FFmpeg: libavformat/amr.c Source File

FFmpeg
amr.c
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1 /*
2  * amr file format
3  * Copyright (c) 2001 ffmpeg project
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 /*
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 
29 #include "libavutil/channel_layout.h"
30 #include "avformat.h"
31 #include "internal.h"
32 
33 typedef struct {
34   uint64_t cumulated_size;
35   uint64_t block_count;
36 } AMRContext;
37 
38  static const char AMR_header[] = "#!AMR\n";
39  static const char AMRWB_header[] = "#!AMR-WB\n";
40 
41 #if CONFIG_AMR_MUXER
42 static int amr_write_header(AVFormatContext *s)
43 {
44  AVIOContext *pb = s->pb;
45  AVCodecContext *enc = s->streams[0]->codec;
46 
47  s->priv_data = NULL;
48 
49  if (enc->codec_id == AV_CODEC_ID_AMR_NB) {
50  avio_write(pb, AMR_header, sizeof(AMR_header) - 1); /* magic number */
51  } else if (enc->codec_id == AV_CODEC_ID_AMR_WB) {
52  avio_write(pb, AMRWB_header, sizeof(AMRWB_header) - 1); /* magic number */
53  } else {
54  return -1;
55  }
56  avio_flush(pb);
57  return 0;
58 }
59 
60 static int amr_write_packet(AVFormatContext *s, AVPacket *pkt)
61 {
62  avio_write(s->pb, pkt->data, pkt->size);
63  return 0;
64 }
65 #endif /* CONFIG_AMR_MUXER */
66 
67  static int amr_probe(AVProbeData *p)
68 {
69  // Only check for "#!AMR" which could be amr-wb, amr-nb.
70  // This will also trigger multichannel files: "#!AMR_MC1.0\n" and
71  // "#!AMR-WB_MC1.0\n" (not supported)
72 
73  if (!memcmp(p->buf, AMR_header, 5))
74  return AVPROBE_SCORE_MAX;
75  else
76  return 0;
77 }
78 
79 /* amr input */
80  static int amr_read_header(AVFormatContext *s)
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  return AVERROR(ENOMEM);
91  if (memcmp(header, AMR_header, 6)) {
92  avio_read(pb, header + 6, 3);
93  if (memcmp(header, AMRWB_header, 9)) {
94  return -1;
95  }
96 
97  st->codec->codec_tag = MKTAG('s', 'a', 'w', 'b');
98  st->codec->codec_id = AV_CODEC_ID_AMR_WB;
99  st->codec->sample_rate = 16000;
100  } else {
101  st->codec->codec_tag = MKTAG('s', 'a', 'm', 'r');
102  st->codec->codec_id = AV_CODEC_ID_AMR_NB;
103  st->codec->sample_rate = 8000;
104  }
105  st->codec->channels = 1;
106  st->codec->channel_layout = AV_CH_LAYOUT_MONO;
107  st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
108  avpriv_set_pts_info(st, 64, 1, st->codec->sample_rate);
109 
110  return 0;
111 }
112 
113  static int amr_read_packet(AVFormatContext *s, AVPacket *pkt)
114 {
115  AVCodecContext *enc = s->streams[0]->codec;
116  int read, size = 0, toc, mode;
117  int64_t pos = avio_tell(s->pb);
118  AMRContext *amr = s->priv_data;
119 
120  if (avio_feof(s->pb)) {
121  return AVERROR(EIO);
122  }
123 
124  // FIXME this is wrong, this should rather be in a AVParser
125  toc = avio_r8(s->pb);
126  mode = (toc >> 3) & 0x0F;
127 
128  if (enc->codec_id == AV_CODEC_ID_AMR_NB) {
129  static const uint8_t packed_size[16] = {
130  12, 13, 15, 17, 19, 20, 26, 31, 5, 0, 0, 0, 0, 0, 0, 0
131  };
132 
133  size = packed_size[mode] + 1;
134  } else if (enc->codec_id == AV_CODEC_ID_AMR_WB) {
135  static const uint8_t packed_size[16] = {
136  18, 24, 33, 37, 41, 47, 51, 59, 61, 6, 6, 0, 0, 0, 1, 1
137  };
138 
139  size = packed_size[mode];
140  }
141 
142  if (!size || av_new_packet(pkt, size))
143  return AVERROR(EIO);
144 
145  if (amr->cumulated_size < UINT64_MAX - size) {
146  amr->cumulated_size += size;
147  /* Both AMR formats have 50 frames per second */
148  s->streams[0]->codec->bit_rate = amr->cumulated_size / ++amr->block_count * 8 * 50;
149  }
150 
151  pkt->stream_index = 0;
152  pkt->pos = pos;
153  pkt->data[0] = toc;
154  pkt->duration = enc->codec_id == AV_CODEC_ID_AMR_NB ? 160 : 320;
155  read = avio_read(s->pb, pkt->data + 1, size - 1);
156 
157  if (read != size - 1) {
158  av_free_packet(pkt);
159  return AVERROR(EIO);
160  }
161 
162  return 0;
163 }
164 
165 #if CONFIG_AMR_DEMUXER
166 AVInputFormat ff_amr_demuxer = {
167  .name = "amr",
168  .long_name = NULL_IF_CONFIG_SMALL("3GPP AMR"),
169  .priv_data_size = sizeof(AMRContext),
170  .read_probe = amr_probe,
171  .read_header = amr_read_header,
172  .read_packet = amr_read_packet,
173  .flags = AVFMT_GENERIC_INDEX,
174 };
175 #endif
176 
177 #if CONFIG_AMR_MUXER
178 AVOutputFormat ff_amr_muxer = {
179  .name = "amr",
180  .long_name = NULL_IF_CONFIG_SMALL("3GPP AMR"),
181  .mime_type = "audio/amr",
182  .extensions = "amr",
183  .audio_codec = AV_CODEC_ID_AMR_NB,
184  .video_codec = AV_CODEC_ID_NONE,
185  .write_header = amr_write_header,
186  .write_packet = amr_write_packet,
187  .flags = AVFMT_NOTIMESTAMPS,
188 };
189 #endif
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