the c* options depends on the
+format in input.
+
+
The lut filter requires either YUV or RGB pixel formats in input,
+lutrgb requires RGB pixel formats in input, and lutyuv requires YUV.
+
+
The expressions can contain the following constants and functions:
+
+
+
‘w’
+
‘h’
+
the input width and height
+
+
+
‘val’
+
input value for the pixel component
+
+
+
‘clipval’
+
the input value clipped in the minval-maxval range
+
+
+
‘maxval’
+
maximum value for the pixel component
+
+
+
‘minval’
+
minimum value for the pixel component
+
+
+
‘negval’
+
the negated value for the pixel component value clipped in the
+minval-maxval range , it corresponds to the expression
+"maxval-clipval+minval"
+
+
+
‘clip(val)’
+
the computed value in val clipped in the
+minval-maxval range
+
+
+
‘gammaval(gamma)’
+
the computed gamma correction value of the pixel component value
+clipped in the minval-maxval range, corresponds to the
+expression
+"pow((clipval-minval)/(maxval-minval)\,gamma)*(maxval-minval)+minval"
+
Merge color channel components from several video streams.
+
+
The filter accepts up to 4 input streams, and merge selected input
+planes to the output video.
+
+
This filter accepts the following options:
+
+
‘mapping’
+
Set input to output plane mapping. Default is 0.
+
+
The mappings is specified as a bitmap. It should be specified as a
+hexadecimal number in the form 0xAa[Bb[Cc[Dd]]]. ’Aa’ describes the
+mapping for the first plane of the output stream. ’A’ sets the number of
+the input stream to use (from 0 to 3), and ’a’ the plane number of the
+corresponding input to use (from 0 to 3). The rest of the mappings is
+similar, ’Bb’ describes the mapping for the output stream second
+plane, ’Cc’ describes the mapping for the output stream third plane and
+’Dd’ describes the mapping for the output stream fourth plane.
+
This filter provides a wrapper around some of the filters of
+MPlayer/MEncoder.
+
+
This wrapper is considered experimental. Some of the wrapped filters
+may not work properly and we may drop support for them, as they will
+be implemented natively into FFmpeg. Thus you should avoid
+depending on them when writing portable scripts.
+
+
The filter accepts the parameters:
+filter_name[:=]filter_params
+
+
filter_name is the name of a supported MPlayer filter,
+filter_params is a string containing the parameters accepted by
+the named filter.
+
+
The list of the currently supported filters follows:
+
+
eq2
+
eq
+
fspp
+
ilpack
+
pp7
+
softpulldown
+
uspp
+
+
+
The parameter syntax and behavior for the listed filters are the same
+of the corresponding MPlayer filters. For detailed instructions check
+the "VIDEO FILTERS" section in the MPlayer manual.
+
Drop frames that do not differ greatly from the previous frame in
+order to reduce frame rate.
+
+
The main use of this filter is for very-low-bitrate encoding
+(e.g. streaming over dialup modem), but it could in theory be used for
+fixing movies that were inverse-telecined incorrectly.
+
+
A description of the accepted options follows.
+
+
+
‘max’
+
Set the maximum number of consecutive frames which can be dropped (if
+positive), or the minimum interval between dropped frames (if
+negative). If the value is 0, the frame is dropped unregarding the
+number of previous sequentially dropped frames.
+
+
Default value is 0.
+
+
+
‘hi’
+
‘lo’
+
‘frac’
+
Set the dropping threshold values.
+
+
Values for ‘hi’ and ‘lo’ are for 8x8 pixel blocks and
+represent actual pixel value differences, so a threshold of 64
+corresponds to 1 unit of difference for each pixel, or the same spread
+out differently over the block.
+
+
A frame is a candidate for dropping if no 8x8 blocks differ by more
+than a threshold of ‘hi’, and if no more than ‘frac’ blocks (1
+meaning the whole image) differ by more than a threshold of ‘lo’.
+
+
Default value for ‘hi’ is 64*12, default value for ‘lo’ is
+64*5, and default value for ‘frac’ is 0.33.
+
Dilate an image by using a specific structuring element.
+This filter corresponds to the libopencv function cvDilate.
+
+
It accepts the parameters: struct_el|nb_iterations.
+
+
struct_el represents a structuring element, and has the syntax:
+colsxrows+anchor_xxanchor_y/shape
+
+
cols and rows represent the number of columns and rows of
+the structuring element, anchor_x and anchor_y the anchor
+point, and shape the shape for the structuring element, and
+can be one of the values "rect", "cross", "ellipse", "custom".
+
+
If the value for shape is "custom", it must be followed by a
+string of the form "=filename". The file with name
+filename is assumed to represent a binary image, with each
+printable character corresponding to a bright pixel. When a custom
+shape is used, cols and rows are ignored, the number
+or columns and rows of the read file are assumed instead.
+
+
The default value for struct_el is "3x3+0x0/rect".
+
+
nb_iterations specifies the number of times the transform is
+applied to the image, and defaults to 1.
+
+
Follow some example:
+
# use the default values
+ocv=dilate
+
+# dilate using a structuring element with a 5x5 cross, iterate two times
+ocv=filter_name=dilate:filter_params=5x5+2x2/cross|2
+
+# read the shape from the file diamond.shape, iterate two times
+# the file diamond.shape may contain a pattern of characters like this:
+# *
+# ***
+# *****
+# ***
+# *
+# the specified cols and rows are ignored (but not the anchor point coordinates)
+ocv=dilate:0x0+2x2/custom=diamond.shape|2
+
The filter takes the following parameters:
+type|param1|param2|param3|param4.
+
+
type is the type of smooth filter to apply, and can be one of
+the following values: "blur", "blur_no_scale", "median", "gaussian",
+"bilateral". The default value is "gaussian".
+
+
param1, param2, param3, and param4 are
+parameters whose meanings depend on smooth type. param1 and
+param2 accept integer positive values or 0, param3 and
+param4 accept float values.
+
+
The default value for param1 is 3, the default value for the
+other parameters is 0.
+
+
These parameters correspond to the parameters assigned to the
+libopencv function cvSmooth.
+
It takes two inputs and one output, the first input is the "main"
+video on which the second input is overlayed.
+
+
This filter accepts the following parameters:
+
+
A description of the accepted options follows.
+
+
+
‘x’
+
‘y’
+
Set the expression for the x and y coordinates of the overlayed video
+on the main video. Default value is "0" for both expressions. In case
+the expression is invalid, it is set to a huge value (meaning that the
+overlay will not be displayed within the output visible area).
+
+
+
‘eval’
+
Set when the expressions for ‘x’, and ‘y’ are evaluated.
+
+
It accepts the following values:
+
+
‘init’
+
only evaluate expressions once during the filter initialization or
+when a command is processed
+
+
+
‘frame’
+
evaluate expressions for each incoming frame
+
+
+
+
Default value is ‘frame’.
+
+
+
‘shortest’
+
If set to 1, force the output to terminate when the shortest input
+terminates. Default value is 0.
+
+
+
‘format’
+
Set the format for the output video.
+
+
It accepts the following values:
+
+
‘yuv420’
+
force YUV420 output
+
+
+
‘yuv444’
+
force YUV444 output
+
+
+
‘rgb’
+
force RGB output
+
+
+
+
Default value is ‘yuv420’.
+
+
+
‘rgb (deprecated)’
+
If set to 1, force the filter to accept inputs in the RGB
+color space. Default value is 0. This option is deprecated, use
+‘format’ instead.
+
+
+
‘repeatlast’
+
If set to 1, force the filter to draw the last overlay frame over the
+main input until the end of the stream. A value of 0 disables this
+behavior. Default value is 1.
+
+
+
+
The ‘x’, and ‘y’ expressions can contain the following
+parameters.
+
+
+
‘main_w, W’
+
‘main_h, H’
+
main input width and height
+
+
+
‘overlay_w, w’
+
‘overlay_h, h’
+
overlay input width and height
+
+
+
‘x’
+
‘y’
+
the computed values for x and y. They are evaluated for
+each new frame.
+
+
+
‘hsub’
+
‘vsub’
+
horizontal and vertical chroma subsample values of the output
+format. For example for the pixel format "yuv422p" hsub is 2 and
+vsub is 1.
+
+
+
‘n’
+
the number of input frame, starting from 0
+
+
+
‘pos’
+
the position in the file of the input frame, NAN if unknown
+
+
+
‘t’
+
timestamp expressed in seconds, NAN if the input timestamp is unknown
+
+
+
+
Note that the n, pos, t variables are available only
+when evaluation is done per frame, and will evaluate to NAN
+when ‘eval’ is set to ‘init’.
+
+
Be aware that frames are taken from each input video in timestamp
+order, hence, if their initial timestamps differ, it is a good idea
+to pass the two inputs through a setpts=PTS-STARTPTS filter to
+have them begin in the same zero timestamp, as it does the example for
+the movie filter.
+
+
You can chain together more overlays but you should test the
+efficiency of such approach.
+
Add paddings to the input image, and place the original input at the
+given coordinates x, y.
+
+
This filter accepts the following parameters:
+
+
+
‘width, w’
+
‘height, h’
+
Specify an expression for the size of the output image with the
+paddings added. If the value for width or height is 0, the
+corresponding input size is used for the output.
+
+
The width expression can reference the value set by the
+height expression, and vice versa.
+
+
The default value of width and height is 0.
+
+
+
‘x’
+
‘y’
+
Specify an expression for the offsets where to place the input image
+in the padded area with respect to the top/left border of the output
+image.
+
+
The x expression can reference the value set by the y
+expression, and vice versa.
+
+
The default value of x and y is 0.
+
+
+
‘color’
+
Specify the color of the padded area. For the syntax of this option,
+check the "Color" section in the ffmpeg-utils manual.
+
+
The default value of color is "black".
+
+
+
+
The value for the width, height, x, and y
+options are expressions containing the following constants:
+
+
+
‘in_w’
+
‘in_h’
+
the input video width and height
+
+
+
‘iw’
+
‘ih’
+
same as in_w and in_h
+
+
+
‘out_w’
+
‘out_h’
+
the output width and height, that is the size of the padded area as
+specified by the width and height expressions
+
+
+
‘ow’
+
‘oh’
+
same as out_w and out_h
+
+
+
‘x’
+
‘y’
+
x and y offsets as specified by the x and y
+expressions, or NAN if not yet specified
+
+
+
‘a’
+
same as iw / ih
+
+
+
‘sar’
+
input sample aspect ratio
+
+
+
‘dar’
+
input display aspect ratio, it is the same as (iw / ih) * sar
+
+
+
‘hsub’
+
‘vsub’
+
horizontal and vertical chroma subsample values. For example for the
+pixel format "yuv422p" hsub is 2 and vsub is 1.
+
+Add paddings with color "violet" to the input video. Output video
+size is 640x480, the top-left corner of the input video is placed at
+column 0, row 40:
+
pad=640:480:0:40:violet
+
+
+
The example above is equivalent to the following command:
+
pad=width=640:height=480:x=0:y=40:color=violet
+
+
+
+Pad the input to get an output with dimensions increased by 3/2,
+and put the input video at the center of the padded area:
+
pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
+
+
+
+Pad the input to get a squared output with size equal to the maximum
+value between the input width and height, and put the input video at
+the center of the padded area:
+
pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
+
+
+
+Pad the input to get a final w/h ratio of 16:9:
+
pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
+
+
+
+In case of anamorphic video, in order to set the output display aspect
+correctly, it is necessary to use sar in the expression,
+according to the relation:
+
(ih * X / ih) * sar = output_dar
+X = output_dar / sar
+
+
+
Thus the previous example needs to be modified to:
+
pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2"
+
+
+
+Double output size and put the input video in the bottom-right
+corner of the output padded area:
+
Correct perspective of video not recorded perpendicular to the screen.
+
+
A description of the accepted parameters follows.
+
+
+
‘x0’
+
‘y0’
+
‘x1’
+
‘y1’
+
‘x2’
+
‘y2’
+
‘x3’
+
‘y3’
+
Set coordinates expression for top left, top right, bottom left and bottom right corners.
+Default values are 0:0:W:0:0:H:W:H with which perspective will remain unchanged.
+
+
The expressions can use the following variables:
+
Delay interlaced video by one field time so that the field order changes.
+
+
The intended use is to fix PAL movies that have been captured with the
+opposite field order to the film-to-video transfer.
+
+
A description of the accepted parameters follows.
+
+
+
‘mode’
+
Set phase mode.
+
+
It accepts the following values:
+
+
‘t’
+
Capture field order top-first, transfer bottom-first.
+Filter will delay the bottom field.
+
+
+
‘b’
+
Capture field order bottom-first, transfer top-first.
+Filter will delay the top field.
+
+
+
‘p’
+
Capture and transfer with the same field order. This mode only exists
+for the documentation of the other options to refer to, but if you
+actually select it, the filter will faithfully do nothing.
+
+
+
‘a’
+
Capture field order determined automatically by field flags, transfer
+opposite.
+Filter selects among ‘t’ and ‘b’ modes on a frame by frame
+basis using field flags. If no field information is available,
+then this works just like ‘u’.
+
+
+
‘u’
+
Capture unknown or varying, transfer opposite.
+Filter selects among ‘t’ and ‘b’ on a frame by frame basis by
+analyzing the images and selecting the alternative that produces best
+match between the fields.
+
+
+
‘T’
+
Capture top-first, transfer unknown or varying.
+Filter selects among ‘t’ and ‘p’ using image analysis.
+
+
+
‘B’
+
Capture bottom-first, transfer unknown or varying.
+Filter selects among ‘b’ and ‘p’ using image analysis.
+
+
+
‘A’
+
Capture determined by field flags, transfer unknown or varying.
+Filter selects among ‘t’, ‘b’ and ‘p’ using field flags and
+image analysis. If no field information is available, then this works just
+like ‘U’. This is the default mode.
+
+
+
‘U’
+
Both capture and transfer unknown or varying.
+Filter selects among ‘t’, ‘b’ and ‘p’ using image analysis only.
+
Enable the specified chain of postprocessing subfilters using libpostproc. This
+library should be automatically selected with a GPL build (--enable-gpl).
+Subfilters must be separated by ’/’ and can be disabled by prepending a ’-’.
+Each subfilter and some options have a short and a long name that can be used
+interchangeably, i.e. dr/dering are the same.
+
+
The filters accept the following options:
+
+
+
‘subfilters’
+
Set postprocessing subfilters string.
+
+
+
+
All subfilters share common options to determine their scope:
+
+
+
‘a/autoq’
+
Honor the quality commands for this subfilter.
+
+
+
‘c/chrom’
+
Do chrominance filtering, too (default).
+
+
+
‘y/nochrom’
+
Do luminance filtering only (no chrominance).
+
+
+
‘n/noluma’
+
Do chrominance filtering only (no luminance).
+
+
+
+
These options can be appended after the subfilter name, separated by a ’|’.
+
+
Available subfilters are:
+
+
+
‘hb/hdeblock[|difference[|flatness]]’
+
Horizontal deblocking filter
+
+
‘difference’
+
Difference factor where higher values mean more deblocking (default: 32).
+
+
‘flatness’
+
Flatness threshold where lower values mean more deblocking (default: 39).
+
+
+
+
+
‘vb/vdeblock[|difference[|flatness]]’
+
Vertical deblocking filter
+
+
‘difference’
+
Difference factor where higher values mean more deblocking (default: 32).
+
+
‘flatness’
+
Flatness threshold where lower values mean more deblocking (default: 39).
+
+
+
+
+
‘ha/hadeblock[|difference[|flatness]]’
+
Accurate horizontal deblocking filter
+
+
‘difference’
+
Difference factor where higher values mean more deblocking (default: 32).
+
+
‘flatness’
+
Flatness threshold where lower values mean more deblocking (default: 39).
+
+
+
+
+
‘va/vadeblock[|difference[|flatness]]’
+
Accurate vertical deblocking filter
+
+
‘difference’
+
Difference factor where higher values mean more deblocking (default: 32).
+
+
‘flatness’
+
Flatness threshold where lower values mean more deblocking (default: 39).
+
+
+
+
+
+
The horizontal and vertical deblocking filters share the difference and
+flatness values so you cannot set different horizontal and vertical
+thresholds.
+
Obtain the average, maximum and minimum PSNR (Peak Signal to Noise
+Ratio) between two input videos.
+
+
This filter takes in input two input videos, the first input is
+considered the "main" source and is passed unchanged to the
+output. The second input is used as a "reference" video for computing
+the PSNR.
+
+
Both video inputs must have the same resolution and pixel format for
+this filter to work correctly. Also it assumes that both inputs
+have the same number of frames, which are compared one by one.
+
+
The obtained average PSNR is printed through the logging system.
+
+
The filter stores the accumulated MSE (mean squared error) of each
+frame, and at the end of the processing it is averaged across all frames
+equally, and the following formula is applied to obtain the PSNR:
+
+
PSNR = 10*log10(MAX^2/MSE)
+
+
+
Where MAX is the average of the maximum values of each component of the
+image.
+
+
The description of the accepted parameters follows.
+
+
+
‘stats_file, f’
+
If specified the filter will use the named file to save the PSNR of
+each individual frame.
+
+
+
+
The file printed if stats_file is selected, contains a sequence of
+key/value pairs of the form key:value for each compared
+couple of frames.
+
+
A description of each shown parameter follows:
+
+
+
‘n’
+
sequential number of the input frame, starting from 1
+
+
+
‘mse_avg’
+
Mean Square Error pixel-by-pixel average difference of the compared
+frames, averaged over all the image components.
+
+
+
‘mse_y, mse_u, mse_v, mse_r, mse_g, mse_g, mse_a’
+
Mean Square Error pixel-by-pixel average difference of the compared
+frames for the component specified by the suffix.
+
On this example the input file being processed is compared with the
+reference file ‘ref_movie.mpg’. The PSNR of each individual frame
+is stored in ‘stats.log’.
+
Pulldown reversal (inverse telecine) filter, capable of handling mixed
+hard-telecine, 24000/1001 fps progressive, and 30000/1001 fps progressive
+content.
+
+
The pullup filter is designed to take advantage of future context in making
+its decisions. This filter is stateless in the sense that it does not lock
+onto a pattern to follow, but it instead looks forward to the following
+fields in order to identify matches and rebuild progressive frames.
+
+
To produce content with an even framerate, insert the fps filter after
+pullup, use fps=24000/1001 if the input frame rate is 29.97fps,
+fps=24 for 30fps and the (rare) telecined 25fps input.
+
+
The filter accepts the following options:
+
+
+
‘jl’
+
‘jr’
+
‘jt’
+
‘jb’
+
These options set the amount of "junk" to ignore at the left, right, top, and
+bottom of the image, respectively. Left and right are in units of 8 pixels,
+while top and bottom are in units of 2 lines.
+The default is 8 pixels on each side.
+
+
+
‘sb’
+
Set the strict breaks. Setting this option to 1 will reduce the chances of
+filter generating an occasional mismatched frame, but it may also cause an
+excessive number of frames to be dropped during high motion sequences.
+Conversely, setting it to -1 will make filter match fields more easily.
+This may help processing of video where there is slight blurring between
+the fields, but may also cause there to be interlaced frames in the output.
+Default value is 0.
+
+
+
‘mp’
+
Set the metric plane to use. It accepts the following values:
+
+
‘l’
+
Use luma plane.
+
+
+
‘u’
+
Use chroma blue plane.
+
+
+
‘v’
+
Use chroma red plane.
+
+
+
+
This option may be set to use chroma plane instead of the default luma plane
+for doing filter’s computations. This may improve accuracy on very clean
+source material, but more likely will decrease accuracy, especially if there
+is chroma noise (rainbow effect) or any grayscale video.
+The main purpose of setting ‘mp’ to a chroma plane is to reduce CPU
+load and make pullup usable in realtime on slow machines.
+
+
+
+
For best results (without duplicated frames in the output file) it is
+necessary to change the output frame rate. For example, to inverse
+telecine NTSC input:
+
Suppress a TV station logo, using an image file to determine which
+pixels comprise the logo. It works by filling in the pixels that
+comprise the logo with neighboring pixels.
+
+
The filter accepts the following options:
+
+
+
‘filename, f’
+
Set the filter bitmap file, which can be any image format supported by
+libavformat. The width and height of the image file must match those of the
+video stream being processed.
+
+
+
+
Pixels in the provided bitmap image with a value of zero are not
+considered part of the logo, non-zero pixels are considered part of
+the logo. If you use white (255) for the logo and black (0) for the
+rest, you will be safe. For making the filter bitmap, it is
+recommended to take a screen capture of a black frame with the logo
+visible, and then using a threshold filter followed by the erode
+filter once or twice.
+
+
If needed, little splotches can be fixed manually. Remember that if
+logo pixels are not covered, the filter quality will be much
+reduced. Marking too many pixels as part of the logo does not hurt as
+much, but it will increase the amount of blurring needed to cover over
+the image and will destroy more information than necessary, and extra
+pixels will slow things down on a large logo.
+
Rotate video by an arbitrary angle expressed in radians.
+
+
The filter accepts the following options:
+
+
A description of the optional parameters follows.
+
+
‘angle, a’
+
Set an expression for the angle by which to rotate the input video
+clockwise, expressed as a number of radians. A negative value will
+result in a counter-clockwise rotation. By default it is set to "0".
+
+
This expression is evaluated for each frame.
+
+
+
‘out_w, ow’
+
Set the output width expression, default value is "iw".
+This expression is evaluated just once during configuration.
+
+
+
‘out_h, oh’
+
Set the output height expression, default value is "ih".
+This expression is evaluated just once during configuration.
+
+
+
‘bilinear’
+
Enable bilinear interpolation if set to 1, a value of 0 disables
+it. Default value is 1.
+
+
+
‘fillcolor, c’
+
Set the color used to fill the output area not covered by the rotated
+image. For the generalsyntax of this option, check the "Color" section in the
+ffmpeg-utils manual. If the special value "none" is selected then no
+background is printed (useful for example if the background is never shown).
+
+
Default value is "black".
+
+
+
+
The expressions for the angle and the output size can contain the
+following constants and functions:
+
+
+
‘n’
+
sequential number of the input frame, starting from 0. It is always NAN
+before the first frame is filtered.
+
+
+
‘t’
+
time in seconds of the input frame, it is set to 0 when the filter is
+configured. It is always NAN before the first frame is filtered.
+
+
+
‘hsub’
+
‘vsub’
+
horizontal and vertical chroma subsample values. For example for the
+pixel format "yuv422p" hsub is 2 and vsub is 1.
+
+
+
‘in_w, iw’
+
‘in_h, ih’
+
the input video width and heigth
+
+
+
‘out_w, ow’
+
‘out_h, oh’
+
the output width and heigth, that is the size of the padded area as
+specified by the width and height expressions
+
+
+
‘rotw(a)’
+
‘roth(a)’
+
the minimal width/height required for completely containing the input
+video rotated by a radians.
+
+
These are only available when computing the ‘out_w’ and
+‘out_h’ expressions.
+
Set luma blur filter strength, must be a value in range 0.1-4.0, default
+value is 1.0. A greater value will result in a more blurred image, and
+in slower processing.
+
+
+
‘luma_pre_filter_radius, lpfr’
+
Set luma pre-filter radius, must be a value in the 0.1-2.0 range, default
+value is 1.0.
+
+
+
‘luma_strength, ls’
+
Set luma maximum difference between pixels to still be considered, must
+be a value in the 0.1-100.0 range, default value is 1.0.
+
+
+
‘chroma_radius, cr’
+
Set chroma blur filter strength, must be a value in range 0.1-4.0. A
+greater value will result in a more blurred image, and in slower
+processing.
+
+
+
‘chroma_pre_filter_radius, cpfr’
+
Set chroma pre-filter radius, must be a value in the 0.1-2.0 range.
+
+
+
‘chroma_strength, cs’
+
Set chroma maximum difference between pixels to still be considered,
+must be a value in the 0.1-100.0 range.
+
+
+
+
Each chroma option value, if not explicitly specified, is set to the
+corresponding luma option value.
+
Scale (resize) the input video, using the libswscale library.
+
+
The scale filter forces the output display aspect ratio to be the same
+of the input, by changing the output sample aspect ratio.
+
+
If the input image format is different from the format requested by
+the next filter, the scale filter will convert the input to the
+requested format.
+
Set the output video dimension expression. Default value is the input
+dimension.
+
+
If the value is 0, the input width is used for the output.
+
+
If one of the values is -1, the scale filter will use a value that
+maintains the aspect ratio of the input image, calculated from the
+other specified dimension. If both of them are -1, the input size is
+used
+
+
See below for the list of accepted constants for use in the dimension
+expression.
+
+
+
‘interl’
+
Set the interlacing mode. It accepts the following values:
+
+
+
‘1’
+
Force interlaced aware scaling.
+
+
+
‘0’
+
Do not apply interlaced scaling.
+
+
+
‘-1’
+
Select interlaced aware scaling depending on whether the source frames
+are flagged as interlaced or not.
+
+
+
+
Default value is ‘0’.
+
+
+
‘flags’
+
Set libswscale scaling flags. See
+(ffmpeg-scaler)sws_flags for the
+complete list of values. If not explictly specified the filter applies
+the default flags.
+
+
+
‘size, s’
+
Set the video size. For the syntax of this option, check the "Video size"
+section in the ffmpeg-utils manual.
+
+
+
‘in_color_matrix’
+
‘out_color_matrix’
+
Set in/output YCbCr color space type.
+
+
This allows the autodetected value to be overridden as well as allows forcing
+a specific value used for the output and encoder.
+
+
If not specified, the color space type depends on the pixel format.
+
+
Possible values:
+
+
+
‘auto’
+
Choose automatically.
+
+
+
‘bt709’
+
Format conforming to International Telecommunication Union (ITU)
+Recommendation BT.709.
+
+
+
‘fcc’
+
Set color space conforming to the United States Federal Communications
+Commission (FCC) Code of Federal Regulations (CFR) Title 47 (2003) 73.682 (a).
+
+ITU-R Rec. BT.470-6 (1998) Systems B, B1, and G
+
+
+Society of Motion Picture and Television Engineers (SMPTE) ST 170:2004
+
+
+
+
+
‘smpte240m’
+
Set color space conforming to SMPTE ST 240:1999.
+
+
+
+
+
‘in_range’
+
‘out_range’
+
Set in/output YCbCr sample range.
+
+
This allows the autodetected value to be overridden as well as allows forcing
+a specific value used for the output and encoder. If not specified, the
+range depends on the pixel format. Possible values:
+
+
+
‘auto’
+
Choose automatically.
+
+
+
‘jpeg/full/pc’
+
Set full range (0-255 in case of 8-bit luma).
+
+
+
‘mpeg/tv’
+
Set "MPEG" range (16-235 in case of 8-bit luma).
