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ffmpeg / libavformat / mpeg.c @ 49bd8e4b

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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 len= p->buf[i+1] << 8 | p->buf[i+2];
64
            int pes= check_pes(p->buf+i, p->buf+p->buf_size);
65

    
66
            if(code == SYSTEM_HEADER_START_CODE) sys++;
67
            else if(code == PACK_START_CODE)     pspack++;
68
            else if((code & 0xf0) == VIDEO_ID &&  pes) vid++;
69
            // skip pes payload to avoid start code emulation for private
70
            // and audio streams
71
            else if((code & 0xe0) == AUDIO_ID &&  pes) {audio++; i+=len;}
72
            else if(code == PRIVATE_STREAM_1  &&  pes) {priv1++; i+=len;}
73

    
74
            else if((code & 0xf0) == VIDEO_ID && !pes) invalid++;
75
            else if((code & 0xe0) == AUDIO_ID && !pes) invalid++;
76
            else if(code == PRIVATE_STREAM_1  && !pes) invalid++;
77
        }
78
    }
79

    
80
    if(vid+audio > invalid)     /* invalid VDR files nd short PES streams */
81
        score= AVPROBE_SCORE_MAX/4;
82

    
83
//av_log(NULL, AV_LOG_ERROR, "%d %d %d %d %d %d len:%d\n", sys, priv1, pspack,vid, audio, invalid, p->buf_size);
84
    if(sys>invalid && sys*9 <= pspack*10)
85
        return pspack > 2 ? AVPROBE_SCORE_MAX/2+2 : AVPROBE_SCORE_MAX/4; // +1 for .mpg
86
    if(pspack > invalid && (priv1+vid+audio)*10 >= pspack*9)
87
        return pspack > 2 ? AVPROBE_SCORE_MAX/2+2 : AVPROBE_SCORE_MAX/4; // +1 for .mpg
88
    if((!!vid ^ !!audio) && (audio > 4 || vid > 1) && !sys && !pspack && p->buf_size>2048 && vid + audio > invalid) /* PES stream */
89
        return (audio > 12 || vid > 3) ? AVPROBE_SCORE_MAX/2+2 : AVPROBE_SCORE_MAX/4;
90

    
91
    //02-Penguin.flac has sys:0 priv1:0 pspack:0 vid:0 audio:1
92
    //mp3_misidentified_2.mp3 has sys:0 priv1:0 pspack:0 vid:0 audio:6
93
    return score;
94
}
95

    
96

    
97
typedef struct MpegDemuxContext {
98
    int32_t header_state;
99
    unsigned char psm_es_type[256];
100
    int sofdec;
101
} MpegDemuxContext;
102

    
103
static int mpegps_read_header(AVFormatContext *s,
104
                              AVFormatParameters *ap)
105
{
106
    MpegDemuxContext *m = s->priv_data;
107
    const char *sofdec = "Sofdec";
108
    int v, i = 0;
109

    
110
    m->header_state = 0xff;
111
    s->ctx_flags |= AVFMTCTX_NOHEADER;
112

    
113
    m->sofdec = -1;
114
    do {
115
        v = get_byte(s->pb);
116
        m->header_state = m->header_state << 8 | v;
117
        m->sofdec++;
118
    } while (v == sofdec[i] && i++ < 6);
119

    
120
    m->sofdec = (m->sofdec == 6) ? 1 : 0;
121

    
122
    /* no need to do more */
123
    return 0;
124
}
125

    
126
static int64_t get_pts(ByteIOContext *pb, int c)
127
{
128
    uint8_t buf[5];
129

    
130
    buf[0] = c<0 ? get_byte(pb) : c;
131
    get_buffer(pb, buf+1, 4);
132

    
133
    return ff_parse_pes_pts(buf);
134
}
135

    
136
static int find_next_start_code(ByteIOContext *pb, int *size_ptr,
137
                                int32_t *header_state)
138
{
139
    unsigned int state, v;
140
    int val, n;
141

