libavformat/mpeg.c

   1 /*
   2  * MPEG1/2 demuxer
   3  * Copyright (c) 2000, 2001, 2002 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 "avformat.h"
  23 #include "mpeg.h"
  24
  25 //#define DEBUG_SEEK
  26
  27 #undef NDEBUG
  28 #include <assert.h>
  29
  30 /*********************************************/
  31 /* demux code */
  32
  33 #define MAX_SYNC_SIZE 100000
  34
  35 static int check_pes(uint8_t *p, uint8_t *end){
  36     int pes1;
  37     int pes2=      (p[3] & 0xC0) == 0x80
  38                 && (p[4] & 0xC0) != 0x40
  39                 &&((p[4] & 0xC0) == 0x00 || (p[4]&0xC0)>>2 == (p[6]&0xF0));
  40
  41     for(p+=3; p<end && *p == 0xFF; p++);
  42     if((*p&0xC0) == 0x40) p+=2;
  43     if((*p&0xF0) == 0x20){
  44         pes1= p[0]&p[2]&p[4]&1;
  45     }else if((*p&0xF0) == 0x30){
  46         pes1= p[0]&p[2]&p[4]&p[5]&p[7]&p[9]&1;
  47     }else
  48         pes1 = *p == 0x0F;
  49
  50     return pes1||pes2;
  51 }
  52
  53 static int mpegps_probe(AVProbeData *p)
  54 {
  55     uint32_t code= -1;
  56     int sys=0, pspack=0, priv1=0, vid=0, audio=0, invalid=0;
  57     int i;
  58     int score=0;
  59
  60     for(i=0; i<p->buf_size; i++){
  61         code = (code<<8) + p->buf[i];
  62         if ((code & 0xffffff00) == 0x100) {
  63             int pes= check_pes(p->buf+i, p->buf+p->buf_size);
  64
  65             if(code == SYSTEM_HEADER_START_CODE) sys++;
  66             else if(code == PRIVATE_STREAM_1)    priv1++;
  67             else if(code == PACK_START_CODE)     pspack++;
  68             else if((code & 0xf0) == VIDEO_ID &&  pes) vid++;
  69             else if((code & 0xe0) == AUDIO_ID &&  pes) audio++;
  70
  71             else if((code & 0xf0) == VIDEO_ID && !pes) invalid++;
  72             else if((code & 0xe0) == AUDIO_ID && !pes) invalid++;
  73         }
  74     }
  75
  76     if(vid+audio > invalid)     /* invalid VDR files nd short PES streams */
  77         score= AVPROBE_SCORE_MAX/4;
  78
  79 //av_log(NULL, AV_LOG_ERROR, "%d %d %d %d %d len:%d\n", sys, priv1, pspack,vid, audio, p->buf_size);
  80     if(sys>invalid && sys*9 <= pspack*10)
  81         return pspack > 2 ? AVPROBE_SCORE_MAX/2+2 : AVPROBE_SCORE_MAX/4; // +1 for .mpg
  82     if(priv1 + vid + audio > invalid && (priv1+vid+audio)*9 <= pspack*10)
  83         return pspack > 2 ? AVPROBE_SCORE_MAX/2+2 : AVPROBE_SCORE_MAX/4; // +1 for .mpg
  84     if((!!vid ^ !!audio) && (audio > 4 || vid > 1) && !sys && !pspack && p->buf_size>2048 && vid + audio > invalid) /* PES stream */
  85         return (audio > 12 || vid > 3) ? AVPROBE_SCORE_MAX/2+2 : AVPROBE_SCORE_MAX/4;
  86
  87     //02-Penguin.flac has sys:0 priv1:0 pspack:0 vid:0 audio:1
  88     //mp3_misidentified_2.mp3 has sys:0 priv1:0 pspack:0 vid:0 audio:6
  89     return score;
  90 }
  91
  92
  93 typedef struct MpegDemuxContext {
  94     int32_t header_state;
  95     unsigned char psm_es_type[256];
  96     int sofdec;
  97 } MpegDemuxContext;
  98
  99 static int mpegps_read_header(AVFormatContext *s,
 100                               AVFormatParameters *ap)
 101 {
 102     MpegDemuxContext *m = s->priv_data;
 103     const char *sofdec = "Sofdec";
 104     int v, i = 0;
 105
 106     m->header_state = 0xff;
 107     s->ctx_flags |= AVFMTCTX_NOHEADER;
 108
 109     m->sofdec = -1;
 110     do {
 111         v = get_byte(s->pb);
