FFmpeg
mp3dec.c
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1 /*
2  * MP3 demuxer
3  * Copyright (c) 2003 Fabrice Bellard
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 "libavutil/opt.h"
23 #include "libavutil/avstring.h"
24 #include "libavutil/intreadwrite.h"
25 #include "libavutil/crc.h"
26 #include "libavutil/dict.h"
27 #include "libavutil/mathematics.h"
28 #include "avformat.h"
29 #include "internal.h"
30 #include "avio_internal.h"
31 #include "id3v2.h"
32 #include "id3v1.h"
33 #include "replaygain.h"
34 
35 #include "libavcodec/avcodec.h"
36 #include "libavcodec/mpegaudiodecheader.h"
37 
38 #define XING_FLAG_FRAMES 0x01
39 #define XING_FLAG_SIZE 0x02
40 #define XING_FLAG_TOC 0x04
41 #define XING_FLAC_QSCALE 0x08
42 
43 #define XING_TOC_COUNT 100
44 
45 
46 typedef struct {
47  AVClass *class;
48  int64_t filesize;
49  int xing_toc;
50  int start_pad;
51  int end_pad;
52  int usetoc;
53  unsigned frames; /* Total number of frames in file */
54  unsigned header_filesize; /* Total number of bytes in the stream */
55  int is_cbr;
56 } MP3DecContext;
57 
58 enum CheckRet {
59  CHECK_WRONG_HEADER = -1,
60  CHECK_SEEK_FAILED = -2,
61 };
62 
63 static int check(AVIOContext *pb, int64_t pos, uint32_t *header);
64 
65 /* mp3 read */
66 
67 static int mp3_read_probe(const AVProbeData *p)
68 {
69  int max_frames, first_frames = 0;
70  int whole_used = 0;
71  int frames, ret;
72  int framesizes, max_framesizes;
73  uint32_t header;
74  const uint8_t *buf, *buf0, *buf2, *buf3, *end;
75 
76  buf0 = p->buf;
77  end = p->buf + p->buf_size - sizeof(uint32_t);
78  while (buf0 < end && !*buf0)
79  buf0++;
80 
81  max_frames = 0;
82  max_framesizes = 0;
83  buf = buf0;
84 
85  for (; buf < end; buf = buf2+1) {
86  buf2 = buf;
87  for (framesizes = frames = 0; buf2 < end; frames++) {
88  MPADecodeHeader h;
89  int header_emu = 0;
90  int available;
91 
92  header = AV_RB32(buf2);
93  ret = avpriv_mpegaudio_decode_header(&h, header);
94  if (ret != 0)
95  break;
96 
97  available = FFMIN(h.frame_size, end - buf2);
98  for (buf3 = buf2 + 4; buf3 < buf2 + available; buf3++) {
99  uint32_t next_sync = AV_RB32(buf3);
100  header_emu += (next_sync & MP3_MASK) == (header & MP3_MASK);
101  }
102  if (header_emu > 2)
103  break;
104  framesizes += h.frame_size;
105  if (available < h.frame_size) {
106  frames++;
107  break;
108  }
109  buf2 += h.frame_size;
110  }
111  max_frames = FFMAX(max_frames, frames);
112  max_framesizes = FFMAX(max_framesizes, framesizes);
113  if (buf == buf0) {
114  first_frames= frames;
115  if (buf2 == end + sizeof(uint32_t))
116  whole_used = 1;
117  }
118  }
119  // keep this in sync with ac3 probe, both need to avoid
120  // issues with MPEG-files!
121  if (first_frames>=7) return AVPROBE_SCORE_EXTENSION + 1;
122  else if (max_frames>200 && p->buf_size < 2*max_framesizes)return AVPROBE_SCORE_EXTENSION;
123  else if (max_frames>=4 && p->buf_size < 2*max_framesizes) return AVPROBE_SCORE_EXTENSION / 2;
124  else if (ff_id3v2_match(buf0, ID3v2_DEFAULT_MAGIC) && 2*ff_id3v2_tag_len(buf0) >= p->buf_size)
125  return p->buf_size < PROBE_BUF_MAX ? AVPROBE_SCORE_EXTENSION / 4 : AVPROBE_SCORE_EXTENSION - 2;
126  else if (first_frames > 1 && whole_used) return 5;
127  else if (max_frames>=1 && p->buf_size < 10*max_framesizes) return 1;
128  else return 0;
129  //mpegps_mp3_unrecognized_format.mpg has max_frames=3
130 }
131 
132 static void read_xing_toc(AVFormatContext *s, int64_t filesize, int64_t duration)
133 {
134  int i;
135  MP3DecContext *mp3 = s->priv_data;
136  int fast_seek = s->flags & AVFMT_FLAG_FAST_SEEK;
137  int fill_index = (mp3->usetoc || fast_seek) && duration > 0;
138 
139  if (!filesize &&
140  !(filesize = avio_size(s->pb))) {
141  av_log(s, AV_LOG_WARNING, "Cannot determine file size, skipping TOC table.\n");
142  fill_index = 0;
143  }
144 
145  for (i = 0; i < XING_TOC_COUNT; i++) {
146  uint8_t b = avio_r8(s->pb);
147  if (fill_index)
148  av_add_index_entry(s->streams[0],
149  av_rescale(b, filesize, 256),