    
142
    state = *header_state;
143
    n = *size_ptr;
144
    while (n > 0) {
145
        if (url_feof(pb))
146
            break;
147
        v = get_byte(pb);
148
        n--;
149
        if (state == 0x000001) {
150
            state = ((state << 8) | v) & 0xffffff;
151
            val = state;
152
            goto found;
153
        }
154
        state = ((state << 8) | v) & 0xffffff;
155
    }
156
    val = -1;
157
 found:
158
    *header_state = state;
159
    *size_ptr = n;
160
    return val;
161
}
162

    
163
#if 0 /* unused, remove? */
164
/* XXX: optimize */
165
static int find_prev_start_code(ByteIOContext *pb, int *size_ptr)
166
{
167
    int64_t pos, pos_start;
168
    int max_size, start_code;
169

170
    max_size = *size_ptr;
171
    pos_start = url_ftell(pb);
172

173
    /* in order to go faster, we fill the buffer */
174
    pos = pos_start - 16386;
175
    if (pos < 0)
176
        pos = 0;
177
    url_fseek(pb, pos, SEEK_SET);
178
    get_byte(pb);
179

180
    pos = pos_start;
181
    for(;;) {
182
        pos--;
183
        if (pos < 0 || (pos_start - pos) >= max_size) {
184
            start_code = -1;
185
            goto the_end;
186
        }
187
        url_fseek(pb, pos, SEEK_SET);
188
        start_code = get_be32(pb);
189
        if ((start_code & 0xffffff00) == 0x100)
190
            break;
191
    }
192
 the_end:
193
    *size_ptr = pos_start - pos;
194
    return start_code;
195
}
196
#endif
197

    
198
/**
199
 * Extract stream types from a program stream map
200
 * According to ISO/IEC 13818-1 ('MPEG-2 Systems') table 2-35
201
 *
202
 * @return number of bytes occupied by PSM in the bitstream
203
 */
204
static long mpegps_psm_parse(MpegDemuxContext *m, ByteIOContext *pb)
205
{
206
    int psm_length, ps_info_length, es_map_length;
207

    
208
    psm_length = get_be16(pb);
209
    get_byte(pb);
210
    get_byte(pb);
211
    ps_info_length = get_be16(pb);
212

    
213
    /* skip program_stream_info */
214
    url_fskip(pb, ps_info_length);
215
    es_map_length = get_be16(pb);
216

    
217
    /* at least one es available? */
218
    while (es_map_length >= 4){
219
        unsigned char type      = get_byte(pb);
220
        unsigned char es_id     = get_byte(pb);
221
        uint16_t es_info_length = get_be16(pb);
222
        /* remember mapping from stream id to stream type */
223
        m->psm_es_type[es_id] = type;
224
        /* skip program_stream_info */
225
        url_fskip(pb, es_info_length);
226
        es_map_length -= 4 + es_info_length;
227
    }
228
    get_be32(pb); /* crc32 */
229
    return 2 + psm_length;
230
}
231

    
232
/* read the next PES header. Return its position in ppos
233
   (if not NULL), and its start code, pts and dts.
234
 */
235
static int mpegps_read_pes_header(AVFormatContext *s,
236
                                  int64_t *ppos, int *pstart_code,
237
                                  int64_t *ppts, int64_t *pdts)
238
{
239
    MpegDemuxContext *m = s->priv_data;
240
    int len, size, startcode, c, flags, header_len;
241
    int pes_ext, ext2_len, id_ext, skip;
242
    int64_t pts, dts;
243
    int64_t last_sync= url_ftell(s->pb);
244

    
245
 error_redo:
246
        url_fseek(s->pb, last_sync, SEEK_SET);
247
 redo:
248
        /* next start code (should be immediately after) */
249
        m->header_state = 0xff;
250
        size = MAX_SYNC_SIZE;
251
        startcode = find_next_start_code(s->pb, &size, &m->header_state);
252
        last_sync = url_ftell(s->pb);
253
    //printf("startcode=%x pos=0x%"PRIx64"\n", startcode, url_ftell(s->pb));
254
    if (startcode < 0){
255
        if(url_feof(s->pb))
256
            return AVERROR_EOF;
257
        //FIXME we should remember header_state
258
        return AVERROR(EAGAIN);
259
    }
260

