apc.c
Go to the documentation of this file.
1 /*
2  * CRYO APC audio format demuxer
3  * Copyright (c) 2007 Anssi Hannula <anssi.hannula@gmail.com>
4  *
5  * This file is part of Libav.
6  *
7  * Libav 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  * Libav 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 Libav; 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 #include "avformat.h"
24 
25 static int apc_probe(AVProbeData *p)
26 {
27  if (!strncmp(p->buf, "CRYO_APC", 8))
28  return AVPROBE_SCORE_MAX;
29 
30  return 0;
31 }
32 
34 {
35  AVIOContext *pb = s->pb;
36  AVStream *st;
37 
38  avio_rl32(pb); /* CRYO */
39  avio_rl32(pb); /* _APC */
40  avio_rl32(pb); /* 1.20 */
41 
42  st = avformat_new_stream(s, NULL);
43  if (!st)
44  return AVERROR(ENOMEM);
45 
48 
49  avio_rl32(pb); /* number of samples */
50  st->codec->sample_rate = avio_rl32(pb);
51 
52  st->codec->extradata_size = 2 * 4;
55  if (!st->codec->extradata)
56  return AVERROR(ENOMEM);
57 
58  /* initial predictor values for adpcm decoder */
59  avio_read(pb, st->codec->extradata, 2 * 4);
60 
61  st->codec->channels = 1;
62  if (avio_rl32(pb))
63  st->codec->channels = 2;
64 
67  * st->codec->sample_rate;
68  st->codec->block_align = 1;
69 
70  return 0;
71 }
72 
73 #define MAX_READ_SIZE 4096
74 
76 {
77  if (av_get_packet(s->pb, pkt, MAX_READ_SIZE) <= 0)
78  return AVERROR(EIO);
79  pkt->stream_index = 0;
80  return 0;
81 }
82 
84  .name = "apc",
85  .long_name = NULL_IF_CONFIG_SMALL("CRYO APC format"),
86  .read_probe = apc_probe,
87  .read_header = apc_read_header,
88  .read_packet = apc_read_packet,
89 };