gstreamer/gst/modplug/libmodplug/changes.txt

changes:
date = 09-feb-2001 [Markus Fick]
-> file: fastmix.cpp
		where: spline creation, spline macros
		what: added unity gain clamp code, added Quantizer_Bits(shift) preprocessor constants
		where: fir creation, fir macros
		what: - removed x<pi/2 condition in coef creation
		      - added quantizer_bits(shift) preprocessor constants
		      - set default quantizer bits to 15 instead 14 (scale now 32768 instead 16384)
		        there should not occure any overflows during fir response calculation because
		        of the symmetric form of filter and the position of the negative fir coefs
		      - changed final volume calculation for 16bit samples (quality enhancement)

date = 08-feb-2001 [Markus Fick]
-> file: sndmix.cpp
		where: function ReadNote()
		what: modified behaviour of modplug so that interpolation is only deactivated if
		      a) the user selects "no interpolation"
			  b) linear interpolation is set and speed incr. > 0xff00
			 => if spline or fir is active then we use always interpolation

-> file: fastmix.cpp
		where: spline macros
		what: changed spline macros to use precalculated tables (way faster)
		where: file
		what: - implemented spline table precalculator
		      - changed fir precalculator + macros (for higher quality and clearer source)
		      - added some comments and documentation
		comment: 
		  - preprocessor constant: SPLINE_FRACBITS
		     ) controls quality/memory usage
			   range is [4..14] inclusive
			   4 = low quality, low memory usage
			   14 = highest quality, highest memory usage (1L<<14)*4*2 bytes
		  - preprocessor constant: WFIR_FRACBITS
		     ) controls quality/memory usage
			   range is [4..12] inclusive
			   4 = low quality, low mu
			   12 = highest quality, highest memory usage ((1L<<(12+1))+1)*8*2 bytes

date = 07-feb-2001 [Markus Fick]
-> file: fastmix.cpp
		where: spline macros
		what: fixed error in coef calculation

date = 07-feb-2001 [Markus Fick]
-> file: sndfile.h
		where: class definition of soundfile 
		what: removed InitFIR + DoneFIR function prototypes
-> file: sndfile.cpp
		function:CSoundFile::CSoundFile()
		what: [modify] removed call to CSoundFile::InitFIRMixer( )

		function:CSoundFile::~CSoundFile()
		what: [modify] removed call to CSoundFile::DoneFIRMixer( )
-> file: fastmix.cpp
		where: spline macros
		what: changed formula + added some guard bits to calculation

		where: fir macros + implementation
		what: - moved CSoundfile::FIR funtions to CzFIR (single instance sfir)
		      - changed fir macros to support CzFIR class

date = 06-feb-2001 [Markus Fick]
-> file: fastmix.cpp
         where: macros
		 what: - removed fir filter with coef interpolation
		       - add spline interpolation
			RM: now modplug->select( SPLINE ) selects spline and
			        modplug->select( POLYPHASE ) selects 8tap fir filter

date = 05-feb-2001 [Markus Fick]
-> file: fastmix.cpp
         where: macros + filter order
         what: [modify] changed filter order to 8 instead of 10

-> file: fastmix.cpp
         what: new macros+switch for fir-interpolator with coef interpolation

date = 04-feb-2001 [Markus Fick]

-> file: sndfile.h
	 where: class CSoundFile (bottom)
	 what: [add] methods for FIR mixer support
	             1. int InitFIRInterpolator( );
				 2. int DoneFIRInterpolator( );

-> file: sndfile.cpp
     function:CSoundFile::CSoundFile()
	 what: [modify] add call to CSoundFile::InitFIRMixer( )
	 
	 function:CSoundFile::~CSoundFile()
	 what: [modify] add call to CSoundFile::DoneFIRMixer( )

