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/***************************************************************************
* __________ __ ___.
* Open \______ \ ____ ____ | | _\_ |__ _______ ___
* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
* \/ \/ \/ \/ \/
* $Id$
*
* Copyright (C) 2010 Yoshihisa Uchida
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
****************************************************************************/
#include "codeclib.h"
#include "support_formats.h"
/*
* Microsoft ADPCM
*
* References
* [1] Microsoft, New Multimedia Data Types and Data Techniques Revision 3.0, 1994
* [2] MulitimediaWiki, Microsoft ADPCM, 2006
* (http://wiki.multimedia.cx/index.php?title=Microsoft_ADPCM)
* [3] ffmpeg source code, libavcodec/adpcm.c
*/
#define ADPCM_NUM_COEFF 7
static int16_t dec_coeff[2][2];
static uint16_t delta[2];
static int16_t sample[2][2];
static struct pcm_format *fmt;
static const int16_t adaptation_table[] ICONST_ATTR = {
230, 230, 230, 230, 307, 409, 512, 614,
768, 614, 512, 409, 307, 230, 230, 230
};
static bool set_format(struct pcm_format *format)
{
fmt = format;
if (fmt->bitspersample != 4)
{
DEBUGF("CODEC_ERROR: microsoft adpcm must be 4 bitspersample: %d\n",
fmt->bitspersample);
return false;
}
fmt->chunksize = fmt->blockalign;
return true;
}
static struct pcm_pos *get_seek_pos(long seek_time,
uint8_t *(*read_buffer)(size_t *realsize))
{
static struct pcm_pos newpos;
uint32_t newblock = ((uint64_t)seek_time * ci->id3->frequency)
/ (1000LL * fmt->samplesperblock);
(void)read_buffer;
newpos.pos = newblock * fmt->blockalign;
newpos.samples = newblock * fmt->samplesperblock;
return &newpos;
}
static int16_t create_pcmdata(int ch, uint8_t nibble)
{
int32_t pcmdata;
pcmdata = (sample[ch][0] * dec_coeff[ch][0] +
sample[ch][1] * dec_coeff[ch][1]) / 256;
pcmdata += (delta[ch] * (nibble - ((nibble & 0x8) << 1)));
CLIP(pcmdata, -32768, 32767);
sample[ch][1] = sample[ch][0];
sample[ch][0] = pcmdata;
delta[ch] = (adaptation_table[nibble] * delta[ch]) >> 8;
if (delta[ch] < 16)
delta[ch] = 16;
return (int16_t)pcmdata;
}
static int decode(const uint8_t *inbuf, size_t inbufsize,
int32_t *outbuf, int *outbufcount)
{
int ch;
size_t nsamples = 0;
int size = fmt->samplesperblock;
/* read block header */
for (ch = 0; ch < fmt->channels; ch++)
{
if (*inbuf >= ADPCM_NUM_COEFF)
{
DEBUGF("CODEC_ERROR: microsoft adpcm illegal initial coeff=%d > 7\n",
*inbuf);
return CODEC_ERROR;
}
dec_coeff[ch][0] = fmt->coeffs[*inbuf][0];
dec_coeff[ch][1] = fmt->coeffs[*inbuf][1];
inbuf++;
}
for (ch = 0; ch < fmt->channels; ch++)
{
delta[ch] = inbuf[0] | (SE(inbuf[1]) << 8);
inbuf += 2;
}
for (ch = 0; ch < fmt->channels; ch++)
{
sample[ch][0] = inbuf[0] | (SE(inbuf[1]) << 8);
inbuf += 2;
}
for (ch = 0; ch < fmt->channels; ch++)
{
sample[ch][1] = inbuf[0] | (SE(inbuf[1]) << 8);
inbuf += 2;
}
inbufsize -= 7 * fmt->channels;
ch = fmt->channels - 1;
while (size-- > 0)
{
*outbuf++ = create_pcmdata(0, *inbuf >> 4 ) << (PCM_OUTPUT_DEPTH - 16);
*outbuf++ = create_pcmdata(ch, *inbuf & 0xf) << (PCM_OUTPUT_DEPTH - 16);
nsamples += 2;
inbuf++;
inbufsize--;
if (inbufsize <= 0)
break;
}
if (fmt->channels == 2)
nsamples >>= 1;
*outbufcount = nsamples;
return CODEC_OK;
}
static const struct pcm_codec codec = {
set_format,
get_seek_pos,
decode,
};
const struct pcm_codec *get_ms_adpcm_codec(void)
{
return &codec;
}
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