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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 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 cdxa_probe(AVProbeData *p)

  36. {

  37.     /* check file header */

  38.     if (p->buf[0] == 'R' && p->buf[1] == 'I' &&

  39.         p->buf[2] == 'F' && p->buf[3] == 'F' &&

  40.         p->buf[8] == 'C' && p->buf[9] == 'D' &&

  41.         p->buf[10] == 'X' && p->buf[11] == 'A')

  42.         return AVPROBE_SCORE_MAX;

  43.     else

  44.         return 0;

  45. }

  46. 

  47. static int check_pes(uint8_t *p, uint8_t *end){

  48.     int pes1;

  49.     int pes2=      (p[3] & 0xC0) == 0x80

  50.                 && (p[4] & 0xC0) != 0x40

  51.                 &&((p[4] & 0xC0) == 0x00 || (p[4]&0xC0)>>2 == (p[6]&0xF0));

  52. 

  53.     for(p+=3; p<end && *p == 0xFF; p++);

  54.     if((*p&0xC0) == 0x40) p+=2;

  55.     if((*p&0xF0) == 0x20){

  56.         pes1= p[0]&p[2]&p[4]&1;

  57.         p+=5;

  58.     }else if((*p&0xF0) == 0x30){

  59.         pes1= p[0]&p[2]&p[4]&p[5]&p[7]&p[9]&1;

  60.         p+=10;

  61.     }else

  62.         pes1 = *p == 0x0F;

  63. 

  64.     return pes1||pes2;

  65. }

  66. 

  67. static int mpegps_probe(AVProbeData *p)

  68. {

  69.     uint32_t code= -1;

  70.     int sys=0, pspack=0, priv1=0, vid=0, audio=0, invalid=0;

  71.     int i;

  72.     int score=0;

  73. 

  74.     score = cdxa_probe(p);

  75.     if (score > 0) return score;

  76. 

  77.     /* Search for MPEG stream */

  78.     for(i=0; i<p->buf_size; i++){

  79.         code = (code<<8) + p->buf[i];

  80.         if ((code & 0xffffff00) == 0x100) {

  81.             int pes= check_pes(p->buf+i, p->buf+p->buf_size);

  82. 

  83.             if(code == SYSTEM_HEADER_START_CODE) sys++;

  84.             else if(code == PRIVATE_STREAM_1)    priv1++;

  85.             else if(code == PACK_START_CODE)     pspack++;

  86.             else if((code & 0xf0) == VIDEO_ID && pes) vid++;

  87.             else if((code & 0xe0) == AUDIO_ID && pes) audio++;

  88. 

  89.             else if((code & 0xf0) == VIDEO_ID && !pes) invalid++;

  90.             else if((code & 0xe0) == AUDIO_ID && !pes) invalid++;

  91.         }

  92.     }

  93. 

  94.     if(vid+audio > invalid)     /* invalid VDR files nd short PES streams */

  95.         score= AVPROBE_SCORE_MAX/4;

  96. 

  97. //av_log(NULL, AV_LOG_ERROR, "%d %d %d %d %d len:%d\n", sys, priv1, pspack,vid, audio, p->buf_size);

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

  99.         return AVPROBE_SCORE_MAX/2+2; // +1 for .mpg

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

  101.         return AVPROBE_SCORE_MAX/2+2; // +1 for .mpg

  102.     if((!!vid ^ !!audio) && (audio+vid > 1) && !sys && !pspack && p->buf_size>2048) /* PES stream */

  103.         return AVPROBE_SCORE_MAX/2+2;

  104. 

  105.     //02-Penguin.flac has sys:0 priv1:0 pspack:0 vid:0 audio:1

  106.     return score;

  107. }

  108. 

  109. 

  110. typedef struct MpegDemuxContext {

  111.     int32_t header_state;

  112.     unsigned char psm_es_type[256];

  113.     int sofdec;

  114. } MpegDemuxContext;

  115. 

