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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;

  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.     }

  90. 

  91.     if(vid || audio)            /* invalid VDR files nd short PES streams */

  92.         score= AVPROBE_SCORE_MAX/4;

  93. 

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

  95.     if(sys && sys*9 <= pspack*10)

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

  97.     if((priv1 || vid || audio) && (priv1+vid+audio)*9 <= pspack*10)

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

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

  100.         return AVPROBE_SCORE_MAX/2+2;

  101. 

  102.     //02-Penguin.flac has sys:0 priv1:0 pspack:0 vid:0 audio:1

  103.     return score;

  104. }

  105. 

  106. 

  107. typedef struct MpegDemuxContext {

  108.     int32_t header_state;

  109.     unsigned char psm_es_type[256];

  110.     int sofdec;

  111. } MpegDemuxContext;

  112. 

  113. static int mpegps_read_header(AVFormatContext *s,

  114.                               AVFormatParameters *ap)

  115. {

  116.     MpegDemuxContext *m = s->priv_data;

  117.     const char *sofdec = "Sofdec";

  118.     int v, i = 0;

  119. 

  120.     m->header_state = 0xff;

  121.     s->ctx_flags |= AVFMTCTX_NOHEADER;

  122. 

  123.     m->sofdec = -1;

  124.     do {

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

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

  127.         m->sofdec++;

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

  129. 

  130.     /* no need to do more */

  131.     return 0;

  132. }

  133. 

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

  135. {

  136.     int64_t pts;

  137.     int val;

  138. 

  139.     if (c < 0)

  140.         c = get_byte(pb);

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

  142.     val = get_be16(pb);

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

  144.     val = get_be16(pb);

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

  146.     return pts;

  147. }

  148. 

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

  150.                                 int32_t *header_state)

  151. {

  152.     unsigned int state, v;

  153.     int val, n;

  154. 

  155.     state = *header_state;

  156.     n = *size_ptr;

  157.     while (n > 0) {

  158.         if (url_feof(pb))

  159.             break;

  160.         v = get_byte(pb);

  161.         n--;

  162.         if (state == 0x000001) {

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

  164.             val = state;

  165.             goto found;

  166.         }

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

  168.     }

  169.     val = -1;

  170.  found:

  171.     *header_state = state;

  172.     *size_ptr = n;

  173.     return val;

  174. }

  175. 

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

  177. /* XXX: optimize */

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

  179. {

  180.     int64_t pos, pos_start;

  181.     int max_size, start_code;

  182. 

  183.     max_size = *size_ptr;

  184.     pos_start = url_ftell(pb);

  185. 

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

  187.     pos = pos_start - 16386;

  188.     if (pos < 0)

  189.         pos = 0;

  190.     url_fseek(pb, pos, SEEK_SET);

  191.     get_byte(pb);

  192. 

  193.     pos = pos_start;

  194.     for(;;) {

  195.         pos--;

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

  197.             start_code = -1;

  198.             goto the_end;

  199.         }

  200.         url_fseek(pb, pos, SEEK_SET);

  201.         start_code = get_be32(pb);

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

  203.             break;

  204.     }

  205.  the_end:

  206.     *size_ptr = pos_start - pos;

  207.     return start_code;

  208. }

  209. #endif

  210. 

  211. /**

  212.  * Extracts stream types from a program stream map

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

  214.  *

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

  216.  */

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

  218. {

  219.     int psm_length, ps_info_length, es_map_length;

  220. 

  221.     psm_length = get_be16(pb);

  222.     get_byte(pb);

  223.     get_byte(pb);

  224.     ps_info_length = get_be16(pb);

  225. 

  226.     /* skip program_stream_info */

  227.     url_fskip(pb, ps_info_length);

  228.     es_map_length = get_be16(pb);

  229. 

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

  231.     while (es_map_length >= 4){

  232.         unsigned char type = get_byte(pb);

  233.         unsigned char es_id = get_byte(pb);

  234.         uint16_t es_info_length = get_be16(pb);

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

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

  237.         /* skip program_stream_info */

  238.         url_fskip(pb, es_info_length);

  239.         es_map_length -= 4 + es_info_length;

  240.     }

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

  242.     return 2 + psm_length;

  243. }

  244. 

