libavformat/dv.c

   1 /*
   2  * General DV demuxer
   3  * Copyright (c) 2003 Roman Shaposhnik
   4  *
   5  * Many thanks to Dan Dennedy <dan@dennedy.org> for providing wealth
   6  * of DV technical info.
   7  *
   8  * Raw DV format
   9  * Copyright (c) 2002 Fabrice Bellard
  10  *
  11  * 50 Mbps (DVCPRO50) and 100 Mbps (DVCPRO HD) support
  12  * Copyright (c) 2006 Daniel Maas <dmaas@maasdigital.com>
  13  * Funded by BBC Research & Development
  14  *
  15  * This file is part of FFmpeg.
  16  *
  17  * FFmpeg is free software; you can redistribute it and/or
  18  * modify it under the terms of the GNU Lesser General Public
  19  * License as published by the Free Software Foundation; either
  20  * version 2.1 of the License, or (at your option) any later version.
  21  *
  22  * FFmpeg is distributed in the hope that it will be useful,
  23  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  24  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  25  * Lesser General Public License for more details.
  26  *
  27  * You should have received a copy of the GNU Lesser General Public
  28  * License along with FFmpeg; if not, write to the Free Software
  29  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  30  */
  31
  32 #include "config_components.h"
  33
  34 #include <time.h>
  35 #include "avformat.h"
  36 #include "demux.h"
  37 #include "internal.h"
  38 #include "libavcodec/dv_profile.h"
  39 #include "libavcodec/dv.h"
  40 #include "libavutil/channel_layout.h"
  41 #include "libavutil/intreadwrite.h"
  42 #include "libavutil/mathematics.h"
  43 #include "libavutil/mem.h"
  44 #include "libavutil/timecode.h"
  45 #include "dv.h"
  46 #include "libavutil/avassert.h"
  47
  48 #if CONFIG_DV_DEMUXER
  49
  50 // Must be kept in sync with AVPacket
  51 typedef struct DVPacket {
  52     int64_t  pts;
  53     uint8_t *data;
  54     int      size;
  55     int      stream_index;
  56     int      flags;
  57     int64_t  pos;
  58     int64_t  duration;
  59
  60     int sample_rate;
  61     int last_sample_rate;
  62 } DVPacket;
  63
  64 struct DVDemuxContext {
  65     const AVDVProfile*  sys;    /* Current DV profile. E.g.: 525/60, 625/50 */
  66     AVFormatContext*  fctx;
  67     AVStream*         vst;
  68     AVStream*         ast[4];
  69     struct DVPacket   audio_pkt[4];
  70     uint8_t           audio_buf[4][8192];
  71     int               ach;
  72     int               frames;
  73
  74     int64_t           next_pts_video;
  75     int64_t           next_pts_audio;
  76 };
  77
  78 static inline uint16_t dv_audio_12to16(uint16_t sample)
  79 {
  80     uint16_t shift, result;
  81
  82     sample = (sample < 0x800) ? sample : sample | 0xf000;
  83     shift  = (sample & 0xf00) >> 8;
  84
  85     if (shift < 0x2 || shift > 0xd) {
  86         result = sample;
  87     } else if (shift < 0x8) {
  88         shift--;
  89         result = (sample - (256 * shift)) << shift;
  90     } else {
  91         shift  = 0xe - shift;
  92         result = ((sample + ((256 * shift) + 1)) << shift) - 1;
  93     }
  94
  95     return result;
  96 }
  97
  98 static const uint8_t *dv_extract_pack(const uint8_t *frame, enum DVPackType t)
  99 {
 100     int offs;
 101     int c;
 102
 103     for (c = 0; c < 10; c++) {
 104         switch (t) {
 105         case DV_AUDIO_SOURCE:
 106             if (c&1)    offs = (80 * 6 + 80 * 16 * 0 + 3 + c*12000);
 107             else        offs = (80 * 6 + 80 * 16 * 3 + 3 + c*12000);
 108             break;
 109         case DV_AUDIO_CONTROL:
 110             if (c&1)    offs = (80 * 6 + 80 * 16 * 1 + 3 + c*12000);
 111             else        offs = (80 * 6 + 80 * 16 * 4 + 3 + c*12000);
 112             break;
 113         case DV_VIDEO_CONTROL:
 114             if (c&1)    offs = (80 * 3 + 8      + c*12000);
 115             else        offs = (80 * 5 + 48 + 5 + c*12000);
 116             break;
 117         case DV_TIMECODE:
 118             offs = (80*1 + 3 + 3);
 119             break;
 120         default:
 121             return NULL;
 122         }
 123         if (frame[offs] == t)
 124             break;
 125     }
 126
 127     return frame[offs] == t ? &frame[offs] : NULL;
 128 }
 129
 130 static const int dv_audio_frequency[3] = {
 131     48000, 44100, 32000,
 132 };
 133
 134 /*
 135  * There's a couple of assumptions being made here:
 136  * 1. By default we silence erroneous (0x8000/16-bit 0x800/12-bit) audio samples.
