Libav
amr.c
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1 /*
2  * amr file format
3  * Copyright (c) 2001 ffmpeg project
4  *
5  * This file is part of Libav.
6  *
7  * Libav 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  * Libav 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 Libav; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
22 /*
23 Write and read amr data according to RFC3267, http://www.ietf.org/rfc/rfc3267.txt?number=3267
24 
25 Only mono files are supported.
26 
27 */
28 
30 #include "avformat.h"
31 #include "internal.h"
32 
33 static const char AMR_header[] = "#!AMR\n";
34 static const char AMRWB_header[] = "#!AMR-WB\n";
35 
36 #if CONFIG_AMR_MUXER
37 static int amr_write_header(AVFormatContext *s)
38 {
39  AVIOContext *pb = s->pb;
40  AVCodecContext *enc = s->streams[0]->codec;
41 
42  s->priv_data = NULL;
43 
44  if (enc->codec_id == AV_CODEC_ID_AMR_NB) {
45  avio_write(pb, AMR_header, sizeof(AMR_header) - 1); /* magic number */
46  } else if (enc->codec_id == AV_CODEC_ID_AMR_WB) {
47  avio_write(pb, AMRWB_header, sizeof(AMRWB_header) - 1); /* magic number */
48  } else {
49  return -1;
50  }
51  avio_flush(pb);
52  return 0;
53 }
54 
55 static int amr_write_packet(AVFormatContext *s, AVPacket *pkt)
56 {
57  avio_write(s->pb, pkt->data, pkt->size);
58  return 0;
59 }
60 #endif /* CONFIG_AMR_MUXER */
61 
62 static int amr_probe(AVProbeData *p)
63 {
64  // Only check for "#!AMR" which could be amr-wb, amr-nb.
65  // This will also trigger multichannel files: "#!AMR_MC1.0\n" and
66  // "#!AMR-WB_MC1.0\n" (not supported)
67 
68  if (!memcmp(p->buf, AMR_header, 5))
69  return AVPROBE_SCORE_MAX;
70  else
71  return 0;
72 }
73 
74 /* amr input */
76 {
77  AVIOContext *pb = s->pb;
78  AVStream *st;
79  uint8_t header[9];
80 
81  avio_read(pb, header, 6);
82 
83  st = avformat_new_stream(s, NULL);
84  if (!st)
85  return AVERROR(ENOMEM);
86  if (memcmp(header, AMR_header, 6)) {
87  avio_read(pb, header + 6, 3);
88  if (memcmp(header, AMRWB_header, 9)) {
89  return -1;
90  }
91 
92  st->codec->codec_tag = MKTAG('s', 'a', 'w', 'b');
94  st->codec->sample_rate = 16000;
95  } else {
96  st->codec->codec_tag = MKTAG('s', 'a', 'm', 'r');
98  st->codec->sample_rate = 8000;
99  }
100  st->codec->channels = 1;
103  avpriv_set_pts_info(st, 64, 1, st->codec->sample_rate);
104 
105  return 0;
106 }
107 
109 {
110  AVCodecContext *enc = s->streams[0]->codec;
111  int read, size = 0, toc, mode;
112  int64_t pos = avio_tell(s->pb);
113 
114  if (s->pb->eof_reached) {
115  return AVERROR(EIO);
116  }
117 
118  // FIXME this is wrong, this should rather be in a AVParset
119  toc = avio_r8(s->pb);
120  mode = (toc >> 3) & 0x0F;
121 
122  if (enc->codec_id == AV_CODEC_ID_AMR_NB) {
123  static const uint8_t packed_size[16] = {
124  12, 13, 15, 17, 19, 20, 26, 31, 5, 0, 0, 0, 0, 0, 0, 0
125  };
126 
127  size = packed_size[mode] + 1;
128  } else if (enc->codec_id == AV_CODEC_ID_AMR_WB) {
129  static const uint8_t packed_size[16] = {
130  18, 24, 33, 37, 41, 47, 51, 59, 61, 6, 6, 0, 0, 0, 1, 1
131  };
132 
133  size = packed_size[mode];
134  } else {
135  assert(0);
136  }
137 
138  if (!size || av_new_packet(pkt, size))
139  return AVERROR(EIO);
140 
141  /* Both AMR formats have 50 frames per second */
142  s->streams[0]->codec->bit_rate = size*8*50;
143 
144  pkt->stream_index = 0;
145  pkt->pos = pos;
146  pkt->data[0] = toc;
147  pkt->duration = enc->codec_id == AV_CODEC_ID_AMR_NB ? 160 : 320;
148  read = avio_read(s->pb, pkt->data + 1, size - 1);
149 
150  if (read != size - 1) {
151  av_free_packet(pkt);
152  return AVERROR(EIO);
153  }
154 
155  return 0;
156 }
157 
158 #if CONFIG_AMR_DEMUXER
159 AVInputFormat ff_amr_demuxer = {
160  .name = "amr",
161  .long_name = NULL_IF_CONFIG_SMALL("3GPP AMR"),
162  .read_probe = amr_probe,
163  .read_header = amr_read_header,
164  .read_packet = amr_read_packet,
165  .flags = AVFMT_GENERIC_INDEX,
166 };
167 #endif
168 
169 #if CONFIG_AMR_MUXER
170 AVOutputFormat ff_amr_muxer = {
171  .name = "amr",
172  .long_name = NULL_IF_CONFIG_SMALL("3GPP AMR"),
173  .mime_type = "audio/amr",
174  .extensions = "amr",
175  .audio_codec = AV_CODEC_ID_AMR_NB,
176  .video_codec = AV_CODEC_ID_NONE,
177  .write_header = amr_write_header,
178  .write_packet = amr_write_packet,
179  .flags = AVFMT_NOTIMESTAMPS,
180 };
181 #endif
Bytestream IO Context.
