libavformat/aea.c

   1 /*
   2  * MD STUDIO audio demuxer
   3  *
   4  * Copyright (c) 2009 Benjamin Larsson
   5  *
   6  * This file is part of FFmpeg.
   7  *
   8  * FFmpeg is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; either
  11  * version 2.1 of the License, or (at your option) any later version.
  12  *
  13  * FFmpeg is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with FFmpeg; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21  */
  22
  23 #include "libavutil/channel_layout.h"
  24 #include "libavutil/intreadwrite.h"
  25 #include "avformat.h"
  26 #include "pcm.h"
  27
  28 #define AT1_SU_SIZE     212
  29
  30 static int aea_read_probe(AVProbeData *p)
  31 {
  32     if (p->buf_size <= 2048+212)
  33         return 0;
  34
  35     /* Magic is '00 08 00 00' in little-endian*/
  36     if (AV_RL32(p->buf)==0x800) {
  37         int ch, i;
  38         ch = p->buf[264];
  39
  40         if (ch != 1 && ch != 2)
  41             return 0;
  42
  43         /* Check so that the redundant bsm bytes and info bytes are valid
  44          * the block size mode bytes have to be the same
  45          * the info bytes have to be the same
  46          */
  47         for (i = 2048; i + 211 < p->buf_size; i+= 212) {
  48             int bsm_s, bsm_e, inb_s, inb_e;
  49             bsm_s = p->buf[0];
  50             inb_s = p->buf[1];
  51             inb_e = p->buf[210];
  52             bsm_e = p->buf[211];
  53
  54             if (bsm_s != bsm_e || inb_s != inb_e)
  55                 return 0;
  56         }
  57         return AVPROBE_SCORE_MAX / 4 + 1;
  58     }
  59     return 0;
  60 }
  61
  62 static int aea_read_header(AVFormatContext *s)
  63 {
  64     AVStream *st = avformat_new_stream(s, NULL);
  65     if (!st)
  66         return AVERROR(ENOMEM);
  67
  68     /* Parse the amount of channels and skip to pos 2048(0x800) */
  69     avio_skip(s->pb, 264);
  70     st->codecpar->channels = avio_r8(s->pb);
  71     avio_skip(s->pb, 1783);
  72
  73
  74     st->codecpar->codec_type     = AVMEDIA_TYPE_AUDIO;
  75     st->codecpar->codec_id       = AV_CODEC_ID_ATRAC1;
  76     st->codecpar->sample_rate    = 44100;
  77     st->codecpar->bit_rate       = 292000;
  78
  79     if (st->codecpar->channels != 1 && st->codecpar->channels != 2) {
  80         av_log(s, AV_LOG_ERROR, "Channels %d not supported!\n", st->codecpar->channels);
  81         return AVERROR_INVALIDDATA;
  82     }
  83
  84     st->codecpar->channel_layout = (st->codecpar->channels == 1) ? AV_CH_LAYOUT_MONO : AV_CH_LAYOUT_STEREO;
  85
  86     st->codecpar->block_align = AT1_SU_SIZE * st->codecpar->channels;
  87     return 0;
  88 }
  89
  90 static int aea_read_packet(AVFormatContext *s, AVPacket *pkt)
  91 {
  92     int ret = av_get_packet(s->pb, pkt, s->streams[0]->codecpar->block_align);
  93
  94     pkt->stream_index = 0;
  95     if (ret <= 0)
  96         return AVERROR(EIO);
  97
  98     return ret;
  99 }
 100
 101 AVInputFormat ff_aea_demuxer = {
 102     .name           = "aea",
 103     .long_name      = NULL_IF_CONFIG_SMALL("MD STUDIO audio"),
 104     .read_probe     = aea_read_probe,
 105     .read_header    = aea_read_header,
 106     .read_packet    = aea_read_packet,
 107     .read_seek      = ff_pcm_read_seek,
 108     .flags          = AVFMT_GENERIC_INDEX,
 109     .extensions     = "aea",
 110 };