media/formats/mp4/mp4_stream

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This source file includes following definitions.
is_video_track_encrypted_
Init
Reset
Flush
ParseBox
ParseMoov
ParseMoof
EmitNeedKeyIfNecessary
PrepareAVCBuffer
PrepareAACBuffer
EnqueueSample
SendAndFlushSamples
ReadAndDiscardMDATsUntil
ChangeState
// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "media/formats/mp4/mp4_stream_parser.h"

#include "base/callback.h"
#include "base/callback_helpers.h"
#include "base/logging.h"
#include "base/time/time.h"
#include "media/base/audio_decoder_config.h"
#include "media/base/stream_parser_buffer.h"
#include "media/base/text_track_config.h"
#include "media/base/video_decoder_config.h"
#include "media/base/video_util.h"
#include "media/formats/mp4/box_definitions.h"
#include "media/formats/mp4/box_reader.h"
#include "media/formats/mp4/es_descriptor.h"
#include "media/formats/mp4/rcheck.h"
#include "media/formats/mpeg/adts_constants.h"

namespace media {
namespace mp4 {

// TODO(xhwang): Figure out the init data type appropriately once it's spec'ed.
static const char kMp4InitDataType[] = "video/mp4";

MP4StreamParser::MP4StreamParser(const std::set<int>& audio_object_types,
                                 bool has_sbr)
    : state_(kWaitingForInit),
      moof_head_(0),
      mdat_tail_(0),
      has_audio_(false),
      has_video_(false),
      audio_track_id_(0),
      video_track_id_(0),
      audio_object_types_(audio_object_types),
      has_sbr_(has_sbr),
      is_audio_track_encrypted_(false),
      is_video_track_encrypted_(false) {
}

MP4StreamParser::~MP4StreamParser() {}

void MP4StreamParser::Init(const InitCB& init_cb,
                           const NewConfigCB& config_cb,
                           const NewBuffersCB& new_buffers_cb,
                           bool /* ignore_text_tracks */ ,
                           const NeedKeyCB& need_key_cb,
                           const NewMediaSegmentCB& new_segment_cb,
                           const base::Closure& end_of_segment_cb,
                           const LogCB& log_cb) {
  DCHECK_EQ(state_, kWaitingForInit);
  DCHECK(init_cb_.is_null());
  DCHECK(!init_cb.is_null());
  DCHECK(!config_cb.is_null());
  DCHECK(!new_buffers_cb.is_null());
  DCHECK(!need_key_cb.is_null());
  DCHECK(!end_of_segment_cb.is_null());

  ChangeState(kParsingBoxes);
  init_cb_ = init_cb;
  config_cb_ = config_cb;
  new_buffers_cb_ = new_buffers_cb;
  need_key_cb_ = need_key_cb;
  new_segment_cb_ = new_segment_cb;
  end_of_segment_cb_ = end_of_segment_cb;
  log_cb_ = log_cb;
}

void MP4StreamParser::Reset() {
  queue_.Reset();
  runs_.reset();
  moof_head_ = 0;
  mdat_tail_ = 0;
}

void MP4StreamParser::Flush() {
  DCHECK_NE(state_, kWaitingForInit);
  Reset();
  ChangeState(kParsingBoxes);
}

bool MP4StreamParser::Parse(const uint8* buf, int size) {
  DCHECK_NE(state_, kWaitingForInit);

  if (state_ == kError)
    return false;

  queue_.Push(buf, size);

  BufferQueue audio_buffers;
  BufferQueue video_buffers;

  bool result, err = false;

  do {
    if (state_ == kParsingBoxes) {
      result = ParseBox(&err);
    } else {
      DCHECK_EQ(kEmittingSamples, state_);
      result = EnqueueSample(&audio_buffers, &video_buffers, &err);
      if (result) {
        int64 max_clear = runs_->GetMaxClearOffset() + moof_head_;
        err = !ReadAndDiscardMDATsUntil(max_clear);
      }
    }
  } while (result && !err);

  if (!err)
    err = !SendAndFlushSamples(&audio_buffers, &video_buffers);

  if (err) {
    DLOG(ERROR) << "Error while parsing MP4";
    moov_.reset();
    Reset();
    ChangeState(kError);
    return false;
  }

  return true;
}

bool MP4StreamParser::ParseBox(bool* err) {
  const uint8* buf;
  int size;
  queue_.Peek(&buf, &size);
  if (!size) return false;

  scoped_ptr<BoxReader> reader(
      BoxReader::ReadTopLevelBox(buf, size, log_cb_, err));
  if (reader.get() == NULL) return false;

  if (reader->type() == FOURCC_MOOV) {
    *err = !ParseMoov(reader.get());
  } else if (reader->type() == FOURCC_MOOF) {
    moof_head_ = queue_.head();
    *err = !ParseMoof(reader.get());

