Libav
mp3enc.c
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1 /*
2  * MP3 muxer
3  * Copyright (c) 2003 Fabrice Bellard
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 #include "avformat.h"
23 #include "avio_internal.h"
24 #include "id3v1.h"
25 #include "id3v2.h"
26 #include "rawenc.h"
27 #include "libavutil/avstring.h"
28 #include "libavcodec/mpegaudio.h"
31 #include "libavutil/intreadwrite.h"
32 #include "libavutil/opt.h"
33 #include "libavutil/dict.h"
34 #include "libavutil/avassert.h"
35 
36 static int id3v1_set_string(AVFormatContext *s, const char *key,
37  uint8_t *buf, int buf_size)
38 {
40  if ((tag = av_dict_get(s->metadata, key, NULL, 0)))
41  av_strlcpy(buf, tag->value, buf_size);
42  return !!tag;
43 }
44 
46 {
48  int i, count = 0;
49 
50  memset(buf, 0, ID3v1_TAG_SIZE); /* fail safe */
51  buf[0] = 'T';
52  buf[1] = 'A';
53  buf[2] = 'G';
54  count += id3v1_set_string(s, "TIT2", buf + 3, 30); //title
55  count += id3v1_set_string(s, "TPE1", buf + 33, 30); //author|artist
56  count += id3v1_set_string(s, "TALB", buf + 63, 30); //album
57  count += id3v1_set_string(s, "TDRL", buf + 93, 4); //date
58  count += id3v1_set_string(s, "comment", buf + 97, 30);
59  if ((tag = av_dict_get(s->metadata, "TRCK", NULL, 0))) { //track
60  buf[125] = 0;
61  buf[126] = atoi(tag->value);
62  count++;
63  }
64  buf[127] = 0xFF; /* default to unknown genre */
65  if ((tag = av_dict_get(s->metadata, "TCON", NULL, 0))) { //genre
66  for(i = 0; i <= ID3v1_GENRE_MAX; i++) {
67  if (!av_strcasecmp(tag->value, ff_id3v1_genre_str[i])) {
68  buf[127] = i;
69  count++;
70  break;
71  }
72  }
73  }
74  return count;
75 }
76 
77 #define XING_NUM_BAGS 400
78 #define XING_TOC_SIZE 100
79 // maximum size of the xing frame: offset/Xing/flags/frames/size/TOC
80 #define XING_MAX_SIZE (32 + 4 + 4 + 4 + 4 + XING_TOC_SIZE)
81 
82 typedef struct MP3Context {
83  const AVClass *class;
88 
89  /* xing header */
90  int64_t xing_offset;
93  uint32_t want;
94  uint32_t seen;
95  uint32_t pos;
96  uint64_t bag[XING_NUM_BAGS];
99 
100  /* index of the audio stream */
102  /* number of attached pictures we still need to write */
104 
105  /* audio packets are queued here until we get all the attached pictures */
107 } MP3Context;
108 
109 static const uint8_t xing_offtbl[2][2] = {{32, 17}, {17, 9}};
110 
111 /*
112  * Write an empty XING header and initialize respective data.
113  */
115 {
116  MP3Context *mp3 = s->priv_data;
117  AVCodecContext *codec = s->streams[mp3->audio_stream_idx]->codec;
118  int32_t header;
119  MPADecodeHeader mpah;
120  int srate_idx, i, channels;
121  int bitrate_idx;
122  int best_bitrate_idx;
123  int best_bitrate_error = INT_MAX;
124  int xing_offset;
125  int ver = 0;
126  int lsf, bytes_needed;
127 
128  if (!s->pb->seekable || !mp3->write_xing)
129  return;
130 
131  for (i = 0; i < FF_ARRAY_ELEMS(avpriv_mpa_freq_tab); i++) {
132  const uint16_t base_freq = avpriv_mpa_freq_tab[i];
133 
134  if (codec->sample_rate == base_freq) ver = 0x3; // MPEG 1
135  else if (codec->sample_rate == base_freq / 2) ver = 0x2; // MPEG 2
136  else if (codec->sample_rate == base_freq / 4) ver = 0x0; // MPEG 2.5
137  else continue;
138 
139  srate_idx = i;
140  break;
141  }
143  av_log(s, AV_LOG_WARNING, "Unsupported sample rate, not writing Xing "
144  "header.\n");
145  return;
146  }
147 
148  switch (codec->channels) {
149  case 1: channels = MPA_MONO; break;
150  case 2: channels = MPA_STEREO; break;
151  default: av_log(s, AV_LOG_WARNING, "Unsupported number of channels, "
152  "not writing Xing header.\n");
153  return;
154  }
155 
156  /* dummy MPEG audio header */
157  header = 0xff << 24; // sync
