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 //av_log(NULL, AV_LOG_ERROR, "%d %d %d %d %d %d len:%d\n", sys, priv1, pspack,vid, audio, invalid, p->buf_size);
88  if(sys>invalid && sys*9 <= pspack*10)
89  return pspack > 2 ? AVPROBE_SCORE_MAX/2+2 : AVPROBE_SCORE_MAX/4; // +1 for .mpg
90  if(pspack > invalid && (priv1+vid+audio)*10 >= pspack*9)
91  return pspack > 2 ? AVPROBE_SCORE_MAX/2+2 : AVPROBE_SCORE_MAX/4; // +1 for .mpg
92  if((!!vid ^ !!audio) && (audio > 4 || vid > 1) && !sys && !pspack && p->buf_size>2048 && vid + audio > invalid) /* PES stream */
93  return (audio > 12 || vid > 3) ? AVPROBE_SCORE_MAX/2+2 : AVPROBE_SCORE_MAX/4;
94 
95  //02-Penguin.flac has sys:0 priv1:0 pspack:0 vid:0 audio:1
96  //mp3_misidentified_2.mp3 has sys:0 priv1:0 pspack:0 vid:0 audio:6
97  return score;
98 }
99 
100 
101 typedef struct MpegDemuxContext {
102  int32_t header_state;
103  unsigned char psm_es_type[256];
104  int sofdec;
106 
108  AVFormatParameters *ap)
109 {
110  MpegDemuxContext *m = s->priv_data;
111  const char *sofdec = "Sofdec";
112  int v, i = 0;
113 
114  m->header_state = 0xff;
116 
117  m->sofdec = -1;
118  do {
119  v = avio_r8(s->pb);
120  m->header_state = m->header_state << 8 | v;
121  m->sofdec++;
122  } while (v == sofdec[i] && i++ < 6);
123 
124  m->sofdec = (m->sofdec == 6) ? 1 : 0;
125 
126  /* no need to do more */
127  return 0;
128 }
129 
130 static int64_t get_pts(AVIOContext *pb, int c)
131 {
132  uint8_t buf[5];
133 
134  buf[0] = c<0 ? avio_r8(pb) : c;
135  avio_read(pb, buf+1, 4);
136 
137  return ff_parse_pes_pts(buf);
138 }
139 
140 static int find_next_start_code(AVIOContext *pb, int *size_ptr,
141  int32_t *header_state)
142 {
143  unsigned int state, v;
144  int val, n;
145 
146  state = *header_state;
147  n = *size_ptr;
148  while (n > 0) {
149  if (pb->eof_reached)
150  break;
151  v = avio_r8(pb);
152  n--;
153  if (state == 0x000001) {
154  state = ((state << 8) | v) & 0xffffff;
155  val = state;
156  goto found;
157  }
158  state = ((state << 8) | v) & 0xffffff;
159  }
160  val = -1;
161  found:
162  *header_state = state;
163  *size_ptr = n;
164  return val;
165 }
166 
167 #if 0 /* unused, remove? */
168 /* XXX: optimize */
169 static int find_prev_start_code(AVIOContext *pb, int *size_ptr)
170 {
171  int64_t pos, pos_start;
172  int max_size, start_code;
173 
174  max_size = *size_ptr;
175  pos_start = avio_tell(pb);
176 
177  /* in order to go faster, we fill the buffer */
178  pos = pos_start - 16386;
179  if (pos < 0)
180  pos = 0;
181  avio_seek(pb, pos, SEEK_SET);
182  avio_r8(pb);
183 
184  pos = pos_start;
185  for(;;) {
186  pos--;
187  if (pos < 0 || (pos_start - pos) >= max_size) {
188  start_code = -1;
189  goto the_end;
190  }
191  avio_seek(pb, pos, SEEK_SET);
192  start_code = avio_rb32(pb);
193  if ((start_code & 0xffffff00) == 0x100)
194  break;
195  }
196  the_end:
197  *size_ptr = pos_start - pos;
198  return start_code;
199 }
200 #endif
201 
209 {
210  int psm_length, ps_info_length, es_map_length;
211 
212  psm_length = avio_rb16(pb);
213  avio_r8(pb);
214  avio_r8(pb);
215  ps_info_length = avio_rb16(pb);
216 
217  /* skip program_stream_info */
218  avio_skip(pb, ps_info_length);
219  es_map_length = avio_rb16(pb);
220 
221  /* at least one es available? */
222  while (es_map_length >= 4){
223  unsigned char type = avio_r8(pb);
224  unsigned char es_id = avio_r8(pb);
225  uint16_t es_info_length = avio_rb16(pb);
226  /* remember mapping from stream id to stream type */
227  m->psm_es_type[es_id] = type;
228  /* skip program_stream_info */
229  avio_skip(pb, es_info_length);
230  es_map_length -= 4 + es_info_length;
231  }
232  avio_rb32(pb); /* crc32 */
233  return 2 + psm_length;
234 }
235 
236 /* read the next PES header. Return its position in ppos
237  (if not NULL), and its start code, pts and dts.
