mpeg.c
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1 /*
2  * MPEG1/2 demuxer
3  * Copyright (c) 2000, 2001, 2002 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 "internal.h"
24 #include "mpeg.h"
25 
26 #undef NDEBUG
27 #include <assert.h>
28 
29 /*********************************************/
30 /* demux code */
31 
32 #define MAX_SYNC_SIZE 100000
33 
34 static int check_pes(uint8_t *p, uint8_t *end){
35  int pes1;
36  int pes2= (p[3] & 0xC0) == 0x80
37  && (p[4] & 0xC0) != 0x40
38  &&((p[4] & 0xC0) == 0x00 || (p[4]&0xC0)>>2 == (p[6]&0xF0));
39 
40  for(p+=3; p<end && *p == 0xFF; p++);
41  if((*p&0xC0) == 0x40) p+=2;
42  if((*p&0xF0) == 0x20){
43  pes1= p[0]&p[2]&p[4]&1;
44  }else if((*p&0xF0) == 0x30){
45  pes1= p[0]&p[2]&p[4]&p[5]&p[7]&p[9]&1;
46  }else
47  pes1 = *p == 0x0F;
48 
49  return pes1||pes2;
50 }
51 
52 static int check_pack_header(const uint8_t *buf) {
53  return (buf[1] & 0xC0) == 0x40 || (buf[1] & 0xF0) == 0x20;
54 }
55 
56 static int mpegps_probe(AVProbeData *p)
57 {
58  uint32_t code= -1;
59  int sys=0, pspack=0, priv1=0, vid=0, audio=0, invalid=0;
60  int i;
61  int score=0;
62 
63  for(i=0; i<p->buf_size; i++){
64  code = (code<<8) + p->buf[i];
65  if ((code & 0xffffff00) == 0x100) {
66  int len= p->buf[i+1] << 8 | p->buf[i+2];
67  int pes= check_pes(p->buf+i, p->buf+p->buf_size);
68  int pack = check_pack_header(p->buf+i);
69 
70  if(code == SYSTEM_HEADER_START_CODE) sys++;
71  else if(code == PACK_START_CODE && pack) pspack++;
72  else if((code & 0xf0) == VIDEO_ID && pes) vid++;
73  // skip pes payload to avoid start code emulation for private
74  // and audio streams
75  else if((code & 0xe0) == AUDIO_ID && pes) {audio++; i+=len;}
76  else if(code == PRIVATE_STREAM_1 && pes) {priv1++; i+=len;}
77 
78  else if((code & 0xf0) == VIDEO_ID && !pes) invalid++;
79  else if((code & 0xe0) == AUDIO_ID && !pes) invalid++;
80  else if(code == PRIVATE_STREAM_1 && !pes) invalid++;
81  }
82  }
83 
84  if(vid+audio > invalid) /* invalid VDR files nd short PES streams */
85  score= AVPROBE_SCORE_MAX/4;
86 
87  if(sys>invalid && sys*9 <= pspack*10)
88  return pspack > 2 ? AVPROBE_SCORE_MAX/2+2 : AVPROBE_SCORE_MAX/4; // +1 for .mpg
89  if(pspack > invalid && (priv1+vid+audio)*10 >= pspack*9)
90  return pspack > 2 ? AVPROBE_SCORE_MAX/2+2 : AVPROBE_SCORE_MAX/4; // +1 for .mpg
91  if((!!vid ^ !!audio) && (audio > 4 || vid > 1) && !sys && !pspack && p->buf_size>2048 && vid + audio > invalid) /* PES stream */
92  return (audio > 12 || vid > 3) ? AVPROBE_SCORE_MAX/2+2 : AVPROBE_SCORE_MAX/4;
93 
94  //02-Penguin.flac has sys:0 priv1:0 pspack:0 vid:0 audio:1
95  //mp3_misidentified_2.mp3 has sys:0 priv1:0 pspack:0 vid:0 audio:6
96  return score;
97 }
98 
99 
100 typedef struct MpegDemuxContext {
102  unsigned char psm_es_type[256];
103  int sofdec;
105 
107 {
108  MpegDemuxContext *m = s->priv_data;
109  const char *sofdec = "Sofdec";
110  int v, i = 0;
111 
112  m->header_state = 0xff;
114 
115  m->sofdec = -1;
116  do {
117  v = avio_r8(s->pb);
118  m->header_state = m->header_state << 8 | v;
119  m->sofdec++;
120  } while (v == sofdec[i] && i++ < 6);
121 
122  m->sofdec = (m->sofdec == 6) ? 1 : 0;
123 
