FFmpeg: libavformat/mpeg.c Source File

00001 /*
00002  * MPEG1/2 demuxer
00003  * Copyright (c) 2000, 2001, 2002 Fabrice Bellard
00004  *
00005  * This file is part of FFmpeg.
00006  *
00007  * FFmpeg 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  * FFmpeg 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 FFmpeg; 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 check_pack_header(const uint8_t *buf) {
00053     return (buf[1] & 0xC0) == 0x40 || (buf[1] & 0xF0) == 0x20;
00054 }
00055 
00056 static int mpegps_probe(AVProbeData *p)
00057 {
00058     uint32_t code= -1;
00059     int sys=0, pspack=0, priv1=0, vid=0, audio=0, invalid=0;
00060     int i;
00061     int score=0;
00062 
00063     for(i=0; i<p->buf_size; i++){
00064         code = (code<<8) + p->buf[i];
00065         if ((code & 0xffffff00) == 0x100) {
00066             int len= p->buf[i+1] << 8 | p->buf[i+2];
00067             int pes= check_pes(p->buf+i, p->buf+p->buf_size);
00068             int pack = check_pack_header(p->buf+i);
00069 
00070             if(code == SYSTEM_HEADER_START_CODE) sys++;
00071             else if(code == PACK_START_CODE && pack) pspack++;
00072             else if((code & 0xf0) == VIDEO_ID &&  pes) vid++;
00073             // skip pes payload to avoid start code emulation for private
00074             // and audio streams
00075             else if((code & 0xe0) == AUDIO_ID &&  pes) {audio++; i+=len;}
00076             else if(code == PRIVATE_STREAM_1  &&  pes) {priv1++; i+=len;}
00077             else if(code == 0x1fd             &&  pes) vid++; //VC1
00078 
00079             else if((code & 0xf0) == VIDEO_ID && !pes) invalid++;
00080             else if((code & 0xe0) == AUDIO_ID && !pes) invalid++;
00081             else if(code == PRIVATE_STREAM_1  && !pes) invalid++;
00082         }
00083     }
00084 
00085     if(vid+audio > invalid+1)     /* invalid VDR files nd short PES streams */
00086         score= AVPROBE_SCORE_MAX/4;
00087 
00088 //av_log(NULL, AV_LOG_ERROR, "%d %d %d %d %d %d len:%d\n", sys, priv1, pspack,vid, audio, invalid, p->buf_size);
00089     if(sys>invalid && sys*9 <= pspack*10)
00090         return pspack > 2 ? AVPROBE_SCORE_MAX/2+2 : AVPROBE_SCORE_MAX/4; // +1 for .mpg
00091     if(pspack > invalid && (priv1+vid+audio)*10 >= pspack*9)
00092         return pspack > 2 ? AVPROBE_SCORE_MAX/2+2 : AVPROBE_SCORE_MAX/4; // +1 for .mpg
00093     if((!!vid ^ !!audio) && (audio > 4 || vid > 1) && !sys && !pspack && p->buf_size>2048 && vid + audio > invalid) /* PES stream */
00094         return (audio > 12 || vid > 3) ? AVPROBE_SCORE_MAX/2+2 : AVPROBE_SCORE_MAX/4;
00095 
00096     //02-Penguin.flac has sys:0 priv1:0 pspack:0 vid:0 audio:1
00097     //mp3_misidentified_2.mp3 has sys:0 priv1:0 pspack:0 vid:0 audio:6
00098     return score;
00099 }
00100 
00101 
00102 typedef struct MpegDemuxContext {
00103     int32_t header_state;
00104     unsigned char psm_es_type[256];
00105     int sofdec;
00106 } MpegDemuxContext;
00107 
00108 static int mpegps_read_header(AVFormatContext *s,
00109                               AVFormatParameters *ap)
00110 {
00111     MpegDemuxContext *m = s->priv_data;
00112     const char *sofdec = "Sofdec";
00113     int v, i = 0;
00114     int64_t last_pos = avio_tell(s->pb);
00115 
00116     m->header_state = 0xff;
00117     s->ctx_flags |= AVFMTCTX_NOHEADER;
00118 
00119     m->sofdec = -1;
00120     do {
