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
  24 #include "libavutil/channel_layout.h"
  25 #include "avformat.h"
  26 #include "demux.h"
  27
  28 static int apc_probe(const 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     int ret;
  41     int channels;
  42
  43     avio_rl32(pb); /* CRYO */
  44     avio_rl32(pb); /* _APC */
  45     avio_rl32(pb); /* 1.20 */
  46
  47     st = avformat_new_stream(s, NULL);
  48     if (!st)
  49         return AVERROR(ENOMEM);
  50
  51     st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
  52     st->codecpar->codec_id = AV_CODEC_ID_ADPCM_IMA_APC;
  53
  54     avio_rl32(pb); /* number of samples */
  55     st->codecpar->sample_rate = avio_rl32(pb);
  56
  57     /* initial predictor values for adpcm decoder */
  58     if ((ret = ff_get_extradata(s, st->codecpar, pb, 2 * 4)) < 0)
  59         return ret;
  60
  61     channels = !!avio_rl32(pb) + 1;
  62     av_channel_layout_default(&st->codecpar->ch_layout, channels);
  63
  64     st->codecpar->bits_per_coded_sample = 4;
  65     st->codecpar->bit_rate = (int64_t)st->codecpar->bits_per_coded_sample * channels
  66                           * st->codecpar->sample_rate;
  67     st->codecpar->block_align = 1;
  68
  69     return 0;
  70 }
  71
  72 #define MAX_READ_SIZE 4096
  73
  74 static int apc_read_packet(AVFormatContext *s, AVPacket *pkt)
  75 {
  76     int ret = av_get_packet(s->pb, pkt, MAX_READ_SIZE);
  77     if (ret < 0)
  78         return ret;
  79     else if (ret == 0)
  80         return AVERROR_INVALIDDATA;
  81     pkt->stream_index = 0;
  82     return 0;
  83 }
  84
  85 const FFInputFormat ff_apc_demuxer = {
  86     .p.name         = "apc",
  87     .p.long_name    = NULL_IF_CONFIG_SMALL("CRYO APC"),
  88     .read_probe     = apc_probe,
  89     .read_header    = apc_read_header,
  90     .read_packet    = apc_read_packet,
  91 };