238  */
240  int64_t *ppos, int *pstart_code,
241  int64_t *ppts, int64_t *pdts)
242 {
243  MpegDemuxContext *m = s->priv_data;
244  int len, size, startcode, c, flags, header_len;
245  int pes_ext, ext2_len, id_ext, skip;
246  int64_t pts, dts;
247  int64_t last_sync= avio_tell(s->pb);
248 
249  error_redo:
250  avio_seek(s->pb, last_sync, SEEK_SET);
251  redo:
252  /* next start code (should be immediately after) */
253  m->header_state = 0xff;
254  size = MAX_SYNC_SIZE;
255  startcode = find_next_start_code(s->pb, &size, &m->header_state);
256  last_sync = avio_tell(s->pb);
257  //printf("startcode=%x pos=0x%"PRIx64"\n", startcode, avio_tell(s->pb));
258  if (startcode < 0){
259  if(s->pb->eof_reached)
260  return AVERROR_EOF;
261  //FIXME we should remember header_state
262  return AVERROR(EAGAIN);
263  }
264 
265  if (startcode == PACK_START_CODE)
266  goto redo;
267  if (startcode == SYSTEM_HEADER_START_CODE)
268  goto redo;
269  if (startcode == PADDING_STREAM) {
270  avio_skip(s->pb, avio_rb16(s->pb));
271  goto redo;
272  }
273  if (startcode == PRIVATE_STREAM_2) {
274  len = avio_rb16(s->pb);
275  if (!m->sofdec) {
276  while (len-- >= 6) {
277  if (avio_r8(s->pb) == 'S') {
278  uint8_t buf[5];
279  avio_read(s->pb, buf, sizeof(buf));
280  m->sofdec = !memcmp(buf, "ofdec", 5);
281  len -= sizeof(buf);
282  break;
283  }
284  }
285  m->sofdec -= !m->sofdec;
286  }
287  avio_skip(s->pb, len);
288  goto redo;
289  }
290  if (startcode == PROGRAM_STREAM_MAP) {
291  mpegps_psm_parse(m, s->pb);
292  goto redo;
293  }
294 
295  /* find matching stream */
296  if (!((startcode >= 0x1c0 && startcode <= 0x1df) ||
297  (startcode >= 0x1e0 && startcode <= 0x1ef) ||
298  (startcode == 0x1bd) || (startcode == 0x1fd)))
299  goto redo;
300  if (ppos) {
301  *ppos = avio_tell(s->pb) - 4;
302  }
303  len = avio_rb16(s->pb);
304  pts =
305  dts = AV_NOPTS_VALUE;
306  /* stuffing */
307  for(;;) {
308  if (len < 1)
309  goto error_redo;
310  c = avio_r8(s->pb);
311  len--;
312  /* XXX: for mpeg1, should test only bit 7 */
313  if (c != 0xff)
314  break;
315  }
316  if ((c & 0xc0) == 0x40) {
317  /* buffer scale & size */
318  avio_r8(s->pb);
319  c = avio_r8(s->pb);
320  len -= 2;
321  }
322  if ((c & 0xe0) == 0x20) {
323  dts = pts = get_pts(s->pb, c);
324  len -= 4;
325  if (c & 0x10){
326  dts = get_pts(s->pb, -1);
327  len -= 5;
328  }
329  } else if ((c & 0xc0) == 0x80) {
330  /* mpeg 2 PES */
331 #if 0 /* some streams have this field set for no apparent reason */
332  if ((c & 0x30) != 0) {
333  /* Encrypted multiplex not handled */
334  goto redo;
335  }
336 #endif
337  flags = avio_r8(s->pb);
338  header_len = avio_r8(s->pb);
339  len -= 2;
340  if (header_len > len)
341  goto error_redo;
342  len -= header_len;
343  if (flags & 0x80) {