  116. static int mpegps_read_header(AVFormatContext *s,

  117.                               AVFormatParameters *ap)

  118. {

  119.     MpegDemuxContext *m = s->priv_data;

  120.     const char *sofdec = "Sofdec";

  121.     int v, i = 0;

  122. 

  123.     m->header_state = 0xff;

  124.     s->ctx_flags |= AVFMTCTX_NOHEADER;

  125. 

  126.     m->sofdec = -1;

  127.     do {

  128.         v = get_byte(s->pb);

  129.         m->header_state = m->header_state << 8 | v;

  130.         m->sofdec++;

  131.     } while (v == sofdec[i] && i++ < 6);

  132. 

  133.     /* no need to do more */

  134.     return 0;

  135. }

  136. 

  137. static int64_t get_pts(ByteIOContext *pb, int c)

  138. {

  139.     int64_t pts;

  140.     int val;

  141. 

  142.     if (c < 0)

  143.         c = get_byte(pb);

  144.     pts = (int64_t)((c >> 1) & 0x07) << 30;

  145.     val = get_be16(pb);

  146.     pts |= (int64_t)(val >> 1) << 15;

  147.     val = get_be16(pb);

  148.     pts |= (int64_t)(val >> 1);

  149.     return pts;

  150. }

  151. 

  152. static int find_next_start_code(ByteIOContext *pb, int *size_ptr,

  153.                                 int32_t *header_state)

  154. {

  155.     unsigned int state, v;

  156.     int val, n;

  157. 

  158.     state = *header_state;

  159.     n = *size_ptr;

  160.     while (n > 0) {

  161.         if (url_feof(pb))

  162.             break;

  163.         v = get_byte(pb);

  164.         n--;

  165.         if (state == 0x000001) {

  166.             state = ((state << 8) | v) & 0xffffff;

  167.             val = state;

  168.             goto found;

  169.         }

  170.         state = ((state << 8) | v) & 0xffffff;

  171.     }

  172.     val = -1;

  173.  found:

  174.     *header_state = state;

  175.     *size_ptr = n;

  176.     return val;

  177. }

  178. 

  179. #if 0 /* unused, remove? */

  180. /* XXX: optimize */

  181. static int find_prev_start_code(ByteIOContext *pb, int *size_ptr)

  182. {

  183.     int64_t pos, pos_start;

  184.     int max_size, start_code;

  185. 

  186.     max_size = *size_ptr;

  187.     pos_start = url_ftell(pb);

  188. 

  189.     /* in order to go faster, we fill the buffer */

  190.     pos = pos_start - 16386;

  191.     if (pos < 0)

  192.         pos = 0;

  193.     url_fseek(pb, pos, SEEK_SET);

  194.     get_byte(pb);

  195. 

  196.     pos = pos_start;

  197.     for(;;) {

  198.         pos--;

  199.         if (pos < 0 || (pos_start - pos) >= max_size) {

  200.             start_code = -1;

  201.             goto the_end;

  202.         }

  203.         url_fseek(pb, pos, SEEK_SET);

  204.         start_code = get_be32(pb);

  205.         if ((start_code & 0xffffff00) == 0x100)

  206.             break;

  207.     }

  208.  the_end:

  209.     *size_ptr = pos_start - pos;

  210.     return start_code;

  211. }

  212. #endif

  213. 

  214. /**

  215.  * Extracts stream types from a program stream map

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

  217.  *

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

  219.  */

  220. static long mpegps_psm_parse(MpegDemuxContext *m, ByteIOContext *pb)

  221. {

  222.     int psm_length, ps_info_length, es_map_length;

  223. 

  224.     psm_length = get_be16(pb);

  225.     get_byte(pb);

  226.     get_byte(pb);

  227.     ps_info_length = get_be16(pb);

  228. 

  229.     /* skip program_stream_info */

  230.     url_fskip(pb, ps_info_length);

  231.     es_map_length = get_be16(pb);

  232. 