124  /* no need to do more */
125  return 0;
126 }
127 
128 static int64_t get_pts(AVIOContext *pb, int c)
129 {
130  uint8_t buf[5];
131 
132  buf[0] = c<0 ? avio_r8(pb) : c;
133  avio_read(pb, buf+1, 4);
134 
135  return ff_parse_pes_pts(buf);
136 }
137 
138 static int find_next_start_code(AVIOContext *pb, int *size_ptr,
139  int32_t *header_state)
140 {
141  unsigned int state, v;
142  int val, n;
143 
144  state = *header_state;
145  n = *size_ptr;
146  while (n > 0) {
147  if (pb->eof_reached)
148  break;
149  v = avio_r8(pb);
150  n--;
151  if (state == 0x000001) {
152  state = ((state << 8) | v) & 0xffffff;
153  val = state;
154  goto found;
155  }
156  state = ((state << 8) | v) & 0xffffff;
157  }
158  val = -1;
159  found:
160  *header_state = state;
161  *size_ptr = n;
162  return val;
163 }
164 
172 {
173  int psm_length, ps_info_length, es_map_length;
174 
175  psm_length = avio_rb16(pb);
176  avio_r8(pb);
177  avio_r8(pb);
178  ps_info_length = avio_rb16(pb);
179 
180  /* skip program_stream_info */
181  avio_skip(pb, ps_info_length);
182  es_map_length = avio_rb16(pb);
183 
184  /* at least one es available? */
185  while (es_map_length >= 4){
186  unsigned char type = avio_r8(pb);
187  unsigned char es_id = avio_r8(pb);
188  uint16_t es_info_length = avio_rb16(pb);
189  /* remember mapping from stream id to stream type */
190  m->psm_es_type[es_id] = type;
191  /* skip program_stream_info */
192  avio_skip(pb, es_info_length);
193  es_map_length -= 4 + es_info_length;
194  }
195  avio_rb32(pb); /* crc32 */
196  return 2 + psm_length;
197 }
198 
199 /* read the next PES header. Return its position in ppos
200  (if not NULL), and its start code, pts and dts.
201  */
203  int64_t *ppos, int *pstart_code,
204  int64_t *ppts, int64_t *pdts)
205 {
206  MpegDemuxContext *m = s->priv_data;
207  int len, size, startcode, c, flags, header_len;
208  int pes_ext, ext2_len, id_ext, skip;
209  int64_t pts, dts;
210  int64_t last_sync= avio_tell(s->pb);
211 
212  error_redo:
213  avio_seek(s->pb, last_sync, SEEK_SET);
214  redo:
215  /* next start code (should be immediately after) */
216  m->header_state = 0xff;
217  size = MAX_SYNC_SIZE;
218  startcode = find_next_start_code(s->pb, &size, &m->header_state);
219  last_sync = avio_tell(s->pb);
220  if (startcode < 0){
221  if(s->pb->eof_reached)
222  return AVERROR_EOF;
223  //FIXME we should remember header_state
224  return AVERROR(EAGAIN);
225  }
226 
227  if (startcode == PACK_START_CODE)
228  goto redo;
229  if (startcode == SYSTEM_HEADER_START_CODE)
230  goto redo;
231  if (startcode == PADDING_STREAM) {
232  avio_skip(s->pb, avio_rb16(s->pb));
233  goto redo;
234  }
235  if (startcode == PRIVATE_STREAM_2) {
236  len = avio_rb16(s->pb);
237  if (!m->sofdec) {
238  while (len-- >= 6) {
239  if (avio_r8(s->pb) == 'S') {
240  uint8_t buf[5];
241  avio_read(s->pb, buf, sizeof(buf));
242  m->sofdec = !memcmp(buf, "ofdec", 5);
243  len -= sizeof(buf);
244  break;
245  }
246  }
247  m->sofdec -= !m->sofdec;
248  }
249  avio_skip(s->pb, len);
250  goto redo;
251  }
252  if (startcode == PROGRAM_STREAM_MAP) {
253  mpegps_psm_parse(m, s->pb);
254  goto redo;
255  }
256 
