falkTX
/
FFmpeg
mirror of https://github.com/falkTX/FFmpeg.git
1
0
Fork 0
Code Issues 0 Releases 338 Wiki Activity
You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
39949 Commits
32 Branches
283MB
Tree: 853cc025d6
Branches Tags
${ item.name }
Create branch ${ searchTerm }
from '853cc025d6'
${ noResults }
FFmpeg/libavformat/mpeg.c

578 lines
18KB
Raw Blame History 

  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. {

  36.     int pes1;

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

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

  39.                ((p[4] & 0xC0) == 0x00 ||

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

  41. 

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

  43.     if ((*p & 0xC0) == 0x40)

  44.         p += 2;

  45. 

  46.     if ((*p & 0xF0) == 0x20)

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

  48.     else if ((*p & 0xF0) == 0x30)

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

  50.     else

  51.         pes1 = *p == 0x0F;

  52. 

  53.     return pes1 || pes2;

  54. }

  55. 

  56. static int check_pack_header(const uint8_t *buf)

  57. {

  58.     return (buf[1] & 0xC0) == 0x40 || (buf[1] & 0xF0) == 0x20;

  59. }

  60. 

  61. static int mpegps_probe(AVProbeData *p)

  62. {

  63.     uint32_t code = -1;

  64.     int i;

  65.     int sys = 0, pspack = 0, priv1 = 0, vid = 0;

  66.     int audio = 0, invalid = 0, score = 0;

  67. 

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

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

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

  71.             int len  = p->buf[i + 1] << 8 | p->buf[i + 2];

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

  73.             int pack = check_pack_header(p->buf + i);

  74. 

  75.             if (code == SYSTEM_HEADER_START_CODE)

  76.                 sys++;

  77.             else if (code == PACK_START_CODE && pack)

  78.                 pspack++;

  79.             else if ((code & 0xf0) == VIDEO_ID && pes)

  80.                 vid++;

  81.             // skip pes payload to avoid start code emulation for private

  82.             // and audio streams

  83.             else if ((code & 0xe0) == AUDIO_ID && pes) {

  84.                 audio++;

  85.                 i += len;

  86.             } else if (code == PRIVATE_STREAM_1 && pes) {

  87.                 priv1++;

  88.                 i += len;

  89.             } else if ((code & 0xf0) == VIDEO_ID && !pes)

  90.                 invalid++;

  91.             else if ((code & 0xe0) == AUDIO_ID && !pes)

  92.                 invalid++;

  93.             else if (code == PRIVATE_STREAM_1 && !pes)

  94.                 invalid++;

  95.         }

  96.     }

  97. 

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

  99.         score = AVPROBE_SCORE_EXTENSION / 2;

  100. 

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

  102.         return pspack > 2 ? AVPROBE_SCORE_EXTENSION + 2

  103.                           : AVPROBE_SCORE_EXTENSION / 2; // 1 more than .mpg

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

  105.         return pspack > 2 ? AVPROBE_SCORE_EXTENSION + 2

  106.                           : AVPROBE_SCORE_EXTENSION / 2; // 1 more than .mpg

  107.     if ((!!vid ^ !!audio) && (audio > 4 || vid > 1) && !sys &&

  108.         !pspack && p->buf_size > 2048 && vid + audio > invalid) /* PES stream */

  109.         return (audio > 12 || vid > 3) ? AVPROBE_SCORE_EXTENSION + 2

  110.                                        : AVPROBE_SCORE_EXTENSION / 2;

  111. 

  112.     // 02-Penguin.flac has sys:0 priv1:0 pspack:0 vid:0 audio:1

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

  114.     return score;

  115. }

  116. 

  117. typedef struct MpegDemuxContext {

  118.     int32_t header_state;

  119.     unsigned char psm_es_type[256];

  120.     int sofdec;

  121. } MpegDemuxContext;

  122. 

  123. static int mpegps_read_header(AVFormatContext *s)

  124. {

  125.     MpegDemuxContext *m = s->priv_data;

  126.     const char *sofdec  = "Sofdec";

  127.     int v, i = 0;

  128. 

