Libav 0.7.1
libavformat/mpeg.c
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00001 /*
00002  * MPEG1/2 demuxer
00003  * Copyright (c) 2000, 2001, 2002 Fabrice Bellard
00004  *
00005  * This file is part of Libav.
00006  *
00007  * Libav is free software; you can redistribute it and/or
00008  * modify it under the terms of the GNU Lesser General Public
00009  * License as published by the Free Software Foundation; either
00010  * version 2.1 of the License, or (at your option) any later version.
00011  *
00012  * Libav is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00015  * Lesser General Public License for more details.
00016  *
00017  * You should have received a copy of the GNU Lesser General Public
00018  * License along with Libav; if not, write to the Free Software
00019  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00020  */
00021 
00022 #include "avformat.h"
00023 #include "internal.h"
00024 #include "mpeg.h"
00025 
00026 #undef NDEBUG
00027 #include <assert.h>
00028 
00029 /*********************************************/
00030 /* demux code */
00031 
00032 #define MAX_SYNC_SIZE 100000
00033 
00034 static int check_pes(uint8_t *p, uint8_t *end){
00035     int pes1;
00036     int pes2=      (p[3] & 0xC0) == 0x80
00037                 && (p[4] & 0xC0) != 0x40
00038                 &&((p[4] & 0xC0) == 0x00 || (p[4]&0xC0)>>2 == (p[6]&0xF0));
00039 
00040     for(p+=3; p<end && *p == 0xFF; p++);
00041     if((*p&0xC0) == 0x40) p+=2;
00042     if((*p&0xF0) == 0x20){
00043         pes1= p[0]&p[2]&p[4]&1;
00044     }else if((*p&0xF0) == 0x30){
00045         pes1= p[0]&p[2]&p[4]&p[5]&p[7]&p[9]&1;
00046     }else
00047         pes1 = *p == 0x0F;
00048 
00049     return pes1||pes2;
00050 }
00051 
00052 static int mpegps_probe(AVProbeData *p)
00053 {
00054     uint32_t code= -1;
00055     int sys=0, pspack=0, priv1=0, vid=0, audio=0, invalid=0;
00056     int i;
00057     int score=0;
00058 
00059     for(i=0; i<p->buf_size; i++){
00060         code = (code<<8) + p->buf[i];
00061         if ((code & 0xffffff00) == 0x100) {
00062             int len= p->buf[i+1] << 8 | p->buf[i+2];
00063             int pes= check_pes(p->buf+i, p->buf+p->buf_size);
00064 
00065             if(code == SYSTEM_HEADER_START_CODE) sys++;
00066             else if(code == PACK_START_CODE)     pspack++;
00067             else if((code & 0xf0) == VIDEO_ID &&  pes) vid++;
00068             // skip pes payload to avoid start code emulation for private
00069             // and audio streams
00070             else if((code & 0xe0) == AUDIO_ID &&  pes) {audio++; i+=len;}
00071             else if(code == PRIVATE_STREAM_1  &&  pes) {priv1++; i+=len;}
00072 
00073             else if((code & 0xf0) == VIDEO_ID && !pes) invalid++;
00074             else if((code & 0xe0) == AUDIO_ID && !pes) invalid++;
00075             else if(code == PRIVATE_STREAM_1  && !pes) invalid++;
00076         }
00077     }
00078 
00079     if(vid+audio > invalid)     /* invalid VDR files nd short PES streams */
00080         score= AVPROBE_SCORE_MAX/4;
00081 
00082 //av_log(NULL, AV_LOG_ERROR, "%d %d %d %d %d %d len:%d\n", sys, priv1, pspack,vid, audio, invalid, p->buf_size);
00083     if(sys>invalid && sys*9 <= pspack*10)
00084         return pspack > 2 ? AVPROBE_SCORE_MAX/2+2 : AVPROBE_SCORE_MAX/4; // +1 for .mpg
00085     if(pspack > invalid && (priv1+vid+audio)*10 >= pspack*9)
00086         return pspack > 2 ? AVPROBE_SCORE_MAX/2+2 : AVPROBE_SCORE_MAX/4; // +1 for .mpg
00087     if((!!vid ^ !!audio) && (audio > 4 || vid > 1) && !sys && !pspack && p->buf_size>2048 && vid + audio > invalid) /* PES stream */
00088         return (audio > 12 || vid > 3) ? AVPROBE_SCORE_MAX/2+2 : AVPROBE_SCORE_MAX/4;
00089 
00090     //02-Penguin.flac has sys:0 priv1:0 pspack:0 vid:0 audio:1
00091     //mp3_misidentified_2.mp3 has sys:0 priv1:0 pspack:0 vid:0 audio:6
00092     return score;
00093 }
00094 
00095 
