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// Copyright (c) 2009 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.
//
// Audio rendering unit utilizing audio output stream provided by browser
// process through IPC.
//
// Relationship of classes.
//
// AudioRendererHost AudioRendererImpl
// ^ ^
// | |
// v IPC v
// ResourceMessageFilter <---------> AudioMessageFilter
//
// Implementation of interface with audio device is in AudioRendererHost and
// it provides services and entry points in ResourceMessageFilter, allowing
// usage of IPC calls to interact with audio device. AudioMessageFilter acts
// as a portal for IPC calls and does no more than delegation.
//
// Transportation of audio buffer is done by using shared memory, after
// OnCreateStream is executed, OnCreated would be called along with a
// SharedMemoryHandle upon successful creation of audio output stream in the
// browser process. The same piece of shared memory would be used during the
// lifetime of this unit.
//
// This class lives inside three threads during it's lifetime, namely:
// 1. IO thread.
// The thread within which this class receives all the IPC messages and
// IPC communications can only happen in this thread.
// 2. Pipeline thread
// Initialization of filter and proper stopping of filters happens here.
// Properties of this filter is also set in this thread.
// 3. Audio decoder thread (If there's one.)
// Responsible for decoding audio data and gives raw PCM data to this object.
//
// Methods categorized according to the thread(s) they are running on.
//
// Render thread
// +-- CreateFactory()
// | Helper method for construction this class.
// \-- IsMediaFormatSupported()
// Helper method to identify media formats accepted by this class for
// construction.
//
// IO thread (Main thread in render process)
// +-- OnCreateStream()
// | Sends an IPC message to browser to create audio output stream and
// | register this object with AudioMessageFilter.
// |-- OnSetVolume()
// | Sends an IPC message to browser to set volume.
// |-- OnNotifyPacketReady
// | Try to fill the shared memory with decoded audio packet and sends IPC
// | messages to browser if packet is ready.
// |-- OnRequestPacket()
// | Called from AudioMessageFilter when an audio packet requested is
// | received from browser process.
// |-- OnStateChanged()
// | Called from AudioMessageFilter upon state change of the audio output
// | stream in the browser process. Error of the stream is reported here.
// |-- OnCreated()
// | Called from AudioMessageFilter upon successful creation of audio output
// | stream in the browser process, called along with a SharedMemoryHandle.
// |-- OnVolume()
// | Called from AudioMessageFilter about the volume of the audio output
// | stream.
// \-- OnDestroy()
// Release resources that live inside io thread.
//
// Pipeline thread
// +-- AudioRendererImpl()
// | Constructor method.
// |-- ~AudioRendererImpl()
// | Destructor method.
// |-- SetPlaybackRate()
// | Given the playback rate information.
// |-- GetMediaFormat()
// | Obtain the current media format of this unit.
// |-- SetVolume()
// | Given the volume information.
// |-- OnInitialize()
// | Called from AudioRendererBase for initialization event.
// \-- OnStop()
// Called from AudioRendererBase for stop event.
//
// Audio decoder thread (If there's one.)
// \-- OnReadComplete()
// A raw PCM audio packet buffer is received here, this method is called
// from pipeline thread if audio decoder thread does not exist.
#ifndef CHROME_RENDERER_MEDIA_AUDIO_RENDERER_IMPL_H_
#define CHROME_RENDERER_MEDIA_AUDIO_RENDERER_IMPL_H_
#include "base/lock.h"
#include "base/shared_memory.h"
#include "base/waitable_event.h"
#include "chrome/renderer/audio_message_filter.h"
#include "media/audio/audio_output.h"
#include "media/base/factory.h"
#include "media/base/filters.h"
#include "media/filters/audio_renderer_base.h"
class AudioMessageFilter;
class AudioRendererImpl : public media::AudioRendererBase,
public AudioMessageFilter::Delegate {
public:
// Methods called on render thread ------------------------------------------
// Methods called during construction.
static media::FilterFactory* CreateFactory(AudioMessageFilter* filter) {
return new media::FilterFactoryImpl1<AudioRendererImpl,
AudioMessageFilter*>(filter);
}
static bool IsMediaFormatSupported(const media::MediaFormat& format);
// Methods called on IO thread ----------------------------------------------
// AudioMessageFilter::Delegate methods, called by AudioMessageFilter.
void OnRequestPacket();
void OnStateChanged(AudioOutputStream::State state, int info);
void OnCreated(base::SharedMemoryHandle handle, size_t length);
void OnVolume(double left, double right);
// Methods called on pipeline thread ----------------------------------------
// media::MediaFilter implementation.
virtual void SetPlaybackRate(float rate);
// media::AudioRenderer implementation.
virtual void SetVolume(float volume);
protected:
// Methods called on audio renderer thread ----------------------------------
// These methods are called from AudioRendererBase.
virtual bool OnInitialize(const media::MediaFormat& media_format);
virtual void OnStop();
// Called when the decoder completes a Read().
virtual void OnReadComplete(media::Buffer* buffer_in);
private:
friend class media::FilterFactoryImpl1<AudioRendererImpl,
AudioMessageFilter*>;
explicit AudioRendererImpl(AudioMessageFilter* filter);
virtual ~AudioRendererImpl();
// Methods call on IO thread ------------------------------------------------
// The following methods are tasks posted on the IO thread that needs to
// be executed on that thread. They interact with AudioMessageFilter and
// sends IPC messages on that thread.
void OnCreateStream(AudioManager::Format format, int channels,
int sample_rate, int bits_per_sample,
size_t packet_size);
void OnSetVolume(double left, double right);
void OnNotifyPacketReady();
void OnDestroy();
scoped_refptr<AudioMessageFilter> filter_;
// ID of the stream created in the browser process.
int32 stream_id_;
// Memory shared by the browser process for audio buffer.
scoped_ptr<base::SharedMemory> shared_memory_;
size_t shared_memory_size_;
// Message loop for the io thread.
MessageLoop* io_loop_;
Lock lock_;
bool stopped_;
float playback_rate_;
base::WaitableEvent packet_request_event_;
DISALLOW_COPY_AND_ASSIGN(AudioRendererImpl);
};
#endif // CHROME_RENDERER_MEDIA_AUDIO_RENDERER_IMPL_H_
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