media/filters/ffmpeg_demuxer.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "media/filters/ffmpeg_demuxer.h"
   6
   7 #include <algorithm>
   8
   9 #include "base/base64.h"
  10 #include "base/bind.h"
  11 #include "base/callback_helpers.h"
  12 #include "base/memory/scoped_ptr.h"
  13 #include "base/metrics/sparse_histogram.h"
  14 #include "base/single_thread_task_runner.h"
  15 #include "base/strings/string_number_conversions.h"
  16 #include "base/strings/string_util.h"
  17 #include "base/strings/stringprintf.h"
  18 #include "base/sys_byteorder.h"
  19 #include "base/task_runner_util.h"
  20 #include "base/thread_task_runner_handle.h"
  21 #include "base/time/time.h"
  22 #include "media/base/bind_to_current_loop.h"
  23 #include "media/base/decrypt_config.h"
  24 #include "media/base/limits.h"
  25 #include "media/base/media_log.h"
  26 #include "media/ffmpeg/ffmpeg_common.h"
  27 #include "media/filters/ffmpeg_aac_bitstream_converter.h"
  28 #include "media/filters/ffmpeg_bitstream_converter.h"
  29 #include "media/filters/ffmpeg_glue.h"
  30 #include "media/filters/ffmpeg_h264_to_annex_b_bitstream_converter.h"
  31 #include "media/filters/webvtt_util.h"
  32 #include "media/formats/webm/webm_crypto_helpers.h"
  33
  34 namespace media {
  35
  36 static base::Time ExtractTimelineOffset(AVFormatContext* format_context) {
  37   if (strstr(format_context->iformat->name, "webm") ||
  38       strstr(format_context->iformat->name, "matroska")) {
  39     const AVDictionaryEntry* entry =
  40         av_dict_get(format_context->metadata, "creation_time", NULL, 0);
  41
  42     base::Time timeline_offset;
  43     if (entry != NULL && entry->value != NULL &&
  44         FFmpegUTCDateToTime(entry->value, &timeline_offset)) {
  45       return timeline_offset;
  46     }
  47   }
  48
  49   return base::Time();
  50 }
  51
  52 static base::TimeDelta FramesToTimeDelta(int frames, double sample_rate) {
  53   return base::TimeDelta::FromMicroseconds(
  54       frames * base::Time::kMicrosecondsPerSecond / sample_rate);
  55 }
  56
  57 static base::TimeDelta ExtractStartTime(AVStream* stream,
  58                                         base::TimeDelta start_time_estimate) {
  59   DCHECK(start_time_estimate != kNoTimestamp());
  60   if (stream->start_time == static_cast<int64_t>(AV_NOPTS_VALUE)) {
  61     return start_time_estimate == kInfiniteDuration() ? kNoTimestamp()
  62                                                       : start_time_estimate;
  63   }
  64
  65   // First try the lower of the estimate and the |start_time| value.
  66   base::TimeDelta start_time =
  67       std::min(ConvertFromTimeBase(stream->time_base, stream->start_time),
  68                start_time_estimate);
  69
  70   // Next see if the first buffered pts value is usable.
  71   if (stream->pts_buffer[0] != static_cast<int64_t>(AV_NOPTS_VALUE)) {
  72     const base::TimeDelta buffered_pts =
  73         ConvertFromTimeBase(stream->time_base, stream->pts_buffer[0]);
  74     if (buffered_pts < start_time)
  75       start_time = buffered_pts;
  76   }
  77
  78   // NOTE: Do not use AVStream->first_dts since |start_time| should be a
  79   // presentation timestamp.
  80   return start_time;
  81 }
  82
  83 //
  84 // FFmpegDemuxerStream
  85 //
  86 FFmpegDemuxerStream::FFmpegDemuxerStream(FFmpegDemuxer* demuxer,
  87                                          AVStream* stream)
  88     : demuxer_(demuxer),
  89       task_runner_(base::ThreadTaskRunnerHandle::Get()),
  90       stream_(stream),
  91       type_(UNKNOWN),
  92       liveness_(LIVENESS_UNKNOWN),
  93       end_of_stream_(false),
  94       last_packet_timestamp_(kNoTimestamp()),
  95       last_packet_duration_(kNoTimestamp()),
  96       video_rotation_(VIDEO_ROTATION_0),
  97       fixup_negative_ogg_timestamps_(false) {
  98   DCHECK(demuxer_);
  99
 100   bool is_encrypted = false;
 101   int rotation = 0;
 102   AVDictionaryEntry* rotation_entry = NULL;
 103
 104   // Determine our media format.
 105   switch (stream->codec->codec_type) {
 106     case AVMEDIA_TYPE_AUDIO:
 107       type_ = AUDIO;
 108       AVStreamToAudioDecoderConfig(stream, &audio_config_, true);
 109       is_encrypted = audio_config_.is_encrypted();
 110       break;
 111     case AVMEDIA_TYPE_VIDEO:
 112       type_ = VIDEO;
 113       AVStreamToVideoDecoderConfig(stream, &video_config_, true);
 114       is_encrypted = video_config_.is_encrypted();
 115
 116       rotation_entry = av_dict_get(stream->metadata, "rotate", NULL, 0);
 117       if (rotation_entry && rotation_entry->value && rotation_entry->value[0])
 118         base::StringToInt(rotation_entry->value, &rotation);
 119
 120       switch (rotation) {
 121         case 0:
 122           break;
 123         case 90:
 124           video_rotation_ = VIDEO_ROTATION_90;
 125           break;
 126         case 180:
 127           video_rotation_ = VIDEO_ROTATION_180;
 128           break;
 129         case 270:
 130           video_rotation_ = VIDEO_ROTATION_270;
 131           break;
 132         default:
 133           LOG(ERROR) << "Unsupported video rotation metadata: " << rotation;
 134           break;
 135       }
 136
 137       break;
 138     case AVMEDIA_TYPE_SUBTITLE:
 139       type_ = TEXT;
 140       break;
 141     default:
 142       NOTREACHED();
 143       break;
 144   }
 145
 146   // Calculate the duration.
 147   duration_ = ConvertStreamTimestamp(stream->time_base, stream->duration);
 148
 149   if (is_encrypted) {
 150     AVDictionaryEntry* key = av_dict_get(stream->metadata, "enc_key_id", NULL,
 151                                          0);
 152     DCHECK(key);
 153     DCHECK(key->value);
 154     if (!key || !key->value)
 155       return;
 156     base::StringPiece base64_key_id(key->value);
 157     std::string enc_key_id;
 158     base::Base64Decode(base64_key_id, &enc_key_id);
 159     DCHECK(!enc_key_id.empty());
 160     if (enc_key_id.empty())
 161       return;
 162
 163     encryption_key_id_.assign(enc_key_id);
 164     demuxer_->OnEncryptedMediaInitData(EmeInitDataType::WEBM, enc_key_id);
 165   }
 166 }
 167
 168 FFmpegDemuxerStream::~FFmpegDemuxerStream() {
 169   DCHECK(!demuxer_);
 170   DCHECK(read_cb_.is_null());
 171   DCHECK(buffer_queue_.IsEmpty());
 172 }
 173
 174 void FFmpegDemuxerStream::EnqueuePacket(ScopedAVPacket packet) {
 175   DCHECK(task_runner_->BelongsToCurrentThread());
 176
 177   if (!demuxer_ || end_of_stream_) {
 178     NOTREACHED() << "Attempted to enqueue packet on a stopped stream";
 179     return;
 180   }
 181
 182 #if defined(USE_PROPRIETARY_CODECS)
 183   // Convert the packet if there is a bitstream filter.