344  dts = pts = get_pts(s->pb, -1);
345  header_len -= 5;
346  if (flags & 0x40) {
347  dts = get_pts(s->pb, -1);
348  header_len -= 5;
349  }
350  }
351  if (flags & 0x3f && header_len == 0){
352  flags &= 0xC0;
353  av_log(s, AV_LOG_WARNING, "Further flags set but no bytes left\n");
354  }
355  if (flags & 0x01) { /* PES extension */
356  pes_ext = avio_r8(s->pb);
357  header_len--;
358  /* Skip PES private data, program packet sequence counter and P-STD buffer */
359  skip = (pes_ext >> 4) & 0xb;
360  skip += skip & 0x9;
361  if (pes_ext & 0x40 || skip > header_len){
362  av_log(s, AV_LOG_WARNING, "pes_ext %X is invalid\n", pes_ext);
363  pes_ext=skip=0;
364  }
365  avio_skip(s->pb, skip);
366  header_len -= skip;
367 
368  if (pes_ext & 0x01) { /* PES extension 2 */
369  ext2_len = avio_r8(s->pb);
370  header_len--;
371  if ((ext2_len & 0x7f) > 0) {
372  id_ext = avio_r8(s->pb);
373  if ((id_ext & 0x80) == 0)
374  startcode = ((startcode & 0xff) << 8) | id_ext;
375  header_len--;
376  }
377  }
378  }
379  if(header_len < 0)
380  goto error_redo;
381  avio_skip(s->pb, header_len);
382  }
383  else if( c!= 0xf )
384  goto redo;
385 
386  if (startcode == PRIVATE_STREAM_1 && !m->psm_es_type[startcode & 0xff]) {
387  startcode = avio_r8(s->pb);
388  len--;
389  if (startcode >= 0x80 && startcode <= 0xcf) {
390  /* audio: skip header */
391  avio_r8(s->pb);
392  avio_r8(s->pb);
393  avio_r8(s->pb);
394  len -= 3;
395  if (startcode >= 0xb0 && startcode <= 0xbf) {
396  /* MLP/TrueHD audio has a 4-byte header */
397  avio_r8(s->pb);
398  len--;
399  }
400  }
401  }
402  if(len<0)
403  goto error_redo;
404  if(dts != AV_NOPTS_VALUE && ppos){
405  int i;
406  for(i=0; i<s->nb_streams; i++){
407  if(startcode == s->streams[i]->id &&
408  s->pb->seekable /* index useless on streams anyway */) {
409  ff_reduce_index(s, i);
410  av_add_index_entry(s->streams[i], *ppos, dts, 0, 0, AVINDEX_KEYFRAME /* FIXME keyframe? */);
411  }
412  }
413  }
414 
415  *pstart_code = startcode;
416  *ppts = pts;
417  *pdts = dts;
418  return len;
419 }
420 
422  AVPacket *pkt)
423 {
424  MpegDemuxContext *m = s->priv_data;
425  AVStream *st;
426  int len, startcode, i, es_type, ret;
428  enum AVMediaType type;
429  int64_t pts, dts, dummy_pos; //dummy_pos is needed for the index building to work
430  uint8_t av_uninit(dvdaudio_substream_type);
431 
432  redo:
433  len = mpegps_read_pes_header(s, &dummy_pos, &startcode, &pts, &dts);
434  if (len < 0)
435  return len;
436 
437  if(startcode == 0x1bd) {
438  dvdaudio_substream_type = avio_r8(s->pb);
439  avio_skip(s->pb, 3);
440  len -= 4;
441  }
442 
443  /* now find stream */
444  for(i=0;i<s->nb_streams;i++) {
445  st = s->streams[i];
446  if (st->id == startcode)
447  goto found;
448  }
449 
450  es_type = m->psm_es_type[startcode & 0xff];
