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Simple frame skip support

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This commit is contained in:
Glenn Maynard
2003-08-29 06:10:03 +00:00
parent 5fdf62e355
commit 18eb78de77
1 changed files with 72 additions and 26 deletions
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stepmania/src/arch/MovieTexture/MovieTexture_AVCodec.cpp
+72 -26
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@@ -310,6 +310,9 @@ void MovieTexture_AVCodec::DecoderThread()
bool GetNextTimestamp = true;
float CurrentTimestamp = 0, LastGoodTimestamp = 0, Last_IP_Timestamp=0;
bool FrameSkipMode = false;
unsigned Frame = 0;
CHECKPOINT;
while( m_State != DECODER_QUIT )
{
@@ -384,15 +387,13 @@ void MovieTexture_AVCodec::DecoderThread()
if (!got_frame)
continue;
++Frame;
/* We got a frame. Convert it. */
avcodec::AVPicture pict;
pict.data[0] = (unsigned char *)m_img->pixels;
pict.linesize[0] = m_img->pitch;
img_convert(&pict, AVPixelFormats[m_AVTexfmt].pf,
(avcodec::AVPicture *) &frame, m_stream->codec.pix_fmt,
m_stream->codec.width, m_stream->codec.height);
if ( m_stream->codec.has_b_frames &&
frame.pict_type != FF_B_TYPE )
swap( CurrentTimestamp, Last_IP_Timestamp );
@@ -410,33 +411,78 @@ void MovieTexture_AVCodec::DecoderThread()
CurrentTimestamp += frame.repeat_pict * (frame_delay * 0.5);
}
{
const float Offset = CurrentTimestamp - m_Timer;
/* If we're ahead, we're decoding too fast; delay. */
if( Offset > 0 )
SDL_Delay( int(1000*(CurrentTimestamp - m_Timer)) );
/* XXX: If we're behind, Offset will be negative and we
* simply won't delay, so the video will play fast until
* it catches up. However, if we're too far behind, we
* can take some steps to catch up. 1: We can stop updating
* the texture; 2: we can play with hurry_up. */
}
m_Position = CurrentTimestamp;
/* Signal the main thread to update the image on the next Update. */
m_ImageWaiting=true;
const float Offset = CurrentTimestamp - m_Timer;
bool SkipThisTextureUpdate = false;
/* If we're ahead, we're decoding too fast; delay. */
if( Offset > 0 )
{
SDL_Delay( int(1000*(CurrentTimestamp - m_Timer)) );
if( FrameSkipMode )
{
/* We're caught up; stop skipping frames. */
LOG->Trace( "stopped skipping frames" );
FrameSkipMode = false;
}
} else {
/* We're behind by -Offset seconds.
*
* If we're just slightly behind, don't worry about it; we'll simply
* not sleep, so we'll move as fast as we can to catch up.
*
* If we're far behind, we're short on CPU and we need to do something
* about it. We have at least two options:
*
* 1: We can skip texture updates. This is a big bottleneck on many
* systems.
*
* 2: If that's not enough, we can play with hurry_up.
*
* If we hit a threshold, start skipping frames via #1. If we do that,
* don't stop once we hit the threshold; keep doing it until we're fully
* caught up.
*
* I'm not sure when we should do #2. Also, we should try to notice if
* we simply don't have enough CPU for the video; it's better to just
* stay in frame skip mode than to enter and exit it constantly, but we
* don't want to do that due to a single timing glitch.
*/
const float FrameSkipThreshold = 0.5f;
if( -Offset >= FrameSkipThreshold && !FrameSkipMode )
{
LOG->Trace( "Entering frame skip mode" );
FrameSkipMode = true;
}
}
if( FrameSkipMode )
if( Frame % 2 )
SkipThisTextureUpdate = true;
if( m_State == PLAYING_ONE )
SDL_SemPost( m_OneFrameDecoded );
SkipThisTextureUpdate = false;
CHECKPOINT;
SDL_SemWait( m_BufferFinished );
CHECKPOINT;
/* If the frame wasn't used, then we must be shutting down. */
ASSERT( !m_ImageWaiting || m_State == DECODER_QUIT );
if( !SkipThisTextureUpdate )
{
img_convert(&pict, AVPixelFormats[m_AVTexfmt].pf,
(avcodec::AVPicture *) &frame, m_stream->codec.pix_fmt,
m_stream->codec.width, m_stream->codec.height);
/* Signal the main thread to update the image on the next Update. */
m_ImageWaiting=true;
if( m_State == PLAYING_ONE )
SDL_SemPost( m_OneFrameDecoded );
CHECKPOINT;
SDL_SemWait( m_BufferFinished );
CHECKPOINT;
/* If the frame wasn't used, then we must be shutting down. */
ASSERT( !m_ImageWaiting || m_State == DECODER_QUIT );
}
GetNextTimestamp = true;
}