150  av_rescale(i, duration, XING_TOC_COUNT),
151  0, 0, AVINDEX_KEYFRAME);
152  }
153  if (fill_index)
154  mp3->xing_toc = 1;
155 }
156 
157 static void mp3_parse_info_tag(AVFormatContext *s, AVStream *st,
158  MPADecodeHeader *c, uint32_t spf)
159 {
160 #define LAST_BITS(k, n) ((k) & ((1 << (n)) - 1))
161 #define MIDDLE_BITS(k, m, n) LAST_BITS((k) >> (m), ((n) - (m) + 1))
162 
163  uint16_t crc;
164  uint32_t v;
165 
166  char version[10];
167 
168  uint32_t peak = 0;
169  int32_t r_gain = INT32_MIN, a_gain = INT32_MIN;
170 
171  MP3DecContext *mp3 = s->priv_data;
172  static const int64_t xing_offtbl[2][2] = {{32, 17}, {17,9}};
173  uint64_t fsize = avio_size(s->pb);
174  fsize = fsize >= avio_tell(s->pb) ? fsize - avio_tell(s->pb) : 0;
175 
176  /* Check for Xing / Info tag */
177  avio_skip(s->pb, xing_offtbl[c->lsf == 1][c->nb_channels == 1]);
178  v = avio_rb32(s->pb);
179  mp3->is_cbr = v == MKBETAG('I', 'n', 'f', 'o');
180  if (v != MKBETAG('X', 'i', 'n', 'g') && !mp3->is_cbr)
181  return;
182 
183  v = avio_rb32(s->pb);
184  if (v & XING_FLAG_FRAMES)
185  mp3->frames = avio_rb32(s->pb);
186  if (v & XING_FLAG_SIZE)
187  mp3->header_filesize = avio_rb32(s->pb);
188  if (fsize && mp3->header_filesize) {
189  uint64_t min, delta;
190  min = FFMIN(fsize, mp3->header_filesize);
191  delta = FFMAX(fsize, mp3->header_filesize) - min;
192  if (fsize > mp3->header_filesize && delta > min >> 4) {
193  mp3->frames = 0;
194  av_log(s, AV_LOG_WARNING,
195  "invalid concatenated file detected - using bitrate for duration\n");
196  } else if (delta > min >> 4) {
197  av_log(s, AV_LOG_WARNING,
198  "filesize and duration do not match (growing file?)\n");
199  }
200  }
201  if (v & XING_FLAG_TOC)
202  read_xing_toc(s, mp3->header_filesize, av_rescale_q(mp3->frames,
203  (AVRational){spf, c->sample_rate},
204  st->time_base));
205  /* VBR quality */
206  if (v & XING_FLAC_QSCALE)
207  avio_rb32(s->pb);
208 
209  /* Encoder short version string */
210  memset(version, 0, sizeof(version));
211  avio_read(s->pb, version, 9);
212 
213  /* Info Tag revision + VBR method */
214  avio_r8(s->pb);
215 
216  /* Lowpass filter value */
217  avio_r8(s->pb);
218 
219  /* ReplayGain peak */
220  v = avio_rb32(s->pb);
221  peak = av_rescale(v, 100000, 1 << 23);
222 
223  /* Radio ReplayGain */
224  v = avio_rb16(s->pb);
225 
226  if (MIDDLE_BITS(v, 13, 15) == 1) {
227  r_gain = MIDDLE_BITS(v, 0, 8) * 10000;
228 
229  if (v & (1 << 9))
230  r_gain *= -1;
231  }
232 
233  /* Audiophile ReplayGain */
234  v = avio_rb16(s->pb);
235 
236  if (MIDDLE_BITS(v, 13, 15) == 2) {
237  a_gain = MIDDLE_BITS(v, 0, 8) * 10000;
238 
239  if (v & (1 << 9))
240  a_gain *= -1;
241  }
242 
243  /* Encoding flags + ATH Type */
244  avio_r8(s->pb);
245 
246  /* if ABR {specified bitrate} else {minimal bitrate} */
247  avio_r8(s->pb);
248 
249  /* Encoder delays */
250  v = avio_rb24(s->pb);
251  if (AV_RB32(version) == MKBETAG('L', 'A', 'M', 'E')
252  || AV_RB32(version) == MKBETAG('L', 'a', 'v', 'f')
253  || AV_RB32(version) == MKBETAG('L', 'a', 'v', 'c')
254  ) {
255 
256  mp3->start_pad = v>>12;
257  mp3-> end_pad = v&4095;
258  st->internal->start_skip_samples = mp3->start_pad + 528 + 1;
259  if (mp3->frames) {
260  st->internal->first_discard_sample = -mp3->end_pad + 528 + 1 + mp3->frames * (int64_t)spf;
261  st->internal->last_discard_sample = mp3->frames * (int64_t)spf;
262  }
263  if (!st->start_time)
264  st->start_time = av_rescale_q(st->internal->start_skip_samples,
265  (AVRational){1, c->sample_rate},
266  st->time_base);
267  av_log(s, AV_LOG_DEBUG, "pad %d %d\n", mp3->start_pad, mp3-> end_pad);
268  }
269 
270  /* Misc */
271  avio_r8(s->pb);
272 
273  /* MP3 gain */
274  avio_r8(s->pb);
275 
276  /* Preset and surround info */
277  avio_rb16(s->pb);
278 
279  /* Music length */
280  avio_rb32(s->pb);
281 
282  /* Music CRC */
283  avio_rb16(s->pb);
284 
285  /* Info Tag CRC */
286  crc = ffio_get_checksum(s->pb);
287  v = avio_rb16(s->pb);
288 
289  if (v == crc) {
