apps/codecs/libpcm/ms_adpcm.c

   1 /***************************************************************************
   2  *             __________               __   ___.
   3  *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
   4  *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
   5  *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
   6  *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
   7  *                     \/            \/     \/    \/            \/
   8  * $Id$
   9  *
  10  * Copyright (C) 2010 Yoshihisa Uchida
  11  *
  12  * This program is free software; you can redistribute it and/or
  13  * modify it under the terms of the GNU General Public License
  14  * as published by the Free Software Foundation; either version 2
  15  * of the License, or (at your option) any later version.
  16  *
  17  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
  18  * KIND, either express or implied.
  19  *
  20  ****************************************************************************/
  21 #include "codeclib.h"
  22 #include "pcm_common.h"
  23
  24 /*
  25  * Microsoft ADPCM
  26  *
  27  * References
  28  * [1] Microsoft, New Multimedia Data Types and Data Techniques Revision 3.0, 1994
  29  * [2] MulitimediaWiki, Microsoft ADPCM, 2006
  30  * (http://wiki.multimedia.cx/index.php?title=Microsoft_ADPCM)
  31  * [3] ffmpeg source code, libavcodec/adpcm.c
  32  */
  33
  34 #define ADPCM_NUM_COEFF 7
  35
  36 static int16_t dec_coeff[2][2];
  37 static uint16_t delta[2];
  38 static int16_t sample[2][2];
  39
  40 static struct pcm_format *fmt;
  41
  42 static const int16_t adaptation_table[] ICONST_ATTR = {
  43     230, 230, 230, 230, 307, 409, 512, 614,
  44     768, 614, 512, 409, 307, 230, 230, 230
  45 };
  46
  47 static bool set_format(struct pcm_format *format)
  48 {
  49     fmt = format;
  50
  51     if (fmt->bitspersample != 4)
  52     {
  53         DEBUGF("CODEC_ERROR: microsoft adpcm must be 4 bitspersample: %d\n",
  54                              fmt->bitspersample);
  55         return false;
  56     }
  57
  58     fmt->chunksize = fmt->blockalign;
  59
  60     return true;
  61 }
  62
  63 static struct pcm_pos *get_seek_pos(long seek_time,
  64                                     uint8_t *(*read_buffer)(size_t *realsize))
  65 {
  66     static struct pcm_pos newpos;
  67     uint32_t newblock = ((uint64_t)seek_time * ci->id3->frequency)
  68                               / (1000LL * fmt->samplesperblock);
  69
  70     (void)read_buffer;
  71     newpos.pos     = newblock * fmt->blockalign;
  72     newpos.samples = newblock * fmt->samplesperblock;
  73     return &newpos;
  74 }
  75
  76 static int16_t create_pcmdata(int ch, uint8_t nibble)
  77 {
  78     int32_t pcmdata;
  79
  80     pcmdata = (sample[ch][0] * dec_coeff[ch][0] +
  81                sample[ch][1] * dec_coeff[ch][1]) / 256;
  82     pcmdata += (delta[ch] * (nibble - ((nibble & 0x8) << 1)));
  83
  84     CLIP(pcmdata, -32768, 32767);
  85
  86     sample[ch][1] = sample[ch][0];
  87     sample[ch][0] = pcmdata;
  88
  89     delta[ch] = (adaptation_table[nibble] * delta[ch]) >> 8;
  90     if (delta[ch] < 16)
  91         delta[ch] = 16;
  92
  93     return (int16_t)pcmdata;
  94 }
  95
  96 static int decode(const uint8_t *inbuf, size_t inbufsize,
  97                   int32_t *outbuf, int *outbufcount)
  98 {
  99     int ch;
 100     size_t nsamples = 0;
 101     int size = fmt->samplesperblock;
 102
 103     /* read block header */
 104     for (ch = 0; ch < fmt->channels; ch++)
 105     {
 106         if (*inbuf >= ADPCM_NUM_COEFF)
 107         {
 108             DEBUGF("CODEC_ERROR: microsoft adpcm illegal initial coeff=%d > 7\n",
 109                                  *inbuf);
 110             return CODEC_ERROR;
 111         }
 112         dec_coeff[ch][0] = fmt->coeffs[*inbuf][0];
 113         dec_coeff[ch][1] = fmt->coeffs[*inbuf][1];
 114         inbuf++;
 115     }
 116
 117     for (ch = 0; ch < fmt->channels; ch++)
 118     {
 119         delta[ch] = inbuf[0] | (SE(inbuf[1]) << 8);
 120         inbuf += 2;
 121     }
 122
 123     for (ch = 0; ch < fmt->channels; ch++)
 124     {
 125         sample[ch][0] = inbuf[0] | (SE(inbuf[1]) << 8);
 126         inbuf += 2;
 127     }
 128
 129     for (ch = 0; ch < fmt->channels; ch++)
 130     {
 131         sample[ch][1] = inbuf[0] | (SE(inbuf[1]) << 8);
 132         inbuf += 2;
 133     }
 134
 135     inbufsize -= 7 * fmt->channels;
 136     ch = fmt->channels - 1;
 137
 138     while (size-- > 0)
 139     {
 140         *outbuf++ = create_pcmdata(0,  *inbuf >> 4 ) << 13;
 141         *outbuf++ = create_pcmdata(ch, *inbuf & 0xf) << 13;
 142         nsamples += 2;
 143
 144         inbuf++;
 145         inbufsize--;
 146         if (inbufsize <= 0)
 147             break;
 148     }
 149
 150     if (fmt->channels == 2)
 151         nsamples >>= 1;
 152     *outbufcount = nsamples;
 153
 154     return CODEC_OK;
 155 }
 156
 157 static const struct pcm_codec codec = {
 158                                           set_format,
 159                                           get_seek_pos,
 160                                           decode,
 161                                       };
 162
 163 const struct pcm_codec *get_ms_adpcm_codec(void)
 164 {
 165     return &codec;
 166 }