//==========================================================================;
//
// THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY
// KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A PARTICULAR
// PURPOSE.
//
// Copyright (c) 1992-1999 Microsoft Corporation
//
//--------------------------------------------------------------------------;
//
// imaadpcm.c
//
// Description:
// This file contains encode and decode routines for the IMA's ADPCM
// format. This format is the same format used in Intel's DVI standard.
// Intel has made this algorithm public domain and the IMA has endorsed
// this format as a standard for audio compression.
//
// Implementation notes:
//
// A previous distribution of this codec used a data format which did
// not comply with the IMA standard. For stereo files, the interleaving
// of left and right samples was incorrect: the IMA standard requires
// that a DWORD of left-channel data be followed by a DWORD of right-
// channel data, but the previous implementation of this codec
// interleaved the data at the byte level, with the 4 LSBs being the
// left channel data and the 4 MSBs being the right channel data.
// For mono files, each pair of samples was reversed: the first sample
// was stored in the 4 MSBs rather than the 4 LSBs. This problem is
// fixed during the current release. Note: files compressed by the
// old codec will sound distorted when played back with the new codec,
// and vice versa. Please recompress these files with the new codec,
// since they do not conform to the standard and will not be reproduced
// correctly by hardware codecs, etc.
//
// A previous distribution of this codec had an implementation problem
// which degraded the sound quality of the encoding. This was due to
// the fact that the step index was not properly maintained between
// conversions. This problem has been fixed in the current release.
//
// The codec has been speeded up considerably by breaking
// the encode and decode routines into four separate routines each:
// mono 8-bit, mono 16-bit, stereo 8-bit, and stereo 16-bit. This
// approach is recommended for real-time conversion routines.
//
//==========================================================================;
#include <windows.h>
#include <windowsx.h>
#include <mmsystem.h>
#include <mmreg.h>
#include <msacm.h>
#include <msacmdrv.h>
#include "codec.h"
#include "imaadpcm.h"
#include "debug.h"
//
// This array is used by imaadpcmNextStepIndex to determine the next step
// index to use. The step index is an index to the step[] array, below.
//
const short next_step[16] =
{
-1, -1, -1, -1, 2, 4, 6, 8,
-1, -1, -1, -1, 2, 4, 6, 8
};
//
// This array contains the array of step sizes used to encode the ADPCM
// samples. The step index in each ADPCM block is an index to this array.
//
const short step[89] =
{
7, 8, 9, 10, 11, 12, 13,
14, 16, 17, 19, 21, 23, 25,
28, 31, 34, 37, 41, 45, 50,
55, 60, 66, 73, 80, 88, 97,
107, 118, 130, 143, 157, 173, 190,
209, 230, 253, 279, 307, 337, 371,
408, 449, 494, 544, 598, 658, 724,
796, 876, 963, 1060, 1166, 1282, 1411,
1552, 1707, 1878, 2066, 2272, 2499, 2749,
3024, 3327, 3660, 4026, 4428, 4871, 5358,
5894, 6484, 7132, 7845, 8630, 9493, 10442,
11487, 12635, 13899, 15289, 16818, 18500, 20350,
22385, 24623, 27086, 29794, 32767
};
#ifndef INLINE
#define INLINE __inline
#endif
//--------------------------------------------------------------------------;
//
// DWORD pcmM08BytesToSamples
// DWORD pcmM16BytesToSamples
// DWORD pcmS08BytesToSamples
// DWORD pcmS16BytesToSamples
//
// Description:
// These functions return the number of samples in a buffer of PCM
// of the specified format. For efficiency, it is declared INLINE.
// Note that, depending on the optimization flags, it may not
// actually be implemented as INLINE. Optimizing for speed (-Oxwt)
// will generally obey the INLINE specification.
//
// Arguments:
// DWORD cb: The length of the buffer, in bytes.
//
// Return (DWORD): The length of the buffer in samples.
//
//--------------------------------------------------------------------------;
INLINE DWORD pcmM08BytesToSamples(
DWORD cb
)
{
return cb;
}
INLINE DWORD pcmM16BytesToSamples(
DWORD cb
)
{
return cb / ((DWORD)2);
}
INLINE DWORD pcmS08BytesToSamples(
DWORD cb
)
{
return cb / ((DWORD)2);
}
INLINE DWORD pcmS16BytesToSamples(
DWORD cb
)
{
return cb / ((DWORD)4);
}
#ifdef WIN32
//
// This code assumes that the integer nPredictedSample is 32-bits wide!!!
//
// The following define replaces the pair of calls to the inline functions
// imaadpcmSampleEncode() and imaadpcmSampleDecode which are called in the
// encode routines. There is some redundancy between them which is exploited
// in this define. Because there are two returns (nEncodedSample and
// nPredictedSample), it is more efficient to use a #define rather than an
// inline function which would require a pointer to one of the returns.
//
// Basically, nPredictedSample is calculated based on the lDifference value
// already there, rather than regenerating it through imaadpcmSampleDecode().