257  /* find matching stream */
258  if (!((startcode >= 0x1c0 && startcode <= 0x1df) ||
259  (startcode >= 0x1e0 && startcode <= 0x1ef) ||
260  (startcode == 0x1bd) || (startcode == 0x1fd)))
261  goto redo;
262  if (ppos) {
263  *ppos = avio_tell(s->pb) - 4;
264  }
265  len = avio_rb16(s->pb);
266  pts =
267  dts = AV_NOPTS_VALUE;
268  /* stuffing */
269  for(;;) {
270  if (len < 1)
271  goto error_redo;
272  c = avio_r8(s->pb);
273  len--;
274  /* XXX: for mpeg1, should test only bit 7 */
275  if (c != 0xff)
276  break;
277  }
278  if ((c & 0xc0) == 0x40) {
279  /* buffer scale & size */
280  avio_r8(s->pb);
281  c = avio_r8(s->pb);
282  len -= 2;
283  }
284  if ((c & 0xe0) == 0x20) {
285  dts = pts = get_pts(s->pb, c);
286  len -= 4;
287  if (c & 0x10){
288  dts = get_pts(s->pb, -1);
289  len -= 5;
290  }
291  } else if ((c & 0xc0) == 0x80) {
292  /* mpeg 2 PES */
293  flags = avio_r8(s->pb);
294  header_len = avio_r8(s->pb);
295  len -= 2;
296  if (header_len > len)
297  goto error_redo;
298  len -= header_len;
299  if (flags & 0x80) {
300  dts = pts = get_pts(s->pb, -1);
301  header_len -= 5;
302  if (flags & 0x40) {
303  dts = get_pts(s->pb, -1);
304  header_len -= 5;
305  }
306  }
307  if (flags & 0x3f && header_len == 0){
308  flags &= 0xC0;
309  av_log(s, AV_LOG_WARNING, "Further flags set but no bytes left\n");
310  }
311  if (flags & 0x01) { /* PES extension */
312  pes_ext = avio_r8(s->pb);
313  header_len--;
314  /* Skip PES private data, program packet sequence counter and P-STD buffer */
315  skip = (pes_ext >> 4) & 0xb;
316  skip += skip & 0x9;
317  if (pes_ext & 0x40 || skip > header_len){
318  av_log(s, AV_LOG_WARNING, "pes_ext %X is invalid\n", pes_ext);
319  pes_ext=skip=0;
320  }
321  avio_skip(s->pb, skip);
322  header_len -= skip;
323 
324  if (pes_ext & 0x01) { /* PES extension 2 */
325  ext2_len = avio_r8(s->pb);
326  header_len--;
327  if ((ext2_len & 0x7f) > 0) {
328  id_ext = avio_r8(s->pb);
329  if ((id_ext & 0x80) == 0)
330  startcode = ((startcode & 0xff) << 8) | id_ext;
331  header_len--;
332  }
333  }
334  }
335  if(header_len < 0)
336  goto error_redo;
337  avio_skip(s->pb, header_len);
338  }
339  else if( c!= 0xf )
340  goto redo;
341 
342  if (startcode == PRIVATE_STREAM_1 && !m->psm_es_type[startcode & 0xff]) {
343  startcode = avio_r8(s->pb);
344  len--;
345  if (startcode >= 0x80 && startcode <= 0xcf) {
346  /* audio: skip header */
347  avio_r8(s->pb);
348  avio_r8(s->pb);
349  avio_r8(s->pb);
350  len -= 3;
351  if (startcode >= 0xb0 && startcode <= 0xbf) {
352  /* MLP/TrueHD audio has a 4-byte header */
353  avio_r8(s->pb);
354  len--;
355  }
356  }
357  }
358  if(len<0)
359  goto error_redo;
360  if(dts != AV_NOPTS_VALUE && ppos){
361  int i;
362  for(i=0; i<s->nb_streams; i++){
363  if(startcode == s->streams[i]->id &&
364  s->pb->seekable /* index useless on streams anyway */) {
365  ff_reduce_index(s, i);
366  av_add_index_entry(s->streams[i], *ppos, dts, 0, 0, AVINDEX_KEYFRAME /* FIXME keyframe? */);
367  }
368  }
369  }
370 
371  *pstart_code = startcode;
372  *ppts = pts;
373  *pdts = dts;
374  return len;
375 }
376 
378  AVPacket *pkt)
379 {
380  MpegDemuxContext *m = s->priv_data;