  129.     m->header_state = 0xff;

  130.     s->ctx_flags   |= AVFMTCTX_NOHEADER;

  131. 

  132.     m->sofdec = -1;

  133.     do {

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

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

  136.         m->sofdec++;

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

  138. 

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

  140. 

  141.     /* no need to do more */

  142.     return 0;

  143. }

  144. 

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

  146. {

  147.     uint8_t buf[5];

  148. 

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

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

  151. 

  152.     return ff_parse_pes_pts(buf);

  153. }

  154. 

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

  156.                                 int32_t *header_state)

  157. {

  158.     unsigned int state, v;

  159.     int val, n;

  160. 

  161.     state = *header_state;

  162.     n     = *size_ptr;

  163.     while (n > 0) {

  164.         if (pb->eof_reached)

  165.             break;

  166.         v = avio_r8(pb);

  167.         n--;

  168.         if (state == 0x000001) {

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

  170.             val   = state;

  171.             goto found;

  172.         }

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

  174.     }

  175.     val = -1;

  176. 

  177. found:

  178.     *header_state = state;

  179.     *size_ptr     = n;

  180.     return val;

  181. }

  182. 

  183. /**

  184.  * Extract stream types from a program stream map

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

  186.  *

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

  188.  */

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

  190. {

  191.     int psm_length, ps_info_length, es_map_length;

  192. 

  193.     psm_length = avio_rb16(pb);

  194.     avio_r8(pb);

  195.     avio_r8(pb);

  196.     ps_info_length = avio_rb16(pb);

  197. 

  198.     /* skip program_stream_info */

  199.     avio_skip(pb, ps_info_length);

  200.     es_map_length = avio_rb16(pb);

  201. 

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

  203.     while (es_map_length >= 4) {

  204.         unsigned char type      = avio_r8(pb);

  205.         unsigned char es_id     = avio_r8(pb);

  206.         uint16_t es_info_length = avio_rb16(pb);

  207. 

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

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

  210.         /* skip program_stream_info */

  211.         avio_skip(pb, es_info_length);

  212.         es_map_length -= 4 + es_info_length;

  213.     }

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

  215.     return 2 + psm_length;

  216. }

  217. 

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

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

  220.  */

  221. static int mpegps_read_pes_header(AVFormatContext *s,

  222.                                   int64_t *ppos, int *pstart_code,

  223.                                   int64_t *ppts, int64_t *pdts)

  224. {

  225.     MpegDemuxContext *m = s->priv_data;

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

  227.     int pes_ext, ext2_len, id_ext, skip;

  228.     int64_t pts, dts;

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

  230. 

  231. error_redo:

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

  233. redo:

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

  235.     m->header_state = 0xff;

  236.     size      = MAX_SYNC_SIZE;

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

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

  239.     if (startcode < 0) {

  240.         if (s->pb->eof_reached)

  241.             return AVERROR_EOF;

  242.         // FIXME we should remember header_state

  243.         return AVERROR(EAGAIN);

  244.     }

  245. 

  246.     if (startcode == PACK_START_CODE)

  247.         goto redo;

  248.     if (startcode == SYSTEM_HEADER_START_CODE)

  249.         goto redo;

  250.     if (startcode == PADDING_STREAM) {

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

  252.         goto redo;

  253.     }

  254.     if (startcode == PRIVATE_STREAM_2) {

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

  256.         if (!m->sofdec) {

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

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

  259.                     uint8_t buf[5];

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

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

  262.                     len -= sizeof(buf);

  263.                     break;

  264.                 }

  265.             }

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

  267.         }

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

  269.         goto redo;

  270.     }

  271.     if (startcode == PROGRAM_STREAM_MAP) {

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

  273.         goto redo;

  274.     }

  275. 

