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  1. /*
  2.  * CRYO APC audio format demuxer
  3.  * Copyright (c) 2007 Anssi Hannula <anssi.hannula@gmail.com>
  4.  *
  5.  * This file is part of FFmpeg.
  6.  *
  7.  * FFmpeg is free software; you can redistribute it and/or
  8.  * modify it under the terms of the GNU Lesser General Public
  9.  * License as published by the Free Software Foundation; either
  10.  * version 2.1 of the License, or (at your option) any later version.
  11.  *
  12.  * FFmpeg is distributed in the hope that it will be useful,
  13.  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15.  * Lesser General Public License for more details.
  16.  *
  17.  * You should have received a copy of the GNU Lesser General Public
  18.  * License along with FFmpeg; if not, write to the Free Software
  19.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20.  */
  21.  
  22. #include <string.h>
  23.  
  24. #include "libavutil/channel_layout.h"
  25. #include "avformat.h"
  26. #include "internal.h"
  27.  
  28. static int apc_probe(AVProbeData *p)
  29. {
  30.     if (!strncmp(p->buf, "CRYO_APC", 8))
  31.         return AVPROBE_SCORE_MAX;
  32.  
  33.     return 0;
  34. }
  35.  
  36. static int apc_read_header(AVFormatContext *s)
  37. {
  38.     AVIOContext *pb = s->pb;
  39.     AVStream *st;
  40.  
  41.     avio_rl32(pb); /* CRYO */
  42.     avio_rl32(pb); /* _APC */
  43.     avio_rl32(pb); /* 1.20 */
  44.  
  45.     st = avformat_new_stream(s, NULL);
  46.     if (!st)
  47.         return AVERROR(ENOMEM);
  48.  
  49.     st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
  50.     st->codec->codec_id = AV_CODEC_ID_ADPCM_IMA_APC;
  51.  
  52.     avio_rl32(pb); /* number of samples */
  53.     st->codec->sample_rate = avio_rl32(pb);
  54.  
  55.     if (ff_alloc_extradata(st->codec, 2 * 4))
  56.         return AVERROR(ENOMEM);
  57.  
  58.     /* initial predictor values for adpcm decoder */
  59.     avio_read(pb, st->codec->extradata, 2 * 4);
  60.  
  61.     if (avio_rl32(pb)) {
  62.         st->codec->channels       = 2;
  63.         st->codec->channel_layout = AV_CH_LAYOUT_STEREO;
  64.     } else {
  65.         st->codec->channels       = 1;
  66.         st->codec->channel_layout = AV_CH_LAYOUT_MONO;
  67.     }
  68.  
  69.     st->codec->bits_per_coded_sample = 4;
  70.     st->codec->bit_rate = st->codec->bits_per_coded_sample * st->codec->channels
  71.                           * st->codec->sample_rate;
  72.     st->codec->block_align = 1;
  73.  
  74.     return 0;
  75. }
  76.  
  77. #define MAX_READ_SIZE 4096
  78.  
  79. static int apc_read_packet(AVFormatContext *s, AVPacket *pkt)
  80. {
  81.     if (av_get_packet(s->pb, pkt, MAX_READ_SIZE) <= 0)
  82.         return AVERROR(EIO);
  83.     pkt->flags &= ~AV_PKT_FLAG_CORRUPT;
  84.     pkt->stream_index = 0;
  85.     return 0;
  86. }
  87.  
  88. AVInputFormat ff_apc_demuxer = {
  89.     .name           = "apc",
  90.     .long_name      = NULL_IF_CONFIG_SMALL("CRYO APC"),
  91.     .read_probe     = apc_probe,
  92.     .read_header    = apc_read_header,
  93.     .read_packet    = apc_read_packet,
  94. };
  95.