+
+
+
+
+
‘force_original_aspect_ratio’
+
Enable decreasing or increasing output video width or height if necessary to
+keep the original aspect ratio. Possible values:
+
+
+
‘disable’
+
Scale the video as specified and disable this feature.
+
+
+
‘decrease’
+
The output video dimensions will automatically be decreased if needed.
+
+
+
‘increase’
+
The output video dimensions will automatically be increased if needed.
+
+
+
+
+
One useful instance of this option is that when you know a specific device’s
+maximum allowed resolution, you can use this to limit the output video to
+that, while retaining the aspect ratio. For example, device A allows
+1280x720 playback, and your video is 1920x800. Using this option (set it to
+decrease) and specifying 1280x720 to the command line makes the output
+1280x533.
+
+
Please note that this is a different thing than specifying -1 for ‘w’
+or ‘h’, you still need to specify the output resolution for this option
+to work.
+
+
+
+
+
The values of the ‘w’ and ‘h’ options are expressions
+containing the following constants:
+
The separatefields takes a frame-based video input and splits
+each frame into its components fields, producing a new half height clip
+with twice the frame rate and twice the frame count.
+
+
This filter use field-dominance information in frame to decide which
+of each pair of fields to place first in the output.
+If it gets it wrong use setfield filter before separatefields filter.
+
The setdar filter sets the Display Aspect Ratio for the filter
+output video.
+
+
This is done by changing the specified Sample (aka Pixel) Aspect
+Ratio, according to the following equation:
+
DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR
+
+
+
Keep in mind that the setdar filter does not modify the pixel
+dimensions of the video frame. Also the display aspect ratio set by
+this filter may be changed by later filters in the filterchain,
+e.g. in case of scaling or if another "setdar" or a "setsar" filter is
+applied.
+
+
The setsar filter sets the Sample (aka Pixel) Aspect Ratio for
+the filter output video.
+
+
Note that as a consequence of the application of this filter, the
+output display aspect ratio will change according to the equation
+above.
+
+
Keep in mind that the sample aspect ratio set by the setsar
+filter may be changed by later filters in the filterchain, e.g. if
+another "setsar" or a "setdar" filter is applied.
+
+
The filters accept the following options:
+
+
+
‘r, ratio, dar (setdar only), sar (setsar only)’
+
Set the aspect ratio used by the filter.
+
+
The parameter can be a floating point number string, an expression, or
+a string of the form num:den, where num and
+den are the numerator and denominator of the aspect ratio. If
+the parameter is not specified, it is assumed the value "0".
+In case the form "num:den" is used, the : character
+should be escaped.
+
+
+
‘max’
+
Set the maximum integer value to use for expressing numerator and
+denominator when reducing the expressed aspect ratio to a rational.
+Default value is 100.
+
The setfield filter marks the interlace type field for the
+output frames. It does not change the input frame, but only sets the
+corresponding property, which affects how the frame is treated by
+following filters (e.g. fieldorder or yadif).
+
Show a line containing various information for each input video frame.
+The input video is not modified.
+
+
The shown line contains a sequence of key/value pairs of the form
+key:value.
+
+
A description of each shown parameter follows:
+
+
+
‘n’
+
sequential number of the input frame, starting from 0
+
+
+
‘pts’
+
Presentation TimeStamp of the input frame, expressed as a number of
+time base units. The time base unit depends on the filter input pad.
+
+
+
‘pts_time’
+
Presentation TimeStamp of the input frame, expressed as a number of
+seconds
+
+
+
‘pos’
+
position of the frame in the input stream, -1 if this information in
+unavailable and/or meaningless (for example in case of synthetic video)
+
+
+
‘fmt’
+
pixel format name
+
+
+
‘sar’
+
sample aspect ratio of the input frame, expressed in the form
+num/den
+
+
+
‘s’
+
size of the input frame. For the syntax of this option, check the "Video size"
+section in the ffmpeg-utils manual.
+
+
+
‘i’
+
interlaced mode ("P" for "progressive", "T" for top field first, "B"
+for bottom field first)
+
+
+
‘iskey’
+
1 if the frame is a key frame, 0 otherwise
+
+
+
‘type’
+
picture type of the input frame ("I" for an I-frame, "P" for a
+P-frame, "B" for a B-frame, "?" for unknown type).
+Check also the documentation of the AVPictureType enum and of
+the av_get_picture_type_char function defined in
+‘libavutil/avutil.h’.
+
+
+
‘checksum’
+
Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame
+
+
+
‘plane_checksum’
+
Adler-32 checksum (printed in hexadecimal) of each plane of the input frame,
+expressed in the form "[c0c1c2c3]"
+
Blur the input video without impacting the outlines.
+
+
The filter accepts the following options:
+
+
+
‘luma_radius, lr’
+
Set the luma radius. The option value must be a float number in
+the range [0.1,5.0] that specifies the variance of the gaussian filter
+used to blur the image (slower if larger). Default value is 1.0.
+
+
+
‘luma_strength, ls’
+
Set the luma strength. The option value must be a float number
+in the range [-1.0,1.0] that configures the blurring. A value included
+in [0.0,1.0] will blur the image whereas a value included in
+[-1.0,0.0] will sharpen the image. Default value is 1.0.
+
+
+
‘luma_threshold, lt’
+
Set the luma threshold used as a coefficient to determine
+whether a pixel should be blurred or not. The option value must be an
+integer in the range [-30,30]. A value of 0 will filter all the image,
+a value included in [0,30] will filter flat areas and a value included
+in [-30,0] will filter edges. Default value is 0.
+
+
+
‘chroma_radius, cr’
+
Set the chroma radius. The option value must be a float number in
+the range [0.1,5.0] that specifies the variance of the gaussian filter
+used to blur the image (slower if larger). Default value is 1.0.
+
+
+
‘chroma_strength, cs’
+
Set the chroma strength. The option value must be a float number
+in the range [-1.0,1.0] that configures the blurring. A value included
+in [0.0,1.0] will blur the image whereas a value included in
+[-1.0,0.0] will sharpen the image. Default value is 1.0.
+
+
+
‘chroma_threshold, ct’
+
Set the chroma threshold used as a coefficient to determine
+whether a pixel should be blurred or not. The option value must be an
+integer in the range [-30,30]. A value of 0 will filter all the image,
+a value included in [0,30] will filter flat areas and a value included
+in [-30,0] will filter edges. Default value is 0.
+
+
+
+
If a chroma option is not explicitly set, the corresponding luma value
+is set.
+
Apply a simple postprocessing filter that compresses and decompresses the image
+at several (or - in the case of ‘quality’ level 6 - all) shifts
+and average the results.
+
+
The filter accepts the following options:
+
+
+
‘quality’
+
Set quality. This option defines the number of levels for averaging. It accepts
+an integer in the range 0-6. If set to 0, the filter will have no
+effect. A value of 6 means the higher quality. For each increment of
+that value the speed drops by a factor of approximately 2. Default value is
+3.
+
+
+
‘qp’
+
Force a constant quantization parameter. If not set, the filter will use the QP
+from the video stream (if available).
+
+
+
‘mode’
+
Set thresholding mode. Available modes are:
+
+
+
‘hard’
+
Set hard thresholding (default).
+
+
‘soft’
+
Set soft thresholding (better de-ringing effect, but likely blurrier).
+
+
+
+
+
‘use_bframe_qp’
+
Enable the use of the QP from the B-Frames if set to 1. Using this
+option may cause flicker since the B-Frames have often larger QP. Default is
+0 (not enabled).
+
Draw subtitles on top of input video using the libass library.
+
+
To enable compilation of this filter you need to configure FFmpeg with
+--enable-libass. This filter also requires a build with libavcodec and
+libavformat to convert the passed subtitles file to ASS (Advanced Substation
+Alpha) subtitles format.
+
+
The filter accepts the following options:
+
+
+
‘filename, f’
+
Set the filename of the subtitle file to read. It must be specified.
+
+
+
‘original_size’
+
Specify the size of the original video, the video for which the ASS file
+was composed. For the syntax of this option, check the "Video size" section in
+the ffmpeg-utils manual. Due to a misdesign in ASS aspect ratio arithmetic,
+this is necessary to correctly scale the fonts if the aspect ratio has been
+changed.
+
+
+
‘charenc’
+
Set subtitles input character encoding. subtitles filter only. Only
+useful if not UTF-8.
+
+
+
+
If the first key is not specified, it is assumed that the first value
+specifies the ‘filename’.
+
+
For example, to render the file ‘sub.srt’ on top of the input
+video, use the command:
+
Select the most representative frame in a given sequence of consecutive frames.
+
+
The filter accepts the following options:
+
+
+
‘n’
+
Set the frames batch size to analyze; in a set of n frames, the filter
+will pick one of them, and then handle the next batch of n frames until
+the end. Default is 100.
+
+
+
+
Since the filter keeps track of the whole frames sequence, a bigger n
+value will result in a higher memory usage, so a high value is not recommended.
+
Set the grid size (i.e. the number of lines and columns). For the syntax of
+this option, check the "Video size" section in the ffmpeg-utils manual.
+
+
+
‘nb_frames’
+
Set the maximum number of frames to render in the given area. It must be less
+than or equal to wxh. The default value is 0, meaning all
+the area will be used.
+
+
+
‘margin’
+
Set the outer border margin in pixels.
+
+
+
‘padding’
+
Set the inner border thickness (i.e. the number of pixels between frames). For
+more advanced padding options (such as having different values for the edges),
+refer to the pad video filter.
+
+
+
‘color’
+
Specify the color of the unused areaFor the syntax of this option, check the
+"Color" section in the ffmpeg-utils manual. The default value of color
+is "black".
+
Perform various types of temporal field interlacing.
+
+
Frames are counted starting from 1, so the first input frame is
+considered odd.
+
+
The filter accepts the following options:
+
+
+
‘mode’
+
Specify the mode of the interlacing. This option can also be specified
+as a value alone. See below for a list of values for this option.
+
+
Available values are:
+
+
+
‘merge, 0’
+
Move odd frames into the upper field, even into the lower field,
+generating a double height frame at half frame rate.
+
+
+
‘drop_odd, 1’
+
Only output even frames, odd frames are dropped, generating a frame with
+unchanged height at half frame rate.
+
+
+
‘drop_even, 2’
+
Only output odd frames, even frames are dropped, generating a frame with
+unchanged height at half frame rate.
+
+
+
‘pad, 3’
+
Expand each frame to full height, but pad alternate lines with black,
+generating a frame with double height at the same input frame rate.
+
+
+
‘interleave_top, 4’
+
Interleave the upper field from odd frames with the lower field from
+even frames, generating a frame with unchanged height at half frame rate.
+
+
+
‘interleave_bottom, 5’
+
Interleave the lower field from odd frames with the upper field from
+even frames, generating a frame with unchanged height at half frame rate.
+
+
+
‘interlacex2, 6’
+
Double frame rate with unchanged height. Frames are inserted each
+containing the second temporal field from the previous input frame and
+the first temporal field from the next input frame. This mode relies on
+the top_field_first flag. Useful for interlaced video displays with no
+field synchronisation.
+
+
+
+
Numeric values are deprecated but are accepted for backward
+compatibility reasons.
+
+
Default mode is merge.
+
+
+
‘flags’
+
Specify flags influencing the filter process.
+
+
Available value for flags is:
+
+
+
‘low_pass_filter, vlfp’
+
Enable vertical low-pass filtering in the filter.
+Vertical low-pass filtering is required when creating an interlaced
+destination from a progressive source which contains high-frequency
+vertical detail. Filtering will reduce interlace ’twitter’ and Moire
+patterning.
+
+
Vertical low-pass filtering can only be enabled for ‘mode’
+interleave_top and interleave_bottom.
+
Transpose rows with columns in the input video and optionally flip it.
+
+
This filter accepts the following options:
+
+
+
‘dir’
+
Specify the transposition direction.
+
+
Can assume the following values:
+
+
‘0, 4, cclock_flip’
+
Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
+
L.R L.l
+. . -> . .
+l.r R.r
+
+
+
+
‘1, 5, clock’
+
Rotate by 90 degrees clockwise, that is:
+
L.R l.L
+. . -> . .
+l.r r.R
+
+
+
+
‘2, 6, cclock’
+
Rotate by 90 degrees counterclockwise, that is:
+
L.R R.r
+. . -> . .
+l.r L.l
+
+
+
+
‘3, 7, clock_flip’
+
Rotate by 90 degrees clockwise and vertically flip, that is:
+
L.R r.R
+. . -> . .
+l.r l.L
+
+
+
+
+
For values between 4-7, the transposition is only done if the input
+video geometry is portrait and not landscape. These values are
+deprecated, the passthrough option should be used instead.
+
+
Numerical values are deprecated, and should be dropped in favor of
+symbolic constants.
+
+
+
‘passthrough’
+
Do not apply the transposition if the input geometry matches the one
+specified by the specified value. It accepts the following values:
+
Trim the input so that the output contains one continuous subpart of the input.
+
+
This filter accepts the following options:
+
+
‘start’
+
Specify time of the start of the kept section, i.e. the frame with the
+timestamp start will be the first frame in the output.
+
+
+
‘end’
+
Specify time of the first frame that will be dropped, i.e. the frame
+immediately preceding the one with the timestamp end will be the last
+frame in the output.
+
+
+
‘start_pts’
+
Same as start, except this option sets the start timestamp in timebase
+units instead of seconds.
+
+
+
‘end_pts’
+
Same as end, except this option sets the end timestamp in timebase units
+instead of seconds.
+
+
+
‘duration’
+
Specify maximum duration of the output.
+
+
+
‘start_frame’
+
Number of the first frame that should be passed to output.
+
+
+
‘end_frame’
+
Number of the first frame that should be dropped.
+
+
+
+
‘start’, ‘end’, ‘duration’ are expressed as time
+duration specifications, check the "Time duration" section in the
+ffmpeg-utils manual.
+
+
Note that the first two sets of the start/end options and the ‘duration’
+option look at the frame timestamp, while the _frame variants simply count the
+frames that pass through the filter. Also note that this filter does not modify
+the timestamps. If you wish that the output timestamps start at zero, insert a
+setpts filter after the trim filter.
+
+
If multiple start or end options are set, this filter tries to be greedy and
+keep all the frames that match at least one of the specified constraints. To keep
+only the part that matches all the constraints at once, chain multiple trim
+filters.
+
+
The defaults are such that all the input is kept. So it is possible to set e.g.
+just the end values to keep everything before the specified time.
+
+
Examples:
+
+
+drop everything except the second minute of input
+
Analyze video stabilization/deshaking. Perform pass 1 of 2, see
+vidstabtransform for pass 2.
+
+
This filter generates a file with relative translation and rotation
+transform information about subsequent frames, which is then used by
+the vidstabtransform filter.
+
+
To enable compilation of this filter you need to configure FFmpeg with
+--enable-libvidstab.
+
+
This filter accepts the following options:
+
+
+
‘result’
+
Set the path to the file used to write the transforms information.
+Default value is ‘transforms.trf’.
+
+
+
‘shakiness’
+
Set how shaky the video is and how quick the camera is. It accepts an
+integer in the range 1-10, a value of 1 means little shakiness, a
+value of 10 means strong shakiness. Default value is 5.
+
+
+
‘accuracy’
+
Set the accuracy of the detection process. It must be a value in the
+range 1-15. A value of 1 means low accuracy, a value of 15 means high
+accuracy. Default value is 9.
+
+
+
‘stepsize’
+
Set stepsize of the search process. The region around minimum is
+scanned with 1 pixel resolution. Default value is 6.
+
+
+
‘mincontrast’
+
Set minimum contrast. Below this value a local measurement field is
+discarded. Must be a floating point value in the range 0-1. Default
+value is 0.3.
+
+
+
‘tripod’
+
Set reference frame number for tripod mode.
+
+
If enabled, the motion of the frames is compared to a reference frame
+in the filtered stream, identified by the specified number. The idea
+is to compensate all movements in a more-or-less static scene and keep
+the camera view absolutely still.
+
+
If set to 0, it is disabled. The frames are counted starting from 1.
+
+
+
‘show’
+
Show fields and transforms in the resulting frames. It accepts an
+integer in the range 0-2. Default value is 0, which disables any
+visualization.
+
Video stabilization/deshaking: pass 2 of 2,
+see vidstabdetect for pass 1.
+
+
Read a file with transform information for each frame and
+apply/compensate them. Together with the vidstabdetect
+filter this can be used to deshake videos. See also
+http://public.hronopik.de/vid.stab. It is important to also use
+the unsharp filter, see below.
+
+
To enable compilation of this filter you need to configure FFmpeg with
+--enable-libvidstab.
+
+
This filter accepts the following options:
+
+
+
‘input’
+
path to the file used to read the transforms (default: ‘transforms.trf’)
+
+
+
‘smoothing’
+
number of frames (value*2 + 1) used for lowpass filtering the camera movements
+(default: 10). For example a number of 10 means that 21 frames are used
+(10 in the past and 10 in the future) to smoothen the motion in the
+video. A larger values leads to a smoother video, but limits the
+acceleration of the camera (pan/tilt movements).
+
+
+
‘maxshift’
+
maximal number of pixels to translate frames (default: -1 no limit)
+
+
+
‘maxangle’
+
maximal angle in radians (degree*PI/180) to rotate frames (default: -1
+no limit)
+
+
+
‘crop’
+
How to deal with borders that may be visible due to movement
+compensation. Available values are:
+
+
+
‘keep’
+
keep image information from previous frame (default)
+
+
‘black’
+
fill the border black
+
+
+
+
+
‘invert’
+
+
‘0’
+
keep transforms normal (default)
+
+
‘1’
+
invert transforms
+
+
+
+
+
‘relative’
+
consider transforms as
+
+
‘0’
+
absolute
+
+
‘1’
+
relative to previous frame (default)
+
+
+
+
+
‘zoom’
+
percentage to zoom (default: 0)
+
+
‘>0’
+
zoom in
+
+
‘<0’
+
zoom out
+
+
+
+
+
‘optzoom’
+
set optimal zooming to avoid borders
+
+
‘0’
+
disabled
+
+
‘1’
+
optimal static zoom value is determined (only very strong movements will lead to visible borders) (default)
+
+
‘2’
+
optimal adaptive zoom value is determined (no borders will be visible)
+
+
+
Note that the value given at zoom is added to the one calculated
+here.
+
+
+
‘interpol’
+
type of interpolation
+
+
Available values are:
+
+
‘no’
+
no interpolation
+
+
‘linear’
+
linear only horizontal
+
+
‘bilinear’
+
linear in both directions (default)
+
+
‘bicubic’
+
cubic in both directions (slow)
+
+
+
+
+
‘tripod’
+
virtual tripod mode means that the video is stabilized such that the
+camera stays stationary. Use also tripod option of
+vidstabdetect.
+
+
‘0’
+
off (default)
+
+
‘1’
+
virtual tripod mode: equivalent to relative=0:smoothing=0
+
Set lens angle expression as a number of radians.
+
+
The value is clipped in the [0,PI/2] range.
+
+
Default value: "PI/5"
+
+
+
‘x0’
+
‘y0’
+
Set center coordinates expressions. Respectively "w/2" and "h/2"
+by default.
+
+
+
‘mode’
+
Set forward/backward mode.
+
+
Available modes are:
+
+
‘forward’
+
The larger the distance from the central point, the darker the image becomes.
+
+
+
‘backward’
+
The larger the distance from the central point, the brighter the image becomes.
+This can be used to reverse a vignette effect, though there is no automatic
+detection to extract the lens ‘angle’ and other settings (yet). It can
+also be used to create a burning effect.
+
+
+
+
Default value is ‘forward’.
+
+
+
‘eval’
+
Set evaluation mode for the expressions (‘angle’, ‘x0’, ‘y0’).
+
+
It accepts the following values:
+
+
‘init’
+
Evaluate expressions only once during the filter initialization.
+
+
+
‘frame’
+
Evaluate expressions for each incoming frame. This is way slower than the
+‘init’ mode since it requires all the scalers to be re-computed, but it
+allows advanced dynamic expressions.
+
+
+
+
Default value is ‘init’.
+
+
+
‘dither’
+
Set dithering to reduce the circular banding effects. Default is 1
+(enabled).
+
+
+
‘aspect’
+
Set vignette aspect. This setting allows to adjust the shape of the vignette.
+Setting this value to the SAR of the input will make a rectangular vignetting
+following the dimensions of the video.
+
Deinterlace the input video ("w3fdif" stands for "Weston 3 Field
+Deinterlacing Filter").
+
+
Based on the process described by Martin Weston for BBC R&D, and
+implemented based on the de-interlace algorithm written by Jim
+Easterbrook for BBC R&D, the Weston 3 field deinterlacing filter
+uses filter coefficients calculated by BBC R&D.
+
+
There are two sets of filter coefficients, so called "simple":
+and "complex". Which set of filter coefficients is used can
+be set by passing an optional parameter:
+
+
+
‘filter’
+
Set the interlacing filter coefficients. Accepts one of the following values:
+
+
+
‘simple’
+
Simple filter coefficient set.
+
+
‘complex’
+
More-complex filter coefficient set.
+
+
+
Default value is ‘complex’.
+
+
+
‘deint’
+
Specify which frames to deinterlace. Accept one of the following values:
+
Buffer video frames, and make them available to the filter chain.
+
+
This source is mainly intended for a programmatic use, in particular
+through the interface defined in ‘libavfilter/vsrc_buffer.h’.
+
+
This source accepts the following options:
+
+
+
‘video_size’
+
Specify the size (width and height) of the buffered video frames. For the
+syntax of this option, check the "Video size" section in the ffmpeg-utils
+manual.
+
+
+
‘width’
+
Input video width.
+
+
+
‘height’
+
Input video height.
+
+
+
‘pix_fmt’
+
A string representing the pixel format of the buffered video frames.
+It may be a number corresponding to a pixel format, or a pixel format
+name.
+
+
+
‘time_base’
+
Specify the timebase assumed by the timestamps of the buffered frames.
+
+
+
‘frame_rate’
+
Specify the frame rate expected for the video stream.
+
+
+
‘pixel_aspect, sar’
+
Specify the sample aspect ratio assumed by the video frames.
+
+
+
‘sws_param’
+
Specify the optional parameters to be used for the scale filter which
+is automatically inserted when an input change is detected in the
+input size or format.
+
will instruct the source to accept video frames with size 320x240 and
+with format "yuv410p", assuming 1/24 as the timestamps timebase and
+square pixels (1:1 sample aspect ratio).
+Since the pixel format with name "yuv410p" corresponds to the number 6
+(check the enum AVPixelFormat definition in ‘libavutil/pixfmt.h’),
+this example corresponds to:
+
Create a pattern generated by an elementary cellular automaton.
+
+
The initial state of the cellular automaton can be defined through the
+‘filename’, and ‘pattern’ options. If such options are
+not specified an initial state is created randomly.
+
+
At each new frame a new row in the video is filled with the result of
+the cellular automaton next generation. The behavior when the whole
+frame is filled is defined by the ‘scroll’ option.
+
+
This source accepts the following options:
+
+
+
‘filename, f’
+
Read the initial cellular automaton state, i.e. the starting row, from
+the specified file.
+In the file, each non-whitespace character is considered an alive
+cell, a newline will terminate the row, and further characters in the
+file will be ignored.
+
+
+
‘pattern, p’
+
Read the initial cellular automaton state, i.e. the starting row, from
+the specified string.
+
+
Each non-whitespace character in the string is considered an alive
+cell, a newline will terminate the row, and further characters in the
+string will be ignored.
+
+
+
‘rate, r’
+
Set the video rate, that is the number of frames generated per second.
+Default is 25.
+
+
+
‘random_fill_ratio, ratio’
+
Set the random fill ratio for the initial cellular automaton row. It
+is a floating point number value ranging from 0 to 1, defaults to
+1/PHI.
+
+
This option is ignored when a file or a pattern is specified.
+
+
+
‘random_seed, seed’
+
Set the seed for filling randomly the initial row, must be an integer
+included between 0 and UINT32_MAX. If not specified, or if explicitly
+set to -1, the filter will try to use a good random seed on a best
+effort basis.
+
+
+
‘rule’
+
Set the cellular automaton rule, it is a number ranging from 0 to 255.
+Default value is 110.
+
+
+
‘size, s’
+
Set the size of the output video. For the syntax of this option, check
+the "Video size" section in the ffmpeg-utils manual.
+
+
If ‘filename’ or ‘pattern’ is specified, the size is set
+by default to the width of the specified initial state row, and the
+height is set to width * PHI.
+
+
If ‘size’ is set, it must contain the width of the specified
+pattern string, and the specified pattern will be centered in the
+larger row.
+
+
If a filename or a pattern string is not specified, the size value
+defaults to "320x518" (used for a randomly generated initial state).
+
+
+
‘scroll’
+
If set to 1, scroll the output upward when all the rows in the output
+have been already filled. If set to 0, the new generated row will be
+written over the top row just after the bottom row is filled.
+Defaults to 1.
+
+
+
‘start_full, full’
+
If set to 1, completely fill the output with generated rows before
+outputting the first frame.
+This is the default behavior, for disabling set the value to 0.
+
+
+
‘stitch’
+
If set to 1, stitch the left and right row edges together.
+This is the default behavior, for disabling set the value to 0.
+
Generate various test patterns, as generated by the MPlayer test filter.
+
+
The size of the generated video is fixed, and is 256x256.
+This source is useful in particular for testing encoding features.
+
+
This source accepts the following options:
+
+
+
‘rate, r’
+
Specify the frame rate of the sourced video, as the number of frames
+generated per second. It has to be a string in the format
+frame_rate_num/frame_rate_den, an integer number, a float
+number or a valid video frame rate abbreviation. The default value is
+"25".
+
+
+
‘duration, d’
+
Set the video duration of the sourced video. The accepted syntax is:
+
[-]HH:MM:SS[.m...]
+[-]S+[.m...]
+
+
See also the function av_parse_time().
+
+
If not specified, or the expressed duration is negative, the video is
+supposed to be generated forever.
+
+
+
‘test, t’
+
+
Set the number or the name of the test to perform. Supported tests are:
+
+
‘dc_luma’
+
‘dc_chroma’
+
‘freq_luma’
+
‘freq_chroma’
+
‘amp_luma’
+
‘amp_chroma’
+
‘cbp’
+
‘mv’
+
‘ring1’
+
‘ring2’
+
‘all’
+
+
+
Default value is "all", which will cycle through the list of all tests.
+
To enable compilation of this filter you need to install the frei0r
+header and configure FFmpeg with --enable-frei0r.
+
+
This source accepts the following options:
+
+
+
‘size’
+
The size of the video to generate. For the syntax of this option, check the
+"Video size" section in the ffmpeg-utils manual.
+
+
+
‘framerate’
+
Framerate of the generated video, may be a string of the form
+num/den or a frame rate abbreviation.