158  header |= (0x7 << 5 | ver << 3 | 0x1 << 1 | 0x1) << 16; // sync/audio-version/layer 3/no crc*/
159  header |= (srate_idx << 2) << 8;
160  header |= channels << 6;
161 
162  lsf = !((header & (1 << 20) && header & (1 << 19)));
163 
164  xing_offset = xing_offtbl[ver != 3][channels == 1];
165  bytes_needed = 4 // header
166  + xing_offset
167  + 4 // xing tag
168  + 4 // frames/size/toc flags
169  + 4 // frames
170  + 4 // size
171  + XING_TOC_SIZE; // toc
172 
173  for (bitrate_idx = 1; bitrate_idx < 15; bitrate_idx++) {
174  int bit_rate = 1000 * avpriv_mpa_bitrate_tab[lsf][3 - 1][bitrate_idx];
175  int error = FFABS(bit_rate - codec->bit_rate);
176 
177  if (error < best_bitrate_error){
178  best_bitrate_error = error;
179  best_bitrate_idx = bitrate_idx;
180  }
181  }
182 
183  for (bitrate_idx = best_bitrate_idx; bitrate_idx < 15; bitrate_idx++) {
184  int32_t mask = bitrate_idx << (4 + 8);
185  header |= mask;
186 
187  avpriv_mpegaudio_decode_header(&mpah, header);
188 
189  if (bytes_needed <= mpah.frame_size)
190  break;
191 
192  header &= ~mask;
193  }
194 
195  avio_wb32(s->pb, header);
196 
197  avpriv_mpegaudio_decode_header(&mpah, header);
198 
199  av_assert0(mpah.frame_size >= XING_MAX_SIZE);
200 
201  ffio_fill(s->pb, 0, xing_offset);
202  mp3->xing_offset = avio_tell(s->pb);
203  ffio_wfourcc(s->pb, "Xing");
204  avio_wb32(s->pb, 0x01 | 0x02 | 0x04); // frames / size / TOC
205 
206  mp3->size = mpah.frame_size;
207  mp3->want = 1;
208 
209  avio_wb32(s->pb, 0); // frames
210  avio_wb32(s->pb, 0); // size
211 
212  // TOC
213  for (i = 0; i < XING_TOC_SIZE; i++)
214  avio_w8(s->pb, 255 * i / XING_TOC_SIZE);
215 
216  ffio_fill(s->pb, 0, mpah.frame_size - bytes_needed);
217 }
218 
219 /*
220  * Add a frame to XING data.
221  * Following lame's "VbrTag.c".
222  */
223 static void mp3_xing_add_frame(MP3Context *mp3, AVPacket *pkt)
224 {
225  int i;
226 
227  mp3->frames++;
228  mp3->seen++;
229  mp3->size += pkt->size;
230 
231  if (mp3->want == mp3->seen) {
232  mp3->bag[mp3->pos] = mp3->size;
233 
234  if (XING_NUM_BAGS == ++mp3->pos) {
235  /* shrink table to half size by throwing away each second bag. */
236  for (i = 1; i < XING_NUM_BAGS; i += 2)
237  mp3->bag[i / 2] = mp3->bag[i];
238 
239  /* double wanted amount per bag. */
240  mp3->want *= 2;
241  /* adjust current position to half of table size. */
242  mp3->pos = XING_NUM_BAGS / 2;
243  }
244 
245  mp3->seen = 0;
246  }
247 }
248 
250 {
251  MP3Context *mp3 = s->priv_data;
252 
253  if (mp3->xing_offset && pkt->size >= 4) {
254  MPADecodeHeader c;
255 
257 
258  if (!mp3->initial_bitrate)
259  mp3->initial_bitrate = c.bit_rate;
260  if ((c.bit_rate == 0) || (mp3->initial_bitrate != c.bit_rate))
261  mp3->has_variable_bitrate = 1;
262 
263  mp3_xing_add_frame(mp3, pkt);
264  }
265 
266  return ff_raw_write_packet(s, pkt);
267 }
268 
270 {
271  MP3Context *mp3 = s->priv_data;
272  AVPacketList *pktl;
273  int ret = 0, write = 1;
274 
275  ff_id3v2_finish(&mp3->id3, s->pb);
276  mp3_write_xing(s);
277 
278  while ((pktl = mp3->queue)) {
279  if (write && (ret = mp3_write_audio_packet(s, &pktl->pkt)) < 0)
280  write = 0;
281  av_free_packet(&pktl->pkt);
282  mp3->queue = pktl->next;
283  av_freep(&pktl);
284  }
285  mp3->queue_end = NULL;
286  return ret;
287 }
288 
290 {
291  MP3Context *mp3 = s->priv_data;
292  int i;
293 
294  /* replace "Xing" identification string with "Info" for CBR files. */
295  if (!mp3->has_variable_bitrate) {
296  avio_seek(s->pb, mp3->xing_offset, SEEK_SET);
297  ffio_wfourcc(s->pb, "Info");
298  }
299 
300  avio_seek(s->pb, mp3->xing_offset + 8, SEEK_SET);
301  avio_wb32(s->pb, mp3->frames);
302  avio_wb32(s->pb, mp3->size);
303 
304  avio_w8(s->pb, 0); // first toc entry has to be zero.
