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 
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 };
const char * s
Definition: avisynth_c.h:668
#define AV_CH_LAYOUT_STEREO
static int apc_read_packet(AVFormatContext *s, AVPacket *pkt)
Definition: apc.c:81
static AVPacket pkt
Definition: demuxing.c:56
AVStream * avformat_new_stream(AVFormatContext *s, const AVCodec *c)
int av_get_packet(AVIOContext *s, AVPacket *pkt, int size)
int avio_read(AVIOContext *s, unsigned char *buf, int size)
Definition: aviobuf.c:478
unsigned int avio_rl32(AVIOContext *s)
Definition: aviobuf.c:579
#define NULL_IF_CONFIG_SMALL(x)
AVInputFormat ff_apc_demuxer
Definition: apc.c:90
AVCodecContext * codec
Definition: avformat.h:662
unsigned char * buf
Definition: avformat.h:336
#define FF_INPUT_BUFFER_PADDING_SIZE
#define MAX_READ_SIZE
Definition: apc.c:79
NULL
Definition: eval.c:55
enum AVMediaType codec_type
enum AVCodecID codec_id
int sample_rate
samples per second
AVIOContext * pb
Definition: avformat.h:977
void * av_malloc(size_t size)
Definition: mem.c:73
Filter the word “frame” indicates either a video frame or a group of audio as stored in an AVFilterBuffer structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a all references to both lists are replaced with a reference to the intersection And when a single format is eventually chosen for a link amongst the remaining all references to the list are updated That means that if a filter requires that its input and output have the same format amongst a supported all it has to do is use a reference to the same list of formats query_formats can leave some formats unset and return AVERROR(EAGAIN) to cause the negotiation mechanism toagain later.That can be used by filters with complex requirements to use the format negotiated on one link to set the formats supported on another.Buffer references ownership and permissions
#define AVPROBE_SCORE_MAX
maximum score, half of that is used for file-extension-based detection
Definition: avformat.h:340
static int apc_read_header(AVFormatContext *s)
Definition: apc.c:35
#define AV_PKT_FLAG_CORRUPT
The packet content is corrupted.
int channels
number of audio channels
static int apc_probe(AVProbeData *p)
Definition: apc.c:27
const char * name
Definition: avformat.h:461
#define AV_CH_LAYOUT_MONO