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 (audio > 12 || vid > 3 || 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 + 2*invalid) ? 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     //Have\ Yourself\ a\ Merry\ Little\ Christmas.mp3 0 0 0 5 0 1 len:21618
00099     return score;
00100 }
00101 
00102 
00103 typedef struct MpegDemuxContext {
00104     int32_t header_state;
00105     unsigned char psm_es_type[256];
00106     int sofdec;
00107 } MpegDemuxContext;
00108 
00109 static int mpegps_read_header(AVFormatContext *s)
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 
00177 static long mpegps_psm_parse(MpegDemuxContext *m, AVIOContext *pb)
00178 {
00179     int psm_length, ps_info_length, es_map_length;
00180 
00181     psm_length = avio_rb16(pb);
00182     avio_r8(pb);
00183     avio_r8(pb);
00184     ps_info_length = avio_rb16(pb);
00185 
00186     /* skip program_stream_info */
00187     avio_skip(pb, ps_info_length);
00188     es_map_length = avio_rb16(pb);
00189 
00190     /* at least one es available? */
00191     while (es_map_length >= 4){
00192         unsigned char type      = avio_r8(pb);
00193         unsigned char es_id     = avio_r8(pb);
00194         uint16_t es_info_length = avio_rb16(pb);
00195         /* remember mapping from stream id to stream type */
00196         m->psm_es_type[es_id] = type;
00197         /* skip program_stream_info */
00198         avio_skip(pb, es_info_length);
00199         es_map_length -= 4 + es_info_length;
00200     }
00201     avio_rb32(pb); /* crc32 */
00202     return 2 + psm_length;
00203 }
00204 
00205 /* read the next PES header. Return its position in ppos
00206    (if not NULL), and its start code, pts and dts.
00207  */
00208 static int mpegps_read_pes_header(AVFormatContext *s,
00209                                   int64_t *ppos, int *pstart_code,
00210                                   int64_t *ppts, int64_t *pdts)
00211 {
00212     MpegDemuxContext *m = s->priv_data;
00213     int len, size, startcode, c, flags, header_len;
00214     int pes_ext, ext2_len, id_ext, skip;
00215     int64_t pts, dts;
00216     int64_t last_sync= avio_tell(s->pb);
00217 
00218  error_redo:
00219         avio_seek(s->pb, last_sync, SEEK_SET);
00220  redo:
00221         /* next start code (should be immediately after) */
00222         m->header_state = 0xff;
00223         size = MAX_SYNC_SIZE;
00224         startcode = find_next_start_code(s->pb, &size, &m->header_state);
00225         last_sync = avio_tell(s->pb);
00226     //printf("startcode=%x pos=0x%"PRIx64"\n", startcode, avio_tell(s->pb));
00227     if (startcode < 0){
00228         if(url_feof(s->pb))
00229             return AVERROR_EOF;
00230         //FIXME we should remember header_state
00231         return AVERROR(EAGAIN);
00232     }
00233 
00234     if (startcode == PACK_START_CODE)
00235         goto redo;
00236     if (startcode == SYSTEM_HEADER_START_CODE)
00237         goto redo;
00238     if (startcode == PADDING_STREAM) {
00239         avio_skip(s->pb, avio_rb16(s->pb));
00240         goto redo;
00241     }
00242     if (startcode == PRIVATE_STREAM_2) {
00243         len = avio_rb16(s->pb);
00244         if (!m->sofdec) {
00245             while (len-- >= 6) {
00246                 if (avio_r8(s->pb) == 'S') {
00247                     uint8_t buf[5];
00248                     avio_read(s->pb, buf, sizeof(buf));
00249                     m->sofdec = !memcmp(buf, "ofdec", 5);
00250                     len -= sizeof(buf);
00251                     break;
00252                 }
00253             }
00254             m->sofdec -= !m->sofdec;
00255         }
00256         avio_skip(s->pb, len);
00257         goto redo;
00258     }
00259     if (startcode == PROGRAM_STREAM_MAP) {
00260         mpegps_psm_parse(m, s->pb);
00261         goto redo;
00262     }
00263 
00264     /* find matching stream */
00265     if (!((startcode >= 0x1c0 && startcode <= 0x1df) ||
00266           (startcode >= 0x1e0 && startcode <= 0x1ef) ||
00267           (startcode == 0x1bd) || (startcode == 0x1fd)))