//
#define imaadpcmFastEncode(nEncodedSample,nPredictedSample,nInputSample,nStepSize) \
{ \
LONG lDifference; \
\
lDifference = nInputSample - nPredictedSample; \
nEncodedSample = 0; \
if( lDifference<0 ) { \
nEncodedSample = 8; \
lDifference = -lDifference; \
} \
\
if( lDifference >= nStepSize ) { \
nEncodedSample |= 4; \
lDifference -= nStepSize; \
} \
\
nStepSize >>= 1; \
if( lDifference >= nStepSize ) { \
nEncodedSample |= 2; \
lDifference -= nStepSize; \
} \
\
nStepSize >>= 1; \
if( lDifference >= nStepSize ) { \
nEncodedSample |= 1; \
lDifference -= nStepSize; \
} \
\
if( nEncodedSample & 8 ) \
nPredictedSample = nInputSample + lDifference - (nStepSize>>1); \
else \
nPredictedSample = nInputSample - lDifference + (nStepSize>>1); \
\
if( nPredictedSample > 32767 ) \
nPredictedSample = 32767; \
else if( nPredictedSample < -32768 ) \
nPredictedSample = -32768; \
}
#else
//--------------------------------------------------------------------------;
//
// int imaadpcmSampleEncode
//
// Description:
// This routine encodes a single ADPCM sample. For efficiency, it is
// declared INLINE. Note that, depending on the optimization flags,
// it may not actually be implemented as INLINE. Optimizing for speed
// (-Oxwt) will generally obey the INLINE specification.
//
// Arguments:
// int nInputSample: The sample to be encoded.
// int nPredictedSample: The predicted value of nInputSample.
// int nStepSize: The quantization step size for the difference between
// nInputSample and nPredictedSample.
//
// Return (int): The 4-bit ADPCM encoded sample, which corresponds to the
// quantized difference value.
//
//--------------------------------------------------------------------------;
INLINE int imaadpcmSampleEncode
(
int nInputSample,
int nPredictedSample,
int nStepSize
)
{
LONG lDifference; // difference may require 17 bits!
int nEncodedSample;
//
// set sign bit (bit 3 of the encoded sample) based on sign of the
// difference (nInputSample-nPredictedSample). Note that we want the
// absolute value of the difference for the subsequent quantization.
//
lDifference = nInputSample - nPredictedSample;
nEncodedSample = 0;
if( lDifference<0 ) {
nEncodedSample = 8;
lDifference = -lDifference;
}
//
// quantize lDifference sample
//
if( lDifference >= nStepSize ) { // Bit 2.
nEncodedSample |= 4;
lDifference -= nStepSize;
}
nStepSize >>= 1;
if( lDifference >= nStepSize ) { // Bit 1.
nEncodedSample |= 2;
lDifference -= nStepSize;
}
nStepSize >>= 1;
if( lDifference >= nStepSize ) { // Bit 0.
nEncodedSample |= 1;
}
return (nEncodedSample);
}
#endif
//--------------------------------------------------------------------------;
//
// int imaadpcmSampleDecode
//
// Description:
// This routine decodes a single ADPCM sample. For efficiency, it is
// declared INLINE. Note that, depending on the optimization flags,
// it may not actually be implemented as INLINE. Optimizing for speed
// (-Oxwt) will generally obey the INLINE specification.
//
// Arguments:
// int nEncodedSample: The sample to be decoded.
// int nPredictedSample: The predicted value of the sample (in PCM).
// int nStepSize: The quantization step size used to encode the sample.
//
// Return (int): The decoded PCM sample.
//
//--------------------------------------------------------------------------;
INLINE int imaadpcmSampleDecode
(
int nEncodedSample,
int nPredictedSample,
int nStepSize
)
{
LONG lDifference;
LONG lNewSample;
//
// calculate difference:
//
// lDifference = (nEncodedSample + 1/2) * nStepSize / 4
//
lDifference = nStepSize>>3;
if (nEncodedSample & 4)
lDifference += nStepSize;
if (nEncodedSample & 2)
lDifference += nStepSize>>1;
if (nEncodedSample & 1)
lDifference += nStepSize>>2;
//
// If the 'sign bit' of the encoded nibble is set, then the
// difference is negative...
//
if (nEncodedSample & 8)
lDifference = -lDifference;
//
// adjust predicted sample based on calculated difference
//
lNewSample = nPredictedSample + lDifference;
//
// check for overflow and clamp if necessary to a 16 signed sample.
// Note that this is optimized for the most common case, when we
// don't have to clamp.
//
if( (long)(short)lNewSample == lNewSample )
{
return (int)lNewSample;
}
//
// Clamp.
//
if( lNewSample < -32768 )
return (int)-32768;
else
return (int)32767;
}
//--------------------------------------------------------------------------;
//
// int imaadpcmNextStepIndex
//
// Description:
// This routine calculates the step index value to use for the next
// encode, based on the current value of the step index and the current
// encoded sample. For efficiency, it is declared INLINE. Note that,
// depending on the optimization flags, it may not actually be
// implemented as INLINE. Optimizing for speed (-Oxwt) will generally
// obey the INLINE specification.
//
// Arguments:
// int nEncodedSample: The current encoded ADPCM sample.
// int nStepIndex: The step index value used to encode nEncodedSample.
//
// Return (int): The step index to use for the next sample.