-> file:  fastmix.cpp
	 new include: <math.h>
		why: need it for fir-coef calculation
     new function: CSoundFile::InitFIRMixer( ) // initializes fir filter lookup (if necessary)
	 new function: CSoundFile::DoneFIRMixer( ) // decrements ReferenceCounter (for static vars) and deinitializes fir struct (if possible).
	 new defs:
		#define FIRCPWBN 10							// log2 of number of precalculated wings (-(1L<<FIRCPWBN)..(1L<<FIRCPWBN))
		#define FIRLOPOSSHIFT (16-(FIRCPWBN+1))		// shift for lopos of sampleposition -> (16 - FIRCPWBN - 1)
		#define FIRLEN 9							// number(-1) of multiplications per sample
		#define FIRCUT 0.90f						// cutoff of filter
		#define MIXNDX_FIRMIXERSRC  0x20			// src-type for firfilter
	 new vars:
		static signed short *cFirLut;				// lulines
		static int bFirInitialized	= 0;			// initialized?
		static int nFirOrder		= FIRLEN;		// order (modplug has 4smps pre/post extension, so limit this to 9)
		static float nFirFC			= FIRCUT;		// cutoff (normalized to pi/2)
		static int nFirCpw			= (1L<<FIRCPWBN);	// number of precalculted filter lines
		static int nFirUsers		= 0;			// reference counter
	 new macros:
		#define SNDMIX_GETMONOVOL8FIRFILTER
		#define SNDMIX_GETMONOVOL16FIRFILTER
		#define SNDMIX_GETSTEREOVOL8FIRFILTER
		#define SNDMIX_GETSTEREOVOL16FIRFILTER
	new mixer interface macros:
		BEGIN_MIX_INTERFACE(Mono8BitFirFilterMix)
		BEGIN_MIX_INTERFACE(Mono16BitFirFilterMix)
		BEGIN_RAMPMIX_INTERFACE(Mono8BitFirFilterRampMix)
		BEGIN_RAMPMIX_INTERFACE(Mono16BitFirFilterRampMix)
		BEGIN_MIX_INTERFACE(FastMono8BitFirFilterMix)
		BEGIN_MIX_INTERFACE(FastMono16BitFirFilterMix)
		BEGIN_FASTRAMPMIX_INTERFACE(FastMono8BitFirFilterRampMix)
		BEGIN_FASTRAMPMIX_INTERFACE(FastMono16BitFirFilterRampMix)
		BEGIN_MIX_INTERFACE(Stereo8BitFirFilterMix)
		BEGIN_MIX_INTERFACE(Stereo16BitFirFilterMix)
		BEGIN_RAMPMIX_INTERFACE(Stereo8BitFirFilterRampMix)
		BEGIN_RAMPMIX_INTERFACE(Stereo16BitFirFilterRampMix)
		BEGIN_MIX_FLT_INTERFACE(FilterMono8BitFirFilterMix)
		BEGIN_MIX_FLT_INTERFACE(FilterMono16BitFirFilterMix)
		BEGIN_RAMPMIX_FLT_INTERFACE(FilterMono8BitFirFilterRampMix)
		BEGIN_RAMPMIX_FLT_INTERFACE(FilterMono16BitFirFilterRampMix)
		BEGIN_MIX_STFLT_INTERFACE(FilterStereo8BitFirFilterMix)
		BEGIN_MIX_STFLT_INTERFACE(FilterStereo16BitFirFilterMix)
		BEGIN_RAMPMIX_STFLT_INTERFACE(FilterStereo8BitFirFilterRampMix)
		BEGIN_RAMPMIX_STFLT_INTERFACE(FilterStereo16BitFirFilterRampMix)
	modified:
		const LPMIXINTERFACE gpMixFunctionTable[2*2*16] // to hold new fir mixer interface
		const LPMIXINTERFACE gpFastMixFunctionTable[2*2*16] // to hold new fir mixer interface
		functioN: UINT CSoundFile::CreateStereoMix(int count)
			new: 
				if (!(pChannel->dwFlags & CHN_NOIDO))
				{
					// use hq-fir mixer?
					if( ((gdwSoundSetup & (SNDMIX_HQRESAMPLER|SNDMIX_ULTRAHQSRCMODE)) == (SNDMIX_HQRESAMPLER|SNDMIX_ULTRAHQSRCMODE)) ||
						((gdwSoundSetup & (SNDMIX_HQRESAMPLER)) == (SNDMIX_HQRESAMPLER)) )
						nFlags += MIXNDX_FIRMIXERSRC;
					else
						nFlags += MIXNDX_LINEARSRC; // use 
				}
			was:
				if (!(pChannel->dwFlags & CHN_NOIDO))
				{
					nFlags += MIXNDX_LINEARSRC; // use 
				}