 112         m->header_state = m->header_state << 8 | v;
 113         m->sofdec++;
 114     } while (v == sofdec[i] && i++ < 6);
 115
 116     /* no need to do more */
 117     return 0;
 118 }
 119
 120 static int64_t get_pts(ByteIOContext *pb, int c)
 121 {
 122     uint8_t buf[5];
 123
 124     buf[0] = c<0 ? get_byte(pb) : c;
 125     get_buffer(pb, buf+1, 4);
 126
 127     return ff_parse_pes_pts(buf);
 128 }
 129
 130 static int find_next_start_code(ByteIOContext *pb, int *size_ptr,
 131                                 int32_t *header_state)
 132 {
 133     unsigned int state, v;
 134     int val, n;
 135
 136     state = *header_state;
 137     n = *size_ptr;
 138     while (n > 0) {
 139         if (url_feof(pb))
 140             break;
 141         v = get_byte(pb);
 142         n--;
 143         if (state == 0x000001) {
 144             state = ((state << 8) | v) & 0xffffff;
 145             val = state;
 146             goto found;
 147         }
 148         state = ((state << 8) | v) & 0xffffff;
 149     }
 150     val = -1;
 151  found:
 152     *header_state = state;
 153     *size_ptr = n;
 154     return val;
 155 }
 156
 157 #if 0 /* unused, remove? */
 158 /* XXX: optimize */
 159 static int find_prev_start_code(ByteIOContext *pb, int *size_ptr)
 160 {
 161     int64_t pos, pos_start;
 162     int max_size, start_code;
 163
 164     max_size = *size_ptr;
 165     pos_start = url_ftell(pb);
 166
 167     /* in order to go faster, we fill the buffer */
 168     pos = pos_start - 16386;
 169     if (pos < 0)
 170         pos = 0;
 171     url_fseek(pb, pos, SEEK_SET);
 172     get_byte(pb);
 173
 174     pos = pos_start;
 175     for(;;) {
 176         pos--;
 177         if (pos < 0 || (pos_start - pos) >= max_size) {
 178             start_code = -1;
 179             goto the_end;
 180         }
 181         url_fseek(pb, pos, SEEK_SET);
 182         start_code = get_be32(pb);
 183         if ((start_code & 0xffffff00) == 0x100)
 184             break;
 185     }
 186  the_end:
 187     *size_ptr = pos_start - pos;
 188     return start_code;
 189 }
 190 #endif
 191
 192 /**
 193  * Extracts stream types from a program stream map
 194  * According to ISO/IEC 13818-1 ('MPEG-2 Systems') table 2-35
 195  *
 196  * @return number of bytes occupied by PSM in the bitstream
 197  */
 198 static long mpegps_psm_parse(MpegDemuxContext *m, ByteIOContext *pb)
 199 {
 200     int psm_length, ps_info_length, es_map_length;
 201
 202     psm_length = get_be16(pb);
 203     get_byte(pb);
 204     get_byte(pb);
 205     ps_info_length = get_be16(pb);
 206
 207     /* skip program_stream_info */
 208     url_fskip(pb, ps_info_length);
 209     es_map_length = get_be16(pb);
 210
 211     /* at least one es available? */
 212     while (es_map_length >= 4){
 213         unsigned char type      = get_byte(pb);
 214         unsigned char es_id     = get_byte(pb);
 215         uint16_t es_info_length = get_be16(pb);
 216         /* remember mapping from stream id to stream type */
 217         m->psm_es_type[es_id] = type;
 218         /* skip program_stream_info */
 219         url_fskip(pb, es_info_length);
 220         es_map_length -= 4 + es_info_length;
 221     }
 222     get_be32(pb); /* crc32 */
 223     return 2 + psm_length;
 224 }
 225
 226 /* read the next PES header. Return its position in ppos
 227    (if not NULL), and its start code, pts and dts.
