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RageSoundReader::Read() returns sound data which may be at a

Browse Source 
different rate than the source it's reading from; one second
of returned data may correspond to two seconds in the source
material.

GetStreamToSourceRatio returns the ratio of returned data in
the next Read() call to source data.  This is propagated
upwards in the filter tree, so rate changes by a speed changer
in the middle of the tree will be reflected in the final
GetStreamToSourceRatio().

This means that whenever the ratio changes, Read() stops
returning data; it returns whatever it has, so the caller
has an opportunity to call GetStreamToSourceRatio again
and notice the change.

These semantics can be annoying to implement in some
cases, where only the processing of Read() may notice
a ratio change.  Read() may want to return 0, to say
"something changed, call GetStreamToSourceRatio again",
but 0 means EOF.

Add RageSoundReader::END_OF_FILE.  0 is now no
longer a special case; it means "there's more data, I
just didn't return any this time".  This is functionally
equivalent to errno EINTR.
This commit is contained in:
Glenn Maynard
2006-12-10 07:08:17 +00:00
parent 2f1782d892
commit 0b529a4960
11 changed files with 91 additions and 46 deletions
Download Patch File Download Diff File Expand all files Collapse all files
stepmania/src/RageSoundReader_SpeedChange.cpp
+30 -23
View File
@@ -85,7 +85,7 @@ static int FindClosestMatch( const int16_t *pBuffer, int iBufferSize, const int1
return iBestOffset;
}
void RageSoundReader_SpeedChange::FillData( int iMaxFrames )
int RageSoundReader_SpeedChange::FillData( int iMaxFrames )
{
/* XXX: If the rate or source frame offset changes in the source, we should stop
* at that point, so the changes propagate upward. That's tricky, since we want
@@ -97,13 +97,16 @@ void RageSoundReader_SpeedChange::FillData( int iMaxFrames )
int iFramesToRead = iMaxFrames - m_iDataBufferAvailFrames;
int iBytesToRead = iFramesToRead * m_Channels.size() * sizeof(int16_t);
if( iBytesToRead <= 0 )
return;
return m_iDataBufferAvailFrames;
int16_t *pTempBuffer = (int16_t *) alloca( iBytesToRead );
int iGotFrames = m_pSource->Read( (char *) pTempBuffer, iFramesToRead );
// if( iGotFrames == -1 ) XXX
if( !iGotFrames )
return;
if( iGotFrames < 0 )
{
if( iGotFrames == END_OF_FILE && m_iDataBufferAvailFrames )
return m_iDataBufferAvailFrames;
return iGotFrames;
}
for( size_t i = 0; i < m_Channels.size(); ++i )
{
@@ -124,6 +127,7 @@ void RageSoundReader_SpeedChange::FillData( int iMaxFrames )
m_iDataBufferAvailFrames += iGotFrames;
}
return m_iDataBufferAvailFrames;
}
void RageSoundReader_SpeedChange::EraseData( int iFramesToDelete )
@@ -145,15 +149,10 @@ void RageSoundReader_SpeedChange::EraseData( int iFramesToDelete )
}
}
bool RageSoundReader_SpeedChange::Step()
int RageSoundReader_SpeedChange::Step()
{
if( m_iDataBufferAvailFrames == 0 )
{
FillData( GetWindowSizeFrames() );
if( m_iDataBufferAvailFrames == 0 )
return false;
return true;
}
return FillData( GetWindowSizeFrames() );
/* If m_iPos is non-zero, we just finished playing a previous block, so advance forward. */
if( m_iPos )
@@ -186,15 +185,21 @@ bool RageSoundReader_SpeedChange::Step()
EraseData( iToDelete );
/* Fill as much data as we might need to do the search and use the result. */
int iMaxPositionNeeded = m_iUncorrelatedPos + GetToleranceFrames() + GetWindowSizeFrames();
for( size_t i = 0; i < m_Channels.size(); ++i )
iMaxPositionNeeded = max( iMaxPositionNeeded, m_Channels[i].m_iCorrelatedPos + GetWindowSizeFrames() );
FillData( iMaxPositionNeeded );
if( iMaxPositionNeeded > m_iDataBufferAvailFrames )
{
/* We're at EOF. Flush the remaining data, if any. */
m_iUncorrelatedPos = m_Channels[0].m_iCorrelatedPos;
return true;
int iMaxPositionNeeded = m_iUncorrelatedPos + GetToleranceFrames() + GetWindowSizeFrames();
for( size_t i = 0; i < m_Channels.size(); ++i )
iMaxPositionNeeded = max( iMaxPositionNeeded, m_Channels[i].m_iCorrelatedPos + GetWindowSizeFrames() );
int iGot = FillData( iMaxPositionNeeded );
if( iGot < 0 )
return iGot;
if( iMaxPositionNeeded > m_iDataBufferAvailFrames )
{
/* We're at EOF. Flush the remaining data, if any. */
m_iUncorrelatedPos = m_Channels[0].m_iCorrelatedPos;
return m_iDataBufferAvailFrames;
}
}
/* Starting at our preferred position (m_iUncorrelatedPos), within GetToleranceFrames(),
@@ -214,7 +219,7 @@ bool RageSoundReader_SpeedChange::Step()
c.m_iCorrelatedPos = iBest + m_iUncorrelatedPos;
ASSERT( m_Channels[i].m_iCorrelatedPos + GetWindowSizeFrames() <= m_iDataBufferAvailFrames );
}
return true;
return m_iDataBufferAvailFrames;
}
int RageSoundReader_SpeedChange::GetCursorAvail() const
@@ -247,9 +252,11 @@ int RageSoundReader_SpeedChange::Read( char *buf, int iFrames )
if( iCursorAvail == 0 )
{
Step();
int iRet = Step();
if( iRet < 0 )
return iRet;
if( !GetCursorAvail() )
return 0; // EOF
return END_OF_FILE;
continue;
}