    
261
    if (startcode == PACK_START_CODE)
262
        goto redo;
263
    if (startcode == SYSTEM_HEADER_START_CODE)
264
        goto redo;
265
    if (startcode == PADDING_STREAM) {
266
        url_fskip(s->pb, get_be16(s->pb));
267
        goto redo;
268
    }
269
    if (startcode == PRIVATE_STREAM_2) {
270
        len = get_be16(s->pb);
271
        if (!m->sofdec) {
272
            while (len-- >= 6) {
273
                if (get_byte(s->pb) == 'S') {
274
                    uint8_t buf[5];
275
                    get_buffer(s->pb, buf, sizeof(buf));
276
                    m->sofdec = !memcmp(buf, "ofdec", 5);
277
                    len -= sizeof(buf);
278
                    break;
279
                }
280
            }
281
            m->sofdec -= !m->sofdec;
282
        }
283
        url_fskip(s->pb, len);
284
        goto redo;
285
    }
286
    if (startcode == PROGRAM_STREAM_MAP) {
287
        mpegps_psm_parse(m, s->pb);
288
        goto redo;
289
    }
290

    
291
    /* find matching stream */
292
    if (!((startcode >= 0x1c0 && startcode <= 0x1df) ||
293
          (startcode >= 0x1e0 && startcode <= 0x1ef) ||
294
          (startcode == 0x1bd) || (startcode == 0x1fd)))
295
        goto redo;
296
    if (ppos) {
297
        *ppos = url_ftell(s->pb) - 4;
298
    }
299
    len = get_be16(s->pb);
300
    pts =
301
    dts = AV_NOPTS_VALUE;
302
    /* stuffing */
303
    for(;;) {
304
        if (len < 1)
305
            goto error_redo;
306
        c = get_byte(s->pb);
307
        len--;
308
        /* XXX: for mpeg1, should test only bit 7 */
309
        if (c != 0xff)
310
            break;
311
    }
312
    if ((c & 0xc0) == 0x40) {
313
        /* buffer scale & size */
314
        get_byte(s->pb);
315
        c = get_byte(s->pb);
316
        len -= 2;
317
    }
318
    if ((c & 0xe0) == 0x20) {
319
        dts = pts = get_pts(s->pb, c);
320
        len -= 4;
321
        if (c & 0x10){
322
            dts = get_pts(s->pb, -1);
323
            len -= 5;
324
        }
325
    } else if ((c & 0xc0) == 0x80) {
326
        /* mpeg 2 PES */
327
#if 0 /* some streams have this field set for no apparent reason */
328
        if ((c & 0x30) != 0) {
329
            /* Encrypted multiplex not handled */
330
            goto redo;
331
        }
332
#endif
333
        flags = get_byte(s->pb);
334
        header_len = get_byte(s->pb);
335
        len -= 2;
336
        if (header_len > len)
337
            goto error_redo;
338
        len -= header_len;
339
        if (flags & 0x80) {
340
            dts = pts = get_pts(s->pb, -1);
341
            header_len -= 5;
342
            if (flags & 0x40) {
343
                dts = get_pts(s->pb, -1);
344
                header_len -= 5;
345
            }
346
        }
347
        if (flags & 0x3f && header_len == 0){
348
            flags &= 0xC0;
349
            av_log(s, AV_LOG_WARNING, "Further flags set but no bytes left\n");
350
        }
351
        if (flags & 0x01) { /* PES extension */
352
            pes_ext = get_byte(s->pb);
353
            header_len--;
354
            /* Skip PES private data, program packet sequence counter and P-STD buffer */
355
            skip = (pes_ext >> 4) & 0xb;
356
            skip += skip & 0x9;
357
            if (pes_ext & 0x40 || skip > header_len){
358
                av_log(s, AV_LOG_WARNING, "pes_ext %X is invalid\n", pes_ext);
359
                pes_ext=skip=0;
360
            }
361
            url_fskip(s->pb, skip);
362
            header_len -= skip;
363

