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