libavformat/apc.c

   1 /*
   2  * CRYO APC audio format demuxer
   3  * Copyright (c) 2007 Anssi Hannula <anssi.hannula@gmail.com>
   4  *
   5  * This file is part of Libav.
   6  *
   7  * Libav 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  * Libav 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 Libav; 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
  27 static int apc_probe(AVProbeData *p)
  28 {
  29     if (!strncmp(p->buf, "CRYO_APC", 8))
  30         return AVPROBE_SCORE_MAX;
  31
  32     return 0;
  33 }
  34
  35 static int apc_read_header(AVFormatContext *s)
  36 {
  37     AVIOContext *pb = s->pb;
  38     AVStream *st;
  39
  40     avio_rl32(pb); /* CRYO */
  41     avio_rl32(pb); /* _APC */
  42     avio_rl32(pb); /* 1.20 */
  43
  44     st = avformat_new_stream(s, NULL);
  45     if (!st)
  46         return AVERROR(ENOMEM);
  47
  48     st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
  49     st->codec->codec_id = AV_CODEC_ID_ADPCM_IMA_APC;
  50
  51     avio_rl32(pb); /* number of samples */
  52     st->codec->sample_rate = avio_rl32(pb);
  53
  54     st->codec->extradata_size = 2 * 4;
  55     st->codec->extradata = av_malloc(st->codec->extradata_size +
  56                                      FF_INPUT_BUFFER_PADDING_SIZE);
  57     if (!st->codec->extradata)
  58         return AVERROR(ENOMEM);
  59
  60     /* initial predictor values for adpcm decoder */
  61     avio_read(pb, st->codec->extradata, 2 * 4);
  62
  63     if (avio_rl32(pb)) {
  64         st->codec->channels       = 2;
  65         st->codec->channel_layout = AV_CH_LAYOUT_STEREO;
  66     } else {
  67         st->codec->channels       = 1;
  68         st->codec->channel_layout = AV_CH_LAYOUT_MONO;
  69     }
  70
  71     st->codec->bits_per_coded_sample = 4;
  72     st->codec->bit_rate = st->codec->bits_per_coded_sample * st->codec->channels
  73                           * st->codec->sample_rate;
  74     st->codec->block_align = 1;
  75
  76     return 0;
  77 }
  78
  79 #define MAX_READ_SIZE 4096
  80
  81 static int apc_read_packet(AVFormatContext *s, AVPacket *pkt)
  82 {
  83     if (av_get_packet(s->pb, pkt, MAX_READ_SIZE) <= 0)
  84         return AVERROR(EIO);
  85     pkt->stream_index = 0;
  86     return 0;
  87 }
  88
  89 AVInputFormat ff_apc_demuxer = {
  90     .name           = "apc",
  91     .long_name      = NULL_IF_CONFIG_SMALL("CRYO APC"),
  92     .read_probe     = apc_probe,
  93     .read_header    = apc_read_header,
  94     .read_packet    = apc_read_packet,
  95 };