 184   if (packet->data && bitstream_converter_ &&
 185       !bitstream_converter_->ConvertPacket(packet.get())) {
 186     LOG(ERROR) << "Format conversion failed.";
 187   }
 188 #endif
 189
 190   // Get side data if any. For now, the only type of side_data is VP8 Alpha. We
 191   // keep this generic so that other side_data types in the future can be
 192   // handled the same way as well.
 193   av_packet_split_side_data(packet.get());
 194
 195   scoped_refptr<DecoderBuffer> buffer;
 196
 197   if (type() == DemuxerStream::TEXT) {
 198     int id_size = 0;
 199     uint8* id_data = av_packet_get_side_data(
 200         packet.get(),
 201         AV_PKT_DATA_WEBVTT_IDENTIFIER,
 202         &id_size);
 203
 204     int settings_size = 0;
 205     uint8* settings_data = av_packet_get_side_data(
 206         packet.get(),
 207         AV_PKT_DATA_WEBVTT_SETTINGS,
 208         &settings_size);
 209
 210     std::vector<uint8> side_data;
 211     MakeSideData(id_data, id_data + id_size,
 212                  settings_data, settings_data + settings_size,
 213                  &side_data);
 214
 215     buffer = DecoderBuffer::CopyFrom(packet.get()->data, packet.get()->size,
 216                                      side_data.data(), side_data.size());
 217   } else {
 218     int side_data_size = 0;
 219     uint8* side_data = av_packet_get_side_data(
 220         packet.get(),
 221         AV_PKT_DATA_MATROSKA_BLOCKADDITIONAL,
 222         &side_data_size);
 223
 224     scoped_ptr<DecryptConfig> decrypt_config;
 225     int data_offset = 0;
 226     if ((type() == DemuxerStream::AUDIO && audio_config_.is_encrypted()) ||
 227         (type() == DemuxerStream::VIDEO && video_config_.is_encrypted())) {
 228       if (!WebMCreateDecryptConfig(
 229           packet->data, packet->size,
 230           reinterpret_cast<const uint8*>(encryption_key_id_.data()),
 231           encryption_key_id_.size(),
 232           &decrypt_config,
 233           &data_offset)) {
 234         LOG(ERROR) << "Creation of DecryptConfig failed.";
 235       }
 236     }
 237
 238     // If a packet is returned by FFmpeg's av_parser_parse2() the packet will
 239     // reference inner memory of FFmpeg.  As such we should transfer the packet
 240     // into memory we control.
 241     if (side_data_size > 0) {
 242       buffer = DecoderBuffer::CopyFrom(packet.get()->data + data_offset,
 243                                        packet.get()->size - data_offset,
 244                                        side_data, side_data_size);
 245     } else {
 246       buffer = DecoderBuffer::CopyFrom(packet.get()->data + data_offset,
 247                                        packet.get()->size - data_offset);
 248     }
 249
 250     int skip_samples_size = 0;
 251     const uint32* skip_samples_ptr =
 252         reinterpret_cast<const uint32*>(av_packet_get_side_data(
 253             packet.get(), AV_PKT_DATA_SKIP_SAMPLES, &skip_samples_size));
 254     const int kSkipSamplesValidSize = 10;
 255     const int kSkipEndSamplesOffset = 1;
 256     if (skip_samples_size >= kSkipSamplesValidSize) {
 257       // Because FFmpeg rolls codec delay and skip samples into one we can only
 258       // allow front discard padding on the first buffer.  Otherwise the discard
 259       // helper can't figure out which data to discard.  See AudioDiscardHelper.
 260       int discard_front_samples = base::ByteSwapToLE32(*skip_samples_ptr);
 261       if (last_packet_timestamp_ != kNoTimestamp() && discard_front_samples) {
 262         DLOG(ERROR) << "Skip samples are only allowed for the first packet.";
 263         discard_front_samples = 0;
 264       }
 265
 266       const int discard_end_samples =
 267           base::ByteSwapToLE32(*(skip_samples_ptr + kSkipEndSamplesOffset));
 268       const int samples_per_second =
 269           audio_decoder_config().samples_per_second();
 270       buffer->set_discard_padding(std::make_pair(
 271           FramesToTimeDelta(discard_front_samples, samples_per_second),
 272           FramesToTimeDelta(discard_end_samples, samples_per_second)));
 273     }
 274
 275     if (decrypt_config)
 276       buffer->set_decrypt_config(decrypt_config.Pass());
 277   }
 278
 279   if (packet->duration >= 0) {
 280     buffer->set_duration(
 281         ConvertStreamTimestamp(stream_->time_base, packet->duration));
 282   } else {
 283     // TODO(wolenetz): Remove when FFmpeg stops returning negative durations.
 284     // https://crbug.com/394418
 285     DVLOG(1) << "FFmpeg returned a buffer with a negative duration! "
 286              << packet->duration;
 287     buffer->set_duration(kNoTimestamp());
 288   }
 289
 290   // Note: If pts is AV_NOPTS_VALUE, stream_timestamp will be kNoTimestamp().
 291   const base::TimeDelta stream_timestamp =
 292       ConvertStreamTimestamp(stream_->time_base, packet->pts);
 293
 294   if (stream_timestamp != kNoTimestamp()) {
 295     const bool is_audio = type() == AUDIO;
 296
 297     // If this is an OGG file with negative timestamps don't rebase any other
 298     // stream types against the negative starting time.
 299     base::TimeDelta start_time = demuxer_->start_time();
 300     if (fixup_negative_ogg_timestamps_ && !is_audio &&
 301         start_time < base::TimeDelta()) {
 302       start_time = base::TimeDelta();
 303     }
 304
 305     // Don't rebase timestamps for positive start times, the HTML Media Spec
 306     // details this in section "4.8.10.6 Offsets into the media resource." We
 307     // will still need to rebase timestamps before seeking with FFmpeg though.
 308     if (start_time > base::TimeDelta())
 309       start_time = base::TimeDelta();
 310
 311     buffer->set_timestamp(stream_timestamp - start_time);
 312
 313     // If enabled, mark audio packets with negative timestamps for post-decode
 314     // discard.
 315     if (fixup_negative_ogg_timestamps_ && is_audio &&
 316         stream_timestamp < base::TimeDelta() &&
 317         buffer->duration() != kNoTimestamp()) {
 318       if (stream_timestamp + buffer->duration() < base::TimeDelta()) {
 319         // Discard the entire packet if it's entirely before zero.
 320         buffer->set_discard_padding(
 321             std::make_pair(kInfiniteDuration(), base::TimeDelta()));
 322       } else {
 323         // Only discard part of the frame if it overlaps zero.
 324         buffer->set_discard_padding(
 325             std::make_pair(-stream_timestamp, base::TimeDelta()));
 326       }
 327     }
 328   } else {
 329     // If this happens on the first packet, decoders will throw an error.
 330     buffer->set_timestamp(kNoTimestamp());
 331   }
 332
 333   if (last_packet_timestamp_ != kNoTimestamp()) {
 334     // FFmpeg doesn't support chained ogg correctly.  Instead of guaranteeing
 335     // continuity across links in the chain it uses the timestamp information
 336     // from each link directly.  Doing so can lead to timestamps which appear to
 337     // go backwards in time.