    
364
            if (pes_ext & 0x01) { /* PES extension 2 */
365
                ext2_len = get_byte(s->pb);
366
                header_len--;
367
                if ((ext2_len & 0x7f) > 0) {
368
                    id_ext = get_byte(s->pb);
369
                    if ((id_ext & 0x80) == 0)
370
                        startcode = ((startcode & 0xff) << 8) | id_ext;
371
                    header_len--;
372
                }
373
            }
374
        }
375
        if(header_len < 0)
376
            goto error_redo;
377
        url_fskip(s->pb, header_len);
378
    }
379
    else if( c!= 0xf )
380
        goto redo;
381

    
382
    if (startcode == PRIVATE_STREAM_1 && !m->psm_es_type[startcode & 0xff]) {
383
        startcode = get_byte(s->pb);
384
        len--;
385
        if (startcode >= 0x80 && startcode <= 0xcf) {
386
            /* audio: skip header */
387
            get_byte(s->pb);
388
            get_byte(s->pb);
389
            get_byte(s->pb);
390
            len -= 3;
391
            if (startcode >= 0xb0 && startcode <= 0xbf) {
392
                /* MLP/TrueHD audio has a 4-byte header */
393
                get_byte(s->pb);
394
                len--;
395
            }
396
        }
397
    }
398
    if(len<0)
399
        goto error_redo;
400
    if(dts != AV_NOPTS_VALUE && ppos){
401
        int i;
402
        for(i=0; i<s->nb_streams; i++){
403
            if(startcode == s->streams[i]->id &&
404
               !url_is_streamed(s->pb) /* index useless on streams anyway */) {
405
                ff_reduce_index(s, i);
406
                av_add_index_entry(s->streams[i], *ppos, dts, 0, 0, AVINDEX_KEYFRAME /* FIXME keyframe? */);
407
            }
408
        }
409
    }
410

    
411
    *pstart_code = startcode;
412
    *ppts = pts;
413
    *pdts = dts;
414
    return len;
415
}
416

    
417
static int mpegps_read_packet(AVFormatContext *s,
418
                              AVPacket *pkt)
419
{
420
    MpegDemuxContext *m = s->priv_data;
421
    AVStream *st;
422
    int len, startcode, i, es_type;
423
    enum CodecID codec_id = CODEC_ID_NONE;
424
    enum AVMediaType type;
425
    int64_t pts, dts, dummy_pos; //dummy_pos is needed for the index building to work
426
    uint8_t av_uninit(dvdaudio_substream_type);
427

    
428
 redo:
429
    len = mpegps_read_pes_header(s, &dummy_pos, &startcode, &pts, &dts);
430
    if (len < 0)
431
        return len;
432

    
433
    if(startcode == 0x1bd) {
434
        dvdaudio_substream_type = get_byte(s->pb);
435
        url_fskip(s->pb, 3);
436
        len -= 4;
437
    }
438

    
439
    /* now find stream */
440
    for(i=0;i<s->nb_streams;i++) {
441
        st = s->streams[i];
442
        if (st->id == startcode)
443
            goto found;
444
    }
445