290  ff_replaygain_export_raw(st, r_gain, peak, a_gain, 0);
291  av_dict_set(&st->metadata, "encoder", version, 0);
292  }
293 }
294 
295 static void mp3_parse_vbri_tag(AVFormatContext *s, AVStream *st, int64_t base)
296 {
297  uint32_t v;
298  MP3DecContext *mp3 = s->priv_data;
299 
300  /* Check for VBRI tag (always 32 bytes after end of mpegaudio header) */
301  avio_seek(s->pb, base + 4 + 32, SEEK_SET);
302  v = avio_rb32(s->pb);
303  if (v == MKBETAG('V', 'B', 'R', 'I')) {
304  /* Check tag version */
305  if (avio_rb16(s->pb) == 1) {
306  /* skip delay and quality */
307  avio_skip(s->pb, 4);
308  mp3->header_filesize = avio_rb32(s->pb);
309  mp3->frames = avio_rb32(s->pb);
310  }
311  }
312 }
313 
314 /**
315  * Try to find Xing/Info/VBRI tags and compute duration from info therein
316  */
317 static int mp3_parse_vbr_tags(AVFormatContext *s, AVStream *st, int64_t base)
318 {
319  uint32_t v, spf;
320  MPADecodeHeader c;
321  int vbrtag_size = 0;
322  MP3DecContext *mp3 = s->priv_data;
323  int ret;
324 
325  ffio_init_checksum(s->pb, ff_crcA001_update, 0);
326 
327  v = avio_rb32(s->pb);
328 
329  ret = avpriv_mpegaudio_decode_header(&c, v);
330  if (ret < 0)
331  return ret;
332  else if (ret == 0)
333  vbrtag_size = c.frame_size;
334  if (c.layer != 3)
335  return -1;
336 
337  spf = c.lsf ? 576 : 1152; /* Samples per frame, layer 3 */
338 
339  mp3->frames = 0;
340  mp3->header_filesize = 0;
341 
342  mp3_parse_info_tag(s, st, &c, spf);
343  mp3_parse_vbri_tag(s, st, base);
344 
345  if (!mp3->frames && !mp3->header_filesize)
346  return -1;
347 
348  /* Skip the vbr tag frame */
349  avio_seek(s->pb, base + vbrtag_size, SEEK_SET);
350 
351  if (mp3->frames)
352  st->duration = av_rescale_q(mp3->frames, (AVRational){spf, c.sample_rate},
353  st->time_base);
354  if (mp3->header_filesize && mp3->frames && !mp3->is_cbr)
355  st->codecpar->bit_rate = av_rescale(mp3->header_filesize, 8 * c.sample_rate, mp3->frames * (int64_t)spf);
356 
357  return 0;
358 }
359 
360 static int mp3_read_header(AVFormatContext *s)
361 {
362  MP3DecContext *mp3 = s->priv_data;
363  AVStream *st;
364  int64_t off;
365  int ret;
366  int i;
367 
368  s->metadata = s->internal->id3v2_meta;
369  s->internal->id3v2_meta = NULL;
370 
371  st = avformat_new_stream(s, NULL);
372  if (!st)
373  return AVERROR(ENOMEM);
374 
375  st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
376  st->codecpar->codec_id = AV_CODEC_ID_MP3;
377  st->need_parsing = AVSTREAM_PARSE_FULL_RAW;
378  st->start_time = 0;
379 
380  // lcm of all mp3 sample rates
381  avpriv_set_pts_info(st, 64, 1, 14112000);
382 
383  s->pb->maxsize = -1;
384  off = avio_tell(s->pb);
385 
386  if (!av_dict_get(s->metadata, "", NULL, AV_DICT_IGNORE_SUFFIX))
387  ff_id3v1_read(s);
388 
389  if (s->pb->seekable & AVIO_SEEKABLE_NORMAL)
390  mp3->filesize = avio_size(s->pb);
391 
392  if (mp3_parse_vbr_tags(s, st, off) < 0)
393  avio_seek(s->pb, off, SEEK_SET);
394 
395  ret = ff_replaygain_export(st, s->metadata);
396  if (ret < 0)
397  return ret;
398 
399  off = avio_tell(s->pb);
400  for (i = 0; i < 64 * 1024; i++) {
401  uint32_t header, header2;
402  int frame_size;
403  if (!(i&1023))
404  ffio_ensure_seekback(s->pb, i + 1024 + 4);
405  frame_size = check(s->pb, off + i, &header);
406  if (frame_size > 0) {
407  ret = avio_seek(s->pb, off, SEEK_SET);
408  if (ret < 0)
409  return ret;
410  ffio_ensure_seekback(s->pb, i + 1024 + frame_size + 4);
411  ret = check(s->pb, off + i + frame_size, &header2);
412  if (ret >= 0 &&
413  (header & MP3_MASK) == (header2 & MP3_MASK))
414  {
415  av_log(s, i > 0 ? AV_LOG_INFO : AV_LOG_VERBOSE, "Skipping %d bytes of junk at %"PRId64".\n", i, off);
416  ret = avio_seek(s->pb, off + i, SEEK_SET);
417  if (ret < 0)
418  return ret;
419  break;
420  } else if (ret == CHECK_SEEK_FAILED) {
421  av_log(s, AV_LOG_ERROR, "Invalid frame size (%d): Could not seek to %"PRId64".\n", frame_size, off + i + frame_size);
422  return AVERROR(EINVAL);
423  }