00121         v = avio_r8(s->pb);
00122         m->sofdec++;
00123     } while (v == sofdec[i] && i++ < 6);
00124 
00125     m->sofdec = (m->sofdec == 6) ? 1 : 0;
00126 
00127     if (!m->sofdec)
00128        avio_seek(s->pb, last_pos, SEEK_SET);
00129 
00130     /* no need to do more */
00131     return 0;
00132 }
00133 
00134 static int64_t get_pts(AVIOContext *pb, int c)
00135 {
00136     uint8_t buf[5];
00137 
00138     buf[0] = c<0 ? avio_r8(pb) : c;
00139     avio_read(pb, buf+1, 4);
00140 
00141     return ff_parse_pes_pts(buf);
00142 }
00143 
00144 static int find_next_start_code(AVIOContext *pb, int *size_ptr,
00145                                 int32_t *header_state)
00146 {
00147     unsigned int state, v;
00148     int val, n;
00149 
00150     state = *header_state;
00151     n = *size_ptr;
00152     while (n > 0) {
00153         if (url_feof(pb))
00154             break;
00155         v = avio_r8(pb);
00156         n--;
00157         if (state == 0x000001) {
00158             state = ((state << 8) | v) & 0xffffff;
00159             val = state;
00160             goto found;
00161         }
00162         state = ((state << 8) | v) & 0xffffff;
00163     }
00164     val = -1;
00165  found:
00166     *header_state = state;
00167     *size_ptr = n;
00168     return val;
00169 }
00170 
00171 #if 0 /* unused, remove? */
00172 /* XXX: optimize */
00173 static int find_prev_start_code(AVIOContext *pb, int *size_ptr)
00174 {
00175     int64_t pos, pos_start;
00176     int max_size, start_code;
00177 
00178     max_size = *size_ptr;
00179     pos_start = avio_tell(pb);
00180 
00181     /* in order to go faster, we fill the buffer */
00182     pos = pos_start - 16386;
00183     if (pos < 0)
00184         pos = 0;
00185     avio_seek(pb, pos, SEEK_SET);
00186     avio_r8(pb);
00187 
00188     pos = pos_start;
00189     for(;;) {
00190         pos--;
00191         if (pos < 0 || (pos_start - pos) >= max_size) {
00192             start_code = -1;
00193             goto the_end;
00194         }
00195         avio_seek(pb, pos, SEEK_SET);
00196         start_code = avio_rb32(pb);
00197         if ((start_code & 0xffffff00) == 0x100)
00198             break;
00199     }
00200  the_end:
00201     *size_ptr = pos_start - pos;
00202     return start_code;
00203 }
00204 #endif
00205 
00212 static long mpegps_psm_parse(MpegDemuxContext *m, AVIOContext *pb)
00213 {
00214     int psm_length, ps_info_length, es_map_length;
00215 
00216     psm_length = avio_rb16(pb);
00217     avio_r8(pb);
00218     avio_r8(pb);
00219     ps_info_length = avio_rb16(pb);
00220 
00221     /* skip program_stream_info */
00222     avio_skip(pb, ps_info_length);
00223     es_map_length = avio_rb16(pb);
00224 
00225     /* at least one es available? */
00226     while (es_map_length >= 4){
00227         unsigned char type      = avio_r8(pb);
00228         unsigned char es_id     = avio_r8(pb);
00229         uint16_t es_info_length = avio_rb16(pb);
00230         /* remember mapping from stream id to stream type */
00231         m->psm_es_type[es_id] = type;
00232         /* skip program_stream_info */
00233         avio_skip(pb, es_info_length);
00234         es_map_length -= 4 + es_info_length;
00235     }
00236     avio_rb32(pb); /* crc32 */
00237     return 2 + psm_length;
00238 }
00239 
00240 /* read the next PES header. Return its position in ppos
00241    (if not NULL), and its start code, pts and dts.
