FFmpeg
g726.c
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1 /*
2  * G.726 raw demuxer
3  * Copyright 2017 Carl Eugen Hoyos
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 "avformat.h"
23 #include "internal.h"
24 #include "libavutil/opt.h"
25 
26 typedef struct G726Context {
27  AVClass *class;
28  int code_size;
30 } G726Context;
31 
33 {
34  G726Context *c = s->priv_data;
36  if (!st)
37  return AVERROR(ENOMEM);
38 
41 
44  st->codecpar->bit_rate = ((int[]){ 16000, 24000, 32000, 40000 })[c->code_size - 2];
45  st->codecpar->channels = 1;
46 
47  return 0;
48 }
49 
51 {
52  int res;
53  res = av_get_packet(s->pb, pkt, 1020); // a size similar to RAW_PACKET_SIZE divisible by all code_size values
54  if (res < 0)
55  return res;
56  return 0;
57 }
58 
59 #define OFFSET(x) offsetof(G726Context, x)
60 static const AVOption options[] = {
61  { "code_size", "Bits per G.726 code",
63  { "sample_rate", "",
64  OFFSET(sample_rate), AV_OPT_TYPE_INT, {.i64 = 8000}, 0, INT_MAX, AV_OPT_FLAG_DECODING_PARAM },
65  { NULL },
66 };
67 
68 #if CONFIG_G726_DEMUXER
69 static const AVClass g726le_demuxer_class = {
70  .class_name = "G.726 big-endian demuxer",
71  .item_name = av_default_item_name,
72  .option = options,
73  .version = LIBAVUTIL_VERSION_INT,
74 };
75 
77  .name = "g726",
78  .long_name = NULL_IF_CONFIG_SMALL("raw big-endian G.726 (\"left aligned\")"),
79  .read_header = g726_read_header,
80  .read_packet = g726_read_packet,
81  .priv_data_size = sizeof(G726Context),
82  .priv_class = &g726le_demuxer_class,
83  .raw_codec_id = AV_CODEC_ID_ADPCM_G726,
84 };
85 #endif
86 
87 #if CONFIG_G726LE_DEMUXER
88 static const AVClass g726_demuxer_class = {
89  .class_name = "G.726 little-endian demuxer",
90  .item_name = av_default_item_name,
91  .option = options,
92  .version = LIBAVUTIL_VERSION_INT,
93 };
94 
96  .name = "g726le",
97  .long_name = NULL_IF_CONFIG_SMALL("raw little-endian G.726 (\"right aligned\")"),
98  .read_header = g726_read_header,
99  .read_packet = g726_read_packet,
100  .priv_data_size = sizeof(G726Context),
101  .priv_class = &g726_demuxer_class,
102  .raw_codec_id = AV_CODEC_ID_ADPCM_G726LE,
103 };
104 #endif
105 
#define NULL
Definition: coverity.c:32
AVOption.
Definition: opt.h:246
#define LIBAVUTIL_VERSION_INT
Definition: version.h:85
int sample_rate
Definition: g726.c:29
enum AVCodecID codec_id
Specific type of the encoded data (the codec used).
Definition: avcodec.h:3960
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
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
AVStream * avformat_new_stream(AVFormatContext *s, const AVCodec *c)
Add a new stream to a media file.
Definition: utils.c:4469
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
AVInputFormat ff_g726le_demuxer
int64_t bit_rate
The average bitrate of the encoded data (in bits per second).
Definition: avcodec.h:3989
AVInputFormat ff_g726_demuxer
#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
enum AVMediaType codec_type
General type of the encoded data.
Definition: avcodec.h:3956
static const AVOption options[]
Definition: g726.c:60
#define OFFSET(x)
Definition: g726.c:59
#define s(width, name)
Definition: cbs_vp9.c:257
Stream structure.
Definition: avformat.h:881
static int g726_read_header(AVFormatContext *s)
Definition: g726.c:32
AVIOContext * pb
I/O context.
Definition: avformat.h:1400
Describe the class of an AVClass context structure.
Definition: log.h:67
#define AV_OPT_FLAG_DECODING_PARAM
a generic parameter which can be set by the user for demuxing or decoding
Definition: opt.h:277
int raw_codec_id
Raw demuxers store their codec ID here.
Definition: avformat.h:700
int code_size
Definition: g726.c:97
int sample_rate
Audio only.
Definition: avcodec.h:4070
Main libavformat public API header.
void * priv_data
Format private data.
Definition: avformat.h:1386
int bits_per_coded_sample
The number of bits per sample in the codedwords.
Definition: avcodec.h:4002
int channels
Audio only.
Definition: avcodec.h:4066
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
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
static int g726_read_packet(AVFormatContext *s, AVPacket *pkt)
Definition: g726.c:50
This structure stores compressed data.
Definition: avcodec.h:1457