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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 check_pes(uint8_t *p, uint8_t *end){

  36.     int pes1;

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

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

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

  40. 

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

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

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

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

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

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

  47.     }else

  48.         pes1 = *p == 0x0F;

  49. 

  50.     return pes1||pes2;

  51. }

  52. 

  53. static int mpegps_probe(AVProbeData *p)

  54. {

  55.     uint32_t code= -1;

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

  57.     int i;

  58.     int score=0;

  59. 

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

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

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

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

  64. 

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

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

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

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

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

  70. 

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

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

  73.         }

  74.     }

  75. 

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

  77.         score= AVPROBE_SCORE_MAX/4;

  78. 

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

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

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

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

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

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

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

  86. 

  87.     //02-Penguin.flac has sys:0 priv1:0 pspack:0 vid:0 audio:1

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

  89.     return score;

  90. }

  91. 

  92. 

  93. typedef struct MpegDemuxContext {

  94.     int32_t header_state;

  95.     unsigned char psm_es_type[256];

  96.     int sofdec;

  97. } MpegDemuxContext;

  98. 

  99. static int mpegps_read_header(AVFormatContext *s,

  100.                               AVFormatParameters *ap)

  101. {

  102.     MpegDemuxContext *m = s->priv_data;

  103.     const char *sofdec = "Sofdec";

  104.     int v, i = 0;

  105. 

  106.     m->header_state = 0xff;

  107.     s->ctx_flags |= AVFMTCTX_NOHEADER;

  108. 

  109.     m->sofdec = -1;

  110.     do {

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

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

  113.         m->sofdec++;

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

  115. 

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

  117. 

  118.     /* no need to do more */

  119.     return 0;

  120. }

  121. 

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

  123. {

  124.     uint8_t buf[5];

  125. 

  126.     buf[0] = c<0 ? get_byte(pb) : c;

  127.     get_buffer(pb, buf+1, 4);

  128. 

  129.     return ff_parse_pes_pts(buf);

  130. }

  131. 

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

  133.                                 int32_t *header_state)

  134. {

  135.     unsigned int state, v;

  136.     int val, n;

  137. 

  138.     state = *header_state;

  139.     n = *size_ptr;

  140.     while (n > 0) {

  141.         if (url_feof(pb))

  142.             break;

  143.         v = get_byte(pb);

  144.         n--;

  145.         if (state == 0x000001) {

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

  147.             val = state;

  148.             goto found;

  149.         }

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

  151.     }

  152.     val = -1;

  153.  found:

  154.     *header_state = state;

  155.     *size_ptr = n;

  156.     return val;

  157. }

  158. 

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

  160. /* XXX: optimize */

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

  162. {

  163.     int64_t pos, pos_start;

  164.     int max_size, start_code;

  165. 

  166.     max_size = *size_ptr;

  167.     pos_start = url_ftell(pb);

  168. 

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

  170.     pos = pos_start - 16386;

  171.     if (pos < 0)

  172.         pos = 0;

  173.     url_fseek(pb, pos, SEEK_SET);

  174.     get_byte(pb);

  175. 

  176.     pos = pos_start;

  177.     for(;;) {

  178.         pos--;

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

  180.             start_code = -1;

  181.             goto the_end;

  182.         }

  183.         url_fseek(pb, pos, SEEK_SET);

  184.         start_code = get_be32(pb);

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

  186.             break;

  187.     }

  188.  the_end:

  189.     *size_ptr = pos_start - pos;

  190.     return start_code;

  191. }

  192. #endif

  193. 

  194. /**

  195.  * Extracts stream types from a program stream map

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

  197.  *

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

  199.  */

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

  201. {

  202.     int psm_length, ps_info_length, es_map_length;

  203. 

  204.     psm_length = get_be16(pb);

  205.     get_byte(pb);

  206.     get_byte(pb);

  207.     ps_info_length = get_be16(pb);

  208. 

  209.     /* skip program_stream_info */

  210.     url_fskip(pb, ps_info_length);

  211.     es_map_length = get_be16(pb);

  212. 

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

  214.     while (es_map_length >= 4){

  215.         unsigned char type      = get_byte(pb);

  216.         unsigned char es_id     = get_byte(pb);

  217.         uint16_t es_info_length = get_be16(pb);

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

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

  220.         /* skip program_stream_info */

  221.         url_fskip(pb, es_info_length);

  222.         es_map_length -= 4 + es_info_length;

  223.     }

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

  225.     return 2 + psm_length;

  226. }

  227. 

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

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

  230.  */

  231. static int mpegps_read_pes_header(AVFormatContext *s,

  232.                                   int64_t *ppos, int *pstart_code,

  233.                                   int64_t *ppts, int64_t *pdts)

  234. {

  235.     MpegDemuxContext *m = s->priv_data;

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

  237.     int pes_ext, ext2_len, id_ext, skip;

  238.     int64_t pts, dts;

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

  240. 

