FFmpeg  4.3.6
gsmdec.c
Go to the documentation of this file.
1 /*
2  * RAW GSM demuxer
3  * Copyright (c) 2011 Justin Ruggles
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 
23 #include "libavutil/mathematics.h"
24 #include "libavutil/opt.h"
25 #include "avformat.h"
26 #include "internal.h"
27 
28 #define GSM_BLOCK_SIZE 33
29 #define GSM_BLOCK_SAMPLES 160
30 #define GSM_SAMPLE_RATE 8000
31 
32 typedef struct GSMDemuxerContext {
33  AVClass *class;
36 
37 static int gsm_probe(const AVProbeData *p)
38 {
39  int valid = 0, invalid = 0;
40  uint8_t *b = p->buf;
41  while (b < p->buf + p->buf_size - 32) {
42  if ((*b & 0xf0) == 0xd0) {
43  valid++;
44  } else {
45  invalid++;
46  }
47  b += 33;
48  }
49  if (valid >> 5 > invalid)
50  return AVPROBE_SCORE_EXTENSION + 1;
51  return 0;
52 }
53 
55 {
56  int ret, size;
57 
58  size = GSM_BLOCK_SIZE;
59 
60  pkt->pos = avio_tell(s->pb);
61  pkt->stream_index = 0;
62 
63  ret = av_get_packet(s->pb, pkt, size);
64  if (ret < GSM_BLOCK_SIZE) {
65  return ret < 0 ? ret : AVERROR(EIO);
66  }
67  pkt->duration = 1;
68  pkt->pts = pkt->pos / GSM_BLOCK_SIZE;
69 
70  return 0;
71 }
72 
74 {
77  if (!st)
78  return AVERROR(ENOMEM);
79 
82  st->codecpar->channels = 1;
86 
88 
89  return 0;
90 }
91 
92 static const AVOption options[] = {
93  { "sample_rate", "", offsetof(GSMDemuxerContext, sample_rate),
94  AV_OPT_TYPE_INT, {.i64 = GSM_SAMPLE_RATE}, 1, INT_MAX / GSM_BLOCK_SIZE,
96  { NULL },
97 };
98 
99 static const AVClass gsm_class = {
100  .class_name = "gsm demuxer",
101  .item_name = av_default_item_name,
102  .option = options,
103  .version = LIBAVUTIL_VERSION_INT,
104 };
105 
107  .name = "gsm",
108  .long_name = NULL_IF_CONFIG_SMALL("raw GSM"),
109  .priv_data_size = sizeof(GSMDemuxerContext),
114  .extensions = "gsm",
115  .raw_codec_id = AV_CODEC_ID_GSM,
116  .priv_class = &gsm_class,
117 };
#define NULL
Definition: coverity.c:32
int size
AVOption.
Definition: opt.h:246
#define LIBAVUTIL_VERSION_INT
Definition: version.h:85
int64_t pos
byte position in stream, -1 if unknown
Definition: packet.h:375
void avpriv_set_pts_info(AVStream *s, int pts_wrap_bits, unsigned int pts_num, unsigned int pts_den)
Set the time base and wrapping info for a given stream.
Definition: utils.c:4948
enum AVCodecID codec_id
Specific type of the encoded data (the codec used).
Definition: codec_par.h:60
static const AVOption options[]
Definition: gsmdec.c:92
const char * b
Definition: vf_curves.c:116
const char * av_default_item_name(void *ptr)
Return the context name.
Definition: log.c:235
static AVPacket pkt
Format I/O context.
Definition: avformat.h:1351
const char * class_name
The name of the class; usually it is the same name as the context structure type to which the AVClass...
Definition: log.h:72
uint8_t
AVOptions.
int64_t duration
Duration of this packet in AVStream->time_base units, 0 if unknown.
Definition: packet.h:373
#define GSM_BLOCK_SIZE
Definition: gsmdec.c:28
AVStream * avformat_new_stream(AVFormatContext *s, const AVCodec *c)
Add a new stream to a media file.
Definition: utils.c:4526
int av_get_packet(AVIOContext *s, AVPacket *pkt, int size)
Allocate and read the payload of a packet and initialize its fields with default values.
Definition: utils.c:307
static av_always_inline int64_t avio_tell(AVIOContext *s)
ftell() equivalent for AVIOContext.
Definition: avio.h:557
uint64_t channel_layout
Audio only.
Definition: codec_par.h:162
int64_t bit_rate
The average bitrate of the encoded data (in bits per second).
Definition: codec_par.h:89
#define AVERROR(e)
Definition: error.h:43
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:188
ff_const59 struct AVInputFormat * iformat
The input container format.
Definition: avformat.h:1363
static const AVClass gsm_class
Definition: gsmdec.c:99
enum AVMediaType codec_type
General type of the encoded data.
Definition: codec_par.h:56
static int gsm_probe(const AVProbeData *p)
Definition: gsmdec.c:37
int buf_size
Size of buf except extra allocated bytes.
Definition: avformat.h:444
unsigned char * buf
Buffer must have AVPROBE_PADDING_SIZE of extra allocated bytes filled with zero.
Definition: avformat.h:443
audio channel layout utility functions
#define s(width, name)
Definition: cbs_vp9.c:257
#define GSM_SAMPLE_RATE
Definition: gsmdec.c:30
static int gsm_read_header(AVFormatContext *s)
Definition: gsmdec.c:73
static int read_header(FFV1Context *f)
Definition: ffv1dec.c:545
Stream structure.
Definition: avformat.h:876
static int read_packet(void *opaque, uint8_t *buf, int buf_size)
Definition: avio_reading.c:42
AVIOContext * pb
I/O context.
Definition: avformat.h:1393
#define GSM_BLOCK_SAMPLES
Definition: gsmdec.c:29
Describe the class of an AVClass context structure.
Definition: log.h:67
#define AVFMT_GENERIC_INDEX
Use generic index building code.
Definition: avformat.h:463
#define AV_OPT_FLAG_DECODING_PARAM
a generic parameter which can be set by the user for demuxing or decoding
Definition: opt.h:277
AVInputFormat ff_gsm_demuxer
Definition: gsmdec.c:106
#define AVPROBE_SCORE_EXTENSION
score for file extension
Definition: avformat.h:451
static int gsm_read_packet(AVFormatContext *s, AVPacket *pkt)
Definition: gsmdec.c:54
This structure contains the data a format has to probe a file.
Definition: avformat.h:441
int raw_codec_id
Raw demuxers store their codec ID here.
Definition: avformat.h:696
#define flags(name, subs,...)
Definition: cbs_av1.c:565
static int read_probe(const AVProbeData *pd)
Definition: jvdec.c:55
int sample_rate
Audio only.
Definition: codec_par.h:170
Main libavformat public API header.
static double c[64]
as in Berlin toast format
Definition: codec_id.h:428
void * priv_data
Format private data.
Definition: avformat.h:1379
int channels
Audio only.
Definition: codec_par.h:166
const char * name
A comma separated list of short names for the format.
Definition: avformat.h:650
AVCodecParameters * codecpar
Codec parameters associated with this stream.
Definition: avformat.h:1023
int stream_index
Definition: packet.h:357
#define AV_CH_LAYOUT_MONO
This structure stores compressed data.
Definition: packet.h:332
int64_t pts
Presentation timestamp in AVStream->time_base units; the time at which the decompressed packet will b...
Definition: packet.h:348