root/media/formats/webm/webm_stream_parser.cc

DEFINITIONS

1. parsing_cluster_
2. Init
3. Flush
4. ChangeState
5. ParseInfoAndTracks
6. ParseCluster
7. FireNeedKey

// 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/webm/webm_stream_parser.h"

#include <string>

#include "base/callback.h"
#include "base/callback_helpers.h"
#include "base/logging.h"
#include "media/formats/webm/webm_cluster_parser.h"
#include "media/formats/webm/webm_constants.h"
#include "media/formats/webm/webm_content_encodings.h"
#include "media/formats/webm/webm_crypto_helpers.h"
#include "media/formats/webm/webm_info_parser.h"
#include "media/formats/webm/webm_tracks_parser.h"

namespace media {

WebMStreamParser::WebMStreamParser()
    : state_(kWaitingForInit),
      parsing_cluster_(false) {
}

WebMStreamParser::~WebMStreamParser() {
}

void WebMStreamParser::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(!new_segment_cb.is_null());
  DCHECK(!end_of_segment_cb.is_null());

  ChangeState(kParsingHeaders);
  init_cb_ = init_cb;
  config_cb_ = config_cb;
  new_buffers_cb_ = new_buffers_cb;
  ignore_text_tracks_ = ignore_text_tracks;
  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 WebMStreamParser::Flush() {
  DCHECK_NE(state_, kWaitingForInit);

  byte_queue_.Reset();
  parsing_cluster_ = false;

  if (state_ != kParsingClusters)
    return;

  cluster_parser_->Reset();
}

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

  if (state_ == kError)
    return false;

  byte_queue_.Push(buf, size);

  int result = 0;
  int bytes_parsed = 0;
  const uint8* cur = NULL;
  int cur_size = 0;

  byte_queue_.Peek(&cur, &cur_size);
  while (cur_size > 0) {
    State oldState = state_;
    switch (state_) {
      case kParsingHeaders:
        result = ParseInfoAndTracks(cur, cur_size);
        break;

      case kParsingClusters:
        result = ParseCluster(cur, cur_size);
        break;

      case kWaitingForInit:
      case kError:
        return false;
    }

    if (result < 0) {
      ChangeState(kError);
      return false;
    }

    if (state_ == oldState && result == 0)
      break;

    DCHECK_GE(result, 0);
    cur += result;
    cur_size -= result;
    bytes_parsed += result;
  }

  byte_queue_.Pop(bytes_parsed);
  return true;
}

void WebMStreamParser::ChangeState(State new_state) {
  DVLOG(1) << "ChangeState() : " << state_ << " -> " << new_state;
  state_ = new_state;
}

int WebMStreamParser::ParseInfoAndTracks(const uint8* data, int size) {
  DVLOG(2) << "ParseInfoAndTracks()";
  DCHECK(data);
  DCHECK_GT(size, 0);

  const uint8* cur = data;
  int cur_size = size;
  int bytes_parsed = 0;

  int id;
  int64 element_size;
  int result = WebMParseElementHeader(cur, cur_size, &id, &element_size);

  if (result <= 0)
    return result;

  switch (id) {
    case kWebMIdEBMLHeader:
    case kWebMIdSeekHead:
    case kWebMIdVoid:
    case kWebMIdCRC32:
    case kWebMIdCues:
    case kWebMIdChapters:
      if (cur_size < (result + element_size)) {
        // We don't have the whole element yet. Signal we need more data.
        return 0;
      }
      // Skip the element.
      return result + element_size;
      break;
    case kWebMIdSegment:
      // Just consume the segment header.
      return result;
      break;
    case kWebMIdInfo:
      // We've found the element we are looking for.
      break;
    default: {
      MEDIA_LOG(log_cb_) << "Unexpected element ID 0x" << std::hex << id;
      return -1;
    }
  }

  WebMInfoParser info_parser;
  result = info_parser.Parse(cur, cur_size);

  if (result <= 0)
    return result;

  cur += result;
  cur_size -= result;
  bytes_parsed += result;