00096 typedef struct MpegDemuxContext {
00097     int32_t header_state;
00098     unsigned char psm_es_type[256];
00099     int sofdec;
00100 } MpegDemuxContext;
00101 
00102 static int mpegps_read_header(AVFormatContext *s,
00103                               AVFormatParameters *ap)
00104 {
00105     MpegDemuxContext *m = s->priv_data;
00106     const char *sofdec = "Sofdec";
00107     int v, i = 0;
00108 
00109     m->header_state = 0xff;
00110     s->ctx_flags |= AVFMTCTX_NOHEADER;
00111 
00112     m->sofdec = -1;
00113     do {
00114         v = avio_r8(s->pb);
00115         m->header_state = m->header_state << 8 | v;
00116         m->sofdec++;
00117     } while (v == sofdec[i] && i++ < 6);
00118 
00119     m->sofdec = (m->sofdec == 6) ? 1 : 0;
00120 
00121     /* no need to do more */
00122     return 0;
00123 }
00124 
00125 static int64_t get_pts(AVIOContext *pb, int c)
00126 {
00127     uint8_t buf[5];
00128 
00129     buf[0] = c<0 ? avio_r8(pb) : c;
00130     avio_read(pb, buf+1, 4);
00131 
00132     return ff_parse_pes_pts(buf);
00133 }
00134 
00135 static int find_next_start_code(AVIOContext *pb, int *size_ptr,
00136                                 int32_t *header_state)
00137 {
00138     unsigned int state, v;
00139     int val, n;
00140 
00141     state = *header_state;
00142     n = *size_ptr;
00143     while (n > 0) {
00144         if (pb->eof_reached)
00145             break;
00146         v = avio_r8(pb);
00147         n--;
00148         if (state == 0x000001) {
00149             state = ((state << 8) | v) & 0xffffff;
00150             val = state;
00151             goto found;
00152         }
00153         state = ((state << 8) | v) & 0xffffff;
00154     }
00155     val = -1;
00156  found:
00157     *header_state = state;
00158     *size_ptr = n;
00159     return val;
00160 }
00161 
00162 #if 0 /* unused, remove? */
00163 /* XXX: optimize */
00164 static int find_prev_start_code(AVIOContext *pb, int *size_ptr)
00165 {
00166     int64_t pos, pos_start;
00167     int max_size, start_code;
00168 
00169     max_size = *size_ptr;
00170     pos_start = avio_tell(pb);
00171 
00172     /* in order to go faster, we fill the buffer */
00173     pos = pos_start - 16386;
00174     if (pos < 0)
00175         pos = 0;
00176     avio_seek(pb, pos, SEEK_SET);
00177     avio_r8(pb);
00178 
00179     pos = pos_start;
00180     for(;;) {
00181         pos--;
00182         if (pos < 0 || (pos_start - pos) >= max_size) {
00183             start_code = -1;
00184             goto the_end;
00185         }
00186         avio_seek(pb, pos, SEEK_SET);
00187         start_code = avio_rb32(pb);
00188         if ((start_code & 0xffffff00) == 0x100)
00189             break;
00190     }
00191  the_end:
00192     *size_ptr = pos_start - pos;
00193     return start_code;
00194 }
00195 #endif
00196 
00203 static long mpegps_psm_parse(MpegDemuxContext *m, AVIOContext *pb)
00204 {
00205     int psm_length, ps_info_length, es_map_length;
00206 
00207     psm_length = avio_rb16(pb);
00208     avio_r8(pb);
00209     avio_r8(pb);
00210     ps_info_length = avio_rb16(pb);
00211 
00212     /* skip program_stream_info */
00213     avio_skip(pb, ps_info_length);
00214     es_map_length = avio_rb16(pb);
00215 
00216     /* at least one es available? */
00217     while (es_map_length >= 4){
00218         unsigned char type      = avio_r8(pb);
00219         unsigned char es_id     = avio_r8(pb);
00220         uint16_t es_info_length = avio_rb16(pb);
00221         /* remember mapping from stream id to stream type */
00222         m->psm_es_type[es_id] = type;
00223         /* skip program_stream_info */
00224         avio_skip(pb, es_info_length);
00225         es_map_length -= 4 + es_info_length;
00226     }
00227     avio_rb32(pb); /* crc32 */
00228     return 2 + psm_length;
00229 }
00230 
00231 /* read the next PES header. Return its position in ppos
00232    (if not NULL), and its start code, pts and dts.
