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apc.c
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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 
25 #include "avformat.h"
26 #include "internal.h"
27 
28 static int apc_probe(AVProbeData *p)
29 {
30  if (!strncmp(p->buf, "CRYO_APC", 8))
31  return AVPROBE_SCORE_MAX;
32 
33  return 0;
34 }
35 
37 {
38  AVIOContext *pb = s->pb;
39  AVStream *st;
40 
41  avio_rl32(pb); /* CRYO */
42  avio_rl32(pb); /* _APC */
43  avio_rl32(pb); /* 1.20 */
44 
45  st = avformat_new_stream(s, NULL);
46  if (!st)
47  return AVERROR(ENOMEM);
48 
51 
52  avio_rl32(pb); /* number of samples */
53  st->codec->sample_rate = avio_rl32(pb);
54 
55  if (ff_alloc_extradata(st->codec, 2 * 4))
56  return AVERROR(ENOMEM);
57 
58  /* initial predictor values for adpcm decoder */
59  avio_read(pb, st->codec->extradata, 2 * 4);
60 
61  if (avio_rl32(pb)) {
62  st->codec->channels = 2;
64  } else {
65  st->codec->channels = 1;
67  }
68 
71  * st->codec->sample_rate;
72  st->codec->block_align = 1;
73 
74  return 0;
75 }
76 
77 #define MAX_READ_SIZE 4096
78 
80 {
81  if (av_get_packet(s->pb, pkt, MAX_READ_SIZE) <= 0)
82  return AVERROR(EIO);
83  pkt->flags &= ~AV_PKT_FLAG_CORRUPT;
84  pkt->stream_index = 0;
85  return 0;
86 }
87 
89  .name = "apc",
90  .long_name = NULL_IF_CONFIG_SMALL("CRYO APC"),
91  .read_probe = apc_probe,
92  .read_header = apc_read_header,
93  .read_packet = apc_read_packet,
94 };