00242  */
00243 static int mpegps_read_pes_header(AVFormatContext *s,
00244                                   int64_t *ppos, int *pstart_code,
00245                                   int64_t *ppts, int64_t *pdts)
00246 {
00247     MpegDemuxContext *m = s->priv_data;
00248     int len, size, startcode, c, flags, header_len;
00249     int pes_ext, ext2_len, id_ext, skip;
00250     int64_t pts, dts;
00251     int64_t last_sync= avio_tell(s->pb);
00252 
00253  error_redo:
00254         avio_seek(s->pb, last_sync, SEEK_SET);
00255  redo:
00256         /* next start code (should be immediately after) */
00257         m->header_state = 0xff;
00258         size = MAX_SYNC_SIZE;
00259         startcode = find_next_start_code(s->pb, &size, &m->header_state);
00260         last_sync = avio_tell(s->pb);
00261     //printf("startcode=%x pos=0x%"PRIx64"\n", startcode, avio_tell(s->pb));
00262     if (startcode < 0){
00263         if(url_feof(s->pb))
00264             return AVERROR_EOF;
00265         //FIXME we should remember header_state
00266         return AVERROR(EAGAIN);
00267     }
00268 
00269     if (startcode == PACK_START_CODE)
00270         goto redo;
00271     if (startcode == SYSTEM_HEADER_START_CODE)
00272         goto redo;
00273     if (startcode == PADDING_STREAM) {
00274         avio_skip(s->pb, avio_rb16(s->pb));
00275         goto redo;
00276     }
00277     if (startcode == PRIVATE_STREAM_2) {
00278         len = avio_rb16(s->pb);
00279         if (!m->sofdec) {
00280             while (len-- >= 6) {
00281                 if (avio_r8(s->pb) == 'S') {
00282                     uint8_t buf[5];
00283                     avio_read(s->pb, buf, sizeof(buf));
00284                     m->sofdec = !memcmp(buf, "ofdec", 5);
00285                     len -= sizeof(buf);
00286                     break;
00287                 }
00288             }
00289             m->sofdec -= !m->sofdec;
00290         }
00291         avio_skip(s->pb, len);
00292         goto redo;
00293     }
00294     if (startcode == PROGRAM_STREAM_MAP) {
00295         mpegps_psm_parse(m, s->pb);
00296         goto redo;
00297     }
00298 
00299     /* find matching stream */
00300     if (!((startcode >= 0x1c0 && startcode <= 0x1df) ||
00301           (startcode >= 0x1e0 && startcode <= 0x1ef) ||
00302           (startcode == 0x1bd) || (startcode == 0x1fd)))
00303         goto redo;
00304     if (ppos) {
00305         *ppos = avio_tell(s->pb) - 4;
00306     }
00307     len = avio_rb16(s->pb);
00308     pts =
00309     dts = AV_NOPTS_VALUE;
00310     /* stuffing */
00311     for(;;) {
00312         if (len < 1)
00313             goto error_redo;
00314         c = avio_r8(s->pb);
00315         len--;
00316         /* XXX: for mpeg1, should test only bit 7 */
00317         if (c != 0xff)
00318             break;
00319     }
00320     if ((c & 0xc0) == 0x40) {
00321         /* buffer scale & size */
00322         avio_r8(s->pb);
00323         c = avio_r8(s->pb);
00324         len -= 2;
00325     }
00326     if ((c & 0xe0) == 0x20) {
00327         dts = pts = get_pts(s->pb, c);
00328         len -= 4;
00329         if (c & 0x10){
00330             dts = get_pts(s->pb, -1);
00331             len -= 5;
00332         }
00333     } else if ((c & 0xc0) == 0x80) {
00334         /* mpeg 2 PES */
00335 #if 0 /* some streams have this field set for no apparent reason */
00336         if ((c & 0x30) != 0) {
00337             /* Encrypted multiplex not handled */
00338             goto redo;
00339         }
00340 #endif
00341         flags = avio_r8(s->pb);
00342         header_len = avio_r8(s->pb);
00343         len -= 2;
00344         if (header_len > len)
00345             goto error_redo;
00346         len -= header_len;
00347         if (flags & 0x80) {
00348             dts = pts = get_pts(s->pb, -1);