00233  */
00234 static int mpegps_read_pes_header(AVFormatContext *s,
00235                                   int64_t *ppos, int *pstart_code,
00236                                   int64_t *ppts, int64_t *pdts)
00237 {
00238     MpegDemuxContext *m = s->priv_data;
00239     int len, size, startcode, c, flags, header_len;
00240     int pes_ext, ext2_len, id_ext, skip;
00241     int64_t pts, dts;
00242     int64_t last_sync= avio_tell(s->pb);
00243 
00244  error_redo:
00245         avio_seek(s->pb, last_sync, SEEK_SET);
00246  redo:
00247         /* next start code (should be immediately after) */
00248         m->header_state = 0xff;
00249         size = MAX_SYNC_SIZE;
00250         startcode = find_next_start_code(s->pb, &size, &m->header_state);
00251         last_sync = avio_tell(s->pb);
00252     //printf("startcode=%x pos=0x%"PRIx64"\n", startcode, avio_tell(s->pb));
00253     if (startcode < 0){
00254         if(s->pb->eof_reached)
00255             return AVERROR_EOF;
00256         //FIXME we should remember header_state
00257         return AVERROR(EAGAIN);
00258     }
00259 
00260     if (startcode == PACK_START_CODE)
00261         goto redo;
00262     if (startcode == SYSTEM_HEADER_START_CODE)
00263         goto redo;
00264     if (startcode == PADDING_STREAM) {
00265         avio_skip(s->pb, avio_rb16(s->pb));
00266         goto redo;
00267     }
00268     if (startcode == PRIVATE_STREAM_2) {
00269         len = avio_rb16(s->pb);
00270         if (!m->sofdec) {
00271             while (len-- >= 6) {
00272                 if (avio_r8(s->pb) == 'S') {
00273                     uint8_t buf[5];
00274                     avio_read(s->pb, buf, sizeof(buf));
00275                     m->sofdec = !memcmp(buf, "ofdec", 5);
00276                     len -= sizeof(buf);
00277                     break;
00278                 }
00279             }
00280             m->sofdec -= !m->sofdec;
00281         }
00282         avio_skip(s->pb, len);
00283         goto redo;
00284     }
00285     if (startcode == PROGRAM_STREAM_MAP) {
00286         mpegps_psm_parse(m, s->pb);
00287         goto redo;
00288     }
00289 
00290     /* find matching stream */
00291     if (!((startcode >= 0x1c0 && startcode <= 0x1df) ||
00292           (startcode >= 0x1e0 && startcode <= 0x1ef) ||
00293           (startcode == 0x1bd) || (startcode == 0x1fd)))
00294         goto redo;
00295     if (ppos) {
00296         *ppos = avio_tell(s->pb) - 4;
00297     }
00298     len = avio_rb16(s->pb);
00299     pts =
00300     dts = AV_NOPTS_VALUE;
00301     /* stuffing */
00302     for(;;) {
00303         if (len < 1)
00304             goto error_redo;
00305         c = avio_r8(s->pb);
00306         len--;
00307         /* XXX: for mpeg1, should test only bit 7 */
00308         if (c != 0xff)
00309             break;
00310     }
00311     if ((c & 0xc0) == 0x40) {
00312         /* buffer scale & size */
00313         avio_r8(s->pb);
00314         c = avio_r8(s->pb);
00315         len -= 2;
00316     }
00317     if ((c & 0xe0) == 0x20) {
00318         dts = pts = get_pts(s->pb, c);
00319         len -= 4;
00320         if (c & 0x10){
00321             dts = get_pts(s->pb, -1);
00322             len -= 5;
00323         }
00324     } else if ((c & 0xc0) == 0x80) {
00325         /* mpeg 2 PES */
00326 #if 0 /* some streams have this field set for no apparent reason */
00327         if ((c & 0x30) != 0) {
00328             /* Encrypted multiplex not handled */
00329             goto redo;
00330         }
00331 #endif
00332         flags = avio_r8(s->pb);
00333         header_len = avio_r8(s->pb);
00334         len -= 2;
00335         if (header_len > len)
00336             goto error_redo;
00337         len -= header_len;
00338         if (flags & 0x80) {
