remote_audio_source.h

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/*

 *  Copyright 2014 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.

*/

#ifndef PC_REMOTE_AUDIO_SOURCE_H_

#define PC_REMOTE_AUDIO_SOURCE_H_

#include <stdint.h>

#include <list>

#include <string>

#include "absl/types/optional.h"

#include "api/call/audio_sink.h"

#include "api/media_stream_interface.h"

#include "api/notifier.h"

#include "api/task_queue/task_queue_base.h"

#include "media/base/media_channel.h"

#include "rtc_base/synchronization/mutex.h"

namespace webrtc {

// This class implements the audio source used by the remote audio track.

// This class works by configuring itself as a sink with the underlying media

// engine, then when receiving data will fan out to all added sinks.

class RemoteAudioSource : public Notifier<AudioSourceInterface> {

 public:

  // In Unified Plan, receivers map to m= sections and their tracks and sources

  // survive SSRCs being reconfigured. The life cycle of the remote audio source

  // is associated with the life cycle of the m= section, and thus even if an

  // audio channel is destroyed the RemoteAudioSource should kSurvive.

//

  // In Plan B however, remote audio sources map 1:1 with an SSRCs and if an

  // audio channel is destroyed, the RemoteAudioSource should kEnd.

  enum class OnAudioChannelGoneAction {

    kSurvive,

    kEnd,

};

  explicit RemoteAudioSource(

      TaskQueueBase* worker_thread,

      OnAudioChannelGoneAction on_audio_channel_gone_action);

  // Register and unregister remote audio source with the underlying media

  // engine.

  void Start(cricket::VoiceMediaReceiveChannelInterface* media_channel,

             absl::optional<uint32_t> ssrc);

  void Stop(cricket::VoiceMediaReceiveChannelInterface* media_channel,

            absl::optional<uint32_t> ssrc);

  void SetState(SourceState new_state);

  // MediaSourceInterface implementation.

  MediaSourceInterface::SourceState state() const override;

  bool remote() const override;

  // AudioSourceInterface implementation.

  void SetVolume(double volume) override;

  void RegisterAudioObserver(AudioObserver* observer) override;

  void UnregisterAudioObserver(AudioObserver* observer) override;

  void AddSink(AudioTrackSinkInterface* sink) override;

  void RemoveSink(AudioTrackSinkInterface* sink) override;

 protected:

  ~RemoteAudioSource() override;

 private:

  // These are callbacks from the media engine.

  class AudioDataProxy;

  void OnData(const AudioSinkInterface::Data& audio);

  void OnAudioChannelGone();

  TaskQueueBase* const main_thread_;

  TaskQueueBase* const worker_thread_;

  const OnAudioChannelGoneAction on_audio_channel_gone_action_;

  std::list<AudioObserver*> audio_observers_;

  Mutex sink_lock_;

  std::list<AudioTrackSinkInterface*> sinks_;

  SourceState state_;

};

}  // namespace webrtc

#endif  // PC_REMOTE_AUDIO_SOURCE_H_