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Fix IMA-ADPCM encoding for AIFF files

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Closes: https://github.com/erikd/libsndfile/pull/516
This commit is contained in:
Leland Lucius 2020-03-16 10:02:46 -05:00 committed by Erik de Castro Lopo
parent 49b7d619a8
commit bbe1975e1f
1 changed files with 52 additions and 54 deletions
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106
src/ima_adpcm.c
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@ -1,5 +1,5 @@
/*
** Copyright (C) 1999-2016 Erik de Castro Lopo <erikd@mega-nerd.com>
** Copyright (C) 1999-2020 Erik de Castro Lopo <erikd@mega-nerd.com>
**
** This program is free software; you can redistribute it and/or modify
** it under the terms of the GNU Lesser General Public License as published by
@ -325,73 +325,58 @@ aiff_ima_encode_block (SF_PRIVATE *psf, IMA_ADPCM_PRIVATE *pima)
{ int chan, k, step, diff, vpdiff, blockindx, indx ;
short bytecode, mask ;
/* Encode the block header. */
k = 0 ;
for (chan = 0 ; chan < pima->channels ; chan ++)
{ blockindx = chan * pima->blocksize ;
/* Encode the block header. */
pima->block [blockindx++] = (pima->previous [chan] >> 8) & 0xFF ;
pima->block [blockindx++] = (pima->previous [chan] & 0x80) + (pima->stepindx [chan] & 0x7F) ;
pima->block [blockindx] = (pima->samples [chan] >> 8) & 0xFF ;
pima->block [blockindx + 1] = (pima->samples [chan] & 0x80) + (pima->stepindx [chan] & 0x7F) ;
/* Encode the samples as 4 bit. */
for (indx = chan ; indx < pima->samplesperblock * pima->channels ; indx += pima->channels)
{ diff = pima->samples [indx] - pima->previous [chan] ;
pima->previous [chan] = pima->samples [chan] ;
} ;
/* Encode second and later samples for every block as a 4 bit value. */
for (k = pima->channels ; k < (pima->samplesperblock * pima->channels) ; k ++)
{ chan = (pima->channels > 1) ? (k % 2) : 0 ;
diff = pima->samples [k] - pima->previous [chan] ;
bytecode = 0 ;
step = ima_step_size [pima->stepindx [chan]] ;
vpdiff = step >> 3 ;
if (diff < 0)
{ bytecode = 8 ;
diff = -diff ;
} ;
mask = 4 ;
while (mask)
{ if (diff >= step)
{ bytecode |= mask ;
diff -= step ;
vpdiff += step ;
bytecode = 0 ;
step = ima_step_size [pima->stepindx [chan]] ;
vpdiff = step >> 3 ;
if (diff < 0)
{ bytecode = 8 ;
diff = -diff ;
} ;
mask = 4 ;
while (mask)
{ if (diff >= step)
{ bytecode |= mask ;
diff -= step ;
vpdiff += step ;
} ;
step >>= 1 ;
mask >>= 1 ;
} ;
step >>= 1 ;
mask >>= 1 ;
} ;
if (bytecode & 8)
pima->previous [chan] -= vpdiff ;
else
if (bytecode & 8)
vpdiff = -vpdiff ;
pima->previous [chan] += vpdiff ;
if (pima->previous [chan] > 32767)
pima->previous [chan] = 32767 ;
else if (pima->previous [chan] < -32768)
pima->previous [chan] = -32768 ;
if (pima->previous [chan] > 32767)
pima->previous [chan] = 32767 ;
else if (pima->previous [chan] < -32768)
pima->previous [chan] = -32768 ;
pima->stepindx [chan] += ima_indx_adjust [bytecode] ;
pima->stepindx [chan] += ima_indx_adjust [bytecode] ;
pima->stepindx [chan] = clamp_ima_step_index (pima->stepindx [chan]) ;
pima->samples [k] = bytecode ;
} ;
/* Pack the 4 bit encoded samples. */
for (chan = 0 ; chan < pima->channels ; chan ++)
{ for (indx = pima->channels ; indx < pima->channels * pima->samplesperblock ; indx += 2 * pima->channels)
{ blockindx = chan * pima->blocksize + 2 + indx / 2 ;
pima->block [blockindx] = pima->samples [indx] & 0x0F ;
pima->block [blockindx] |= (pima->samples [indx + chan] << 4) & 0xF0 ;
pima->stepindx [chan] = clamp_ima_step_index (pima->stepindx [chan]) ;
pima->block [blockindx] = (bytecode << (4 * k)) | pima->block [blockindx] ;
blockindx += k ;
k = 1 - k ;
} ;
} ;
/* Write the block to disk. */
if ((k = psf_fwrite (pima->block, 1, pima->channels * pima->blocksize, psf)) != pima->channels * pima->blocksize)
psf_log_printf (psf, "*** Warning : short write (%d != %d).\n", k, pima->channels * pima->blocksize) ;
memset (pima->samples, 0, pima->channels * pima->samplesperblock * sizeof (short)) ;
memset (pima->block, 0, pima->channels * pima->blocksize) ;
pima->samplecount = 0 ;
pima->blockcount ++ ;
@ -779,9 +764,9 @@ wavlike_ima_seek (SF_PRIVATE *psf, int mode, sf_count_t offset)
if (offset == 0)
{ psf_fseek (psf, psf->dataoffset, SEEK_SET) ;
pima->blockcount = 0 ;
if (!pima->decode_block) {
if (!pima->decode_block)
return PSF_SEEK_ERROR ;
}
pima->decode_block (psf, pima) ;
pima->samplecount = 0 ;
return 0 ;
@ -823,7 +808,20 @@ ima_writer_init (SF_PRIVATE *psf, int blockalign)
if (psf->file.mode != SFM_WRITE)
return SFE_BAD_MODE_RW ;
samplesperblock = 2 * (blockalign - 4 * psf->sf.channels) / psf->sf.channels + 1 ;
switch (SF_CONTAINER (psf->sf.format))
{ case SF_FORMAT_WAV :
case SF_FORMAT_W64 :
samplesperblock = 2 * (blockalign - 4 * psf->sf.channels) / psf->sf.channels + 1 ;
break ;
case SF_FORMAT_AIFF :
samplesperblock = 2 * ((blockalign - 2) * psf->sf.channels) / psf->sf.channels ;
break ;
default :
psf_log_printf (psf, "ima_reader_init: bad psf->sf.format\n") ;
return SFE_INTERNAL ;
} ;
pimasize = sizeof (IMA_ADPCM_PRIVATE) + blockalign + 3 * psf->sf.channels * samplesperblock ;