 338     //
 339     // If the new link starts with a negative timestamp or a timestamp less than
 340     // the original (positive) |start_time|, we will get a negative timestamp
 341     // here.  It's also possible FFmpeg returns kNoTimestamp() here if it's not
 342     // able to work out a timestamp using the previous link and the next.
 343     //
 344     // Fixing chained ogg is non-trivial, so for now just reuse the last good
 345     // timestamp.  The decoder will rewrite the timestamps to be sample accurate
 346     // later.  See http://crbug.com/396864.
 347     if (fixup_negative_ogg_timestamps_ &&
 348         (buffer->timestamp() == kNoTimestamp() ||
 349          buffer->timestamp() < last_packet_timestamp_)) {
 350       buffer->set_timestamp(last_packet_timestamp_ +
 351                             (last_packet_duration_ != kNoTimestamp()
 352                                  ? last_packet_duration_
 353                                  : base::TimeDelta::FromMicroseconds(1)));
 354     }
 355
 356     // The demuxer should always output positive timestamps.
 357     DCHECK(buffer->timestamp() >= base::TimeDelta());
 358     DCHECK(buffer->timestamp() != kNoTimestamp());
 359
 360     if (last_packet_timestamp_ < buffer->timestamp()) {
 361       buffered_ranges_.Add(last_packet_timestamp_, buffer->timestamp());
 362       demuxer_->NotifyBufferingChanged();
 363     }
 364   }
 365
 366   if (packet.get()->flags & AV_PKT_FLAG_KEY)
 367     buffer->set_is_key_frame(true);
 368
 369   last_packet_timestamp_ = buffer->timestamp();
 370   last_packet_duration_ = buffer->duration();
 371
 372   buffer_queue_.Push(buffer);
 373   SatisfyPendingRead();
 374 }
 375
 376 void FFmpegDemuxerStream::SetEndOfStream() {
 377   DCHECK(task_runner_->BelongsToCurrentThread());
 378   end_of_stream_ = true;
 379   SatisfyPendingRead();
 380 }
 381
 382 void FFmpegDemuxerStream::FlushBuffers() {
 383   DCHECK(task_runner_->BelongsToCurrentThread());
 384   DCHECK(read_cb_.is_null()) << "There should be no pending read";
 385
 386   // H264 and AAC require that we resend the header after flush.
 387   // Reset bitstream for converter to do so.
 388   // This is related to chromium issue 140371 (http://crbug.com/140371).
 389   ResetBitstreamConverter();
 390
 391   buffer_queue_.Clear();
 392   end_of_stream_ = false;
 393   last_packet_timestamp_ = kNoTimestamp();
 394   last_packet_duration_ = kNoTimestamp();
 395 }
 396
 397 void FFmpegDemuxerStream::Stop() {
 398   DCHECK(task_runner_->BelongsToCurrentThread());
 399   buffer_queue_.Clear();
 400   if (!read_cb_.is_null()) {
 401     base::ResetAndReturn(&read_cb_).Run(
 402         DemuxerStream::kOk, DecoderBuffer::CreateEOSBuffer());
 403   }
 404   demuxer_ = NULL;
 405   stream_ = NULL;
 406   end_of_stream_ = true;
 407 }
 408
 409 DemuxerStream::Type FFmpegDemuxerStream::type() const {
 410   DCHECK(task_runner_->BelongsToCurrentThread());
 411   return type_;
 412 }
 413
 414 DemuxerStream::Liveness FFmpegDemuxerStream::liveness() const {
 415   DCHECK(task_runner_->BelongsToCurrentThread());
 416   return liveness_;
 417 }
 418
 419 void FFmpegDemuxerStream::Read(const ReadCB& read_cb) {
 420   DCHECK(task_runner_->BelongsToCurrentThread());
 421   CHECK(read_cb_.is_null()) << "Overlapping reads are not supported";
 422   read_cb_ = BindToCurrentLoop(read_cb);
 423
 424   // Don't accept any additional reads if we've been told to stop.
 425   // The |demuxer_| may have been destroyed in the pipeline thread.
 426   //
 427   // TODO(scherkus): it would be cleaner to reply with an error message.
 428   if (!demuxer_) {
 429     base::ResetAndReturn(&read_cb_).Run(
 430         DemuxerStream::kOk, DecoderBuffer::CreateEOSBuffer());
 431     return;
 432   }
 433
 434   SatisfyPendingRead();
 435 }
 436
 437 void FFmpegDemuxerStream::EnableBitstreamConverter() {
 438   DCHECK(task_runner_->BelongsToCurrentThread());
 439
 440 #if defined(USE_PROPRIETARY_CODECS)
 441   InitBitstreamConverter();
 442 #else
 443   NOTREACHED() << "Proprietary codecs not enabled.";
 444 #endif
 445 }
 446
 447 void FFmpegDemuxerStream::ResetBitstreamConverter() {
 448 #if defined(USE_PROPRIETARY_CODECS)
 449   if (bitstream_converter_)
 450     InitBitstreamConverter();
 451 #endif  // defined(USE_PROPRIETARY_CODECS)
 452 }
 453
 454 void FFmpegDemuxerStream::InitBitstreamConverter() {
 455 #if defined(USE_PROPRIETARY_CODECS)
 456   if (stream_->codec->codec_id == AV_CODEC_ID_H264) {
 457     bitstream_converter_.reset(
 458         new FFmpegH264ToAnnexBBitstreamConverter(stream_->codec));
 459   } else if (stream_->codec->codec_id == AV_CODEC_ID_AAC) {
 460     bitstream_converter_.reset(
 461         new FFmpegAACBitstreamConverter(stream_->codec));
 462   }
 463 #endif  // defined(USE_PROPRIETARY_CODECS)
 464 }
 465
 466 bool FFmpegDemuxerStream::SupportsConfigChanges() { return false; }
 467
 468 AudioDecoderConfig FFmpegDemuxerStream::audio_decoder_config() {
 469   DCHECK(task_runner_->BelongsToCurrentThread());
 470   CHECK_EQ(type_, AUDIO);
 471   return audio_config_;
 472 }
 473
 474 VideoDecoderConfig FFmpegDemuxerStream::video_decoder_config() {
 475   DCHECK(task_runner_->BelongsToCurrentThread());
 476   CHECK_EQ(type_, VIDEO);
 477   return video_config_;
 478 }
 479
 480 VideoRotation FFmpegDemuxerStream::video_rotation() {
 481   return video_rotation_;
 482 }
 483
 484 void FFmpegDemuxerStream::SetLiveness(Liveness liveness) {
 485   DCHECK(task_runner_->BelongsToCurrentThread());
 486   DCHECK_EQ(liveness_, LIVENESS_UNKNOWN);
 487   liveness_ = liveness;
 488 }
 489
 490 base::TimeDelta FFmpegDemuxerStream::GetElapsedTime() const {
 491   return ConvertStreamTimestamp(stream_->time_base, stream_->cur_dts);
 492 }
 493
 494 Ranges<base::TimeDelta> FFmpegDemuxerStream::GetBufferedRanges() const {
 495   return buffered_ranges_;
 496 }
 497
 498 void FFmpegDemuxerStream::SatisfyPendingRead() {
 499   DCHECK(task_runner_->BelongsToCurrentThread());
 500   if (!read_cb_.is_null()) {
 501     if (!buffer_queue_.IsEmpty()) {
 502       base::ResetAndReturn(&read_cb_).Run(
 503           DemuxerStream::kOk, buffer_queue_.Pop());
 504     } else if (end_of_stream_) {
 505       base::ResetAndReturn(&read_cb_).Run(
 506           DemuxerStream::kOk, DecoderBuffer::CreateEOSBuffer());
 507     }
 508   }
 509
 510   // Have capacity? Ask for more!