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

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

  247.  */

  248. static int mpegps_read_pes_header(AVFormatContext *s,

  249.                                   int64_t *ppos, int *pstart_code,

  250.                                   int64_t *ppts, int64_t *pdts)

  251. {

  252.     MpegDemuxContext *m = s->priv_data;

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

  254.     int pes_ext, ext2_len, id_ext, skip;

  255.     int64_t pts, dts;

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

  257. 

  258.  error_redo:

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

  260.  redo:

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

  262.         m->header_state = 0xff;

  263.         size = MAX_SYNC_SIZE;

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

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

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

  267.     if (startcode < 0)

  268.         return AVERROR(EIO);

  269.     if (startcode == PACK_START_CODE)

  270.         goto redo;

  271.     if (startcode == SYSTEM_HEADER_START_CODE)

  272.         goto redo;

  273.     if (startcode == PADDING_STREAM) {

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

  275.         goto redo;

  276.     }

  277.     if (startcode == PRIVATE_STREAM_2) {

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

  279.         if (!m->sofdec) {

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

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

  282.                     uint8_t buf[5];

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

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

  285.                     len -= sizeof(buf);

  286.                     break;

  287.                 }

  288.             }

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

  290.         }

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

  292.         goto redo;

  293.     }

  294.     if (startcode == PROGRAM_STREAM_MAP) {

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

  296.         goto redo;

  297.     }

  298. 

  299.     /* find matching stream */

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

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

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

  303.         goto redo;

  304.     if (ppos) {

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

  306.     }

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

  308.     pts =

  309.     dts = AV_NOPTS_VALUE;

  310.     /* stuffing */

  311.     for(;;) {

  312.         if (len < 1)

  313.             goto error_redo;

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

  315.         len--;

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

  317.         if (c != 0xff)

  318.             break;

  319.     }

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

  321.         /* buffer scale & size */

  322.         get_byte(s->pb);

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

  324.         len -= 2;

  325.     }

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

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

  328.         len -= 4;

  329.         if (c & 0x10){

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

  331.             len -= 5;

  332.         }

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

  334.         /* mpeg 2 PES */

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

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

  337.             /* Encrypted multiplex not handled */

  338.             goto redo;

  339.         }

  340. #endif

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

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

  343.         len -= 2;

  344.         if (header_len > len)

  345.             goto error_redo;

  346.         len -= header_len;

  347.         if (flags & 0x80) {

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

  349.             header_len -= 5;

  350.             if (flags & 0x40) {

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

  352.                 header_len -= 5;

  353.             }

  354.         }

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

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

  357.             header_len--;

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

  359.                 goto error_redo;

  360.             }

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

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

  363.             skip += skip & 0x9;

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

  365.             header_len -= skip;

  366. 

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

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

  369.                 header_len--;

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

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

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

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

  374.                     header_len--;

  375.                 }

  376.             }

  377.         }

  378.         if(header_len < 0)

  379.             goto error_redo;

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

  381.     }

  382.     else if( c!= 0xf )

  383.         goto redo;

  384. 

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

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

  387.         len--;

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

  389.             /* audio: skip header */

  390.             get_byte(s->pb);

  391.             get_byte(s->pb);

  392.             get_byte(s->pb);

  393.             len -= 3;

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

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

  396.                 get_byte(s->pb);

  397.                 len--;

  398.             }

  399.         }

  400.     }

  401.     if(len<0)

  402.         goto error_redo;

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

  404.         int i;

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

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

  407.                 av_add_index_entry(s->streams[i], *ppos, dts, 0, 0, AVINDEX_KEYFRAME /* FIXME keyframe? */);

  408.             }

  409.         }

  410.     }

  411. 

  412.     *pstart_code = startcode;

  413.     *ppts = pts;

  414.     *pdts = dts;

  415.     return len;

  416. }

  417. 

  418. static int mpegps_read_packet(AVFormatContext *s,

  419.                               AVPacket *pkt)

  420. {

  421.     MpegDemuxContext *m = s->priv_data;

  422.     AVStream *st;

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

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

  425. 

  426.  redo:

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

  428.     if (len < 0)

  429.         return len;

  430. 

  431.     /* now find stream */

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

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

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

  435.             goto found;

  436.     }

  437. 