 137  *    We can pass them upwards when libavcodec will be ready to deal with them.
 138  * 2. We don't do software emphasis.
 139  * 3. Audio is always returned as 16-bit linear samples: 12-bit nonlinear samples
 140  *    are converted into 16-bit linear ones.
 141  */
 142 static int dv_extract_audio(const uint8_t *frame, uint8_t **ppcm,
 143                             const AVDVProfile *sys)
 144 {
 145     int size, chan, i, j, d, of, smpls, freq, quant, half_ch;
 146     uint16_t lc, rc;
 147     const uint8_t *as_pack;
 148     uint8_t *pcm, ipcm;
 149
 150     as_pack = dv_extract_pack(frame, DV_AUDIO_SOURCE);
 151     if (!as_pack)    /* No audio ? */
 152         return 0;
 153
 154     smpls = as_pack[1]      & 0x3f; /* samples in this frame - min. samples */
 155     freq  = as_pack[4] >> 3 & 0x07; /* 0 - 48kHz, 1 - 44,1kHz, 2 - 32kHz */
 156     quant = as_pack[4]      & 0x07; /* 0 - 16-bit linear, 1 - 12-bit nonlinear */
 157
 158     if (quant > 1)
 159         return -1;  /* unsupported quantization */
 160
 161     if (freq >= FF_ARRAY_ELEMS(dv_audio_frequency))
 162         return AVERROR_INVALIDDATA;
 163
 164     size    = (sys->audio_min_samples[freq] + smpls) * 4; /* 2ch, 2bytes */
 165     half_ch = sys->difseg_size / 2;
 166
 167     /* We work with 720p frames split in half, thus even frames have
 168      * channels 0,1 and odd 2,3. */
 169     ipcm = (sys->height == 720 && !(frame[1] & 0x0C)) ? 2 : 0;
 170
 171     if (ipcm + sys->n_difchan > (quant == 1 ? 2 : 4)) {
 172         av_log(NULL, AV_LOG_ERROR, "too many dv pcm frames\n");
 173         return AVERROR_INVALIDDATA;
 174     }
 175
 176     /* for each DIF channel */
 177     for (chan = 0; chan < sys->n_difchan; chan++) {
 178         av_assert0(ipcm<4);
 179         pcm = ppcm[ipcm++];
 180         if (!pcm)
 181             break;
 182
 183         /* for each DIF segment */
 184         for (i = 0; i < sys->difseg_size; i++) {
 185             frame += 6 * 80; /* skip DIF segment header */
 186             if (quant == 1 && i == half_ch) {
 187                 /* next stereo channel (12-bit mode only) */
 188                 av_assert0(ipcm<4);
 189                 pcm = ppcm[ipcm++];
 190                 if (!pcm)
 191                     break;
 192             }
 193
 194             /* for each AV sequence */
 195             for (j = 0; j < 9; j++) {
 196                 for (d = 8; d < 80; d += 2) {
 197                     if (quant == 0) {  /* 16-bit quantization */
 198                         of = sys->audio_shuffle[i][j] +
 199                              (d - 8) / 2 * sys->audio_stride;
 200                         if (of * 2 >= size)
 201                             continue;
 202
 203                         /* FIXME: maybe we have to admit that DV is a
 204                          * big-endian PCM */
 205                         pcm[of * 2]     = frame[d + 1];