+
+
+
‘filter_name’
+
The name to the frei0r source to load. For more information regarding frei0r and
+how to set the parameters read the section frei0r in the description of
+the video filters.
+
+
+
‘filter_params’
+
A ’|’-separated list of parameters to pass to the frei0r source.
+
+
+
+
+
For example, to generate a frei0r partik0l source with size 200x200
+and frame rate 10 which is overlayed on the overlay filter main input:
+
This source is based on a generalization of John Conway’s life game.
+
+
The sourced input represents a life grid, each pixel represents a cell
+which can be in one of two possible states, alive or dead. Every cell
+interacts with its eight neighbours, which are the cells that are
+horizontally, vertically, or diagonally adjacent.
+
+
At each interaction the grid evolves according to the adopted rule,
+which specifies the number of neighbor alive cells which will make a
+cell stay alive or born. The ‘rule’ option allows to specify
+the rule to adopt.
+
+
This source accepts the following options:
+
+
+
‘filename, f’
+
Set the file from which to read the initial grid state. In the file,
+each non-whitespace character is considered an alive cell, and newline
+is used to delimit the end of each row.
+
+
If this option is not specified, the initial grid is generated
+randomly.
+
+
+
‘rate, r’
+
Set the video rate, that is the number of frames generated per second.
+Default is 25.
+
+
+
‘random_fill_ratio, ratio’
+
Set the random fill ratio for the initial random grid. It is a
+floating point number value ranging from 0 to 1, defaults to 1/PHI.
+It is ignored when a file is specified.
+
+
+
‘random_seed, seed’
+
Set the seed for filling the initial random grid, must be an integer
+included between 0 and UINT32_MAX. If not specified, or if explicitly
+set to -1, the filter will try to use a good random seed on a best
+effort basis.
+
+
+
‘rule’
+
Set the life rule.
+
+
A rule can be specified with a code of the kind "SNS/BNB",
+where NS and NB are sequences of numbers in the range 0-8,
+NS specifies the number of alive neighbor cells which make a
+live cell stay alive, and NB the number of alive neighbor cells
+which make a dead cell to become alive (i.e. to "born").
+"s" and "b" can be used in place of "S" and "B", respectively.
+
+
Alternatively a rule can be specified by an 18-bits integer. The 9
+high order bits are used to encode the next cell state if it is alive
+for each number of neighbor alive cells, the low order bits specify
+the rule for "borning" new cells. Higher order bits encode for an
+higher number of neighbor cells.
+For example the number 6153 = (12<<9)+9 specifies a stay alive
+rule of 12 and a born rule of 9, which corresponds to "S23/B03".
+
+
Default value is "S23/B3", which is the original Conway’s game of life
+rule, and will keep a cell alive if it has 2 or 3 neighbor alive
+cells, and will born a new cell if there are three alive cells around
+a dead cell.
+
+
+
‘size, s’
+
Set the size of the output video. For the syntax of this option, check the
+"Video size" section in the ffmpeg-utils manual.
+
+
If ‘filename’ is specified, the size is set by default to the
+same size of the input file. If ‘size’ is set, it must contain
+the size specified in the input file, and the initial grid defined in
+that file is centered in the larger resulting area.
+
+
If a filename is not specified, the size value defaults to "320x240"
+(used for a randomly generated initial grid).
+
+
+
‘stitch’
+
If set to 1, stitch the left and right grid edges together, and the
+top and bottom edges also. Defaults to 1.
+
+
+
‘mold’
+
Set cell mold speed. If set, a dead cell will go from ‘death_color’ to
+‘mold_color’ with a step of ‘mold’. ‘mold’ can have a
+value from 0 to 255.
+
+
+
‘life_color’
+
Set the color of living (or new born) cells.
+
+
+
‘death_color’
+
Set the color of dead cells. If ‘mold’ is set, this is the first color
+used to represent a dead cell.
+
+
+
‘mold_color’
+
Set mold color, for definitely dead and moldy cells.
+
+
For the syntax of these 3 color options, check the "Color" section in the
+ffmpeg-utils manual.
+
The color source provides an uniformly colored input.
+
+
The haldclutsrc source provides an identity Hald CLUT. See also
+haldclut filter.
+
+
The nullsrc source returns unprocessed video frames. It is
+mainly useful to be employed in analysis / debugging tools, or as the
+source for filters which ignore the input data.
+
+
The rgbtestsrc source generates an RGB test pattern useful for
+detecting RGB vs BGR issues. You should see a red, green and blue
+stripe from top to bottom.
+
+
The smptebars source generates a color bars pattern, based on
+the SMPTE Engineering Guideline EG 1-1990.
+
+
The smptehdbars source generates a color bars pattern, based on
+the SMPTE RP 219-2002.
+
+
The testsrc source generates a test video pattern, showing a
+color pattern, a scrolling gradient and a timestamp. This is mainly
+intended for testing purposes.
+
+
The sources accept the following options:
+
+
+
‘color, c’
+
Specify the color of the source, only available in the color
+source. For the syntax of this option, check the "Color" section in the
+ffmpeg-utils manual.
+
+
+
‘level’
+
Specify the level of the Hald CLUT, only available in the haldclutsrc
+source. A level of N generates a picture of N*N*N by N*N*N
+pixels to be used as identity matrix for 3D lookup tables. Each component is
+coded on a 1/(N*N) scale.
+
+
+
‘size, s’
+
Specify the size of the sourced video. For the syntax of this option, check the
+"Video size" section in the ffmpeg-utils manual. The default value is
+"320x240".
+
+
This option is not available with the haldclutsrc filter.
+
+
+
‘rate, r’
+
Specify the frame rate of the sourced video, as the number of frames
+generated per second. It has to be a string in the format
+frame_rate_num/frame_rate_den, an integer number, a float
+number or a valid video frame rate abbreviation. The default value is
+"25".
+
+
+
‘sar’
+
Set the sample aspect ratio of the sourced video.
+
+
+
‘duration, d’
+
Set the video duration of the sourced video. The accepted syntax is:
+
[-]HH[:MM[:SS[.m...]]]
+[-]S+[.m...]
+
+
See also the function av_parse_time().
+
+
If not specified, or the expressed duration is negative, the video is
+supposed to be generated forever.
+
+
+
‘decimals, n’
+
Set the number of decimals to show in the timestamp, only available in the
+testsrc source.
+
+
The displayed timestamp value will correspond to the original
+timestamp value multiplied by the power of 10 of the specified
+value. Default value is 0.
+
+
+
+
For example the following:
+
testsrc=duration=5.3:size=qcif:rate=10
+
+
+
will generate a video with a duration of 5.3 seconds, with size
+176x144 and a frame rate of 10 frames per second.
+
+
The following graph description will generate a red source
+with an opacity of 0.2, with size "qcif" and a frame rate of 10
+frames per second.
+
color=c=red@0.2:s=qcif:r=10
+
+
+
If the input content is to be ignored, nullsrc can be used. The
+following command generates noise in the luminance plane by employing
+the geq filter:
+
Buffer video frames, and make them available to the end of the filter
+graph.
+
+
This sink is mainly intended for a programmatic use, in particular
+through the interface defined in ‘libavfilter/buffersink.h’
+or the options system.
+
+
It accepts a pointer to an AVBufferSinkContext structure, which
+defines the incoming buffers’ formats, to be passed as the opaque
+parameter to avfilter_init_filter for initialization.
+
Convert input audio to a video output, representing the audio vector
+scope.
+
+
The filter is used to measure the difference between channels of stereo
+audio stream. A monoaural signal, consisting of identical left and right
+signal, results in straight vertical line. Any stereo separation is visible
+as a deviation from this line, creating a Lissajous figure.
+If the straight (or deviation from it) but horizontal line appears this
+indicates that the left and right channels are out of phase.
+
+
The filter accepts the following options:
+
+
+
‘mode, m’
+
Set the vectorscope mode.
+
+
Available values are:
+
+
‘lissajous’
+
Lissajous rotated by 45 degrees.
+
+
+
‘lissajous_xy’
+
Same as above but not rotated.
+
+
+
+
Default value is ‘lissajous’.
+
+
+
‘size, s’
+
Set the video size for the output. For the syntax of this option, check the "Video size"
+section in the ffmpeg-utils manual. Default value is 400x400.
+
+
+
‘rate, r’
+
Set the output frame rate. Default value is 25.
+
+
+
‘rc’
+
‘gc’
+
‘bc’
+
Specify the red, green and blue contrast. Default values are 40, 160 and 80.
+Allowed range is [0, 255].
+
+
+
‘rf’
+
‘gf’
+
‘bf’
+
Specify the red, green and blue fade. Default values are 15, 10 and 5.
+Allowed range is [0, 255].
+
+
+
‘zoom’
+
Set the zoom factor. Default value is 1. Allowed range is [1, 10].
+
Concatenate audio and video streams, joining them together one after the
+other.
+
+
The filter works on segments of synchronized video and audio streams. All
+segments must have the same number of streams of each type, and that will
+also be the number of streams at output.
+
+
The filter accepts the following options:
+
+
+
‘n’
+
Set the number of segments. Default is 2.
+
+
+
‘v’
+
Set the number of output video streams, that is also the number of video
+streams in each segment. Default is 1.
+
+
+
‘a’
+
Set the number of output audio streams, that is also the number of video
+streams in each segment. Default is 0.
+
+
+
‘unsafe’
+
Activate unsafe mode: do not fail if segments have a different format.
+
+
+
+
+
The filter has v+a outputs: first v video outputs, then
+a audio outputs.
+
+
There are nx(v+a) inputs: first the inputs for the first
+segment, in the same order as the outputs, then the inputs for the second
+segment, etc.
+
+
Related streams do not always have exactly the same duration, for various
+reasons including codec frame size or sloppy authoring. For that reason,
+related synchronized streams (e.g. a video and its audio track) should be
+concatenated at once. The concat filter will use the duration of the longest
+stream in each segment (except the last one), and if necessary pad shorter
+audio streams with silence.
+
+
For this filter to work correctly, all segments must start at timestamp 0.
+
+
All corresponding streams must have the same parameters in all segments; the
+filtering system will automatically select a common pixel format for video
+streams, and a common sample format, sample rate and channel layout for
+audio streams, but other settings, such as resolution, must be converted
+explicitly by the user.
+
+
Different frame rates are acceptable but will result in variable frame rate
+at output; be sure to configure the output file to handle it.
+
EBU R128 scanner filter. This filter takes an audio stream as input and outputs
+it unchanged. By default, it logs a message at a frequency of 10Hz with the
+Momentary loudness (identified by M), Short-term loudness (S),
+Integrated loudness (I) and Loudness Range (LRA).
+
+
The filter also has a video output (see the video option) with a real
+time graph to observe the loudness evolution. The graphic contains the logged
+message mentioned above, so it is not printed anymore when this option is set,
+unless the verbose logging is set. The main graphing area contains the
+short-term loudness (3 seconds of analysis), and the gauge on the right is for
+the momentary loudness (400 milliseconds).
+
Activate the video output. The audio stream is passed unchanged whether this
+option is set or no. The video stream will be the first output stream if
+activated. Default is 0.
+
+
+
‘size’
+
Set the video size. This option is for video only. For the syntax of this
+option, check the "Video size" section in the ffmpeg-utils manual. Default
+and minimum resolution is 640x480.
+
+
+
‘meter’
+
Set the EBU scale meter. Default is 9. Common values are 9 and
+18, respectively for EBU scale meter +9 and EBU scale meter +18. Any
+other integer value between this range is allowed.
+
+
+
‘metadata’
+
Set metadata injection. If set to 1, the audio input will be segmented
+into 100ms output frames, each of them containing various loudness information
+in metadata. All the metadata keys are prefixed with lavfi.r128..
+
+
Default is 0.
+
+
+
‘framelog’
+
Force the frame logging level.
+
+
Available values are:
+
+
‘info’
+
information logging level
+
+
‘verbose’
+
verbose logging level
+
+
+
+
By default, the logging level is set to info. If the ‘video’ or
+the ‘metadata’ options are set, it switches to verbose.
+
Temporally interleave frames from several inputs.
+
+
interleave works with video inputs, ainterleave with audio.
+
+
These filters read frames from several inputs and send the oldest
+queued frame to the output.
+
+
Input streams must have a well defined, monotonically increasing frame
+timestamp values.
+
+
In order to submit one frame to output, these filters need to enqueue
+at least one frame for each input, so they cannot work in case one
+input is not yet terminated and will not receive incoming frames.
+
+
For example consider the case when one input is a select filter
+which always drop input frames. The interleave filter will keep
+reading from that input, but it will never be able to send new frames
+to output until the input will send an end-of-stream signal.
+
+
Also, depending on inputs synchronization, the filters will drop
+frames in case one input receives more frames than the other ones, and
+the queue is already filled.
+
+
These filters accept the following options:
+
+
+
‘nb_inputs, n’
+
Set the number of different inputs, it is 2 by default.
+
Set read/write permissions for the output frames.
+
+
These filters are mainly aimed at developers to test direct path in the
+following filter in the filtergraph.
+
+
The filters accept the following options:
+
+
+
‘mode’
+
Select the permissions mode.
+
+
It accepts the following values:
+
+
‘none’
+
Do nothing. This is the default.
+
+
‘ro’
+
Set all the output frames read-only.
+
+
‘rw’
+
Set all the output frames directly writable.
+
+
‘toggle’
+
Make the frame read-only if writable, and writable if read-only.
+
+
‘random’
+
Set each output frame read-only or writable randomly.
+
+
+
+
+
‘seed’
+
Set the seed for the random mode, must be an integer included between
+0 and UINT32_MAX. If not specified, or if explicitly set to
+-1, the filter will try to use a good random seed on a best effort
+basis.
+
+
+
+
Note: in case of auto-inserted filter between the permission filter and the
+following one, the permission might not be received as expected in that
+following filter. Inserting a format or aformat filter before the
+perms/aperms filter can avoid this problem.
+
Set expression, which is evaluated for each input frame.
+
+
If the expression is evaluated to zero, the frame is discarded.
+
+
If the evaluation result is negative or NaN, the frame is sent to the
+first output; otherwise it is sent to the output with index
+ceil(val)-1, assuming that the input index starts from 0.
+
+
For example a value of 1.2 corresponds to the output with index
+ceil(1.2)-1 = 2-1 = 1, that is the second output.
+
+
+
‘outputs, n’
+
Set the number of outputs. The output to which to send the selected
+frame is based on the result of the evaluation. Default value is 1.
+
+
+
+
The expression can contain the following constants:
+
+
+
‘n’
+
the sequential number of the filtered frame, starting from 0
+
+
+
‘selected_n’
+
the sequential number of the selected frame, starting from 0
+
+
+
‘prev_selected_n’
+
the sequential number of the last selected frame, NAN if undefined
+
+
+
‘TB’
+
timebase of the input timestamps
+
+
+
‘pts’
+
the PTS (Presentation TimeStamp) of the filtered video frame,
+expressed in TB units, NAN if undefined
+
+
+
‘t’
+
the PTS (Presentation TimeStamp) of the filtered video frame,
+expressed in seconds, NAN if undefined
+
+
+
‘prev_pts’
+
the PTS of the previously filtered video frame, NAN if undefined
+
+
+
‘prev_selected_pts’
+
the PTS of the last previously filtered video frame, NAN if undefined
+
+
+
‘prev_selected_t’
+
the PTS of the last previously selected video frame, NAN if undefined
+
+
+
‘start_pts’
+
the PTS of the first video frame in the video, NAN if undefined
+
+
+
‘start_t’
+
the time of the first video frame in the video, NAN if undefined
+
+
+
‘pict_type (video only)’
+
the type of the filtered frame, can assume one of the following
+values:
+
+
‘I’
+
‘P’
+
‘B’
+
‘S’
+
‘SI’
+
‘SP’
+
‘BI’
+
+
+
+
‘interlace_type (video only)’
+
the frame interlace type, can assume one of the following values:
+
+
‘PROGRESSIVE’
+
the frame is progressive (not interlaced)
+
+
‘TOPFIRST’
+
the frame is top-field-first
+
+
‘BOTTOMFIRST’
+
the frame is bottom-field-first
+
+
+
+
+
‘consumed_sample_n (audio only)’
+
the number of selected samples before the current frame
+
+
+
‘samples_n (audio only)’
+
the number of samples in the current frame
+
+
+
‘sample_rate (audio only)’
+
the input sample rate
+
+
+
‘key’
+
1 if the filtered frame is a key-frame, 0 otherwise
+
+
+
‘pos’
+
the position in the file of the filtered frame, -1 if the information
+is not available (e.g. for synthetic video)
+
+
+
‘scene (video only)’
+
value between 0 and 1 to indicate a new scene; a low value reflects a low
+probability for the current frame to introduce a new scene, while a higher
+value means the current frame is more likely to be one (see the example below)
+
+
+
+
+
The default value of the select expression is "1".
+
These filters read commands to be sent to other filters in the
+filtergraph.
+
+
sendcmd must be inserted between two video filters,
+asendcmd must be inserted between two audio filters, but apart
+from that they act the same way.
+
+
The specification of commands can be provided in the filter arguments
+with the commands option, or in a file specified by the
+filename option.
+
+
These filters accept the following options:
+
+
‘commands, c’
+
Set the commands to be read and sent to the other filters.
+
+
‘filename, f’
+
Set the filename of the commands to be read and sent to the other
+filters.
+
A commands description consists of a sequence of interval
+specifications, comprising a list of commands to be executed when a
+particular event related to that interval occurs. The occurring event
+is typically the current frame time entering or leaving a given time
+interval.
+
+
An interval is specified by the following syntax:
+
START[-END] COMMANDS;
+
+
+
The time interval is specified by the START and END times.
+END is optional and defaults to the maximum time.
+
+
The current frame time is considered within the specified interval if
+it is included in the interval [START, END), that is when
+the time is greater or equal to START and is lesser than
+END.
+
+
COMMANDS consists of a sequence of one or more command
+specifications, separated by ",", relating to that interval. The
+syntax of a command specification is given by:
+
[FLAGS] TARGETCOMMANDARG
+
+
+
FLAGS is optional and specifies the type of events relating to
+the time interval which enable sending the specified command, and must
+be a non-null sequence of identifier flags separated by "+" or "|" and
+enclosed between "[" and "]".
+
+
The following flags are recognized:
+
+
‘enter’
+
The command is sent when the current frame timestamp enters the
+specified interval. In other words, the command is sent when the
+previous frame timestamp was not in the given interval, and the
+current is.
+
+
+
‘leave’
+
The command is sent when the current frame timestamp leaves the
+specified interval. In other words, the command is sent when the
+previous frame timestamp was in the given interval, and the
+current is not.
+
+
+
+
If FLAGS is not specified, a default value of [enter] is
+assumed.
+
+
TARGET specifies the target of the command, usually the name of
+the filter class or a specific filter instance name.
+
+
COMMAND specifies the name of the command for the target filter.
+
+
ARG is optional and specifies the optional list of argument for
+the given COMMAND.
+
+
Between one interval specification and another, whitespaces, or
+sequences of characters starting with # until the end of line,
+are ignored and can be used to annotate comments.
+
+
A simplified BNF description of the commands specification syntax
+follows:
+
+Specify a list of drawtext and hue commands in a file.
+
# show text in the interval 5-10
+5.0-10.0 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=hello world',
+ [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=';
+
+# desaturate the image in the interval 15-20
+15.0-20.0 [enter] hue s 0,
+ [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=nocolor',
+ [leave] hue s 1,
+ [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=color';
+
+# apply an exponential saturation fade-out effect, starting from time 25
+25 [enter] hue s exp(25-t)
+
+
+
A filtergraph allowing to read and process the above command list
+stored in a file ‘test.cmd’, can be specified with:
+
Set the timebase to use for the output frames timestamps.
+It is mainly useful for testing timebase configuration.
+
+
This filter accepts the following options:
+
+
+
‘expr, tb’
+
The expression which is evaluated into the output timebase.
+
+
+
+
+
The value for ‘tb’ is an arithmetic expression representing a
+rational. The expression can contain the constants "AVTB" (the default
+timebase), "intb" (the input timebase) and "sr" (the sample rate,
+audio only). Default value is "intb".
+
Convert input audio to a video output, representing the audio frequency
+spectrum.
+
+
The filter accepts the following options:
+
+
+
‘size, s’
+
Specify the video size for the output. For the syntax of this option, check
+the "Video size" section in the ffmpeg-utils manual. Default value is
+640x512.
+
+
+
‘slide’
+
Specify if the spectrum should slide along the window. Default value is
+0.
+
+
+
‘mode’
+
Specify display mode.
+
+
It accepts the following values:
+
+
‘combined’
+
all channels are displayed in the same row
+
+
‘separate’
+
all channels are displayed in separate rows
+
+
+
+
Default value is ‘combined’.
+
+
+
‘color’
+
Specify display color mode.
+
+
It accepts the following values:
+
+
‘channel’
+
each channel is displayed in a separate color
+
+
‘intensity’
+
each channel is is displayed using the same color scheme
+
+
+
+
Default value is ‘channel’.
+
+
+
‘scale’
+
Specify scale used for calculating intensity color values.
+
+
It accepts the following values:
+
+
‘lin’
+
linear
+
+
‘sqrt’
+
square root, default
+
+
‘cbrt’
+
cubic root
+
+
‘log’
+
logarithmic
+
+
+
+
Default value is ‘sqrt’.
+
+
+
‘saturation’
+
Set saturation modifier for displayed colors. Negative values provide
+alternative color scheme. 0 is no saturation at all.
+Saturation must be in [-10.0, 10.0] range.
+Default value is 1.
+
+
+
+
The usage is very similar to the showwaves filter; see the examples in that
+section.
+
Convert input audio to a video output, representing the samples waves.
+
+
The filter accepts the following options:
+
+
+
‘size, s’
+
Specify the video size for the output. For the syntax of this option, check
+the "Video size" section in the ffmpeg-utils manual. Default value
+is "600x240".
+
+
+
‘mode’
+
Set display mode.
+
+
Available values are:
+
+
‘point’
+
Draw a point for each sample.
+
+
+
‘line’
+
Draw a vertical line for each sample.
+
+
+
+
Default value is point.
+
+
+
‘n’
+
Set the number of samples which are printed on the same column. A
+larger value will decrease the frame rate. Must be a positive
+integer. This option can be set only if the value for rate
+is not explicitly specified.
+
+
+
‘rate, r’
+
Set the (approximate) output frame rate. This is done by setting the
+option n. Default value is "25".
+
The zmq and azmq filters work as a libzmq server, which
+receives messages sent through a network interface defined by the
+‘bind_address’ option.
+
+
The received message must be in the form:
+
TARGETCOMMAND [ARG]
+
+
+
TARGET specifies the target of the command, usually the name of
+the filter class or a specific filter instance name.
+
+
COMMAND specifies the name of the command for the target filter.
+
+
ARG is optional and specifies the optional argument list for the
+given COMMAND.
+
+
Upon reception, the message is processed and the corresponding command
+is injected into the filtergraph. Depending on the result, the filter
+will send a reply to the client, adopting the format:
+
Read audio and/or video stream(s) from a movie container.
+
+
This filter accepts the following options:
+
+
+
‘filename’
+
The name of the resource to read (not necessarily a file but also a device or a
+stream accessed through some protocol).
+
+
+
‘format_name, f’
+
Specifies the format assumed for the movie to read, and can be either
+the name of a container or an input device. If not specified the
+format is guessed from movie_name or by probing.
+
+
+
‘seek_point, sp’
+
Specifies the seek point in seconds, the frames will be output
+starting from this seek point, the parameter is evaluated with
+av_strtod so the numerical value may be suffixed by an IS
+postfix. Default value is "0".
+
+
+
‘streams, s’
+
Specifies the streams to read. Several streams can be specified,
+separated by "+". The source will then have as many outputs, in the
+same order. The syntax is explained in the “Stream specifiers”
+section in the ffmpeg manual. Two special names, "dv" and "da" specify
+respectively the default (best suited) video and audio stream. Default
+is "dv", or "da" if the filter is called as "amovie".
+
+
+
‘stream_index, si’
+
Specifies the index of the video stream to read. If the value is -1,
+the best suited video stream will be automatically selected. Default
+value is "-1". Deprecated. If the filter is called "amovie", it will select
+audio instead of video.
+
+
+
‘loop’
+
Specifies how many times to read the stream in sequence.
+If the value is less than 1, the stream will be read again and again.
+Default value is "1".
+
+
Note that when the movie is looped the source timestamps are not
+changed, so it will generate non monotonically increasing timestamps.
+
+
+
+
This filter allows to overlay a second video on top of main input of
+a filtergraph as shown in this graph:
+
+Read the first video stream and the audio stream with id 0x81 from
+dvd.vob; the video is connected to the pad named "video" and the audio is
+connected to the pad named "audio":
+
For details about the authorship, see the Git history of the project
+(git://source.ffmpeg.org/ffmpeg), e.g. by typing the command
+git log in the FFmpeg source directory, or browsing the
+online repository at http://source.ffmpeg.org.
+
+
Maintainers for the specific components are listed in the file
+‘MAINTAINERS’ in the source code tree.
+
@@ -235,42 +89,49 @@ ffprobe will show it.
and consists of one or more sections of a form defined by the selected
writer, which is specified by the ‘print_format’ option.
+
Sections may contain other nested sections, and are identified by a
+name (which may be shared by other sections), and an unique
+name. See the output of ‘sections’.
+
Metadata tags stored in the container or in the streams are recognized
-and printed in the corresponding "FORMAT" or "STREAM" section.
+and printed in the corresponding "FORMAT", "STREAM" or "PROGRAM_STREAM"
+section.
All the numerical options, if not specified otherwise, accept in input
-a string representing a number, which may contain one of the
-International System number postfixes, for example ’K’, ’M’, ’G’.
-If ’i’ is appended after the postfix, powers of 2 are used instead of
-powers of 10. The ’B’ postfix multiplies the value for 8, and can be
-appended after another postfix or used alone. This allows using for
-example ’KB’, ’MiB’, ’G’ and ’B’ as postfix.
+
All the numerical options, if not specified otherwise, accept a string
+representing a number as input, which may be followed by one of the SI
+unit prefixes, for example: ’K’, ’M’, or ’G’.
+
+
If ’i’ is appended to the SI unit prefix, the complete prefix will be
+interpreted as a unit prefix for binary multiplies, which are based on
+powers of 1024 instead of powers of 1000. Appending ’B’ to the SI unit
+prefix multiplies the value by 8. This allows using, for example:
+’KB’, ’MiB’, ’G’ and ’B’ as number suffixes.
Options which do not take arguments are boolean options, and set the
corresponding value to true. They can be set to false by prefixing
-with "no" the option name, for example using "-nofoo" in the
-command line will set to false the boolean option with name "foo".