  276.     /* find matching stream */

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

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

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

  280.         goto redo;

  281.     if (ppos) {

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

  283.     }

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

  285.     pts =

  286.     dts = AV_NOPTS_VALUE;

  287.     /* stuffing */

  288.     for (;;) {

  289.         if (len < 1)

  290.             goto error_redo;

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

  292.         len--;

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

  294.         if (c != 0xff)

  295.             break;

  296.     }

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

  298.         /* buffer scale & size */

  299.         avio_r8(s->pb);

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

  301.         len -= 2;

  302.     }

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

  304.         dts  =

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

  306.         len -= 4;

  307.         if (c & 0x10) {

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

  309.             len -= 5;

  310.         }

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

  312.         /* mpeg 2 PES */

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

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

  315.         len       -= 2;

  316.         if (header_len > len)

  317.             goto error_redo;

  318.         len -= header_len;

  319.         if (flags & 0x80) {

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

  321.             header_len -= 5;

  322.             if (flags & 0x40) {

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

  324.                 header_len -= 5;

  325.             }

  326.         }

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

  328.             flags &= 0xC0;

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

  330.         }

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

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

  333.             header_len--;

  334.             /* Skip PES private data, program packet sequence counter

  335.              * and P-STD buffer */

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

  337.             skip += skip & 0x9;

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

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

  340.                 pes_ext = skip = 0;

  341.             }

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

  343.             header_len -= skip;

  344. 

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

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

  347.                 header_len--;

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

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

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

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

  352.                     header_len--;

  353.                 }

  354.             }

  355.         }

  356.         if (header_len < 0)

  357.             goto error_redo;

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

  359.     } else if (c != 0xf)

  360.         goto redo;

  361. 

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

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

  364.         len--;

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

  366.             /* audio: skip header */

  367.             avio_r8(s->pb);

  368.             avio_r8(s->pb);

  369.             avio_r8(s->pb);

  370.             len -= 3;

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

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

  373.                 avio_r8(s->pb);

  374.                 len--;

  375.             }

  376.         }

  377.     }

  378.     if (len < 0)

  379.         goto error_redo;

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

  381.         int i;

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

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

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

  385.                 ff_reduce_index(s, i);

  386.                 av_add_index_entry(s->streams[i], *ppos, dts, 0, 0,

  387.                                    AVINDEX_KEYFRAME /* FIXME keyframe? */);

  388.             }

  389.         }

  390.     }

  391. 

  392.     *pstart_code = startcode;

  393.     *ppts        = pts;

  394.     *pdts        = dts;

  395.     return len;

  396. }

  397. 

  398. static int mpegps_read_packet(AVFormatContext *s,

  399.                               AVPacket *pkt)

  400. {

  401.     MpegDemuxContext *m = s->priv_data;

  402.     AVStream *st;

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

  404.     enum AVCodecID codec_id = AV_CODEC_ID_NONE;

  405.     enum AVMediaType type;

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

  407.     uint8_t av_uninit(dvdaudio_substream_type);

  408. 

  409. redo:

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

  411.     if (len < 0)

  412.         return len;

  413. 

  414.     if (startcode == 0x1bd) {

  415.         dvdaudio_substream_type = avio_r8(s->pb);

  416.         avio_skip(s->pb, 3);

  417.         len -= 4;

  418.     }

  419. 

  420.     /* now find stream */

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

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

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

  424.             goto found;

  425.     }

  426. 

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

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

  429.         if (es_type == STREAM_TYPE_VIDEO_MPEG1) {

  430.             codec_id = AV_CODEC_ID_MPEG2VIDEO;

  431.             type     = AVMEDIA_TYPE_VIDEO;

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

  433.             codec_id = AV_CODEC_ID_MPEG2VIDEO;

  434.             type     = AVMEDIA_TYPE_VIDEO;

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

  436.                    es_type == STREAM_TYPE_AUDIO_MPEG2) {

  437.             codec_id = AV_CODEC_ID_MP3;

  438.             type     = AVMEDIA_TYPE_AUDIO;

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

  440.             codec_id = AV_CODEC_ID_AAC;

  441.             type     = AVMEDIA_TYPE_AUDIO;

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

  443.             codec_id = AV_CODEC_ID_MPEG4;

  444.             type     = AVMEDIA_TYPE_VIDEO;

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

  446.             codec_id = AV_CODEC_ID_H264;

  447.             type     = AVMEDIA_TYPE_VIDEO;

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

  449.             codec_id = AV_CODEC_ID_AC3;

  450.             type     = AVMEDIA_TYPE_AUDIO;

  451.         } else {

  452.             goto skip;

  453.         }

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

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

  456.         unsigned char buf[8];

  457. 

