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avr.c
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1 /*
2  * AVR demuxer
3  * Copyright (c) 2012 Paul B Mahol
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 "libavutil/intreadwrite.h"
23 #include "avformat.h"
24 #include "internal.h"
25 #include "pcm.h"
26 
27 static int avr_probe(AVProbeData *p)
28 {
29  if (AV_RL32(p->buf) != MKTAG('2', 'B', 'I', 'T'))
30  return 0;
31 
32  if (!AV_RB16(p->buf+12) || AV_RB16(p->buf+12) > 256) // channels
33  return AVPROBE_SCORE_EXTENSION/2;
34  if (AV_RB16(p->buf+14) > 256) // bps
35  return AVPROBE_SCORE_EXTENSION/2;
36 
38 }
39 
41 {
42  uint16_t chan, sign, bps;
43  AVStream *st;
44 
45  st = avformat_new_stream(s, NULL);
46  if (!st)
47  return AVERROR(ENOMEM);
48 
50 
51  avio_skip(s->pb, 4); // magic
52  avio_skip(s->pb, 8); // sample_name
53 
54  chan = avio_rb16(s->pb);
55  if (!chan) {
56  st->codec->channels = 1;
57  } else if (chan == 0xFFFFu) {
58  st->codec->channels = 2;
59  } else {
60  avpriv_request_sample(s, "chan %d", chan);
61  return AVERROR_PATCHWELCOME;
62  }
63 
64  st->codec->bits_per_coded_sample = bps = avio_rb16(s->pb);
65 
66  sign = avio_rb16(s->pb);
67 
68  avio_skip(s->pb, 2); // loop
69  avio_skip(s->pb, 2); // midi
70  avio_skip(s->pb, 1); // replay speed
71 
72  st->codec->sample_rate = avio_rb24(s->pb);
73  avio_skip(s->pb, 4 * 3);
74  avio_skip(s->pb, 2 * 3);
75  avio_skip(s->pb, 20);
76  avio_skip(s->pb, 64);
77 
78  st->codec->codec_id = ff_get_pcm_codec_id(bps, 0, 1, sign);
79  if (st->codec->codec_id == AV_CODEC_ID_NONE) {
80  avpriv_request_sample(s, "Bps %d and sign %d", bps, sign);
81  return AVERROR_PATCHWELCOME;
82  }
83 
84  st->codec->block_align = bps * st->codec->channels / 8;
85 
86  avpriv_set_pts_info(st, 64, 1, st->codec->sample_rate);
87  return 0;
88 }
89 
91  .name = "avr",
92  .long_name = NULL_IF_CONFIG_SMALL("AVR (Audio Visual Research)"),
93  .read_probe = avr_probe,
94  .read_header = avr_read_header,
95  .read_packet = ff_pcm_read_packet,
96  .read_seek = ff_pcm_read_seek,
97  .extensions = "avr",
98  .flags = AVFMT_GENERIC_INDEX,
99 };