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aea.c
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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 
24 #include "libavutil/intreadwrite.h"
25 #include "avformat.h"
26 #include "pcm.h"
27 
28 #define AT1_SU_SIZE 212
29 
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 bsm_s, bsm_e, inb_s, inb_e, ch;
38  ch = p->buf[264];
39  bsm_s = p->buf[2048];
40  inb_s = p->buf[2048+1];
41  inb_e = p->buf[2048+210];
42  bsm_e = p->buf[2048+211];
43 
44  if (ch != 1 && ch != 2)
45  return 0;
46 
47  /* Check so that the redundant bsm bytes and info bytes are valid
48  * the block size mode bytes have to be the same
49  * the info bytes have to be the same
50  */
51  if (bsm_s == bsm_e && inb_s == inb_e)
52  return AVPROBE_SCORE_MAX / 4 + 1;
53  }
54  return 0;
55 }
56 
58 {
60  if (!st)
61  return AVERROR(ENOMEM);
62 
63  /* Parse the amount of channels and skip to pos 2048(0x800) */
64  avio_skip(s->pb, 264);
65  st->codec->channels = avio_r8(s->pb);
66  avio_skip(s->pb, 1783);
67 
68 
71  st->codec->sample_rate = 44100;
72  st->codec->bit_rate = 292000;
73 
74  if (st->codec->channels != 1 && st->codec->channels != 2) {
75  av_log(s,AV_LOG_ERROR,"Channels %d not supported!\n",st->codec->channels);
76  return -1;
77  }
78 
80 
82  return 0;
83 }
84 
86 {
87  int ret = av_get_packet(s->pb, pkt, s->streams[0]->codec->block_align);
88 
89  pkt->stream_index = 0;
90  if (ret <= 0)
91  return AVERROR(EIO);
92 
93  return ret;
94 }
95 
97  .name = "aea",
98  .long_name = NULL_IF_CONFIG_SMALL("MD STUDIO audio"),
99  .read_probe = aea_read_probe,
100  .read_header = aea_read_header,
101  .read_packet = aea_read_packet,
102  .read_seek = ff_pcm_read_seek,
103  .flags = AVFMT_GENERIC_INDEX,
104  .extensions = "aea",
105 };