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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.
// AudioOutputMixer is a class that implements browser-side audio mixer.
// AudioOutputMixer implements both AudioOutputDispatcher and
// AudioSourceCallback interfaces.
#include <map>
#include "base/basictypes.h"
#include "base/memory/ref_counted.h"
#include "base/memory/scoped_ptr.h"
#include "base/memory/weak_ptr.h"
#include "base/synchronization/lock.h"
#include "base/timer.h"
#include "media/audio/audio_io.h"
#include "media/audio/audio_manager.h"
#include "media/audio/audio_output_dispatcher.h"
#include "media/audio/audio_parameters.h"
namespace media {
class MEDIA_EXPORT AudioOutputMixer
: public AudioOutputDispatcher,
public AudioOutputStream::AudioSourceCallback {
AudioOutputMixer(AudioManager* audio_manager,
const AudioParameters& params,
const base::TimeDelta& close_delay);
// AudioOutputDispatcher interface.
virtual bool OpenStream() OVERRIDE;
virtual bool StartStream(AudioOutputStream::AudioSourceCallback* callback,
AudioOutputProxy* stream_proxy) OVERRIDE;
virtual void StopStream(AudioOutputProxy* stream_proxy) OVERRIDE;
virtual void StreamVolumeSet(AudioOutputProxy* stream_proxy,
double volume) OVERRIDE;
virtual void CloseStream(AudioOutputProxy* stream_proxy) OVERRIDE;
virtual void Shutdown() OVERRIDE;
// AudioSourceCallback interface.
virtual uint32 OnMoreData(uint8* dest,
uint32 max_size,
AudioBuffersState buffers_state) OVERRIDE;
virtual void OnError(AudioOutputStream* stream, int code) OVERRIDE;
virtual void WaitTillDataReady() OVERRIDE;
friend class base::RefCountedThreadSafe<AudioOutputMixer>;
virtual ~AudioOutputMixer();
// Called by |close_timer_|. Closes physical stream.
void ClosePhysicalStream();
// The |lock_| must be acquired whenever we modify |proxies_| in the audio
// manager thread or accessing it in the hardware audio thread. Read in the
// audio manager thread is safe.
base::Lock lock_;
// List of audio output proxies currently being played.
// For every proxy we store aux structure containing data necessary for
// mixing.
struct ProxyData {
AudioOutputStream::AudioSourceCallback* audio_source_callback;
double volume;
int pending_bytes;
typedef std::map<AudioOutputProxy*, ProxyData> ProxyMap;
ProxyMap proxies_;
// Physical stream for this mixer.
scoped_ptr<AudioOutputStream> physical_stream_;
// Temporary buffer used when mixing. Allocated in the constructor
// to avoid constant allocation/deallocation in the callback.
scoped_array<uint8> mixer_data_;
// Used to post delayed tasks to ourselves that we cancel inside Shutdown().
base::WeakPtrFactory<AudioOutputMixer> weak_this_;
base::DelayTimer<AudioOutputMixer> close_timer_;
// Size of data in all in-flight buffers.
int pending_bytes_;
} // namespace media