+the option name with "no". For example using "-nofoo"
+will set the boolean option with name "foo" to false.
Some options are applied per-stream, e.g. bitrate or codec. Stream specifiers
-are used to precisely specify which stream(s) does a given option belong to.
+are used to precisely specify which stream(s) a given option belongs to.
A stream specifier is a string generally appended to the option name and
-separated from it by a colon. E.g. -codec:a:1 ac3 option contains
-a:1 stream specifer, which matches the second audio stream. Therefore it
+separated from it by a colon. E.g. -codec:a:1 ac3 contains the
+a:1 stream specifier, which matches the second audio stream. Therefore, it
would select the ac3 codec for the second audio stream.
-
A stream specifier can match several stream, the option is then applied to all
+
A stream specifier can match several streams, so that the option is applied to all
of them. E.g. the stream specifier in -b:a 128k matches all audio
streams.
-
An empty stream specifier matches all streams, for example -codec copy
+
An empty stream specifier matches all streams. For example, -codec copy
or -codec: copy would copy all the streams without reencoding.
Possible forms of stream specifiers are:
@@ -280,29 +141,73 @@ or -codec: copy would copy all the streams without reencoding.
thread count for the second stream to 4.
‘stream_type[:stream_index]’
-
stream_type is one of: ’v’ for video, ’a’ for audio, ’s’ for subtitle,
-’d’ for data and ’t’ for attachments. If stream_index is given, then
-matches stream number stream_index of this type. Otherwise matches all
+
stream_type is one of following: ’v’ for video, ’a’ for audio, ’s’ for subtitle,
+’d’ for data, and ’t’ for attachments. If stream_index is given, then it matches
+stream number stream_index of this type. Otherwise, it matches all
streams of this type.
‘p:program_id[:stream_index]’
-
If stream_index is given, then matches stream number stream_index in
-program with id program_id. Otherwise matches all streams in this program.
+
If stream_index is given, then it matches the stream with number stream_index
+in the program with the id program_id. Otherwise, it matches all streams in the
+program.
+
Show help. An optional parameter may be specified to print help about a specific
+item. If no argument is specified, only basic (non advanced) tool
+options are shown.
+
Possible values of arg are:
+
+
‘long’
+
Print advanced tool options in addition to the basic tool options.
+
+
+
‘full’
+
Print complete list of options, including shared and private options
+for encoders, decoders, demuxers, muxers, filters, etc.
+
+
+
‘decoder=decoder_name’
+
Print detailed information about the decoder named decoder_name. Use the
+‘-decoders’ option to get a list of all decoders.
+
+
+
‘encoder=encoder_name’
+
Print detailed information about the encoder named encoder_name. Use the
+‘-encoders’ option to get a list of all encoders.
+
+
+
‘demuxer=demuxer_name’
+
Print detailed information about the demuxer named demuxer_name. Use the
+‘-formats’ option to get a list of all demuxers and muxers.
+
+
+
‘muxer=muxer_name’
+
Print detailed information about the muxer named muxer_name. Use the
+‘-formats’ option to get a list of all muxers and demuxers.
+
+
+
‘filter=filter_name’
+
Print detailed information about the filter name filter_name. Use the
+‘-filters’ option to get a list of all filters.
+
+
+
‘-version’
Show version.
@@ -311,42 +216,21 @@ program with id program_id. Otherwise matches all streams in this pro
‘-formats’
Show available formats.
-
The fields preceding the format names have the following meanings:
-
-
‘D’
-
Decoding available
-
-
‘E’
-
Encoding available
-
-
-
‘-codecs’
-
Show available codecs.
+
Show all codecs known to libavcodec.
+
+
Note that the term ’codec’ is used throughout this documentation as a shortcut
+for what is more correctly called a media bitstream format.
+
+
+
‘-decoders’
+
Show available decoders.
+
+
+
‘-encoders’
+
Show all available encoders.
-
The fields preceding the codec names have the following meanings:
-
-
‘D’
-
Decoding available
-
-
‘E’
-
Encoding available
-
-
‘V/A/S’
-
Video/audio/subtitle codec
-
-
‘S’
-
Codec supports slices
-
-
‘D’
-
Codec supports direct rendering
-
-
‘T’
-
Codec can handle input truncated at random locations instead of only at frame boundaries
-
-
-
‘-bsfs’
Show available bitstream filters.
@@ -368,18 +252,52 @@ program with id program_id. Otherwise matches all streams in this pro
Show available sample formats.
-
‘-loglevel loglevel | -v loglevel’
+
‘-layouts’
+
Show channel names and standard channel layouts.
+
Set the logging level used by the library.
+Adding "repeat+" indicates that repeated log output should not be compressed
+to the first line and the "Last message repeated n times" line will be
+omitted. "repeat" can also be used alone.
+If "repeat" is used alone, and with no prior loglevel set, the default
+loglevel will be used. If multiple loglevel parameters are given, using
+’repeat’ will not change the loglevel.
loglevel is a number or a string containing one of the following values:
‘quiet’
+
Show nothing at all; be silent.
+
‘panic’
+
Only show fatal errors which could lead the process to crash, such as
+and assert failure. This is not currently used for anything.
+
‘fatal’
+
Only show fatal errors. These are errors after which the process absolutely
+cannot continue after.
+
‘error’
+
Show all errors, including ones which can be recovered from.
+
‘warning’
+
Show all warnings and errors. Any message related to possibly
+incorrect or unexpected events will be shown.
+
‘info’
+
Show informative messages during processing. This is in addition to
+warnings and errors. This is the default value.
+
‘verbose’
+
Same as info, except more verbose.
+
‘debug’
+
Show everything, including debugging information.
+
By default the program logs to stderr, if coloring is supported by the
@@ -398,10 +316,92 @@ directory.
This file can be useful for bug reports.
It also implies -loglevel verbose.
-
Note: setting the environment variable FFREPORT to any value has the
-same effect.
+
Setting the environment variable FFREPORT to any value has the
+same effect. If the value is a ’:’-separated key=value sequence, these
+options will affect the report; options values must be escaped if they
+contain special characters or the options delimiter ’:’ (see the
+“Quoting and escaping” section in the ffmpeg-utils manual). The
+following option is recognized:
+
+
‘file’
+
set the file name to use for the report; %p is expanded to the name
+of the program, %t is expanded to a timestamp, %% is expanded
+to a plain %
+
+
+
+
Errors in parsing the environment variable are not fatal, and will not
+appear in the report.
+
‘-cpuflags flags (global)’
+
Allows setting and clearing cpu flags. This option is intended
+for testing. Do not use it unless you know what you’re doing.
+
Set OpenCL environment options. This option is only available when
+FFmpeg has been compiled with --enable-opencl.
+
+
options must be a list of key=value option pairs
+separated by ’:’. See the “OpenCL Options” section in the
+ffmpeg-utils manual for the list of supported options.
+
@@ -428,14 +428,15 @@ muxer:
ffmpeg -i input.flac -id3v2_version 3 out.mp3
-
All codec AVOptions are obviously per-stream, so the chapter on stream
-specifiers applies to them
+
All codec AVOptions are per-stream, and thus a stream specifier
+should be attached to them.
-
Note ‘-nooption’ syntax cannot be used for boolean AVOptions,
-use ‘-option 0’/‘-option 1’.
+
Note: the ‘-nooption’ syntax cannot be used for boolean
+AVOptions, use ‘-option 0’/‘-option 1’.
-
Note2 old undocumented way of specifying per-stream AVOptions by prepending
-v/a/s to the options name is now obsolete and will be removed soon.
+
Note: the old undocumented way of specifying per-stream AVOptions by
+prepending v/a/s to the options name is now obsolete and will be
+removed soon.
writer_name specifies the name of the writer, and
@@ -482,6 +483,33 @@ options "-unit -prefix -byte_binary_prefix -sexagesimal".
Writers section below.
+
‘-sections’
+
Print sections structure and section information, and exit. The output
+is not meant to be parsed by a machine.
+
+
+
‘-select_streams stream_specifier’
+
Select only the streams specified by stream_specifier. This
+option affects only the options related to streams
+(e.g. show_streams, show_packets, etc.).
+
+
For example to show only audio streams, you can use the command:
+
ffprobe -show_streams -select_streams a INPUT
+
+
+
To show only video packets belonging to the video stream with index 1:
+
ffprobe -show_packets -select_streams v:1 INPUT
+
+
+
+
‘-show_data’
+
Show payload data, as a hexadecimal and ASCII dump. Coupled with
+‘-show_packets’, it will dump the packets’ data. Coupled with
+‘-show_streams’, it will dump the codec extradata.
+
+
The dump is printed as the "data" field. It may contain newlines.
+
+
‘-show_error’
Show information about the error found when trying to probe the input.
@@ -495,6 +523,61 @@ stream.
All the container format information is printed within a section with
name "FORMAT".
+
+
‘-show_format_entry name’
+
Like ‘-show_format’, but only prints the specified entry of the
+container format information, rather than all. This option may be given more
+than once, then all specified entries will be shown.
+
+
This option is deprecated, use show_entries instead.
+
+
+
‘-show_entries section_entries’
+
Set list of entries to show.
+
+
Entries are specified according to the following
+syntax. section_entries contains a list of section entries
+separated by :. Each section entry is composed by a section
+name (or unique name), optionally followed by a list of entries local
+to that section, separated by ,.
+
+
If section name is specified but is followed by no =, all
+entries are printed to output, together with all the contained
+sections. Otherwise only the entries specified in the local section
+entries list are printed. In particular, if = is specified but
+the list of local entries is empty, then no entries will be shown for
+that section.
+
+
Note that the order of specification of the local section entries is
+not honored in the output, and the usual display order will be
+retained.
+
For example, to show only the index and type of each stream, and the PTS
+time, duration time, and stream index of the packets, you can specify
+the argument:
+
To show all the entries in the section "format", but only the codec
+type in the section "stream", specify the argument:
+
format : stream=codec_type
+
+
+
To show all the tags in the stream and format sections:
+
format_tags : format_tags
+
+
+
To show only the title tag (if available) in the stream
+sections:
+
stream_tags=title
+
+
‘-show_packets’
Show information about each packet contained in the input multimedia
@@ -519,6 +602,90 @@ multimedia stream.
Each media stream information is printed within a dedicated section
with name "STREAM".
+
+
‘-show_programs’
+
Show information about programs and their streams contained in the input
+multimedia stream.
+
+
Each media stream information is printed within a dedicated section
+with name "PROGRAM_STREAM".
+
+
+
‘-show_chapters’
+
Show information about chapters stored in the format.
+
+
Each chapter is printed within a dedicated section with name "CHAPTER".
+
+
+
‘-count_frames’
+
Count the number of frames per stream and report it in the
+corresponding stream section.
+
+
+
‘-count_packets’
+
Count the number of packets per stream and report it in the
+corresponding stream section.
+
+
+
‘-read_intervals read_intervals’
+
+
Read only the specified intervals. read_intervals must be a
+sequence of interval specifications separated by ",".
+ffprobe will seek to the interval starting point, and will
+continue reading from that.
+
+
Each interval is specified by two optional parts, separated by "%".
+
+
The first part specifies the interval start position. It is
+interpreted as an abolute position, or as a relative offset from the
+current position if it is preceded by the "+" character. If this first
+part is not specified, no seeking will be performed when reading this
+interval.
+
+
The second part specifies the interval end position. It is interpreted
+as an absolute position, or as a relative offset from the current
+position if it is preceded by the "+" character. If the offset
+specification starts with "#", it is interpreted as the number of
+packets to read (not including the flushing packets) from the interval
+start. If no second part is specified, the program will read until the
+end of the input.
+
+
Note that seeking is not accurate, thus the actual interval start
+point may be different from the specified position. Also, when an
+interval duration is specified, the absolute end time will be computed
+by adding the duration to the interval start point found by seeking
+the file, rather than to the specified start value.
+
+Seek to time 10, read packets until 20 seconds after the found seek
+point, then seek to position 01:30 (1 minute and thirty
+seconds) and read packets until position 01:45.
+
10%+20,01:30%01:45
+
+
+
+Read only 42 packets after seeking to position 01:23:
+
01:23%+#42
+
+
+
+Read only the first 20 seconds from the start:
+
%+20
+
+
+
+Read from the start until position 02:30:
+
%02:30
+
+
+
‘-show_private_data, -private’
Show private data, that is data depending on the format of the
@@ -547,6 +714,11 @@ equivalent of setting both ‘-show_program_version’ and
‘-show_library_versions’ options.
+
‘-bitexact’
+
Force bitexact output, useful to produce output which is not dependent
+on the specific build.
+
+
‘-i input_file’
Read input_file.
@@ -559,8 +731,9 @@ equivalent of setting both ‘-show_program_version’ and
A writer defines the output format adopted by ffprobe, and will be
used for printing all the parts of the output.
-
A writer may accept one or more arguments, which specify the options to
-adopt.
+
A writer may accept one or more arguments, which specify the options
+to adopt. The options are specified as a list of key=value
+pairs, separated by ":".
A description of the currently available writers follows.
@@ -576,12 +749,29 @@ keyN=valN
[/SECTION]
-
Metadata tags are printed as a line in the corresponding FORMAT or
-STREAM section, and are prefixed by the string "TAG:".
+
Metadata tags are printed as a line in the corresponding FORMAT, STREAM or
+PROGRAM_STREAM section, and are prefixed by the string "TAG:".
The csv writer is equivalent to compact, but supports
+different defaults.
Each section is printed on a single line.
If no option is specifid, the output has the form:
@@ -592,31 +782,30 @@ If no option is specifid, the output has the form:
section. A metadata tag key, if printed, is prefixed by the string
"tag:".
-
This writer accepts options as a list of key=value pairs,
-separated by ":".
-
The description of the accepted options follows.
‘item_sep, s’
Specify the character to use for separating fields in the output line.
-It must be a single printable character, it is "|" by default.
+It must be a single printable character, it is "|" by default ("," for
+the csv writer).
‘nokey, nk’
If set to 1 specify not to print the key of each field. Its default
-value is 0.
+value is 0 (1 for the csv writer).
‘escape, e’
-
Set the escape mode to use, default to "c".
+
Set the escape mode to use, default to "c" ("csv" for the csv
+writer).
It can assume one of the following values:
‘c’
-
Perform C-like escaping. Strings containing a newline (’\n’) or
-carriage return (’\r’), the escaping character (’\’) or the item
-separator character SEP are escaped using C-like fashioned
+
Perform C-like escaping. Strings containing a newline (’\n’), carriage
+return (’\r’), a tab (’\t’), a form feed (’\f’), the escaping
+character (’\’) or the item separator character SEP are escaped using C-like fashioned
escaping, so that a newline is converted to the sequence "\n", a
carriage return to "\r", ’\’ to "\\" and the separator SEP is
converted to "\SEP".
@@ -633,25 +822,91 @@ containing a newline (’\n’), a carriage return (’\r’), a
+
+
‘print_section, p’
+
Print the section name at the begin of each line if the value is
+1, disable it with value set to 0. Default value is
+1.
+
This writer is equivalent to
-compact=item_sep=,:nokey=1:escape=csv.
+
A free-form output where each line contains an explicit key=value, such as
+"streams.stream.3.tags.foo=bar". The output is shell escaped, so it can be
+directly embedded in sh scripts as long as the separator character is an
+alphanumeric character or an underscore (see sep_char option).
+
The description of the accepted options follows.
+
+
+
‘sep_char, s’
+
Separator character used to separate the chapter, the section name, IDs and
+potential tags in the printed field key.
+
+
Default value is ’.’.
+
+
+
‘hierarchical, h’
+
Specify if the section name specification should be hierarchical. If
+set to 1, and if there is more than one section in the current
+chapter, the section name will be prefixed by the name of the
+chapter. A value of 0 will disable this behavior.
+
+newline, ’\t’, ’\f’, ’\b’ and the following characters are escaped
+
+’\’ is the escape character
+
+’#’ is the comment indicator
+
+’=’ is the key/value separator
+
+’:’ is not used but usually parsed as key/value separator
+
+
+
This writer accepts options as a list of key=value pairs,
+separated by ":".
+
+
The description of the accepted options follows.
+
+
+
‘hierarchical, h’
+
Specify if the section name specification should be hierarchical. If
+set to 1, and if there is more than one section in the current
+chapter, the section name will be prefixed by the name of the
+chapter. A value of 0 will disable this behavior.
+
The XML output is described in the XML schema description file
‘ffprobe.xsd’ installed in the FFmpeg datadir.
+
An updated version of the schema can be retrieved at the url
+http://www.ffmpeg.org/schema/ffprobe.xsd, which redirects to the
+latest schema committed into the FFmpeg development source code tree.
+
Note that the output issued will be compliant to the
‘ffprobe.xsd’ schema only when no special global output options
(‘unit’, ‘prefix’, ‘byte_binary_prefix’,
‘sexagesimal’ etc.) are specified.
-
This writer accepts options as a list of key=value pairs,
-separated by ":".
-
The description of the accepted options follows.
@@ -704,1333 +960,50 @@ This option automatically sets ‘fully_qualified’ to 1.
ffprobe supports Timecode extraction:
-
MPEG1/2 timecode is extracted from the GOP, and is available in the video
+
+MPEG1/2 timecode is extracted from the GOP, and is available in the video
stream details (‘-show_streams’, see timecode).
-
MOV timecode is extracted from tmcd track, so is available in the tmcd
+
+MOV timecode is extracted from tmcd track, so is available in the tmcd
stream metadata (‘-show_streams’, see TAG:timecode).
-
DV and GXF timecodes are available in format metadata
+
+DV, GXF and AVI timecodes are available in format metadata
(‘-show_format’, see TAG:timecode).
When you configure your FFmpeg build, all the supported native decoders
-are enabled by default. Decoders requiring an external library must be enabled
-manually via the corresponding --enable-lib option. You can list all
-available decoders using the configure option --list-decoders.
-
-
You can disable all the decoders with the configure option
---disable-decoders and selectively enable / disable single decoders
-with the options --enable-decoder=DECODER /
---disable-decoder=DECODER.
-
-
The option -codecs of the ff* tools will display the list of
-enabled decoders.
-
This decoder generates wave patterns according to predefined sequences. Its
-use is purely internal and the format of the data it accepts is not publicly
-documented.
-
Demuxers are configured elements in FFmpeg which allow to read the
-multimedia streams from a particular type of file.
-
-
When you configure your FFmpeg build, all the supported demuxers
-are enabled by default. You can list all available ones using the
-configure option "–list-demuxers".
-
-
You can disable all the demuxers using the configure option
-"–disable-demuxers", and selectively enable a single demuxer with
-the option "–enable-demuxer=DEMUXER", or disable it
-with the option "–disable-demuxer=DEMUXER".
-
-
The option "-formats" of the ff* tools will display the list of
-enabled demuxers.
-
-
The description of some of the currently available demuxers follows.
-
This demuxer reads from a list of image files specified by a pattern.
-
-
The pattern may contain the string "%d" or "%0Nd", which
-specifies the position of the characters representing a sequential
-number in each filename matched by the pattern. If the form
-"%d0Nd" is used, the string representing the number in each
-filename is 0-padded and N is the total number of 0-padded
-digits representing the number. The literal character ’%’ can be
-specified in the pattern with the string "%%".
-
-
If the pattern contains "%d" or "%0Nd", the first filename of
-the file list specified by the pattern must contain a number
-inclusively contained between 0 and 4, all the following numbers must
-be sequential. This limitation may be hopefully fixed.
-
-
The pattern may contain a suffix which is used to automatically
-determine the format of the images contained in the files.
-
-
For example the pattern "img-%03d.bmp" will match a sequence of
-filenames of the form ‘img-001.bmp’, ‘img-002.bmp’, ...,
-‘img-010.bmp’, etc.; the pattern "i%%m%%g-%d.jpg" will match a
-sequence of filenames of the form ‘i%m%g-1.jpg’,
-‘i%m%g-2.jpg’, ..., ‘i%m%g-10.jpg’, etc.
-
-
The size, the pixel format, and the format of each image must be the
-same for all the files in the sequence.
-
-
The following example shows how to use ffmpeg for creating a
-video from the images in the file sequence ‘img-001.jpeg’,
-‘img-002.jpeg’, ..., assuming an input frame rate of 10 frames per
-second:
-
ffmpeg -i 'img-%03d.jpeg' -r 10 out.mkv
-
-
-
Note that the pattern must not necessarily contain "%d" or
-"%0Nd", for example to convert a single image file
-‘img.jpeg’ you can employ the command:
-
This demuxer presents all AVStreams from all variant streams.
-The id field is set to the bitrate variant index number. By setting
-the discard flags on AVStreams (by pressing ’a’ or ’v’ in ffplay),
-the caller can decide which variant streams to actually receive.
-The total bitrate of the variant that the stream belongs to is
-available in a metadata key named "variant_bitrate".
-
This demuxer reads the script language used by SBaGen
-http://uazu.net/sbagen/ to generate binaural beats sessions. A SBG
-script looks like that:
-
-SE
-a: 300-2.5/3 440+4.5/0
-b: 300-2.5/0 440+4.5/3
-off: -
-NOW == a
-+0:07:00 == b
-+0:14:00 == a
-+0:21:00 == b
-+0:30:00 off
-
-
-
A SBG script can mix absolute and relative timestamps. If the script uses
-either only absolute timestamps (including the script start time) or only
-relative ones, then its layout is fixed, and the conversion is
-straightforward. On the other hand, if the script mixes both kind of
-timestamps, then the NOW reference for relative timestamps will be
-taken from the current time of day at the time the script is read, and the
-script layout will be frozen according to that reference. That means that if
-the script is directly played, the actual times will match the absolute
-timestamps up to the sound controller’s clock accuracy, but if the user
-somehow pauses the playback or seeks, all times will be shifted accordingly.
-
Protocols are configured elements in FFmpeg which allow to access
-resources which require the use of a particular protocol.
-
-
When you configure your FFmpeg build, all the supported protocols are
-enabled by default. You can list all available ones using the
-configure option "–list-protocols".
-
-
You can disable all the protocols using the configure option
-"–disable-protocols", and selectively enable a protocol using the
-option "–enable-protocol=PROTOCOL", or you can disable a
-particular protocol using the option
-"–disable-protocol=PROTOCOL".
-
-
The option "-protocols" of the ff* tools will display the list of
-supported protocols.
-
-
A description of the currently available protocols follows.
-
Read Apple HTTP Live Streaming compliant segmented stream as
-a uniform one. The M3U8 playlists describing the segments can be
-remote HTTP resources or local files, accessed using the standard
-file protocol.
-HTTP is default, specific protocol can be declared by specifying
-"+proto" after the applehttp URI scheme name, where proto
-is either "file" or "http".
-
For details about the authorship, see the Git history of the project
+(git://source.ffmpeg.org/ffmpeg), e.g. by typing the command
+git log in the FFmpeg source directory, or browsing the
+online repository at http://source.ffmpeg.org.
Computes the MD5 hash of the data to be written, and on close writes
-this to the designated output or stdout if none is specified. It can
-be used to test muxers without writing an actual file.
-
-
Some examples follow.
-
# Write the MD5 hash of the encoded AVI file to the file output.avi.md5.
-ffmpeg -i input.flv -f avi -y md5:output.avi.md5
-
-# Write the MD5 hash of the encoded AVI file to stdout.
-ffmpeg -i input.flv -f avi -y md5:
-
-
-
Note that some formats (typically MOV) require the output protocol to
-be seekable, so they will fail with the MD5 output protocol.
-
number is the number corresponding to the file descriptor of the
-pipe (e.g. 0 for stdin, 1 for stdout, 2 for stderr). If number
-is not specified, by default the stdout file descriptor will be used
-for writing, stdin for reading.
-
-
For example to read from stdin with ffmpeg:
-
cat test.wav | ffmpeg -i pipe:0
-# ...this is the same as...
-cat test.wav | ffmpeg -i pipe:
-
-
-
For writing to stdout with ffmpeg:
-
ffmpeg -i test.wav -f avi pipe:1 | cat > test.avi
-# ...this is the same as...
-ffmpeg -i test.wav -f avi pipe: | cat > test.avi
-
-
-
Note that some formats (typically MOV), require the output protocol to
-be seekable, so they will fail with the pipe output protocol.
-
The Real-Time Messaging Protocol (RTMP) is used for streaming multimedia
-content across a TCP/IP network.
-
-
The required syntax is:
-
rtmp://server[:port][/app][/playpath]
-
-
-
The accepted parameters are:
-
-
‘server’
-
The address of the RTMP server.
-
-
-
‘port’
-
The number of the TCP port to use (by default is 1935).
-
-
-
‘app’
-
It is the name of the application to access. It usually corresponds to
-the path where the application is installed on the RTMP server
-(e.g. ‘/ondemand/’, ‘/flash/live/’, etc.).
-
-
-
‘playpath’
-
It is the path or name of the resource to play with reference to the
-application specified in app, may be prefixed by "mp4:".
-
-
-
-
-
For example to read with ffplay a multimedia resource named
-"sample" from the application "vod" from an RTMP server "myserver":
-
Real-Time Messaging Protocol and its variants supported through
-librtmp.
-
-
Requires the presence of the librtmp headers and library during
-configuration. You need to explicitly configure the build with
-"–enable-librtmp". If enabled this will replace the native RTMP
-protocol.
-
-
This protocol provides most client functions and a few server
-functions needed to support RTMP, RTMP tunneled in HTTP (RTMPT),
-encrypted RTMP (RTMPE), RTMP over SSL/TLS (RTMPS) and tunneled
-variants of these encrypted types (RTMPTE, RTMPTS).
-
where rtmp_proto is one of the strings "rtmp", "rtmpt", "rtmpe",
-"rtmps", "rtmpte", "rtmpts" corresponding to each RTMP variant, and
-server, port, app and playpath have the same
-meaning as specified for the RTMP native protocol.
-options contains a list of space-separated options of the form
-key=val.
-
-
See the librtmp manual page (man 3 librtmp) for more information.
-
-
For example, to stream a file in real-time to an RTMP server using
-ffmpeg:
-
RTSP is not technically a protocol handler in libavformat, it is a demuxer
-and muxer. The demuxer supports both normal RTSP (with data transferred
-over RTP; this is used by e.g. Apple and Microsoft) and Real-RTSP (with
-data transferred over RDT).
-
-
The muxer can be used to send a stream using RTSP ANNOUNCE to a server
-supporting it (currently Darwin Streaming Server and Mischa Spiegelmock’s
-RTSP server).
-
-
The required syntax for a RTSP url is:
-
rtsp://hostname[:port]/path
-
-
-
The following options (set on the ffmpeg/ffplay command
-line, or set in code via AVOptions or in avformat_open_input),
-are supported:
-
-
Flags for rtsp_transport:
-
-
-
‘udp’
-
Use UDP as lower transport protocol.
