actions/itgmania212121
1
0
Fork 0
Code Issues Pull Requests Actions 1 Packages Projects Releases Wiki Activity

Both the pitch changer and the resampler quantize the supplied ratio, making

Browse Source 
aligning their speeds very difficult.  The resampler is more limited, and it's easier
to remove this restriction from the speed changer, so reverse this logic, basing
the ratio on the resampler instead of the speed changer.  (also simpler)
This commit is contained in:
Glenn Maynard
2006-12-27 07:46:10 +00:00
parent 76832cad3b
commit 8f9885c229
1 changed files with 7 additions and 21 deletions
Download Patch File Download Diff File Expand all files Collapse all files
stepmania/src/RageSoundReader_PitchChange.cpp
+7 -21
View File
@@ -46,30 +46,16 @@ int RageSoundReader_PitchChange::Read( char *pBuf, int iFrames )
if( m_pSpeedChange->NextReadWillStep() )
{
/* This is the simple way: */
// float fRequestedSpeedRatio = m_fSpeedRatio / m_fPitchRatio;
// m_pSpeedChange->SetSpeedRatio( fRequestedSpeedRatio );
// m_pResample->SetRate( m_fPitchRatio );
// m_pSpeedChange->SetSpeedRatio( m_fSpeedRatio / m_fPitchRatio );
/*
* However, the speed changer has a granularity due to internal fixed-
/* However, the resampler has a limited granularity due to internal fixed-
* point math, and the actual ratio will be slightly different than what
* we tell it to use. The actual ratio used is fActualSpeedChangeRatio.
* Given
*
* fRequestedSpeedRatio = m_fSpeedRatio / m_fPitchRatio
*
* solve for m_fPitchRatio:
*
* fRequestedPitchRatio = m_fSpeedRatio / fRequestedSpeedRatio
*
* and compute the pitch ratio based on the actual speed ratio, rather than
* the requested speed ratio. This avoids excessive rounding error between
* the ratios of m_pSpeedChange and m_pResample.
*/
m_pSpeedChange->SetSpeedRatio( m_fSpeedRatio / m_fPitchRatio );
float fActualSpeedRatio = m_pSpeedChange->GetRatio();
float fRequestedPitchRatio = m_fSpeedRatio / fActualSpeedRatio;
m_pResample->SetRate( fRequestedPitchRatio );
* we tell it to use. The actual ratio used is fActualPitchRatio. */
m_pResample->SetRate( m_fPitchRatio );
float fActualPitchRatio = m_pResample->GetRate();
float fRequestedSpeedRatio = m_fSpeedRatio / fActualPitchRatio;
m_pSpeedChange->SetSpeedRatio( fRequestedSpeedRatio );
}
/* If we just applied a new speed and it caused the ratio to change, return