//
//--------------------------------------------------------------------------;
INLINE int imaadpcmNextStepIndex
(
int nEncodedSample,
int nStepIndex
)
{
//
// compute new stepsize step
//
nStepIndex += next_step[nEncodedSample];
if (nStepIndex < 0)
nStepIndex = 0;
else if (nStepIndex > 88)
nStepIndex = 88;
return (nStepIndex);
}
//--------------------------------------------------------------------------;
//
// BOOL imaadpcmValidStepIndex
//
// Description:
// This routine checks the step index value to make sure that it is
// within the legal range.
//
// Arguments:
//
// int nStepIndex: The step index value.
//
// Return (BOOL): TRUE if the step index is valid; FALSE otherwise.
//
//--------------------------------------------------------------------------;
INLINE BOOL imaadpcmValidStepIndex
(
int nStepIndex
)
{
if( nStepIndex >= 0 && nStepIndex <= 88 )
return TRUE;
else
return FALSE;
}
//==========================================================================;
//
// DECODE ROUTINES
//
//==========================================================================;
//--------------------------------------------------------------------------;
//
// DWORD imaadpcmDecode4Bit_M08
// DWORD imaadpcmDecode4Bit_M16
// DWORD imaadpcmDecode4Bit_S08
// DWORD imaadpcmDecode4Bit_S16
//
// Description:
// These functions decode a buffer of data from ADPCM to PCM in the
// specified format. The appropriate function is called once for each
// ACMDM_STREAM_CONVERT message received. Note that since these
// functions must share the same prototype as the encoding functions
// (see acmdStreamOpen() and acmdStreamConvert() in codec.c for more
// details), not all the parameters are used by these routines.
//
// Arguments:
// HPBYTE pbSrc: Pointer to the source buffer (ADPCM data).
// DWORD cbSrcLength: The length of the source buffer (in bytes).
// HPBYTE pbDst: Pointer to the destination buffer (PCM data). Note
// that it is assumed that the destination buffer is
// large enough to hold all the encoded data; see
// acmdStreamSize() in codec.c for more details.
// UINT nBlockAlignment: The block alignment of the ADPCM data (in
// bytes).
// UINT cSamplesPerBlock: The number of samples in each ADPCM block;
// not used for decoding.
// int *pnStepIndexL: Pointer to the step index value (left channel)
// in the STREAMINSTANCE structure; not used for
// decoding.
// int *pnStepIndexR: Pointer to the step index value (right channel)
// in the STREAMINSTANCE structure; not used for
// decoding.
//
// Return (DWORD): The number of bytes used in the destination buffer.
//
//--------------------------------------------------------------------------;
DWORD FNGLOBAL imaadpcmDecode4Bit_M08
(
HPBYTE pbSrc,
DWORD cbSrcLength,
HPBYTE pbDst,
UINT nBlockAlignment,
UINT cSamplesPerBlock,
int * pnStepIndexL,
int * pnStepIndexR
)
{
HPBYTE pbDstStart;
UINT cbHeader;
UINT cbBlockLength;
BYTE bSample;
int nStepSize;
int nEncSample;
int nPredSample;
int nStepIndex;
pbDstStart = pbDst;
cbHeader = IMAADPCM_HEADER_LENGTH * 1; // 1 = number of channels.
DPF(3,"Starting imaadpcmDecode4Bit_M08().");
//
//
//
while (cbSrcLength >= cbHeader)
{
DWORD dwHeader;
cbBlockLength = (UINT)min(cbSrcLength, nBlockAlignment);
cbSrcLength -= cbBlockLength;
cbBlockLength -= cbHeader;
//
// block header
//
dwHeader = *(DWORD HUGE_T *)pbSrc;
pbSrc += sizeof(DWORD);
nPredSample = (int)(short)LOWORD(dwHeader);
nStepIndex = (int)(BYTE)HIWORD(dwHeader);
if( !imaadpcmValidStepIndex(nStepIndex) ) {
//
// The step index is out of range - this is considered a fatal
// error as the input stream is corrupted. We fail by returning
// zero bytes converted.
//
DPF(1,"imaadpcmDecode4Bit_M08: invalid step index.");
return 0;
}
//
// write out first sample
//
*pbDst++ = (BYTE)((nPredSample >> 8) + 128);
//
//
//
while (cbBlockLength--)
{
bSample = *pbSrc++;
//
// sample 1
//
nEncSample = (bSample & (BYTE)0x0F);
nStepSize = step[nStepIndex];
nPredSample = imaadpcmSampleDecode(nEncSample, nPredSample, nStepSize);
nStepIndex = imaadpcmNextStepIndex(nEncSample, nStepIndex);
//
// write out sample
//
*pbDst++ = (BYTE)((nPredSample >> 8) + 128);
//
// sample 2
//
nEncSample = (bSample >> 4);
nStepSize = step[nStepIndex];
nPredSample = imaadpcmSampleDecode(nEncSample, nPredSample, nStepSize);
nStepIndex = imaadpcmNextStepIndex(nEncSample, nStepIndex);
//
// write out sample
//
*pbDst++ = (BYTE)((nPredSample >> 8) + 128);
}
}
//
// We return the number of bytes used in the destination. This is
// simply the difference in bytes from where we started.