  241.  error_redo:

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

  243.  redo:

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

  245.         m->header_state = 0xff;

  246.         size = MAX_SYNC_SIZE;

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

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

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

  250.     if (startcode < 0){

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

  252.             return AVERROR_EOF;

  253.         //FIXME we should remember header_state

  254.         return AVERROR(EAGAIN);

  255.     }

  256. 

  257.     if (startcode == PACK_START_CODE)

  258.         goto redo;

  259.     if (startcode == SYSTEM_HEADER_START_CODE)

  260.         goto redo;

  261.     if (startcode == PADDING_STREAM) {

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

  263.         goto redo;

  264.     }

  265.     if (startcode == PRIVATE_STREAM_2) {

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

  267.         if (!m->sofdec) {

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

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

  270.                     uint8_t buf[5];

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

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

  273.                     len -= sizeof(buf);

  274.                     break;

  275.                 }

  276.             }

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

  278.         }

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

  280.         goto redo;

  281.     }

  282.     if (startcode == PROGRAM_STREAM_MAP) {

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

  284.         goto redo;

  285.     }

  286. 

  287.     /* find matching stream */

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

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

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

  291.         goto redo;

  292.     if (ppos) {

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

  294.     }

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

  296.     pts =

  297.     dts = AV_NOPTS_VALUE;

  298.     /* stuffing */

  299.     for(;;) {

  300.         if (len < 1)

  301.             goto error_redo;

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

  303.         len--;

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

  305.         if (c != 0xff)

  306.             break;

  307.     }

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

  309.         /* buffer scale & size */

  310.         get_byte(s->pb);

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

  312.         len -= 2;

  313.     }

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

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

  316.         len -= 4;

  317.         if (c & 0x10){

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

  319.             len -= 5;

  320.         }

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

  322.         /* mpeg 2 PES */

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

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

  325.             /* Encrypted multiplex not handled */

  326.             goto redo;

  327.         }

  328. #endif

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

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

  331.         len -= 2;

  332.         if (header_len > len)

  333.             goto error_redo;

  334.         len -= header_len;

  335.         if (flags & 0x80) {

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

  337.             header_len -= 5;

  338.             if (flags & 0x40) {

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

  340.                 header_len -= 5;

  341.             }

  342.         }

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

  344.             flags &= 0xC0;

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

  346.         }

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

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

  349.             header_len--;

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

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

  352.             skip += skip & 0x9;

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

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

  355.                 pes_ext=skip=0;

  356.             }

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

  358.             header_len -= skip;

  359. 

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

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

  362.                 header_len--;

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

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

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

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

  367.                     header_len--;

  368.                 }

  369.             }

  370.         }

  371.         if(header_len < 0)

  372.             goto error_redo;

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

  374.     }

  375.     else if( c!= 0xf )

  376.         goto redo;

  377. 

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

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

  380.         len--;

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

  382.             /* audio: skip header */

  383.             get_byte(s->pb);

  384.             get_byte(s->pb);

  385.             get_byte(s->pb);

  386.             len -= 3;

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

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

  389.                 get_byte(s->pb);

  390.                 len--;

  391.             }

  392.         }

  393.     }

  394.     if(len<0)

  395.         goto error_redo;

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

  397.         int i;

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

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

  400.                !url_is_streamed(s->pb) /* index useless on streams anyway */) {

  401.                 ff_reduce_index(s, i);

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

  403.             }

  404.         }

  405.     }

  406. 

  407.     *pstart_code = startcode;

  408.     *ppts = pts;

  409.     *pdts = dts;

  410.     return len;

  411. }

  412. 

  413. static int mpegps_read_packet(AVFormatContext *s,

  414.                               AVPacket *pkt)

  415. {

  416.     MpegDemuxContext *m = s->priv_data;

  417.     AVStream *st;

  418.     int len, startcode, i, es_type;

  419.     enum CodecID codec_id = CODEC_ID_NONE;

  420.     enum CodecType type;

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

  422.     uint8_t av_uninit(dvdaudio_substream_type);

  423. 

  424.  redo:

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

  426.     if (len < 0)

  427.         return len;

  428. 

  429.     if(startcode == 0x1bd) {

  430.         dvdaudio_substream_type = get_byte(s->pb);

  431.         url_fskip(s->pb, 3);

  432.         len -= 4;

  433.     }

  434. 

  435.     /* now find stream */

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

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

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

  439.             goto found;

  440.     }

  441. 