  233.     /* at least one es available? */

  234.     while (es_map_length >= 4){

  235.         unsigned char type = get_byte(pb);

  236.         unsigned char es_id = get_byte(pb);

  237.         uint16_t es_info_length = get_be16(pb);

  238.         /* remember mapping from stream id to stream type */

  239.         m->psm_es_type[es_id] = type;

  240.         /* skip program_stream_info */

  241.         url_fskip(pb, es_info_length);

  242.         es_map_length -= 4 + es_info_length;

  243.     }

  244.     get_be32(pb); /* crc32 */

  245.     return 2 + psm_length;

  246. }

  247. 

  248. /* read the next PES header. Return its position in ppos

  249.    (if not NULL), and its start code, pts and dts.

  250.  */

  251. static int mpegps_read_pes_header(AVFormatContext *s,

  252.                                   int64_t *ppos, int *pstart_code,

  253.                                   int64_t *ppts, int64_t *pdts)

  254. {

  255.     MpegDemuxContext *m = s->priv_data;

  256.     int len, size, startcode, c, flags, header_len;

  257.     int pes_ext, ext2_len, id_ext, skip;

  258.     int64_t pts, dts;

  259.     int64_t last_sync= url_ftell(s->pb);

  260. 

  261.  error_redo:

  262.         url_fseek(s->pb, last_sync, SEEK_SET);

  263.  redo:

  264.         /* next start code (should be immediately after) */

  265.         m->header_state = 0xff;

  266.         size = MAX_SYNC_SIZE;

  267.         startcode = find_next_start_code(s->pb, &size, &m->header_state);

  268.         last_sync = url_ftell(s->pb);

  269.     //printf("startcode=%x pos=0x%"PRIx64"\n", startcode, url_ftell(s->pb));

  270.     if (startcode < 0)

  271.         return AVERROR(EIO);

  272.     if (startcode == PACK_START_CODE)

  273.         goto redo;

  274.     if (startcode == SYSTEM_HEADER_START_CODE)

  275.         goto redo;

  276.     if (startcode == PADDING_STREAM) {

  277.         url_fskip(s->pb, get_be16(s->pb));

  278.         goto redo;

  279.     }

  280.     if (startcode == PRIVATE_STREAM_2) {

  281.         len = get_be16(s->pb);

  282.         if (!m->sofdec) {

  283.             while (len-- >= 6) {

  284.                 if (get_byte(s->pb) == 'S') {

  285.                     uint8_t buf[5];

  286.                     get_buffer(s->pb, buf, sizeof(buf));

  287.                     m->sofdec = !memcmp(buf, "ofdec", 5);

  288.                     len -= sizeof(buf);

  289.                     break;

  290.                 }

  291.             }

  292.             m->sofdec -= !m->sofdec;

  293.         }

  294.         url_fskip(s->pb, len);

  295.         goto redo;

  296.     }

  297.     if (startcode == PROGRAM_STREAM_MAP) {

  298.         mpegps_psm_parse(m, s->pb);

  299.         goto redo;

  300.     }

  301. 

  302.     /* find matching stream */

  303.     if (!((startcode >= 0x1c0 && startcode <= 0x1df) ||

  304.           (startcode >= 0x1e0 && startcode <= 0x1ef) ||

  305.           (startcode == 0x1bd) || (startcode == 0x1fd)))

  306.         goto redo;

  307.     if (ppos) {

  308.         *ppos = url_ftell(s->pb) - 4;

  309.     }

  310.     len = get_be16(s->pb);

  311.     pts =

  312.     dts = AV_NOPTS_VALUE;

  313.     /* stuffing */

  314.     for(;;) {

  315.         if (len < 1)

  316.             goto error_redo;

  317.         c = get_byte(s->pb);

  318.         len--;

  319.         /* XXX: for mpeg1, should test only bit 7 */

  320.         if (c != 0xff)

  321.             break;

