FFmpeg
 All Data Structures Files Functions Variables Typedefs Enumerations Enumerator Macros Groups Pages
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 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 
27 static int apc_probe(AVProbeData *p)
28 {
29  if (!strncmp(p->buf, "CRYO_APC", 8))
30  return AVPROBE_SCORE_MAX;
31 
32  return 0;
33 }
34 
36 {
37  AVIOContext *pb = s->pb;
38  AVStream *st;
39 
40  avio_rl32(pb); /* CRYO */
41  avio_rl32(pb); /* _APC */
42  avio_rl32(pb); /* 1.20 */
43 
44  st = avformat_new_stream(s, NULL);
45  if (!st)
46  return AVERROR(ENOMEM);
47 
50 
51  avio_rl32(pb); /* number of samples */
52  st->codec->sample_rate = avio_rl32(pb);
53 
54  st->codec->extradata_size = 2 * 4;
57  if (!st->codec->extradata)
58  return AVERROR(ENOMEM);
59 
60  /* initial predictor values for adpcm decoder */
61  avio_read(pb, st->codec->extradata, 2 * 4);
62 
63  if (avio_rl32(pb)) {
64  st->codec->channels = 2;
66  } else {
67  st->codec->channels = 1;
69  }
70 
73  * st->codec->sample_rate;
74  st->codec->block_align = 1;
75 
76  return 0;
77 }
78 
79 #define MAX_READ_SIZE 4096
80 
82 {
83  if (av_get_packet(s->pb, pkt, MAX_READ_SIZE) <= 0)
84  return AVERROR(EIO);
85  pkt->flags &= ~AV_PKT_FLAG_CORRUPT;
86  pkt->stream_index = 0;
87  return 0;
88 }
89 
91  .name = "apc",
92  .long_name = NULL_IF_CONFIG_SMALL("CRYO APC"),
93  .read_probe = apc_probe,
94  .read_header = apc_read_header,
95  .read_packet = apc_read_packet,
96 };