00349             header_len -= 5;
00350             if (flags & 0x40) {
00351                 dts = get_pts(s->pb, -1);
00352                 header_len -= 5;
00353             }
00354         }
00355         if (flags & 0x3f && header_len == 0){
00356             flags &= 0xC0;
00357             av_log(s, AV_LOG_WARNING, "Further flags set but no bytes left\n");
00358         }
00359         if (flags & 0x01) { /* PES extension */
00360             pes_ext = avio_r8(s->pb);
00361             header_len--;
00362             /* Skip PES private data, program packet sequence counter and P-STD buffer */
00363             skip = (pes_ext >> 4) & 0xb;
00364             skip += skip & 0x9;
00365             if (pes_ext & 0x40 || skip > header_len){
00366                 av_log(s, AV_LOG_WARNING, "pes_ext %X is invalid\n", pes_ext);
00367                 pes_ext=skip=0;
00368             }
00369             avio_skip(s->pb, skip);
00370             header_len -= skip;
00371 
00372             if (pes_ext & 0x01) { /* PES extension 2 */
00373                 ext2_len = avio_r8(s->pb);
00374                 header_len--;
00375                 if ((ext2_len & 0x7f) > 0) {
00376                     id_ext = avio_r8(s->pb);
00377                     if ((id_ext & 0x80) == 0)
00378                         startcode = ((startcode & 0xff) << 8) | id_ext;
00379                     header_len--;
00380                 }
00381             }
00382         }
00383         if(header_len < 0)
00384             goto error_redo;
00385         avio_skip(s->pb, header_len);
00386     }
00387     else if( c!= 0xf )
00388         goto redo;
00389 
00390     if (startcode == PRIVATE_STREAM_1 && !m->psm_es_type[startcode & 0xff]) {
00391         startcode = avio_r8(s->pb);
00392         len--;
00393         if (startcode >= 0x80 && startcode <= 0xcf) {
00394             /* audio: skip header */
00395             avio_r8(s->pb);
00396             avio_r8(s->pb);
00397             avio_r8(s->pb);
00398             len -= 3;
00399             if (startcode >= 0xb0 && startcode <= 0xbf) {
00400                 /* MLP/TrueHD audio has a 4-byte header */
00401                 avio_r8(s->pb);
00402                 len--;
00403             }
00404         }
00405     }
00406     if(len<0)
00407         goto error_redo;
00408     if(dts != AV_NOPTS_VALUE && ppos){
00409         int i;
00410         for(i=0; i<s->nb_streams; i++){
00411             if(startcode == s->streams[i]->id &&
00412                s->pb->seekable /* index useless on streams anyway */) {
00413                 ff_reduce_index(s, i);
00414                 av_add_index_entry(s->streams[i], *ppos, dts, 0, 0, AVINDEX_KEYFRAME /* FIXME keyframe? */);
00415             }
00416         }
00417     }
00418 
00419     *pstart_code = startcode;
00420     *ppts = pts;
00421     *pdts = dts;
00422     return len;
00423 }
00424 
00425 static int mpegps_read_packet(AVFormatContext *s,
00426                               AVPacket *pkt)
00427 {
00428     MpegDemuxContext *m = s->priv_data;
00429     AVStream *st;
00430     int len, startcode, i, es_type, ret;
00431     int request_probe= 0;
00432     enum CodecID codec_id = CODEC_ID_NONE;
00433     enum AVMediaType type;
00434     int64_t pts, dts, dummy_pos; //dummy_pos is needed for the index building to work
00435     uint8_t av_uninit(dvdaudio_substream_type);
00436 
00437  redo:
00438     len = mpegps_read_pes_header(s, &dummy_pos, &startcode, &pts, &dts);
00439     if (len < 0)
00440         return len;
00441 
00442     if(startcode == 0x1bd) {
00443         dvdaudio_substream_type = avio_r8(s->pb);
00444         avio_skip(s->pb, 3);
00445         len -= 4;
00446     }
00447 
00448     /* now find stream */
00449     for(i=0;i<s->nb_streams;i++) {
00450         st = s->streams[i];