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

  439.     if(es_type > 0){

  440.         if(es_type == STREAM_TYPE_VIDEO_MPEG1){

  441.             codec_id = CODEC_ID_MPEG2VIDEO;

  442.             type = CODEC_TYPE_VIDEO;

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

  444.             codec_id = CODEC_ID_MPEG2VIDEO;

  445.             type = CODEC_TYPE_VIDEO;

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

  447.                   es_type == STREAM_TYPE_AUDIO_MPEG2){

  448.             codec_id = CODEC_ID_MP3;

  449.             type = CODEC_TYPE_AUDIO;

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

  451.             codec_id = CODEC_ID_AAC;

  452.             type = CODEC_TYPE_AUDIO;

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

  454.             codec_id = CODEC_ID_MPEG4;

  455.             type = CODEC_TYPE_VIDEO;

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

  457.             codec_id = CODEC_ID_H264;

  458.             type = CODEC_TYPE_VIDEO;

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

  460.             codec_id = CODEC_ID_AC3;

  461.             type = CODEC_TYPE_AUDIO;

  462.         } else {

  463.             goto skip;

  464.         }

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

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

  467.         unsigned char buf[8];

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

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

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

  471.             codec_id = CODEC_ID_CAVS;

  472.         else

  473.             codec_id = CODEC_ID_MPEG2VIDEO;

  474.         type = CODEC_TYPE_VIDEO;

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

  476.         type = CODEC_TYPE_AUDIO;

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

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

  479.         type = CODEC_TYPE_AUDIO;

  480.         codec_id = CODEC_ID_AC3;

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

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

  483.         /* 0x90 - 0x97 is reserved for SDDS in DVD specs */

  484.         type = CODEC_TYPE_AUDIO;

  485.         codec_id = CODEC_ID_DTS;

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

  487.         type = CODEC_TYPE_AUDIO;

  488.         codec_id = CODEC_ID_PCM_S16BE;

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

  490.         type = CODEC_TYPE_AUDIO;

  491.         codec_id = CODEC_ID_MLP;

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

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

  494.         type = CODEC_TYPE_AUDIO;

  495.         codec_id = CODEC_ID_AC3;

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

  497.         type = CODEC_TYPE_SUBTITLE;

  498.         codec_id = CODEC_ID_DVD_SUBTITLE;

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

  500.         type = CODEC_TYPE_VIDEO;

  501.         codec_id = CODEC_ID_VC1;

  502.     } else {

  503.     skip:

  504.         /* skip packet */

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

  506.         goto redo;

  507.     }

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

  509.     st = av_new_stream(s, startcode);

  510.     if (!st)

  511.         goto skip;

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

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

  514.     if (codec_id != CODEC_ID_PCM_S16BE)

  515.         st->need_parsing = AVSTREAM_PARSE_FULL;

  516.  found:

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

  518.         goto skip;

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

  520.         int b1, freq;

  521. 

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

  523.            audio data */

  524.         if (len <= 3)

  525.             goto skip;

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

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

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

  529.         len -= 3;

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

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

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

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

  534.     }

  535.     av_new_packet(pkt, len);

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

  537.     pkt->pts = pts;

  538.     pkt->dts = dts;

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

  540. #if 0

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

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

  543. #endif

  544. 

  545.     return 0;

  546. }

  547. 

  548. static int mpegps_read_close(AVFormatContext *s)

  549. {

  550.     return 0;

  551. }

  552. 

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

  554.                                int64_t *ppos, int64_t pos_limit)

  555. {

  556.     int len, startcode;

  557.     int64_t pos, pts, dts;

  558. 

  559.     pos = *ppos;

  560. #ifdef DEBUG_SEEK

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

  562. #endif

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

  564.     for(;;) {

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

  566.         if (len < 0) {

  567. #ifdef DEBUG_SEEK

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

  569. #endif

  570.             return AV_NOPTS_VALUE;

  571.         }

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

  573.             dts != AV_NOPTS_VALUE) {

  574.             break;

  575.         }

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

  577.     }

  578. #ifdef DEBUG_SEEK

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

  580. #endif

  581.     *ppos = pos;

  582.     return dts;

  583. }

  584. 

  585. AVInputFormat mpegps_demuxer = {

  586.     "mpeg",

  587.     "MPEG PS format",

  588.     sizeof(MpegDemuxContext),

  589.     mpegps_probe,

  590.     mpegps_read_header,

  591.     mpegps_read_packet,

  592.     mpegps_read_close,

  593.     NULL, //mpegps_read_seek,

  594.     mpegps_read_dts,

  595.     .flags = AVFMT_SHOW_IDS,

  596. };