text: /*
   *  Copyright 2011 The WebRTC project authors. All Rights Reserved.
   *
   *  Use of this source code is governed by a BSD-style license
   *  that can be found in the LICENSE file in the root of the source
   *  tree. An additional intellectual property rights grant can be found
   *  in the file PATENTS.  All contributing project authors may
   *  be found in the AUTHORS file in the root of the source tree.
   */
  
  #include "pc/audio_track.h"
  
  #include "rtc_base/checks.h"
  #include "rtc_base/ref_counted_object.h"
  
  namespace webrtc {
  
  // static
  rtc::scoped_refptr<AudioTrack> AudioTrack::Create(
      const std::string& id,
      const rtc::scoped_refptr<AudioSourceInterface>& source) {
    return rtc::make_ref_counted<AudioTrack>(id, source);
  }
  
  AudioTrack::AudioTrack(const std::string& label,
                         const rtc::scoped_refptr<AudioSourceInterface>& source)
      : MediaStreamTrack<AudioTrackInterface>(label), audio_source_(source) {
    if (audio_source_) {
      audio_source_->RegisterObserver(this);
      OnChanged();
    }
  }
  
  AudioTrack::~AudioTrack() {
    RTC_DCHECK_RUN_ON(&thread_checker_);
    set_state(MediaStreamTrackInterface::kEnded);
    if (audio_source_)
      audio_source_->UnregisterObserver(this);
  }
  
  std::string AudioTrack::kind() const {
    return kAudioKind;
  }
  
  AudioSourceInterface* AudioTrack::GetSource() const {
    // Callable from any thread.
    return audio_source_.get();
  }
  
  void AudioTrack::AddSink(AudioTrackSinkInterface* sink) {
    RTC_DCHECK_RUN_ON(&thread_checker_);
    if (audio_source_)
      audio_source_->AddSink(sink);
  }
  
  void AudioTrack::RemoveSink(AudioTrackSinkInterface* sink) {
    RTC_DCHECK_RUN_ON(&thread_checker_);
    if (audio_source_)
      audio_source_->RemoveSink(sink);
  }
  
  void AudioTrack::OnChanged() {
    RTC_DCHECK_RUN_ON(&thread_checker_);
    if (audio_source_->state() == MediaSourceInterface::kEnded) {
      set_state(kEnded);
    } else {
      set_state(kLive);
    }
  }
  
  }  // namespace webrtc
  