Definition: avio.h:68
int size
void av_free_packet(AVPacket *pkt)
Free a packet.
Definition: avpacket.c:243
int64_t pos
byte position in stream, -1 if unknown
Definition: avcodec.h:992
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:2800
static int amr_read_header(AVFormatContext *s)
Definition: amr.c:75
int size
Definition: avcodec.h:968
static const char AMR_header[]
Definition: amr.c:33
Format I/O context.
Definition: avformat.h:922
uint8_t
AVStream * avformat_new_stream(AVFormatContext *s, const AVCodec *c)
Add a new stream to a media file.
Definition: utils.c:2497
AVStream ** streams
A list of all streams in the file.
Definition: avformat.h:990
uint8_t * data
Definition: avcodec.h:967
static const char AMRWB_header[]
Definition: amr.c:34
static av_always_inline int64_t avio_tell(AVIOContext *s)
ftell() equivalent for AVIOContext.
Definition: avio.h:219
void avio_write(AVIOContext *s, const unsigned char *buf, int size)
Definition: aviobuf.c:165
int duration
Duration of this packet in AVStream->time_base units, 0 if unknown.
Definition: avcodec.h:985
int avio_read(AVIOContext *s, unsigned char *buf, int size)
Read size bytes from AVIOContext into buf.
Definition: aviobuf.c:452
int av_new_packet(AVPacket *pkt, int size)
Allocate the payload of a packet and initialize its fields with default values.
Definition: avpacket.c:81
#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:150
static int amr_probe(AVProbeData *p)
Definition: amr.c:62
uint64_t channel_layout
Audio channel layout.
Definition: avcodec.h:1846
int avio_r8(AVIOContext *s)
Definition: aviobuf.c:443
AVCodecContext * codec
Codec context associated with this stream.
Definition: avformat.h:718
unsigned char * buf
Buffer must have AVPROBE_PADDING_SIZE of extra allocated bytes filled with zero.
Definition: avformat.h:397
int bit_rate
the average bitrate
Definition: avcodec.h:1108
int void avio_flush(AVIOContext *s)
Definition: aviobuf.c:180
audio channel layout utility functions
const char * name
Definition: avformat.h:446
Stream structure.
Definition: avformat.h:699
#define AVFMT_NOTIMESTAMPS
Format does not need / have any timestamps.
Definition: avformat.h:416
NULL
Definition: eval.c:55
enum AVMediaType codec_type
Definition: avcodec.h:1052
enum AVCodecID codec_id
Definition: avcodec.h:1061
int sample_rate
samples per second
Definition: avcodec.h:1785
AVIOContext * pb
I/O context.
Definition: avformat.h:964
main external API structure.
Definition: avcodec.h:1044
unsigned int codec_tag
fourcc (LSB first, so "ABCD" -> ('D'<<24) + ('C'<<16) + ('B'<<8) + 'A').
Definition: avcodec.h:1076
#define AVFMT_GENERIC_INDEX
Use generic index building code.
Definition: avformat.h:417
This structure contains the data a format has to probe a file.
Definition: avformat.h:395
static int amr_read_packet(AVFormatContext *s, AVPacket *pkt)
Definition: amr.c:108
#define AVPROBE_SCORE_MAX
maximum score
Definition: avformat.h:404
Main libavformat public API header.
int eof_reached
true if eof reached
Definition: avio.h:96
int channels
number of audio channels
Definition: avcodec.h:1786
void * priv_data
Format private data.
Definition: avformat.h:950
const char * name
A comma separated list of short names for the format.
Definition: avformat.h:525
int stream_index
Definition: avcodec.h:969
#define AV_CH_LAYOUT_MONO
#define MKTAG(a, b, c, d)
Definition: common.h:238
This structure stores compressed data.
Definition: avcodec.h:944