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 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 #include "avformat.h"
  24
  25 static int apc_probe(AVProbeData *p)
  26 {
  27     if (!strncmp(p->buf, "CRYO_APC", 8))
  28         return AVPROBE_SCORE_MAX;
  29
  30     return 0;
  31 }
  32
  33 static int apc_read_header(AVFormatContext *s, AVFormatParameters *ap)
  34 {
  35     ByteIOContext *pb = s->pb;
  36     AVStream *st;
  37
  38     get_le32(pb); /* CRYO */
  39     get_le32(pb); /* _APC */
  40     get_le32(pb); /* 1.20 */
  41
  42     st = av_new_stream(s, 0);
  43     if (!st)
  44         return AVERROR(ENOMEM);
  45
  46     st->codec->codec_type = CODEC_TYPE_AUDIO;
  47     st->codec->codec_id = CODEC_ID_ADPCM_IMA_WS;
  48
  49     get_le32(pb); /* number of samples */
  50     st->codec->sample_rate = get_le32(pb);
  51
  52     st->codec->extradata_size = 2 * 4;
  53     st->codec->extradata = av_malloc(st->codec->extradata_size +
  54                                      FF_INPUT_BUFFER_PADDING_SIZE);
  55     if (!st->codec->extradata)
  56         return AVERROR(ENOMEM);
  57
  58     /* initial predictor values for adpcm decoder */
  59     get_buffer(pb, st->codec->extradata, 2 * 4);
  60
  61     st->codec->channels = 1;
  62     if (get_le32(pb))
  63         st->codec->channels = 2;
  64
  65     st->codec->bits_per_coded_sample = 4;
  66     st->codec->bit_rate = st->codec->bits_per_coded_sample * st->codec->channels
  67                           * st->codec->sample_rate;
  68     st->codec->block_align = 1;
  69
  70     return 0;
  71 }
  72
  73 #define MAX_READ_SIZE 4096
  74
  75 static int apc_read_packet(AVFormatContext *s, AVPacket *pkt)
  76 {
  77     if (av_get_packet(s->pb, pkt, MAX_READ_SIZE) <= 0)
  78         return AVERROR(EIO);
  79     pkt->stream_index = 0;
  80     return 0;
  81 }
  82
  83 AVInputFormat apc_demuxer = {
  84     "apc",
  85     NULL_IF_CONFIG_SMALL("CRYO APC format"),
  86     0,
  87     apc_probe,
  88     apc_read_header,
  89     apc_read_packet,
  90 };