-
-
-
‘tcp’
-
Use TCP (interleaving within the RTSP control channel) as lower
-transport protocol.
-
-
-
‘udp_multicast’
-
Use UDP multicast as lower transport protocol.
-
-
-
‘http’
-
Use HTTP tunneling as lower transport protocol, which is useful for
-passing proxies.
-
-
-
-
Multiple lower transport protocols may be specified, in that case they are
-tried one at a time (if the setup of one fails, the next one is tried).
-For the muxer, only the tcp and udp options are supported.
-
-
Flags for rtsp_flags:
-
-
-
‘filter_src’
-
Accept packets only from negotiated peer address and port.
-
-
-
-
When receiving data over UDP, the demuxer tries to reorder received packets
-(since they may arrive out of order, or packets may get lost totally). In
-order for this to be enabled, a maximum delay must be specified in the
-max_delay field of AVFormatContext.
-
-
When watching multi-bitrate Real-RTSP streams with ffplay, the
-streams to display can be chosen with -vstn and
--astn for video and audio respectively, and can be switched
-on the fly by pressing v and a.
-
-
Example command lines:
-
-
To watch a stream over UDP, with a max reordering delay of 0.5 seconds:
-
Session Announcement Protocol (RFC 2974). This is not technically a
-protocol handler in libavformat, it is a muxer and demuxer.
-It is used for signalling of RTP streams, by announcing the SDP for the
-streams regularly on a separate port.
-
The RTP packets are sent to destination on port port,
-or to port 5004 if no port is specified.
-options is a &-separated list. The following options
-are supported:
-
-
-
‘announce_addr=address’
-
Specify the destination IP address for sending the announcements to.
-If omitted, the announcements are sent to the commonly used SAP
-announcement multicast address 224.2.127.254 (sap.mcast.net), or
-ff0e::2:7ffe if destination is an IPv6 address.
-
-
-
‘announce_port=port’
-
Specify the port to send the announcements on, defaults to
-9875 if not specified.
-
-
-
‘ttl=ttl’
-
Specify the time to live value for the announcements and RTP packets,
-defaults to 255.
-
-
-
‘same_port=0|1’
-
If set to 1, send all RTP streams on the same port pair. If zero (the
-default), all streams are sent on unique ports, with each stream on a
-port 2 numbers higher than the previous.
-VLC/Live555 requires this to be set to 1, to be able to receive the stream.
-The RTP stack in libavformat for receiving requires all streams to be sent
-on unique ports.
-
-
-
-
Example command lines follow.
-
-
To broadcast a stream on the local subnet, for watching in VLC:
-
-
ffmpeg -re -i input -f sap sap://224.0.0.255?same_port=1
-
-
-
Similarly, for watching in ffplay:
-
-
ffmpeg -re -i input -f sap sap://224.0.0.255
-
-
-
And for watching in ffplay, over IPv6:
-
-
ffmpeg -re -i input -f sap sap://[ff0e::1:2:3:4]
-
The syntax for a SAP url given to the demuxer is:
-
sap://[address][:port]
-
-
-
address is the multicast address to listen for announcements on,
-if omitted, the default 224.2.127.254 (sap.mcast.net) is used. port
-is the port that is listened on, 9875 if omitted.
-
-
The demuxers listens for announcements on the given address and port.
-Once an announcement is received, it tries to receive that particular stream.
-
-
Example command lines follow.
-
-
To play back the first stream announced on the normal SAP multicast address:
-
-
ffplay sap://
-
-
-
To play back the first stream announced on one the default IPv6 SAP multicast address:
-
options contains a list of &-seperated options of the form key=val.
-Follow the list of supported options.
-
-
-
‘buffer_size=size’
-
set the UDP buffer size in bytes
-
-
-
‘localport=port’
-
override the local UDP port to bind with
-
-
-
‘localaddr=addr’
-
Choose the local IP address. This is useful e.g. if sending multicast
-and the host has multiple interfaces, where the user can choose
-which interface to send on by specifying the IP address of that interface.
-
-
-
‘pkt_size=size’
-
set the size in bytes of UDP packets
-
-
-
‘reuse=1|0’
-
explicitly allow or disallow reusing UDP sockets
-
-
-
‘ttl=ttl’
-
set the time to live value (for multicast only)
-
-
-
‘connect=1|0’
-
Initialize the UDP socket with connect(). In this case, the
-destination address can’t be changed with ff_udp_set_remote_url later.
-If the destination address isn’t known at the start, this option can
-be specified in ff_udp_set_remote_url, too.
-This allows finding out the source address for the packets with getsockname,
-and makes writes return with AVERROR(ECONNREFUSED) if "destination
-unreachable" is received.
-For receiving, this gives the benefit of only receiving packets from
-the specified peer address/port.
-
-
-
-
Some usage examples of the udp protocol with ffmpeg follow.
-
-
To stream over UDP to a remote endpoint:
-
ffmpeg -i input -f format udp://hostname:port
-
-
-
To stream in mpegts format over UDP using 188 sized UDP packets, using a large input buffer:
-
Input devices are configured elements in FFmpeg which allow to access
-the data coming from a multimedia device attached to your system.
-
-
When you configure your FFmpeg build, all the supported input devices
-are enabled by default. You can list all available ones using the
-configure option "–list-indevs".
-
-
You can disable all the input devices using the configure option
-"–disable-indevs", and selectively enable an input device using the
-option "–enable-indev=INDEV", or you can disable a particular
-input device using the option "–disable-indev=INDEV".
-
-
The option "-formats" of the ff* tools will display the list of
-supported input devices (amongst the demuxers).
-
-
A description of the currently available input devices follows.
-
The Linux framebuffer is a graphic hardware-independent abstraction
-layer to show graphics on a computer monitor, typically on the
-console. It is accessed through a file device node, usually
-‘/dev/fb0’.
-
-
For more detailed information read the file
-Documentation/fb/framebuffer.txt included in the Linux source tree.
-
-
To record from the framebuffer device ‘/dev/fb0’ with
-ffmpeg:
-
ffmpeg -f fbdev -r 10 -i /dev/fb0 out.avi
-
-
-
You can take a single screenshot image with the command:
-
To enable this input device during configuration you need libjack
-installed on your system.
-
-
A JACK input device creates one or more JACK writable clients, one for
-each audio channel, with name client_name:input_N, where
-client_name is the name provided by the application, and N
-is a number which identifies the channel.
-Each writable client will send the acquired data to the FFmpeg input
-device.
-
-
Once you have created one or more JACK readable clients, you need to
-connect them to one or more JACK writable clients.
-
-
To connect or disconnect JACK clients you can use the jack_connect
-and jack_disconnect programs, or do it through a graphical interface,
-for example with qjackctl.
-
-
To list the JACK clients and their properties you can invoke the command
-jack_lsp.
-
-
Follows an example which shows how to capture a JACK readable client
-with ffmpeg.
-
# Create a JACK writable client with name "ffmpeg".
-$ ffmpeg -f jack -i ffmpeg -y out.wav
-
-# Start the sample jack_metro readable client.
-$ jack_metro -b 120 -d 0.2 -f 4000
-
-# List the current JACK clients.
-$ jack_lsp -c
-system:capture_1
-system:capture_2
-system:playback_1
-system:playback_2
-ffmpeg:input_1
-metro:120_bpm
-
-# Connect metro to the ffmpeg writable client.
-$ jack_connect metro:120_bpm ffmpeg:input_1
-
This input device reads data from the open output pads of a libavfilter
-filtergraph.
-
-
For each filtergraph open output, the input device will create a
-corresponding stream which is mapped to the generated output. Currently
-only video data is supported. The filtergraph is specified through the
-option ‘graph’.
-
Specify the filtergraph to use as input. Each video open output must be
-labelled by a unique string of the form "outN", where N is a
-number starting from 0 corresponding to the mapped input stream
-generated by the device.
-The first unlabelled output is automatically assigned to the "out0"
-label, but all the others need to be specified explicitly.
-
-
If not specified defaults to the filename specified for the input
-device.
-
The OpenAL input device provides audio capture on all systems with a
-working OpenAL 1.1 implementation.
-
-
To enable this input device during configuration, you need OpenAL
-headers and libraries installed on your system, and need to configure
-FFmpeg with --enable-openal.
-
-
OpenAL headers and libraries should be provided as part of your OpenAL
-implementation, or as an additional download (an SDK). Depending on your
-installation you may need to specify additional flags via the
---extra-cflags and --extra-ldflags for allowing the build
-system to locate the OpenAL headers and libraries.
-
-
An incomplete list of OpenAL implementations follows:
-
-
-
Creative
-
The official Windows implementation, providing hardware acceleration
-with supported devices and software fallback.
-See http://openal.org/.
-
-
OpenAL Soft
-
Portable, open source (LGPL) software implementation. Includes
-backends for the most common sound APIs on the Windows, Linux,
-Solaris, and BSD operating systems.
-See http://kcat.strangesoft.net/openal.html.
-
This device allows to capture from an audio input device handled
-through OpenAL.
-
-
You need to specify the name of the device to capture in the provided
-filename. If the empty string is provided, the device will
-automatically select the default device. You can get the list of the
-supported devices by using the option list_devices.
-
Video4Linux and Video4Linux2 input video devices.
-
-
The name of the device to grab is a file device node, usually Linux
-systems tend to automatically create such nodes when the device
-(e.g. an USB webcam) is plugged into the system, and has a name of the
-kind ‘/dev/videoN’, where N is a number associated to
-the device.
-
-
Video4Linux and Video4Linux2 devices only support a limited set of
-widthxheight sizes and framerates. You can check which are
-supported for example with the command dov4l for Video4Linux
-devices and using -list_formats all for Video4Linux2 devices.
-
-
If the size for the device is set to 0x0, the input device will
-try to auto-detect the size to use.
-Only for the video4linux2 device, if the frame rate is set to 0/0 the
-input device will use the frame rate value already set in the driver.
-
-
Video4Linux support is deprecated since Linux 2.6.30, and will be
-dropped in later versions.
-
-
Note that if FFmpeg is build with v4l-utils support ("–enable-libv4l2"
-option), it will always be used.
-
-
Follow some usage examples of the video4linux devices with the ff*
-tools.
-
# Grab and show the input of a video4linux device, frame rate is set
-# to the default of 25/1.
-ffplay -s 320x240 -f video4linux /dev/video0
-
-# Grab and show the input of a video4linux2 device, auto-adjust size.
-ffplay -f video4linux2 /dev/video0
-
-# Grab and record the input of a video4linux2 device, auto-adjust size,
-# frame rate value defaults to 0/0 so it is read from the video4linux2
-# driver.
-ffmpeg -f video4linux2 -i /dev/video0 out.mpeg
-
-
-
"v4l" and "v4l2" can be used as aliases for the respective "video4linux" and
-"video4linux2".
-
The filename passed as input is the capture driver number, ranging from
-0 to 9. You may use "list" as filename to print a list of drivers. Any
-other filename will be interpreted as device number 0.
-
hostname:display_number.screen_number specifies the
-X11 display name of the screen to grab from. hostname can be
-omitted, and defaults to "localhost". The environment variable
-DISPLAY contains the default display name.
-
-
x_offset and y_offset specify the offsets of the grabbed
-area with respect to the top-left border of the X11 screen. They
-default to 0.
-
-
Check the X11 documentation (e.g. man X) for more detailed information.
-
-
Use the dpyinfo program for getting basic information about the
-properties of your X11 display (e.g. grep for "name" or "dimensions").
-
When it is specified with "centered", the grabbing region follows the mouse
-pointer and keeps the pointer at the center of region; otherwise, the region
-follows only when the mouse pointer reaches within PIXELS (greater than
-zero) to the edge of region.
-
-
For example:
-
ffmpeg -f x11grab -follow_mouse centered -r 25 -s cif -i :0.0 out.mpg
-
-# Follows only when the mouse pointer reaches within 100 pixels to edge
-ffmpeg -f x11grab -follow_mouse 100 -r 25 -s cif -i :0.0 out.mpg
-
If show_region AVOption is specified with 1, then the grabbing
-region will be indicated on screen. With this option, it’s easy to know what is
-being grabbed if only a portion of the screen is grabbed.
-
FFmpeg can be hooked up with a number of external libraries to add support
for more formats. None of them are used by default, their use has to be
-explicitly requested by passing the appropriate flags to ‘./configure’.
+explicitly requested by passing the appropriate flags to
+./configure.
Spun off Google Android sources, OpenCore and VisualOn libraries provide
-encoders for a number of audio codecs.
+
Spun off Google Android sources, OpenCore, VisualOn and Fraunhofer
+libraries provide encoders for a number of audio codecs.
-
+
OpenCORE and VisualOn libraries are under the Apache License 2.0
(see http://www.apache.org/licenses/LICENSE-2.0 for details), which is
-incompatible with the LGPL version 2.1 and GPL version 2. You have to
+incompatible to the LGPL version 2.1 and GPL version 2. You have to
upgrade FFmpeg’s license to LGPL version 3 (or if you have enabled
-GPL components, GPL version 3) to use it.
+GPL components, GPL version 3) by passing --enable-version3 to configure in
+order to use it.
+
+
The Fraunhofer AAC library is licensed under a license incompatible to the GPL
+and is not known to be compatible to the LGPL. Therefore, you have to pass
+--enable-nonfree to configure to use it.
@@ -179,6 +131,15 @@ Then pass --enable-libvo-aacenc to configure to enable it.
instructions for installing the library.
Then pass --enable-libvo-amrwbenc to configure to enable it.
+
+
@@ -188,17 +149,35 @@ Then pass --enable-libvo-amrwbenc to configure to enable it.
instructions for installing the library.
Then pass --enable-libmp3lame to configure to enable it.
-
-
iLBC is a narrowband speech codec that has been made freely available
+by Google as part of the WebRTC project. libilbc is a packaging friendly
+copy of the iLBC codec. FFmpeg can make use of the libilbc library for
+iLBC encoding and decoding.
+
+
Go to https://github.com/dekkers/libilbc and follow the instructions for
+installing the library. Then pass --enable-libilbc to configure to
+enable it.
+
libzvbi is a VBI decoding library which can be used by FFmpeg to decode DVB
+teletext pages and DVB teletext subtitles.
+
+
Go to http://sourceforge.net/projects/zapping/ and follow the instructions for
+installing the library. Then pass --enable-libzvbi to configure to
+enable it.
+
+
+
libzvbi is licensed under the GNU General Public License Version 2 or later
+(see http://www.gnu.org/licenses/old-licenses/gpl-2.0.html for details),
+you must upgrade FFmpeg’s license to GPL in order to use it.
+
@@ -174,6 +121,13 @@ Most distribution and operating system provide a package for it.
This will put the FFmpeg sources into the directory <target> and let
you push back your changes to the remote repository.
+
Make sure that you do not have Windows line endings in your checkouts,
+otherwise you may experience spurious compilation failures. One way to
+achieve this is to run
+
@@ -185,7 +139,7 @@ you push back your changes to the remote repository.
can be remote. By default the master branch tracks the branch master in
the remote origin.
-
In order to have git send-email automatically send patches
+to the ffmpeg-devel mailing list, add the following stanza
+to ‘/path/to/ffmpeg/repository/.git/config’:
+
will replay local commits over the main repository allowing to edit, merge
or remove some of them in the process.
-
+
git reset, git commit --amend and git rebase
rewrite history, so you should use them ONLY on your local or topic branches.
The main repository will reject those changes.
@@ -385,7 +366,7 @@ The main repository will reject those changes.
faulty commit disappear from the history.
Since version 1.7.1 git supports :/foo syntax for specifying commits
based on a regular expression. see man gitrevisions
@@ -431,19 +412,48 @@ This commit can be checked out with
where $SHA1 is the commit hash from the git log output.
Once you have a set of commits that you feel are ready for pushing,
+work through the following checklist to doublecheck everything is in
+proper order. This list tries to be exhaustive. In case you are just
+pushing a typo in a comment, some of the steps may be unnecessary.
+Apply your common sense, but if in doubt, err on the side of caution.
+
+
First, make sure that the commits and branches you are going to push
+match what you want pushed and that nothing is missing, extraneous or
+wrong. You can see what will be pushed by running the git push command
+with –dry-run first. And then inspecting the commits listed with
+git log -p 1234567..987654. The git status command
+may help in finding local changes that have been forgotten to be added.
+
+
Next let the code pass through a full run of our testsuite.
+
+
+
make distclean
+
/path/to/ffmpeg/configure
+
make check
+
if fate fails due to missing samples run make fate-rsync and retry
+
+
+
Make sure all your changes have been checked before pushing them, the
+testsuite only checks against regressions and that only to some extend. It does
+obviously not check newly added features/code to be working unless you have
+added a test for that (which is recommended).
+
+
Also note that every single commit should pass the test suite, not just
+the result of a series of patches.
+
+
Once everything passed, push the changes to your public ffmpeg clone and post a
+merge request to ffmpeg-devel. You can also push them directly but this is not
+recommended.
+
The libavcodec library provides a generic encoding/decoding framework
+and contains multiple decoders and encoders for audio, video and
+subtitle streams, and several bitstream filters.
+
+
The shared architecture provides various services ranging from bit
+stream I/O to DSP optimizations, and makes it suitable for
+implementing robust and fast codecs as well as for experimentation.
+
For details about the authorship, see the Git history of the project
+(git://source.ffmpeg.org/ffmpeg), e.g. by typing the command
+git log in the FFmpeg source directory, or browsing the
+online repository at http://source.ffmpeg.org.
+
+
Maintainers for the specific components are listed in the file
+‘MAINTAINERS’ in the source code tree.
+
The libavdevice library provides a generic framework for grabbing from
+and rendering to many common multimedia input/output devices, and
+supports several input and output devices, including Video4Linux2,
+VfW, DShow, and ALSA.
+
For details about the authorship, see the Git history of the project
+(git://source.ffmpeg.org/ffmpeg), e.g. by typing the command
+git log in the FFmpeg source directory, or browsing the
+online repository at http://source.ffmpeg.org.
+
+
Maintainers for the specific components are listed in the file
+‘MAINTAINERS’ in the source code tree.
+
In libavfilter, it is possible for filters to have multiple inputs and
-multiple outputs.
-To illustrate the sorts of things that are possible, we can
-use a complex filter graph. For example, the following one:
-
splits the stream in two streams, sends one stream through the crop filter
-and the vflip filter before merging it back with the other stream by
-overlaying it on top. You can use the following command to achieve this:
-
The result will be that in output the top half of the video is mirrored
-onto the bottom half.
-
-
Video filters are loaded using the -vf option passed to
-ffmpeg or to ffplay. Filters in the same linear
-chain are separated by commas. In our example, split, fifo,
-overlay are in one linear chain, and fifo, crop, vflip are in
-another. The points where the linear chains join are labeled by names
-enclosed in square brackets. In our example, that is [T1] and
-[T2]. The magic labels [in] and [out] are the points
-where video is input and output.
-
-
Some filters take in input a list of parameters: they are specified
-after the filter name and an equal sign, and are separated each other
-by a semicolon.
-
-
There exist so-called source filters that do not have a video
-input, and we expect in the future some sink filters that will
-not have video output.
-
The ‘graph2dot’ program included in the FFmpeg ‘tools’
-directory can be used to parse a filter graph description and issue a
-corresponding textual representation in the dot language.
-
-
Invoke the command:
-
graph2dot -h
-
-
-
to see how to use ‘graph2dot’.
-
-
You can then pass the dot description to the ‘dot’ program (from
-the graphviz suite of programs) and obtain a graphical representation
-of the filter graph.
-
A filtergraph is a directed graph of connected filters. It can contain
-cycles, and there can be multiple links between a pair of
-filters. Each link has one input pad on one side connecting it to one
-filter from which it takes its input, and one output pad on the other
-side connecting it to the one filter accepting its output.
-
-
Each filter in a filtergraph is an instance of a filter class
-registered in the application, which defines the features and the
-number of input and output pads of the filter.
-
-
A filter with no input pads is called a "source", a filter with no
-output pads is called a "sink".
-
A filtergraph can be represented using a textual representation, which
-is recognized by the -vf option of the ff*
-tools, and by the avfilter_graph_parse() function defined in
-‘libavfilter/avfiltergraph.h’.
-
-
A filterchain consists of a sequence of connected filters, each one
-connected to the previous one in the sequence. A filterchain is
-represented by a list of ","-separated filter descriptions.
-
-
A filtergraph consists of a sequence of filterchains. A sequence of
-filterchains is represented by a list of ";"-separated filterchain
-descriptions.
-
-
A filter is represented by a string of the form:
-[in_link_1]...[in_link_N]filter_name=arguments[out_link_1]...[out_link_M]
-
-
filter_name is the name of the filter class of which the
-described filter is an instance of, and has to be the name of one of
-the filter classes registered in the program.
-The name of the filter class is optionally followed by a string
-"=arguments".
-
-
arguments is a string which contains the parameters used to
-initialize the filter instance, and are described in the filter
-descriptions below.
-
-
The list of arguments can be quoted using the character "’" as initial
-and ending mark, and the character ’\’ for escaping the characters
-within the quoted text; otherwise the argument string is considered
-terminated when the next special character (belonging to the set
-"[]=;,") is encountered.
-
-
The name and arguments of the filter are optionally preceded and
-followed by a list of link labels.
-A link label allows to name a link and associate it to a filter output
-or input pad. The preceding labels in_link_1
-... in_link_N, are associated to the filter input pads,
-the following labels out_link_1 ... out_link_M, are
-associated to the output pads.
-
-
When two link labels with the same name are found in the
-filtergraph, a link between the corresponding input and output pad is
-created.
-
-
If an output pad is not labelled, it is linked by default to the first
-unlabelled input pad of the next filter in the filterchain.
-For example in the filterchain:
-
nullsrc, split[L1], [L2]overlay, nullsink
-
-
the split filter instance has two output pads, and the overlay filter
-instance two input pads. The first output pad of split is labelled
-"L1", the first input pad of overlay is labelled "L2", and the second
-output pad of split is linked to the second input pad of overlay,
-which are both unlabelled.
-
-
In a complete filterchain all the unlabelled filter input and output
-pads must be connected. A filtergraph is considered valid if all the
-filter input and output pads of all the filterchains are connected.
-
-
Follows a BNF description for the filtergraph syntax:
-
NAME ::= sequence of alphanumeric characters and '_'
-LINKLABEL ::= "[" NAME "]"
-LINKLABELS ::= LINKLABEL [LINKLABELS]
-FILTER_ARGUMENTS ::= sequence of chars (eventually quoted)
-FILTER ::= [LINKNAMES] NAME ["=" ARGUMENTS] [LINKNAMES]
-FILTERCHAIN ::= FILTER [,FILTERCHAIN]
-FILTERGRAPH ::= FILTERCHAIN [;FILTERGRAPH]
-
When you configure your FFmpeg build, you can disable any of the
-existing filters using --disable-filters.
-The configure output will show the audio filters included in your
-build.
-
-
Below is a description of the currently available audio filters.
-
Merge two audio streams into a single multi-channel stream.
-
-
This filter does not need any argument.
-
-
If the channel layouts of the inputs are disjoint, and therefore compatible,
-the channel layout of the output will be set accordingly and the channels
-will be reordered as necessary. If the channel layouts of the inputs are not
-disjoint, the output will have all the channels of the first input then all
-the channels of the second input, in that order, and the channel layout of
-the output will be the default value corresponding to the total number of
-channels.
-
-
For example, if the first input is in 2.1 (FL+FR+LF) and the second input
-is FC+BL+BR, then the output will be in 5.1, with the channels in the
-following order: a1, a2, b1, a3, b2, b3 (a1 is the first channel of the
-first input, b1 is the first channel of the second input).
-
-
On the other hand, if both input are in stereo, the output channels will be
-in the default order: a1, a2, b1, b2, and the channel layout will be
-arbitrarily set to 4.0, which may or may not be the expected value.
-
-
Both inputs must have the same sample rate, format and packing.
-
-
If inputs do not have the same duration, the output will stop with the
-shortest.
-
-
Example: merge two mono files into a stereo stream:
-
Resample the input audio to the specified sample rate.
-
-
The filter accepts exactly one parameter, the output sample rate. If not
-specified then the filter will automatically convert between its input
-and output sample rates.
-
-
For example, to resample the input audio to 44100Hz:
-
Show a line containing various information for each input audio frame.
-The input audio is not modified.
-
-
The shown line contains a sequence of key/value pairs of the form
-key:value.
-
-
A description of each shown parameter follows:
-
-
-
‘n’
-
sequential number of the input frame, starting from 0
-
-
-
‘pts’
-
presentation TimeStamp of the input frame, expressed as a number of
-time base units. The time base unit depends on the filter input pad, and
-is usually 1/sample_rate.
-
-
-
‘pts_time’
-
presentation TimeStamp of the input frame, expressed as a number of
-seconds
-
-
-
‘pos’
-
position of the frame in the input stream, -1 if this information in
-unavailable and/or meaningless (for example in case of synthetic audio)
-
-
-
‘fmt’
-
sample format name
-
-
-
‘chlayout’
-
channel layout description
-
-
-
‘nb_samples’
-
number of samples (per each channel) contained in the filtered frame
-
-
-
‘rate’
-
sample rate for the audio frame
-
-
-
‘planar’
-
if the packing format is planar, 0 if packed
-
-
-
‘checksum’
-
Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame
-
-
-
‘plane_checksum’
-
Adler-32 checksum (printed in hexadecimal) for each input frame plane,
-expressed in the form "[c0c1c2c3c4c5
-c6c7]"
-
Forward two audio streams and control the order the buffers are forwarded.
-
-
The argument to the filter is an expression deciding which stream should be
-forwarded next: if the result is negative, the first stream is forwarded; if
-the result is positive or zero, the second stream is forwarded. It can use
-the following variables:
-
-
-
b1 b2
-
number of buffers forwarded so far on each stream
-
-
s1 s2
-
number of samples forwarded so far on each stream
-
-
t1 t2
-
current timestamp of each stream
-
-
-
-
The default value is t1-t2, which means to always forward the stream
-that has a smaller timestamp.
-
-
Example: stress-test amerge by randomly sending buffers on the wrong
-input, while avoiding too much of a desynchronization:
-
This filter adds ‘cues’ to 44.1kHz stereo (i.e. audio CD format) audio
-so that when listened to on headphones the stereo image is moved from
-inside your head (standard for headphones) to outside and in front of
-the listener (standard for speakers).
-
Mix channels with specific gain levels. The filter accepts the output
-channel layout followed by a set of channels definitions.
-
-
This filter is also designed to remap efficiently the channels of an audio
-stream.
-
-
The filter accepts parameters of the form:
-"l:outdef:outdef:..."