00451         if (st->id == startcode)
00452             goto found;
00453     }
00454 
00455     es_type = m->psm_es_type[startcode & 0xff];
00456     if(es_type > 0 && es_type != STREAM_TYPE_PRIVATE_DATA){
00457         if(es_type == STREAM_TYPE_VIDEO_MPEG1){
00458             codec_id = CODEC_ID_MPEG2VIDEO;
00459             type = AVMEDIA_TYPE_VIDEO;
00460         } else if(es_type == STREAM_TYPE_VIDEO_MPEG2){
00461             codec_id = CODEC_ID_MPEG2VIDEO;
00462             type = AVMEDIA_TYPE_VIDEO;
00463         } else if(es_type == STREAM_TYPE_AUDIO_MPEG1 ||
00464                   es_type == STREAM_TYPE_AUDIO_MPEG2){
00465             codec_id = CODEC_ID_MP3;
00466             type = AVMEDIA_TYPE_AUDIO;
00467         } else if(es_type == STREAM_TYPE_AUDIO_AAC){
00468             codec_id = CODEC_ID_AAC;
00469             type = AVMEDIA_TYPE_AUDIO;
00470         } else if(es_type == STREAM_TYPE_VIDEO_MPEG4){
00471             codec_id = CODEC_ID_MPEG4;
00472             type = AVMEDIA_TYPE_VIDEO;
00473         } else if(es_type == STREAM_TYPE_VIDEO_H264){
00474             codec_id = CODEC_ID_H264;
00475             type = AVMEDIA_TYPE_VIDEO;
00476         } else if(es_type == STREAM_TYPE_AUDIO_AC3){
00477             codec_id = CODEC_ID_AC3;
00478             type = AVMEDIA_TYPE_AUDIO;
00479         } else {
00480             goto skip;
00481         }
00482     } else if (startcode >= 0x1e0 && startcode <= 0x1ef) {
00483         static const unsigned char avs_seqh[4] = { 0, 0, 1, 0xb0 };
00484         unsigned char buf[8];
00485         avio_read(s->pb, buf, 8);
00486         avio_seek(s->pb, -8, SEEK_CUR);
00487         if(!memcmp(buf, avs_seqh, 4) && (buf[6] != 0 || buf[7] != 1))
00488             codec_id = CODEC_ID_CAVS;
00489         else
00490             request_probe= 1;
00491         type = AVMEDIA_TYPE_VIDEO;
00492     } else if (startcode >= 0x1c0 && startcode <= 0x1df) {
00493         type = AVMEDIA_TYPE_AUDIO;
00494         codec_id = m->sofdec > 0 ? CODEC_ID_ADPCM_ADX : CODEC_ID_MP2;
00495     } else if (startcode >= 0x80 && startcode <= 0x87) {
00496         type = AVMEDIA_TYPE_AUDIO;
00497         codec_id = CODEC_ID_AC3;
00498     } else if (  ( startcode >= 0x88 && startcode <= 0x8f)
00499                ||( startcode >= 0x98 && startcode <= 0x9f)) {
00500         /* 0x90 - 0x97 is reserved for SDDS in DVD specs */
00501         type = AVMEDIA_TYPE_AUDIO;
00502         codec_id = CODEC_ID_DTS;
00503     } else if (startcode >= 0xa0 && startcode <= 0xaf) {
00504         type = AVMEDIA_TYPE_AUDIO;
00505         /* 16 bit form will be handled as CODEC_ID_PCM_S16BE */
00506         codec_id = CODEC_ID_PCM_DVD;
00507     } else if (startcode >= 0xb0 && startcode <= 0xbf) {
00508         type = AVMEDIA_TYPE_AUDIO;
00509         codec_id = CODEC_ID_TRUEHD;
00510     } else if (startcode >= 0xc0 && startcode <= 0xcf) {
00511         /* Used for both AC-3 and E-AC-3 in EVOB files */
00512         type = AVMEDIA_TYPE_AUDIO;
00513         codec_id = CODEC_ID_AC3;
00514     } else if (startcode >= 0x20 && startcode <= 0x3f) {
00515         type = AVMEDIA_TYPE_SUBTITLE;
00516         codec_id = CODEC_ID_DVD_SUBTITLE;
00517     } else if (startcode >= 0xfd55 && startcode <= 0xfd5f) {
00518         type = AVMEDIA_TYPE_VIDEO;
00519         codec_id = CODEC_ID_VC1;
00520     } else if (startcode == 0x1bd) {
00521         // check dvd audio substream type
00522         type = AVMEDIA_TYPE_AUDIO;
00523         switch(dvdaudio_substream_type & 0xe0) {
00524         case 0xa0:  codec_id = CODEC_ID_PCM_DVD;
00525                     break;
00526         case 0x80:  if((dvdaudio_substream_type & 0xf8) == 0x88)
00527                          codec_id = CODEC_ID_DTS;
00528                     else codec_id = CODEC_ID_AC3;
