text: // Copyright (c) 2012 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.
  //
  // A fake implementation of AudioInputStream, useful for testing purpose.
  
  #ifndef MEDIA_AUDIO_FAKE_AUDIO_INPUT_STREAM_H_
  #define MEDIA_AUDIO_FAKE_AUDIO_INPUT_STREAM_H_
  
  #include <memory>
  #include <string>
  #include <vector>
  
  #include "base/callback_forward.h"
  #include "base/macros.h"
  #include "base/memory/scoped_refptr.h"
  #include "base/threading/thread.h"
  #include "media/audio/audio_io.h"
  #include "media/base/audio_parameters.h"
  #include "media/base/fake_audio_worker.h"
  
  namespace media {
  
  class AudioBus;
  class AudioManagerBase;
  
  // This class acts as a fake audio input stream. The default is to generate a
  // beeping sound unless --use-file-for-fake-audio-capture=<file> is specified,
  // in which case the indicated .wav file will be read and played into the
  // stream.
  class MEDIA_EXPORT FakeAudioInputStream
      : public AudioInputStream {
   public:
    static AudioInputStream* MakeFakeStream(
        AudioManagerBase* manager, const AudioParameters& params);
  
    bool Open() override;
    void Start(AudioInputCallback* callback) override;
    void Stop() override;
    void Close() override;
    double GetMaxVolume() override;
    void SetVolume(double volume) override;
    double GetVolume() override;
    bool IsMuted() override;
    bool SetAutomaticGainControl(bool enabled) override;
    bool GetAutomaticGainControl() override;
    void SetOutputDeviceForAec(const std::string& output_device_id) override;
  
    // Generate one beep sound. This method is called by FakeVideoCaptureDevice to
    // test audio/video synchronization. This is a static method because
    // FakeVideoCaptureDevice is disconnected from an audio device. This means
    // only one instance of this class gets to respond, which is okay because we
    // assume there's only one stream for this testing purpose. Furthermore this
    // method will do nothing if --use-file-for-fake-audio-capture is specified
    // since the input stream will be playing from a file instead of beeping.
    // TODO(hclam): Make this non-static. To do this we'll need to fix
    // crbug.com/159053 such that video capture device is aware of audio
    // input stream.
    static void BeepOnce();
  
    // Set the muted state for _all_ FakeAudioInputStreams. The value is global,
    // so it can be set before any FakeAudioInputStreams have been created.
    static void SetGlobalMutedState(bool is_muted);
  
   private:
    FakeAudioInputStream(AudioManagerBase* manager,
                         const AudioParameters& params);
    ~FakeAudioInputStream() override;
  
    std::unique_ptr<AudioOutputStream::AudioSourceCallback> ChooseSource();
    void ReadAudioFromSource(base::TimeTicks ideal_time, base::TimeTicks now);
  
    AudioManagerBase* audio_manager_;
    // |callback_| needs the lock as ReadAudioFromSource reads callback_
    // on the capture thread, while callback_ is set on the audio thread.
    base::Lock callback_lock_;
    AudioInputCallback* callback_ GUARDED_BY(callback_lock_);
    AudioParameters params_;
  
    std::unique_ptr<FakeAudioWorker> fake_audio_worker_;
    std::unique_ptr<AudioOutputStream::AudioSourceCallback> audio_source_;
    std::unique_ptr<media::AudioBus> audio_bus_;
    // We will delete the capture thread on the AudioManager worker task runner
    // since the audio thread is the main UI thread on Mac.
    std::unique_ptr<base::Thread, base::OnTaskRunnerDeleter> capture_thread_;
  
    DISALLOW_COPY_AND_ASSIGN(FakeAudioInputStream);
  };
  
  }  // namespace media
  
  #endif  // MEDIA_AUDIO_FAKE_AUDIO_INPUT_STREAM_H_
  