//
return (DWORD)(pbDst - pbDstStart);
} // imaadpcmDecode4Bit_M08()
//--------------------------------------------------------------------------;
//--------------------------------------------------------------------------;
DWORD FNGLOBAL imaadpcmDecode4Bit_M16
(
HPBYTE pbSrc,
DWORD cbSrcLength,
HPBYTE pbDst,
UINT nBlockAlignment,
UINT cSamplesPerBlock,
int * pnStepIndexL,
int * pnStepIndexR
)
{
HPBYTE pbDstStart;
UINT cbHeader;
UINT cbBlockLength;
BYTE bSample;
int nStepSize;
int nEncSample;
int nPredSample;
int nStepIndex;
pbDstStart = pbDst;
cbHeader = IMAADPCM_HEADER_LENGTH * 1; // 1 = number of channels.
DPF(3,"Starting imaadpcmDecode4Bit_M16().");
//
//
//
while (cbSrcLength >= cbHeader)
{
DWORD dwHeader;
cbBlockLength = (UINT)min(cbSrcLength, nBlockAlignment);
cbSrcLength -= cbBlockLength;
cbBlockLength -= cbHeader;
//
// block header
//
dwHeader = *(DWORD HUGE_T *)pbSrc;
pbSrc += sizeof(DWORD);
nPredSample = (int)(short)LOWORD(dwHeader);
nStepIndex = (int)(BYTE)HIWORD(dwHeader);
if( !imaadpcmValidStepIndex(nStepIndex) ) {
//
// The step index is out of range - this is considered a fatal
// error as the input stream is corrupted. We fail by returning
// zero bytes converted.
//
DPF(1,"imaadpcmDecode4Bit_M16: invalid step index.");
return 0;
}
//
// write out first sample
//
*(short HUGE_T *)pbDst = (short)nPredSample;
pbDst += sizeof(short);
//
//
//
while (cbBlockLength--)
{
bSample = *pbSrc++;
//
// sample 1
//
nEncSample = (bSample & (BYTE)0x0F);
nStepSize = step[nStepIndex];
nPredSample = imaadpcmSampleDecode(nEncSample, nPredSample, nStepSize);
nStepIndex = imaadpcmNextStepIndex(nEncSample, nStepIndex);
//
// write out sample
//
*(short HUGE_T *)pbDst = (short)nPredSample;
pbDst += sizeof(short);
//
// sample 2
//
nEncSample = (bSample >> 4);
nStepSize = step[nStepIndex];
nPredSample = imaadpcmSampleDecode(nEncSample, nPredSample, nStepSize);
nStepIndex = imaadpcmNextStepIndex(nEncSample, nStepIndex);
//
// write out sample
//
*(short HUGE_T *)pbDst = (short)nPredSample;
pbDst += sizeof(short);
}
}
//
// We return the number of bytes used in the destination. This is
// simply the difference in bytes from where we started.
//
return (DWORD)(pbDst - pbDstStart);
} // imaadpcmDecode4Bit_M16()
//--------------------------------------------------------------------------;
//--------------------------------------------------------------------------;
DWORD FNGLOBAL imaadpcmDecode4Bit_S08
(
HPBYTE pbSrc,
DWORD cbSrcLength,
HPBYTE pbDst,
UINT nBlockAlignment,
UINT cSamplesPerBlock,
int * pnStepIndexL,
int * pnStepIndexR
)
{
HPBYTE pbDstStart;
UINT cbHeader;
UINT cbBlockLength;
int nStepSize;
DWORD dwHeader;
DWORD dwLeft;
DWORD dwRight;
int i;
int nEncSampleL;
int nPredSampleL;
int nStepIndexL;
int nEncSampleR;
int nPredSampleR;
int nStepIndexR;
pbDstStart = pbDst;
cbHeader = IMAADPCM_HEADER_LENGTH * 2; // 2 = number of channels.
DPF(3,"Starting imaadpcmDecode4Bit_S08().");
//
//
//
while( 0 != cbSrcLength )
{
//
// The data should always be block aligned.
//
ASSERT( cbSrcLength >= nBlockAlignment );
cbBlockLength = nBlockAlignment;
cbSrcLength -= cbBlockLength;
cbBlockLength -= cbHeader;
//
// LEFT channel header
//
dwHeader = *(DWORD HUGE_T *)pbSrc;
pbSrc += sizeof(DWORD);
nPredSampleL = (int)(short)LOWORD(dwHeader);
nStepIndexL = (int)(BYTE)HIWORD(dwHeader);
if( !imaadpcmValidStepIndex(nStepIndexL) ) {
//
// The step index is out of range - this is considered a fatal
// error as the input stream is corrupted. We fail by returning
// zero bytes converted.
//
DPF(1,"imaadpcmDecode4Bit_S08: invalid step index (L).");
return 0;
}
//
// RIGHT channel header
//
dwHeader = *(DWORD HUGE_T *)pbSrc;
pbSrc += sizeof(DWORD);
nPredSampleR = (int)(short)LOWORD(dwHeader);
nStepIndexR = (int)(BYTE)HIWORD(dwHeader);
if( !imaadpcmValidStepIndex(nStepIndexR) ) {
//
// The step index is out of range - this is considered a fatal
// error as the input stream is corrupted. We fail by returning
// zero bytes converted.
//
DPF(1,"imaadpcmDecode4Bit_S08: invalid step index (R).");
return 0;
}
//
// write out first sample
//
*pbDst++ = (BYTE)((nPredSampleL >> 8) + 128);
*pbDst++ = (BYTE)((nPredSampleR >> 8) + 128);
//
// The first DWORD contains 4 left samples, the second DWORD
// contains 4 right samples. We process the source in 8-byte
// chunks to make it easy to interleave the output correctly.
