apps/codecs/libpcm/qt_ima_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 #include "ima_adpcm_common.h"
  24 #include "support_formats.h"
  25
  26 /*
  27  * Apple QuickTime IMA ADPCM
  28  *
  29  * References
  30  * [1] Multimedia Wiki, Apple QuickTime IMA ADPCM
  31  *     URL:http://wiki.multimedia.cx/index.php?title=Apple_QuickTime_IMA_ADPCM
  32  * [2] Apple Inc., Technical Note TN1081 Understanding the Differences Between
  33  *     Apple and Windows IMA-ADPCM Compressed Sound Files, 1996
  34  * [3] ffmpeg source code, libavcodec/adpcm.c
  35  */
  36
  37 static struct pcm_format *fmt;
  38
  39 static bool set_format(struct pcm_format *format)
  40 {
  41     fmt = format;
  42
  43     if (fmt->bitspersample != 4)
  44     {
  45         DEBUGF("CODEC_ERROR: quicktime ima adpcm must be 4 bitspersample: %d\n",
  46                              fmt->bitspersample);
  47         return false;
  48     }
  49
  50     fmt->blockalign = 34 * fmt->channels;
  51     fmt->samplesperblock = 64;
  52
  53     /* chunksize = about 1/50[s] data */
  54     fmt->chunksize = (ci->id3->frequency / (50 * fmt->samplesperblock))
  55                                          * fmt->blockalign;
  56
  57     init_ima_adpcm_decoder(4, NULL);
  58     return true;
  59 }
  60
  61 static struct pcm_pos *get_seek_pos(long seek_time,
  62                                     uint8_t *(*read_buffer)(size_t *realsize))
  63 {
  64     static struct pcm_pos newpos;
  65     uint32_t newblock = ((uint64_t)seek_time * ci->id3->frequency)
  66                                              / (1000LL * fmt->samplesperblock);
  67
  68     (void)read_buffer;
  69     newpos.pos     = newblock * fmt->blockalign;
  70     newpos.samples = newblock * fmt->samplesperblock;
  71     return &newpos;
  72 }
  73
  74 static int decode(const uint8_t *inbuf, size_t inbufsize,
  75                   int32_t *outbuf, int *outbufcount)
  76 {
  77     int ch;
  78     size_t nsamples = 0;
  79     int block_size;
  80     int32_t *pcmbuf;
  81     int32_t init_pcmdata;
  82     int8_t init_index;
  83
  84     while (inbufsize > 0)
  85     {
  86         for (ch = 0; ch < fmt->channels; ch++)
  87         {
  88             /* read block header */
  89             init_pcmdata = (inbuf[0] << 8)|(inbuf[1] & 0x80);
  90             if (init_pcmdata > 32767)
  91                 init_pcmdata -= 65536;
  92
  93             init_index = inbuf[1] & 0x7f;
  94             if (init_index > 88)
  95             {
  96                 DEBUGF("CODEC_ERROR: quicktime ima adpcm illegal step index=%d > 88\n",
  97                                      init_index);
  98                 return CODEC_ERROR;
  99             }
 100
 101             inbuf += 2;
 102             inbufsize -= 2;
 103
 104             set_decode_parameters(1, &init_pcmdata, &init_index);
 105
 106             /* read block data */
 107             pcmbuf = outbuf + ch;
 108             for (block_size = 32; block_size > 0 && inbufsize > 0; block_size--, inbufsize--)
 109             {
 110                 *pcmbuf = create_pcmdata_size4(ch, *inbuf     ) << 13;
 111                 pcmbuf += fmt->channels;
 112                 *pcmbuf = create_pcmdata_size4(ch, *inbuf >> 4) << 13;
 113                 pcmbuf += fmt->channels;
 114                 nsamples += 2;
 115                 inbuf++;
 116             }
 117         }
 118         outbuf += 64 * fmt->channels;
 119     }
 120
 121     if (fmt->channels == 2)
 122         nsamples >>= 1;
 123     *outbufcount = nsamples;
 124
 125     return CODEC_OK;
 126 }
 127
 128 static const struct pcm_codec codec = {
 129                                           set_format,
 130                                           get_seek_pos,
 131                                           decode,
 132                                       };
 133
 134 const struct pcm_codec *get_qt_ima_adpcm_codec(void)
 135 {
 136     return &codec;
 137 }