-
-
-
‘l’
-
output channel layout or number of channels
-
-
-
‘outdef’
-
output channel specification, of the form:
-"out_name=[gain*]in_name[+[gain*]in_name...]"
-
-
-
‘out_name’
-
output channel to define, either a channel name (FL, FR, etc.) or a channel
-number (c0, c1, etc.)
-
-
-
‘gain’
-
multiplicative coefficient for the channel, 1 leaving the volume unchanged
-
-
-
‘in_name’
-
input channel to use, see out_name for details; it is not possible to mix
-named and numbered input channels
-
-
-
-
If the ‘=’ in a channel specification is replaced by ‘<’, then the gains for
-that specification will be renormalized so that the total is 1, thus
-avoiding clipping noise.
-
Note that ffmpeg integrates a default down-mix (and up-mix) system
-that should be preferred (see "-ac" option) unless you have very specific
-needs.
-
The channel remapping will be effective if, and only if:
-
-
-
gain coefficients are zeroes or ones,
-
only one input per channel output,
-
the number of output channels is supported by libswresample (16 at the
- moment)
-
-
-
If all these conditions are satisfied, the filter will notify the user ("Pure
-channel mapping detected"), and use an optimized and lossless method to do the
-remapping.
-
-
For example, if you have a 5.1 source and want a stereo audio stream by
-dropping the extra channels:
-
pan="stereo: c0=FL : c1=FR"
-
-
-
Given the same source, you can also switch front left and front right channels
-and keep the input channel layout:
-
This filter logs a message when it detects that the input audio volume is less
-or equal to a noise tolerance value for a duration greater or equal to the
-minimum detected noise duration.
-
-
The printed times and duration are expressed in seconds.
-
-
-
‘duration, d’
-
Set silence duration until notification (default is 2 seconds).
-
-
-
‘noise, n’
-
Set noise tolerance. Can be specified in dB (in case "dB" is appended to the
-specified value) or amplitude ratio. Default is -60dB, or 0.001.
-
-
-
-
Detect 5 seconds of silence with -50dB noise tolerance:
-
silencedetect=n=-50dB:d=5
-
-
-
Complete example with ffmpeg to detect silence with 0.0001 noise
-tolerance in ‘silence.mp3’:
-
The filter accepts exactly one parameter vol, which expresses
-how the audio volume will be increased or decreased.
-
-
Output values are clipped to the maximum value.
-
-
If vol is expressed as a decimal number, the output audio
-volume is given by the relation:
-
output_volume = vol * input_volume
-
-
-
If vol is expressed as a decimal number followed by the string
-"dB", the value represents the requested change in decibels of the
-input audio power, and the output audio volume is given by the
-relation:
-
output_volume = 10^(vol/20) * input_volume
-
-
-
Otherwise vol is considered an expression and its evaluated
-value is used for computing the output audio volume according to the
-first relation.
-
Buffer audio frames, and make them available to the filter chain.
-
-
This source is mainly intended for a programmatic use, in particular
-through the interface defined in ‘libavfilter/asrc_abuffer.h’.
-
-
It accepts the following mandatory parameters:
-sample_rate:sample_fmt:channel_layout:packing
-
-
-
‘sample_rate’
-
The sample rate of the incoming audio buffers.
-
-
-
‘sample_fmt’
-
The sample format of the incoming audio buffers.
-Either a sample format name or its corresponging integer representation from
-the enum AVSampleFormat in ‘libavutil/samplefmt.h’
-
-
-
‘channel_layout’
-
The channel layout of the incoming audio buffers.
-Either a channel layout name from channel_layout_map in
-‘libavutil/audioconvert.c’ or its corresponding integer representation
-from the AV_CH_LAYOUT_* macros in ‘libavutil/audioconvert.h’
-
-
-
‘packing’
-
Either "packed" or "planar", or their integer representation: 0 or 1
-respectively.
-
-
-
-
-
For example:
-
abuffer=44100:s16:stereo:planar
-
-
-
will instruct the source to accept planar 16bit signed stereo at 44100Hz.
-Since the sample format with name "s16" corresponds to the number
-1 and the "stereo" channel layout corresponds to the value 3, this is
-equivalent to:
-
Generate an audio signal specified by an expression.
-
-
This source accepts in input one or more expressions (one for each
-channel), which are evaluated and used to generate a corresponding
-audio signal.
-
-
It accepts the syntax: exprs[::options].
-exprs is a list of expressions separated by ":", one for each
-separate channel. The output channel layout depends on the number of
-provided expressions, up to 8 channels are supported.
-
-
options is an optional sequence of key=value pairs,
-separated by ":".
-
-
The description of the accepted options follows.
-
-
-
‘duration, d’
-
Set the minimum duration of the sourced audio. See the function
-av_parse_time() for the accepted format.
-Note that the resulting duration may be greater than the specified
-duration, as the generated audio is always cut at the end of a
-complete frame.
-
-
If not specified, or the expressed duration is negative, the audio is
-supposed to be generated forever.
-
-
-
‘nb_samples, n’
-
Set the number of samples per channel per each output frame,
-default to 1024.
-
-
-
‘sample_rate, s’
-
Specify the sample rate, default to 44100.
-
-
-
-
Each expression in exprs can contain the following constants:
-
-
-
‘n’
-
number of the evaluated sample, starting from 0
-
-
-
‘t’
-
time of the evaluated sample expressed in seconds, starting from 0
-
It accepts the syntax: movie_name[:options] where
-movie_name is the name of the resource to read (not necessarily
-a file but also a device or a stream accessed through some protocol),
-and options is an optional sequence of key=value
-pairs, separated by ":".
-
-
The description of the accepted options follows.
-
-
-
‘format_name, f’
-
Specify the format assumed for the movie to read, and can be either
-the name of a container or an input device. If not specified the
-format is guessed from movie_name or by probing.
-
-
-
‘seek_point, sp’
-
Specify the seek point in seconds, the frames will be output
-starting from this seek point, the parameter is evaluated with
-av_strtod so the numerical value may be suffixed by an IS
-postfix. Default value is "0".
-
-
-
‘stream_index, si’
-
Specify the index of the audio stream to read. If the value is -1,
-the best suited audio stream will be automatically selected. Default
-value is "-1".
-
Null audio source, return unprocessed audio frames. It is mainly useful
-as a template and to be employed in analysis / debugging tools, or as
-the source for filters which ignore the input data (for example the sox
-synth filter).
-
-
It accepts an optional sequence of key=value pairs,
-separated by ":".
-
-
The description of the accepted options follows.
-
-
-
‘sample_rate, s’
-
Specify the sample rate, and defaults to 44100.
-
-
-
‘channel_layout, cl’
-
-
Specify the channel layout, and can be either an integer or a string
-representing a channel layout. The default value of channel_layout
-is "stereo".
-
-
Check the channel_layout_map definition in
-‘libavcodec/audioconvert.c’ for the mapping between strings and
-channel layout values.
-
-
-
‘nb_samples, n’
-
Set the number of samples per requested frames.
-
-
-
-
-
Follow some examples:
-
# set the sample rate to 48000 Hz and the channel layout to AV_CH_LAYOUT_MONO.
-anullsrc=r=48000:cl=4
-
-# same as
-anullsrc=r=48000:cl=mono
-
Buffer audio frames, and make them available to the end of filter chain.
-
-
This sink is mainly intended for programmatic use, in particular
-through the interface defined in ‘libavfilter/buffersink.h’.
-
-
It requires a pointer to an AVABufferSinkContext structure, which
-defines the incoming buffers’ formats, to be passed as the opaque
-parameter to avfilter_init_filter for initialization.
-
When you configure your FFmpeg build, you can disable any of the
-existing filters using --disable-filters.
-The configure output will show the video filters included in your
-build.
-
-
Below is a description of the currently available video filters.
-
Detect frames that are (almost) completely black. Can be useful to
-detect chapter transitions or commercials. Output lines consist of
-the frame number of the detected frame, the percentage of blackness,
-the position in the file if known or -1 and the timestamp in seconds.
-
-
In order to display the output lines, you need to set the loglevel at
-least to the AV_LOG_INFO value.
-
-
The filter accepts the syntax:
-
blackframe[=amount:[threshold]]
-
-
-
amount is the percentage of the pixels that have to be below the
-threshold, and defaults to 98.
-
-
threshold is the threshold below which a pixel value is
-considered black, and defaults to 32.
-
This filter accepts the parameters:
-luma_radius:luma_power:chroma_radius:chroma_power:alpha_radius:alpha_power
-
-
Chroma and alpha parameters are optional, if not specified they default
-to the corresponding values set for luma_radius and
-luma_power.
-
-
luma_radius, chroma_radius, and alpha_radius represent
-the radius in pixels of the box used for blurring the corresponding
-input plane. They are expressions, and can contain the following
-constants:
-
-
‘w, h’
-
the input width and height in pixels
-
-
-
‘cw, ch’
-
the input chroma image width and height in pixels
-
-
-
‘hsub, vsub’
-
horizontal and vertical chroma subsample values. For example for the
-pixel format "yuv422p" hsub is 2 and vsub is 1.
-
-
-
-
The radius must be a non-negative number, and must not be greater than
-the value of the expression min(w,h)/2 for the luma and alpha planes,
-and of min(cw,ch)/2 for the chroma planes.
-
-
luma_power, chroma_power, and alpha_power represent
-how many times the boxblur filter is applied to the corresponding
-plane.
-
-
Some examples follow:
-
-
-
-Apply a boxblur filter with luma, chroma, and alpha radius
-set to 2:
-
boxblur=2:1
-
-
-
-Set luma radius to 2, alpha and chroma radius to 0
-
boxblur=2:1:0:0:0:0
-
-
-
-Set luma and chroma radius to a fraction of the video dimension
-
The parameters are expressions containing the following constants:
-
-
-
‘x, y’
-
the computed values for x and y. They are evaluated for
-each new frame.
-
-
-
‘in_w, in_h’
-
the input width and height
-
-
-
‘iw, ih’
-
same as in_w and in_h
-
-
-
‘out_w, out_h’
-
the output (cropped) width and height
-
-
-
‘ow, oh’
-
same as out_w and out_h
-
-
-
‘a’
-
same as iw / ih
-
-
-
‘sar’
-
input sample aspect ratio
-
-
-
‘dar’
-
input display aspect ratio, it is the same as (iw / ih) * sar
-
-
-
‘hsub, vsub’
-
horizontal and vertical chroma subsample values. For example for the
-pixel format "yuv422p" hsub is 2 and vsub is 1.
-
-
-
‘n’
-
the number of input frame, starting from 0
-
-
-
‘pos’
-
the position in the file of the input frame, NAN if unknown
-
-
-
‘t’
-
timestamp expressed in seconds, NAN if the input timestamp is unknown
-
-
-
-
-
The out_w and out_h parameters specify the expressions for
-the width and height of the output (cropped) video. They are
-evaluated just at the configuration of the filter.
-
-
The default value of out_w is "in_w", and the default value of
-out_h is "in_h".
-
-
The expression for out_w may depend on the value of out_h,
-and the expression for out_h may depend on out_w, but they
-cannot depend on x and y, as x and y are
-evaluated after out_w and out_h.
-
-
The x and y parameters specify the expressions for the
-position of the top-left corner of the output (non-cropped) area. They
-are evaluated for each frame. If the evaluated value is not valid, it
-is approximated to the nearest valid value.
-
-
The default value of x is "(in_w-out_w)/2", and the default
-value for y is "(in_h-out_h)/2", which set the cropped area at
-the center of the input image.
-
-
The expression for x may depend on y, and the expression
-for y may depend on x.
-
-
Follow some examples:
-
# crop the central input area with size 100x100
-crop=100:100
-
-# crop the central input area with size 2/3 of the input video
-"crop=2/3*in_w:2/3*in_h"
-
-# crop the input video central square
-crop=in_h
-
-# delimit the rectangle with the top-left corner placed at position
-# 100:100 and the right-bottom corner corresponding to the right-bottom
-# corner of the input image.
-crop=in_w-100:in_h-100:100:100
-
-# crop 10 pixels from the left and right borders, and 20 pixels from
-# the top and bottom borders
-"crop=in_w-2*10:in_h-2*20"
-
-# keep only the bottom right quarter of the input image
-"crop=in_w/2:in_h/2:in_w/2:in_h/2"
-
-# crop height for getting Greek harmony
-"crop=in_w:1/PHI*in_w"
-
-# trembling effect
-"crop=in_w/2:in_h/2:(in_w-out_w)/2+((in_w-out_w)/2)*sin(n/10):(in_h-out_h)/2 +((in_h-out_h)/2)*sin(n/7)"
-
-# erratic camera effect depending on timestamp
-"crop=in_w/2:in_h/2:(in_w-out_w)/2+((in_w-out_w)/2)*sin(t*10):(in_h-out_h)/2 +((in_h-out_h)/2)*sin(t*13)"
-
-# set x depending on the value of y
-"crop=in_w/2:in_h/2:y:10+10*sin(n/10)"
-
Calculate necessary cropping parameters and prints the recommended
-parameters through the logging system. The detected dimensions
-correspond to the non-black area of the input video.
-
-
It accepts the syntax:
-
cropdetect[=limit[:round[:reset]]]
-
-
-
-
‘limit’
-
Threshold, which can be optionally specified from nothing (0) to
-everything (255), defaults to 24.
-
-
-
‘round’
-
Value which the width/height should be divisible by, defaults to
-16. The offset is automatically adjusted to center the video. Use 2 to
-get only even dimensions (needed for 4:2:2 video). 16 is best when
-encoding to most video codecs.
-
-
-
‘reset’
-
Counter that determines after how many frames cropdetect will reset
-the previously detected largest video area and start over to detect
-the current optimal crop area. Defaults to 0.
-
-
This can be useful when channel logos distort the video area. 0
-indicates never reset and return the largest area encountered during
-playback.
-
Suppress a TV station logo by a simple interpolation of the surrounding
-pixels. Just set a rectangle covering the logo and watch it disappear
-(and sometimes something even uglier appear - your mileage may vary).
-
-
The filter accepts parameters as a string of the form
-"x:y:w:h:band", or as a list of
-key=value pairs, separated by ":".
-
-
The description of the accepted parameters follows.
-
-
-
‘x, y’
-
Specify the top left corner coordinates of the logo. They must be
-specified.
-
-
-
‘w, h’
-
Specify the width and height of the logo to clear. They must be
-specified.
-
-
-
‘band, t’
-
Specify the thickness of the fuzzy edge of the rectangle (added to
-w and h). The default value is 4.
-
-
-
‘show’
-
When set to 1, a green rectangle is drawn on the screen to simplify
-finding the right x, y, w, h parameters, and
-band is set to 4. The default value is 0.
-
-
-
-
-
Some examples follow.
-
-
-
-Set a rectangle covering the area with top left corner coordinates 0,0
-and size 100x77, setting a band of size 10:
-
delogo=0:0:100:77:10
-
-
-
-As the previous example, but use named options:
-
Attempt to fix small changes in horizontal and/or vertical shift. This
-filter helps remove camera shake from hand-holding a camera, bumping a
-tripod, moving on a vehicle, etc.
-
-
The filter accepts parameters as a string of the form
-"x:y:w:h:rx:ry:edge:blocksize:contrast:search:filename"
-
-
A description of the accepted parameters follows.
-
-
-
‘x, y, w, h’
-
Specify a rectangular area where to limit the search for motion
-vectors.
-If desired the search for motion vectors can be limited to a
-rectangular area of the frame defined by its top left corner, width
-and height. These parameters have the same meaning as the drawbox
-filter which can be used to visualise the position of the bounding
-box.
-
-
This is useful when simultaneous movement of subjects within the frame
-might be confused for camera motion by the motion vector search.
-
-
If any or all of x, y, w and h are set to -1
-then the full frame is used. This allows later options to be set
-without specifying the bounding box for the motion vector search.
-
-
Default - search the whole frame.
-
-
-
‘rx, ry’
-
Specify the maximum extent of movement in x and y directions in the
-range 0-64 pixels. Default 16.
-
-
-
‘edge’
-
Specify how to generate pixels to fill blanks at the edge of the
-frame. An integer from 0 to 3 as follows:
-
-
‘0’
-
Fill zeroes at blank locations
-
-
‘1’
-
Original image at blank locations
-
-
‘2’
-
Extruded edge value at blank locations
-
-
‘3’
-
Mirrored edge at blank locations
-
-
-
-
The default setting is mirror edge at blank locations.
-
-
-
‘blocksize’
-
Specify the blocksize to use for motion search. Range 4-128 pixels,
-default 8.
-
-
-
‘contrast’
-
Specify the contrast threshold for blocks. Only blocks with more than
-the specified contrast (difference between darkest and lightest
-pixels) will be considered. Range 1-255, default 125.
-
-
-
‘search’
-
Specify the search strategy 0 = exhaustive search, 1 = less exhaustive
-search. Default - exhaustive search.
-
-
-
‘filename’
-
If set then a detailed log of the motion search is written to the
-specified file.
-
Draw text string or text from specified file on top of video using the
-libfreetype library.
-
-
To enable compilation of this filter you need to configure FFmpeg with
---enable-libfreetype.
-
-
The filter also recognizes strftime() sequences in the provided text
-and expands them accordingly. Check the documentation of strftime().
-
-
The filter accepts parameters as a list of key=value pairs,
-separated by ":".
-
-
The description of the accepted parameters follows.
-
-
-
‘fontfile’
-
The font file to be used for drawing text. Path must be included.
-This parameter is mandatory.
-
-
-
‘text’
-
The text string to be drawn. The text must be a sequence of UTF-8
-encoded characters.
-This parameter is mandatory if no file is specified with the parameter
-textfile.
-
-
-
‘textfile’
-
A text file containing text to be drawn. The text must be a sequence
-of UTF-8 encoded characters.
-
-
This parameter is mandatory if no text string is specified with the
-parameter text.
-
-
If both text and textfile are specified, an error is thrown.
-
-
-
‘x, y’
-
The expressions which specify the offsets where text will be drawn
-within the video frame. They are relative to the top/left border of the
-output image.
-
-
The default value of x and y is "0".
-
-
See below for the list of accepted constants.
-
-
-
‘fontsize’
-
The font size to be used for drawing text.
-The default value of fontsize is 16.
-
-
-
‘fontcolor’
-
The color to be used for drawing fonts.
-Either a string (e.g. "red") or in 0xRRGGBB[AA] format
-(e.g. "0xff000033"), possibly followed by an alpha specifier.
-The default value of fontcolor is "black".
-
-
-
‘boxcolor’
-
The color to be used for drawing box around text.
-Either a string (e.g. "yellow") or in 0xRRGGBB[AA] format
-(e.g. "0xff00ff"), possibly followed by an alpha specifier.
-The default value of boxcolor is "white".
-
-
-
‘box’
-
Used to draw a box around text using background color.
-Value should be either 1 (enable) or 0 (disable).
-The default value of box is 0.
-
-
-
‘shadowx, shadowy’
-
The x and y offsets for the text shadow position with respect to the
-position of the text. They can be either positive or negative
-values. Default value for both is "0".
-
-
-
‘shadowcolor’
-
The color to be used for drawing a shadow behind the drawn text. It
-can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA]
-form (e.g. "0xff00ff"), possibly followed by an alpha specifier.
-The default value of shadowcolor is "black".
-
-
-
‘ft_load_flags’
-
Flags to be used for loading the fonts.
-
-
The flags map the corresponding flags supported by libfreetype, and are
-a combination of the following values:
-
-
default
-
no_scale
-
no_hinting
-
render
-
no_bitmap
-
vertical_layout
-
force_autohint
-
crop_bitmap
-
pedantic
-
ignore_global_advance_width
-
no_recurse
-
ignore_transform
-
monochrome
-
linear_design
-
no_autohint
-
end table
-
-
-
Default value is "render".
-
-
For more information consult the documentation for the FT_LOAD_*
-libfreetype flags.
-
-
-
‘tabsize’
-
The size in number of spaces to use for rendering the tab.
-Default value is 4.
-
-
-
-
The parameters for x and y are expressions containing the
-following constants:
-
-
-
‘W, H’
-
the input width and height
-
-
-
‘tw, text_w’
-
the width of the rendered text
-
-
-
‘th, text_h’
-
the height of the rendered text
-
-
-
‘lh, line_h’
-
the height of each text line
-
-
-
‘sar’
-
input sample aspect ratio
-
-
-
‘dar’
-
input display aspect ratio, it is the same as (w / h) * sar
-
-
-
‘hsub, vsub’
-
horizontal and vertical chroma subsample values. For example for the
-pixel format "yuv422p" hsub is 2 and vsub is 1.
-
-
-
‘max_glyph_w’
-
maximum glyph width, that is the maximum width for all the glyphs
-contained in the rendered text
-
-
-
‘max_glyph_h’
-
maximum glyph height, that is the maximum height for all the glyphs
-contained in the rendered text, it is equivalent to ascent -
-descent.
-
-
-
‘max_glyph_a, ascent’
-
-
the maximum distance from the baseline to the highest/upper grid
-coordinate used to place a glyph outline point, for all the rendered
-glyphs.
-It is a positive value, due to the grid’s orientation with the Y axis
-upwards.
-
-
-
‘max_glyph_d, descent’
-
the maximum distance from the baseline to the lowest grid coordinate
-used to place a glyph outline point, for all the rendered glyphs.
-This is a negative value, due to the grid’s orientation, with the Y axis
-upwards.
-
-
-
‘n’
-
the number of input frame, starting from 0
-
-
-
‘t’
-
timestamp expressed in seconds, NAN if the input timestamp is unknown
-
-
-
‘timecode’
-
initial timecode representation in "hh:mm:ss[:;.]ff" format. It can be used
-with or without text parameter. rate option must be specified.
-Note that timecode options are not effective if FFmpeg is build with
---disable-avcodec.
-
-
-
‘r, rate’
-
frame rate (timecode only)
-
-
-
-
Some examples follow.
-
-
-
-Draw "Test Text" with font FreeSerif, using the default values for the
-optional parameters.
-
-
-Draw ’Test Text’ with font FreeSerif of size 24 at position x=100
-and y=50 (counting from the top-left corner of the screen), text is
-yellow with a red box around it. Both the text and the box have an
-opacity of 20%.
-
-
-Show a text line sliding from right to left in the last row of the video
-frame. The file ‘LONG_LINE’ is assumed to contain a single line
-with no newlines.
-
It accepts the parameters:
-type:start_frame:nb_frames[:options]
-
-
type specifies if the effect type, can be either "in" for
-fade-in, or "out" for a fade-out effect.
-
-
start_frame specifies the number of the start frame for starting
-to apply the fade effect.
-
-
nb_frames specifies the number of frames for which the fade
-effect has to last. At the end of the fade-in effect the output video
-will have the same intensity as the input video, at the end of the
-fade-out transition the output video will be completely black.
-
-
options is an optional sequence of key=value pairs,
-separated by ":". The description of the accepted options follows.
-
-
-
‘type, t’
-
See type.
-
-
-
‘start_frame, s’
-
See start_frame.
-
-
-
‘nb_frames, n’
-
See nb_frames.
-
-
-
‘alpha’
-
If set to 1, fade only alpha channel, if one exists on the input.
-Default value is 0.
-
-
-
-
A few usage examples follow, usable too as test scenarios.
-
# fade in first 30 frames of video
-fade=in:0:30
-
-# fade out last 45 frames of a 200-frame video
-fade=out:155:45
-
-# fade in first 25 frames and fade out last 25 frames of a 1000-frame video
-fade=in:0:25, fade=out:975:25
-
-# make first 5 frames black, then fade in from frame 5-24
-fade=in:5:20
-
-# fade in alpha over first 25 frames of video
-fade=in:0:25:alpha=1
-
It accepts one parameter which specifies the required field order that
-the input interlaced video will be transformed to. The parameter can
-assume one of the following values:
-
-
-
‘0 or bff’
-
output bottom field first
-
-
‘1 or tff’
-
output top field first
-
-
-
-
Default value is "tff".
-
-
Transformation is achieved by shifting the picture content up or down
-by one line, and filling the remaining line with appropriate picture content.
-This method is consistent with most broadcast field order converters.
-
-
If the input video is not flagged as being interlaced, or it is already
-flagged as being of the required output field order then this filter does
-not alter the incoming video.
-
-
This filter is very useful when converting to or from PAL DV material,
-which is bottom field first.
-
Convert the input video to one of the specified pixel formats.
-Libavfilter will try to pick one that is supported for the input to
-the next filter.
-
-
The filter accepts a list of pixel format names, separated by ":",
-for example "yuv420p:monow:rgb24".
-
-
Some examples follow:
-
# convert the input video to the format "yuv420p"
-format=yuv420p
-
-# convert the input video to any of the formats in the list
-format=yuv420p:yuv444p:yuv410p
-
To enable compilation of this filter you need to install the frei0r
-header and configure FFmpeg with --enable-frei0r.
-
-
The filter supports the syntax:
-
filter_name[{:|=}param1:param2:...:paramN]
-
-
-
filter_name is the name to the frei0r effect to load. If the
-environment variable FREI0R_PATH is defined, the frei0r effect
-is searched in each one of the directories specified by the colon
-separated list in FREIOR_PATH, otherwise in the standard frei0r
-paths, which are in this order: ‘HOME/.frei0r-1/lib/’,
-‘/usr/local/lib/frei0r-1/’, ‘/usr/lib/frei0r-1/’.
-
-
param1, param2, ... , paramN specify the parameters
-for the frei0r effect.
-
-
A frei0r effect parameter can be a boolean (whose values are specified
-with "y" and "n"), a double, a color (specified by the syntax
-R/G/B, R, G, and B being float
-numbers from 0.0 to 1.0) or by an av_parse_color() color
-description), a position (specified by the syntax X/Y,
-X and Y being float numbers) and a string.
-
-
The number and kind of parameters depend on the loaded effect. If an
-effect parameter is not specified the default value is set.
-
-
Some examples follow:
-
# apply the distort0r effect, set the first two double parameters
-frei0r=distort0r:0.5:0.01
-
-# apply the colordistance effect, takes a color as first parameter
-frei0r=colordistance:0.2/0.3/0.4
-frei0r=colordistance:violet
-frei0r=colordistance:0x112233
-
-# apply the perspective effect, specify the top left and top right
-# image positions
-frei0r=perspective:0.2/0.2:0.8/0.2
-
Fix the banding artifacts that are sometimes introduced into nearly flat
-regions by truncation to 8bit color depth.
-Interpolate the gradients that should go where the bands are, and
-dither them.
-
-
This filter is designed for playback only. Do not use it prior to
-lossy compression, because compression tends to lose the dither and
-bring back the bands.
-
-
The filter takes two optional parameters, separated by ’:’:
-strength:radius
-
-
strength is the maximum amount by which the filter will change
-any one pixel. Also the threshold for detecting nearly flat
-regions. Acceptable values range from .51 to 255, default value is
-1.2, out-of-range values will be clipped to the valid range.