    // Set up first mdat offset for ReadMDATsUntil().
    mdat_tail_ = queue_.head() + reader->size();

    // Return early to avoid evicting 'moof' data from queue. Auxiliary info may
    // be located anywhere in the file, including inside the 'moof' itself.
    // (Since 'default-base-is-moof' is mandated, no data references can come
    // before the head of the 'moof', so keeping this box around is sufficient.)
    return !(*err);
  } else {
    MEDIA_LOG(log_cb_) << "Skipping unrecognized top-level box: "
                       << FourCCToString(reader->type());
  }

  queue_.Pop(reader->size());
  return !(*err);
}


bool MP4StreamParser::ParseMoov(BoxReader* reader) {
  moov_.reset(new Movie);
  RCHECK(moov_->Parse(reader));
  runs_.reset();

  has_audio_ = false;
  has_video_ = false;

  AudioDecoderConfig audio_config;
  VideoDecoderConfig video_config;

  for (std::vector<Track>::const_iterator track = moov_->tracks.begin();
       track != moov_->tracks.end(); ++track) {
    // TODO(strobe): Only the first audio and video track present in a file are
    // used. (Track selection is better accomplished via Source IDs, though, so
    // adding support for track selection within a stream is low-priority.)
    const SampleDescription& samp_descr =
        track->media.information.sample_table.description;

    // TODO(strobe): When codec reconfigurations are supported, detect and send
    // a codec reconfiguration for fragments using a sample description index
    // different from the previous one
    size_t desc_idx = 0;
    for (size_t t = 0; t < moov_->extends.tracks.size(); t++) {
      const TrackExtends& trex = moov_->extends.tracks[t];
      if (trex.track_id == track->header.track_id) {
        desc_idx = trex.default_sample_description_index;
        break;
      }
    }
    RCHECK(desc_idx > 0);
    desc_idx -= 1;  // BMFF descriptor index is one-based

    if (track->media.handler.type == kAudio && !audio_config.IsValidConfig()) {
      RCHECK(!samp_descr.audio_entries.empty());

      // It is not uncommon to find otherwise-valid files with incorrect sample
      // description indices, so we fail gracefully in that case.
      if (desc_idx >= samp_descr.audio_entries.size())
        desc_idx = 0;
      const AudioSampleEntry& entry = samp_descr.audio_entries[desc_idx];
      const AAC& aac = entry.esds.aac;

      if (!(entry.format == FOURCC_MP4A ||
            (entry.format == FOURCC_ENCA &&
             entry.sinf.format.format == FOURCC_MP4A))) {
        MEDIA_LOG(log_cb_) << "Unsupported audio format 0x"
                           << std::hex << entry.format << " in stsd box.";
        return false;
      }

      uint8 audio_type = entry.esds.object_type;
      DVLOG(1) << "audio_type " << std::hex << audio_type;
      if (audio_object_types_.find(audio_type) == audio_object_types_.end()) {
        MEDIA_LOG(log_cb_) << "audio object type 0x" << std::hex << audio_type
                           << " does not match what is specified in the"
                           << " mimetype.";
        return false;
      }

      AudioCodec codec = kUnknownAudioCodec;
      ChannelLayout channel_layout = CHANNEL_LAYOUT_NONE;
      int sample_per_second = 0;
      std::vector<uint8> extra_data;
      // Check if it is MPEG4 AAC defined in ISO 14496 Part 3 or
      // supported MPEG2 AAC varients.
      if (ESDescriptor::IsAAC(audio_type)) {
        codec = kCodecAAC;
        channel_layout = aac.GetChannelLayout(has_sbr_);
        sample_per_second = aac.GetOutputSamplesPerSecond(has_sbr_);
#if defined(OS_ANDROID)
        extra_data = aac.codec_specific_data();
#endif
      } else {
        MEDIA_LOG(log_cb_) << "Unsupported audio object type 0x" << std::hex
                           << audio_type << " in esds.";
        return false;
      }