 511   if (HasAvailableCapacity() && !end_of_stream_) {
 512     demuxer_->NotifyCapacityAvailable();
 513   }
 514 }
 515
 516 bool FFmpegDemuxerStream::HasAvailableCapacity() {
 517   // TODO(scherkus): Remove this return and reenable time-based capacity
 518   // after our data sources support canceling/concurrent reads, see
 519   // http://crbug.com/165762 for details.
 520 #if 1
 521   return !read_cb_.is_null();
 522 #else
 523   // Try to have one second's worth of encoded data per stream.
 524   const base::TimeDelta kCapacity = base::TimeDelta::FromSeconds(1);
 525   return buffer_queue_.IsEmpty() || buffer_queue_.Duration() < kCapacity;
 526 #endif
 527 }
 528
 529 size_t FFmpegDemuxerStream::MemoryUsage() const {
 530   return buffer_queue_.data_size();
 531 }
 532
 533 TextKind FFmpegDemuxerStream::GetTextKind() const {
 534   DCHECK_EQ(type_, DemuxerStream::TEXT);
 535
 536   if (stream_->disposition & AV_DISPOSITION_CAPTIONS)
 537     return kTextCaptions;
 538
 539   if (stream_->disposition & AV_DISPOSITION_DESCRIPTIONS)
 540     return kTextDescriptions;
 541
 542   if (stream_->disposition & AV_DISPOSITION_METADATA)
 543     return kTextMetadata;
 544
 545   return kTextSubtitles;
 546 }
 547
 548 std::string FFmpegDemuxerStream::GetMetadata(const char* key) const {
 549   const AVDictionaryEntry* entry =
 550       av_dict_get(stream_->metadata, key, NULL, 0);
 551   return (entry == NULL || entry->value == NULL) ? "" : entry->value;
 552 }
 553
 554 // static
 555 base::TimeDelta FFmpegDemuxerStream::ConvertStreamTimestamp(
 556     const AVRational& time_base, int64 timestamp) {
 557   if (timestamp == static_cast<int64>(AV_NOPTS_VALUE))
 558     return kNoTimestamp();
 559
 560   return ConvertFromTimeBase(time_base, timestamp);
 561 }
 562
 563 //
 564 // FFmpegDemuxer
 565 //
 566 FFmpegDemuxer::FFmpegDemuxer(
 567     const scoped_refptr<base::SingleThreadTaskRunner>& task_runner,
 568     DataSource* data_source,
 569     const EncryptedMediaInitDataCB& encrypted_media_init_data_cb,
 570     const scoped_refptr<MediaLog>& media_log)
 571     : host_(NULL),
 572       task_runner_(task_runner),
 573       blocking_thread_("FFmpegDemuxer"),
 574       pending_read_(false),
 575       pending_seek_(false),
 576       data_source_(data_source),
 577       media_log_(media_log),
 578       bitrate_(0),
 579       start_time_(kNoTimestamp()),
 580       preferred_stream_for_seeking_(-1, kNoTimestamp()),
 581       fallback_stream_for_seeking_(-1, kNoTimestamp()),
 582       text_enabled_(false),
 583       duration_known_(false),
 584       encrypted_media_init_data_cb_(encrypted_media_init_data_cb),
 585       weak_factory_(this) {
 586   DCHECK(task_runner_.get());
 587   DCHECK(data_source_);
 588 }
 589
 590 FFmpegDemuxer::~FFmpegDemuxer() {}
 591
 592 void FFmpegDemuxer::Stop() {
 593   DCHECK(task_runner_->BelongsToCurrentThread());
 594
 595   // The order of Stop() and Abort() is important here.  If Abort() is called
 596   // first, control may pass into FFmpeg where it can destruct buffers that are
 597   // in the process of being fulfilled by the DataSource.
 598   data_source_->Stop();
 599   url_protocol_->Abort();
 600
 601   // This will block until all tasks complete. Note that after this returns it's
 602   // possible for reply tasks (e.g., OnReadFrameDone()) to be queued on this
 603   // thread. Each of the reply task methods must check whether we've stopped the
 604   // thread and drop their results on the floor.
 605   blocking_thread_.Stop();
 606
 607   StreamVector::iterator iter;
 608   for (iter = streams_.begin(); iter != streams_.end(); ++iter) {
 609     if (*iter)
 610       (*iter)->Stop();
 611   }
 612
 613   data_source_ = NULL;
 614 }
 615
 616 void FFmpegDemuxer::Seek(base::TimeDelta time, const PipelineStatusCB& cb) {
 617   DCHECK(task_runner_->BelongsToCurrentThread());
 618   CHECK(!pending_seek_);
 619
 620   // TODO(scherkus): Inspect |pending_read_| and cancel IO via |blocking_url_|,
 621   // otherwise we can end up waiting for a pre-seek read to complete even though
 622   // we know we're going to drop it on the floor.
 623
 624   // FFmpeg requires seeks to be adjusted according to the lowest starting time.
 625   // Since EnqueuePacket() rebased negative timestamps by the start time, we
 626   // must correct the shift here.
 627   //
 628   // Additionally, to workaround limitations in how we expose seekable ranges to
 629   // Blink (http://crbug.com/137275), we also want to clamp seeks before the
 630   // start time to the start time.
 631   const base::TimeDelta seek_time =
 632       start_time_ < base::TimeDelta() ? time + start_time_
 633                                       : time < start_time_ ? start_time_ : time;
 634
 635   // Choose the seeking stream based on whether it contains the seek time, if no
 636   // match can be found prefer the preferred stream.
 637   //
 638   // TODO(dalecurtis): Currently FFmpeg does not ensure that all streams in a
 639   // given container will demux all packets after the seek point.  Instead it
 640   // only guarantees that all packets after the file position of the seek will
 641   // be demuxed.  It's an open question whether FFmpeg should fix this:
 642   // http://lists.ffmpeg.org/pipermail/ffmpeg-devel/2014-June/159212.html
 643   // Tracked by http://crbug.com/387996.
 644   DCHECK(preferred_stream_for_seeking_.second != kNoTimestamp());
 645   const int stream_index =
 646       seek_time < preferred_stream_for_seeking_.second &&
 647               seek_time >= fallback_stream_for_seeking_.second
 648           ? fallback_stream_for_seeking_.first
 649           : preferred_stream_for_seeking_.first;
 650   DCHECK_NE(stream_index, -1);
 651
 652   const AVStream* seeking_stream =
 653       glue_->format_context()->streams[stream_index];
 654
 655   pending_seek_ = true;
 656   base::PostTaskAndReplyWithResult(
 657       blocking_thread_.task_runner().get(),
 658       FROM_HERE,
 659       base::Bind(&av_seek_frame,
 660                  glue_->format_context(),
 661                  seeking_stream->index,
 662                  ConvertToTimeBase(seeking_stream->time_base, seek_time),
 663                  // Always seek to a timestamp <= to the desired timestamp.