451  if(es_type > 0 && es_type != STREAM_TYPE_PRIVATE_DATA){
452  if(es_type == STREAM_TYPE_VIDEO_MPEG1){
453  codec_id = CODEC_ID_MPEG2VIDEO;
454  type = AVMEDIA_TYPE_VIDEO;
455  } else if(es_type == STREAM_TYPE_VIDEO_MPEG2){
456  codec_id = CODEC_ID_MPEG2VIDEO;
457  type = AVMEDIA_TYPE_VIDEO;
458  } else if(es_type == STREAM_TYPE_AUDIO_MPEG1 ||
459  es_type == STREAM_TYPE_AUDIO_MPEG2){
460  codec_id = CODEC_ID_MP3;
461  type = AVMEDIA_TYPE_AUDIO;
462  } else if(es_type == STREAM_TYPE_AUDIO_AAC){
463  codec_id = CODEC_ID_AAC;
464  type = AVMEDIA_TYPE_AUDIO;
465  } else if(es_type == STREAM_TYPE_VIDEO_MPEG4){
466  codec_id = CODEC_ID_MPEG4;
467  type = AVMEDIA_TYPE_VIDEO;
468  } else if(es_type == STREAM_TYPE_VIDEO_H264){
469  codec_id = CODEC_ID_H264;
470  type = AVMEDIA_TYPE_VIDEO;
471  } else if(es_type == STREAM_TYPE_AUDIO_AC3){
472  codec_id = CODEC_ID_AC3;
473  type = AVMEDIA_TYPE_AUDIO;
474  } else {
475  goto skip;
476  }
477  } else if (startcode >= 0x1e0 && startcode <= 0x1ef) {
478  static const unsigned char avs_seqh[4] = { 0, 0, 1, 0xb0 };
479  unsigned char buf[8];
480  avio_read(s->pb, buf, 8);
481  avio_seek(s->pb, -8, SEEK_CUR);
482  if(!memcmp(buf, avs_seqh, 4) && (buf[6] != 0 || buf[7] != 1))
483  codec_id = CODEC_ID_CAVS;
484  else
485  codec_id = CODEC_ID_PROBE;
486  type = AVMEDIA_TYPE_VIDEO;
487  } else if (startcode >= 0x1c0 && startcode <= 0x1df) {
488  type = AVMEDIA_TYPE_AUDIO;
489  codec_id = m->sofdec > 0 ? CODEC_ID_ADPCM_ADX : CODEC_ID_MP2;
490  } else if (startcode >= 0x80 && startcode <= 0x87) {
491  type = AVMEDIA_TYPE_AUDIO;
492  codec_id = CODEC_ID_AC3;
493  } else if ( ( startcode >= 0x88 && startcode <= 0x8f)
494  ||( startcode >= 0x98 && startcode <= 0x9f)) {
495  /* 0x90 - 0x97 is reserved for SDDS in DVD specs */
496  type = AVMEDIA_TYPE_AUDIO;
497  codec_id = CODEC_ID_DTS;
498  } else if (startcode >= 0xa0 && startcode <= 0xaf) {
499  type = AVMEDIA_TYPE_AUDIO;
500  /* 16 bit form will be handled as CODEC_ID_PCM_S16BE */
501  codec_id = CODEC_ID_PCM_DVD;
502  } else if (startcode >= 0xb0 && startcode <= 0xbf) {
503  type = AVMEDIA_TYPE_AUDIO;
504  codec_id = CODEC_ID_TRUEHD;
505  } else if (startcode >= 0xc0 && startcode <= 0xcf) {
506  /* Used for both AC-3 and E-AC-3 in EVOB files */
507  type = AVMEDIA_TYPE_AUDIO;
508  codec_id = CODEC_ID_AC3;
509  } else if (startcode >= 0x20 && startcode <= 0x3f) {
510  type = AVMEDIA_TYPE_SUBTITLE;
511  codec_id = CODEC_ID_DVD_SUBTITLE;
512  } else if (startcode >= 0xfd55 && startcode <= 0xfd5f) {
513  type = AVMEDIA_TYPE_VIDEO;
514  codec_id = CODEC_ID_VC1;
515  } else if (startcode == 0x1bd) {
516  // check dvd audio substream type
517  type = AVMEDIA_TYPE_AUDIO;
518  switch(dvdaudio_substream_type & 0xe0) {
519  case 0xa0: codec_id = CODEC_ID_PCM_DVD;