424  } else if (frame_size == CHECK_SEEK_FAILED) {
425  av_log(s, AV_LOG_ERROR, "Failed to read frame size: Could not seek to %"PRId64".\n", (int64_t) (i + 1024 + frame_size + 4));
426  return AVERROR(EINVAL);
427  }
428  ret = avio_seek(s->pb, off, SEEK_SET);
429  if (ret < 0)
430  return ret;
431  }
432 
433  // the seek index is relative to the end of the xing vbr headers
434  for (i = 0; i < st->nb_index_entries; i++)
435  st->index_entries[i].pos += avio_tell(s->pb);
436 
437  /* the parameters will be extracted from the compressed bitstream */
438  return 0;
439 }
440 
441 #define MP3_PACKET_SIZE 1024
442 
443 static int mp3_read_packet(AVFormatContext *s, AVPacket *pkt)
444 {
445  MP3DecContext *mp3 = s->priv_data;
446  int ret, size;
447  int64_t pos;
448 
449  size = MP3_PACKET_SIZE;
450  pos = avio_tell(s->pb);
451  if (mp3->filesize > ID3v1_TAG_SIZE && pos < mp3->filesize)
452  size= FFMIN(size, mp3->filesize - pos);
453 
454  ret = av_get_packet(s->pb, pkt, size);
455  if (ret <= 0) {
456  if(ret<0)
457  return ret;
458  return AVERROR_EOF;
459  }
460 
461  pkt->flags &= ~AV_PKT_FLAG_CORRUPT;
462  pkt->stream_index = 0;
463 
464  return ret;
465 }
466 
467 #define SEEK_WINDOW 4096
468 
469 static int check(AVIOContext *pb, int64_t pos, uint32_t *ret_header)
470 {
471  int64_t ret = avio_seek(pb, pos, SEEK_SET);
472  uint8_t header_buf[4];
473  unsigned header;
474  MPADecodeHeader sd;
475  if (ret < 0)
476  return CHECK_SEEK_FAILED;
477 
478  ret = avio_read(pb, &header_buf[0], 4);
479  /* We should always find four bytes for a valid mpa header. */
480  if (ret < 4)
481  return CHECK_SEEK_FAILED;
482 
483  header = AV_RB32(&header_buf[0]);
484  if (ff_mpa_check_header(header) < 0)
485  return CHECK_WRONG_HEADER;
486  if (avpriv_mpegaudio_decode_header(&sd, header) == 1)
487  return CHECK_WRONG_HEADER;
488 
489  if (ret_header)
490  *ret_header = header;
491  return sd.frame_size;
492 }
493 
494 static int64_t mp3_sync(AVFormatContext *s, int64_t target_pos, int flags)
495 {
496  int dir = (flags&AVSEEK_FLAG_BACKWARD) ? -1 : 1;
497  int64_t best_pos;
498  int best_score, i, j;
499  int64_t ret;
500 
501  avio_seek(s->pb, FFMAX(target_pos - SEEK_WINDOW, 0), SEEK_SET);
502  ret = avio_seek(s->pb, target_pos, SEEK_SET);
503  if (ret < 0)
504  return ret;
505 
506 #define MIN_VALID 3
507  best_pos = target_pos;
508  best_score = 999;
509  for (i = 0; i < SEEK_WINDOW; i++) {
510  int64_t pos = target_pos + (dir > 0 ? i - SEEK_WINDOW/4 : -i);
511  int64_t candidate = -1;
512  int score = 999;
513 
514  if (pos < 0)
515  continue;
516 
517  for (j = 0; j < MIN_VALID; j++) {
518  ret = check(s->pb, pos, NULL);
519  if (ret < 0) {
520  if (ret == CHECK_WRONG_HEADER) {
521  break;
522  } else if (ret == CHECK_SEEK_FAILED) {
523  av_log(s, AV_LOG_ERROR, "Could not seek to %"PRId64".\n", pos);
524  return AVERROR(EINVAL);
525  }
526  }
527  if ((target_pos - pos)*dir <= 0 && FFABS(MIN_VALID/2-j) < score) {
528  candidate = pos;
529  score = FFABS(MIN_VALID/2-j);
530  }
531  pos += ret;
532  }
533  if (best_score > score && j == MIN_VALID) {
534  best_pos = candidate;
535  best_score = score;
536  if(score == 0)
537  break;
538  }
539  }
540 
541  return avio_seek(s->pb, best_pos, SEEK_SET);
542 }
543 
544 static int mp3_seek(AVFormatContext *s, int stream_index, int64_t timestamp,
545  int flags)
546 {
547  MP3DecContext *mp3 = s->priv_data;
548  AVIndexEntry *ie, ie1;
549  AVStream *st = s->streams[0];
550  int64_t best_pos;
551  int fast_seek = s->flags & AVFMT_FLAG_FAST_SEEK;
552  int64_t filesize = mp3->header_filesize;
553 
554  if (filesize <= 0) {
555  int64_t size = avio_size(s->pb);
556  if (size > 0 && size > s->internal->data_offset)
557  filesize = size - s->internal->data_offset;
558  }
559 
560  if (mp3->xing_toc && (mp3->usetoc || (fast_seek && !mp3->is_cbr))) {
561  int64_t ret = av_index_search_timestamp(st, timestamp, flags);
562 
563  // NOTE: The MP3 TOC is not a precise lookup table. Accuracy is worse
564  // for bigger files.