 228  */
 229 static int mpegps_read_pes_header(AVFormatContext *s,
 230                                   int64_t *ppos, int *pstart_code,
 231                                   int64_t *ppts, int64_t *pdts)
 232 {
 233     MpegDemuxContext *m = s->priv_data;
 234     int len, size, startcode, c, flags, header_len;
 235     int pes_ext, ext2_len, id_ext, skip;
 236     int64_t pts, dts;
 237     int64_t last_sync= url_ftell(s->pb);
 238
 239  error_redo:
 240         url_fseek(s->pb, last_sync, SEEK_SET);
 241  redo:
 242         /* next start code (should be immediately after) */
 243         m->header_state = 0xff;
 244         size = MAX_SYNC_SIZE;
 245         startcode = find_next_start_code(s->pb, &size, &m->header_state);
 246         last_sync = url_ftell(s->pb);
 247     //printf("startcode=%x pos=0x%"PRIx64"\n", startcode, url_ftell(s->pb));
 248     if (startcode < 0)
 249         return AVERROR(EIO);
 250     if (startcode == PACK_START_CODE)
 251         goto redo;
 252     if (startcode == SYSTEM_HEADER_START_CODE)
 253         goto redo;
 254     if (startcode == PADDING_STREAM) {
 255         url_fskip(s->pb, get_be16(s->pb));
 256         goto redo;
 257     }
 258     if (startcode == PRIVATE_STREAM_2) {
 259         len = get_be16(s->pb);
 260         if (!m->sofdec) {
 261             while (len-- >= 6) {
 262                 if (get_byte(s->pb) == 'S') {
 263                     uint8_t buf[5];
 264                     get_buffer(s->pb, buf, sizeof(buf));
 265                     m->sofdec = !memcmp(buf, "ofdec", 5);
 266                     len -= sizeof(buf);
 267                     break;
 268                 }
 269             }
 270             m->sofdec -= !m->sofdec;
 271         }
 272         url_fskip(s->pb, len);
 273         goto redo;
 274     }
 275     if (startcode == PROGRAM_STREAM_MAP) {
 276         mpegps_psm_parse(m, s->pb);
 277         goto redo;
 278     }
 279
 280     /* find matching stream */
 281     if (!((startcode >= 0x1c0 && startcode <= 0x1df) ||
 282           (startcode >= 0x1e0 && startcode <= 0x1ef) ||
 283           (startcode == 0x1bd) || (startcode == 0x1fd)))
 284         goto redo;
 285     if (ppos) {
 286         *ppos = url_ftell(s->pb) - 4;
 287     }
 288     len = get_be16(s->pb);
 289     pts =
 290     dts = AV_NOPTS_VALUE;
 291     /* stuffing */
 292     for(;;) {
 293         if (len < 1)
 294             goto error_redo;
 295         c = get_byte(s->pb);
 296         len--;
 297         /* XXX: for mpeg1, should test only bit 7 */
 298         if (c != 0xff)
 299             break;
 300     }
 301     if ((c & 0xc0) == 0x40) {
 302         /* buffer scale & size */
 303         get_byte(s->pb);
 304         c = get_byte(s->pb);
 305         len -= 2;
 306     }
 307     if ((c & 0xe0) == 0x20) {
 308         dts = pts = get_pts(s->pb, c);
 309         len -= 4;
 310         if (c & 0x10){
 311             dts = get_pts(s->pb, -1);
 312             len -= 5;
 313         }
 314     } else if ((c & 0xc0) == 0x80) {
 315         /* mpeg 2 PES */
 316 #if 0 /* some streams have this field set for no apparent reason */
 317         if ((c & 0x30) != 0) {
 318             /* Encrypted multiplex not handled */
 319             goto redo;
 320         }
 321 #endif
 322         flags = get_byte(s->pb);
 323         header_len = get_byte(s->pb);
 324         len -= 2;
 325         if (header_len > len)
 326             goto error_redo;
 327         len -= header_len;
 328         if (flags & 0x80) {
 329             dts = pts = get_pts(s->pb, -1);
 330             header_len -= 5;
 331             if (flags & 0x40) {
