FFmpeg  4.0
g726.c
Go to the documentation of this file.
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
const char * s
Definition: avisynth_c.h:768
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:3884
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:1342
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.
AVStream * avformat_new_stream(AVFormatContext *s, const AVCodec *c)
Add a new stream to a media file.
Definition: utils.c:4441
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:3913
AVInputFormat ff_g726_demuxer
#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:186
enum AVMediaType codec_type
General type of the encoded data.
Definition: avcodec.h:3880
static const AVOption options[]
Definition: g726.c:60
#define OFFSET(x)
Definition: g726.c:59
Stream structure.
Definition: avformat.h:873
static int g726_read_header(AVFormatContext *s)
Definition: g726.c:32
AVIOContext * pb
I/O context.
Definition: avformat.h:1384
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:693
int code_size
Definition: g726.c:97
int sample_rate
Audio only.
Definition: avcodec.h:3994
Main libavformat public API header.
static double c[64]
struct AVInputFormat * iformat
The input container format.
Definition: avformat.h:1354
void * priv_data
Format private data.
Definition: avformat.h:1370
int bits_per_coded_sample
The number of bits per sample in the codedwords.
Definition: avcodec.h:3926
int channels
Audio only.
Definition: avcodec.h:3990
const char * name
A comma separated list of short names for the format.
Definition: avformat.h:647
AVCodecParameters * codecpar
Codec parameters associated with this stream.
Definition: avformat.h:1020
static int g726_read_packet(AVFormatContext *s, AVPacket *pkt)
Definition: g726.c:50
This structure stores compressed data.
Definition: avcodec.h:1407