00268         goto redo;
00269     if (ppos) {
00270         *ppos = avio_tell(s->pb) - 4;
00271     }
00272     len = avio_rb16(s->pb);
00273     pts =
00274     dts = AV_NOPTS_VALUE;
00275     /* stuffing */
00276     for(;;) {
00277         if (len < 1)
00278             goto error_redo;
00279         c = avio_r8(s->pb);
00280         len--;
00281         /* XXX: for mpeg1, should test only bit 7 */
00282         if (c != 0xff)
00283             break;
00284     }
00285     if ((c & 0xc0) == 0x40) {
00286         /* buffer scale & size */
00287         avio_r8(s->pb);
00288         c = avio_r8(s->pb);
00289         len -= 2;
00290     }
00291     if ((c & 0xe0) == 0x20) {
00292         dts = pts = get_pts(s->pb, c);
00293         len -= 4;
00294         if (c & 0x10){
00295             dts = get_pts(s->pb, -1);
00296             len -= 5;
00297         }
00298     } else if ((c & 0xc0) == 0x80) {
00299         /* mpeg 2 PES */
00300         flags = avio_r8(s->pb);
00301         header_len = avio_r8(s->pb);
00302         len -= 2;
00303         if (header_len > len)
00304             goto error_redo;
00305         len -= header_len;
00306         if (flags & 0x80) {
00307             dts = pts = get_pts(s->pb, -1);
00308             header_len -= 5;
00309             if (flags & 0x40) {
00310                 dts = get_pts(s->pb, -1);
00311                 header_len -= 5;
00312             }
00313         }
00314         if (flags & 0x3f && header_len == 0){
00315             flags &= 0xC0;
00316             av_log(s, AV_LOG_WARNING, "Further flags set but no bytes left\n");
00317         }
00318         if (flags & 0x01) { /* PES extension */
00319             pes_ext = avio_r8(s->pb);
00320             header_len--;
00321             /* Skip PES private data, program packet sequence counter and P-STD buffer */
00322             skip = (pes_ext >> 4) & 0xb;
00323             skip += skip & 0x9;
00324             if (pes_ext & 0x40 || skip > header_len){
00325                 av_log(s, AV_LOG_WARNING, "pes_ext %X is invalid\n", pes_ext);
00326                 pes_ext=skip=0;
00327             }
00328             avio_skip(s->pb, skip);
00329             header_len -= skip;
00330 
00331             if (pes_ext & 0x01) { /* PES extension 2 */
00332                 ext2_len = avio_r8(s->pb);
00333                 header_len--;
00334                 if ((ext2_len & 0x7f) > 0) {
00335                     id_ext = avio_r8(s->pb);
00336                     if ((id_ext & 0x80) == 0)
00337                         startcode = ((startcode & 0xff) << 8) | id_ext;
00338                     header_len--;
00339                 }
00340             }
00341         }
00342         if(header_len < 0)
00343             goto error_redo;
00344         avio_skip(s->pb, header_len);
00345     }
00346     else if( c!= 0xf )
00347         goto redo;
00348 
00349     if (startcode == PRIVATE_STREAM_1) {
00350         startcode = avio_r8(s->pb);
00351         len--;
00352     }
00353     if(len<0)
00354         goto error_redo;
00355     if(dts != AV_NOPTS_VALUE && ppos){
00356         int i;
00357         for(i=0; i<s->nb_streams; i++){
00358             if(startcode == s->streams[i]->id &&
00359                s->pb->seekable /* index useless on streams anyway */) {
00360                 ff_reduce_index(s, i);
00361                 av_add_index_entry(s->streams[i], *ppos, dts, 0, 0, AVINDEX_KEYFRAME /* FIXME keyframe? */);
00362             }
00363         }
00364     }
00365 
00366     *pstart_code = startcode;
00367     *ppts = pts;
00368     *pdts = dts;
00369     return len;
00370 }
00371 
00372 static int mpegps_read_packet(AVFormatContext *s,
00373                               AVPacket *pkt)
00374 {
00375     MpegDemuxContext *m = s->priv_data;
00376     AVStream *st;
00377     int len, startcode, i, es_type, ret;
00378     int lpcm_header_len;
00379     int request_probe= 0;
00380     enum AVCodecID codec_id = AV_CODEC_ID_NONE;
00381     enum AVMediaType type;