      SampleFormat sample_format;
      if (entry.samplesize == 8) {
        sample_format = kSampleFormatU8;
      } else if (entry.samplesize == 16) {
        sample_format = kSampleFormatS16;
      } else if (entry.samplesize == 32) {
        sample_format = kSampleFormatS32;
      } else {
        LOG(ERROR) << "Unsupported sample size.";
        return false;
      }

      is_audio_track_encrypted_ = entry.sinf.info.track_encryption.is_encrypted;
      DVLOG(1) << "is_audio_track_encrypted_: " << is_audio_track_encrypted_;
      audio_config.Initialize(
          codec, sample_format, channel_layout, sample_per_second,
          extra_data.size() ? &extra_data[0] : NULL, extra_data.size(),
          is_audio_track_encrypted_, false, base::TimeDelta(),
          base::TimeDelta());
      has_audio_ = true;
      audio_track_id_ = track->header.track_id;
    }
    if (track->media.handler.type == kVideo && !video_config.IsValidConfig()) {
      RCHECK(!samp_descr.video_entries.empty());
      if (desc_idx >= samp_descr.video_entries.size())
        desc_idx = 0;
      const VideoSampleEntry& entry = samp_descr.video_entries[desc_idx];

      if (!entry.IsFormatValid()) {
        MEDIA_LOG(log_cb_) << "Unsupported video format 0x"
                           << std::hex << entry.format << " in stsd box.";
        return false;
      }

      // TODO(strobe): Recover correct crop box
      gfx::Size coded_size(entry.width, entry.height);
      gfx::Rect visible_rect(coded_size);
      gfx::Size natural_size = GetNaturalSize(visible_rect.size(),
                                              entry.pixel_aspect.h_spacing,
                                              entry.pixel_aspect.v_spacing);
      is_video_track_encrypted_ = entry.sinf.info.track_encryption.is_encrypted;
      DVLOG(1) << "is_video_track_encrypted_: " << is_video_track_encrypted_;
      video_config.Initialize(kCodecH264, H264PROFILE_MAIN,  VideoFrame::YV12,
                              coded_size, visible_rect, natural_size,
                              // No decoder-specific buffer needed for AVC;
                              // SPS/PPS are embedded in the video stream
                              NULL, 0, is_video_track_encrypted_, false);
      has_video_ = true;
      video_track_id_ = track->header.track_id;
    }
  }

  RCHECK(config_cb_.Run(audio_config, video_config, TextTrackConfigMap()));

  base::TimeDelta duration;
  if (moov_->extends.header.fragment_duration > 0) {
    duration = TimeDeltaFromRational(moov_->extends.header.fragment_duration,
                                     moov_->header.timescale);
  } else if (moov_->header.duration > 0 &&
             moov_->header.duration != kuint64max) {
    duration = TimeDeltaFromRational(moov_->header.duration,
                                     moov_->header.timescale);
  } else {
    duration = kInfiniteDuration();
  }

  if (!init_cb_.is_null())
    base::ResetAndReturn(&init_cb_).Run(true, duration, false);

  EmitNeedKeyIfNecessary(moov_->pssh);
  return true;
}

bool MP4StreamParser::ParseMoof(BoxReader* reader) {
  RCHECK(moov_.get());  // Must already have initialization segment
  MovieFragment moof;
  RCHECK(moof.Parse(reader));
  if (!runs_)
    runs_.reset(new TrackRunIterator(moov_.get(), log_cb_));
  RCHECK(runs_->Init(moof));
  EmitNeedKeyIfNecessary(moof.pssh);
  new_segment_cb_.Run();
  ChangeState(kEmittingSamples);
  return true;
}

void MP4StreamParser::EmitNeedKeyIfNecessary(
    const std::vector<ProtectionSystemSpecificHeader>& headers) {
  // TODO(strobe): ensure that the value of init_data (all PSSH headers
  // concatenated in arbitrary order) matches the EME spec.
  // See https://www.w3.org/Bugs/Public/show_bug.cgi?id=17673.
  if (headers.empty())
    return;

  size_t total_size = 0;
  for (size_t i = 0; i < headers.size(); i++)
    total_size += headers[i].raw_box.size();

  std::vector<uint8> init_data(total_size);
  size_t pos = 0;
  for (size_t i = 0; i < headers.size(); i++) {
    memcpy(&init_data[pos], &headers[i].raw_box[0],
           headers[i].raw_box.size());
    pos += headers[i].raw_box.size();
  }
  need_key_cb_.Run(kMp4InitDataType, init_data);
}