00339             dts = pts = get_pts(s->pb, -1);
00340             header_len -= 5;
00341             if (flags & 0x40) {
00342                 dts = get_pts(s->pb, -1);
00343                 header_len -= 5;
00344             }
00345         }
00346         if (flags & 0x3f && header_len == 0){
00347             flags &= 0xC0;
00348             av_log(s, AV_LOG_WARNING, "Further flags set but no bytes left\n");
00349         }
00350         if (flags & 0x01) { /* PES extension */
00351             pes_ext = avio_r8(s->pb);
00352             header_len--;
00353             /* Skip PES private data, program packet sequence counter and P-STD buffer */
00354             skip = (pes_ext >> 4) & 0xb;
00355             skip += skip & 0x9;
00356             if (pes_ext & 0x40 || skip > header_len){
00357                 av_log(s, AV_LOG_WARNING, "pes_ext %X is invalid\n", pes_ext);
00358                 pes_ext=skip=0;
00359             }
00360             avio_skip(s->pb, skip);
00361             header_len -= skip;
00362 
00363             if (pes_ext & 0x01) { /* PES extension 2 */
00364                 ext2_len = avio_r8(s->pb);
00365                 header_len--;
00366                 if ((ext2_len & 0x7f) > 0) {
00367                     id_ext = avio_r8(s->pb);
00368                     if ((id_ext & 0x80) == 0)
00369                         startcode = ((startcode & 0xff) << 8) | id_ext;
00370                     header_len--;
00371                 }
00372             }
00373         }
00374         if(header_len < 0)
00375             goto error_redo;
00376         avio_skip(s->pb, header_len);
00377     }
00378     else if( c!= 0xf )
00379         goto redo;
00380 
00381     if (startcode == PRIVATE_STREAM_1 && !m->psm_es_type[startcode & 0xff]) {
00382         startcode = avio_r8(s->pb);
00383         len--;
00384         if (startcode >= 0x80 && startcode <= 0xcf) {
00385             /* audio: skip header */
00386             avio_r8(s->pb);
00387             avio_r8(s->pb);
00388             avio_r8(s->pb);
00389             len -= 3;
00390             if (startcode >= 0xb0 && startcode <= 0xbf) {
00391                 /* MLP/TrueHD audio has a 4-byte header */
00392                 avio_r8(s->pb);
00393                 len--;
00394             }
00395         }
00396     }
00397     if(len<0)
00398         goto error_redo;
00399     if(dts != AV_NOPTS_VALUE && ppos){
00400         int i;
00401         for(i=0; i<s->nb_streams; i++){
00402             if(startcode == s->streams[i]->id &&
00403                s->pb->seekable /* index useless on streams anyway */) {
00404                 ff_reduce_index(s, i);
00405                 av_add_index_entry(s->streams[i], *ppos, dts, 0, 0, AVINDEX_KEYFRAME /* FIXME keyframe? */);
00406             }
00407         }
00408     }
00409 
00410     *pstart_code = startcode;
00411     *ppts = pts;
00412     *pdts = dts;
00413     return len;
00414 }
00415 
00416 static int mpegps_read_packet(AVFormatContext *s,
00417                               AVPacket *pkt)
00418 {
00419     MpegDemuxContext *m = s->priv_data;
00420     AVStream *st;
00421     int len, startcode, i, es_type, ret;
00422     enum CodecID codec_id = CODEC_ID_NONE;
00423     enum AVMediaType type;
00424     int64_t pts, dts, dummy_pos; //dummy_pos is needed for the index building to work
00425     uint8_t av_uninit(dvdaudio_substream_type);
00426 
00427  redo:
00428     len = mpegps_read_pes_header(s, &dummy_pos, &startcode, &pts, &dts);
00429     if (len < 0)
00430         return len;
00431 
00432     if(startcode == 0x1bd) {
00433         dvdaudio_substream_type = avio_r8(s->pb);
00434         avio_skip(s->pb, 3);
00435         len -= 4;
00436     }
00437 
00438     /* now find stream */