    
446
    es_type = m->psm_es_type[startcode & 0xff];
447
    if(es_type > 0 && es_type != STREAM_TYPE_PRIVATE_DATA){
448
        if(es_type == STREAM_TYPE_VIDEO_MPEG1){
449
            codec_id = CODEC_ID_MPEG2VIDEO;
450
            type = AVMEDIA_TYPE_VIDEO;
451
        } else if(es_type == STREAM_TYPE_VIDEO_MPEG2){
452
            codec_id = CODEC_ID_MPEG2VIDEO;
453
            type = AVMEDIA_TYPE_VIDEO;
454
        } else if(es_type == STREAM_TYPE_AUDIO_MPEG1 ||
455
                  es_type == STREAM_TYPE_AUDIO_MPEG2){
456
            codec_id = CODEC_ID_MP3;
457
            type = AVMEDIA_TYPE_AUDIO;
458
        } else if(es_type == STREAM_TYPE_AUDIO_AAC){
459
            codec_id = CODEC_ID_AAC;
460
            type = AVMEDIA_TYPE_AUDIO;
461
        } else if(es_type == STREAM_TYPE_VIDEO_MPEG4){
462
            codec_id = CODEC_ID_MPEG4;
463
            type = AVMEDIA_TYPE_VIDEO;
464
        } else if(es_type == STREAM_TYPE_VIDEO_H264){
465
            codec_id = CODEC_ID_H264;
466
            type = AVMEDIA_TYPE_VIDEO;
467
        } else if(es_type == STREAM_TYPE_AUDIO_AC3){
468
            codec_id = CODEC_ID_AC3;
469
            type = AVMEDIA_TYPE_AUDIO;
470
        } else {
471
            goto skip;
472
        }
473
    } else if (startcode >= 0x1e0 && startcode <= 0x1ef) {
474
        static const unsigned char avs_seqh[4] = { 0, 0, 1, 0xb0 };
475
        unsigned char buf[8];
476
        get_buffer(s->pb, buf, 8);
477
        url_fseek(s->pb, -8, SEEK_CUR);
478
        if(!memcmp(buf, avs_seqh, 4) && (buf[6] != 0 || buf[7] != 1))
479
            codec_id = CODEC_ID_CAVS;
480
        else
481
            codec_id = CODEC_ID_PROBE;
482
        type = AVMEDIA_TYPE_VIDEO;
483
    } else if (startcode >= 0x1c0 && startcode <= 0x1df) {
484
        type = AVMEDIA_TYPE_AUDIO;
485
        codec_id = m->sofdec > 0 ? CODEC_ID_ADPCM_ADX : CODEC_ID_MP2;
486
    } else if (startcode >= 0x80 && startcode <= 0x87) {
487
        type = AVMEDIA_TYPE_AUDIO;
488
        codec_id = CODEC_ID_AC3;
489
    } else if (  ( startcode >= 0x88 && startcode <= 0x8f)
490
               ||( startcode >= 0x98 && startcode <= 0x9f)) {
491
        /* 0x90 - 0x97 is reserved for SDDS in DVD specs */
492
        type = AVMEDIA_TYPE_AUDIO;
493
        codec_id = CODEC_ID_DTS;
494
    } else if (startcode >= 0xa0 && startcode <= 0xaf) {
495
        type = AVMEDIA_TYPE_AUDIO;
496
        /* 16 bit form will be handled as CODEC_ID_PCM_S16BE */
497
        codec_id = CODEC_ID_PCM_DVD;
498
    } else if (startcode >= 0xb0 && startcode <= 0xbf) {
499
        type = AVMEDIA_TYPE_AUDIO;
500
        codec_id = CODEC_ID_TRUEHD;
501
    } else if (startcode >= 0xc0 && startcode <= 0xcf) {
502
        /* Used for both AC-3 and E-AC-3 in EVOB files */
503
        type = AVMEDIA_TYPE_AUDIO;
504
        codec_id = CODEC_ID_AC3;
505
    } else if (startcode >= 0x20 && startcode <= 0x3f) {
506
        type = AVMEDIA_TYPE_SUBTITLE;
507
        codec_id = CODEC_ID_DVD_SUBTITLE;
508
    } else if (startcode >= 0xfd55 && startcode <= 0xfd5f) {
509
        type = AVMEDIA_TYPE_VIDEO;
510
        codec_id = CODEC_ID_VC1;
511
    } else if (startcode == 0x1bd) {
512
        // check dvd audio substream type
513
        type = AVMEDIA_TYPE_AUDIO;
514
        switch(dvdaudio_substream_type & 0xe0) {
515
        case 0xa0:  codec_id = CODEC_ID_PCM_DVD;
516
                    break;
517
        case 0x80:  if((dvdaudio_substream_type & 0xf8) == 0x88)
518
                         codec_id = CODEC_ID_DTS;
519
                    else codec_id = CODEC_ID_AC3;
520
                    break;
521
        default:    av_log(s, AV_LOG_ERROR, "Unknown 0x1bd sub-stream\n");
522
                    goto skip;
523
        }
524
    } else {
525
    skip:
526
        /* skip packet */
527
        url_fskip(s->pb, len);
528
        goto redo;
529
    }
530
    /* no stream found: add a new stream */
531
    st = av_new_stream(s, startcode);
532
    if (!st)
533
        goto skip;
534
    st->codec->codec_type = type;
535
    st->codec->codec_id = codec_id;
536
    if (codec_id != CODEC_ID_PCM_S16BE)
537
        st->need_parsing = AVSTREAM_PARSE_FULL;
538
 found:
539
    if(st->discard >= AVDISCARD_ALL)
540
        goto skip;
541
    if ((startcode >= 0xa0 && startcode <= 0xaf) ||
542
        (startcode == 0x1bd && ((dvdaudio_substream_type & 0xe0) == 0xa0))) {
543
        int b1, freq;
544