 206                         pcm[of * 2 + 1] = frame[d];
 207
 208                         if (pcm[of * 2 + 1] == 0x80 && pcm[of * 2] == 0x00)
 209                             pcm[of * 2 + 1] = 0;
 210                     } else {           /* 12-bit quantization */
 211                         lc = ((uint16_t)frame[d]     << 4) |
 212                              ((uint16_t)frame[d + 2] >> 4);
 213                         rc = ((uint16_t)frame[d + 1] << 4) |
 214                              ((uint16_t)frame[d + 2] & 0x0f);
 215                         lc = (lc == 0x800 ? 0 : dv_audio_12to16(lc));
 216                         rc = (rc == 0x800 ? 0 : dv_audio_12to16(rc));
 217
 218                         of = sys->audio_shuffle[i % half_ch][j] +
 219                              (d - 8) / 3 * sys->audio_stride;
 220                         if (of * 2 >= size)
 221                             continue;
 222
 223                         /* FIXME: maybe we have to admit that DV is a
 224                          * big-endian PCM */
 225                         pcm[of * 2]     = lc & 0xff;
 226                         pcm[of * 2 + 1] = lc >> 8;
 227                         of = sys->audio_shuffle[i % half_ch + half_ch][j] +
 228                              (d - 8) / 3 * sys->audio_stride;
 229                         /* FIXME: maybe we have to admit that DV is a
 230                          * big-endian PCM */
 231                         pcm[of * 2]     = rc & 0xff;
 232                         pcm[of * 2 + 1] = rc >> 8;
 233                         ++d;
 234                     }
 235                 }
 236
 237                 frame += 16 * 80; /* 15 Video DIFs + 1 Audio DIF */
 238             }
 239         }
 240     }
 241
 242     return size;
 243 }
 244
 245 static int dv_extract_audio_info(DVDemuxContext *c, const uint8_t *frame)
 246 {
 247     const uint8_t *as_pack;
 248     int freq, stype, smpls, quant, i, ach, sr;
 249
 250     as_pack = dv_extract_pack(frame, DV_AUDIO_SOURCE);
 251     if (!as_pack || !c->sys) {    /* No audio ? */
 252         c->ach = 0;
 253         return 0;
 254     }
 255
 256     smpls = as_pack[1]      & 0x3f; /* samples in this frame - min. samples */
 257     freq  = as_pack[4] >> 3 & 0x07; /* 0 - 48kHz, 1 - 44,1kHz, 2 - 32kHz */
 258     stype = as_pack[3]      & 0x1f; /* 0 - 2CH, 2 - 4CH, 3 - 8CH */
 259     quant = as_pack[4]      & 0x07; /* 0 - 16-bit linear, 1 - 12-bit nonlinear */
 260
 261     if (freq >= FF_ARRAY_ELEMS(dv_audio_frequency)) {
 262         av_log(c->fctx, AV_LOG_ERROR,
 263                "Unrecognized audio sample rate index (%d)\n", freq);
 264         return 0;
 265     }
 266     sr = dv_audio_frequency[freq];
 267
 268     if (stype > 3) {
 269         av_log(c->fctx, AV_LOG_ERROR, "stype %d is invalid\n", stype);
 270         c->ach = 0;