00439     for(i=0;i<s->nb_streams;i++) {
00440         st = s->streams[i];
00441         if (st->id == startcode)
00442             goto found;
00443     }
00444 
00445     es_type = m->psm_es_type[startcode & 0xff];
00446     if(es_type > 0 && es_type != STREAM_TYPE_PRIVATE_DATA){
00447         if(es_type == STREAM_TYPE_VIDEO_MPEG1){
00448             codec_id = CODEC_ID_MPEG2VIDEO;
00449             type = AVMEDIA_TYPE_VIDEO;
00450         } else if(es_type == STREAM_TYPE_VIDEO_MPEG2){
00451             codec_id = CODEC_ID_MPEG2VIDEO;
00452             type = AVMEDIA_TYPE_VIDEO;
00453         } else if(es_type == STREAM_TYPE_AUDIO_MPEG1 ||
00454                   es_type == STREAM_TYPE_AUDIO_MPEG2){
00455             codec_id = CODEC_ID_MP3;
00456             type = AVMEDIA_TYPE_AUDIO;
00457         } else if(es_type == STREAM_TYPE_AUDIO_AAC){
00458             codec_id = CODEC_ID_AAC;
00459             type = AVMEDIA_TYPE_AUDIO;
00460         } else if(es_type == STREAM_TYPE_VIDEO_MPEG4){
00461             codec_id = CODEC_ID_MPEG4;
00462             type = AVMEDIA_TYPE_VIDEO;
00463         } else if(es_type == STREAM_TYPE_VIDEO_H264){
00464             codec_id = CODEC_ID_H264;
00465             type = AVMEDIA_TYPE_VIDEO;
00466         } else if(es_type == STREAM_TYPE_AUDIO_AC3){
00467             codec_id = CODEC_ID_AC3;
00468             type = AVMEDIA_TYPE_AUDIO;
00469         } else {
00470             goto skip;
00471         }
00472     } else if (startcode >= 0x1e0 && startcode <= 0x1ef) {
00473         static const unsigned char avs_seqh[4] = { 0, 0, 1, 0xb0 };
00474         unsigned char buf[8];
00475         avio_read(s->pb, buf, 8);
00476         avio_seek(s->pb, -8, SEEK_CUR);
00477         if(!memcmp(buf, avs_seqh, 4) && (buf[6] != 0 || buf[7] != 1))
00478             codec_id = CODEC_ID_CAVS;
00479         else
00480             codec_id = CODEC_ID_PROBE;
00481         type = AVMEDIA_TYPE_VIDEO;
00482     } else if (startcode >= 0x1c0 && startcode <= 0x1df) {
00483         type = AVMEDIA_TYPE_AUDIO;
00484         codec_id = m->sofdec > 0 ? CODEC_ID_ADPCM_ADX : CODEC_ID_MP2;
00485     } else if (startcode >= 0x80 && startcode <= 0x87) {
00486         type = AVMEDIA_TYPE_AUDIO;
00487         codec_id = CODEC_ID_AC3;
00488     } else if (  ( startcode >= 0x88 && startcode <= 0x8f)
00489                ||( startcode >= 0x98 && startcode <= 0x9f)) {
00490         /* 0x90 - 0x97 is reserved for SDDS in DVD specs */
00491         type = AVMEDIA_TYPE_AUDIO;
00492         codec_id = CODEC_ID_DTS;
00493     } else if (startcode >= 0xa0 && startcode <= 0xaf) {
00494         type = AVMEDIA_TYPE_AUDIO;
00495         /* 16 bit form will be handled as CODEC_ID_PCM_S16BE */
00496         codec_id = CODEC_ID_PCM_DVD;
00497     } else if (startcode >= 0xb0 && startcode <= 0xbf) {
00498         type = AVMEDIA_TYPE_AUDIO;
00499         codec_id = CODEC_ID_TRUEHD;
00500     } else if (startcode >= 0xc0 && startcode <= 0xcf) {
00501         /* Used for both AC-3 and E-AC-3 in EVOB files */
00502         type = AVMEDIA_TYPE_AUDIO;
00503         codec_id = CODEC_ID_AC3;
00504     } else if (startcode >= 0x20 && startcode <= 0x3f) {
00505         type = AVMEDIA_TYPE_SUBTITLE;
00506         codec_id = CODEC_ID_DVD_SUBTITLE;
00507     } else if (startcode >= 0xfd55 && startcode <= 0xfd5f) {
00508         type = AVMEDIA_TYPE_VIDEO;
00509         codec_id = CODEC_ID_VC1;
00510     } else if (startcode == 0x1bd) {
00511         // check dvd audio substream type
00512         type = AVMEDIA_TYPE_AUDIO;
00513         switch(dvdaudio_substream_type & 0xe0) {
00514         case 0xa0:  codec_id = CODEC_ID_PCM_DVD;
00515                     break;
00516         case 0x80:  if((dvdaudio_substream_type & 0xf8) == 0x88)