 664                  AVSEEK_FLAG_BACKWARD),
 665       base::Bind(
 666           &FFmpegDemuxer::OnSeekFrameDone, weak_factory_.GetWeakPtr(), cb));
 667 }
 668
 669 std::string FFmpegDemuxer::GetDisplayName() const {
 670   return "FFmpegDemuxer";
 671 }
 672
 673 void FFmpegDemuxer::Initialize(DemuxerHost* host,
 674                                const PipelineStatusCB& status_cb,
 675                                bool enable_text_tracks) {
 676   DCHECK(task_runner_->BelongsToCurrentThread());
 677   host_ = host;
 678   text_enabled_ = enable_text_tracks;
 679
 680   url_protocol_.reset(new BlockingUrlProtocol(data_source_, BindToCurrentLoop(
 681       base::Bind(&FFmpegDemuxer::OnDataSourceError, base::Unretained(this)))));
 682   glue_.reset(new FFmpegGlue(url_protocol_.get()));
 683   AVFormatContext* format_context = glue_->format_context();
 684
 685   // Disable ID3v1 tag reading to avoid costly seeks to end of file for data we
 686   // don't use.  FFmpeg will only read ID3v1 tags if no other metadata is
 687   // available, so add a metadata entry to ensure some is always present.
 688   av_dict_set(&format_context->metadata, "skip_id3v1_tags", "", 0);
 689
 690   // Ensure ffmpeg doesn't give up too early while looking for stream params;
 691   // this does not increase the amount of data downloaded.  The default value
 692   // is 5 AV_TIME_BASE units (1 second each), which prevents some oddly muxed
 693   // streams from being detected properly; this value was chosen arbitrarily.
 694   format_context->max_analyze_duration2 = 60 * AV_TIME_BASE;
 695
 696   // Open the AVFormatContext using our glue layer.
 697   CHECK(blocking_thread_.Start());
 698   base::PostTaskAndReplyWithResult(
 699       blocking_thread_.task_runner().get(),
 700       FROM_HERE,
 701       base::Bind(&FFmpegGlue::OpenContext, base::Unretained(glue_.get())),
 702       base::Bind(&FFmpegDemuxer::OnOpenContextDone,
 703                  weak_factory_.GetWeakPtr(),
 704                  status_cb));
 705 }
 706
 707 base::Time FFmpegDemuxer::GetTimelineOffset() const {
 708   return timeline_offset_;
 709 }
 710
 711 DemuxerStream* FFmpegDemuxer::GetStream(DemuxerStream::Type type) {
 712   DCHECK(task_runner_->BelongsToCurrentThread());
 713   return GetFFmpegStream(type);
 714 }
 715
 716 FFmpegDemuxerStream* FFmpegDemuxer::GetFFmpegStream(
 717     DemuxerStream::Type type) const {
 718   StreamVector::const_iterator iter;
 719   for (iter = streams_.begin(); iter != streams_.end(); ++iter) {
 720     if (*iter && (*iter)->type() == type) {
 721       return *iter;
 722     }
 723   }
 724   return NULL;
 725 }
 726
 727 base::TimeDelta FFmpegDemuxer::GetStartTime() const {
 728   return std::max(start_time_, base::TimeDelta());
 729 }
 730
 731 void FFmpegDemuxer::AddTextStreams() {
 732   DCHECK(task_runner_->BelongsToCurrentThread());
 733
 734   for (StreamVector::size_type idx = 0; idx < streams_.size(); ++idx) {
 735     FFmpegDemuxerStream* stream = streams_[idx];
 736     if (stream == NULL || stream->type() != DemuxerStream::TEXT)
 737       continue;
 738
 739     TextKind kind = stream->GetTextKind();
 740     std::string title = stream->GetMetadata("title");
 741     std::string language = stream->GetMetadata("language");
 742
 743     // TODO: Implement "id" metadata in FFMPEG.
 744     // See: http://crbug.com/323183
 745     host_->AddTextStream(stream, TextTrackConfig(kind, title, language,
 746         std::string()));
 747   }
 748 }
 749
 750 // Helper for calculating the bitrate of the media based on information stored
 751 // in |format_context| or failing that the size and duration of the media.
 752 //
 753 // Returns 0 if a bitrate could not be determined.
 754 static int CalculateBitrate(
 755     AVFormatContext* format_context,
 756     const base::TimeDelta& duration,
 757     int64 filesize_in_bytes) {
 758   // If there is a bitrate set on the container, use it.
 759   if (format_context->bit_rate > 0)
 760     return format_context->bit_rate;
 761
 762   // Then try to sum the bitrates individually per stream.
 763   int bitrate = 0;
 764   for (size_t i = 0; i < format_context->nb_streams; ++i) {
 765     AVCodecContext* codec_context = format_context->streams[i]->codec;
 766     bitrate += codec_context->bit_rate;
 767   }
 768   if (bitrate > 0)
 769     return bitrate;
 770
 771   // See if we can approximate the bitrate as long as we have a filesize and
 772   // valid duration.
 773   if (duration.InMicroseconds() <= 0 ||
 774       duration == kInfiniteDuration() ||
 775       filesize_in_bytes == 0) {
 776     return 0;
 777   }
 778
 779   // Do math in floating point as we'd overflow an int64 if the filesize was
 780   // larger than ~1073GB.
 781   double bytes = filesize_in_bytes;
 782   double duration_us = duration.InMicroseconds();
 783   return bytes * 8000000.0 / duration_us;
 784 }
 785
 786 void FFmpegDemuxer::OnOpenContextDone(const PipelineStatusCB& status_cb,
 787                                       bool result) {
 788   DCHECK(task_runner_->BelongsToCurrentThread());
 789   if (!blocking_thread_.IsRunning()) {
 790     MEDIA_LOG(ERROR, media_log_) << GetDisplayName() << ": bad state";
 791     status_cb.Run(PIPELINE_ERROR_ABORT);
 792     return;
 793   }
 794
 795   if (!result) {
 796     MEDIA_LOG(ERROR, media_log_) << GetDisplayName() << ": open context failed";
 797     status_cb.Run(DEMUXER_ERROR_COULD_NOT_OPEN);
 798     return;
 799   }
 800
 801   // Fully initialize AVFormatContext by parsing the stream a little.
 802   base::PostTaskAndReplyWithResult(
 803       blocking_thread_.task_runner().get(),
 804       FROM_HERE,
 805       base::Bind(&avformat_find_stream_info,
 806                  glue_->format_context(),
 807                  static_cast<AVDictionary**>(NULL)),
 808       base::Bind(&FFmpegDemuxer::OnFindStreamInfoDone,
 809                  weak_factory_.GetWeakPtr(),
 810                  status_cb));
 811 }
 812
 813 void FFmpegDemuxer::OnFindStreamInfoDone(const PipelineStatusCB& status_cb,
 814                                          int result) {
 815   DCHECK(task_runner_->BelongsToCurrentThread());
 816   if (!blocking_thread_.IsRunning() || !data_source_) {
 817     MEDIA_LOG(ERROR, media_log_) << GetDisplayName() << ": bad state";
 818     status_cb.Run(PIPELINE_ERROR_ABORT);
 819     return;
 820   }
 821
 822   if (result < 0) {
 823     MEDIA_LOG(ERROR, media_log_) << GetDisplayName()
 824                                  << ": find stream info failed";
 825     status_cb.Run(DEMUXER_ERROR_COULD_NOT_PARSE);
 826     return;
 827   }
 828
 829   // Create demuxer stream entries for each possible AVStream. Each stream
 830   // is examined to determine if it is supported or not (is the codec enabled
 831   // for it in this release?). Unsupported streams are skipped, allowing for
 832   // partial playback. At least one audio or video stream must be playable.