 271         return 0;
 272     }
 273
 274     /* note: ach counts PAIRS of channels (i.e. stereo channels) */
 275     ach = ((int[4]) { 1, 0, 2, 4 })[stype];
 276     if (ach == 1 && quant && freq == 2)
 277         ach = 2;
 278
 279     /* Dynamic handling of the audio streams in DV */
 280     c->ach = 0;
 281     for (i = 0; i < ach; i++) {
 282         if (!c->ast[i]) {
 283             c->ast[i] = avformat_new_stream(c->fctx, NULL);
 284             if (!c->ast[i])
 285                 return AVERROR(ENOMEM);
 286
 287             avpriv_set_pts_info(c->ast[i], 64, 1, DV_TIMESCALE_AUDIO);
 288             c->ast[i]->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
 289             c->ast[i]->codecpar->codec_id   = AV_CODEC_ID_PCM_S16LE;
 290             c->ast[i]->codecpar->ch_layout  = (AVChannelLayout)AV_CHANNEL_LAYOUT_STEREO;
 291             c->ast[i]->start_time           = 0;
 292             c->ast[i]->codecpar->bit_rate   = 2 * sr * 16;
 293
 294             c->ast[i]->codecpar->sample_rate = sr;
 295             c->audio_pkt[i].last_sample_rate = sr;
 296
 297             c->audio_pkt[i].size         = 0;
 298             c->audio_pkt[i].data         = c->audio_buf[i];
 299             c->audio_pkt[i].stream_index = c->ast[i]->index;
 300             c->audio_pkt[i].flags       |= AV_PKT_FLAG_KEY;
 301             c->audio_pkt[i].pts          = AV_NOPTS_VALUE;
 302             c->audio_pkt[i].duration     = 0;
 303             c->audio_pkt[i].pos          = -1;
 304         }
 305
 306         c->audio_pkt[i].sample_rate = sr;
 307     }
 308     c->ach = ach;
 309
 310     return (c->sys->audio_min_samples[freq] + smpls) * 4; /* 2ch, 2bytes */
 311 }
 312
 313 static int dv_extract_video_info(DVDemuxContext *c, const uint8_t *frame)
 314 {
 315     const uint8_t *vsc_pack;
 316     AVCodecParameters *par;
 317     int apt, is16_9;
 318
 319     par = c->vst->codecpar;
 320
 321     c->vst->avg_frame_rate = av_inv_q(c->vst->time_base);
 322
 323     /* finding out SAR is a little bit messy */
 324     vsc_pack = dv_extract_pack(frame, DV_VIDEO_CONTROL);
 325     apt      = frame[4] & 0x07;
 326     is16_9   = (vsc_pack && ((vsc_pack[2] & 0x07) == 0x02 ||
 327                              (!apt && (vsc_pack[2] & 0x07) == 0x07)));
 328     c->vst->sample_aspect_ratio = c->sys->sar[is16_9];
 329     par->bit_rate = av_rescale_q(c->sys->frame_size,
 330                                    (AVRational) { 8, 1 },
 331                                    c->sys->time_base);
 332     return c->sys->frame_size;
 333 }
 334
 335 static int dv_extract_timecode(DVDemuxContext* c, const uint8_t* frame, char *tc)
 336 {
 337     const uint8_t *tc_pack;
 338
 339     // For PAL systems, drop frame bit is replaced by an arbitrary
 340     // bit so its value should not be considered. Drop frame timecode
 341     // is only relevant for NTSC systems.
