tor-browser

The Tor Browser
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MediaMetadataManager.h (3470B)

      1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
      2 /* vim:set ts=2 sw=2 sts=2 et cindent: */
      3 /* This Source Code Form is subject to the terms of the Mozilla Public
      4 * License, v. 2.0. If a copy of the MPL was not distributed with this
      5 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
      6 
      7 #if !defined(MediaMetadataManager_h__)
      8 #  define MediaMetadataManager_h__
      9 
     10 #  include "MediaEventSource.h"
     11 #  include "TimeUnits.h"
     12 #  include "VideoUtils.h"
     13 #  include "mozilla/AbstractThread.h"
     14 #  include "mozilla/LinkedList.h"
     15 
     16 namespace mozilla {
     17 
     18 class TimedMetadata;
     19 typedef MediaEventProducerExc<TimedMetadata> TimedMetadataEventProducer;
     20 typedef MediaEventSourceExc<TimedMetadata> TimedMetadataEventSource;
     21 
     22 // A struct that contains the metadata of a media, and the time at which those
     23 // metadata should start to be reported.
     24 class TimedMetadata : public LinkedListElement<TimedMetadata> {
     25 public:
     26  TimedMetadata(const media::TimeUnit& aPublishTime,
     27                UniquePtr<MetadataTags>&& aTags, UniquePtr<MediaInfo>&& aInfo)
     28      : mPublishTime(aPublishTime),
     29        mTags(std::move(aTags)),
     30        mInfo(std::move(aInfo)) {}
     31 
     32  // Define our move constructor because we don't want to move the members of
     33  // LinkedListElement to change the list.
     34  TimedMetadata(TimedMetadata&& aOther)
     35      : mPublishTime(aOther.mPublishTime),
     36        mTags(std::move(aOther.mTags)),
     37        mInfo(std::move(aOther.mInfo)) {}
     38 
     39  // The time, in microseconds, at which those metadata should be available.
     40  media::TimeUnit mPublishTime;
     41  // The metadata. The ownership is transfered to the element when dispatching
     42  // to the main threads.
     43  UniquePtr<MetadataTags> mTags;
     44  // The media info, including the info of audio tracks and video tracks.
     45  // The ownership is transfered to MediaDecoder when dispatching to the
     46  // main thread.
     47  UniquePtr<MediaInfo> mInfo;
     48 };
     49 
     50 // This class encapsulate the logic to give the metadata from the reader to
     51 // the content, at the right time.
     52 class MediaMetadataManager {
     53 public:
     54  ~MediaMetadataManager() {
     55    TimedMetadata* element;
     56    while ((element = mMetadataQueue.popFirst()) != nullptr) {
     57      delete element;
     58    }
     59  }
     60 
     61  // Connect to an event source to receive TimedMetadata events.
     62  void Connect(TimedMetadataEventSource& aEvent, AbstractThread* aThread) {
     63    mListener =
     64        aEvent.Connect(aThread, this, &MediaMetadataManager::OnMetadataQueued);
     65  }
     66 
     67  // Stop receiving TimedMetadata events.
     68  void Disconnect() { mListener.Disconnect(); }
     69 
     70  // Return an event source through which we will send TimedMetadata events
     71  // when playback position reaches the publish time.
     72  TimedMetadataEventSource& TimedMetadataEvent() { return mTimedMetadataEvent; }
     73 
     74  void DispatchMetadataIfNeeded(const media::TimeUnit& aCurrentTime) {
     75    TimedMetadata* metadata = mMetadataQueue.getFirst();
     76    while (metadata && aCurrentTime >= metadata->mPublishTime) {
     77      // Our listener will figure out what to do with TimedMetadata.
     78      mTimedMetadataEvent.Notify(std::move(*metadata));
     79      delete mMetadataQueue.popFirst();
     80      metadata = mMetadataQueue.getFirst();
     81    }
     82  }
     83 
     84 protected:
     85  void OnMetadataQueued(TimedMetadata&& aMetadata) {
     86    mMetadataQueue.insertBack(new TimedMetadata(std::move(aMetadata)));
     87  }
     88 
     89  LinkedList<TimedMetadata> mMetadataQueue;
     90  MediaEventListener mListener;
     91  TimedMetadataEventProducer mTimedMetadataEvent;
     92 };
     93 
     94 }  // namespace mozilla
     95 
     96 #endif