305 
306  for (i = 1; i < XING_TOC_SIZE; ++i) {
307  int j = i * mp3->pos / XING_TOC_SIZE;
308  int seek_point = 256LL * mp3->bag[j] / mp3->size;
309  avio_w8(s->pb, FFMIN(seek_point, 255));
310  }
311 
312  avio_seek(s->pb, 0, SEEK_END);
313 }
314 
315 static int mp3_write_trailer(struct AVFormatContext *s)
316 {
317  uint8_t buf[ID3v1_TAG_SIZE];
318  MP3Context *mp3 = s->priv_data;
319 
320  if (mp3->pics_to_write) {
321  av_log(s, AV_LOG_WARNING, "No packets were sent for some of the "
322  "attached pictures.\n");
323  mp3_queue_flush(s);
324  }
325 
326  /* write the id3v1 tag */
327  if (mp3->write_id3v1 && id3v1_create_tag(s, buf) > 0) {
328  avio_write(s->pb, buf, ID3v1_TAG_SIZE);
329  }
330 
331  if (mp3->xing_offset)
332  mp3_update_xing(s);
333 
334  return 0;
335 }
336 
337 #if CONFIG_MP2_MUXER
338 AVOutputFormat ff_mp2_muxer = {
339  .name = "mp2",
340  .long_name = NULL_IF_CONFIG_SMALL("MP2 (MPEG audio layer 2)"),
341  .mime_type = "audio/x-mpeg",
342  .extensions = "mp2,m2a,mpa",
343  .audio_codec = AV_CODEC_ID_MP2,
344  .video_codec = AV_CODEC_ID_NONE,
345  .write_packet = ff_raw_write_packet,
346  .flags = AVFMT_NOTIMESTAMPS,
347 };
348 #endif
349 
350 #if CONFIG_MP3_MUXER
351 
352 static const AVOption options[] = {
353  { "id3v2_version", "Select ID3v2 version to write. Currently 3 and 4 are supported.",
354  offsetof(MP3Context, id3v2_version), AV_OPT_TYPE_INT, {.i64 = 4}, 0, 4, AV_OPT_FLAG_ENCODING_PARAM},
355  { "write_id3v1", "Enable ID3v1 writing. ID3v1 tags are written in UTF-8 which may not be supported by most software.",
356  offsetof(MP3Context, write_id3v1), AV_OPT_TYPE_INT, {.i64 = 0}, 0, 1, AV_OPT_FLAG_ENCODING_PARAM},
357  { "write_xing", "Write the Xing header containing file duration.",
358  offsetof(MP3Context, write_xing), AV_OPT_TYPE_INT, {.i64 = 1}, 0, 1, AV_OPT_FLAG_ENCODING_PARAM},
359  { NULL },
360 };
361 
362 static const AVClass mp3_muxer_class = {
363  .class_name = "MP3 muxer",
364  .item_name = av_default_item_name,
365  .option = options,
366  .version = LIBAVUTIL_VERSION_INT,
367 };
368 
369 static int mp3_write_packet(AVFormatContext *s, AVPacket *pkt)
370 {
371  MP3Context *mp3 = s->priv_data;
372 
373  if (pkt->stream_index == mp3->audio_stream_idx) {
374  if (mp3->pics_to_write) {
375  /* buffer audio packets until we get all the pictures */
376  AVPacketList *pktl = av_mallocz(sizeof(*pktl));
377  if (!pktl)
378  return AVERROR(ENOMEM);
379 
380  pktl->pkt = *pkt;
381  pktl->pkt.buf = av_buffer_ref(pkt->buf);
382  if (!pktl->pkt.buf) {
383  av_freep(&pktl);
384  return AVERROR(ENOMEM);
385  }
386 
387  if (mp3->queue_end)
388  mp3->queue_end->next = pktl;
389  else
390  mp3->queue = pktl;
391  mp3->queue_end = pktl;
392  } else
393  return mp3_write_audio_packet(s, pkt);
394  } else {
395  int ret;
396 
