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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.
// AudioOutputDispatcher dispatches creation and deletion of audio
// output streams. AudioOutputProxy objects use this class to allocate
// and recycle actual audio output streams. When playback is started,
// the proxy calls StreamStarted() to get an output stream that it
// uses to play the sound. When playback is stopped, the proxy returns
// the stream back to the dispatcher by calling StreamStopped().
//
// To avoid opening and closing audio devices more frequently than it
// is neccessary, each dispatcher has a pool of inactive physical
// streams. A stream is closed only if it hasn't been used for a
// certain period of time (specified in the constructor).
//
// AudioManagerBase creates one AudioOutputDispatcher per each
// possible set of audio parameters, i.e. streams with different
// parameters are managed independently.
#ifndef MEDIA_AUDIO_AUDIO_OUTPUT_DISPATCHER_H_
#define MEDIA_AUDIO_AUDIO_OUTPUT_DISPATCHER_H_
#include <vector>
#include "base/basictypes.h"
#include "base/memory/ref_counted.h"
#include "base/timer.h"
#include "media/audio/audio_manager.h"
#include "media/audio/audio_parameters.h"
class AudioOutputStream;
class MessageLoop;
class AudioOutputDispatcher
: public base::RefCountedThreadSafe<AudioOutputDispatcher> {
public:
// |close_delay_ms| specifies delay after the stream is paused until
// the audio device is closed.
AudioOutputDispatcher(AudioManager* audio_manager,
const AudioParameters& params,
int close_delay_ms);
~AudioOutputDispatcher();
// Called by AudioOutputProxy when the stream is closed. Opens a new
// physical stream if there are no pending streams in |streams_|.
// Returns false, if it fails to open it.
bool StreamOpened();
// Called by AudioOutputProxy when the stream is started. If there
// are pending streams in |streams_| then it returns one of them,
// otherwise creates a new one. Returns a physical stream that must
// be used, or NULL if it fails to open audio device. Ownership of
// the result is passed to the caller.
AudioOutputStream* StreamStarted();
// Called by AudioOutputProxy when the stream is stopped. Returns
// |stream| to the pool of pending streams (i.e. |streams_|).
// Ownership of the |stream| is passed to the dispatcher.
void StreamStopped(AudioOutputStream* stream);
// Called by AudioOutputProxy when the stream is closed.
void StreamClosed();
MessageLoop* message_loop();
private:
friend class AudioOutputProxyTest;
// Creates a new physical output stream, opens it and pushes to
// |streams_|. Returns false if the stream couldn't be created or
// opened.
bool CreateAndOpenStream();
// A task scheduled by StreamStarted(). Opens a new stream and puts
// it in |streams_|.
void OpenTask();
// Called by |close_timer_|. Closes all pending stream.
void ClosePendingStreams();
AudioManager* audio_manager_;
MessageLoop* message_loop_;
AudioParameters params_;
size_t paused_proxies_;
std::vector<AudioOutputStream*> streams_;
base::DelayTimer<AudioOutputDispatcher> close_timer_;
DISALLOW_COPY_AND_ASSIGN(AudioOutputDispatcher);
};
#endif // MEDIA_AUDIO_AUDIO_OUTPUT_DISPATCHER_H_
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