565  av_log(s, AV_LOG_WARNING, "Using MP3 TOC to seek; may be imprecise.\n");
566 
567  if (ret < 0)
568  return ret;
569 
570  ie = &st->index_entries[ret];
571  } else if (fast_seek && st->duration > 0 && filesize > 0) {
572  if (!mp3->is_cbr)
573  av_log(s, AV_LOG_WARNING, "Using scaling to seek VBR MP3; may be imprecise.\n");
574 
575  ie = &ie1;
576  timestamp = av_clip64(timestamp, 0, st->duration);
577  ie->timestamp = timestamp;
578  ie->pos = av_rescale(timestamp, filesize, st->duration) + s->internal->data_offset;
579  } else {
580  return -1; // generic index code
581  }
582 
583  best_pos = mp3_sync(s, ie->pos, flags);
584  if (best_pos < 0)
585  return best_pos;
586 
587  if (mp3->is_cbr && ie == &ie1 && mp3->frames) {
588  int frame_duration = av_rescale(st->duration, 1, mp3->frames);
589  ie1.timestamp = frame_duration * av_rescale(best_pos - s->internal->data_offset, mp3->frames, mp3->header_filesize);
590  }
591 
592  ff_update_cur_dts(s, st, ie->timestamp);
593  return 0;
594 }
595 
596 static const AVOption options[] = {
597  { "usetoc", "use table of contents", offsetof(MP3DecContext, usetoc), AV_OPT_TYPE_BOOL, {.i64 = 0}, 0, 1, AV_OPT_FLAG_DECODING_PARAM},
598  { NULL },
599 };
600 
601 static const AVClass demuxer_class = {
602  .class_name = "mp3",
603  .item_name = av_default_item_name,
604  .option = options,
605  .version = LIBAVUTIL_VERSION_INT,
606  .category = AV_CLASS_CATEGORY_DEMUXER,
607 };
608 
609 AVInputFormat ff_mp3_demuxer = {
610  .name = "mp3",
611  .long_name = NULL_IF_CONFIG_SMALL("MP2/3 (MPEG audio layer 2/3)"),
612  .read_probe = mp3_read_probe,
613  .read_header = mp3_read_header,
614  .read_packet = mp3_read_packet,
615  .read_seek = mp3_seek,
616  .priv_data_size = sizeof(MP3DecContext),
617  .flags = AVFMT_GENERIC_INDEX,
618  .extensions = "mp2,mp3,m2a,mpa", /* XXX: use probe */
619  .priv_class = &demuxer_class,
620 };
AVStream::index_entries
AVIndexEntry * index_entries
Only used if the format does not support seeking natively.
Definition: avformat.h:1090
AV_LOG_WARNING
#define AV_LOG_WARNING
Something somehow does not look correct.
Definition: log.h:200
ID3v1_TAG_SIZE
#define ID3v1_TAG_SIZE
Definition: id3v1.h:27
AVERROR
Filter the word “frame” indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a all references to both lists are replaced with a reference to the intersection And when a single format is eventually chosen for a link amongst the remaining all references to the list are updated That means that if a filter requires that its input and output have the same format amongst a supported all it has to do is use a reference to the same list of formats query_formats can leave some formats unset and return AVERROR(EAGAIN) to cause the negotiation mechanism toagain later. That can be used by filters with complex requirements to use the format negotiated on one link to set the formats supported on another. Frame references ownership and permissions
opt.h
avformat_new_stream
AVStream * avformat_new_stream(AVFormatContext *s, const AVCodec *c)
Add a new stream to a media file.
Definition: utils.c:4509
xing_offtbl
static const uint8_t xing_offtbl[2][2]
Definition: mp3enc.c:138
AVCodecParameters::codec_type
enum AVMediaType codec_type
General type of the encoded data.
Definition: codec_par.h:56
XING_FLAC_QSCALE
#define XING_FLAC_QSCALE
Definition: mp3dec.c:41
demuxer_class
static const AVClass demuxer_class
Definition: mp3dec.c:601
mp3_read_packet
static int mp3_read_packet(AVFormatContext *s, AVPacket *pkt)
Definition: mp3dec.c:443
ff_replaygain_export
int ff_replaygain_export(AVStream *st, AVDictionary *metadata)
Parse replaygain tags and export them as per-stream side data.
Definition: replaygain.c:91
AVERROR_EOF
#define AVERROR_EOF
End of file.
Definition: error.h:55
MP3DecContext
Definition: mp3dec.c:46
id3v2.h
ff_replaygain_export_raw
int ff_replaygain_export_raw(AVStream *st, int32_t tg, uint32_t tp, int32_t ag, uint32_t ap)
Export already decoded replaygain values as per-stream side data.
Definition: replaygain.c:70
mpegaudiodecheader.h
ff_id3v1_read
void ff_id3v1_read(AVFormatContext *s)
Read an ID3v1 tag.
Definition: id3v1.c:279
AVStream::internal
AVStreamInternal * internal
An opaque field for libavformat internal usage.
Definition: avformat.h:1113
AVOption
AVOption.
Definition: opt.h:248
b
#define b
Definition: input.c:41
MPADecodeHeader
Definition: mpegaudiodecheader.h:46
AV_DICT_IGNORE_SUFFIX
#define AV_DICT_IGNORE_SUFFIX
Return first entry in a dictionary whose first part corresponds to the search key,...