397  /* warn only once for each stream */
398  if (s->streams[pkt->stream_index]->nb_frames == 1) {
399  av_log(s, AV_LOG_WARNING, "Got more than one picture in stream %d,"
400  " ignoring.\n", pkt->stream_index);
401  }
402  if (!mp3->pics_to_write || s->streams[pkt->stream_index]->nb_frames >= 1)
403  return 0;
404 
405  if ((ret = ff_id3v2_write_apic(s, &mp3->id3, pkt)) < 0)
406  return ret;
407  mp3->pics_to_write--;
408 
409  /* flush the buffered audio packets */
410  if (!mp3->pics_to_write &&
411  (ret = mp3_queue_flush(s)) < 0)
412  return ret;
413  }
414 
415  return 0;
416 }
417 
422 static int mp3_write_header(struct AVFormatContext *s)
423 {
424  MP3Context *mp3 = s->priv_data;
425  int ret, i;
426 
427  if (mp3->id3v2_version &&
428  mp3->id3v2_version != 3 &&
429  mp3->id3v2_version != 4) {
430  av_log(s, AV_LOG_ERROR, "Invalid ID3v2 version requested: %d. Only "
431  "3, 4 or 0 (disabled) are allowed.\n", mp3->id3v2_version);
432  return AVERROR(EINVAL);
433  }
434 
435  /* check the streams -- we want exactly one audio and arbitrary number of
436  * video (attached pictures) */
437  mp3->audio_stream_idx = -1;
438  for (i = 0; i < s->nb_streams; i++) {
439  AVStream *st = s->streams[i];
440  if (st->codec->codec_type == AVMEDIA_TYPE_AUDIO) {
441  if (mp3->audio_stream_idx >= 0 || st->codec->codec_id != AV_CODEC_ID_MP3) {
442  av_log(s, AV_LOG_ERROR, "Invalid audio stream. Exactly one MP3 "
443  "audio stream is required.\n");
444  return AVERROR(EINVAL);
445  }
446  mp3->audio_stream_idx = i;
447  } else if (st->codec->codec_type != AVMEDIA_TYPE_VIDEO) {
448  av_log(s, AV_LOG_ERROR, "Only audio streams and pictures are allowed in MP3.\n");
449  return AVERROR(EINVAL);
450  }
451  }
452  if (mp3->audio_stream_idx < 0) {
453  av_log(s, AV_LOG_ERROR, "No audio stream present.\n");
454  return AVERROR(EINVAL);
455  }
456  mp3->pics_to_write = s->nb_streams - 1;
457 
458  if (mp3->pics_to_write && !mp3->id3v2_version) {
459  av_log(s, AV_LOG_ERROR, "Attached pictures were requested, but the "
460  "ID3v2 header is disabled.\n");
461  return AVERROR(EINVAL);
462  }
463 
464  if (mp3->id3v2_version) {
466  ret = ff_id3v2_write_metadata(s, &mp3->id3);
467  if (ret < 0)
468  return ret;
469  }
470 
471  if (!mp3->pics_to_write) {
472  if (mp3->id3v2_version)
473  ff_id3v2_finish(&mp3->id3, s->pb);
474  mp3_write_xing(s);
475  }
476 
477  return 0;
478 }
479 
480 AVOutputFormat ff_mp3_muxer = {
481  .name = "mp3",
482  .long_name = NULL_IF_CONFIG_SMALL("MP3 (MPEG audio layer 3)"),
483  .mime_type = "audio/x-mpeg",
484  .extensions = "mp3",
485  .priv_data_size = sizeof(MP3Context),
486  .audio_codec = AV_CODEC_ID_MP3,
487  .video_codec = AV_CODEC_ID_PNG,
488  .write_header = mp3_write_header,
489  .write_packet = mp3_write_packet,
492  .priv_class = &mp3_muxer_class,
493 };
494 #endif