00382     int64_t pts, dts, dummy_pos; //dummy_pos is needed for the index building to work
00383 
00384  redo:
00385     len = mpegps_read_pes_header(s, &dummy_pos, &startcode, &pts, &dts);
00386     if (len < 0)
00387         return len;
00388 
00389     if (startcode >= 0x80 && startcode <= 0xcf) {
00390         if(len < 4)
00391             goto skip;
00392 
00393         /* audio: skip header */
00394         avio_r8(s->pb);
00395         lpcm_header_len = avio_rb16(s->pb);
00396         len -= 3;
00397         if (startcode >= 0xb0 && startcode <= 0xbf) {
00398             /* MLP/TrueHD audio has a 4-byte header */
00399             avio_r8(s->pb);
00400             len--;
00401         }
00402     }
00403 
00404     /* now find stream */
00405     for(i=0;i<s->nb_streams;i++) {
00406         st = s->streams[i];
00407         if (st->id == startcode)
00408             goto found;
00409     }
00410 
00411     es_type = m->psm_es_type[startcode & 0xff];
00412     if(es_type > 0 && es_type != STREAM_TYPE_PRIVATE_DATA){
00413         if(es_type == STREAM_TYPE_VIDEO_MPEG1){
00414             codec_id = AV_CODEC_ID_MPEG2VIDEO;
00415             type = AVMEDIA_TYPE_VIDEO;
00416         } else if(es_type == STREAM_TYPE_VIDEO_MPEG2){
00417             codec_id = AV_CODEC_ID_MPEG2VIDEO;
00418             type = AVMEDIA_TYPE_VIDEO;
00419         } else if(es_type == STREAM_TYPE_AUDIO_MPEG1 ||
00420                   es_type == STREAM_TYPE_AUDIO_MPEG2){
00421             codec_id = AV_CODEC_ID_MP3;
00422             type = AVMEDIA_TYPE_AUDIO;
00423         } else if(es_type == STREAM_TYPE_AUDIO_AAC){
00424             codec_id = AV_CODEC_ID_AAC;
00425             type = AVMEDIA_TYPE_AUDIO;
00426         } else if(es_type == STREAM_TYPE_VIDEO_MPEG4){
00427             codec_id = AV_CODEC_ID_MPEG4;
00428             type = AVMEDIA_TYPE_VIDEO;
00429         } else if(es_type == STREAM_TYPE_VIDEO_H264){
00430             codec_id = AV_CODEC_ID_H264;
00431             type = AVMEDIA_TYPE_VIDEO;
00432         } else if(es_type == STREAM_TYPE_AUDIO_AC3){
00433             codec_id = AV_CODEC_ID_AC3;
00434             type = AVMEDIA_TYPE_AUDIO;
00435         } else {
00436             goto skip;
00437         }
00438     } else if (startcode >= 0x1e0 && startcode <= 0x1ef) {
00439         static const unsigned char avs_seqh[4] = { 0, 0, 1, 0xb0 };
00440         unsigned char buf[8];
00441         avio_read(s->pb, buf, 8);
00442         avio_seek(s->pb, -8, SEEK_CUR);
00443         if(!memcmp(buf, avs_seqh, 4) && (buf[6] != 0 || buf[7] != 1))
00444             codec_id = AV_CODEC_ID_CAVS;
00445         else
00446             request_probe= 1;
00447         type = AVMEDIA_TYPE_VIDEO;
00448     } else if (startcode >= 0x1c0 && startcode <= 0x1df) {
00449         type = AVMEDIA_TYPE_AUDIO;
00450         codec_id = m->sofdec > 0 ? AV_CODEC_ID_ADPCM_ADX : AV_CODEC_ID_MP2;
00451     } else if (startcode >= 0x80 && startcode <= 0x87) {
00452         type = AVMEDIA_TYPE_AUDIO;
00453         codec_id = AV_CODEC_ID_AC3;
00454     } else if (  ( startcode >= 0x88 && startcode <= 0x8f)
00455                ||( startcode >= 0x98 && startcode <= 0x9f)) {
00456         /* 0x90 - 0x97 is reserved for SDDS in DVD specs */
00457         type = AVMEDIA_TYPE_AUDIO;
00458         codec_id = AV_CODEC_ID_DTS;
00459     } else if (startcode >= 0xa0 && startcode <= 0xaf) {
00460         type = AVMEDIA_TYPE_AUDIO;
00461         if(lpcm_header_len == 6) {
00462             codec_id = AV_CODEC_ID_MLP;
00463         } else {
00464             /* 16 bit form will be handled as AV_CODEC_ID_PCM_S16BE */
00465             codec_id = AV_CODEC_ID_PCM_DVD;
00466         }
00467     } else if (startcode >= 0xb0 && startcode <= 0xbf) {
00468         type = AVMEDIA_TYPE_AUDIO;
00469         codec_id = AV_CODEC_ID_TRUEHD;
00470     } else if (startcode >= 0xc0 && startcode <= 0xcf) {
00471         /* Used for both AC-3 and E-AC-3 in EVOB files */
00472         type = AVMEDIA_TYPE_AUDIO;
00473         codec_id = AV_CODEC_ID_AC3;
00474     } else if (startcode >= 0x20 && startcode <= 0x3f) {