 833   AVFormatContext* format_context = glue_->format_context();
 834   streams_.resize(format_context->nb_streams);
 835
 836   // Estimate the start time for each stream by looking through the packets
 837   // buffered during avformat_find_stream_info().  These values will be
 838   // considered later when determining the actual stream start time.
 839   //
 840   // These packets haven't been completely processed yet, so only look through
 841   // these values if the AVFormatContext has a valid start time.
 842   //
 843   // If no estimate is found, the stream entry will be kInfiniteDuration().
 844   std::vector<base::TimeDelta> start_time_estimates(format_context->nb_streams,
 845                                                     kInfiniteDuration());
 846   const AVFormatInternal* internal = format_context->internal;
 847   if (internal && internal->packet_buffer &&
 848       format_context->start_time != static_cast<int64>(AV_NOPTS_VALUE)) {
 849     struct AVPacketList* packet_buffer = internal->packet_buffer;
 850     while (packet_buffer != internal->packet_buffer_end) {
 851       DCHECK_LT(static_cast<size_t>(packet_buffer->pkt.stream_index),
 852                 start_time_estimates.size());
 853       const AVStream* stream =
 854           format_context->streams[packet_buffer->pkt.stream_index];
 855       if (packet_buffer->pkt.pts != static_cast<int64>(AV_NOPTS_VALUE)) {
 856         const base::TimeDelta packet_pts =
 857             ConvertFromTimeBase(stream->time_base, packet_buffer->pkt.pts);
 858         if (packet_pts < start_time_estimates[stream->index])
 859           start_time_estimates[stream->index] = packet_pts;
 860       }
 861       packet_buffer = packet_buffer->next;
 862     }
 863   }
 864
 865   AVStream* audio_stream = NULL;
 866   AudioDecoderConfig audio_config;
 867
 868   AVStream* video_stream = NULL;
 869   VideoDecoderConfig video_config;
 870
 871   // If available, |start_time_| will be set to the lowest stream start time.
 872   start_time_ = kInfiniteDuration();
 873
 874   base::TimeDelta max_duration;
 875   for (size_t i = 0; i < format_context->nb_streams; ++i) {
 876     AVStream* stream = format_context->streams[i];
 877     const AVCodecContext* codec_context = stream->codec;
 878     const AVMediaType codec_type = codec_context->codec_type;
 879
 880     if (codec_type == AVMEDIA_TYPE_AUDIO) {
 881       if (audio_stream)
 882         continue;
 883
 884       // Log the codec detected, whether it is supported or not.
 885       UMA_HISTOGRAM_SPARSE_SLOWLY("Media.DetectedAudioCodec",
 886                                   codec_context->codec_id);
 887       // Ensure the codec is supported. IsValidConfig() also checks that the
 888       // channel layout and sample format are valid.
 889       AVStreamToAudioDecoderConfig(stream, &audio_config, false);
 890       if (!audio_config.IsValidConfig())
 891         continue;
 892       audio_stream = stream;
 893     } else if (codec_type == AVMEDIA_TYPE_VIDEO) {
 894       if (video_stream)
 895         continue;
 896
 897       // Log the codec detected, whether it is supported or not.
 898       UMA_HISTOGRAM_SPARSE_SLOWLY("Media.DetectedVideoCodec",
 899                                   codec_context->codec_id);
 900       // Ensure the codec is supported. IsValidConfig() also checks that the
 901       // frame size and visible size are valid.
 902       AVStreamToVideoDecoderConfig(stream, &video_config, false);
 903
 904       if (!video_config.IsValidConfig())
 905         continue;
 906       video_stream = stream;
 907     } else if (codec_type == AVMEDIA_TYPE_SUBTITLE) {
 908       if (codec_context->codec_id != AV_CODEC_ID_WEBVTT || !text_enabled_) {
 909         continue;
 910       }
 911     } else {
 912       continue;
 913     }
 914
 915     streams_[i] = new FFmpegDemuxerStream(this, stream);
 916     max_duration = std::max(max_duration, streams_[i]->duration());
 917
 918     const base::TimeDelta start_time =
 919         ExtractStartTime(stream, start_time_estimates[i]);
 920     const bool has_start_time = start_time != kNoTimestamp();
 921
 922     // Always prefer the video stream for seeking.  If none exists, we'll swap
 923     // the fallback stream with the preferred stream below.
 924     if (codec_type == AVMEDIA_TYPE_VIDEO) {
 925       preferred_stream_for_seeking_ =
 926           StreamSeekInfo(i, has_start_time ? start_time : base::TimeDelta());
 927     }
 928
 929     if (!has_start_time)
 930       continue;
 931
 932     if (start_time < start_time_) {
 933       start_time_ = start_time;
 934
 935       // Choose the stream with the lowest starting time as the fallback stream
 936       // for seeking.  Video should always be preferred.
 937       fallback_stream_for_seeking_ = StreamSeekInfo(i, start_time);
 938     }
 939   }
 940
 941   if (!audio_stream && !video_stream) {
 942     MEDIA_LOG(ERROR, media_log_) << GetDisplayName()
 943                                  << ": no supported streams";
 944     status_cb.Run(DEMUXER_ERROR_NO_SUPPORTED_STREAMS);
 945     return;
 946   }
 947
 948   if (text_enabled_)
 949     AddTextStreams();
 950
 951   if (format_context->duration != static_cast<int64_t>(AV_NOPTS_VALUE)) {
 952     // If there is a duration value in the container use that to find the
 953     // maximum between it and the duration from A/V streams.
 954     const AVRational av_time_base = {1, AV_TIME_BASE};
 955     max_duration =
 956         std::max(max_duration,
 957                  ConvertFromTimeBase(av_time_base, format_context->duration));
 958   } else {
 959     // The duration is unknown, in which case this is likely a live stream.
 960     max_duration = kInfiniteDuration();
 961   }
 962
 963   // Ogg has some peculiarities around negative timestamps, so use this flag to
 964   // setup the FFmpegDemuxerStreams appropriately.
 965   //
 966   // Post-decode frame dropping for packets with negative timestamps is outlined
 967   // in section A.2 in the Ogg Vorbis spec:
 968   // http://xiph.org/vorbis/doc/Vorbis_I_spec.html
 969   if (strcmp(format_context->iformat->name, "ogg") == 0 && audio_stream &&
 970       audio_stream->codec->codec_id == AV_CODEC_ID_VORBIS) {
 971     for (size_t i = 0; i < streams_.size(); ++i) {
 972       if (streams_[i])
 973         streams_[i]->enable_negative_timestamp_fixups_for_ogg();
 974     }
 975
 976     // Fixup the seeking information to avoid selecting the audio stream simply
 977     // because it has a lower starting time.
