FFmpeg
gsmdec.c
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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  av_packet_unref(pkt);
66  return ret < 0 ? ret : AVERROR(EIO);
67  }
68  pkt->duration = 1;
69  pkt->pts = pkt->pos / GSM_BLOCK_SIZE;
70 
71  return 0;
72 }
73 
75 {
78  if (!st)
79  return AVERROR(ENOMEM);
80 
83  st->codecpar->channels = 1;
87 
89 
90  return 0;
91 }
92 
93 static const AVOption options[] = {
94  { "sample_rate", "", offsetof(GSMDemuxerContext, sample_rate),
95  AV_OPT_TYPE_INT, {.i64 = GSM_SAMPLE_RATE}, 1, INT_MAX / GSM_BLOCK_SIZE,
97  { NULL },
98 };
99 
100 static const AVClass gsm_class = {
101  .class_name = "gsm demuxer",
102  .item_name = av_default_item_name,
103  .option = options,
104  .version = LIBAVUTIL_VERSION_INT,
105 };
106 
108  .name = "gsm",
109  .long_name = NULL_IF_CONFIG_SMALL("raw GSM"),
110  .priv_data_size = sizeof(GSMDemuxerContext),
115  .extensions = "gsm",
116  .raw_codec_id = AV_CODEC_ID_GSM,
117  .priv_class = &gsm_class,
118 };
#define NULL
Definition: coverity.c:32
AVOption.
Definition: opt.h:246
#define LIBAVUTIL_VERSION_INT
Definition: version.h:85
int64_t pos
byte position in stream, -1 if unknown
Definition: avcodec.h:1500
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:4929
enum AVCodecID codec_id
Specific type of the encoded data (the codec used).
Definition: avcodec.h:3968
static const AVOption options[]
Definition: gsmdec.c:93
const char * av_default_item_name(void *ptr)
Return the context name.
Definition: log.c:191
static AVPacket pkt
Format I/O context.
Definition: avformat.h:1358
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.
Undefined Behavior In the C some operations are like signed integer dereferencing freed accessing outside allocated Undefined Behavior must not occur in a C it is not safe even if the output of undefined operations is unused The unsafety may seem nit picking but Optimizing compilers have in fact optimized code on the assumption that no undefined Behavior occurs Optimizing code based on wrong assumptions can and has in some cases lead to effects beyond the output of computations The signed integer overflow problem in speed critical code Code which is highly optimized and works with signed integers sometimes has the problem that often the output of the computation does not c
Definition: undefined.txt:32
int64_t duration
Duration of this packet in AVStream->time_base units, 0 if unknown.
Definition: avcodec.h:1498
#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:4502
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:310
ptrdiff_t size
Definition: opengl_enc.c:100
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: avcodec.h:4070
int64_t bit_rate
The average bitrate of the encoded data (in bits per second).
Definition: avcodec.h:3997
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:186
ff_const59 struct AVInputFormat * iformat
The input container format.
Definition: avformat.h:1370
static const AVClass gsm_class
Definition: gsmdec.c:100
enum AVMediaType codec_type
General type of the encoded data.
Definition: avcodec.h:3964
static int gsm_probe(const AVProbeData *p)
Definition: gsmdec.c:37
int buf_size
Size of buf except extra allocated bytes.
Definition: avformat.h:449
unsigned char * buf
Buffer must have AVPROBE_PADDING_SIZE of extra allocated bytes filled with zero.
Definition: avformat.h:448
#define b
Definition: input.c:41
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:74
static int read_header(FFV1Context *f)
Definition: ffv1dec.c:530
Stream structure.
Definition: avformat.h:881
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:1400
void av_packet_unref(AVPacket *pkt)
Wipe the packet.
Definition: avpacket.c:599
#define GSM_BLOCK_SAMPLES
Definition: gsmdec.c:29
void * buf
Definition: avisynth_c.h:766
Describe the class of an AVClass context structure.
Definition: log.h:67
#define AVFMT_GENERIC_INDEX
Use generic index building code.
Definition: avformat.h:468
#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:107
#define AVPROBE_SCORE_EXTENSION
score for file extension
Definition: avformat.h:456
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:446
int raw_codec_id
Raw demuxers store their codec ID here.
Definition: avformat.h:700
#define flags(name, subs,...)
Definition: cbs_av1.c:561
static int read_probe(const AVProbeData *pd)
Definition: jvdec.c:55
int sample_rate
Audio only.
Definition: avcodec.h:4078
Main libavformat public API header.
as in Berlin toast format
Definition: avcodec.h:583
void * priv_data
Format private data.
Definition: avformat.h:1386
int channels
Audio only.
Definition: avcodec.h:4074
const char * name
A comma separated list of short names for the format.
Definition: avformat.h:654
AVCodecParameters * codecpar
Codec parameters associated with this stream.
Definition: avformat.h:1028
int stream_index
Definition: avcodec.h:1482
Filter the word “frame” indicates either a video frame or a group of audio as stored in an AVFrame 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.Frame references ownership and permissions
#define AV_CH_LAYOUT_MONO
This structure stores compressed data.
Definition: avcodec.h:1457
int64_t pts
Presentation timestamp in AVStream->time_base units; the time at which the decompressed packet will b...
Definition: avcodec.h:1473