-
-
radius is the neighborhood to fit the gradient to. A larger
-radius makes for smoother gradients, but also prevents the filter from
-modifying the pixels near detailed regions. Acceptable values are
-8-32, default value is 16, out-of-range values will be clipped to the
-valid range.
-
High precision/quality 3d denoise filter. This filter aims to reduce
-image noise producing smooth images and making still images really
-still. It should enhance compressibility.
-
-
It accepts the following optional parameters:
-luma_spatial:chroma_spatial:luma_tmp:chroma_tmp
-
-
-
‘luma_spatial’
-
a non-negative float number which specifies spatial luma strength,
-defaults to 4.0
-
-
-
‘chroma_spatial’
-
a non-negative float number which specifies spatial chroma strength,
-defaults to 3.0*luma_spatial/4.0
-
-
-
‘luma_tmp’
-
a float number which specifies luma temporal strength, defaults to
-6.0*luma_spatial/4.0
-
-
-
‘chroma_tmp’
-
a float number which specifies chroma temporal strength, defaults to
-luma_tmp*chroma_spatial/luma_spatial
-
Compute a look-up table for binding each pixel component input value
-to an output value, and apply it to input video.
-
-
lutyuv applies a lookup table to a YUV input video, lutrgb
-to an RGB input video.
-
-
These filters accept in input a ":"-separated list of options, which
-specify the expressions used for computing the lookup table for the
-corresponding pixel component values.
-
-
The lut filter requires either YUV or RGB pixel formats in
-input, and accepts the options:
-
-
‘c0’
-
first pixel component
-
-
‘c1’
-
second pixel component
-
-
‘c2’
-
third pixel component
-
-
‘c3’
-
fourth pixel component, corresponds to the alpha component
-
-
-
-
The exact component associated to each option depends on the format in
-input.
-
-
The lutrgb filter requires RGB pixel formats in input, and
-accepts the options:
-
-
‘r’
-
red component
-
-
‘g’
-
green component
-
-
‘b’
-
blue component
-
-
‘a’
-
alpha component
-
-
-
-
The lutyuv filter requires YUV pixel formats in input, and
-accepts the options:
-
-
‘y’
-
Y/luminance component
-
-
‘u’
-
U/Cb component
-
-
‘v’
-
V/Cr component
-
-
‘a’
-
alpha component
-
-
-
-
The expressions can contain the following constants and functions:
-
-
-
‘w, h’
-
the input width and height
-
-
-
‘val’
-
input value for the pixel component
-
-
-
‘clipval’
-
the input value clipped in the minval-maxval range
-
-
-
‘maxval’
-
maximum value for the pixel component
-
-
-
‘minval’
-
minimum value for the pixel component
-
-
-
‘negval’
-
the negated value for the pixel component value clipped in the
-minval-maxval range , it corresponds to the expression
-"maxval-clipval+minval"
-
-
-
‘clip(val)’
-
the computed value in val clipped in the
-minval-maxval range
-
-
-
‘gammaval(gamma)’
-
the computed gamma correction value of the pixel component value
-clipped in the minval-maxval range, corresponds to the
-expression
-"pow((clipval-minval)/(maxval-minval)\,gamma)*(maxval-minval)+minval"
-
-
-
-
-
All expressions default to "val".
-
-
Some examples follow:
-
# negate input video
-lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
-lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
-
-# the above is the same as
-lutrgb="r=negval:g=negval:b=negval"
-lutyuv="y=negval:u=negval:v=negval"
-
-# negate luminance
-lutyuv=y=negval
-
-# remove chroma components, turns the video into a graytone image
-lutyuv="u=128:v=128"
-
-# apply a luma burning effect
-lutyuv="y=2*val"
-
-# remove green and blue components
-lutrgb="g=0:b=0"
-
-# set a constant alpha channel value on input
-format=rgba,lutrgb=a="maxval-minval/2"
-
-# correct luminance gamma by a 0.5 factor
-lutyuv=y=gammaval(0.5)
-
This filter provides a wrapper around most of the filters of
-MPlayer/MEncoder.
-
-
This wrapper is considered experimental. Some of the wrapped filters
-may not work properly and we may drop support for them, as they will
-be implemented natively into FFmpeg. Thus you should avoid
-depending on them when writing portable scripts.
-
-
The filters accepts the parameters:
-filter_name[:=]filter_params
-
-
filter_name is the name of a supported MPlayer filter,
-filter_params is a string containing the parameters accepted by
-the named filter.
-
-
The list of the currently supported filters follows:
-
-
2xsai
-
decimate
-
denoise3d
-
detc
-
dint
-
divtc
-
down3dright
-
dsize
-
eq2
-
eq
-
field
-
fil
-
fixpts
-
framestep
-
fspp
-
geq
-
harddup
-
hqdn3d
-
hue
-
il
-
ilpack
-
ivtc
-
kerndeint
-
mcdeint
-
mirror
-
noise
-
ow
-
palette
-
perspective
-
phase
-
pp7
-
pullup
-
qp
-
rectangle
-
remove-logo
-
rotate
-
sab
-
screenshot
-
smartblur
-
softpulldown
-
softskip
-
spp
-
swapuv
-
telecine
-
tile
-
tinterlace
-
unsharp
-
uspp
-
yuvcsp
-
yvu9
-
-
-
The parameter syntax and behavior for the listed filters are the same
-of the corresponding MPlayer filters. For detailed instructions check
-the "VIDEO FILTERS" section in the MPlayer manual.
-
-
Some examples follow:
-
# remove a logo by interpolating the surrounding pixels
-mp=delogo=200:200:80:20:1
-
-# adjust gamma, brightness, contrast
-mp=eq2=1.0:2:0.5
-
-# tweak hue and saturation
-mp=hue=100:-10
-
Force libavfilter not to use any of the specified pixel formats for the
-input to the next filter.
-
-
The filter accepts a list of pixel format names, separated by ":",
-for example "yuv420p:monow:rgb24".
-
-
Some examples follow:
-
# force libavfilter to use a format different from "yuv420p" for the
-# input to the vflip filter
-noformat=yuv420p,vflip
-
-# convert the input video to any of the formats not contained in the list
-noformat=yuv420p:yuv444p:yuv410p
-
Dilate an image by using a specific structuring element.
-This filter corresponds to the libopencv function cvDilate.
-
-
It accepts the parameters: struct_el:nb_iterations.
-
-
struct_el represents a structuring element, and has the syntax:
-colsxrows+anchor_xxanchor_y/shape
-
-
cols and rows represent the number of columns and rows of
-the structuring element, anchor_x and anchor_y the anchor
-point, and shape the shape for the structuring element, and
-can be one of the values "rect", "cross", "ellipse", "custom".
-
-
If the value for shape is "custom", it must be followed by a
-string of the form "=filename". The file with name
-filename is assumed to represent a binary image, with each
-printable character corresponding to a bright pixel. When a custom
-shape is used, cols and rows are ignored, the number
-or columns and rows of the read file are assumed instead.
-
-
The default value for struct_el is "3x3+0x0/rect".
-
-
nb_iterations specifies the number of times the transform is
-applied to the image, and defaults to 1.
-
-
Follow some example:
-
# use the default values
-ocv=dilate
-
-# dilate using a structuring element with a 5x5 cross, iterate two times
-ocv=dilate=5x5+2x2/cross:2
-
-# read the shape from the file diamond.shape, iterate two times
-# the file diamond.shape may contain a pattern of characters like this:
-# *
-# ***
-# *****
-# ***
-# *
-# the specified cols and rows are ignored (but not the anchor point coordinates)
-ocv=0x0+2x2/custom=diamond.shape:2
-
The filter takes the following parameters:
-type:param1:param2:param3:param4.
-
-
type is the type of smooth filter to apply, and can be one of
-the following values: "blur", "blur_no_scale", "median", "gaussian",
-"bilateral". The default value is "gaussian".
-
-
param1, param2, param3, and param4 are
-parameters whose meanings depend on smooth type. param1 and
-param2 accept integer positive values or 0, param3 and
-param4 accept float values.
-
-
The default value for param1 is 3, the default value for the
-other parameters is 0.
-
-
These parameters correspond to the parameters assigned to the
-libopencv function cvSmooth.
-
It takes two inputs and one output, the first input is the "main"
-video on which the second input is overlayed.
-
-
It accepts the parameters: x:y[:options].
-
-
x is the x coordinate of the overlayed video on the main video,
-y is the y coordinate. x and y are expressions containing
-the following parameters:
-
-
-
‘main_w, main_h’
-
main input width and height
-
-
-
‘W, H’
-
same as main_w and main_h
-
-
-
‘overlay_w, overlay_h’
-
overlay input width and height
-
-
-
‘w, h’
-
same as overlay_w and overlay_h
-
-
-
-
options is an optional list of key=value pairs,
-separated by ":".
-
-
The description of the accepted options follows.
-
-
-
‘rgb’
-
If set to 1, force the filter to accept inputs in the RGB
-color space. Default value is 0.
-
-
-
-
Be aware that frames are taken from each input video in timestamp
-order, hence, if their initial timestamps differ, it is a a good idea
-to pass the two inputs through a setpts=PTS-STARTPTS filter to
-have them begin in the same zero timestamp, as it does the example for
-the movie filter.
-
-
Follow some examples:
-
# draw the overlay at 10 pixels from the bottom right
-# corner of the main video.
-overlay=main_w-overlay_w-10:main_h-overlay_h-10
-
-# insert a transparent PNG logo in the bottom left corner of the input
-movie=logo.png [logo];
-[in][logo] overlay=10:main_h-overlay_h-10 [out]
-
-# insert 2 different transparent PNG logos (second logo on bottom
-# right corner):
-movie=logo1.png [logo1];
-movie=logo2.png [logo2];
-[in][logo1] overlay=10:H-h-10 [in+logo1];
-[in+logo1][logo2] overlay=W-w-10:H-h-10 [out]
-
-# add a transparent color layer on top of the main video,
-# WxH specifies the size of the main input to the overlay filter
-color=red.3:WxH [over]; [in][over] overlay [out]
-
-
-
You can chain together more overlays but the efficiency of such
-approach is yet to be tested.
-
Add paddings to the input image, and places the original input at the
-given coordinates x, y.
-
-
It accepts the following parameters:
-width:height:x:y:color.
-
-
The parameters width, height, x, and y are
-expressions containing the following constants:
-
-
-
‘in_w, in_h’
-
the input video width and height
-
-
-
‘iw, ih’
-
same as in_w and in_h
-
-
-
‘out_w, out_h’
-
the output width and height, that is the size of the padded area as
-specified by the width and height expressions
-
-
-
‘ow, oh’
-
same as out_w and out_h
-
-
-
‘x, y’
-
x and y offsets as specified by the x and y
-expressions, or NAN if not yet specified
-
-
-
‘a’
-
same as iw / ih
-
-
-
‘sar’
-
input sample aspect ratio
-
-
-
‘dar’
-
input display aspect ratio, it is the same as (iw / ih) * sar
-
-
-
‘hsub, vsub’
-
horizontal and vertical chroma subsample values. For example for the
-pixel format "yuv422p" hsub is 2 and vsub is 1.
-
-
-
-
Follows the description of the accepted parameters.
-
-
-
‘width, height’
-
-
Specify the size of the output image with the paddings added. If the
-value for width or height is 0, the corresponding input size
-is used for the output.
-
-
The width expression can reference the value set by the
-height expression, and vice versa.
-
-
The default value of width and height is 0.
-
-
-
‘x, y’
-
-
Specify the offsets where to place the input image in the padded area
-with respect to the top/left border of the output image.
-
-
The x expression can reference the value set by the y
-expression, and vice versa.
-
-
The default value of x and y is 0.
-
-
-
‘color’
-
-
Specify the color of the padded area, it can be the name of a color
-(case insensitive match) or a 0xRRGGBB[AA] sequence.
-
-
The default value of color is "black".
-
-
-
-
-
Some examples follow:
-
-
# Add paddings with color "violet" to the input video. Output video
-# size is 640x480, the top-left corner of the input video is placed at
-# column 0, row 40.
-pad=640:480:0:40:violet
-
-# pad the input to get an output with dimensions increased bt 3/2,
-# and put the input video at the center of the padded area
-pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
-
-# pad the input to get a squared output with size equal to the maximum
-# value between the input width and height, and put the input video at
-# the center of the padded area
-pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
-
-# pad the input to get a final w/h ratio of 16:9
-pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
-
-# for anamorphic video, in order to set the output display aspect ratio,
-# it is necessary to use sar in the expression, according to the relation:
-# (ih * X / ih) * sar = output_dar
-# X = output_dar / sar
-pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2"
-
-# double output size and put the input video in the bottom-right
-# corner of the output padded area
-pad="2*iw:2*ih:ow-iw:oh-ih"
-
Scale the input video to width:height[:interl={1|-1}] and/or convert the image format.
-
-
The parameters width and height are expressions containing
-the following constants:
-
-
-
‘in_w, in_h’
-
the input width and height
-
-
-
‘iw, ih’
-
same as in_w and in_h
-
-
-
‘out_w, out_h’
-
the output (cropped) width and height
-
-
-
‘ow, oh’
-
same as out_w and out_h
-
-
-
‘a’
-
same as iw / ih
-
-
-
‘sar’
-
input sample aspect ratio
-
-
-
‘dar’
-
input display aspect ratio, it is the same as (iw / ih) * sar
-
-
-
‘hsub, vsub’
-
horizontal and vertical chroma subsample values. For example for the
-pixel format "yuv422p" hsub is 2 and vsub is 1.
-
-
-
-
If the input image format is different from the format requested by
-the next filter, the scale filter will convert the input to the
-requested format.
-
-
If the value for width or height is 0, the respective input
-size is used for the output.
-
-
If the value for width or height is -1, the scale filter will
-use, for the respective output size, a value that maintains the aspect
-ratio of the input image.
-
-
The default value of width and height is 0.
-
-
Valid values for the optional parameter interl are:
-
-
-
‘1’
-
force interlaced aware scaling
-
-
-
‘-1’
-
select interlaced aware scaling depending on whether the source frames
-are flagged as interlaced or not
-
-
-
-
Some examples follow:
-
# scale the input video to a size of 200x100.
-scale=200:100
-
-# scale the input to 2x
-scale=2*iw:2*ih
-# the above is the same as
-scale=2*in_w:2*in_h
-
-# scale the input to half size
-scale=iw/2:ih/2
-
-# increase the width, and set the height to the same size
-scale=3/2*iw:ow
-
-# seek for Greek harmony
-scale=iw:1/PHI*iw
-scale=ih*PHI:ih
-
-# increase the height, and set the width to 3/2 of the height
-scale=3/2*oh:3/5*ih
-
-# increase the size, but make the size a multiple of the chroma
-scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
-
-# increase the width to a maximum of 500 pixels, keep the same input aspect ratio
-scale='min(500\, iw*3/2):-1'
-
It accepts in input an expression, which is evaluated for each input
-frame. If the expression is evaluated to a non-zero value, the frame
-is selected and passed to the output, otherwise it is discarded.
-
-
The expression can contain the following constants:
-
-
-
‘n’
-
the sequential number of the filtered frame, starting from 0
-
-
-
‘selected_n’
-
the sequential number of the selected frame, starting from 0
-
-
-
‘prev_selected_n’
-
the sequential number of the last selected frame, NAN if undefined
-
-
-
‘TB’
-
timebase of the input timestamps
-
-
-
‘pts’
-
the PTS (Presentation TimeStamp) of the filtered video frame,
-expressed in TB units, NAN if undefined
-
-
-
‘t’
-
the PTS (Presentation TimeStamp) of the filtered video frame,
-expressed in seconds, NAN if undefined
-
-
-
‘prev_pts’
-
the PTS of the previously filtered video frame, NAN if undefined
-
-
-
‘prev_selected_pts’
-
the PTS of the last previously filtered video frame, NAN if undefined
-
-
-
‘prev_selected_t’
-
the PTS of the last previously selected video frame, NAN if undefined
-
-
-
‘start_pts’
-
the PTS of the first video frame in the video, NAN if undefined
-
-
-
‘start_t’
-
the time of the first video frame in the video, NAN if undefined
-
-
-
‘pict_type’
-
the type of the filtered frame, can assume one of the following
-values:
-
-
‘I’
-
‘P’
-
‘B’
-
‘S’
-
‘SI’
-
‘SP’
-
‘BI’
-
-
-
-
‘interlace_type’
-
the frame interlace type, can assume one of the following values:
-
-
‘PROGRESSIVE’
-
the frame is progressive (not interlaced)
-
-
‘TOPFIRST’
-
the frame is top-field-first
-
-
‘BOTTOMFIRST’
-
the frame is bottom-field-first
-
-
-
-
-
‘key’
-
1 if the filtered frame is a key-frame, 0 otherwise
-
-
-
‘pos’
-
the position in the file of the filtered frame, -1 if the information
-is not available (e.g. for synthetic video)
-
-
-
-
The default value of the select expression is "1".
-
-
Some examples follow:
-
-
# select all frames in input
-select
-
-# the above is the same as:
-select=1
-
-# skip all frames:
-select=0
-
-# select only I-frames
-select='eq(pict_type\,I)'
-
-# select one frame every 100
-select='not(mod(n\,100))'
-
-# select only frames contained in the 10-20 time interval
-select='gte(t\,10)*lte(t\,20)'
-
-# select only I frames contained in the 10-20 time interval
-select='gte(t\,10)*lte(t\,20)*eq(pict_type\,I)'
-
-# select frames with a minimum distance of 10 seconds
-select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
-
Set the Display Aspect Ratio for the filter output video.
-
-
This is done by changing the specified Sample (aka Pixel) Aspect
-Ratio, according to the following equation:
-DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR
-
-
Keep in mind that this filter does not modify the pixel dimensions of
-the video frame. Also the display aspect ratio set by this filter may
-be changed by later filters in the filterchain, e.g. in case of
-scaling or if another "setdar" or a "setsar" filter is applied.
-
-
The filter accepts a parameter string which represents the wanted
-display aspect ratio.
-The parameter can be a floating point number string, or an expression
-of the form num:den, where num and den are the
-numerator and denominator of the aspect ratio.
-If the parameter is not specified, it is assumed the value "0:1".
-
-
For example to change the display aspect ratio to 16:9, specify:
-
setdar=16:9
-# the above is equivalent to
-setdar=1.77777
-
Set the Sample (aka Pixel) Aspect Ratio for the filter output video.
-
-
Note that as a consequence of the application of this filter, the
-output display aspect ratio will change according to the following
-equation:
-DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR
-
-
Keep in mind that the sample aspect ratio set by this filter may be
-changed by later filters in the filterchain, e.g. if another "setsar"
-or a "setdar" filter is applied.
-
-
The filter accepts a parameter string which represents the wanted
-sample aspect ratio.
-The parameter can be a floating point number string, or an expression
-of the form num:den, where num and den are the
-numerator and denominator of the aspect ratio.
-If the parameter is not specified, it is assumed the value "0:1".
-
-
For example to change the sample aspect ratio to 10:11, specify:
-
Set the timebase to use for the output frames timestamps.
-It is mainly useful for testing timebase configuration.
-
-
It accepts in input an arithmetic expression representing a rational.
-The expression can contain the constants "AVTB" (the
-default timebase), and "intb" (the input timebase).
-
-
The default value for the input is "intb".
-
-
Follow some examples.
-
-
# set the timebase to 1/25
-settb=1/25
-
-# set the timebase to 1/10
-settb=0.1
-
-#set the timebase to 1001/1000
-settb=1+0.001
-
-#set the timebase to 2*intb
-settb=2*intb
-
-#set the default timebase value
-settb=AVTB
-
Show a line containing various information for each input video frame.
-The input video is not modified.
-
-
The shown line contains a sequence of key/value pairs of the form
-key:value.
-
-
A description of each shown parameter follows:
-
-
-
‘n’
-
sequential number of the input frame, starting from 0
-
-
-
‘pts’
-
Presentation TimeStamp of the input frame, expressed as a number of
-time base units. The time base unit depends on the filter input pad.
-
-
-
‘pts_time’
-
Presentation TimeStamp of the input frame, expressed as a number of
-seconds
-
-
-
‘pos’
-
position of the frame in the input stream, -1 if this information in
-unavailable and/or meaningless (for example in case of synthetic video)
-
-
-
‘fmt’
-
pixel format name
-
-
-
‘sar’
-
sample aspect ratio of the input frame, expressed in the form
-num/den
-
-
-
‘s’
-
size of the input frame, expressed in the form
-widthxheight
-
-
-
‘i’
-
interlaced mode ("P" for "progressive", "T" for top field first, "B"
-for bottom field first)
-
-
-
‘iskey’
-
1 if the frame is a key frame, 0 otherwise
-
-
-
‘type’
-
picture type of the input frame ("I" for an I-frame, "P" for a
-P-frame, "B" for a B-frame, "?" for unknown type).
-Check also the documentation of the AVPictureType enum and of
-the av_get_picture_type_char function defined in
-‘libavutil/avutil.h’.
-
-
-
‘checksum’
-
Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame
-
-
-
‘plane_checksum’
-
Adler-32 checksum (printed in hexadecimal) of each plane of the input frame,
-expressed in the form "[c0c1c2c3]"
-
Select the most representative frame in a given sequence of consecutive frames.
-
-
It accepts as argument the frames batch size to analyze (default N=100);
-in a set of N frames, the filter will pick one of them, and then handle
-the next batch of N frames until the end.
-
-
Since the filter keeps track of the whole frames sequence, a bigger N
-value will result in a higher memory usage, so a high value is not recommended.
-
-
The following example extract one picture each 50 frames:
-
thumbnail=50
-
-
-
Complete example of a thumbnail creation with ffmpeg:
-
It accepts the following parameters:
-luma_msize_x:luma_msize_y:luma_amount:chroma_msize_x:chroma_msize_y:chroma_amount
-
-
Negative values for the amount will blur the input video, while positive
-values will sharpen. All parameters are optional and default to the
-equivalent of the string ’5:5:1.0:5:5:0.0’.
-
-
-
‘luma_msize_x’
-
Set the luma matrix horizontal size. It can be an integer between 3
-and 13, default value is 5.
-
-
-
‘luma_msize_y’
-
Set the luma matrix vertical size. It can be an integer between 3
-and 13, default value is 5.
-
-
-
‘luma_amount’
-
Set the luma effect strength. It can be a float number between -2.0
-and 5.0, default value is 1.0.
-
-
-
‘chroma_msize_x’
-
Set the chroma matrix horizontal size. It can be an integer between 3
-and 13, default value is 5.
-
-
-
‘chroma_msize_y’
-
Set the chroma matrix vertical size. It can be an integer between 3
-and 13, default value is 5.
-
-
-
‘chroma_amount’
-
Set the chroma effect strength. It can be a float number between -2.0
-and 5.0, default value is 0.0.
-
-
-
-
-
# Strong luma sharpen effect parameters
-unsharp=7:7:2.5
-
-# Strong blur of both luma and chroma parameters
-unsharp=7:7:-2:7:7:-2
-
-# Use the default values with ffmpeg
-ffmpeg -i in.avi -vf "unsharp" out.mp4
-
Buffer video frames, and make them available to the filter chain.
-
-
This source is mainly intended for a programmatic use, in particular
-through the interface defined in ‘libavfilter/vsrc_buffer.h’.
-
-
It accepts the following parameters:
-width:height:pix_fmt_string:timebase_num:timebase_den:sample_aspect_ratio_num:sample_aspect_ratio.den:scale_params
-
-
All the parameters but scale_params need to be explicitly
-defined.
-
-
Follows the list of the accepted parameters.
-
-
-
‘width, height’
-
Specify the width and height of the buffered video frames.
-
-
-
‘pix_fmt_string’
-
A string representing the pixel format of the buffered video frames.
-It may be a number corresponding to a pixel format, or a pixel format
-name.
-
-
-
‘timebase_num, timebase_den’
-
Specify numerator and denomitor of the timebase assumed by the
-timestamps of the buffered frames.
-
Specify numerator and denominator of the sample aspect ratio assumed
-by the video frames.
-
-
-
‘scale_params’
-
Specify the optional parameters to be used for the scale filter which
-is automatically inserted when an input change is detected in the
-input size or format.
-
-
-
-
For example:
-
buffer=320:240:yuv410p:1:24:1:1
-
-
-
will instruct the source to accept video frames with size 320x240 and
-with format "yuv410p", assuming 1/24 as the timestamps timebase and
-square pixels (1:1 sample aspect ratio).
-Since the pixel format with name "yuv410p" corresponds to the number 6
-(check the enum PixelFormat definition in ‘libavutil/pixfmt.h’),
-this example corresponds to:
-
Create a pattern generated by an elementary cellular automaton.
-
-
The initial state of the cellular automaton can be defined through the
-‘filename’, and ‘pattern’ options. If such options are
-not specified an initial state is created randomly.
-
-
At each new frame a new row in the video is filled with the result of
-the cellular automaton next generation. The behavior when the whole
-frame is filled is defined by the ‘scroll’ option.
-
-
This source accepts a list of options in the form of
-key=value pairs separated by ":". A description of the
-accepted options follows.
-
-
-
‘filename, f’
-
Read the initial cellular automaton state, i.e. the starting row, from
-the specified file.
-In the file, each non-whitespace character is considered an alive
-cell, a newline will terminate the row, and further characters in the
-file will be ignored.
-
-
-
‘pattern, p’
-
Read the initial cellular automaton state, i.e. the starting row, from
-the specified string.
-
-
Each non-whitespace character in the string is considered an alive
-cell, a newline will terminate the row, and further characters in the
-string will be ignored.
-
-
-
‘rate, r’
-
Set the video rate, that is the number of frames generated per second.
-Default is 25.
-
-
-
‘random_fill_ratio, ratio’
-
Set the random fill ratio for the initial cellular automaton row. It
-is a floating point number value ranging from 0 to 1, defaults to
-1/PHI.
-
-
This option is ignored when a file or a pattern is specified.
-
-
-
‘random_seed, seed’
-
Set the seed for filling randomly the initial row, must be an integer
-included between 0 and UINT32_MAX. If not specified, or if explicitly
-set to -1, the filter will try to use a good random seed on a best
-effort basis.
-
-
-
‘rule’
-
Set the cellular automaton rule, it is a number ranging from 0 to 255.
-Default value is 110.
-
-
-
‘size, s’
-
Set the size of the output video.
-
-
If ‘filename’ or ‘pattern’ is specified, the size is set
-by default to the width of the specified initial state row, and the
-height is set to width * PHI.
-
-
If ‘size’ is set, it must contain the width of the specified
-pattern string, and the specified pattern will be centered in the
-larger row.
-
-
If a filename or a pattern string is not specified, the size value
-defaults to "320x518" (used for a randomly generated initial state).