 342     int prevent_df = c->sys->ltc_divisor == 25 || c->sys->ltc_divisor == 50;
 343
 344     tc_pack = dv_extract_pack(frame, DV_TIMECODE);
 345     if (!tc_pack)
 346         return 0;
 347     av_timecode_make_smpte_tc_string2(tc, av_inv_q(c->sys->time_base), AV_RB32(tc_pack + 1), prevent_df, 1);
 348     return 1;
 349 }
 350
 351 /* The following 3 functions constitute our interface to the world */
 352
 353 static int dv_init_demux(AVFormatContext *s, DVDemuxContext *c)
 354 {
 355     c->vst = avformat_new_stream(s, NULL);
 356     if (!c->vst)
 357         return AVERROR(ENOMEM);
 358
 359     c->fctx                   = s;
 360     c->vst->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
 361     c->vst->codecpar->codec_id   = AV_CODEC_ID_DVVIDEO;
 362     c->vst->start_time        = 0;
 363
 364     avpriv_set_pts_info(c->vst, 64, 1, DV_TIMESCALE_VIDEO);
 365
 366     /* Audio streams are added later as they are encountered. */
 367     s->ctx_flags |= AVFMTCTX_NOHEADER;
 368
 369     return 0;
 370 }
 371
 372 DVDemuxContext *avpriv_dv_init_demux(AVFormatContext *s)
 373 {
 374     DVDemuxContext *c;
 375
 376     c = av_mallocz(sizeof(DVDemuxContext));
 377     if (!c)
 378         return NULL;
 379
 380     if (dv_init_demux(s, c)) {
 381         av_free(c);
 382         return NULL;
 383     }
 384
 385     return c;
 386 }
 387
 388 int avpriv_dv_get_packet(DVDemuxContext *c, AVPacket *pkt)
 389 {
 390     int size = -1;
 391     int i;
 392
 393     for (i = 0; i < c->ach; i++) {
 394         if (c->ast[i] && c->audio_pkt[i].size) {
 395             DVPacket *dpkt = &c->audio_pkt[i];
 396
 397             pkt->size         = dpkt->size;
 398             pkt->data         = dpkt->data;
 399             pkt->stream_index = dpkt->stream_index;
 400             pkt->flags        = dpkt->flags;
 401             pkt->pts          = dpkt->pts;
 402             pkt->duration     = dpkt->duration;
 403             pkt->pos          = dpkt->pos;
 404
 405             dpkt->size = 0;
 406             size       = pkt->size;
 407
 408             if (dpkt->last_sample_rate != dpkt->sample_rate) {
 409                 int ret = ff_add_param_change(pkt, 0, 0, dpkt->sample_rate, 0, 0);
 410                 if (ret < 0)
 411                     return ret;
 412                 dpkt->last_sample_rate = dpkt->sample_rate;
 413             }
 414
 415             break;
 416         }
 417     }
 418
 419     return size;
 420 }
 421
 422 int avpriv_dv_produce_packet(DVDemuxContext *c, AVPacket *pkt,
 423                              uint8_t *buf, int buf_size, int64_t pos)
 424 {
 425     int64_t pts, duration;
 426     int size, i;
 427     uint8_t *ppcm[5] = { 0 };
 428
 429     if (buf_size < DV_PROFILE_BYTES ||
 430         !(c->sys = av_dv_frame_profile(c->sys, buf, buf_size)) ||
 431         buf_size < c->sys->frame_size) {
 432         return AVERROR_INVALIDDATA;
 433     }
 434
 435     /* Queueing audio packet */
 436     /* FIXME: in case of no audio/bad audio we have to do something */
 437     size = dv_extract_audio_info(c, buf);
 438     if (size < 0)
 439         return size;
 440
 441     if (c->ach) {
 442         int64_t next_pts_video = av_rescale_q(c->next_pts_video, c->vst->time_base,
 443                                               c->ast[0]->time_base);
 444
 445         duration = av_rescale_q(size / 4,
 446                                 (AVRational){ 1, c->audio_pkt[0].sample_rate },
 447                                 c->ast[0]->time_base);
 448
 449         // if audio timestamps are more than one frame away from video,
 450         // assume desync happened (e.g. due to dropped audio frames) and
 451         // resynchronize
 452         pts = (FFABS(next_pts_video - c->next_pts_audio) >= duration) ?
