amr.c
Go to the documentation of this file.
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 #include "avformat.h"
29 #include "internal.h"
30 
31 static const char AMR_header [] = "#!AMR\n";
32 static const char AMRWB_header [] = "#!AMR-WB\n";
33 
34 #if CONFIG_AMR_MUXER
35 static int amr_write_header(AVFormatContext *s)
36 {
37  AVIOContext *pb = s->pb;
38  AVCodecContext *enc = s->streams[0]->codec;
39 
40  s->priv_data = NULL;
41 
42  if (enc->codec_id == CODEC_ID_AMR_NB)
43  {
44  avio_write(pb, AMR_header, sizeof(AMR_header) - 1); /* magic number */
45  }
46  else if(enc->codec_id == CODEC_ID_AMR_WB)
47  {
48  avio_write(pb, AMRWB_header, sizeof(AMRWB_header) - 1); /* magic number */
49  }
50  else
51  {
52  return -1;
53  }
54  avio_flush(pb);
55  return 0;
56 }
57 
58 static int amr_write_packet(AVFormatContext *s, AVPacket *pkt)
59 {
60  avio_write(s->pb, pkt->data, pkt->size);
61  avio_flush(s->pb);
62  return 0;
63 }
64 #endif /* CONFIG_AMR_MUXER */
65 
66 static int amr_probe(AVProbeData *p)
67 {
68  //Only check for "#!AMR" which could be amr-wb, amr-nb.
69  //This will also trigger multichannel files: "#!AMR_MC1.0\n" and
70  //"#!AMR-WB_MC1.0\n" (not supported)
71 
72  if(memcmp(p->buf,AMR_header,5)==0)
73  return AVPROBE_SCORE_MAX;
74  else
75  return 0;
76 }
77 
78 /* amr input */
81 {
82  AVIOContext *pb = s->pb;
83  AVStream *st;
84  uint8_t header[9];
85 
86  avio_read(pb, header, 6);
87 
88  st = avformat_new_stream(s, NULL);
89  if (!st)
90  {
91  return AVERROR(ENOMEM);
92  }
93  if(memcmp(header,AMR_header,6)!=0)
94  {
95  avio_read(pb, header+6, 3);
96  if(memcmp(header,AMRWB_header,9)!=0)
97  {
98  return -1;
99  }
100 
101  st->codec->codec_tag = MKTAG('s', 'a', 'w', 'b');
103  st->codec->sample_rate = 16000;
104  st->codec->frame_size = 320;
105  }
106  else
107  {
108  st->codec->codec_tag = MKTAG('s', 'a', 'm', 'r');
110  st->codec->sample_rate = 8000;
111  st->codec->frame_size = 160;
112  }
113  st->codec->channels = 1;
115  avpriv_set_pts_info(st, 64, 1, st->codec->sample_rate);
116 
117  return 0;
118 }
119 
121  AVPacket *pkt)
122 {
123  AVCodecContext *enc = s->streams[0]->codec;
124  int read, size = 0, toc, mode;
125  int64_t pos = avio_tell(s->pb);
126 
127  if (s->pb->eof_reached)
128  {
129  return AVERROR(EIO);
130  }
131 
132 //FIXME this is wrong, this should rather be in a AVParset
133  toc=avio_r8(s->pb);
134  mode = (toc >> 3) & 0x0F;
135 
136  if (enc->codec_id == CODEC_ID_AMR_NB)
137  {
138  static const uint8_t packed_size[16] = {12, 13, 15, 17, 19, 20, 26, 31, 5, 0, 0, 0, 0, 0, 0, 0};
139 
140  size=packed_size[mode]+1;
141  }
142  else if(enc->codec_id == CODEC_ID_AMR_WB)
143  {
144  static uint8_t packed_size[16] = {18, 24, 33, 37, 41, 47, 51, 59, 61, 6, 6, 0, 0, 0, 1, 1};
145 
146  size=packed_size[mode];
147  }
148  else
149  {
150  assert(0);
151  }
152 
153  if ( (size==0) || av_new_packet(pkt, size))
154  {
155  return AVERROR(EIO);
156  }
157 
158  /* Both AMR formats have 50 frames per second */
159  s->streams[0]->codec->bit_rate = size*8*50;
160 
161  pkt->stream_index = 0;
162  pkt->pos = pos;
163  pkt->data[0]=toc;
164  pkt->duration= enc->codec_id == CODEC_ID_AMR_NB ? 160 : 320;
165  read = avio_read(s->pb, pkt->data+1, size-1);
166 
167  if (read != size-1)
168  {
169  av_free_packet(pkt);
170  return AVERROR(EIO);
171  }
172 
173  return 0;
174 }
175 
176 #if CONFIG_AMR_DEMUXER
177 AVInputFormat ff_amr_demuxer = {
178  .name = "amr",
179  .long_name = NULL_IF_CONFIG_SMALL("3GPP AMR file format"),
180  .read_probe = amr_probe,
181  .read_header = amr_read_header,
182  .read_packet = amr_read_packet,
183  .flags = AVFMT_GENERIC_INDEX,
184 };
185 #endif
186 
187 #if CONFIG_AMR_MUXER
188 AVOutputFormat ff_amr_muxer = {
189  .name = "amr",
190  .long_name = NULL_IF_CONFIG_SMALL("3GPP AMR file format"),
191  .mime_type = "audio/amr",
192  .extensions = "amr",
193  .audio_codec = CODEC_ID_AMR_NB,
194  .video_codec = CODEC_ID_NONE,
195  .write_header = amr_write_header,
196  .write_packet = amr_write_packet,
197 };
198 #endif
Bytestream IO Context.