 978     if (fallback_stream_for_seeking_.first == audio_stream->index &&
 979         fallback_stream_for_seeking_.second < base::TimeDelta()) {
 980       fallback_stream_for_seeking_.second = base::TimeDelta();
 981     }
 982   }
 983
 984   // If no start time could be determined, default to zero and prefer the video
 985   // stream over the audio stream for seeking.  E.g., The WAV demuxer does not
 986   // put timestamps on its frames.
 987   if (start_time_ == kInfiniteDuration()) {
 988     start_time_ = base::TimeDelta();
 989     preferred_stream_for_seeking_ = StreamSeekInfo(
 990         video_stream ? video_stream->index : audio_stream->index, start_time_);
 991   } else if (!video_stream) {
 992     // If no video stream exists, use the audio or text stream found above.
 993     preferred_stream_for_seeking_ = fallback_stream_for_seeking_;
 994   }
 995
 996   // MPEG-4 B-frames cause grief for a simple container like AVI. Enable PTS
 997   // generation so we always get timestamps, see http://crbug.com/169570
 998   if (strcmp(format_context->iformat->name, "avi") == 0)
 999     format_context->flags |= AVFMT_FLAG_GENPTS;
1000
1001   // For testing purposes, don't overwrite the timeline offset if set already.
1002   if (timeline_offset_.is_null())
1003     timeline_offset_ = ExtractTimelineOffset(format_context);
1004
1005   // Since we're shifting the externally visible start time to zero, we need to
1006   // adjust the timeline offset to compensate.
1007   if (!timeline_offset_.is_null() && start_time_ < base::TimeDelta())
1008     timeline_offset_ += start_time_;
1009
1010   if (max_duration == kInfiniteDuration() && !timeline_offset_.is_null()) {
1011     SetLiveness(DemuxerStream::LIVENESS_LIVE);
1012   } else if (max_duration != kInfiniteDuration()) {
1013     SetLiveness(DemuxerStream::LIVENESS_RECORDED);
1014   } else {
1015     SetLiveness(DemuxerStream::LIVENESS_UNKNOWN);
1016   }
1017
1018   // Good to go: set the duration and bitrate and notify we're done
1019   // initializing.
1020   host_->SetDuration(max_duration);
1021   duration_known_ = (max_duration != kInfiniteDuration());
1022
1023   int64 filesize_in_bytes = 0;
1024   url_protocol_->GetSize(&filesize_in_bytes);
1025   bitrate_ = CalculateBitrate(format_context, max_duration, filesize_in_bytes);
1026   if (bitrate_ > 0)
1027     data_source_->SetBitrate(bitrate_);
1028
1029   // Audio logging
1030   if (audio_stream) {
1031     AVCodecContext* audio_codec = audio_stream->codec;
1032     media_log_->SetBooleanProperty("found_audio_stream", true);
1033
1034     SampleFormat sample_format = audio_config.sample_format();
1035     std::string sample_name = SampleFormatToString(sample_format);
1036
1037     media_log_->SetStringProperty("audio_sample_format", sample_name);
1038
1039     AVCodec* codec = avcodec_find_decoder(audio_codec->codec_id);
1040     if (codec) {
1041       media_log_->SetStringProperty("audio_codec_name", codec->name);
1042     }
1043
1044     media_log_->SetIntegerProperty("audio_channels_count",
1045                                    audio_codec->channels);
1046     media_log_->SetIntegerProperty("audio_samples_per_second",
1047                                    audio_config.samples_per_second());
1048   } else {
1049     media_log_->SetBooleanProperty("found_audio_stream", false);
1050   }
1051
1052   // Video logging
1053   if (video_stream) {
1054     AVCodecContext* video_codec = video_stream->codec;
1055     media_log_->SetBooleanProperty("found_video_stream", true);
1056
1057     AVCodec* codec = avcodec_find_decoder(video_codec->codec_id);
1058     if (codec) {
1059       media_log_->SetStringProperty("video_codec_name", codec->name);
1060     } else if (video_codec->codec_id == AV_CODEC_ID_VP9) {
1061       // ffmpeg doesn't know about VP9 decoder. So we need to log it explicitly.
1062       media_log_->SetStringProperty("video_codec_name", "vp9");
1063     }
1064
1065     media_log_->SetIntegerProperty("width", video_codec->width);
1066     media_log_->SetIntegerProperty("height", video_codec->height);
1067     media_log_->SetIntegerProperty("coded_width",
1068                                    video_codec->coded_width);
1069     media_log_->SetIntegerProperty("coded_height",
1070                                    video_codec->coded_height);
1071     media_log_->SetStringProperty(
1072         "time_base",
1073         base::StringPrintf("%d/%d",
1074                            video_codec->time_base.num,
1075                            video_codec->time_base.den));
1076     media_log_->SetStringProperty(
1077         "video_format", VideoPixelFormatToString(video_config.format()));
1078     media_log_->SetBooleanProperty("video_is_encrypted",
1079                                    video_config.is_encrypted());
1080   } else {
1081     media_log_->SetBooleanProperty("found_video_stream", false);
1082   }
1083
1084   media_log_->SetTimeProperty("max_duration", max_duration);
1085   media_log_->SetTimeProperty("start_time", start_time_);
1086   media_log_->SetIntegerProperty("bitrate", bitrate_);
1087
1088   status_cb.Run(PIPELINE_OK);
1089 }
1090
1091 void FFmpegDemuxer::OnSeekFrameDone(const PipelineStatusCB& cb, int result) {
1092   DCHECK(task_runner_->BelongsToCurrentThread());
1093   CHECK(pending_seek_);
1094   pending_seek_ = false;
1095
1096   if (!blocking_thread_.IsRunning()) {
1097     MEDIA_LOG(ERROR, media_log_) << GetDisplayName() << ": bad state";
1098     cb.Run(PIPELINE_ERROR_ABORT);
1099     return;
1100   }
1101
1102   if (result < 0) {
1103     // Use VLOG(1) instead of NOTIMPLEMENTED() to prevent the message being
1104     // captured from stdout and contaminates testing.
1105     // TODO(scherkus): Implement this properly and signal error (BUG=23447).
1106     VLOG(1) << "Not implemented";
1107   }
1108
1109   // Tell streams to flush buffers due to seeking.
1110   StreamVector::iterator iter;
1111   for (iter = streams_.begin(); iter != streams_.end(); ++iter) {
1112     if (*iter)
1113       (*iter)->FlushBuffers();
1114   }
1115
1116   // Resume reading until capacity.
1117   ReadFrameIfNeeded();
1118
1119   // Notify we're finished seeking.
1120   cb.Run(PIPELINE_OK);
1121 }
1122
1123 void FFmpegDemuxer::ReadFrameIfNeeded() {
1124   DCHECK(task_runner_->BelongsToCurrentThread());
1125
1126   // Make sure we have work to do before reading.
1127   if (!blocking_thread_.IsRunning() || !StreamsHaveAvailableCapacity() ||
1128       pending_read_ || pending_seek_) {
1129     return;
1130   }
1131
1132   // Allocate and read an AVPacket from the media. Save |packet_ptr| since
1133   // evaluation order of packet.get() and base::Passed(&packet) is
1134   // undefined.