  322.     }

  323.     if ((c & 0xc0) == 0x40) {

  324.         /* buffer scale & size */

  325.         get_byte(s->pb);

  326.         c = get_byte(s->pb);

  327.         len -= 2;

  328.     }

  329.     if ((c & 0xe0) == 0x20) {

  330.         dts = pts = get_pts(s->pb, c);

  331.         len -= 4;

  332.         if (c & 0x10){

  333.             dts = get_pts(s->pb, -1);

  334.             len -= 5;

  335.         }

  336.     } else if ((c & 0xc0) == 0x80) {

  337.         /* mpeg 2 PES */

  338. #if 0 /* some streams have this field set for no apparent reason */

  339.         if ((c & 0x30) != 0) {

  340.             /* Encrypted multiplex not handled */

  341.             goto redo;

  342.         }

  343. #endif

  344.         flags = get_byte(s->pb);

  345.         header_len = get_byte(s->pb);

  346.         len -= 2;

  347.         if (header_len > len)

  348.             goto error_redo;

  349.         len -= header_len;

  350.         if (flags & 0x80) {

  351.             dts = pts = get_pts(s->pb, -1);

  352.             header_len -= 5;

  353.             if (flags & 0x40) {

  354.                 dts = get_pts(s->pb, -1);

  355.                 header_len -= 5;

  356.             }

  357.         }

  358.         if (flags & 0x01) { /* PES extension */

  359.             pes_ext = get_byte(s->pb);

  360.             header_len--;

  361.             if (pes_ext & 0x40) { /* pack header - should be zero in PS */

  362.                 goto error_redo;

  363.             }

  364.             /* Skip PES private data, program packet sequence counter and P-STD buffer */

  365.             skip = (pes_ext >> 4) & 0xb;

  366.             skip += skip & 0x9;

  367.             url_fskip(s->pb, skip);

  368.             header_len -= skip;

  369. 

  370.             if (pes_ext & 0x01) { /* PES extension 2 */

  371.                 ext2_len = get_byte(s->pb);

  372.                 header_len--;

  373.                 if ((ext2_len & 0x7f) > 0) {

  374.                     id_ext = get_byte(s->pb);

  375.                     if ((id_ext & 0x80) == 0)

  376.                         startcode = ((startcode & 0xff) << 8) | id_ext;

  377.                     header_len--;

  378.                 }

  379.             }

  380.         }

  381.         if(header_len < 0)

  382.             goto error_redo;

  383.         url_fskip(s->pb, header_len);

  384.     }

  385.     else if( c!= 0xf )

  386.         goto redo;

  387. 

  388.     if (startcode == PRIVATE_STREAM_1 && !m->psm_es_type[startcode & 0xff]) {

  389.         startcode = get_byte(s->pb);

  390.         len--;

  391.         if (startcode >= 0x80 && startcode <= 0xcf) {

  392.             /* audio: skip header */

  393.             get_byte(s->pb);

  394.             get_byte(s->pb);

  395.             get_byte(s->pb);

  396.             len -= 3;

  397.             if (startcode >= 0xb0 && startcode <= 0xbf) {

  398.                 /* MLP/TrueHD audio has a 4-byte header */

  399.                 get_byte(s->pb);

  400.                 len--;

  401.             }

  402.         }

  403.     }

  404.     if(len<0)

  405.         goto error_redo;

  406.     if(dts != AV_NOPTS_VALUE && ppos){

  407.         int i;

  408.         for(i=0; i<s->nb_streams; i++){

  409.             if(startcode == s->streams[i]->id) {

  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. 

  421. static int mpegps_read_packet(AVFormatContext *s,

  422.                               AVPacket *pkt)

  423. {

  424.     MpegDemuxContext *m = s->priv_data;

  425.     AVStream *st;

  426.     int len, startcode, i, type, codec_id = 0, es_type;

  427.     int64_t pts, dts, dummy_pos; //dummy_pos is needed for the index building to work

  428. 

