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// Copyright (c) 2011 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_AUDIO_AUDIO_OUTPUT_STREAM_PROXY_H_
#define MEDIA_AUDIO_AUDIO_OUTPUT_STREAM_PROXY_H_
#include "base/basictypes.h"
#include "base/task.h"
#include "media/audio/audio_io.h"
#include "media/audio/audio_parameters.h"
class AudioOutputDispatcher;
// AudioOutputProxy is an audio otput stream that uses resources more
// efficiently than a regular audio output stream: it opens audio
// device only when sound is playing, i.e. between Start() and Stop()
// (there is still one physical stream per each audio output proxy in
// playing state).
//
// AudioOutputProxy uses AudioOutputDispatcher to open and close
// physical output streams.
class MEDIA_EXPORT AudioOutputProxy : public AudioOutputStream {
public:
// Caller keeps ownership of |dispatcher|.
AudioOutputProxy(AudioOutputDispatcher* dispatcher);
// AudioOutputStream interface.
virtual bool Open();
virtual void Start(AudioSourceCallback* callback);
virtual void Stop();
virtual void SetVolume(double volume);
virtual void GetVolume(double* volume);
virtual void Close();
private:
// Needs to access destructor.
friend class DeleteTask<AudioOutputProxy>;
enum State {
kCreated,
kOpened,
kPlaying,
kClosed,
kError,
};
virtual ~AudioOutputProxy();
scoped_refptr<AudioOutputDispatcher> dispatcher_;
State state_;
// The actual audio stream. Must be set to NULL in any state other
// than kPlaying.
AudioOutputStream* physical_stream_;
// Need to save volume here, so that we can restore it in case the stream
// is stopped, and then started again.
double volume_;
DISALLOW_COPY_AND_ASSIGN(AudioOutputProxy);
};
#endif // MEDIA_AUDIO_AUDIO_OUTPUT_STREAM_PROXY_H_
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