//
ASSERT( 0 == cbBlockLength%8 );
while( 0 != cbBlockLength )
{
cbBlockLength -= 8;
dwLeft = *(DWORD HUGE_T *)pbSrc;
pbSrc += sizeof(DWORD);
dwRight = *(DWORD HUGE_T *)pbSrc;
pbSrc += sizeof(DWORD);
for( i=8; i>0; i-- )
{
//
// LEFT channel
//
nEncSampleL = (dwLeft & 0x0F);
nStepSize = step[nStepIndexL];
nPredSampleL = imaadpcmSampleDecode(nEncSampleL, nPredSampleL, nStepSize);
nStepIndexL = imaadpcmNextStepIndex(nEncSampleL, nStepIndexL);
//
// RIGHT channel
//
nEncSampleR = (dwRight & 0x0F);
nStepSize = step[nStepIndexR];
nPredSampleR = imaadpcmSampleDecode(nEncSampleR, nPredSampleR, nStepSize);
nStepIndexR = imaadpcmNextStepIndex(nEncSampleR, nStepIndexR);
//
// write out sample
//
*pbDst++ = (BYTE)((nPredSampleL >> 8) + 128);
*pbDst++ = (BYTE)((nPredSampleR >> 8) + 128);
//
// Shift the next input sample into the low-order 4 bits.
//
dwLeft >>= 4;
dwRight >>= 4;
}
}
}
//
// We return the number of bytes used in the destination. This is
// simply the difference in bytes from where we started.
//
return (DWORD)(pbDst - pbDstStart);
} // imaadpcmDecode4Bit_S08()
//--------------------------------------------------------------------------;
//--------------------------------------------------------------------------;
DWORD FNGLOBAL imaadpcmDecode4Bit_S16
(
HPBYTE pbSrc,
DWORD cbSrcLength,
HPBYTE pbDst,
UINT nBlockAlignment,
UINT cSamplesPerBlock,
int * pnStepIndexL,
int * pnStepIndexR
)
{
HPBYTE pbDstStart;
UINT cbHeader;
UINT cbBlockLength;
int nStepSize;
DWORD dwHeader;
DWORD dwLeft;
DWORD dwRight;
int i;
int nEncSampleL;
int nPredSampleL;
int nStepIndexL;
int nEncSampleR;
int nPredSampleR;
int nStepIndexR;
pbDstStart = pbDst;
cbHeader = IMAADPCM_HEADER_LENGTH * 2; // 2 = number of channels.
DPF(3,"Starting imaadpcmDecode4Bit_S16().");
//
//
//
while( 0 != cbSrcLength )
{
//
// The data should always be block aligned.
//
ASSERT( cbSrcLength >= nBlockAlignment );
cbBlockLength = nBlockAlignment;
cbSrcLength -= cbBlockLength;
cbBlockLength -= cbHeader;
//
// LEFT channel header
//
dwHeader = *(DWORD HUGE_T *)pbSrc;
pbSrc += sizeof(DWORD);
nPredSampleL = (int)(short)LOWORD(dwHeader);
nStepIndexL = (int)(BYTE)HIWORD(dwHeader);
if( !imaadpcmValidStepIndex(nStepIndexL) ) {
//
// The step index is out of range - this is considered a fatal
// error as the input stream is corrupted. We fail by returning
// zero bytes converted.
//
DPF(1,"imaadpcmDecode4Bit_S16: invalid step index %u (L).", nStepIndexL);
return 0;
}
//
// RIGHT channel header
//
dwHeader = *(DWORD HUGE_T *)pbSrc;
pbSrc += sizeof(DWORD);
nPredSampleR = (int)(short)LOWORD(dwHeader);
nStepIndexR = (int)(BYTE)HIWORD(dwHeader);
if( !imaadpcmValidStepIndex(nStepIndexR) ) {
//
// The step index is out of range - this is considered a fatal
// error as the input stream is corrupted. We fail by returning
// zero bytes converted.
//
DPF(1,"imaadpcmDecode4Bit_S16: invalid step index %u (R).",nStepIndexR);
return 0;
}
//
// write out first sample
//
*(DWORD HUGE_T *)pbDst = MAKELONG(nPredSampleL, nPredSampleR);
pbDst += sizeof(DWORD);
//
// The first DWORD contains 4 left samples, the second DWORD
// contains 4 right samples. We process the source in 8-byte
// chunks to make it easy to interleave the output correctly.
//
ASSERT( 0 == cbBlockLength%8 );
while( 0 != cbBlockLength )
{
cbBlockLength -= 8;
dwLeft = *(DWORD HUGE_T *)pbSrc;
pbSrc += sizeof(DWORD);
dwRight = *(DWORD HUGE_T *)pbSrc;
pbSrc += sizeof(DWORD);
for( i=8; i>0; i-- )
{
//
// LEFT channel
//
nEncSampleL = (dwLeft & 0x0F);
nStepSize = step[nStepIndexL];
nPredSampleL = imaadpcmSampleDecode(nEncSampleL, nPredSampleL, nStepSize);
nStepIndexL = imaadpcmNextStepIndex(nEncSampleL, nStepIndexL);
//
// RIGHT channel
//
nEncSampleR = (dwRight & 0x0F);
nStepSize = step[nStepIndexR];
nPredSampleR = imaadpcmSampleDecode(nEncSampleR, nPredSampleR, nStepSize);
nStepIndexR = imaadpcmNextStepIndex(nEncSampleR, nStepIndexR);
//
// write out sample
//
*(DWORD HUGE_T *)pbDst = MAKELONG(nPredSampleL, nPredSampleR);
pbDst += sizeof(DWORD);
//
// Shift the next input sample into the low-order 4 bits.
