C++ MediaStream::GetStreamBuffer方法代码示例

void
AudioCaptureStream::ProcessInput(GraphTime aFrom, GraphTime aTo,
                                 uint32_t aFlags)
{
  uint32_t inputCount = mInputs.Length();
  StreamBuffer::Track* track = EnsureTrack(mTrackId);
  // Notify the DOM everything is in order.
  if (!mTrackCreated) {
    for (uint32_t i = 0; i < mListeners.Length(); i++) {
      MediaStreamListener* l = mListeners[i];
      AudioSegment tmp;
      l->NotifyQueuedTrackChanges(
        Graph(), mTrackId, 0, MediaStreamListener::TRACK_EVENT_CREATED, tmp);
      l->NotifyFinishedTrackCreation(Graph());
    }
    mTrackCreated = true;
  }

  // If the captured stream is connected back to a object on the page (be it an
  // HTMLMediaElement with a stream as source, or an AudioContext), a cycle
  // situation occur. This can work if it's an AudioContext with at least one
  // DelayNode, but the MSG will mute the whole cycle otherwise.
  if (mFinished || InMutedCycle() || inputCount == 0) {
    track->Get<AudioSegment>()->AppendNullData(aTo - aFrom);
  } else {
    // We mix down all the tracks of all inputs, to a stereo track. Everything
    // is {up,down}-mixed to stereo.
    mMixer.StartMixing();
    AudioSegment output;
    for (uint32_t i = 0; i < inputCount; i++) {
      MediaStream* s = mInputs[i]->GetSource();
      StreamBuffer::TrackIter tracks(s->GetStreamBuffer(), MediaSegment::AUDIO);
      while (!tracks.IsEnded()) {
        AudioSegment* inputSegment = tracks->Get<AudioSegment>();
        StreamTime inputStart = s->GraphTimeToStreamTimeWithBlocking(aFrom);
        StreamTime inputEnd = s->GraphTimeToStreamTimeWithBlocking(aTo);
        AudioSegment toMix;
        toMix.AppendSlice(*inputSegment, inputStart, inputEnd);
        // Care for streams blocked in the [aTo, aFrom] range.
        if (inputEnd - inputStart < aTo - aFrom) {
          toMix.AppendNullData((aTo - aFrom) - (inputEnd - inputStart));
        }
        toMix.Mix(mMixer, MONO, Graph()->GraphRate());
        tracks.Next();
      }
    }
    // This calls MixerCallback below
    mMixer.FinishMixing();
  }

  // Regardless of the status of the input tracks, we go foward.
  mBuffer.AdvanceKnownTracksTime(GraphTimeToStreamTimeWithBlocking((aTo)));
}

 void TrackUnionStream::ProcessInput(GraphTime aFrom, GraphTime aTo, uint32_t aFlags)
 {
   if (IsFinishedOnGraphThread()) {
     return;
   }
   nsAutoTArray<bool,8> mappedTracksFinished;
   nsAutoTArray<bool,8> mappedTracksWithMatchingInputTracks;
   for (uint32_t i = 0; i < mTrackMap.Length(); ++i) {
     mappedTracksFinished.AppendElement(true);
     mappedTracksWithMatchingInputTracks.AppendElement(false);
   }
   bool allFinished = !mInputs.IsEmpty();
   bool allHaveCurrentData = !mInputs.IsEmpty();
   for (uint32_t i = 0; i < mInputs.Length(); ++i) {
     MediaStream* stream = mInputs[i]->GetSource();
     if (!stream->IsFinishedOnGraphThread()) {
       // XXX we really should check whether 'stream' has finished within time aTo,
       // not just that it's finishing when all its queued data eventually runs
       // out.
       allFinished = false;
     }
     if (!stream->HasCurrentData()) {
       allHaveCurrentData = false;
     }
     bool trackAdded = false;
     for (StreamBuffer::TrackIter tracks(stream->GetStreamBuffer());
          !tracks.IsEnded(); tracks.Next()) {
       bool found = false;
       for (uint32_t j = 0; j < mTrackMap.Length(); ++j) {
         TrackMapEntry* map = &mTrackMap[j];
         if (map->mInputPort == mInputs[i] && map->mInputTrackID == tracks->GetID()) {
           bool trackFinished;
           StreamBuffer::Track* outputTrack = mBuffer.FindTrack(map->mOutputTrackID);
           if (!outputTrack || outputTrack->IsEnded()) {
             trackFinished = true;
           } else {
             CopyTrackData(tracks.get(), j, aFrom, aTo, &trackFinished);
           }
           mappedTracksFinished[j] = trackFinished;
           mappedTracksWithMatchingInputTracks[j] = true;
           found = true;
           break;
         }
       }
       if (!found && (!mFilterCallback || mFilterCallback(tracks.get()))) {
         bool trackFinished = false;
         trackAdded = true;
         uint32_t mapIndex = AddTrack(mInputs[i], tracks.get(), aFrom);
         CopyTrackData(tracks.get(), mapIndex, aFrom, aTo, &trackFinished);
         mappedTracksFinished.AppendElement(trackFinished);
         mappedTracksWithMatchingInputTracks.AppendElement(true);
       }
     }
     if (trackAdded) {
       for (MediaStreamListener* l : mListeners) {
         l->NotifyFinishedTrackCreation(Graph());
       }
     }
   }
   for (int32_t i = mTrackMap.Length() - 1; i >= 0; --i) {
     if (mappedTracksFinished[i]) {
       EndTrack(i);
     } else {
       allFinished = false;
     }
     if (!mappedTracksWithMatchingInputTracks[i]) {
       mTrackMap.RemoveElementAt(i);
     }
   }
   if (allFinished && mAutofinish && (aFlags & ALLOW_FINISH)) {
     // All streams have finished and won't add any more tracks, and
     // all our tracks have actually finished and been removed from our map,
     // so we're finished now.
     FinishOnGraphThread();
   } else {
     mBuffer.AdvanceKnownTracksTime(GraphTimeToStreamTime(aTo));
   }
   if (allHaveCurrentData) {
     // We can make progress if we're not blocked
     mHasCurrentData = true;
   }
 }