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

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

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

  461.             codec_id = AV_CODEC_ID_CAVS;

  462.         else

  463.             codec_id = AV_CODEC_ID_PROBE;

  464.         type = AVMEDIA_TYPE_VIDEO;

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

  466.         type     = AVMEDIA_TYPE_AUDIO;

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

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

  469.         type     = AVMEDIA_TYPE_AUDIO;

  470.         codec_id = AV_CODEC_ID_AC3;

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

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

  473.         /* 0x90 - 0x97 is reserved for SDDS in DVD specs */

  474.         type     = AVMEDIA_TYPE_AUDIO;

  475.         codec_id = AV_CODEC_ID_DTS;

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

  477.         type     = AVMEDIA_TYPE_AUDIO;

  478.         codec_id = AV_CODEC_ID_PCM_DVD;

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

  480.         type     = AVMEDIA_TYPE_AUDIO;

  481.         codec_id = AV_CODEC_ID_TRUEHD;

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

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

  484.         type     = AVMEDIA_TYPE_AUDIO;

  485.         codec_id = AV_CODEC_ID_AC3;

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

  487.         type     = AVMEDIA_TYPE_SUBTITLE;

  488.         codec_id = AV_CODEC_ID_DVD_SUBTITLE;

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

  490.         type     = AVMEDIA_TYPE_VIDEO;

  491.         codec_id = AV_CODEC_ID_VC1;

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

  493.         // check dvd audio substream type

  494.         type = AVMEDIA_TYPE_AUDIO;

  495.         switch (dvdaudio_substream_type & 0xe0) {

  496.         case 0xa0:

  497.             codec_id = AV_CODEC_ID_PCM_DVD;

  498.             break;

  499.         case 0x80:

  500.             if ((dvdaudio_substream_type & 0xf8) == 0x88)

  501.                 codec_id = AV_CODEC_ID_DTS;

  502.             else

  503.                 codec_id = AV_CODEC_ID_AC3;

  504.             break;

  505.         default:

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

  507.             goto skip;

  508.         }

  509.     } else {

  510. skip:

  511.         /* skip packet */

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

  513.         goto redo;

  514.     }

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

  516.     st = avformat_new_stream(s, NULL);

  517.     if (!st)

  518.         goto skip;

  519.     st->id                = startcode;

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

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

  522.     st->need_parsing      = AVSTREAM_PARSE_FULL;

  523. 

  524. found:

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

  526.         goto skip;

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

  528. 

  529.     pkt->pts          = pts;

  530.     pkt->dts          = dts;

  531.     pkt->pos          = dummy_pos;

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

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

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

  535.             pkt->size);

  536. 

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

  538. }

  539. 

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

  541.                                int64_t *ppos, int64_t pos_limit)

  542. {

  543.     int len, startcode;

  544.     int64_t pos, pts, dts;

  545. 

  546.     pos = *ppos;

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

  548.         return AV_NOPTS_VALUE;

  549. 

  550.     for (;;) {

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

  552.         if (len < 0) {

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

  554.             return AV_NOPTS_VALUE;

  555.         }

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

  557.             dts != AV_NOPTS_VALUE) {

  558.             break;

  559.         }

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

  561.     }

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

  563.             pos, dts, dts / 90000.0);

  564.     *ppos = pos;

  565.     return dts;

  566. }

  567. 

  568. AVInputFormat ff_mpegps_demuxer = {

  569.     .name           = "mpeg",

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

  571.     .priv_data_size = sizeof(MpegDemuxContext),

  572.     .read_probe     = mpegps_probe,

  573.     .read_header    = mpegps_read_header,

  574.     .read_packet    = mpegps_read_packet,

  575.     .read_timestamp = mpegps_read_dts,

  576.     .flags          = AVFMT_SHOW_IDS | AVFMT_TS_DISCONT,

  577. };