//
dwLeft >>= 4;
dwRight >>= 4;
}
}
}
//
// We return the number of bytes used in the destination. This is
// simply the difference in bytes from where we started.
//
return (DWORD)(pbDst - pbDstStart);
} // imaadpcmDecode4Bit_S16()
//==========================================================================;
//
// ENCODE ROUTINES
//
//==========================================================================;
//--------------------------------------------------------------------------;
//
// DWORD imaadpcmEncode4Bit_M08
// DWORD imaadpcmEncode4Bit_M16
// DWORD imaadpcmEncode4Bit_S08
// DWORD imaadpcmEncode4Bit_S16
//
// Description:
// These functions encode a buffer of data from PCM to ADPCM in the
// specified format. The appropriate function is called once for each
// ACMDM_STREAM_CONVERT message received. Note that since these
// functions must share the same prototype as the decoding functions
// (see acmdStreamOpen() and acmdStreamConvert() in codec.c for more
// details), not all the parameters are used by these routines.
//
// Arguments:
// HPBYTE pbSrc: Pointer to the source buffer (PCM data).
// DWORD cbSrcLength: The length of the source buffer (in bytes).
// HPBYTE pbDst: Pointer to the destination buffer (ADPCM data). Note
// that it is assumed that the destination buffer is
// large enough to hold all the encoded data; see
// acmdStreamSize() in codec.c for more details.
// UINT nBlockAlignment: The block alignment of the ADPCM data (in
// bytes); not used for encoding.
// UINT cSamplesPerBlock: The number of samples in each ADPCM block.
// int *pnStepIndexL: Pointer to the step index value (left channel)
// in the STREAMINSTANCE structure; this is used to
// maintain the step index across converts.
// int *pnStepIndexR: Pointer to the step index value (right channel)
// in the STREAMINSTANCE structure; this is used to
// maintain the step index across converts. It is only
// used for stereo converts.
//
// Return (DWORD): The number of bytes used in the destination buffer.
//
//--------------------------------------------------------------------------;
DWORD FNGLOBAL imaadpcmEncode4Bit_M08
(
HPBYTE pbSrc,
DWORD cbSrcLength,
HPBYTE pbDst,
UINT nBlockAlignment,
UINT cSamplesPerBlock,
int * pnStepIndexL,
int * pnStepIndexR
)
{
HPBYTE pbDstStart;
DWORD cSrcSamples;
UINT cBlockSamples;
int nSample;
int nStepSize;
int nEncSample1;
int nEncSample2;
int nPredSample;
int nStepIndex;
pbDstStart = pbDst;
cSrcSamples = pcmM08BytesToSamples(cbSrcLength);
//
// Restore the Step Index to that of the final convert of the previous
// buffer. Remember to restore this value to psi->nStepIndexL.
//
nStepIndex = (*pnStepIndexL);
//
//
//
//
while (0 != cSrcSamples)
{
cBlockSamples = (UINT)min(cSrcSamples, cSamplesPerBlock);
cSrcSamples -= cBlockSamples;
//
// block header
//
nPredSample = ((short)*pbSrc++ - 128) << 8;
cBlockSamples--;
*(LONG HUGE_T *)pbDst = MAKELONG(nPredSample, nStepIndex);
pbDst += sizeof(LONG);
//
// We have written the header for this block--now write the data
// chunk (which consists of a bunch of encoded nibbles). Note
// that if we don't have enough data to fill a complete byte, then
// we add a 0 nibble on the end.
//
while( cBlockSamples>0 )
{
//
// sample 1
//
nSample = ((short)*pbSrc++ - 128) << 8;
cBlockSamples--;
nStepSize = step[nStepIndex];
imaadpcmFastEncode(nEncSample1,nPredSample,nSample,nStepSize);
nStepIndex = imaadpcmNextStepIndex(nEncSample1, nStepIndex);
//
// sample 2
//
nEncSample2 = 0;
if( cBlockSamples>0 ) {
nSample = ((short)*pbSrc++ - 128) << 8;
cBlockSamples--;
nStepSize = step[nStepIndex];
imaadpcmFastEncode(nEncSample2,nPredSample,nSample,nStepSize);
nStepIndex = imaadpcmNextStepIndex(nEncSample2, nStepIndex);
}
//
// Write out encoded byte.
//
*pbDst++ = (BYTE)(nEncSample1 | (nEncSample2 << 4));
}
}
//
// Restore the value of the Step Index, to be used on the next buffer.
//
(*pnStepIndexL) = nStepIndex;
//
// We return the number of bytes used in the destination. This is
// simply the difference in bytes from where we started.