1135   ScopedAVPacket packet(new AVPacket());
1136   AVPacket* packet_ptr = packet.get();
1137
1138   pending_read_ = true;
1139   base::PostTaskAndReplyWithResult(
1140       blocking_thread_.task_runner().get(),
1141       FROM_HERE,
1142       base::Bind(&av_read_frame, glue_->format_context(), packet_ptr),
1143       base::Bind(&FFmpegDemuxer::OnReadFrameDone,
1144                  weak_factory_.GetWeakPtr(),
1145                  base::Passed(&packet)));
1146 }
1147
1148 void FFmpegDemuxer::OnReadFrameDone(ScopedAVPacket packet, int result) {
1149   DCHECK(task_runner_->BelongsToCurrentThread());
1150   DCHECK(pending_read_);
1151   pending_read_ = false;
1152
1153   if (!blocking_thread_.IsRunning() || pending_seek_) {
1154     return;
1155   }
1156
1157   // Consider the stream as ended if:
1158   // - either underlying ffmpeg returned an error
1159   // - or FFMpegDemuxer reached the maximum allowed memory usage.
1160   if (result < 0 || IsMaxMemoryUsageReached()) {
1161     // Update the duration based on the highest elapsed time across all streams
1162     // if it was previously unknown.
1163     if (!duration_known_) {
1164       base::TimeDelta max_duration;
1165
1166       for (StreamVector::iterator iter = streams_.begin();
1167            iter != streams_.end();
1168            ++iter) {
1169         if (!*iter)
1170           continue;
1171
1172         base::TimeDelta duration = (*iter)->GetElapsedTime();
1173         if (duration != kNoTimestamp() && duration > max_duration)
1174           max_duration = duration;
1175       }
1176
1177       if (max_duration > base::TimeDelta()) {
1178         host_->SetDuration(max_duration);
1179         duration_known_ = true;
1180       }
1181     }
1182     // If we have reached the end of stream, tell the downstream filters about
1183     // the event.
1184     StreamHasEnded();
1185     return;
1186   }
1187
1188   // Queue the packet with the appropriate stream.
1189   DCHECK_GE(packet->stream_index, 0);
1190   DCHECK_LT(packet->stream_index, static_cast<int>(streams_.size()));
1191
1192   // Defend against ffmpeg giving us a bad stream index.
1193   if (packet->stream_index >= 0 &&
1194       packet->stream_index < static_cast<int>(streams_.size()) &&
1195       streams_[packet->stream_index]) {
1196     // TODO(scherkus): Fix demuxing upstream to never return packets w/o data
1197     // when av_read_frame() returns success code. See bug comment for ideas:
1198     //
1199     // https://code.google.com/p/chromium/issues/detail?id=169133#c10
1200     if (!packet->data) {
1201       ScopedAVPacket new_packet(new AVPacket());
1202       av_new_packet(new_packet.get(), 0);
1203       av_packet_copy_props(new_packet.get(), packet.get());
1204       packet.swap(new_packet);
1205     }
1206
1207     // Special case for opus in ogg.  FFmpeg is pre-trimming the codec delay
1208     // from the packet timestamp.  Chrome expects to handle this itself inside
1209     // the decoder, so shift timestamps by the delay in this case.
1210     // TODO(dalecurtis): Try to get fixed upstream.  See http://crbug.com/328207
1211     if (strcmp(glue_->format_context()->iformat->name, "ogg") == 0) {
1212       const AVCodecContext* codec_context =
1213           glue_->format_context()->streams[packet->stream_index]->codec;
1214       if (codec_context->codec_id == AV_CODEC_ID_OPUS &&
1215           codec_context->delay > 0) {
1216         packet->pts += codec_context->delay;
1217       }
1218     }
1219
1220     FFmpegDemuxerStream* demuxer_stream = streams_[packet->stream_index];
1221     demuxer_stream->EnqueuePacket(packet.Pass());
1222   }
1223
1224   // Keep reading until we've reached capacity.
1225   ReadFrameIfNeeded();
1226 }
1227
1228 bool FFmpegDemuxer::StreamsHaveAvailableCapacity() {
1229   DCHECK(task_runner_->BelongsToCurrentThread());
1230   StreamVector::iterator iter;
1231   for (iter = streams_.begin(); iter != streams_.end(); ++iter) {
1232     if (*iter && (*iter)->HasAvailableCapacity()) {
1233       return true;
1234     }
1235   }
1236   return false;
1237 }
1238
1239 bool FFmpegDemuxer::IsMaxMemoryUsageReached() const {
1240   DCHECK(task_runner_->BelongsToCurrentThread());
1241
1242   // Max allowed memory usage, all streams combined.
1243   const size_t kDemuxerMemoryLimit = 150 * 1024 * 1024;
1244
1245   size_t memory_left = kDemuxerMemoryLimit;
1246   for (StreamVector::const_iterator iter = streams_.begin();
1247        iter != streams_.end(); ++iter) {
1248     if (!(*iter))
1249       continue;
1250
1251     size_t stream_memory_usage = (*iter)->MemoryUsage();
1252     if (stream_memory_usage > memory_left)
1253       return true;
1254     memory_left -= stream_memory_usage;
1255   }
1256   return false;
1257 }
1258
1259 void FFmpegDemuxer::StreamHasEnded() {
1260   DCHECK(task_runner_->BelongsToCurrentThread());
1261   StreamVector::iterator iter;
1262   for (iter = streams_.begin(); iter != streams_.end(); ++iter) {
1263     if (!*iter)
1264       continue;
1265     (*iter)->SetEndOfStream();
1266   }
1267 }
1268
1269 void FFmpegDemuxer::OnEncryptedMediaInitData(
1270     EmeInitDataType init_data_type,
1271     const std::string& encryption_key_id) {
1272   std::vector<uint8> key_id_local(encryption_key_id.begin(),
1273                                   encryption_key_id.end());
1274   encrypted_media_init_data_cb_.Run(init_data_type, key_id_local);
1275 }
1276
1277 void FFmpegDemuxer::NotifyCapacityAvailable() {
1278   DCHECK(task_runner_->BelongsToCurrentThread());
1279   ReadFrameIfNeeded();
1280 }
1281
1282 void FFmpegDemuxer::NotifyBufferingChanged() {
1283   DCHECK(task_runner_->BelongsToCurrentThread());
1284   Ranges<base::TimeDelta> buffered;
1285   FFmpegDemuxerStream* audio = GetFFmpegStream(DemuxerStream::AUDIO);
1286   FFmpegDemuxerStream* video = GetFFmpegStream(DemuxerStream::VIDEO);
1287   if (audio && video) {
1288     buffered = audio->GetBufferedRanges().IntersectionWith(
1289         video->GetBufferedRanges());
1290   } else if (audio) {
1291     buffered = audio->GetBufferedRanges();
1292   } else if (video) {
1293     buffered = video->GetBufferedRanges();
1294   }
1295   for (size_t i = 0; i < buffered.size(); ++i)
1296     host_->AddBufferedTimeRange(buffered.start(i), buffered.end(i));
1297 }
1298
1299 void FFmpegDemuxer::OnDataSourceError() {
1300   MEDIA_LOG(ERROR, media_log_) << GetDisplayName() << ": data source error";
1301   host_->OnDemuxerError(PIPELINE_ERROR_READ);
1302 }
1303
1304 void FFmpegDemuxer::SetLiveness(DemuxerStream::Liveness liveness) {
1305   DCHECK(task_runner_->BelongsToCurrentThread());
1306   for (const auto& stream : streams_) {  // |stream| is a ref to a pointer.
1307     if (stream)
1308       stream->SetLiveness(liveness);
1309   }
1310 }
1311
1312 }  // namespace media