  429.  redo:

  430.     len = mpegps_read_pes_header(s, &dummy_pos, &startcode, &pts, &dts);

  431.     if (len < 0)

  432.         return len;

  433. 

  434.     /* now find stream */

  435.     for(i=0;i<s->nb_streams;i++) {

  436.         st = s->streams[i];

  437.         if (st->id == startcode)

  438.             goto found;

  439.     }

  440. 

  441.     es_type = m->psm_es_type[startcode & 0xff];

  442.     if(es_type > 0){

  443.         if(es_type == STREAM_TYPE_VIDEO_MPEG1){

  444.             codec_id = CODEC_ID_MPEG2VIDEO;

  445.             type = CODEC_TYPE_VIDEO;

  446.         } else if(es_type == STREAM_TYPE_VIDEO_MPEG2){

  447.             codec_id = CODEC_ID_MPEG2VIDEO;

  448.             type = CODEC_TYPE_VIDEO;

  449.         } else if(es_type == STREAM_TYPE_AUDIO_MPEG1 ||

  450.                   es_type == STREAM_TYPE_AUDIO_MPEG2){

  451.             codec_id = CODEC_ID_MP3;

  452.             type = CODEC_TYPE_AUDIO;

  453.         } else if(es_type == STREAM_TYPE_AUDIO_AAC){

  454.             codec_id = CODEC_ID_AAC;

  455.             type = CODEC_TYPE_AUDIO;

  456.         } else if(es_type == STREAM_TYPE_VIDEO_MPEG4){

  457.             codec_id = CODEC_ID_MPEG4;

  458.             type = CODEC_TYPE_VIDEO;

  459.         } else if(es_type == STREAM_TYPE_VIDEO_H264){

  460.             codec_id = CODEC_ID_H264;

  461.             type = CODEC_TYPE_VIDEO;

  462.         } else if(es_type == STREAM_TYPE_AUDIO_AC3){

  463.             codec_id = CODEC_ID_AC3;

  464.             type = CODEC_TYPE_AUDIO;

  465.         } else {

  466.             goto skip;

  467.         }

  468.     } else if (startcode >= 0x1e0 && startcode <= 0x1ef) {

  469.         static const unsigned char avs_seqh[4] = { 0, 0, 1, 0xb0 };

  470.         unsigned char buf[8];

  471.         get_buffer(s->pb, buf, 8);

  472.         url_fseek(s->pb, -8, SEEK_CUR);

  473.         if(!memcmp(buf, avs_seqh, 4) && (buf[6] != 0 || buf[7] != 1))

  474.             codec_id = CODEC_ID_CAVS;

  475.         else

  476.             codec_id = CODEC_ID_MPEG2VIDEO;

  477.         type = CODEC_TYPE_VIDEO;

  478.     } else if (startcode >= 0x1c0 && startcode <= 0x1df) {

  479.         type = CODEC_TYPE_AUDIO;

  480.         codec_id = m->sofdec > 0 ? CODEC_ID_ADPCM_ADX : CODEC_ID_MP2;

  481.     } else if (startcode >= 0x80 && startcode <= 0x87) {

  482.         type = CODEC_TYPE_AUDIO;

  483.         codec_id = CODEC_ID_AC3;

  484.     } else if ((startcode >= 0x88 && startcode <= 0x8f)

  485.                ||( startcode >= 0x98 && startcode <= 0x9f)) {

  486.         /* 0x90 - 0x97 is reserved for SDDS in DVD specs */

  487.         type = CODEC_TYPE_AUDIO;

  488.         codec_id = CODEC_ID_DTS;

  489.     } else if (startcode >= 0xa0 && startcode <= 0xaf) {

  490.         type = CODEC_TYPE_AUDIO;

  491.         codec_id = CODEC_ID_PCM_S16BE;

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

  493.         type = CODEC_TYPE_AUDIO;

  494.         codec_id = CODEC_ID_MLP;

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

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

  497.         type = CODEC_TYPE_AUDIO;