//
return (DWORD)(pbDst - pbDstStart);
} // imaadpcmEncode4Bit_M08()
//--------------------------------------------------------------------------;
//--------------------------------------------------------------------------;
DWORD FNGLOBAL imaadpcmEncode4Bit_M16
(
HPBYTE pbSrc,
DWORD cbSrcLength,
HPBYTE pbDst,
UINT nBlockAlignment,
UINT cSamplesPerBlock,
int * pnStepIndexL,
int * pnStepIndexR
)
{
HPBYTE pbDstStart;
DWORD cSrcSamples;
UINT cBlockSamples;
int nSample;
int nStepSize;
int nEncSample1;
int nEncSample2;
int nPredSample;
int nStepIndex;
pbDstStart = pbDst;
cSrcSamples = pcmM16BytesToSamples(cbSrcLength);
//
// Restore the Step Index to that of the final convert of the previous
// buffer. Remember to restore this value to psi->nStepIndexL.
//
nStepIndex = (*pnStepIndexL);
//
//
//
//
while (0 != cSrcSamples)
{
cBlockSamples = (UINT)min(cSrcSamples, cSamplesPerBlock);
cSrcSamples -= cBlockSamples;
//
// block header
//
nPredSample = *(short HUGE_T *)pbSrc;
pbSrc += sizeof(short);
cBlockSamples--;
*(LONG HUGE_T *)pbDst = MAKELONG(nPredSample, nStepIndex);
pbDst += sizeof(LONG);
//
// We have written the header for this block--now write the data
// chunk (which consists of a bunch of encoded nibbles). Note
// that if we don't have enough data to fill a complete byte, then
// we add a 0 nibble on the end.
//
while( cBlockSamples>0 )
{
//
// sample 1
//
nSample = *(short HUGE_T *)pbSrc;
pbSrc += sizeof(short);
cBlockSamples--;
nStepSize = step[nStepIndex];
imaadpcmFastEncode(nEncSample1,nPredSample,nSample,nStepSize);
nStepIndex = imaadpcmNextStepIndex(nEncSample1, nStepIndex);
//
// sample 2
//
nEncSample2 = 0;
if( cBlockSamples>0 ) {
nSample = *(short HUGE_T *)pbSrc;
pbSrc += sizeof(short);
cBlockSamples--;
nStepSize = step[nStepIndex];
imaadpcmFastEncode(nEncSample2,nPredSample,nSample,nStepSize);
nStepIndex = imaadpcmNextStepIndex(nEncSample2, nStepIndex);
}
//
// Write out encoded byte.
//
*pbDst++ = (BYTE)(nEncSample1 | (nEncSample2 << 4));
}
}
//
// Restore the value of the Step Index, to be used on the next buffer.
//
(*pnStepIndexL) = nStepIndex;
//
// We return the number of bytes used in the destination. This is
// simply the difference in bytes from where we started.
//
return (DWORD)(pbDst - pbDstStart);
} // imaadpcmEncode4Bit_M16()
//--------------------------------------------------------------------------;
//--------------------------------------------------------------------------;
DWORD FNGLOBAL imaadpcmEncode4Bit_S08
(
HPBYTE pbSrc,
DWORD cbSrcLength,
HPBYTE pbDst,
UINT nBlockAlignment,
UINT cSamplesPerBlock,
int * pnStepIndexL,
int * pnStepIndexR
)
{
HPBYTE pbDstStart;
DWORD cSrcSamples;
UINT cBlockSamples;
int nSample;
int nStepSize;
DWORD dwLeft;
DWORD dwRight;
int i;
int nEncSampleL;
int nPredSampleL;
int nStepIndexL;
int nEncSampleR;
int nPredSampleR;
int nStepIndexR;
pbDstStart = pbDst;
cSrcSamples = pcmS08BytesToSamples(cbSrcLength);
//
// Restore the Step Index to that of the final convert of the previous
// buffer. Remember to restore this value to psi->nStepIndexL,R.
//
nStepIndexL = (*pnStepIndexL);
nStepIndexR = (*pnStepIndexR);
//
//
//
//
while( 0 != cSrcSamples )
{
//
// The samples should always be block aligned.
//
ASSERT( cSrcSamples >= cSamplesPerBlock );
cBlockSamples = cSamplesPerBlock;
cSrcSamples -= cBlockSamples;
//
// LEFT channel block header
//
nPredSampleL = ((short)*pbSrc++ - 128) << 8;
*(LONG HUGE_T *)pbDst = MAKELONG(nPredSampleL, nStepIndexL);
pbDst += sizeof(LONG);
//
// RIGHT channel block header
//
nPredSampleR = ((short)*pbSrc++ - 128) << 8;
*(LONG HUGE_T *)pbDst = MAKELONG(nPredSampleR, nStepIndexR);
pbDst += sizeof(LONG);
cBlockSamples--; // One sample is in the header.
//
// We have written the header for this block--now write the data
// chunk. This consists of 8 left samples (one DWORD of output)
// followed by 8 right samples (also one DWORD). Since the input
// samples are interleaved, we create the left and right DWORDs
// sample by sample, and then write them both out.
