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// 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.
//
// THREAD SAFETY
//
// This class is generally not thread safe. Callers should ensure thread safety.
// For instance, the |sink_lock_| in WebAudioSourceProvider synchronizes access
// to this object across the main thread (for WebAudio APIs) and the
// media thread (for HTMLMediaElement APIs).
//
// The one exception is protection for |volume_| via |volume_lock_|. This lock
// prevents races between SetVolume() (called on any thread) and ProvideInput
// (called on audio device thread). See http://crbug.com/588992.
#ifndef MEDIA_BASE_AUDIO_RENDERER_MIXER_INPUT_H_
#define MEDIA_BASE_AUDIO_RENDERER_MIXER_INPUT_H_
#include <string>
#include "base/callback.h"
#include "base/macros.h"
#include "base/synchronization/lock.h"
#include "base/thread_annotations.h"
#include "media/base/audio_converter.h"
#include "media/base/audio_latency.h"
#include "media/base/audio_renderer_sink.h"
namespace media {
class AudioRendererMixerPool;
class AudioRendererMixer;
class MEDIA_EXPORT AudioRendererMixerInput
: public SwitchableAudioRendererSink,
public AudioConverter::InputCallback {
public:
AudioRendererMixerInput(AudioRendererMixerPool* mixer_pool,
int owner_id,
const std::string& device_id,
AudioLatency::LatencyType latency);
// SwitchableAudioRendererSink implementation.
void Start() override;
void Stop() override;
void Play() override;
void Pause() override;
bool SetVolume(double volume) override;
OutputDeviceInfo GetOutputDeviceInfo() override;
bool IsOptimizedForHardwareParameters() override;
void Initialize(const AudioParameters& params,
AudioRendererSink::RenderCallback* renderer) override;
void SwitchOutputDevice(const std::string& device_id,
OutputDeviceStatusCB callback) override;
// This is expected to be called on the audio rendering thread. The caller
// must ensure that this input has been added to a mixer before calling the
// function, and that it is not removed from the mixer before this function
// returns.
bool CurrentThreadIsRenderingThread() override;
// Called by AudioRendererMixer when an error occurs.
void OnRenderError();
protected:
~AudioRendererMixerInput() override;
private:
friend class AudioRendererMixerInputTest;
// Pool to obtain mixers from / return them to.
AudioRendererMixerPool* const mixer_pool_;
// Protect |volume_|, accessed by separate threads in ProvideInput() and
// SetVolume().
base::Lock volume_lock_;
bool started_;
bool playing_;
double volume_ GUARDED_BY(volume_lock_);
// AudioConverter::InputCallback implementation.
double ProvideInput(AudioBus* audio_bus, uint32_t frames_delayed) override;
// AudioParameters received during Initialize().
AudioParameters params_;
const int owner_id_;
std::string device_id_; // ID of hardware device to use
const AudioLatency::LatencyType latency_;
// AudioRendererMixer obtained from mixer pool during Initialize(),
// guaranteed to live (at least) until it is returned to the pool.
AudioRendererMixer* mixer_;
// Source of audio data which is provided to the mixer.
AudioRendererSink::RenderCallback* callback_;
// Error callback for handing to AudioRendererMixer.
const base::Closure error_cb_;
DISALLOW_COPY_AND_ASSIGN(AudioRendererMixerInput);
};
} // namespace media
#endif // MEDIA_BASE_AUDIO_RENDERER_MIXER_INPUT_H_