  498.         codec_id = CODEC_ID_AC3;

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

  500.         type = CODEC_TYPE_SUBTITLE;

  501.         codec_id = CODEC_ID_DVD_SUBTITLE;

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

  503.         type = CODEC_TYPE_VIDEO;

  504.         codec_id = CODEC_ID_VC1;

  505.     } else {

  506.     skip:

  507.         /* skip packet */

  508.         url_fskip(s->pb, len);

  509.         goto redo;

  510.     }

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

  512.     st = av_new_stream(s, startcode);

  513.     if (!st)

  514.         goto skip;

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

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

  517.     if (codec_id != CODEC_ID_PCM_S16BE)

  518.         st->need_parsing = AVSTREAM_PARSE_FULL;

  519.  found:

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

  521.         goto skip;

  522.     if (startcode >= 0xa0 && startcode <= 0xaf) {

  523.         int b1, freq;

  524. 

  525.         /* for LPCM, we just skip the header and consider it is raw

  526.            audio data */

  527.         if (len <= 3)

  528.             goto skip;

  529.         get_byte(s->pb); /* emphasis (1), muse(1), reserved(1), frame number(5) */

  530.         b1 = get_byte(s->pb); /* quant (2), freq(2), reserved(1), channels(3) */

  531.         get_byte(s->pb); /* dynamic range control (0x80 = off) */

  532.         len -= 3;

  533.         freq = (b1 >> 4) & 3;

  534.         st->codec->sample_rate = lpcm_freq_tab[freq];

  535.         st->codec->channels = 1 + (b1 & 7);

  536.         st->codec->bit_rate = st->codec->channels * st->codec->sample_rate * 2;

  537.     }

  538.     av_new_packet(pkt, len);

  539.     get_buffer(s->pb, pkt->data, pkt->size);

  540.     pkt->pts = pts;

  541.     pkt->dts = dts;

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

  543. #if 0

  544.     av_log(s, AV_LOG_DEBUG, "%d: pts=%0.3f dts=%0.3f size=%d\n",

  545.            pkt->stream_index, pkt->pts / 90000.0, pkt->dts / 90000.0, pkt->size);

  546. #endif

  547. 

  548.     return 0;

  549. }

  550. 

  551. static int mpegps_read_close(AVFormatContext *s)

  552. {

  553.     return 0;

  554. }

  555. 

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

  557.                                int64_t *ppos, int64_t pos_limit)

  558. {

  559.     int len, startcode;

  560.     int64_t pos, pts, dts;

  561. 

  562.     pos = *ppos;

  563. #ifdef DEBUG_SEEK

  564.     printf("read_dts: pos=0x%"PRIx64" next=%d -> ", pos, find_next);

  565. #endif

  566.     url_fseek(s->pb, pos, SEEK_SET);

  567.     for(;;) {

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

  569.         if (len < 0) {

  570. #ifdef DEBUG_SEEK

  571.             printf("none (ret=%d)\n", len);

  572. #endif

  573.             return AV_NOPTS_VALUE;

  574.         }

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

  576.             dts != AV_NOPTS_VALUE) {

  577.             break;

  578.         }

  579.         url_fskip(s->pb, len);

  580.     }

  581. #ifdef DEBUG_SEEK

  582.     printf("pos=0x%"PRIx64" dts=0x%"PRIx64" %0.3f\n", pos, dts, dts / 90000.0);

  583. #endif

  584.     *ppos = pos;

  585.     return dts;

  586. }

  587. 

  588. AVInputFormat mpegps_demuxer = {

  589.     "mpeg",

  590.     "MPEG PS format",

  591.     sizeof(MpegDemuxContext),

  592.     mpegps_probe,

  593.     mpegps_read_header,

  594.     mpegps_read_packet,

  595.     mpegps_read_close,

  596.     NULL, //mpegps_read_seek,

  597.     mpegps_read_dts,

  598.     .flags = AVFMT_SHOW_IDS,

  599. };