//
ASSERT( 0 == cBlockSamples%8 );
while( 0 != cBlockSamples )
{
cBlockSamples -= 8;
dwLeft = 0;
dwRight = 0;
for( i=0; i<8; i++ )
{
//
// LEFT channel
//
nSample = ((short)*pbSrc++ - 128) << 8;
nStepSize = step[nStepIndexL];
imaadpcmFastEncode(nEncSampleL,nPredSampleL,nSample,nStepSize);
nStepIndexL = imaadpcmNextStepIndex(nEncSampleL, nStepIndexL);
dwLeft |= ((DWORD)nEncSampleL) << 4*i;
//
// RIGHT channel
//
nSample = ((short)*pbSrc++ - 128) << 8;
nStepSize = step[nStepIndexR];
imaadpcmFastEncode(nEncSampleR,nPredSampleR,nSample,nStepSize);
nStepIndexR = imaadpcmNextStepIndex(nEncSampleR, nStepIndexR);
dwRight |= ((DWORD)nEncSampleR) << 4*i;
}
//
// Write out encoded DWORDs.
//
*(DWORD HUGE_T *)pbDst = dwLeft;
pbDst += sizeof(DWORD);
*(DWORD HUGE_T *)pbDst = dwRight;
pbDst += sizeof(DWORD);
}
}
//
// Restore the value of the Step Index, to be used on the next buffer.
//
(*pnStepIndexL) = nStepIndexL;
(*pnStepIndexR) = nStepIndexR;
//
// We return the number of bytes used in the destination. This is
// simply the difference in bytes from where we started.
//
return (DWORD)(pbDst - pbDstStart);
} // imaadpcmEncode4Bit_S08()
//--------------------------------------------------------------------------;
//--------------------------------------------------------------------------;
DWORD FNGLOBAL imaadpcmEncode4Bit_S16
(
HPBYTE pbSrc,
DWORD cbSrcLength,
HPBYTE pbDst,
UINT nBlockAlignment,
UINT cSamplesPerBlock,
int * pnStepIndexL,
int * pnStepIndexR
)
{
HPBYTE pbDstStart;
DWORD cSrcSamples;
UINT cBlockSamples;
int nSample;
int nStepSize;
DWORD dwLeft;
DWORD dwRight;
int i;
int nEncSampleL;
int nPredSampleL;
int nStepIndexL;
int nEncSampleR;
int nPredSampleR;
int nStepIndexR;
pbDstStart = pbDst;
cSrcSamples = pcmS16BytesToSamples(cbSrcLength);
//
// Restore the Step Index to that of the final convert of the previous
// buffer. Remember to restore this value to psi->nStepIndexL,R.
//
nStepIndexL = (*pnStepIndexL);
nStepIndexR = (*pnStepIndexR);
//
//
//
//
while( 0 != cSrcSamples )
{
//
// The samples should always be block aligned.
//
ASSERT( cSrcSamples >= cSamplesPerBlock );
cBlockSamples = cSamplesPerBlock;
cSrcSamples -= cBlockSamples;
//
// LEFT channel block header
//
nPredSampleL = *(short HUGE_T *)pbSrc;
pbSrc += sizeof(short);
*(LONG HUGE_T *)pbDst = MAKELONG(nPredSampleL, nStepIndexL);
pbDst += sizeof(LONG);
//
// RIGHT channel block header
//
nPredSampleR = *(short HUGE_T *)pbSrc;
pbSrc += sizeof(short);
*(LONG HUGE_T *)pbDst = MAKELONG(nPredSampleR, nStepIndexR);
pbDst += sizeof(LONG);
cBlockSamples--; // One sample is in the header.
//
// We have written the header for this block--now write the data
// chunk. This consists of 8 left samples (one DWORD of output)
// followed by 8 right samples (also one DWORD). Since the input
// samples are interleaved, we create the left and right DWORDs
// sample by sample, and then write them both out.
//
ASSERT( 0 == cBlockSamples%8 );
while( 0 != cBlockSamples )
{
cBlockSamples -= 8;
dwLeft = 0;
dwRight = 0;
for( i=0; i<8; i++ )
{
//
// LEFT channel
//
nSample = *(short HUGE_T *)pbSrc;
pbSrc += sizeof(short);
nStepSize = step[nStepIndexL];
imaadpcmFastEncode(nEncSampleL,nPredSampleL,nSample,nStepSize);
nStepIndexL = imaadpcmNextStepIndex(nEncSampleL, nStepIndexL);
dwLeft |= ((DWORD)nEncSampleL) << 4*i;
//
// RIGHT channel
//
nSample = *(short HUGE_T *)pbSrc;
pbSrc += sizeof(short);
nStepSize = step[nStepIndexR];
imaadpcmFastEncode(nEncSampleR,nPredSampleR,nSample,nStepSize);
nStepIndexR = imaadpcmNextStepIndex(nEncSampleR, nStepIndexR);
dwRight |= ((DWORD)nEncSampleR) << 4*i;
}
//
// Write out encoded DWORDs.
//
*(DWORD HUGE_T *)pbDst = dwLeft;
pbDst += sizeof(DWORD);
*(DWORD HUGE_T *)pbDst = dwRight;
pbDst += sizeof(DWORD);
}
}
//
// Restore the value of the Step Index, to be used on the next buffer.
//
(*pnStepIndexL) = nStepIndexL;
(*pnStepIndexR) = nStepIndexR;
//
// We return the number of bytes used in the destination. This is
// simply the difference in bytes from where we started.
//
return (DWORD)(pbDst - pbDstStart);
} // imaadpcmEncode4Bit_S16()