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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 "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.             else if(code == 0x1fd             &&  pes) vid++; //VC1

  78. 

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

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

  81.             else if(code == PRIVATE_STREAM_1  && !pes) invalid++;

  82.         }

  83.     }

  84. 

  85.     if(vid+audio > invalid+1)     /* invalid VDR files nd short PES streams */

  86.         score= AVPROBE_SCORE_MAX/4;

  87. 

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

  89.         return (audio > 12 || vid > 3 || pspack > 2) ? AVPROBE_SCORE_MAX/2+2 : AVPROBE_SCORE_MAX/4; // +1 for .mpg

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

  91.         return pspack > 2 ? AVPROBE_SCORE_MAX/2+2 : AVPROBE_SCORE_MAX/4; // +1 for .mpg

  92.     if((!!vid ^ !!audio) && (audio > 4 || vid > 1) && !sys && !pspack && p->buf_size>2048 && vid + audio > invalid) /* PES stream */

  93.         return (audio > 12 || vid > 3 + 2*invalid) ? AVPROBE_SCORE_MAX/2+2 : AVPROBE_SCORE_MAX/4;

  94. 

  95.     //02-Penguin.flac has sys:0 priv1:0 pspack:0 vid:0 audio:1

  96.     //mp3_misidentified_2.mp3 has sys:0 priv1:0 pspack:0 vid:0 audio:6

  97.     //Have\ Yourself\ a\ Merry\ Little\ Christmas.mp3 0 0 0 5 0 1 len:21618

  98.     return score;

  99. }

  100. 

  101. 

  102. typedef struct MpegDemuxContext {

  103.     int32_t header_state;

  104.     unsigned char psm_es_type[256];

  105.     int sofdec;

  106. } MpegDemuxContext;

  107. 

  108. static int mpegps_read_header(AVFormatContext *s)

  109. {

  110.     MpegDemuxContext *m = s->priv_data;

  111.     const char *sofdec = "Sofdec";

  112.     int v, i = 0;

  113.     int64_t last_pos = avio_tell(s->pb);

  114. 

  115.     m->header_state = 0xff;

  116.     s->ctx_flags |= AVFMTCTX_NOHEADER;

  117. 

  118.     m->sofdec = -1;

  119.     do {

  120.         v = avio_r8(s->pb);

  121.         m->sofdec++;

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

  123. 

  124.     m->sofdec = (m->sofdec == 6) ? 1 : 0;

  125. 

  126.     if (!m->sofdec)

  127.        avio_seek(s->pb, last_pos, SEEK_SET);

  128. 

  129.     /* no need to do more */

  130.     return 0;

  131. }

  132. 

  133. static int64_t get_pts(AVIOContext *pb, int c)

  134. {

  135.     uint8_t buf[5];

  136. 

  137.     buf[0] = c<0 ? avio_r8(pb) : c;

  138.     avio_read(pb, buf+1, 4);

  139. 

  140.     return ff_parse_pes_pts(buf);

  141. }

  142. 

  143. static int find_next_start_code(AVIOContext *pb, int *size_ptr,

  144.                                 int32_t *header_state)

  145. {

  146.     unsigned int state, v;

  147.     int val, n;

  148. 

  149.     state = *header_state;

  150.     n = *size_ptr;

  151.     while (n > 0) {

  152.         if (url_feof(pb))

  153.             break;

  154.         v = avio_r8(pb);

  155.         n--;

  156.         if (state == 0x000001) {

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

  158.             val = state;

  159.             goto found;

  160.         }

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

  162.     }

  163.     val = -1;

  164.  found:

  165.     *header_state = state;

  166.     *size_ptr = n;

  167.     return val;

  168. }

  169. 

  170. /**

  171.  * Extract stream types from a program stream map

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

  173.  *

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

  175.  */

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

  177. {

  178.     int psm_length, ps_info_length, es_map_length;

  179. 

  180.     psm_length = avio_rb16(pb);

  181.     avio_r8(pb);

  182.     avio_r8(pb);

  183.     ps_info_length = avio_rb16(pb);

  184. 

  185.     /* skip program_stream_info */

  186.     avio_skip(pb, ps_info_length);

  187.     es_map_length = avio_rb16(pb);

  188. 