bool MP4StreamParser::PrepareAVCBuffer(
    const AVCDecoderConfigurationRecord& avc_config,
    std::vector<uint8>* frame_buf,
    std::vector<SubsampleEntry>* subsamples) const {
  // Convert the AVC NALU length fields to Annex B headers, as expected by
  // decoding libraries. Since this may enlarge the size of the buffer, we also
  // update the clear byte count for each subsample if encryption is used to
  // account for the difference in size between the length prefix and Annex B
  // start code.
  RCHECK(AVC::ConvertFrameToAnnexB(avc_config.length_size, frame_buf));
  if (!subsamples->empty()) {
    const int nalu_size_diff = 4 - avc_config.length_size;
    size_t expected_size = runs_->sample_size() +
        subsamples->size() * nalu_size_diff;
    RCHECK(frame_buf->size() == expected_size);
    for (size_t i = 0; i < subsamples->size(); i++)
      (*subsamples)[i].clear_bytes += nalu_size_diff;
  }

  if (runs_->is_keyframe()) {
    // If this is a keyframe, we (re-)inject SPS and PPS headers at the start of
    // a frame. If subsample info is present, we also update the clear byte
    // count for that first subsample.
    std::vector<uint8> param_sets;
    RCHECK(AVC::ConvertConfigToAnnexB(avc_config, &param_sets));
    frame_buf->insert(frame_buf->begin(),
                      param_sets.begin(), param_sets.end());
    if (!subsamples->empty())
      (*subsamples)[0].clear_bytes += param_sets.size();
  }
  return true;
}

bool MP4StreamParser::PrepareAACBuffer(
    const AAC& aac_config, std::vector<uint8>* frame_buf,
    std::vector<SubsampleEntry>* subsamples) const {
  // Append an ADTS header to every audio sample.
  RCHECK(aac_config.ConvertEsdsToADTS(frame_buf));

  // As above, adjust subsample information to account for the headers. AAC is
  // not required to use subsample encryption, so we may need to add an entry.
  if (subsamples->empty()) {
    SubsampleEntry entry;
    entry.clear_bytes = kADTSHeaderMinSize;
    entry.cypher_bytes = frame_buf->size() - kADTSHeaderMinSize;
    subsamples->push_back(entry);
  } else {
    (*subsamples)[0].clear_bytes += kADTSHeaderMinSize;
  }
  return true;
}

bool MP4StreamParser::EnqueueSample(BufferQueue* audio_buffers,
                                    BufferQueue* video_buffers,
                                    bool* err) {
  if (!runs_->IsRunValid()) {
    // Flush any buffers we've gotten in this chunk so that buffers don't
    // cross NewSegment() calls
    *err = !SendAndFlushSamples(audio_buffers, video_buffers);
    if (*err)
      return false;

    // Remain in kEnqueueingSamples state, discarding data, until the end of
    // the current 'mdat' box has been appended to the queue.
    if (!queue_.Trim(mdat_tail_))
      return false;

    ChangeState(kParsingBoxes);
    end_of_segment_cb_.Run();
    return true;
  }

  if (!runs_->IsSampleValid()) {
    runs_->AdvanceRun();
    return true;
  }

  DCHECK(!(*err));

  const uint8* buf;
  int buf_size;
  queue_.Peek(&buf, &buf_size);
  if (!buf_size) return false;

  bool audio = has_audio_ && audio_track_id_ == runs_->track_id();
  bool video = has_video_ && video_track_id_ == runs_->track_id();

  // Skip this entire track if it's not one we're interested in
  if (!audio && !video)
    runs_->AdvanceRun();

  // Attempt to cache the auxiliary information first. Aux info is usually
  // placed in a contiguous block before the sample data, rather than being
  // interleaved. If we didn't cache it, this would require that we retain the
  // start of the segment buffer while reading samples. Aux info is typically
  // quite small compared to sample data, so this pattern is useful on
  // memory-constrained devices where the source buffer consumes a substantial
  // portion of the total system memory.
  if (runs_->AuxInfoNeedsToBeCached()) {
    queue_.PeekAt(runs_->aux_info_offset() + moof_head_, &buf, &buf_size);
    if (buf_size < runs_->aux_info_size()) return false;
    *err = !runs_->CacheAuxInfo(buf, buf_size);
    return !*err;
  }

  queue_.PeekAt(runs_->sample_offset() + moof_head_, &buf, &buf_size);
  if (buf_size < runs_->sample_size()) return false;