381  AVStream *st;
382  int len, startcode, i, es_type, ret;
384  enum AVMediaType type;
385  int64_t pts, dts, dummy_pos; //dummy_pos is needed for the index building to work
386  uint8_t av_uninit(dvdaudio_substream_type);
387 
388  redo:
389  len = mpegps_read_pes_header(s, &dummy_pos, &startcode, &pts, &dts);
390  if (len < 0)
391  return len;
392 
393  if(startcode == 0x1bd) {
394  dvdaudio_substream_type = avio_r8(s->pb);
395  avio_skip(s->pb, 3);
396  len -= 4;
397  }
398 
399  /* now find stream */
400  for(i=0;i<s->nb_streams;i++) {
401  st = s->streams[i];
402  if (st->id == startcode)
403  goto found;
404  }
405 
406  es_type = m->psm_es_type[startcode & 0xff];
407  if(es_type > 0 && es_type != STREAM_TYPE_PRIVATE_DATA){
408  if(es_type == STREAM_TYPE_VIDEO_MPEG1){
409  codec_id = AV_CODEC_ID_MPEG2VIDEO;
410  type = AVMEDIA_TYPE_VIDEO;
411  } else if(es_type == STREAM_TYPE_VIDEO_MPEG2){
412  codec_id = AV_CODEC_ID_MPEG2VIDEO;
413  type = AVMEDIA_TYPE_VIDEO;
414  } else if(es_type == STREAM_TYPE_AUDIO_MPEG1 ||
415  es_type == STREAM_TYPE_AUDIO_MPEG2){
416  codec_id = AV_CODEC_ID_MP3;
417  type = AVMEDIA_TYPE_AUDIO;
418  } else if(es_type == STREAM_TYPE_AUDIO_AAC){
419  codec_id = AV_CODEC_ID_AAC;
420  type = AVMEDIA_TYPE_AUDIO;
421  } else if(es_type == STREAM_TYPE_VIDEO_MPEG4){
422  codec_id = AV_CODEC_ID_MPEG4;
423  type = AVMEDIA_TYPE_VIDEO;
424  } else if(es_type == STREAM_TYPE_VIDEO_H264){
425  codec_id = AV_CODEC_ID_H264;
426  type = AVMEDIA_TYPE_VIDEO;
427  } else if(es_type == STREAM_TYPE_AUDIO_AC3){
428  codec_id = AV_CODEC_ID_AC3;
429  type = AVMEDIA_TYPE_AUDIO;
430  } else {
431  goto skip;
432  }
433  } else if (startcode >= 0x1e0 && startcode <= 0x1ef) {
434  static const unsigned char avs_seqh[4] = { 0, 0, 1, 0xb0 };
435  unsigned char buf[8];
436  avio_read(s->pb, buf, 8);
437  avio_seek(s->pb, -8, SEEK_CUR);
438  if(!memcmp(buf, avs_seqh, 4) && (buf[6] != 0 || buf[7] != 1))
439  codec_id = AV_CODEC_ID_CAVS;
440  else
441  codec_id = AV_CODEC_ID_PROBE;
442  type = AVMEDIA_TYPE_VIDEO;
443  } else if (startcode >= 0x1c0 && startcode <= 0x1df) {
444  type = AVMEDIA_TYPE_AUDIO;
445  codec_id = m->sofdec > 0 ? AV_CODEC_ID_ADPCM_ADX : AV_CODEC_ID_MP2;
446  } else if (startcode >= 0x80 && startcode <= 0x87) {
447  type = AVMEDIA_TYPE_AUDIO;
448  codec_id = AV_CODEC_ID_AC3;
449  } else if ( ( startcode >= 0x88 && startcode <= 0x8f)
450  ||( startcode >= 0x98 && startcode <= 0x9f)) {
451  /* 0x90 - 0x97 is reserved for SDDS in DVD specs */
452  type = AVMEDIA_TYPE_AUDIO;
453  codec_id = AV_CODEC_ID_DTS;
454  } else if (startcode >= 0xa0 && startcode <= 0xaf) {
455  type = AVMEDIA_TYPE_AUDIO;
456  /* 16 bit form will be handled as AV_CODEC_ID_PCM_S16BE */
457  codec_id = AV_CODEC_ID_PCM_DVD;
458  } else if (startcode >= 0xb0 && startcode <= 0xbf) {
459  type = AVMEDIA_TYPE_AUDIO;
460  codec_id = AV_CODEC_ID_TRUEHD;
461  } else if (startcode >= 0xc0 && startcode <= 0xcf) {
462  /* Used for both AC-3 and E-AC-3 in EVOB files */
463  type = AVMEDIA_TYPE_AUDIO;
464  codec_id = AV_CODEC_ID_AC3;
465  } else if (startcode >= 0x20 && startcode <= 0x3f) {
466  type = AVMEDIA_TYPE_SUBTITLE;