 453               next_pts_video : c->next_pts_audio;
 454
 455         c->next_pts_audio = pts + duration;
 456     }
 457
 458     for (i = 0; i < c->ach; i++) {
 459         DVPacket *dpkt = &c->audio_pkt[i];
 460
 461         dpkt->pos      = pos;
 462         dpkt->size     = size;
 463         dpkt->pts      = pts;
 464         dpkt->duration = duration;
 465
 466         ppcm[i] = c->audio_buf[i];
 467     }
 468     if (c->ach)
 469         dv_extract_audio(buf, ppcm, c->sys);
 470
 471     /* We work with 720p frames split in half, thus even frames have
 472      * channels 0,1 and odd 2,3. */
 473     if (c->sys->height == 720) {
 474         if (buf[1] & 0x0C) {
 475             c->audio_pkt[2].size = c->audio_pkt[3].size = 0;
 476         } else {
 477             c->audio_pkt[0].size = c->audio_pkt[1].size = 0;
 478         }
 479     }
 480
 481     /* return the video packet, if the caller wants it */
 482     if (pkt) {
 483         size = dv_extract_video_info(c, buf);
 484
 485         pkt->data         = buf;
 486         pkt->pos          = pos;
 487         pkt->size         = size;
 488         pkt->flags       |= AV_PKT_FLAG_KEY;
 489         pkt->stream_index = c->vst->index;
 490         pkt->pts          = c->next_pts_video;
 491         pkt->duration     = av_rescale_q(1, c->sys->time_base, c->vst->time_base);
 492
 493         c->next_pts_video += pkt->duration;
 494     }
 495
 496     c->frames++;
 497
 498     return size;
 499 }
 500
 501 static int64_t dv_frame_offset(AVFormatContext *s, DVDemuxContext *c,
 502                                int64_t *timestamp)
 503 {
 504     // FIXME: sys may be wrong if last dv_read_packet() failed (buffer is junk)
 505     FFFormatContext *const si = ffformatcontext(s);
 506     const int frame_size = c->sys->frame_size;
 507     int64_t  frame_count = av_rescale_q(*timestamp, c->vst->time_base, c->sys->time_base);
 508     int64_t offset;
 509     int64_t size       = avio_size(s->pb) - si->data_offset;
 510     int64_t max_offset = ((size - 1) / frame_size) * frame_size;
 511
 512     offset = frame_size * frame_count;
 513
 514     if (size >= 0 && offset > max_offset)
 515         offset = max_offset;
 516     else if (offset < 0)
 517         offset = 0;
 518
 519     *timestamp = av_rescale_q(offset / frame_size, c->sys->time_base, c->vst->time_base);
 520
 521     return offset + si->data_offset;
 522 }
 523
 524 void ff_dv_ts_reset(DVDemuxContext *c, int64_t ts)
 525 {
 526     c->frames         = !c->sys ? 0 :
 527                         av_rescale_q(ts, c->vst->time_base, c->sys->time_base);
 528     c->next_pts_video = ts;
 529     c->next_pts_audio = (!c->sys || !c->ast[0]) ? AV_NOPTS_VALUE :
 530                         av_rescale_q(ts, c->vst->time_base, c->ast[0]->time_base);
 531
 532     c->audio_pkt[0].size = c->audio_pkt[1].size = 0;
 533     c->audio_pkt[2].size = c->audio_pkt[3].size = 0;
 534 }
 535
 536 /************************************************************
 537  * Implementation of the easiest DV storage of all -- raw DV.
 538  ************************************************************/
 539
 540 typedef struct RawDVContext {
 541     DVDemuxContext  dv_demux;
 542     uint8_t         buf[DV_MAX_FRAME_SIZE];
 543 } RawDVContext;
 544
 545 static int dv_read_timecode(AVFormatContext *s) {
 546     int ret;
 547     char timecode[AV_TIMECODE_STR_SIZE];
 548     int64_t pos = avio_tell(s->pb);
 549
 550     // Read 3 DIF blocks: Header block and 2 Subcode blocks.