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

  190.     while (es_map_length >= 4){

  191.         unsigned char type      = avio_r8(pb);

  192.         unsigned char es_id     = avio_r8(pb);

  193.         uint16_t es_info_length = avio_rb16(pb);

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

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

  196.         /* skip program_stream_info */

  197.         avio_skip(pb, es_info_length);

  198.         es_map_length -= 4 + es_info_length;

  199.     }

  200.     avio_rb32(pb); /* crc32 */

  201.     return 2 + psm_length;

  202. }

  203. 

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

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

  206.  */

  207. static int mpegps_read_pes_header(AVFormatContext *s,

  208.                                   int64_t *ppos, int *pstart_code,

  209.                                   int64_t *ppts, int64_t *pdts)

  210. {

  211.     MpegDemuxContext *m = s->priv_data;

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

  213.     int pes_ext, ext2_len, id_ext, skip;

  214.     int64_t pts, dts;

  215.     int64_t last_sync= avio_tell(s->pb);

  216. 

  217.  error_redo:

  218.         avio_seek(s->pb, last_sync, SEEK_SET);

  219.  redo:

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

  221.         m->header_state = 0xff;

  222.         size = MAX_SYNC_SIZE;

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

  224.         last_sync = avio_tell(s->pb);

  225.     if (startcode < 0){

  226.         if(url_feof(s->pb))

  227.             return AVERROR_EOF;

  228.         //FIXME we should remember header_state

  229.         return AVERROR(EAGAIN);

  230.     }

  231. 

  232.     if (startcode == PACK_START_CODE)

  233.         goto redo;

  234.     if (startcode == SYSTEM_HEADER_START_CODE)

  235.         goto redo;

  236.     if (startcode == PADDING_STREAM) {

  237.         avio_skip(s->pb, avio_rb16(s->pb));

  238.         goto redo;

  239.     }

  240.     if (startcode == PRIVATE_STREAM_2) {

  241.         len = avio_rb16(s->pb);

  242.         if (!m->sofdec) {

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

  244.                 if (avio_r8(s->pb) == 'S') {

  245.                     uint8_t buf[5];

  246.                     avio_read(s->pb, buf, sizeof(buf));

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

  248.                     len -= sizeof(buf);

  249.                     break;

  250.                 }

  251.             }

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

  253.         }

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

  255.         goto redo;

  256.     }

  257.     if (startcode == PROGRAM_STREAM_MAP) {

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

  259.         goto redo;

  260.     }

  261. 

  262.     /* find matching stream */

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

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

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

  266.         goto redo;

  267.     if (ppos) {

  268.         *ppos = avio_tell(s->pb) - 4;

  269.     }

  270.     len = avio_rb16(s->pb);

  271.     pts =

  272.     dts = AV_NOPTS_VALUE;

  273.     /* stuffing */

  274.     for(;;) {

  275.         if (len < 1)

  276.             goto error_redo;

  277.         c = avio_r8(s->pb);

  278.         len--;

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

  280.         if (c != 0xff)

  281.             break;

  282.     }

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

  284.         /* buffer scale & size */

  285.         avio_r8(s->pb);

  286.         c = avio_r8(s->pb);

  287.         len -= 2;

  288.     }

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

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

  291.         len -= 4;

  292.         if (c & 0x10){

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

  294.             len -= 5;

  295.         }

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

  297.         /* mpeg 2 PES */

  298.         flags = avio_r8(s->pb);

  299.         header_len = avio_r8(s->pb);

  300.         len -= 2;

  301.         if (header_len > len)

  302.             goto error_redo;

  303.         len -= header_len;

  304.         if (flags & 0x80) {

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

  306.             header_len -= 5;

  307.             if (flags & 0x40) {

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

  309.                 header_len -= 5;

  310.             }

  311.         }

  312.         if (flags & 0x3f && header_len == 0){

  313.             flags &= 0xC0;

  314.             av_log(s, AV_LOG_WARNING, "Further flags set but no bytes left\n");

  315.         }

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

  317.             pes_ext = avio_r8(s->pb);

  318.             header_len--;

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

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

  321.             skip += skip & 0x9;

  322.             if (pes_ext & 0x40 || skip > header_len){

  323.                 av_log(s, AV_LOG_WARNING, "pes_ext %X is invalid\n", pes_ext);

  324.                 pes_ext=skip=0;

  325.             }

  326.             avio_skip(s->pb, skip);

  327.             header_len -= skip;

  328. 