Definition: dict.h:70
AV_LOG_VERBOSE
#define AV_LOG_VERBOSE
Detailed information.
Definition: log.h:210
base
uint8_t base
Definition: vp3data.h:141
mathematics.h
AVProbeData::buf_size
int buf_size
Size of buf except extra allocated bytes.
Definition: avformat.h:444
MP3_MASK
#define MP3_MASK
Definition: mpegaudiodecheader.h:32
id3v1.h
avio_size
int64_t avio_size(AVIOContext *s)
Get the filesize.
Definition: aviobuf.c:342
ffio_get_checksum
unsigned long ffio_get_checksum(AVIOContext *s)
Definition: aviobuf.c:604
AVIndexEntry
Definition: avformat.h:803
AVINDEX_KEYFRAME
#define AVINDEX_KEYFRAME
Definition: avformat.h:811
crc.h
MIDDLE_BITS
#define MIDDLE_BITS(k, m, n)
XING_FLAG_FRAMES
#define XING_FLAG_FRAMES
Definition: mp3dec.c:38
av_add_index_entry
int av_add_index_entry(AVStream *st, int64_t pos, int64_t timestamp, int size, int distance, int flags)
Add an index entry into a sorted list.
Definition: utils.c:2013
frames
if it could not because there are no more frames
Definition: filter_design.txt:266
avio_tell
static av_always_inline int64_t avio_tell(AVIOContext *s)
ftell() equivalent for AVIOContext.
Definition: avio.h:557
AVFMT_GENERIC_INDEX
#define AVFMT_GENERIC_INDEX
Use generic index building code.
Definition: avformat.h:463
AV_CODEC_ID_MP3
@ AV_CODEC_ID_MP3
preferred ID for decoding MPEG audio layer 1, 2 or 3
Definition: codec_id.h:425
AVStream::duration
int64_t duration
Decoding: duration of the stream, in stream time base.
Definition: avformat.h:922
read_xing_toc
static void read_xing_toc(AVFormatContext *s, int64_t filesize, int64_t duration)
Definition: mp3dec.c:132
av_clip64
#define av_clip64
Definition: common.h:125
MP3DecContext::filesize
int64_t filesize
Definition: mp3dec.c:48
avio_rb32
unsigned int avio_rb32(AVIOContext *s)
Definition: aviobuf.c:781
pkt
AVPacket * pkt
Definition: movenc.c:59
AV_LOG_ERROR
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:194
avpriv_mpegaudio_decode_header
int avpriv_mpegaudio_decode_header(MPADecodeHeader *s, uint32_t header)
Definition: mpegaudiodecheader.c:36
AVInputFormat
Definition: avformat.h:640
AV_PKT_FLAG_CORRUPT
#define AV_PKT_FLAG_CORRUPT
The packet content is corrupted.
Definition: packet.h:411
SEEK_WINDOW
#define SEEK_WINDOW
Definition: mp3dec.c:467
duration
int64_t duration
Definition: movenc.c:64
av_dict_get
AVDictionaryEntry * av_dict_get(const AVDictionary *m, const char *key, const AVDictionaryEntry *prev, int flags)
Get a dictionary entry with matching key.
Definition: dict.c:40
MP3_PACKET_SIZE
#define MP3_PACKET_SIZE
Definition: mp3dec.c:441
intreadwrite.h
s
#define s(width, name)
Definition: cbs_vp9.c:257
AVInputFormat::name
const char * name
A comma separated list of short names for the format.
Definition: avformat.h:645
AVProbeData::buf
unsigned char * buf
Buffer must have AVPROBE_PADDING_SIZE of extra allocated bytes filled with zero.
Definition: avformat.h:443
frame_size
int frame_size
Definition: mxfenc.c:2206
AVMEDIA_TYPE_AUDIO
@ AVMEDIA_TYPE_AUDIO
Definition: avutil.h:202
AVIndexEntry::timestamp
int64_t timestamp
Timestamp in AVStream.time_base units, preferably the time from which on correctly decoded frames are...
Definition: avformat.h:805
MP3DecContext::end_pad
int end_pad
Definition: mp3dec.c:51
AV_LOG_DEBUG
#define AV_LOG_DEBUG
Stuff which is only useful for libav* developers.
Definition: log.h:215
AVStream::need_parsing
enum AVStreamParseType need_parsing
Definition: avformat.h:1081
av_rescale_q
int64_t av_rescale_q(int64_t a, AVRational bq, AVRational cq)
Rescale a 64-bit integer by 2 rational numbers.
Definition: mathematics.c:142
MP3DecContext::xing_toc
int xing_toc
Definition: mp3dec.c:49
XING_FLAG_TOC
#define XING_FLAG_TOC
Definition: mp3dec.c:40
fsize
static int64_t fsize(FILE *f)
Definition: audiomatch.c:29
int32_t
int32_t
Definition: audio_convert.c:194
AV_CLASS_CATEGORY_DEMUXER
@ AV_CLASS_CATEGORY_DEMUXER
Definition: log.h:34
FFABS
#define FFABS(a)
Absolute value, Note, INT_MIN / INT64_MIN result in undefined behavior as they are not representable ...
Definition: common.h:72
AVFormatContext
Format I/O context.
Definition: avformat.h:1232
internal.h
ff_update_cur_dts
void ff_update_cur_dts(AVFormatContext *s, AVStream *ref_st, int64_t timestamp)
Update cur_dts of all streams based on the given timestamp and AVStream.