00475         type = AVMEDIA_TYPE_SUBTITLE;
00476         codec_id = AV_CODEC_ID_DVD_SUBTITLE;
00477     } else if (startcode >= 0xfd55 && startcode <= 0xfd5f) {
00478         type = AVMEDIA_TYPE_VIDEO;
00479         codec_id = AV_CODEC_ID_VC1;
00480     } else {
00481     skip:
00482         /* skip packet */
00483         avio_skip(s->pb, len);
00484         goto redo;
00485     }
00486     /* no stream found: add a new stream */
00487     st = avformat_new_stream(s, NULL);
00488     if (!st)
00489         goto skip;
00490     st->id = startcode;
00491     st->codec->codec_type = type;
00492     st->codec->codec_id = codec_id;
00493     st->request_probe     = request_probe;
00494     if (codec_id != AV_CODEC_ID_PCM_S16BE)
00495         st->need_parsing = AVSTREAM_PARSE_FULL;
00496  found:
00497     if(st->discard >= AVDISCARD_ALL)
00498         goto skip;
00499     if (startcode >= 0xa0 && startcode <= 0xaf) {
00500       if (lpcm_header_len == 6) {
00501             if (len < 6)
00502                 goto skip;
00503             avio_skip(s->pb, 6);
00504             len -=6;
00505       } else {
00506         int b1, freq;
00507 
00508         /* for LPCM, we just skip the header and consider it is raw
00509            audio data */
00510         if (len <= 3)
00511             goto skip;
00512         avio_r8(s->pb); /* emphasis (1), muse(1), reserved(1), frame number(5) */
00513         b1 = avio_r8(s->pb); /* quant (2), freq(2), reserved(1), channels(3) */
00514         avio_r8(s->pb); /* dynamic range control (0x80 = off) */
00515         len -= 3;
00516         freq = (b1 >> 4) & 3;
00517         st->codec->sample_rate = lpcm_freq_tab[freq];
00518         st->codec->channels = 1 + (b1 & 7);
00519         st->codec->bits_per_coded_sample = 16 + ((b1 >> 6) & 3) * 4;
00520         st->codec->bit_rate = st->codec->channels *
00521                               st->codec->sample_rate *
00522                               st->codec->bits_per_coded_sample;
00523         if (st->codec->bits_per_coded_sample == 16)
00524             st->codec->codec_id = AV_CODEC_ID_PCM_S16BE;
00525         else if (st->codec->bits_per_coded_sample == 28)
00526             return AVERROR(EINVAL);
00527       }
00528     }
00529     ret = av_get_packet(s->pb, pkt, len);
00530     pkt->pts = pts;
00531     pkt->dts = dts;
00532     pkt->pos = dummy_pos;
00533     pkt->stream_index = st->index;
00534     av_dlog(s, "%d: pts=%0.3f dts=%0.3f size=%d\n",
00535             pkt->stream_index, pkt->pts / 90000.0, pkt->dts / 90000.0,
00536             pkt->size);
00537 
00538     return (ret < 0) ? ret : 0;
00539 }
00540 
00541 static int64_t mpegps_read_dts(AVFormatContext *s, int stream_index,
00542                                int64_t *ppos, int64_t pos_limit)
00543 {
00544     int len, startcode;
00545     int64_t pos, pts, dts;
00546 
00547     pos = *ppos;
00548     if (avio_seek(s->pb, pos, SEEK_SET) < 0)
00549         return AV_NOPTS_VALUE;
00550 
00551     for(;;) {
00552         len = mpegps_read_pes_header(s, &pos, &startcode, &pts, &dts);
00553         if (len < 0) {
00554             av_dlog(s, "none (ret=%d)\n", len);
00555             return AV_NOPTS_VALUE;
00556         }
00557         if (startcode == s->streams[stream_index]->id &&
00558             dts != AV_NOPTS_VALUE) {
00559             break;
00560         }
00561         avio_skip(s->pb, len);
00562     }
00563     av_dlog(s, "pos=0x%"PRIx64" dts=0x%"PRIx64" %0.3f\n",
00564             pos, dts, dts / 90000.0);
00565     *ppos = pos;
00566     return dts;
00567 }
00568 
00569 AVInputFormat ff_mpegps_demuxer = {
00570     .name           = "mpeg",
00571     .long_name      = NULL_IF_CONFIG_SMALL("MPEG-PS (MPEG-2 Program Stream)"),
00572     .priv_data_size = sizeof(MpegDemuxContext),
00573     .read_probe     = mpegps_probe,
00574     .read_header    = mpegps_read_header,
00575     .read_packet    = mpegps_read_packet,
00576     .read_timestamp = mpegps_read_dts,
00577     .flags          = AVFMT_SHOW_IDS | AVFMT_TS_DISCONT,
00578 };