ff733b5f89
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@25040 a1c6a512-1295-4272-9138-f99709370657
166 lines
4.5 KiB
C
166 lines
4.5 KiB
C
/***************************************************************************
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* __________ __ ___.
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* Open \______ \ ____ ____ | | _\_ |__ _______ ___
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* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
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* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
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* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
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* \/ \/ \/ \/ \/
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* $Id$
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*
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* Copyright (C) 2010 Yoshihisa Uchida
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
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* KIND, either express or implied.
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*
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****************************************************************************/
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#include "codeclib.h"
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#include "support_formats.h"
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/*
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* Microsoft ADPCM
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*
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* References
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* [1] Microsoft, New Multimedia Data Types and Data Techniques Revision 3.0, 1994
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* [2] MulitimediaWiki, Microsoft ADPCM, 2006
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* (http://wiki.multimedia.cx/index.php?title=Microsoft_ADPCM)
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* [3] ffmpeg source code, libavcodec/adpcm.c
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*/
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#define ADPCM_NUM_COEFF 7
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static int16_t dec_coeff[2][2];
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static uint16_t delta[2];
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static int16_t sample[2][2];
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static struct pcm_format *fmt;
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static const int16_t adaptation_table[] ICONST_ATTR = {
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230, 230, 230, 230, 307, 409, 512, 614,
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768, 614, 512, 409, 307, 230, 230, 230
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};
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static bool set_format(struct pcm_format *format)
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{
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fmt = format;
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if (fmt->bitspersample != 4)
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{
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DEBUGF("CODEC_ERROR: microsoft adpcm must be 4 bitspersample: %d\n",
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fmt->bitspersample);
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return false;
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}
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fmt->chunksize = fmt->blockalign;
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return true;
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}
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static struct pcm_pos *get_seek_pos(long seek_time,
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uint8_t *(*read_buffer)(size_t *realsize))
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{
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static struct pcm_pos newpos;
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uint32_t newblock = ((uint64_t)seek_time * ci->id3->frequency)
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/ (1000LL * fmt->samplesperblock);
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(void)read_buffer;
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newpos.pos = newblock * fmt->blockalign;
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newpos.samples = newblock * fmt->samplesperblock;
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return &newpos;
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}
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static int16_t create_pcmdata(int ch, uint8_t nibble)
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{
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int32_t pcmdata;
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pcmdata = (sample[ch][0] * dec_coeff[ch][0] +
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sample[ch][1] * dec_coeff[ch][1]) / 256;
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pcmdata += (delta[ch] * (nibble - ((nibble & 0x8) << 1)));
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CLIP(pcmdata, -32768, 32767);
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sample[ch][1] = sample[ch][0];
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sample[ch][0] = pcmdata;
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delta[ch] = (adaptation_table[nibble] * delta[ch]) >> 8;
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if (delta[ch] < 16)
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delta[ch] = 16;
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return (int16_t)pcmdata;
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}
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static int decode(const uint8_t *inbuf, size_t inbufsize,
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int32_t *outbuf, int *outbufcount)
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{
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int ch;
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size_t nsamples = 0;
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int size = fmt->samplesperblock;
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/* read block header */
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for (ch = 0; ch < fmt->channels; ch++)
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{
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if (*inbuf >= ADPCM_NUM_COEFF)
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{
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DEBUGF("CODEC_ERROR: microsoft adpcm illegal initial coeff=%d > 7\n",
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*inbuf);
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return CODEC_ERROR;
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}
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dec_coeff[ch][0] = fmt->coeffs[*inbuf][0];
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dec_coeff[ch][1] = fmt->coeffs[*inbuf][1];
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inbuf++;
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}
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for (ch = 0; ch < fmt->channels; ch++)
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{
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delta[ch] = inbuf[0] | (SE(inbuf[1]) << 8);
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inbuf += 2;
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}
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for (ch = 0; ch < fmt->channels; ch++)
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{
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sample[ch][0] = inbuf[0] | (SE(inbuf[1]) << 8);
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inbuf += 2;
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}
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for (ch = 0; ch < fmt->channels; ch++)
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{
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sample[ch][1] = inbuf[0] | (SE(inbuf[1]) << 8);
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inbuf += 2;
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}
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inbufsize -= 7 * fmt->channels;
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ch = fmt->channels - 1;
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while (size-- > 0)
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{
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*outbuf++ = create_pcmdata(0, *inbuf >> 4 ) << (PCM_OUTPUT_DEPTH - 16);
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*outbuf++ = create_pcmdata(ch, *inbuf & 0xf) << (PCM_OUTPUT_DEPTH - 16);
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nsamples += 2;
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inbuf++;
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inbufsize--;
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if (inbufsize <= 0)
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break;
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}
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if (fmt->channels == 2)
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nsamples >>= 1;
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*outbufcount = nsamples;
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return CODEC_OK;
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}
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static const struct pcm_codec codec = {
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set_format,
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get_seek_pos,
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decode,
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};
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const struct pcm_codec *get_ms_adpcm_codec(void)
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{
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return &codec;
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}
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