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

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

  444.         if(es_type == STREAM_TYPE_VIDEO_MPEG1){

  445.             codec_id = CODEC_ID_MPEG2VIDEO;

  446.             type = CODEC_TYPE_VIDEO;

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

  448.             codec_id = CODEC_ID_MPEG2VIDEO;

  449.             type = CODEC_TYPE_VIDEO;

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

  451.                   es_type == STREAM_TYPE_AUDIO_MPEG2){

  452.             codec_id = CODEC_ID_MP3;

  453.             type = CODEC_TYPE_AUDIO;

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

  455.             codec_id = CODEC_ID_AAC;

  456.             type = CODEC_TYPE_AUDIO;

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

  458.             codec_id = CODEC_ID_MPEG4;

  459.             type = CODEC_TYPE_VIDEO;

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

  461.             codec_id = CODEC_ID_H264;

  462.             type = CODEC_TYPE_VIDEO;

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

  464.             codec_id = CODEC_ID_AC3;

  465.             type = CODEC_TYPE_AUDIO;

  466.         } else {

  467.             goto skip;

  468.         }

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

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

  471.         unsigned char buf[8];

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

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

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

  475.             codec_id = CODEC_ID_CAVS;

  476.         else

  477.             codec_id = CODEC_ID_PROBE;

  478.         type = CODEC_TYPE_VIDEO;

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

  480.         type = CODEC_TYPE_AUDIO;

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

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

  483.         type = CODEC_TYPE_AUDIO;

  484.         codec_id = CODEC_ID_AC3;

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

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

  487.         /* 0x90 - 0x97 is reserved for SDDS in DVD specs */

  488.         type = CODEC_TYPE_AUDIO;

  489.         codec_id = CODEC_ID_DTS;

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

  491.         type = CODEC_TYPE_AUDIO;

  492.         /* 16 bit form will be handled as CODEC_ID_PCM_S16BE */

  493.         codec_id = CODEC_ID_PCM_DVD;

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

  495.         type = CODEC_TYPE_AUDIO;

  496.         codec_id = CODEC_ID_TRUEHD;

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

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

  499.         type = CODEC_TYPE_AUDIO;

  500.         codec_id = CODEC_ID_AC3;

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

  502.         type = CODEC_TYPE_SUBTITLE;

  503.         codec_id = CODEC_ID_DVD_SUBTITLE;

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

  505.         type = CODEC_TYPE_VIDEO;

  506.         codec_id = CODEC_ID_VC1;

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

  508.         // check dvd audio substream type

  509.         type = CODEC_TYPE_AUDIO;

  510.         switch(dvdaudio_substream_type & 0xe0) {

  511.         case 0xa0:  codec_id = CODEC_ID_PCM_DVD;

  512.                     break;

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

  514.                          codec_id = CODEC_ID_DTS;

  515.                     else codec_id = CODEC_ID_AC3;

  516.                     break;

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

  518.                     goto skip;

  519.         }

  520.     } else {

  521.     skip:

  522.         /* skip packet */

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

  524.         goto redo;

  525.     }

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

  527.     st = av_new_stream(s, startcode);

  528.     if (!st)

  529.         goto skip;

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

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

  532.     if (codec_id != CODEC_ID_PCM_S16BE)

  533.         st->need_parsing = AVSTREAM_PARSE_FULL;

  534.  found:

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

  536.         goto skip;

  537.     if ((startcode >= 0xa0 && startcode <= 0xaf) ||

  538.         (startcode == 0x1bd && ((dvdaudio_substream_type & 0xe0) == 0xa0))) {

  539.         int b1, freq;

  540. 

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

  542.            audio data */

  543.         if (len <= 3)

  544.             goto skip;

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

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

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

  548.         len -= 3;

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

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

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

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

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

  554.                               st->codec->sample_rate *

  555.                               st->codec->bits_per_coded_sample;

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

  557.             st->codec->codec_id = CODEC_ID_PCM_S16BE;

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

  559.             return AVERROR(EINVAL);

  560.     }

  561.     av_new_packet(pkt, len);

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

  563.     pkt->pts = pts;

  564.     pkt->dts = dts;

  565.     pkt->pos = dummy_pos;

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

  567. #if 0

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

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

  570. #endif

  571. 

  572.     return 0;

  573. }

  574. 

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

  576.                                int64_t *ppos, int64_t pos_limit)

  577. {

  578.     int len, startcode;

  579.     int64_t pos, pts, dts;

  580. 

  581.     pos = *ppos;

  582. #ifdef DEBUG_SEEK

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

  584. #endif

  585.     if (url_fseek(s->pb, pos, SEEK_SET) < 0)

  586.         return AV_NOPTS_VALUE;

  587. 

  588.     for(;;) {

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

  590.         if (len < 0) {

  591. #ifdef DEBUG_SEEK

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

  593. #endif

  594.             return AV_NOPTS_VALUE;

  595.         }

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

  597.             dts != AV_NOPTS_VALUE) {

  598.             break;

  599.         }

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

  601.     }

  602. #ifdef DEBUG_SEEK

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

  604. #endif

  605.     *ppos = pos;

  606.     return dts;

  607. }

  608. 

  609. AVInputFormat mpegps_demuxer = {

  610.     "mpeg",

  611.     NULL_IF_CONFIG_SMALL("MPEG-PS format"),

  612.     sizeof(MpegDemuxContext),

  613.     mpegps_probe,

  614.     mpegps_read_header,

  615.     mpegps_read_packet,

  616.     NULL,

  617.     NULL, //mpegps_read_seek,

  618.     mpegps_read_dts,

  619.     .flags = AVFMT_SHOW_IDS|AVFMT_TS_DISCONT,

  620. };