520  break;
521  case 0x80: if((dvdaudio_substream_type & 0xf8) == 0x88)
522  codec_id = CODEC_ID_DTS;
523  else codec_id = CODEC_ID_AC3;
524  break;
525  default: av_log(s, AV_LOG_ERROR, "Unknown 0x1bd sub-stream\n");
526  goto skip;
527  }
528  } else {
529  skip:
530  /* skip packet */
531  avio_skip(s->pb, len);
532  goto redo;
533  }
534  /* no stream found: add a new stream */
535  st = avformat_new_stream(s, NULL);
536  if (!st)
537  goto skip;
538  st->id = startcode;
539  st->codec->codec_type = type;
540  st->codec->codec_id = codec_id;
541  if (codec_id != CODEC_ID_PCM_S16BE)
543  found:
544  if(st->discard >= AVDISCARD_ALL)
545  goto skip;
546  if ((startcode >= 0xa0 && startcode <= 0xaf) ||
547  (startcode == 0x1bd && ((dvdaudio_substream_type & 0xe0) == 0xa0))) {
548  int b1, freq;
549 
550  /* for LPCM, we just skip the header and consider it is raw
551  audio data */
552  if (len <= 3)
553  goto skip;
554  avio_r8(s->pb); /* emphasis (1), muse(1), reserved(1), frame number(5) */
555  b1 = avio_r8(s->pb); /* quant (2), freq(2), reserved(1), channels(3) */
556  avio_r8(s->pb); /* dynamic range control (0x80 = off) */
557  len -= 3;
558  freq = (b1 >> 4) & 3;
559  st->codec->sample_rate = lpcm_freq_tab[freq];
560  st->codec->channels = 1 + (b1 & 7);
561  st->codec->bits_per_coded_sample = 16 + ((b1 >> 6) & 3) * 4;
562  st->codec->bit_rate = st->codec->channels *
563  st->codec->sample_rate *
565  if (st->codec->bits_per_coded_sample == 16)
567  else if (st->codec->bits_per_coded_sample == 28)
568  return AVERROR(EINVAL);
569  }
570  ret = av_get_packet(s->pb, pkt, len);
571  pkt->pts = pts;
572  pkt->dts = dts;
573  pkt->pos = dummy_pos;
574  pkt->stream_index = st->index;
575  av_dlog(s, "%d: pts=%0.3f dts=%0.3f size=%d\n",
576  pkt->stream_index, pkt->pts / 90000.0, pkt->dts / 90000.0,
577  pkt->size);
578 
579  return (ret < 0) ? ret : 0;
580 }
581 
582 static int64_t mpegps_read_dts(AVFormatContext *s, int stream_index,
583  int64_t *ppos, int64_t pos_limit)
584 {
585  int len, startcode;
586  int64_t pos, pts, dts;
587 
588  pos = *ppos;
589  if (avio_seek(s->pb, pos, SEEK_SET) < 0)
590  return AV_NOPTS_VALUE;
591 
592  for(;;) {
593  len = mpegps_read_pes_header(s, &pos, &startcode, &pts, &dts);
594  if (len < 0) {
595  av_dlog(s, "none (ret=%d)\n", len);
596  return AV_NOPTS_VALUE;
597  }
598  if (startcode == s->streams[stream_index]->id &&
599  dts != AV_NOPTS_VALUE) {
600  break;
601  }
602  avio_skip(s->pb, len);
603  }
604  av_dlog(s, "pos=0x%"PRIx64" dts=0x%"PRIx64" %0.3f\n",
605  pos, dts, dts / 90000.0);
606  *ppos = pos;
607  return dts;
608 }
609 
611  .name = "mpeg",
612  .long_name = NULL_IF_CONFIG_SMALL("MPEG-PS format"),
613  .priv_data_size = sizeof(MpegDemuxContext),
617  .read_timestamp = mpegps_read_dts,
619 };