 551 #define PARTIAL_FRAME_SIZE (3 * 80)
 552     uint8_t partial_frame[PARTIAL_FRAME_SIZE];
 553     RawDVContext *c = s->priv_data;
 554
 555     ret = avio_read(s->pb, partial_frame, PARTIAL_FRAME_SIZE);
 556     if (ret < 0)
 557         goto finish;
 558
 559     if (ret < PARTIAL_FRAME_SIZE) {
 560         ret = -1;
 561         goto finish;
 562     }
 563
 564     ret = dv_extract_timecode(&c->dv_demux, partial_frame, timecode);
 565     if (ret)
 566         av_dict_set(&s->metadata, "timecode", timecode, 0);
 567     else
 568         av_log(s, AV_LOG_ERROR, "Detected timecode is invalid\n");
 569
 570 finish:
 571     avio_seek(s->pb, pos, SEEK_SET);
 572     return ret;
 573 }
 574
 575 static int dv_read_header(AVFormatContext *s)
 576 {
 577     unsigned state, marker_pos = 0;
 578     RawDVContext *c = s->priv_data;
 579     int ret;
 580
 581     if ((ret = dv_init_demux(s, &c->dv_demux)) < 0)
 582         return ret;
 583
 584     state = avio_rb32(s->pb);
 585     while ((state & 0xffffff7f) != 0x1f07003f) {
 586         if (avio_feof(s->pb)) {
 587             av_log(s, AV_LOG_ERROR, "Cannot find DV header.\n");
 588             return AVERROR_INVALIDDATA;
 589         }
 590         if (state == 0x003f0700 || state == 0xff3f0700)
 591             marker_pos = avio_tell(s->pb);
 592         if (state == 0xff3f0701 && avio_tell(s->pb) - marker_pos == 80) {
 593             avio_seek(s->pb, -163, SEEK_CUR);
 594             state = avio_rb32(s->pb);
 595             break;
 596         }
 597         state = (state << 8) | avio_r8(s->pb);
 598     }
 599     AV_WB32(c->buf, state);
 600
 601     if (avio_read(s->pb, c->buf + 4, DV_PROFILE_BYTES - 4) != DV_PROFILE_BYTES - 4 ||
 602         avio_seek(s->pb, -DV_PROFILE_BYTES, SEEK_CUR) < 0) {
 603         return AVERROR(EIO);
 604     }
 605
 606     c->dv_demux.sys = av_dv_frame_profile(c->dv_demux.sys,
 607                                            c->buf,
 608                                            DV_PROFILE_BYTES);
 609     if (!c->dv_demux.sys) {
 610         av_log(s, AV_LOG_ERROR,
 611                "Can't determine profile of DV input stream.\n");
 612         return AVERROR_INVALIDDATA;
 613     }
 614
 615     s->bit_rate = av_rescale_q(c->dv_demux.sys->frame_size,
 616                                (AVRational) { 8, 1 },
 617                                c->dv_demux.sys->time_base);
 618
 619     if (s->pb->seekable & AVIO_SEEKABLE_NORMAL)
 620         dv_read_timecode(s);
 621
 622     return 0;
 623 }
 624
 625 static int dv_read_packet(AVFormatContext *s, AVPacket *pkt)
 626 {
 627     int size;
 628     RawDVContext *c = s->priv_data;
 629
 630     size = avpriv_dv_get_packet(&c->dv_demux, pkt);
 631
 632     if (size < 0) {
 633         int ret;
 634         int64_t pos = avio_tell(s->pb);
 635         if (!c->dv_demux.sys)
 636             return AVERROR(EIO);
 637         size = c->dv_demux.sys->frame_size;
 638         ret = avio_read(s->pb, c->buf, size);
 639         if (ret < 0) {
 640             return ret;
 641         } else if (ret == 0) {
 642             return AVERROR(EIO);
 643         }
 644
 645         size = avpriv_dv_produce_packet(&c->dv_demux, pkt, c->buf, size, pos);