467  codec_id = AV_CODEC_ID_DVD_SUBTITLE;
468  } else if (startcode >= 0xfd55 && startcode <= 0xfd5f) {
469  type = AVMEDIA_TYPE_VIDEO;
470  codec_id = AV_CODEC_ID_VC1;
471  } else if (startcode == 0x1bd) {
472  // check dvd audio substream type
473  type = AVMEDIA_TYPE_AUDIO;
474  switch(dvdaudio_substream_type & 0xe0) {
475  case 0xa0: codec_id = AV_CODEC_ID_PCM_DVD;
476  break;
477  case 0x80: if((dvdaudio_substream_type & 0xf8) == 0x88)
478  codec_id = AV_CODEC_ID_DTS;
479  else codec_id = AV_CODEC_ID_AC3;
480  break;
481  default: av_log(s, AV_LOG_ERROR, "Unknown 0x1bd sub-stream\n");
482  goto skip;
483  }
484  } else {
485  skip:
486  /* skip packet */
487  avio_skip(s->pb, len);
488  goto redo;
489  }
490  /* no stream found: add a new stream */
491  st = avformat_new_stream(s, NULL);
492  if (!st)
493  goto skip;
494  st->id = startcode;
495  st->codec->codec_type = type;
496  st->codec->codec_id = codec_id;
497  if (codec_id != AV_CODEC_ID_PCM_S16BE)
499  found:
500  if(st->discard >= AVDISCARD_ALL)
501  goto skip;
502  if ((startcode >= 0xa0 && startcode <= 0xaf) ||
503  (startcode == 0x1bd && ((dvdaudio_substream_type & 0xe0) == 0xa0))) {
504  int b1, freq;
505 
506  /* for LPCM, we just skip the header and consider it is raw
507  audio data */
508  if (len <= 3)
509  goto skip;
510  avio_r8(s->pb); /* emphasis (1), muse(1), reserved(1), frame number(5) */
511  b1 = avio_r8(s->pb); /* quant (2), freq(2), reserved(1), channels(3) */
512  avio_r8(s->pb); /* dynamic range control (0x80 = off) */
513  len -= 3;
514  freq = (b1 >> 4) & 3;
515  st->codec->sample_rate = lpcm_freq_tab[freq];
516  st->codec->channels = 1 + (b1 & 7);
517  st->codec->bits_per_coded_sample = 16 + ((b1 >> 6) & 3) * 4;
518  st->codec->bit_rate = st->codec->channels *
519  st->codec->sample_rate *
521  if (st->codec->bits_per_coded_sample == 16)
523  else if (st->codec->bits_per_coded_sample == 28)
524  return AVERROR(EINVAL);
525  }
526  ret = av_get_packet(s->pb, pkt, len);
527  pkt->pts = pts;
528  pkt->dts = dts;
529  pkt->pos = dummy_pos;
530  pkt->stream_index = st->index;
531  av_dlog(s, "%d: pts=%0.3f dts=%0.3f size=%d\n",
532  pkt->stream_index, pkt->pts / 90000.0, pkt->dts / 90000.0,
533  pkt->size);
534 
535  return (ret < 0) ? ret : 0;
536 }
537 
538 static int64_t mpegps_read_dts(AVFormatContext *s, int stream_index,
539  int64_t *ppos, int64_t pos_limit)
540 {
541  int len, startcode;
542  int64_t pos, pts, dts;
543 
544  pos = *ppos;
545  if (avio_seek(s->pb, pos, SEEK_SET) < 0)
546  return AV_NOPTS_VALUE;
547 
548  for(;;) {
549  len = mpegps_read_pes_header(s, &pos, &startcode, &pts, &dts);
550  if (len < 0) {
551  av_dlog(s, "none (ret=%d)\n", len);
552  return AV_NOPTS_VALUE;
553  }
554  if (startcode == s->streams[stream_index]->id &&
555  dts != AV_NOPTS_VALUE) {
556  break;
557  }
558  avio_skip(s->pb, len);
559  }
560  av_dlog(s, "pos=0x%"PRIx64" dts=0x%"PRIx64" %0.3f\n",
561  pos, dts, dts / 90000.0);
562  *ppos = pos;
563  return dts;
564 }
565 
567  .name = "mpeg",
568  .long_name = NULL_IF_CONFIG_SMALL("MPEG-PS (MPEG-2 Program Stream)"),
569  .priv_data_size = sizeof(MpegDemuxContext),
573  .read_timestamp = mpegps_read_dts,
575 };