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FFmpeg/libavformat/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_EXTENSION / 2;

  86. 

  87.     if(sys>invalid && sys*9 <= pspack*10)

  88.         return pspack > 2 ? AVPROBE_SCORE_EXTENSION + 2 : AVPROBE_SCORE_EXTENSION / 2; // 1 more than .mpg

  89.     if(pspack > invalid && (priv1+vid+audio)*10 >= pspack*9)

  90.         return pspack > 2 ? AVPROBE_SCORE_EXTENSION + 2 : AVPROBE_SCORE_EXTENSION / 2; // 1 more than .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_EXTENSION + 2 : AVPROBE_SCORE_EXTENSION / 2;

  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 {

  101.     int32_t header_state;

  102.     unsigned char psm_es_type[256];

  103.     int sofdec;

  104. } MpegDemuxContext;

  105. 

  106. static int mpegps_read_header(AVFormatContext *s)

  107. {

  108.     MpegDemuxContext *m = s->priv_data;

  109.     const char *sofdec = "Sofdec";

  110.     int v, i = 0;

  111. 

  112.     m->header_state = 0xff;

  113.     s->ctx_flags |= AVFMTCTX_NOHEADER;

  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. 

  165. /**

  166.  * Extract stream types from a program stream map

  167.  * According to ISO/IEC 13818-1 ('MPEG-2 Systems') table 2-35

  168.  *

  169.  * @return number of bytes occupied by PSM in the bitstream

  170.  */

  171. static long mpegps_psm_parse(MpegDemuxContext *m, AVIOContext *pb)

  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.  */

  202. static int mpegps_read_pes_header(AVFormatContext *s,

  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. 

  377. static int mpegps_read_packet(AVFormatContext *s,

  378.                               AVPacket *pkt)

  379. {

  380.     MpegDemuxContext *m = s->priv_data;

  381.     AVStream *st;

  382.     int len, startcode, i, es_type, ret;

  383.     enum AVCodecID codec_id = AV_CODEC_ID_NONE;

  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.         codec_id = AV_CODEC_ID_PCM_DVD;

  457.     } else if (startcode >= 0xb0 && startcode <= 0xbf) {

  458.         type = AVMEDIA_TYPE_AUDIO;

  459.         codec_id = AV_CODEC_ID_TRUEHD;

  460.     } else if (startcode >= 0xc0 && startcode <= 0xcf) {

  461.         /* Used for both AC-3 and E-AC-3 in EVOB files */

  462.         type = AVMEDIA_TYPE_AUDIO;

  463.         codec_id = AV_CODEC_ID_AC3;

  464.     } else if (startcode >= 0x20 && startcode <= 0x3f) {

  465.         type = AVMEDIA_TYPE_SUBTITLE;

  466.         codec_id = AV_CODEC_ID_DVD_SUBTITLE;

  467.     } else if (startcode >= 0xfd55 && startcode <= 0xfd5f) {

  468.         type = AVMEDIA_TYPE_VIDEO;

  469.         codec_id = AV_CODEC_ID_VC1;

  470.     } else if (startcode == 0x1bd) {

  471.         // check dvd audio substream type

  472.         type = AVMEDIA_TYPE_AUDIO;

  473.         switch(dvdaudio_substream_type & 0xe0) {

  474.         case 0xa0:  codec_id = AV_CODEC_ID_PCM_DVD;

  475.                     break;

  476.         case 0x80:  if((dvdaudio_substream_type & 0xf8) == 0x88)

  477.                          codec_id = AV_CODEC_ID_DTS;

  478.                     else codec_id = AV_CODEC_ID_AC3;

  479.                     break;

  480.         default:    av_log(s, AV_LOG_ERROR, "Unknown 0x1bd sub-stream\n");

  481.                     goto skip;

  482.         }

  483.     } else {

  484.     skip:

  485.         /* skip packet */

  486.         avio_skip(s->pb, len);

  487.         goto redo;

  488.     }

  489.     /* no stream found: add a new stream */

  490.     st = avformat_new_stream(s, NULL);

  491.     if (!st)

  492.         goto skip;

  493.     st->id = startcode;

  494.     st->codec->codec_type = type;

  495.     st->codec->codec_id = codec_id;

  496.     st->need_parsing = AVSTREAM_PARSE_FULL;

  497.  found:

  498.     if(st->discard >= AVDISCARD_ALL)

  499.         goto skip;

  500.     ret = av_get_packet(s->pb, pkt, len);

  501.     pkt->pts = pts;

  502.     pkt->dts = dts;

  503.     pkt->pos = dummy_pos;

  504.     pkt->stream_index = st->index;

  505.     av_dlog(s, "%d: pts=%0.3f dts=%0.3f size=%d\n",

  506.             pkt->stream_index, pkt->pts / 90000.0, pkt->dts / 90000.0,

  507.             pkt->size);

  508. 

  509.     return (ret < 0) ? ret : 0;

  510. }

  511. 

  512. static int64_t mpegps_read_dts(AVFormatContext *s, int stream_index,

  513.                                int64_t *ppos, int64_t pos_limit)

  514. {

  515.     int len, startcode;

  516.     int64_t pos, pts, dts;

  517. 

  518.     pos = *ppos;

  519.     if (avio_seek(s->pb, pos, SEEK_SET) < 0)

  520.         return AV_NOPTS_VALUE;

  521. 

  522.     for(;;) {

  523.         len = mpegps_read_pes_header(s, &pos, &startcode, &pts, &dts);

  524.         if (len < 0) {

  525.             av_dlog(s, "none (ret=%d)\n", len);

  526.             return AV_NOPTS_VALUE;

  527.         }

  528.         if (startcode == s->streams[stream_index]->id &&

  529.             dts != AV_NOPTS_VALUE) {

  530.             break;

  531.         }

  532.         avio_skip(s->pb, len);

  533.     }

  534.     av_dlog(s, "pos=0x%"PRIx64" dts=0x%"PRIx64" %0.3f\n",

  535.             pos, dts, dts / 90000.0);

  536.     *ppos = pos;

  537.     return dts;

  538. }

  539. 

  540. AVInputFormat ff_mpegps_demuxer = {

  541.     .name           = "mpeg",

  542.     .long_name      = NULL_IF_CONFIG_SMALL("MPEG-PS (MPEG-2 Program Stream)"),

  543.     .priv_data_size = sizeof(MpegDemuxContext),

  544.     .read_probe     = mpegps_probe,

  545.     .read_header    = mpegps_read_header,

  546.     .read_packet    = mpegps_read_packet,

  547.     .read_timestamp = mpegps_read_dts,

  548.     .flags          = AVFMT_SHOW_IDS | AVFMT_TS_DISCONT,

  549. };