  WebMTracksParser tracks_parser(log_cb_, ignore_text_tracks_);
  result = tracks_parser.Parse(cur, cur_size);

  if (result <= 0)
    return result;

  bytes_parsed += result;

  double timecode_scale_in_us = info_parser.timecode_scale() / 1000.0;
  base::TimeDelta duration = kInfiniteDuration();

  if (info_parser.duration() > 0) {
    int64 duration_in_us = info_parser.duration() * timecode_scale_in_us;
    duration = base::TimeDelta::FromMicroseconds(duration_in_us);
  }

  const AudioDecoderConfig& audio_config = tracks_parser.audio_decoder_config();
  if (audio_config.is_encrypted())
    FireNeedKey(tracks_parser.audio_encryption_key_id());

  const VideoDecoderConfig& video_config = tracks_parser.video_decoder_config();
  if (video_config.is_encrypted())
    FireNeedKey(tracks_parser.video_encryption_key_id());

  if (!config_cb_.Run(audio_config,
                      video_config,
                      tracks_parser.text_tracks())) {
    DVLOG(1) << "New config data isn't allowed.";
    return -1;
  }


  cluster_parser_.reset(new WebMClusterParser(
      info_parser.timecode_scale(),
      tracks_parser.audio_track_num(),
      tracks_parser.GetAudioDefaultDuration(timecode_scale_in_us),
      tracks_parser.video_track_num(),
      tracks_parser.GetVideoDefaultDuration(timecode_scale_in_us),
      tracks_parser.text_tracks(),
      tracks_parser.ignored_tracks(),
      tracks_parser.audio_encryption_key_id(),
      tracks_parser.video_encryption_key_id(),
      log_cb_));

  ChangeState(kParsingClusters);

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

  return bytes_parsed;
}

int WebMStreamParser::ParseCluster(const uint8* data, int size) {
  if (!cluster_parser_)
    return -1;

  int id;
  int64 element_size;
  int result = WebMParseElementHeader(data, size, &id, &element_size);

  if (result <= 0)
    return result;

  // TODO(matthewjheaney): implement support for chapters
  if (id == kWebMIdCues || id == kWebMIdChapters) {
    // TODO(wolenetz): Handle unknown-sized cluster parse completion correctly.
    // See http://crbug.com/335676.
    if (size < (result + element_size)) {
      // We don't have the whole element yet. Signal we need more data.
      return 0;
    }
    // Skip the element.
    return result + element_size;
  }

  if (id == kWebMIdEBMLHeader) {
    // TODO(wolenetz): Handle unknown-sized cluster parse completion correctly.
    // See http://crbug.com/335676.
    ChangeState(kParsingHeaders);
    return 0;
  }

  int bytes_parsed = cluster_parser_->Parse(data, size);

  if (bytes_parsed <= 0)
    return bytes_parsed;

  // If cluster detected, immediately notify new segment if we have not already
  // done this.
  if (id == kWebMIdCluster && !parsing_cluster_) {
    parsing_cluster_ = true;
    new_segment_cb_.Run();
  }

  const BufferQueue& audio_buffers = cluster_parser_->GetAudioBuffers();
  const BufferQueue& video_buffers = cluster_parser_->GetVideoBuffers();
  const TextBufferQueueMap& text_map = cluster_parser_->GetTextBuffers();

  bool cluster_ended = cluster_parser_->cluster_ended();

  if ((!audio_buffers.empty() || !video_buffers.empty() || !text_map.empty()) &&
      !new_buffers_cb_.Run(audio_buffers, video_buffers, text_map)) {
    return -1;
  }

  if (cluster_ended) {
    parsing_cluster_ = false;
    end_of_segment_cb_.Run();
  }

  return bytes_parsed;
}

void WebMStreamParser::FireNeedKey(const std::string& key_id) {
  std::vector<uint8> key_id_vector(key_id.begin(), key_id.end());
  need_key_cb_.Run(kWebMEncryptInitDataType, key_id_vector);
}

}  // namespace media