    
545
        /* for LPCM, we just skip the header and consider it is raw
546
           audio data */
547
        if (len <= 3)
548
            goto skip;
549
        get_byte(s->pb); /* emphasis (1), muse(1), reserved(1), frame number(5) */
550
        b1 = get_byte(s->pb); /* quant (2), freq(2), reserved(1), channels(3) */
551
        get_byte(s->pb); /* dynamic range control (0x80 = off) */
552
        len -= 3;
553
        freq = (b1 >> 4) & 3;
554
        st->codec->sample_rate = lpcm_freq_tab[freq];
555
        st->codec->channels = 1 + (b1 & 7);
556
        st->codec->bits_per_coded_sample = 16 + ((b1 >> 6) & 3) * 4;
557
        st->codec->bit_rate = st->codec->channels *
558
                              st->codec->sample_rate *
559
                              st->codec->bits_per_coded_sample;
560
        if (st->codec->bits_per_coded_sample == 16)
561
            st->codec->codec_id = CODEC_ID_PCM_S16BE;
562
        else if (st->codec->bits_per_coded_sample == 28)
563
            return AVERROR(EINVAL);
564
    }
565
    av_new_packet(pkt, len);
566
    get_buffer(s->pb, pkt->data, pkt->size);
567
    pkt->pts = pts;
568
    pkt->dts = dts;
569
    pkt->pos = dummy_pos;
570
    pkt->stream_index = st->index;
571
#if 0
572
    av_log(s, AV_LOG_DEBUG, "%d: pts=%0.3f dts=%0.3f size=%d\n",
573
           pkt->stream_index, pkt->pts / 90000.0, pkt->dts / 90000.0, pkt->size);
574
#endif
575

    
576
    return 0;
577
}
578

    
579
static int64_t mpegps_read_dts(AVFormatContext *s, int stream_index,
580
                               int64_t *ppos, int64_t pos_limit)
581
{
582
    int len, startcode;
583
    int64_t pos, pts, dts;
584

    
585
    pos = *ppos;
586
#ifdef DEBUG_SEEK
587
    printf("read_dts: pos=0x%"PRIx64" next=%d -> ", pos, find_next);
588
#endif
589
    if (url_fseek(s->pb, pos, SEEK_SET) < 0)
590
        return AV_NOPTS_VALUE;
591

    
592
    for(;;) {
593
        len = mpegps_read_pes_header(s, &pos, &startcode, &pts, &dts);
594
        if (len < 0) {
595
#ifdef DEBUG_SEEK
596
            printf("none (ret=%d)\n", len);
597
#endif
598
            return AV_NOPTS_VALUE;
599
        }
600
        if (startcode == s->streams[stream_index]->id &&
601
            dts != AV_NOPTS_VALUE) {
602
            break;
603
        }
604
        url_fskip(s->pb, len);
605
    }
606
#ifdef DEBUG_SEEK
607
    printf("pos=0x%"PRIx64" dts=0x%"PRIx64" %0.3f\n", pos, dts, dts / 90000.0);
608
#endif
609
    *ppos = pos;
610
    return dts;
611
}
612

    
613
AVInputFormat mpegps_demuxer = {
614
    "mpeg",
615
    NULL_IF_CONFIG_SMALL("MPEG-PS format"),
616
    sizeof(MpegDemuxContext),
617
    mpegps_probe,
618
    mpegps_read_header,
619
    mpegps_read_packet,
620
    NULL,
621
    NULL, //mpegps_read_seek,
622
    mpegps_read_dts,
623
    .flags = AVFMT_SHOW_IDS|AVFMT_TS_DISCONT,
624
};