 332                 dts = get_pts(s->pb, -1);
 333                 header_len -= 5;
 334             }
 335         }
 336         if (flags & 0x3f && header_len == 0){
 337             flags &= 0xC0;
 338             av_log(s, AV_LOG_WARNING, "Further flags set but no bytes left\n");
 339         }
 340         if (flags & 0x01) { /* PES extension */
 341             pes_ext = get_byte(s->pb);
 342             header_len--;
 343             /* Skip PES private data, program packet sequence counter and P-STD buffer */
 344             skip = (pes_ext >> 4) & 0xb;
 345             skip += skip & 0x9;
 346             if (pes_ext & 0x40 || skip > header_len){
 347                 av_log(s, AV_LOG_WARNING, "pes_ext %X is invalid\n", pes_ext);
 348                 pes_ext=skip=0;
 349             }
 350             url_fskip(s->pb, skip);
 351             header_len -= skip;
 352
 353             if (pes_ext & 0x01) { /* PES extension 2 */
 354                 ext2_len = get_byte(s->pb);
 355                 header_len--;
 356                 if ((ext2_len & 0x7f) > 0) {
 357                     id_ext = get_byte(s->pb);
 358                     if ((id_ext & 0x80) == 0)
 359                         startcode = ((startcode & 0xff) << 8) | id_ext;
 360                     header_len--;
 361                 }
 362             }
 363         }
 364         if(header_len < 0)
 365             goto error_redo;
 366         url_fskip(s->pb, header_len);
 367     }
 368     else if( c!= 0xf )
 369         goto redo;
 370
 371     if (startcode == PRIVATE_STREAM_1 && !m->psm_es_type[startcode & 0xff]) {
 372         startcode = get_byte(s->pb);
 373         len--;
 374         if (startcode >= 0x80 && startcode <= 0xcf) {
 375             /* audio: skip header */
 376             get_byte(s->pb);
 377             get_byte(s->pb);
 378             get_byte(s->pb);
 379             len -= 3;
 380             if (startcode >= 0xb0 && startcode <= 0xbf) {
 381                 /* MLP/TrueHD audio has a 4-byte header */
 382                 get_byte(s->pb);
 383                 len--;
 384             }
 385         }
 386     }
 387     if(len<0)
 388         goto error_redo;
 389     if(dts != AV_NOPTS_VALUE && ppos){
 390         int i;
 391         for(i=0; i<s->nb_streams; i++){
 392             if(startcode == s->streams[i]->id &&
 393                !url_is_streamed(s->pb) /* index useless on streams anyway */) {
 394                 ff_reduce_index(s, i);
 395                 av_add_index_entry(s->streams[i], *ppos, dts, 0, 0, AVINDEX_KEYFRAME /* FIXME keyframe? */);
 396             }
 397         }
 398     }
 399
 400     *pstart_code = startcode;
 401     *ppts = pts;
 402     *pdts = dts;
 403     return len;
 404 }
 405
 406 static int mpegps_read_packet(AVFormatContext *s,
 407                               AVPacket *pkt)
 408 {
 409     MpegDemuxContext *m = s->priv_data;
 410     AVStream *st;
 411     int len, startcode, i, es_type;
 412     enum CodecID codec_id = CODEC_ID_NONE;
 413     enum CodecType type;
 414     int64_t pts, dts, dummy_pos; //dummy_pos is needed for the index building to work
 415     uint8_t av_uninit(dvdaudio_substream_type);
 416
 417  redo:
 418     len = mpegps_read_pes_header(s, &dummy_pos, &startcode, &pts, &dts);
 419     if (len < 0)
 420         return len;
 421
 422     if(startcode == 0x1bd) {
 423         dvdaudio_substream_type = get_byte(s->pb);
 424         url_fskip(s->pb, 3);
 425         len -= 4;
 426     }
 427
 428     /* now find stream */
 429     for(i=0;i<s->nb_streams;i++) {
 430         st = s->streams[i];
 431         if (st->id == startcode)
 432             goto found;
 433     }