Definition: avio.h:68
int size
static int amr_read_header(AVFormatContext *s, AVFormatParameters *ap)
Definition: amr.c:79
int64_t pos
byte position in stream, -1 if unknown
Definition: avcodec.h:933
void avpriv_set_pts_info(AVStream *s, int pts_wrap_bits, unsigned int pts_num, unsigned int pts_den)
Set the pts for a given stream.
Definition: utils.c:3828
int av_new_packet(AVPacket *pkt, int size)
Allocate the payload of a packet and initialize its fields with default values.
Definition: avpacket.c:60
int size
Definition: avcodec.h:909
static const char AMR_header[]
Definition: amr.c:31
Format I/O context.
Definition: avformat.h:863
AVStream ** streams
Definition: avformat.h:908
uint8_t * data
Definition: avcodec.h:908
static const char AMRWB_header[]
Definition: amr.c:32
void av_free_packet(AVPacket *pkt)
Free a packet.
Definition: avpacket.c:151
static av_always_inline int64_t avio_tell(AVIOContext *s)
ftell() equivalent for AVIOContext.
Definition: avio.h:492
void avio_write(AVIOContext *s, const unsigned char *buf, int size)
Definition: aviobuf.c:190
int duration
Duration of this packet in AVStream->time_base units, 0 if unknown.
Definition: avcodec.h:930
int avio_read(AVIOContext *s, unsigned char *buf, int size)
Read size bytes from AVIOContext into buf.
Definition: aviobuf.c:652
#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:191
AVStream * avformat_new_stream(AVFormatContext *s, AVCodec *c)
Add a new stream to a media file.
Definition: utils.c:2776
static int amr_probe(AVProbeData *p)
Definition: amr.c:66
int avio_r8(AVIOContext *s)
Definition: aviobuf.c:632
AVCodecContext * codec
codec context
Definition: avformat.h:623
unsigned char * buf
Buffer must have AVPROBE_PADDING_SIZE of extra allocated bytes filled with zero.
Definition: avformat.h:341
int bit_rate
the average bitrate
Definition: avcodec.h:1340
int void avio_flush(AVIOContext *s)
Definition: aviobuf.c:205
const char * name
Definition: avformat.h:390
Stream structure.
Definition: avformat.h:620
int frame_size
Samples per packet, initialized when calling 'init'.
Definition: avcodec.h:1470
NULL
Definition: eval.c:50
enum AVMediaType codec_type
Definition: avcodec.h:1574
int sample_rate
samples per second
Definition: avcodec.h:1456
AVIOContext * pb
Definition: avformat.h:896
main external API structure.
Definition: avcodec.h:1329
unsigned int codec_tag
fourcc (LSB first, so "ABCD" -> ('D'<<24) + ('C'<<16) + ('B'<<8) + 'A').
Definition: avcodec.h:1590
#define AVFMT_GENERIC_INDEX
Use generic index building code.
Definition: avformat.h:376
This structure contains the data a format has to probe a file.
Definition: avformat.h:339
static int amr_read_packet(AVFormatContext *s, AVPacket *pkt)
Definition: amr.c:120
#define AVPROBE_SCORE_MAX
maximum score, half of that is used for file-extension-based detection
Definition: avformat.h:345
Main libavformat public API header.
int eof_reached
true if eof reached
Definition: avio.h:98
int channels
number of audio channels
Definition: avcodec.h:1457
void * priv_data
Format private data.
Definition: avformat.h:883
const char * name
A comma separated list of short names for the format.
Definition: avformat.h:460
int stream_index
Definition: avcodec.h:910
#define MKTAG(a, b, c, d)
Definition: common.h:231
enum CodecID codec_id
Definition: avcodec.h:1575