text: // 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.
  
  #ifndef MEDIA_CAST_SENDER_AUDIO_SENDER_H_
  #define MEDIA_CAST_SENDER_AUDIO_SENDER_H_
  
  #include <memory>
  
  #include "base/callback.h"
  #include "base/macros.h"
  #include "base/memory/ref_counted.h"
  #include "base/memory/weak_ptr.h"
  #include "base/time/tick_clock.h"
  #include "base/time/time.h"
  #include "media/base/audio_bus.h"
  #include "media/cast/cast_config.h"
  #include "media/cast/cast_sender.h"
  #include "media/cast/sender/frame_sender.h"
  
  namespace media {
  namespace cast {
  
  class AudioEncoder;
  
  // Not thread safe. Only called from the main cast thread.
  // This class owns all objects related to sending audio, objects that create RTP
  // packets, congestion control, audio encoder, parsing and sending of
  // RTCP packets.
  // Additionally it posts a bunch of delayed tasks to the main thread for various
  // timeouts.
  class AudioSender final : public FrameSender {
   public:
    AudioSender(scoped_refptr<CastEnvironment> cast_environment,
                const FrameSenderConfig& audio_config,
                StatusChangeOnceCallback status_change_cb,
                CastTransport* const transport_sender);
  
    ~AudioSender() final;
  
    // Note: It is not guaranteed that |audio_frame| will actually be encoded and
    // sent, if AudioSender detects too many frames in flight.  Therefore, clients
    // should be careful about the rate at which this method is called.
    void InsertAudio(std::unique_ptr<AudioBus> audio_bus,
                     const base::TimeTicks& recorded_time);
  
    base::WeakPtr<AudioSender> AsWeakPtr();
  
   protected:
    int GetNumberOfFramesInEncoder() const final;
    base::TimeDelta GetInFlightMediaDuration() const final;
  
   private:
    // Called by the |audio_encoder_| with the next EncodedFrame to send.
    void OnEncodedAudioFrame(int encoder_bitrate,
                             std::unique_ptr<SenderEncodedFrame> encoded_frame,
                             int samples_skipped);
  
    // Encodes AudioBuses into EncodedFrames.
    std::unique_ptr<AudioEncoder> audio_encoder_;
  
    // The number of audio samples enqueued in |audio_encoder_|.
    int samples_in_encoder_;
  
    // NOTE: Weak pointers must be invalidated before all other member variables.
    base::WeakPtrFactory<AudioSender> weak_factory_{this};
  
    DISALLOW_COPY_AND_ASSIGN(AudioSender);
  };
  
  }  // namespace cast
  }  // namespace media
  
  #endif  // MEDIA_CAST_SENDER_AUDIO_SENDER_H_
  