 646     }
 647
 648     return size;
 649 }
 650
 651 static int dv_read_seek(AVFormatContext *s, int stream_index,
 652                         int64_t timestamp, int flags)
 653 {
 654     RawDVContext *r   = s->priv_data;
 655     DVDemuxContext *c = &r->dv_demux;
 656     int64_t offset;
 657
 658     // seek using the video stream
 659     if (stream_index != c->vst->index)
 660         timestamp = av_rescale_q(timestamp, s->streams[stream_index]->time_base,
 661                                  c->vst->time_base);
 662
 663     offset = dv_frame_offset(s, c, &timestamp);
 664
 665     if (avio_seek(s->pb, offset, SEEK_SET) < 0)
 666         return -1;
 667
 668     ff_dv_ts_reset(c, timestamp);
 669     return 0;
 670 }
 671
 672 static int dv_probe(const AVProbeData *p)
 673 {
 674     unsigned marker_pos = 0;
 675     int i;
 676     int matches           = 0;
 677     int firstmatch        = 0;
 678     int secondary_matches = 0;
 679
 680     if (p->buf_size < 5)
 681         return 0;
 682
 683     for (i = 0; i < p->buf_size-4; i++) {
 684         unsigned state = AV_RB32(p->buf+i);
 685         if ((state & 0x0007f840) == 0x00070000) {
 686             // any section header, also with seq/chan num != 0,
 687             // should appear around every 12000 bytes, at least 10 per frame
 688             if ((state & 0xff07ff7f) == 0x1f07003f) {
 689                 secondary_matches++;
 690                 if ((state & 0xffffff7f) == 0x1f07003f) {
 691                     matches++;
 692                     if (!i)
 693                         firstmatch = 1;
 694                 }
 695             }
 696             if (state == 0x003f0700 || state == 0xff3f0700)
 697                 marker_pos = i;
 698             if (state == 0xff3f0701 && i - marker_pos == 80)
 699                 matches++;
 700         }
 701     }
 702
 703     if (matches && p->buf_size / matches < 1024 * 1024) {
 704         if (matches > 4 || firstmatch ||
 705             (secondary_matches >= 10 &&
 706              p->buf_size / secondary_matches < 24000))
 707             // not max to avoid dv in mov to match
 708             return AVPROBE_SCORE_MAX * 3 / 4;
 709         return AVPROBE_SCORE_MAX / 4;
 710     }
 711     return 0;
 712 }
 713
 714 const FFInputFormat ff_dv_demuxer = {
 715     .p.name         = "dv",
 716     .p.long_name    = NULL_IF_CONFIG_SMALL("DV (Digital Video)"),
 717     .p.extensions   = "dv,dif",
 718     .priv_data_size = sizeof(RawDVContext),
 719     .read_probe     = dv_probe,
 720     .read_header    = dv_read_header,
 721     .read_packet    = dv_read_packet,
 722     .read_seek      = dv_read_seek,
 723 };
 724
 725 #else // CONFIG_DV_DEMUXER
 726 DVDemuxContext *avpriv_dv_init_demux(AVFormatContext *s)
 727 {
 728     return NULL;
 729 }
 730
 731 int avpriv_dv_get_packet(DVDemuxContext *c, AVPacket *pkt)
 732 {
 733     return AVERROR(ENOSYS);
 734 }
 735
 736 int avpriv_dv_produce_packet(DVDemuxContext *c, AVPacket *pkt,
 737                              uint8_t *buf, int buf_size, int64_t pos)
 738 {
 739     return AVERROR(ENOSYS);
 740 }
 741 #endif // CONFIG_DV_DEMUXER