 434
 435     es_type = m->psm_es_type[startcode & 0xff];
 436     if(es_type > 0 && es_type != STREAM_TYPE_PRIVATE_DATA){
 437         if(es_type == STREAM_TYPE_VIDEO_MPEG1){
 438             codec_id = CODEC_ID_MPEG2VIDEO;
 439             type = CODEC_TYPE_VIDEO;
 440         } else if(es_type == STREAM_TYPE_VIDEO_MPEG2){
 441             codec_id = CODEC_ID_MPEG2VIDEO;
 442             type = CODEC_TYPE_VIDEO;
 443         } else if(es_type == STREAM_TYPE_AUDIO_MPEG1 ||
 444                   es_type == STREAM_TYPE_AUDIO_MPEG2){
 445             codec_id = CODEC_ID_MP3;
 446             type = CODEC_TYPE_AUDIO;
 447         } else if(es_type == STREAM_TYPE_AUDIO_AAC){
 448             codec_id = CODEC_ID_AAC;
 449             type = CODEC_TYPE_AUDIO;
 450         } else if(es_type == STREAM_TYPE_VIDEO_MPEG4){
 451             codec_id = CODEC_ID_MPEG4;
 452             type = CODEC_TYPE_VIDEO;
 453         } else if(es_type == STREAM_TYPE_VIDEO_H264){
 454             codec_id = CODEC_ID_H264;
 455             type = CODEC_TYPE_VIDEO;
 456         } else if(es_type == STREAM_TYPE_AUDIO_AC3){
 457             codec_id = CODEC_ID_AC3;
 458             type = CODEC_TYPE_AUDIO;
 459         } else {
 460             goto skip;
 461         }
 462     } else if (startcode >= 0x1e0 && startcode <= 0x1ef) {
 463         static const unsigned char avs_seqh[4] = { 0, 0, 1, 0xb0 };
 464         unsigned char buf[8];
 465         get_buffer(s->pb, buf, 8);
 466         url_fseek(s->pb, -8, SEEK_CUR);
 467         if(!memcmp(buf, avs_seqh, 4) && (buf[6] != 0 || buf[7] != 1))
 468             codec_id = CODEC_ID_CAVS;
 469         else
 470             codec_id = CODEC_ID_PROBE;
 471         type = CODEC_TYPE_VIDEO;
 472     } else if (startcode >= 0x1c0 && startcode <= 0x1df) {
 473         type = CODEC_TYPE_AUDIO;
 474         codec_id = m->sofdec > 0 ? CODEC_ID_ADPCM_ADX : CODEC_ID_MP2;
 475     } else if (startcode >= 0x80 && startcode <= 0x87) {
 476         type = CODEC_TYPE_AUDIO;
 477         codec_id = CODEC_ID_AC3;
 478     } else if (  ( startcode >= 0x88 && startcode <= 0x8f)
 479                ||( startcode >= 0x98 && startcode <= 0x9f)) {
 480         /* 0x90 - 0x97 is reserved for SDDS in DVD specs */
 481         type = CODEC_TYPE_AUDIO;
 482         codec_id = CODEC_ID_DTS;
 483     } else if (startcode >= 0xa0 && startcode <= 0xaf) {
 484         type = CODEC_TYPE_AUDIO;
 485         /* 16 bit form will be handled as CODEC_ID_PCM_S16BE */
 486         codec_id = CODEC_ID_PCM_DVD;
 487     } else if (startcode >= 0xb0 && startcode <= 0xbf) {
 488         type = CODEC_TYPE_AUDIO;
 489         codec_id = CODEC_ID_TRUEHD;
 490     } else if (startcode >= 0xc0 && startcode <= 0xcf) {
 491         /* Used for both AC-3 and E-AC-3 in EVOB files */
 492         type = CODEC_TYPE_AUDIO;
 493         codec_id = CODEC_ID_AC3;
 494     } else if (startcode >= 0x20 && startcode <= 0x3f) {
 495         type = CODEC_TYPE_SUBTITLE;
 496         codec_id = CODEC_ID_DVD_SUBTITLE;
 497     } else if (startcode >= 0xfd55 && startcode <= 0xfd5f) {
 498         type = CODEC_TYPE_VIDEO;
 499         codec_id = CODEC_ID_VC1;
 500     } else if (startcode == 0x1bd) {
 501         // check dvd audio substream type
 502         type = CODEC_TYPE_AUDIO;
 503         switch(dvdaudio_substream_type & 0xe0) {
 504         case 0xa0:  codec_id = CODEC_ID_PCM_DVD;
 505                     break;
 506         case 0x80:  if((dvdaudio_substream_type & 0xf8) == 0x88)
 507                          codec_id = CODEC_ID_DTS;
 508                     else codec_id = CODEC_ID_AC3;
 509                     break;