00517                          codec_id = CODEC_ID_DTS;
00518                     else codec_id = CODEC_ID_AC3;
00519                     break;
00520         default:    av_log(s, AV_LOG_ERROR, "Unknown 0x1bd sub-stream\n");
00521                     goto skip;
00522         }
00523     } else {
00524     skip:
00525         /* skip packet */
00526         avio_skip(s->pb, len);
00527         goto redo;
00528     }
00529     /* no stream found: add a new stream */
00530     st = av_new_stream(s, startcode);
00531     if (!st)
00532         goto skip;
00533     st->codec->codec_type = type;
00534     st->codec->codec_id = codec_id;
00535     if (codec_id != CODEC_ID_PCM_S16BE)
00536         st->need_parsing = AVSTREAM_PARSE_FULL;
00537  found:
00538     if(st->discard >= AVDISCARD_ALL)
00539         goto skip;
00540     if ((startcode >= 0xa0 && startcode <= 0xaf) ||
00541         (startcode == 0x1bd && ((dvdaudio_substream_type & 0xe0) == 0xa0))) {
00542         int b1, freq;
00543 
00544         /* for LPCM, we just skip the header and consider it is raw
00545            audio data */
00546         if (len <= 3)
00547             goto skip;
00548         avio_r8(s->pb); /* emphasis (1), muse(1), reserved(1), frame number(5) */
00549         b1 = avio_r8(s->pb); /* quant (2), freq(2), reserved(1), channels(3) */
00550         avio_r8(s->pb); /* dynamic range control (0x80 = off) */
00551         len -= 3;
00552         freq = (b1 >> 4) & 3;
00553         st->codec->sample_rate = lpcm_freq_tab[freq];
00554         st->codec->channels = 1 + (b1 & 7);
00555         st->codec->bits_per_coded_sample = 16 + ((b1 >> 6) & 3) * 4;
00556         st->codec->bit_rate = st->codec->channels *
00557                               st->codec->sample_rate *
00558                               st->codec->bits_per_coded_sample;
00559         if (st->codec->bits_per_coded_sample == 16)
00560             st->codec->codec_id = CODEC_ID_PCM_S16BE;
00561         else if (st->codec->bits_per_coded_sample == 28)
00562             return AVERROR(EINVAL);
00563     }
00564     ret = av_get_packet(s->pb, pkt, len);
00565     pkt->pts = pts;
00566     pkt->dts = dts;
00567     pkt->pos = dummy_pos;
00568     pkt->stream_index = st->index;
00569     av_dlog(s, "%d: pts=%0.3f dts=%0.3f size=%d\n",
00570             pkt->stream_index, pkt->pts / 90000.0, pkt->dts / 90000.0,
00571             pkt->size);
00572 
00573     return (ret < 0) ? ret : 0;
00574 }
00575 
00576 static int64_t mpegps_read_dts(AVFormatContext *s, int stream_index,
00577                                int64_t *ppos, int64_t pos_limit)
00578 {
00579     int len, startcode;
00580     int64_t pos, pts, dts;
00581 
00582     pos = *ppos;
00583     if (avio_seek(s->pb, pos, SEEK_SET) < 0)
00584         return AV_NOPTS_VALUE;
00585 
00586     for(;;) {
00587         len = mpegps_read_pes_header(s, &pos, &startcode, &pts, &dts);
00588         if (len < 0) {
00589             av_dlog(s, "none (ret=%d)\n", len);
00590             return AV_NOPTS_VALUE;
00591         }
00592         if (startcode == s->streams[stream_index]->id &&
00593             dts != AV_NOPTS_VALUE) {
00594             break;
00595         }
00596         avio_skip(s->pb, len);
00597     }
00598     av_dlog(s, "pos=0x%"PRIx64" dts=0x%"PRIx64" %0.3f\n",
00599             pos, dts, dts / 90000.0);
00600     *ppos = pos;
00601     return dts;
00602 }
00603 
00604 AVInputFormat ff_mpegps_demuxer = {
00605     "mpeg",
00606     NULL_IF_CONFIG_SMALL("MPEG-PS format"),
00607     sizeof(MpegDemuxContext),
00608     mpegps_probe,
00609     mpegps_read_header,
00610     mpegps_read_packet,
00611     NULL,
00612     NULL, //mpegps_read_seek,
00613     mpegps_read_dts,
00614     .flags = AVFMT_SHOW_IDS|AVFMT_TS_DISCONT,
00615 };