-
-
-
‘scroll’
-
If set to 1, scroll the output upward when all the rows in the output
-have been already filled. If set to 0, the new generated row will be
-written over the top row just after the bottom row is filled.
-Defaults to 1.
-
-
-
‘start_full, full’
-
If set to 1, completely fill the output with generated rows before
-outputting the first frame.
-This is the default behavior, for disabling set the value to 0.
-
-
-
‘stitch’
-
If set to 1, stitch the left and right row edges together.
-This is the default behavior, for disabling set the value to 0.
-
It accepts the following parameters:
-color:frame_size:frame_rate
-
-
Follows the description of the accepted parameters.
-
-
-
‘color’
-
Specify the color of the source. It can be the name of a color (case
-insensitive match) or a 0xRRGGBB[AA] sequence, possibly followed by an
-alpha specifier. The default value is "black".
-
-
-
‘frame_size’
-
Specify the size of the sourced video, it may be a string of the form
-widthxheight, or the name of a size abbreviation. The
-default value is "320x240".
-
-
-
‘frame_rate’
-
Specify the frame rate of the sourced video, as the number of frames
-generated per second. It has to be a string in the format
-frame_rate_num/frame_rate_den, an integer number, a float
-number or a valid video frame rate abbreviation. The default value is
-"25".
-
-
-
-
-
For example the following graph description will generate a red source
-with an opacity of 0.2, with size "qcif" and a frame rate of 10
-frames per second, which will be overlayed over the source connected
-to the pad with identifier "in".
-
It accepts the syntax: movie_name[:options] where
-movie_name is the name of the resource to read (not necessarily
-a file but also a device or a stream accessed through some protocol),
-and options is an optional sequence of key=value
-pairs, separated by ":".
-
-
The description of the accepted options follows.
-
-
-
‘format_name, f’
-
Specifies the format assumed for the movie to read, and can be either
-the name of a container or an input device. If not specified the
-format is guessed from movie_name or by probing.
-
-
-
‘seek_point, sp’
-
Specifies the seek point in seconds, the frames will be output
-starting from this seek point, the parameter is evaluated with
-av_strtod so the numerical value may be suffixed by an IS
-postfix. Default value is "0".
-
-
-
‘stream_index, si’
-
Specifies the index of the video stream to read. If the value is -1,
-the best suited video stream will be automatically selected. Default
-value is "-1".
-
-
-
-
-
This filter allows to overlay a second video on top of main input of
-a filtergraph as shown in this graph:
-
# skip 3.2 seconds from the start of the avi file in.avi, and overlay it
-# on top of the input labelled as "in".
-movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [movie];
-[in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
-
-# read from a video4linux2 device, and overlay it on top of the input
-# labelled as "in"
-movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [movie];
-[in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
-
-
The size of the generated video is fixed, and is 256x256.
-This source is useful in particular for testing encoding features.
-
-
This source accepts an optional sequence of key=value pairs,
-separated by ":". The description of the accepted options follows.
-
-
-
‘rate, r’
-
Specify the frame rate of the sourced video, as the number of frames
-generated per second. It has to be a string in the format
-frame_rate_num/frame_rate_den, an integer number, a float
-number or a valid video frame rate abbreviation. The default value is
-"25".
-
-
-
‘duration, d’
-
Set the video duration of the sourced video. The accepted syntax is:
-
[-]HH[:MM[:SS[.m...]]]
-[-]S+[.m...]
-
-
See also the function av_parse_time().
-
-
If not specified, or the expressed duration is negative, the video is
-supposed to be generated forever.
-
-
-
‘test, t’
-
-
Set the number or the name of the test to perform. Supported tests are:
-
-
‘dc_luma’
-
‘dc_chroma’
-
‘freq_luma’
-
‘freq_chroma’
-
‘amp_luma’
-
‘amp_chroma’
-
‘cbp’
-
‘mv’
-
‘ring1’
-
‘ring2’
-
‘all’
-
-
-
Default value is "all", which will cycle through the list of all tests.
-
size is the size of the video to generate, may be a string of the
-form widthxheight or a frame size abbreviation.
-rate is the rate of the video to generate, may be a string of
-the form num/den or a frame rate abbreviation.
-src_name is the name to the frei0r source to load. For more
-information regarding frei0r and how to set the parameters read the
-section frei0r in the description of the video filters.
-
-
Some examples follow:
-
# generate a frei0r partik0l source with size 200x200 and frame rate 10
-# which is overlayed on the overlay filter main input
-frei0r_src=200x200:10:partik0l=1234 [overlay]; [in][overlay] overlay
-
This source is based on a generalization of John Conway’s life game.
-
-
The sourced input represents a life grid, each pixel represents a cell
-which can be in one of two possible states, alive or dead. Every cell
-interacts with its eight neighbours, which are the cells that are
-horizontally, vertically, or diagonally adjacent.
-
-
At each interaction the grid evolves according to the adopted rule,
-which specifies the number of neighbor alive cells which will make a
-cell stay alive or born. The ‘rule’ option allows to specify
-the rule to adopt.
-
-
This source accepts a list of options in the form of
-key=value pairs separated by ":". A description of the
-accepted options follows.
-
-
-
‘filename, f’
-
Set the file from which to read the initial grid state. In the file,
-each non-whitespace character is considered an alive cell, and newline
-is used to delimit the end of each row.
-
-
If this option is not specified, the initial grid is generated
-randomly.
-
-
-
‘rate, r’
-
Set the video rate, that is the number of frames generated per second.
-Default is 25.
-
-
-
‘random_fill_ratio, ratio’
-
Set the random fill ratio for the initial random grid. It is a
-floating point number value ranging from 0 to 1, defaults to 1/PHI.
-It is ignored when a file is specified.
-
-
-
‘random_seed, seed’
-
Set the seed for filling the initial random grid, must be an integer
-included between 0 and UINT32_MAX. If not specified, or if explicitly
-set to -1, the filter will try to use a good random seed on a best
-effort basis.
-
-
-
‘rule’
-
Set the life rule.
-
-
A rule can be specified with a code of the kind "SNS/BNB",
-where NS and NB are sequences of numbers in the range 0-8,
-NS specifies the number of alive neighbor cells which make a
-live cell stay alive, and NB the number of alive neighbor cells
-which make a dead cell to become alive (i.e. to "born").
-"s" and "b" can be used in place of "S" and "B", respectively.
-
-
Alternatively a rule can be specified by an 18-bits integer. The 9
-high order bits are used to encode the next cell state if it is alive
-for each number of neighbor alive cells, the low order bits specify
-the rule for "borning" new cells. Higher order bits encode for an
-higher number of neighbor cells.
-For example the number 6153 = (12<<9)+9 specifies a stay alive
-rule of 12 and a born rule of 9, which corresponds to "S23/B03".
-
-
Default value is "S23/B3", which is the original Conway’s game of life
-rule, and will keep a cell alive if it has 2 or 3 neighbor alive
-cells, and will born a new cell if there are three alive cells around
-a dead cell.
-
-
-
‘size, s’
-
Set the size of the output video.
-
-
If ‘filename’ is specified, the size is set by default to the
-same size of the input file. If ‘size’ is set, it must contain
-the size specified in the input file, and the initial grid defined in
-that file is centered in the larger resulting area.
-
-
If a filename is not specified, the size value defaults to "320x240"
-(used for a randomly generated initial grid).
-
-
-
‘stitch’
-
If set to 1, stitch the left and right grid edges together, and the
-top and bottom edges also. Defaults to 1.
-
-
-
‘mold’
-
Set cell mold speed. If set, a dead cell will go from ‘death_color’ to
-‘mold_color’ with a step of ‘mold’. ‘mold’ can have a
-value from 0 to 255.
-
-
-
‘life_color’
-
Set the color of living (or new born) cells.
-
-
-
‘death_color’
-
Set the color of dead cells. If ‘mold’ is set, this is the first color
-used to represent a dead cell.
-
-
-
‘mold_color’
-
Set mold color, for definitely dead and moldy cells.
-
The nullsrc source returns unprocessed video frames. It is
-mainly useful to be employed in analysis / debugging tools, or as the
-source for filters which ignore the input data.
-
-
The rgbtestsrc source generates an RGB test pattern useful for
-detecting RGB vs BGR issues. You should see a red, green and blue
-stripe from top to bottom.
-
-
The testsrc source generates a test video pattern, showing a
-color pattern, a scrolling gradient and a timestamp. This is mainly
-intended for testing purposes.
-
-
These sources accept an optional sequence of key=value pairs,
-separated by ":". The description of the accepted options follows.
-
-
-
‘size, s’
-
Specify the size of the sourced video, it may be a string of the form
-widthxheight, or the name of a size abbreviation. The
-default value is "320x240".
-
-
-
‘rate, r’
-
Specify the frame rate of the sourced video, as the number of frames
-generated per second. It has to be a string in the format
-frame_rate_num/frame_rate_den, an integer number, a float
-number or a valid video frame rate abbreviation. The default value is
-"25".
-
-
-
‘sar’
-
Set the sample aspect ratio of the sourced video.
-
-
-
‘duration, d’
-
Set the video duration of the sourced video. The accepted syntax is:
-
[-]HH[:MM[:SS[.m...]]]
-[-]S+[.m...]
-
-
See also the function av_parse_time().
-
-
If not specified, or the expressed duration is negative, the video is
-supposed to be generated forever.
-
-
-
‘decimals, n’
-
Set the number of decimals to show in the timestamp, only used in the
-testsrc source.
-
-
The displayed timestamp value will correspond to the original
-timestamp value multiplied by the power of 10 of the specified
-value. Default value is 0.
-
-
-
-
For example the following:
-
testsrc=duration=5.3:size=qcif:rate=10
-
-
-
will generate a video with a duration of 5.3 seconds, with size
-176x144 and a frame rate of 10 frames per second.
-
-
If the input content is to be ignored, nullsrc can be used. The
-following command generates noise in the luminance plane by employing
-the mp=geq filter:
-
Buffer video frames, and make them available to the end of the filter
-graph.
+
The FFmpeg developers.
-
This sink is mainly intended for a programmatic use, in particular
-through the interface defined in ‘libavfilter/buffersink.h’.
+
For details about the authorship, see the Git history of the project
+(git://source.ffmpeg.org/ffmpeg), e.g. by typing the command
+git log in the FFmpeg source directory, or browsing the
+online repository at http://source.ffmpeg.org.
-
It does not require a string parameter in input, but you need to
-specify a pointer to a list of supported pixel formats terminated by
--1 in the opaque parameter provided to avfilter_init_filter
-when initializing this sink.
+
Maintainers for the specific components are listed in the file
+‘MAINTAINERS’ in the source code tree.
The libavformat library provides a generic framework for multiplexing
+and demultiplexing (muxing and demuxing) audio, video and subtitle
+streams. It encompasses multiple muxers and demuxers for multimedia
+container formats.
+
+
It also supports several input and output protocols to access a media
+resource.
+
For details about the authorship, see the Git history of the project
+(git://source.ffmpeg.org/ffmpeg), e.g. by typing the command
+git log in the FFmpeg source directory, or browsing the
+online repository at http://source.ffmpeg.org.
+
+
Maintainers for the specific components are listed in the file
+‘MAINTAINERS’ in the source code tree.
+
The libavutil library is a utility library to aid portable
+multimedia programming. It contains safe portable string functions,
+random number generators, data structures, additional mathematics
+functions, cryptography and multimedia related functionality (like
+enumerations for pixel and sample formats).
+
For details about the authorship, see the Git history of the project
+(git://source.ffmpeg.org/ffmpeg), e.g. by typing the command
+git log in the FFmpeg source directory, or browsing the
+online repository at http://source.ffmpeg.org.
+
+
Maintainers for the specific components are listed in the file
+‘MAINTAINERS’ in the source code tree.
+
The libswresample library performs highly optimized audio resampling,
+rematrixing and sample format conversion operations.
+
+
Specifically, this library performs the following conversions:
+
+
+
+Resampling: is the process of changing the audio rate, for
+example from a high sample rate of 44100Hz to 8000Hz. Audio
+conversion from high to low sample rate is a lossy process. Several
+resampling options and algorithms are available.
+
+
+Format conversion: is the process of converting the type of
+samples, for example from 16-bit signed samples to unsigned 8-bit or
+float samples. It also handles packing conversion, when passing from
+packed layout (all samples belonging to distinct channels interleaved
+in the same buffer), to planar layout (all samples belonging to the
+same channel stored in a dedicated buffer or "plane").
+
+
+Rematrixing: is the process of changing the channel layout, for
+example from stereo to mono. When the input channels cannot be mapped
+to the output streams, the process is lossy, since it involves
+different gain factors and mixing.
+
+
+
Various other audio conversions (e.g. stretching and padding) are
+enabled through dedicated options.
+
For details about the authorship, see the Git history of the project
+(git://source.ffmpeg.org/ffmpeg), e.g. by typing the command
+git log in the FFmpeg source directory, or browsing the
+online repository at http://source.ffmpeg.org.
+
+
Maintainers for the specific components are listed in the file
+‘MAINTAINERS’ in the source code tree.
+
The libswscale library performs highly optimized image scaling and
+colorspace and pixel format conversion operations.
+
+
Specifically, this library performs the following conversions:
+
+
+
+Rescaling: is the process of changing the video size. Several
+rescaling options and algorithms are available. This is usually a
+lossy process.
+
+
+Pixel format conversion: is the process of converting the image
+format and colorspace of the image, for example from planar YUV420P to
+RGB24 packed. It also handles packing conversion, that is converts
+from packed layout (all pixels belonging to distinct planes
+interleaved in the same buffer), to planar layout (all samples
+belonging to the same plane stored in a dedicated buffer or "plane").
+
+
This is usually a lossy process in case the source and destination
+colorspaces differ.
+
For details about the authorship, see the Git history of the project
+(git://source.ffmpeg.org/ffmpeg), e.g. by typing the command
+git log in the FFmpeg source directory, or browsing the
+online repository at http://source.ffmpeg.org.
+
+
Maintainers for the specific components are listed in the file
+‘MAINTAINERS’ in the source code tree.
+
NUT is a low overhead generic container format. It stores audio, video,
+subtitle and user-defined streams in a simple, yet efficient, way.
+
+
It was created by a group of FFmpeg and MPlayer developers in 2003
+and was finalized in 2008.
+
+
The official nut specification is at svn://svn.mplayerhq.hu/nut
+In case of any differences between this text and the official specification,
+the official specification shall prevail.
+
Since many exotic planar YUVA pixel formats are not considered by
+the AVI/QuickTime FourCC lists, the following scheme is adopted for
+representing them.
+
+
The first two bytes can contain the values:
+Y1 = only Y
+Y2 = Y+A
+Y3 = YUV
+Y4 = YUVA
+
+
The third byte represents the width and height chroma subsampling
+values for the UV planes, that is the amount to shift the luma
+width/height right to find the chroma width/height.
+
+
The fourth byte is the number of bits used (8, 16, ...).
+
+
If the order of bytes is inverted, that means that each component has
+to be read big-endian.
+
GNU Make is required to build FFmpeg, so you have to invoke (‘gmake’),
+
GNU Make is required to build FFmpeg, so you have to invoke (gmake),
standard Solaris Make will not work. When building with a non-c99 front-end
(gcc, generic suncc) add either --extra-libs=/usr/lib/values-xpg6.o
or --extra-libs=/usr/lib/64/values-xpg6.o to the configure options
@@ -190,31 +130,16 @@ or MacPorts can easily provide it.
FFmpeg can be built to run natively on Windows using the MinGW tools. Install
-the latest versions of MSYS and MinGW from http://www.mingw.org/.
-You can find detailed installation instructions in the download
-section and the FAQ.
-
-
FFmpeg does not build out-of-the-box with the packages the automated MinGW
-installer provides. It also requires coreutils to be installed and many other
-packages updated to the latest version. The minimum version for some packages
-are listed below:
-
FFmpeg can be built to run natively on Windows using the MinGW or MinGW-w64
+toolchains. Install the latest versions of MSYS and MinGW or MinGW-w64 from
+http://www.mingw.org/ or http://mingw-w64.sourceforge.net/.
+You can find detailed installation instructions in the download section and
+the FAQ.
By using ./configure --enable-shared when configuring FFmpeg,
you can build the FFmpeg libraries (e.g. libavutil, libavcodec,
@@ -237,146 +159,105 @@ libavformat) as DLLs.
As stated in the FAQ, FFmpeg will not compile under MSVC++. However, if you
-want to use the libav* libraries in your own applications, you can still
-compile those applications using MSVC++. But the libav* libraries you link
-to must be built with MinGW. However, you will not be able to debug
-inside the libav* libraries, since MSVC++ does not recognize the debug
-symbols generated by GCC.
-We strongly recommend you to move over from MSVC++ to MinGW tools.
+
FFmpeg can be built with MSVC or ICL using a C99-to-C89 conversion utility and
+wrapper. For ICL, only the wrapper is used, since ICL supports C99.
-
This description of how to use the FFmpeg libraries with MSVC++ is based on
-Microsoft Visual C++ 2005 Express Edition. If you have a different version,
-you might have to modify the procedures slightly.
+
Assuming you have just built and installed FFmpeg in ‘/usr/local’.
+
To set up a proper environment in MSYS, you need to run msys.bat from
+the Visual Studio or Intel Compiler command prompt.
-
-
Create a new console application ("File / New / Project") and then
-select "Win32 Console Application". On the appropriate page of the
-Application Wizard, uncheck the "Precompiled headers" option.
-
-
Write the source code for your application, or, for testing, just
-copy the code from an existing sample application into the source file
-that MSVC++ has already created for you. For example, you can copy
-‘libavformat/output-example.c’ from the FFmpeg distribution.
-
-
Open the "Project / Properties" dialog box. In the "Configuration"
-combo box, select "All Configurations" so that the changes you make will
-affect both debug and release builds. In the tree view on the left hand
-side, select "C/C++ / General", then edit the "Additional Include
-Directories" setting to contain the path where the FFmpeg includes were
-installed (i.e. ‘c:\msys\1.0\local\include’).
-Do not add MinGW’s include directory here, or the include files will
-conflict with MSVC’s.
-
-
Still in the "Project / Properties" dialog box, select
-"Linker / General" from the tree view and edit the
-"Additional Library Directories" setting to contain the ‘lib’
-directory where FFmpeg was installed (i.e. ‘c:\msys\1.0\local\lib’),
-the directory where MinGW libs are installed (i.e. ‘c:\mingw\lib’),
-and the directory where MinGW’s GCC libs are installed
-(i.e. ‘C:\mingw\lib\gcc\mingw32\4.2.1-sjlj’). Then select
-"Linker / Input" from the tree view, and add the files ‘libavformat.a’,
-‘libavcodec.a’, ‘libavutil.a’, ‘libmingwex.a’,
-‘libgcc.a’, and any other libraries you used (i.e. ‘libz.a’)
-to the end of "Additional Dependencies".
-
-
Now, select "C/C++ / Code Generation" from the tree view. Select
-"Debug" in the "Configuration" combo box. Make sure that "Runtime
-Library" is set to "Multi-threaded Debug DLL". Then, select "Release" in
-the "Configuration" combo box and make sure that "Runtime Library" is
-set to "Multi-threaded DLL".
-
-
Click "OK" to close the "Project / Properties" dialog box.
-
-
MSVC++ lacks some C99 header files that are fundamental for FFmpeg.
-Get msinttypes from http://code.google.com/p/msinttypes/downloads/list
-and install it in MSVC++’s include directory
-(i.e. ‘C:\Program Files\Microsoft Visual Studio 8\VC\include’).
-
-
MSVC++ also does not understand the inline keyword used by
-FFmpeg, so you must add this line before #includeing libav*:
-
#define inline _inline
-
-
-
Build your application, everything should work.
-
-
This is how to create DLL and LIB files that are compatible with MSVC++:
+
Place makedef, c99wrap.exe, c99conv.exe, and yasm.exe
+somewhere in your PATH.
-
-
Add a call to ‘vcvars32.bat’ (which sets up the environment
-variables for the Visual C++ tools) as the first line of ‘msys.bat’.
-The standard location for ‘vcvars32.bat’ is
-‘C:\Program Files\Microsoft Visual Studio 8\VC\bin\vcvars32.bat’,
-and the standard location for ‘msys.bat’ is ‘C:\msys\1.0\msys.bat’.
-If this corresponds to your setup, add the following line as the first line
-of ‘msys.bat’:
-
-
call "C:\Program Files\Microsoft Visual Studio 8\VC\bin\vcvars32.bat"
-
-
-
Alternatively, you may start the ‘Visual Studio 2005 Command Prompt’,
-and run ‘c:\msys\1.0\msys.bat’ from there.
+
Next, make sure inttypes.h and any other headers and libs you want to use
+are located in a spot that the compiler can see. Do so by modifying the LIB
+and INCLUDE environment variables to include the Windows paths to
+these directories. Alternatively, you can try and use the
+--extra-cflags/--extra-ldflags configure options.
-
Within the MSYS shell, run lib.exe. If you get a help message
-from ‘Microsoft (R) Library Manager’, this means your environment
-variables are set up correctly, the ‘Microsoft (R) Library Manager’
-is on the path and will be used by FFmpeg to create
-MSVC++-compatible import libraries.
+
Finally, run:
+
+
For MSVC:
+./configure --toolchain=msvc
-
Build FFmpeg with
+For ICL:
+./configure --toolchain=icl
-
./configure --enable-shared
make
make install
-
Your install path (‘/usr/local/’ by default) should now have the
-necessary DLL and LIB files under the ‘bin’ directory.
+
If you wish to compile shared libraries, add --enable-shared to your
+configure options. Note that due to the way MSVC and ICL handle DLL imports and
+exports, you cannot compile static and shared libraries at the same time, and
+enabling shared libraries will automatically disable the static ones.
+
Notes:
+
+
+
It is possible that coreutils’ link.exe conflicts with MSVC’s linker.
+You can find out by running which link to see which link.exe you
+are using. If it is located at /bin/link.exe, then you have the wrong one
+in your PATH. Either move or remove that copy, or make sure MSVC’s
+link.exe takes precedence in your PATH over coreutils’.
+
+
If you wish to build with zlib support, you will have to grab a compatible
+zlib binary from somewhere, with an MSVC import lib, or if you wish to link
+statically, you can follow the instructions below to build a compatible
+zlib.lib with MSVC. Regardless of which method you use, you must still
+follow step 3, or compilation will fail.
+
+
FFmpeg has been tested with the following on i686 and x86_64:
+
+
Visual Studio 2010 Pro and Express
+
Visual Studio 2012 Pro and Express
+
Intel Composer XE 2013
+
+
Anything else is not officially supported.
-
To use those files with MSVC++, do the same as you would do with
-the static libraries, as described above. But in Step 4,
-you should only need to add the directory where the LIB files are installed
-(i.e. ‘c:\msys\usr\local\bin’). This is not a typo, the LIB files are
-installed in the ‘bin’ directory. And instead of adding the static
-libraries (‘libxxx.a’ files) you should add the MSVC import libraries
-(‘avcodec.lib’, ‘avformat.lib’, and
-‘avutil.lib’). Note that you should not use the GCC import
-libraries (‘libxxx.dll.a’ files), as these will give you undefined
-reference errors. There should be no need for ‘libmingwex.a’,
-‘libgcc.a’, and ‘wsock32.lib’, nor any other external library
-statically linked into the DLLs.
+
If you plan to link with MSVC-built static libraries, you will need
+to make sure you have Runtime Library set to
+Multi-threaded (/MT) in your project’s settings.
-
FFmpeg headers do not declare global data for Windows DLLs through the usual
-dllexport/dllimport interface. Such data will be exported properly while
-building, but to use them in your MSVC++ code you will have to edit the
-appropriate headers and mark the data as dllimport. For example, in
-libavutil/pixdesc.h you should have:
-
You will need to define inline to something MSVC understands:
+
#define inline __inline
-
Note that using import libraries created by dlltool requires
-the linker optimization option to be set to
-"References: Keep Unreferenced Data (/OPT:NOREF)", otherwise
-the resulting binaries will fail during runtime. This isn’t
-required when using import libraries generated by lib.exe.
+
Also note, that as stated in Microsoft Visual C++, you will need
+an MSVC-compatible inttypes.h.
+
+
If you plan on using import libraries created by dlltool, you must
+set References to No (/OPT:NOREF) under the linker optimization
+settings, otherwise the resulting binaries will fail during runtime.
+This is not required when using import libraries generated by lib.exe.
This issue is reported upstream at
http://sourceware.org/bugzilla/show_bug.cgi?id=12633.
@@ -384,26 +265,23 @@ This issue is reported upstream at
(which is enabled by default in Release mode), follow these steps:
-
Open ‘Visual Studio 2005 Command Prompt’.
+
Open the Visual Studio Command Prompt.
Alternatively, in a normal command line prompt, call ‘vcvars32.bat’
which sets up the environment variables for the Visual C++ tools
-(the standard location for this file is
-‘C:\Program Files\Microsoft Visual Studio 8\VC\bin\vcvars32.bat’).
+(the standard location for this file is something like
+‘C:\Program Files (x86_\Microsoft Visual Studio 10.0\VC\bin\vcvars32.bat’).
Enter the ‘bin’ directory where the created LIB and DLL files
are stored.
-
The native Plan 9 compiler
+does not implement all the C99 features needed by FFmpeg so the gcc
+port must be used. Furthermore, a few items missing from the C
+library and shell environment need to be fixed.
-
-
-
+
+
GNU awk, grep, make, and sed
+
+
Working packages of these tools can be found at
+ports2plan9.
+They can be installed with 9front’spkg
+utility by setting pkgpath to
+http://ports2plan9.googlecode.com/files/.
+
+
Missing/broken head and printf commands
+
+
Replacements adequate for building FFmpeg can be found in the
+compat/plan9 directory. Place these somewhere they will be
+found by the shell. These are not full implementations of the
+commands and are not suitable for general use.
+
Some functions in the C library are missing or incomplete. The
+gcc-apelibs-1207 package from
+ports2plan9
+includes an updated C library, but installing the full package gives
+unusable executables. Instead, keep the files from gccbin.tgz
+under /386/lib/gnu. From the libc.a archive in the
+gcc-apelibs-1207 package, extract the following object files and
+turn them into a library:
+
+
+
strerror.o
+
strtoll.o
+
snprintf.o
+
vsnprintf.o
+
vfprintf.o
+
_IO_getc.o
+
_IO_putc.o
+
+
+
Use the --extra-libs option of configure to inform the
+build system of this library.
+
+
FPU exceptions enabled by default
+
+
Unlike most other systems, Plan 9 enables FPU exceptions by default.
+These must be disabled before calling any FFmpeg functions. While the
+included tools will do this automatically, other users of the
+libraries must do it themselves.
+