  scoped_ptr<DecryptConfig> decrypt_config;
  std::vector<SubsampleEntry> subsamples;
  if (runs_->is_encrypted()) {
    decrypt_config = runs_->GetDecryptConfig();
    if (!decrypt_config) {
      *err = true;
      return false;
    }
    subsamples = decrypt_config->subsamples();
  }

  std::vector<uint8> frame_buf(buf, buf + runs_->sample_size());
  if (video) {
    if (!PrepareAVCBuffer(runs_->video_description().avcc,
                          &frame_buf, &subsamples)) {
      MEDIA_LOG(log_cb_) << "Failed to prepare AVC sample for decode";
      *err = true;
      return false;
    }
  }

  if (audio) {
    if (ESDescriptor::IsAAC(runs_->audio_description().esds.object_type) &&
        !PrepareAACBuffer(runs_->audio_description().esds.aac,
                          &frame_buf, &subsamples)) {
      MEDIA_LOG(log_cb_) << "Failed to prepare AAC sample for decode";
      *err = true;
      return false;
    }
  }

  if (decrypt_config) {
    if (!subsamples.empty()) {
    // Create a new config with the updated subsamples.
    decrypt_config.reset(new DecryptConfig(
        decrypt_config->key_id(),
        decrypt_config->iv(),
        subsamples));
    }
    // else, use the existing config.
  } else if ((audio && is_audio_track_encrypted_) ||
             (video && is_video_track_encrypted_)) {
    // The media pipeline requires a DecryptConfig with an empty |iv|.
    // TODO(ddorwin): Refactor so we do not need a fake key ID ("1");
    decrypt_config.reset(
        new DecryptConfig("1", "", std::vector<SubsampleEntry>()));
  }

  StreamParserBuffer::Type buffer_type = audio ? DemuxerStream::AUDIO :
      DemuxerStream::VIDEO;

  // TODO(wolenetz/acolwell): Validate and use a common cross-parser TrackId
  // type and allow multiple tracks for same media type, if applicable. See
  // https://crbug.com/341581.
  scoped_refptr<StreamParserBuffer> stream_buf =
      StreamParserBuffer::CopyFrom(&frame_buf[0], frame_buf.size(),
                                   runs_->is_keyframe(), buffer_type, 0);

  if (decrypt_config)
    stream_buf->set_decrypt_config(decrypt_config.Pass());

  stream_buf->set_duration(runs_->duration());
  stream_buf->set_timestamp(runs_->cts());
  stream_buf->SetDecodeTimestamp(runs_->dts());

  DVLOG(3) << "Pushing frame: aud=" << audio
           << ", key=" << runs_->is_keyframe()
           << ", dur=" << runs_->duration().InMilliseconds()
           << ", dts=" << runs_->dts().InMilliseconds()
           << ", cts=" << runs_->cts().InMilliseconds()
           << ", size=" << runs_->sample_size();

  if (audio) {
    audio_buffers->push_back(stream_buf);
  } else {
    video_buffers->push_back(stream_buf);
  }

  runs_->AdvanceSample();
  return true;
}

bool MP4StreamParser::SendAndFlushSamples(BufferQueue* audio_buffers,
                                          BufferQueue* video_buffers) {
  if (audio_buffers->empty() && video_buffers->empty())
    return true;

  TextBufferQueueMap empty_text_map;
  bool success = new_buffers_cb_.Run(*audio_buffers,
                                     *video_buffers,
                                     empty_text_map);
  audio_buffers->clear();
  video_buffers->clear();
  return success;
}

bool MP4StreamParser::ReadAndDiscardMDATsUntil(const int64 offset) {
  bool err = false;
  while (mdat_tail_ < offset) {
    const uint8* buf;
    int size;
    queue_.PeekAt(mdat_tail_, &buf, &size);

    FourCC type;
    int box_sz;
    if (!BoxReader::StartTopLevelBox(buf, size, log_cb_,
                                     &type, &box_sz, &err))
      break;

    if (type != FOURCC_MDAT) {
      MEDIA_LOG(log_cb_) << "Unexpected box type while parsing MDATs: "
                         << FourCCToString(type);
    }
    mdat_tail_ += box_sz;
  }
  queue_.Trim(std::min(mdat_tail_, offset));
  return !err;
}

void MP4StreamParser::ChangeState(State new_state) {
  DVLOG(2) << "Changing state: " << new_state;
  state_ = new_state;
}

}  // namespace mp4
}  // namespace media
/* [<][>][^][v][top][bottom][index][help] */
root/media/formats/mp4/mp4_stream_parser.cc

DEFINITIONS