00529                     break;
00530         default:    av_log(s, AV_LOG_ERROR, "Unknown 0x1bd sub-stream\n");
00531                     goto skip;
00532         }
00533     } else {
00534     skip:
00535         /* skip packet */
00536         avio_skip(s->pb, len);
00537         goto redo;
00538     }
00539     /* no stream found: add a new stream */
00540     st = avformat_new_stream(s, NULL);
00541     if (!st)
00542         goto skip;
00543     st->id = startcode;
00544     st->codec->codec_type = type;
00545     st->codec->codec_id = codec_id;
00546     st->request_probe     = request_probe;
00547     if (codec_id != CODEC_ID_PCM_S16BE)
00548         st->need_parsing = AVSTREAM_PARSE_FULL;
00549  found:
00550     if(st->discard >= AVDISCARD_ALL)
00551         goto skip;
00552     if ((startcode >= 0xa0 && startcode <= 0xaf) ||
00553         (startcode == 0x1bd && ((dvdaudio_substream_type & 0xe0) == 0xa0))) {
00554         int b1, freq;
00555 
00556         /* for LPCM, we just skip the header and consider it is raw
00557            audio data */
00558         if (len <= 3)
00559             goto skip;
00560         avio_r8(s->pb); /* emphasis (1), muse(1), reserved(1), frame number(5) */
00561         b1 = avio_r8(s->pb); /* quant (2), freq(2), reserved(1), channels(3) */
00562         avio_r8(s->pb); /* dynamic range control (0x80 = off) */
00563         len -= 3;
00564         freq = (b1 >> 4) & 3;
00565         st->codec->sample_rate = lpcm_freq_tab[freq];
00566         st->codec->channels = 1 + (b1 & 7);
00567         st->codec->bits_per_coded_sample = 16 + ((b1 >> 6) & 3) * 4;
00568         st->codec->bit_rate = st->codec->channels *
00569                               st->codec->sample_rate *
00570                               st->codec->bits_per_coded_sample;
00571         if (st->codec->bits_per_coded_sample == 16)
00572             st->codec->codec_id = CODEC_ID_PCM_S16BE;
00573         else if (st->codec->bits_per_coded_sample == 28)
00574             return AVERROR(EINVAL);
00575     }
00576     ret = av_get_packet(s->pb, pkt, len);
00577     pkt->pts = pts;
00578     pkt->dts = dts;
00579     pkt->pos = dummy_pos;
00580     pkt->stream_index = st->index;
00581     av_dlog(s, "%d: pts=%0.3f dts=%0.3f size=%d\n",
00582             pkt->stream_index, pkt->pts / 90000.0, pkt->dts / 90000.0,
00583             pkt->size);
00584 
00585     return (ret < 0) ? ret : 0;
00586 }
00587 
00588 static int64_t mpegps_read_dts(AVFormatContext *s, int stream_index,
00589                                int64_t *ppos, int64_t pos_limit)
00590 {
00591     int len, startcode;
00592     int64_t pos, pts, dts;
00593 
00594     pos = *ppos;
00595     if (avio_seek(s->pb, pos, SEEK_SET) < 0)
00596         return AV_NOPTS_VALUE;
00597 
00598     for(;;) {
00599         len = mpegps_read_pes_header(s, &pos, &startcode, &pts, &dts);
00600         if (len < 0) {
00601             av_dlog(s, "none (ret=%d)\n", len);
00602             return AV_NOPTS_VALUE;
00603         }
00604         if (startcode == s->streams[stream_index]->id &&
00605             dts != AV_NOPTS_VALUE) {
00606             break;
00607         }
00608         avio_skip(s->pb, len);
00609     }
00610     av_dlog(s, "pos=0x%"PRIx64" dts=0x%"PRIx64" %0.3f\n",
00611             pos, dts, dts / 90000.0);
00612     *ppos = pos;
00613     return dts;
00614 }
00615 
00616 AVInputFormat ff_mpegps_demuxer = {
00617     .name           = "mpeg",
00618     .long_name      = NULL_IF_CONFIG_SMALL("MPEG-PS format"),
00619     .priv_data_size = sizeof(MpegDemuxContext),
00620     .read_probe     = mpegps_probe,
00621     .read_header    = mpegps_read_header,
00622     .read_packet    = mpegps_read_packet,
00623     .read_timestamp = mpegps_read_dts,
00624     .flags = AVFMT_SHOW_IDS|AVFMT_TS_DISCONT,
00625 };