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

  330.                 ext2_len = avio_r8(s->pb);

  331.                 header_len--;

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

  333.                     id_ext = avio_r8(s->pb);

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

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

  336.                     header_len--;

  337.                 }

  338.             }

  339.         }

  340.         if(header_len < 0)

  341.             goto error_redo;

  342.         avio_skip(s->pb, header_len);

  343.     }

  344.     else if( c!= 0xf )

  345.         goto redo;

  346. 

  347.     if (startcode == PRIVATE_STREAM_1) {

  348.         startcode = avio_r8(s->pb);

  349.         len--;

  350.     }

  351.     if(len<0)

  352.         goto error_redo;

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

  354.         int i;

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

  356.             if(startcode == s->streams[i]->id &&

  357.                s->pb->seekable /* index useless on streams anyway */) {

  358.                 ff_reduce_index(s, i);

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

  360.             }

  361.         }

  362.     }

  363. 

  364.     *pstart_code = startcode;

  365.     *ppts = pts;

  366.     *pdts = dts;

  367.     return len;

  368. }

  369. 

  370. static int mpegps_read_packet(AVFormatContext *s,

  371.                               AVPacket *pkt)

  372. {

  373.     MpegDemuxContext *m = s->priv_data;

  374.     AVStream *st;

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

  376.     int lpcm_header_len;

  377.     int request_probe= 0;

  378.     enum AVCodecID codec_id = AV_CODEC_ID_NONE;

  379.     enum AVMediaType type;

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

  381. 

  382.  redo:

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

  384.     if (len < 0)

  385.         return len;

  386. 

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

  388.         if(len < 4)

  389.             goto skip;

  390. 

  391.         /* audio: skip header */

  392.         avio_r8(s->pb);

  393.         lpcm_header_len = avio_rb16(s->pb);

  394.         len -= 3;

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

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

  397.             avio_r8(s->pb);

  398.             len--;

  399.         }

  400.     }

  401. 

  402.     /* now find stream */

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

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

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

  406.             goto found;

  407.     }

  408. 

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

  410.     if(es_type > 0 && es_type != STREAM_TYPE_PRIVATE_DATA){

  411.         if(es_type == STREAM_TYPE_VIDEO_MPEG1){

  412.             codec_id = AV_CODEC_ID_MPEG2VIDEO;

  413.             type = AVMEDIA_TYPE_VIDEO;

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

  415.             codec_id = AV_CODEC_ID_MPEG2VIDEO;

  416.             type = AVMEDIA_TYPE_VIDEO;

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

  418.                   es_type == STREAM_TYPE_AUDIO_MPEG2){

  419.             codec_id = AV_CODEC_ID_MP3;

  420.             type = AVMEDIA_TYPE_AUDIO;

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

  422.             codec_id = AV_CODEC_ID_AAC;

  423.             type = AVMEDIA_TYPE_AUDIO;

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

  425.             codec_id = AV_CODEC_ID_MPEG4;

  426.             type = AVMEDIA_TYPE_VIDEO;

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

  428.             codec_id = AV_CODEC_ID_H264;

  429.             type = AVMEDIA_TYPE_VIDEO;

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

  431.             codec_id = AV_CODEC_ID_AC3;

  432.             type = AVMEDIA_TYPE_AUDIO;

  433.         } else {

  434.             goto skip;

  435.         }

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

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

  438.         unsigned char buf[8];

  439.         avio_read(s->pb, buf, 8);

  440.         avio_seek(s->pb, -8, SEEK_CUR);

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

  442.             codec_id = AV_CODEC_ID_CAVS;

  443.         else

  444.             request_probe= 1;

  445.         type = AVMEDIA_TYPE_VIDEO;

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

  447.         type = AVMEDIA_TYPE_AUDIO;

  448.         codec_id = m->sofdec > 0 ? AV_CODEC_ID_ADPCM_ADX : AV_CODEC_ID_MP2;

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

  450.         type = AVMEDIA_TYPE_AUDIO;

  451.         codec_id = AV_CODEC_ID_AC3;