Definition: utils.c:1927
AVStream::codecpar
AVCodecParameters * codecpar
Codec parameters associated with this stream.
Definition: avformat.h:1038
LIBAVUTIL_VERSION_INT
#define LIBAVUTIL_VERSION_INT
Definition: version.h:85
AVSEEK_FLAG_BACKWARD
#define AVSEEK_FLAG_BACKWARD
Definition: avformat.h:2415
AVClass
Describe the class of an AVClass context structure.
Definition: log.h:67
AVStream::time_base
AVRational time_base
This is the fundamental unit of time (in seconds) in terms of which frame timestamps are represented.
Definition: avformat.h:902
NULL
#define NULL
Definition: coverity.c:32
AVRational
Rational number (pair of numerator and denominator).
Definition: rational.h:58
ff_mp3_demuxer
AVInputFormat ff_mp3_demuxer
Definition: mp3dec.c:609
av_default_item_name
const char * av_default_item_name(void *ptr)
Return the context name.
Definition: log.c:235
AVProbeData
This structure contains the data a format has to probe a file.
Definition: avformat.h:441
AVStream::metadata
AVDictionary * metadata
Definition: avformat.h:937
c
Undefined Behavior In the C some operations are like signed integer dereferencing freed accessing outside allocated Undefined Behavior must not occur in a C it is not safe even if the output of undefined operations is unused The unsafety may seem nit picking but Optimizing compilers have in fact optimized code on the assumption that no undefined Behavior occurs Optimizing code based on wrong assumptions can and has in some cases lead to effects beyond the output of computations The signed integer overflow problem in speed critical code Code which is highly optimized and works with signed integers sometimes has the problem that often the output of the computation does not c
Definition: undefined.txt:32
AVPROBE_SCORE_EXTENSION
#define AVPROBE_SCORE_EXTENSION
score for file extension
Definition: avformat.h:451
MP3DecContext::start_pad
int start_pad
Definition: mp3dec.c:50
mp3_parse_vbr_tags
static int mp3_parse_vbr_tags(AVFormatContext *s, AVStream *st, int64_t base)
Try to find Xing/Info/VBRI tags and compute duration from info therein.
Definition: mp3dec.c:317
AVIOContext
Bytestream IO Context.
Definition: avio.h:161
avio_rb24
unsigned int avio_rb24(AVIOContext *s)
Definition: aviobuf.c:774
ff_mpa_check_header
static int ff_mpa_check_header(uint32_t header)
Definition: mpegaudiodecheader.h:61
NULL_IF_CONFIG_SMALL
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification.
Definition: internal.h:117
AVStream::nb_index_entries
int nb_index_entries
Definition: avformat.h:1092
mp3_read_header
static int mp3_read_header(AVFormatContext *s)
Definition: mp3dec.c:360
FFMAX
#define FFMAX(a, b)
Definition: common.h:103
avpriv_set_pts_info
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:4945
MP3DecContext::frames
unsigned frames
Definition: mp3dec.c:53
AVStreamInternal::last_discard_sample
int64_t last_discard_sample
The sample after last sample that is intended to be discarded after first_discard_sample.
Definition: internal.h:282
size
int size
Definition: twinvq_data.h:10344
CHECK_SEEK_FAILED
@ CHECK_SEEK_FAILED
Definition: mp3dec.c:60
ID3v2_DEFAULT_MAGIC
#define ID3v2_DEFAULT_MAGIC
Default magic bytes for ID3v2 header: "ID3".
Definition: id3v2.h:35
AV_RB32
uint64_t_TMPL AV_WL64 unsigned int_TMPL AV_WL32 unsigned int_TMPL AV_WL24 unsigned int_TMPL AV_WL16 uint64_t_TMPL AV_WB64 unsigned int_TMPL AV_RB32
Definition: bytestream.h:96
MKBETAG
#define MKBETAG(a, b, c, d)
Definition: common.h:479
XING_FLAG_SIZE
#define XING_FLAG_SIZE
Definition: mp3dec.c:39
ffio_init_checksum
void ffio_init_checksum(AVIOContext *s, unsigned long(*update_checksum)(unsigned long c, const uint8_t *p, unsigned int len), unsigned long checksum)
Definition: aviobuf.c:612
header
static const uint8_t header[24]
Definition: sdr2.c:67
avio_r8
int avio_r8(AVIOContext *s)
Definition: aviobuf.c:624
FFMIN
#define FFMIN(a, b)
Definition: common.h:105
ffio_ensure_seekback
int ffio_ensure_seekback(AVIOContext *s, int64_t buf_size)
Ensures that the requested seekback buffer size will be available.
Definition: aviobuf.c:998
XING_TOC_COUNT
#define XING_TOC_COUNT
Definition: mp3dec.c:43
AVPacket::flags
int flags
A combination of AV_PKT_FLAG values.
Definition: packet.h:375
version
version
Definition: libkvazaar.c:326
AV_LOG_INFO
#define AV_LOG_INFO
Standard information.
Definition: log.h:205
MP3DecContext::is_cbr
int is_cbr
Definition: mp3dec.c:55
PROBE_BUF_MAX
#define PROBE_BUF_MAX
Definition: internal.h:34
AVFMT_FLAG_FAST_SEEK
#define AVFMT_FLAG_FAST_SEEK
Enable fast, but inaccurate seeks for some formats.