 510         default:    av_log(s, AV_LOG_ERROR, "Unknown 0x1bd sub-stream\n");
 511                     goto skip;
 512         }
 513     } else {
 514     skip:
 515         /* skip packet */
 516         url_fskip(s->pb, len);
 517         goto redo;
 518     }
 519     /* no stream found: add a new stream */
 520     st = av_new_stream(s, startcode);
 521     if (!st)
 522         goto skip;
 523     st->codec->codec_type = type;
 524     st->codec->codec_id = codec_id;
 525     if (codec_id != CODEC_ID_PCM_S16BE)
 526         st->need_parsing = AVSTREAM_PARSE_FULL;
 527  found:
 528     if(st->discard >= AVDISCARD_ALL)
 529         goto skip;
 530     if ((startcode >= 0xa0 && startcode <= 0xaf) ||
 531         (startcode == 0x1bd && ((dvdaudio_substream_type & 0xe0) == 0xa0))) {
 532         int b1, freq;
 533
 534         /* for LPCM, we just skip the header and consider it is raw
 535            audio data */
 536         if (len <= 3)
 537             goto skip;
 538         get_byte(s->pb); /* emphasis (1), muse(1), reserved(1), frame number(5) */
 539         b1 = get_byte(s->pb); /* quant (2), freq(2), reserved(1), channels(3) */
 540         get_byte(s->pb); /* dynamic range control (0x80 = off) */
 541         len -= 3;
 542         freq = (b1 >> 4) & 3;
 543         st->codec->sample_rate = lpcm_freq_tab[freq];
 544         st->codec->channels = 1 + (b1 & 7);
 545         st->codec->bits_per_coded_sample = 16 + ((b1 >> 6) & 3) * 4;
 546         st->codec->bit_rate = st->codec->channels *
 547                               st->codec->sample_rate *
 548                               st->codec->bits_per_coded_sample;
 549         if (st->codec->bits_per_coded_sample == 16)
 550             st->codec->codec_id = CODEC_ID_PCM_S16BE;
 551         else if (st->codec->bits_per_coded_sample == 28)
 552             return AVERROR(EINVAL);
 553     }
 554     av_new_packet(pkt, len);
 555     get_buffer(s->pb, pkt->data, pkt->size);
 556     pkt->pts = pts;
 557     pkt->dts = dts;
 558     pkt->stream_index = st->index;
 559 #if 0
 560     av_log(s, AV_LOG_DEBUG, "%d: pts=%0.3f dts=%0.3f size=%d\n",
 561            pkt->stream_index, pkt->pts / 90000.0, pkt->dts / 90000.0, pkt->size);
 562 #endif
 563
 564     return 0;
 565 }
 566
 567 static int64_t mpegps_read_dts(AVFormatContext *s, int stream_index,
 568                                int64_t *ppos, int64_t pos_limit)
 569 {
 570     int len, startcode;
 571     int64_t pos, pts, dts;
 572
 573     pos = *ppos;
 574 #ifdef DEBUG_SEEK
 575     printf("read_dts: pos=0x%"PRIx64" next=%d -> ", pos, find_next);
 576 #endif
 577     if (url_fseek(s->pb, pos, SEEK_SET) < 0)
 578         return AV_NOPTS_VALUE;
 579
 580     for(;;) {
 581         len = mpegps_read_pes_header(s, &pos, &startcode, &pts, &dts);
 582         if (len < 0) {
 583 #ifdef DEBUG_SEEK
 584             printf("none (ret=%d)\n", len);
 585 #endif
 586             return AV_NOPTS_VALUE;
 587         }
 588         if (startcode == s->streams[stream_index]->id &&
 589             dts != AV_NOPTS_VALUE) {
 590             break;
 591         }
 592         url_fskip(s->pb, len);
 593     }
 594 #ifdef DEBUG_SEEK
 595     printf("pos=0x%"PRIx64" dts=0x%"PRIx64" %0.3f\n", pos, dts, dts / 90000.0);
 596 #endif
 597     *ppos = pos;
 598     return dts;
 599 }
 600
 601 AVInputFormat mpegps_demuxer = {
 602     "mpeg",
 603     NULL_IF_CONFIG_SMALL("MPEG-PS format"),
 604     sizeof(MpegDemuxContext),
 605     mpegps_probe,
 606     mpegps_read_header,
 607     mpegps_read_packet,
 608     NULL,
 609     NULL, //mpegps_read_seek,
 610     mpegps_read_dts,
 611     .flags = AVFMT_SHOW_IDS|AVFMT_TS_DISCONT,
 612 };