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

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

  454.         /* 0x90 - 0x97 is reserved for SDDS in DVD specs */

  455.         type = AVMEDIA_TYPE_AUDIO;

  456.         codec_id = AV_CODEC_ID_DTS;

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

  458.         type = AVMEDIA_TYPE_AUDIO;

  459.         if(lpcm_header_len == 6) {

  460.             codec_id = AV_CODEC_ID_MLP;

  461.         } else {

  462.             /* 16 bit form will be handled as AV_CODEC_ID_PCM_S16BE */

  463.             codec_id = AV_CODEC_ID_PCM_DVD;

  464.         }

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

  466.         type = AVMEDIA_TYPE_AUDIO;

  467.         codec_id = AV_CODEC_ID_TRUEHD;

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

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

  470.         type = AVMEDIA_TYPE_AUDIO;

  471.         codec_id = AV_CODEC_ID_AC3;

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

  473.         type = AVMEDIA_TYPE_SUBTITLE;

  474.         codec_id = AV_CODEC_ID_DVD_SUBTITLE;

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

  476.         type = AVMEDIA_TYPE_VIDEO;

  477.         codec_id = AV_CODEC_ID_VC1;

  478.     } else {

  479.     skip:

  480.         /* skip packet */

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

  482.         goto redo;

  483.     }

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

  485.     st = avformat_new_stream(s, NULL);

  486.     if (!st)

  487.         goto skip;

  488.     st->id = startcode;

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

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

  491.     st->request_probe     = request_probe;

  492.     if (codec_id != AV_CODEC_ID_PCM_S16BE)

  493.         st->need_parsing = AVSTREAM_PARSE_FULL;

  494.  found:

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

  496.         goto skip;

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

  498.       if (lpcm_header_len == 6) {

  499.             if (len < 6)

  500.                 goto skip;

  501.             avio_skip(s->pb, 6);

  502.             len -=6;

  503.       } else {

  504.         int b1, freq;

  505. 

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

  507.            audio data */

  508.         if (len <= 3)

  509.             goto skip;

  510.         avio_r8(s->pb); /* emphasis (1), muse(1), reserved(1), frame number(5) */

  511.         b1 = avio_r8(s->pb); /* quant (2), freq(2), reserved(1), channels(3) */

  512.         avio_r8(s->pb); /* dynamic range control (0x80 = off) */

  513.         len -= 3;

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

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

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

  517.         st->codec->bits_per_coded_sample = 16 + ((b1 >> 6) & 3) * 4;

  518.         st->codec->bit_rate = st->codec->channels *

  519.                               st->codec->sample_rate *

  520.                               st->codec->bits_per_coded_sample;

  521.         if (st->codec->bits_per_coded_sample == 16)

  522.             st->codec->codec_id = AV_CODEC_ID_PCM_S16BE;

  523.         else if (st->codec->bits_per_coded_sample == 28)

  524.             return AVERROR(EINVAL);

  525.       }

  526.     }

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

  528.     pkt->pts = pts;

  529.     pkt->dts = dts;

  530.     pkt->pos = dummy_pos;

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

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

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

  534.             pkt->size);

  535. 

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

  537. }

  538. 

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

  540.                                int64_t *ppos, int64_t pos_limit)

  541. {

  542.     int len, startcode;

  543.     int64_t pos, pts, dts;

  544. 

  545.     pos = *ppos;

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

  547.         return AV_NOPTS_VALUE;

  548. 

  549.     for(;;) {

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

  551.         if (len < 0) {

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

  553.             return AV_NOPTS_VALUE;

  554.         }

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

  556.             dts != AV_NOPTS_VALUE) {

  557.             break;

  558.         }

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

  560.     }

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

  562.             pos, dts, dts / 90000.0);

  563.     *ppos = pos;

  564.     return dts;

  565. }

  566. 

  567. AVInputFormat ff_mpegps_demuxer = {

  568.     .name           = "mpeg",

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

  570.     .priv_data_size = sizeof(MpegDemuxContext),

  571.     .read_probe     = mpegps_probe,

  572.     .read_header    = mpegps_read_header,

  573.     .read_packet    = mpegps_read_packet,

  574.     .read_timestamp = mpegps_read_dts,

  575.     .flags          = AVFMT_SHOW_IDS | AVFMT_TS_DISCONT,

  576. };