Definition: avformat.h:1391
i
int i
Definition: input.c:407
avio_internal.h
AVStreamInternal::start_skip_samples
int64_t start_skip_samples
If not 0, the number of samples that should be skipped from the start of the stream (the samples are ...
Definition: internal.h:267
available
if no frame is available
Definition: filter_design.txt:166
mp3_parse_info_tag
static void mp3_parse_info_tag(AVFormatContext *s, AVStream *st, MPADecodeHeader *c, uint32_t spf)
Definition: mp3dec.c:157
mp3_seek
static int mp3_seek(AVFormatContext *s, int stream_index, int64_t timestamp, int flags)
Definition: mp3dec.c:544
delta
float delta
Definition: vorbis_enc_data.h:457
AV_OPT_FLAG_DECODING_PARAM
#define AV_OPT_FLAG_DECODING_PARAM
a generic parameter which can be set by the user for demuxing or decoding
Definition: opt.h:279
mp3_sync
static int64_t mp3_sync(AVFormatContext *s, int64_t target_pos, int flags)
Definition: mp3dec.c:494
uint8_t
uint8_t
Definition: audio_convert.c:194
mp3_read_probe
static int mp3_read_probe(const AVProbeData *p)
Definition: mp3dec.c:67
ff_crcA001_update
unsigned long ff_crcA001_update(unsigned long checksum, const uint8_t *buf, unsigned int len)
Definition: aviobuf.c:598
av_rescale
int64_t av_rescale(int64_t a, int64_t b, int64_t c)
Rescale a 64-bit integer with rounding to nearest.
Definition: mathematics.c:129
av_get_packet
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
avcodec.h
ff_id3v2_tag_len
int ff_id3v2_tag_len(const uint8_t *buf)
Get the length of an ID3v2 tag.
Definition: id3v2.c:156
ret
ret
Definition: filter_design.txt:187
AVStream
Stream structure.
Definition: avformat.h:873
avio_seek
int64_t avio_seek(AVIOContext *s, int64_t offset, int whence)
fseek() equivalent for AVIOContext.
Definition: aviobuf.c:253
AVClass::class_name
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
avio_rb16
unsigned int avio_rb16(AVIOContext *s)
Definition: aviobuf.c:766
CheckRet
CheckRet
Definition: mp3dec.c:58
pos
unsigned int pos
Definition: spdifenc.c:412
avformat.h
dict.h
AVStreamInternal::first_discard_sample
int64_t first_discard_sample
If not 0, the first audio sample that should be discarded from the stream.
Definition: internal.h:275
AVIO_SEEKABLE_NORMAL
#define AVIO_SEEKABLE_NORMAL
Seeking works like for a local file.
Definition: avio.h:40
avio_read
int avio_read(AVIOContext *s, unsigned char *buf, int size)
Read size bytes from AVIOContext into buf.
Definition: aviobuf.c:633
mp3_parse_vbri_tag
static void mp3_parse_vbri_tag(AVFormatContext *s, AVStream *st, int64_t base)
Definition: mp3dec.c:295
MP3DecContext::header_filesize
unsigned header_filesize
Definition: mp3dec.c:54
AVIndexEntry::pos
int64_t pos
Definition: avformat.h:804
AVSTREAM_PARSE_FULL_RAW
@ AVSTREAM_PARSE_FULL_RAW
full parsing and repack with timestamp and position generation by parser for raw this assumes that ea...
Definition: avformat.h:798
AVPacket::stream_index
int stream_index
Definition: packet.h:371
avio_skip
int64_t avio_skip(AVIOContext *s, int64_t offset)
Skip given number of bytes forward.
Definition: aviobuf.c:337
MP3DecContext::usetoc
int usetoc
Definition: mp3dec.c:52
options
static const AVOption options[]
Definition: mp3dec.c:596
check
static int check(AVIOContext *pb, int64_t pos, uint32_t *header)
Definition: mp3dec.c:469
AVCodecParameters::codec_id
enum AVCodecID codec_id
Specific type of the encoded data (the codec used).
Definition: codec_par.h:60
AVPacket
This structure stores compressed data.
Definition: packet.h:346
AV_OPT_TYPE_BOOL
@ AV_OPT_TYPE_BOOL
Definition: opt.h:242
av_dict_set
int av_dict_set(AVDictionary **pm, const char *key, const char *value, int flags)
Set the given entry in *pm, overwriting an existing entry.
Definition: dict.c:70
replaygain.h
flags
#define flags(name, subs,...)
Definition: cbs_av1.c:561
AVCodecParameters::bit_rate
int64_t bit_rate
The average bitrate of the encoded data (in bits per second).
Definition: codec_par.h:89
av_log
#define av_log(a,...)
Definition: tableprint_vlc.h:28
h
h
Definition: vp9dsp_template.c:2038
AVStream::start_time
int64_t start_time
Decoding: pts of the first frame of the stream in presentation order, in stream time base.
Definition: avformat.h:912
avstring.h
MIN_VALID
#define MIN_VALID
ff_id3v2_match
int ff_id3v2_match(const uint8_t *buf, const char *magic)
Detect ID3v2 Header.
Definition: id3v2.c:143
av_index_search_timestamp
int av_index_search_timestamp(AVStream *st, int64_t timestamp, int flags)
Get the index for a specific timestamp.
Definition: utils.c:2130
CHECK_WRONG_HEADER
@ CHECK_WRONG_HEADER
Definition: mp3dec.c:59
min
float min
Definition: vorbis_enc_data.h:456
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