Source/platform/audio/AudioDestination.h

/*
 * Copyright (C) 2010 Google Inc. All rights reserved.
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#ifndef AudioDestination_h
#define AudioDestination_h

#include "platform/audio/AudioBus.h"
#include "platform/audio/AudioIOCallback.h"
#include "platform/audio/AudioSourceProvider.h"
#include "public/platform/WebAudioDevice.h"
#include "public/platform/WebVector.h"
#include "wtf/Noncopyable.h"
#include "wtf/text/WTFString.h"

namespace blink {

class AudioFIFO;
class AudioPullFIFO;

// An AudioDestination using Chromium's audio system

class PLATFORM_EXPORT AudioDestination : public WebAudioDevice::RenderCallback, public AudioSourceProvider {
    WTF_MAKE_NONCOPYABLE(AudioDestination);
public:
    AudioDestination(AudioIOCallback&, const String& inputDeviceId, unsigned numberOfInputChannels, unsigned numberOfOutputChannels, float sampleRate);
    virtual ~AudioDestination();

    // Pass in (numberOfInputChannels > 0) if live/local audio input is desired.
    // Port-specific device identification information for live/local input streams can be passed in the inputDeviceId.
    static PassOwnPtr<AudioDestination> create(AudioIOCallback&, const String& inputDeviceId, unsigned numberOfInputChannels, unsigned numberOfOutputChannels, float sampleRate);

    virtual void start();
    virtual void stop();
    bool isPlaying() { return m_isPlaying; }

    float sampleRate() const { return m_sampleRate; }

    // WebAudioDevice::RenderCallback
    virtual void render(const WebVector<float*>& sourceData, const WebVector<float*>& audioData, size_t numberOfFrames) OVERRIDE;

    // AudioSourceProvider
    virtual void provideInput(AudioBus*, size_t framesToProcess) OVERRIDE;

    static float hardwareSampleRate();

    // maxChannelCount() returns the total number of output channels of the audio hardware.
    // A value of 0 indicates that the number of channels cannot be configured and
    // that only stereo (2-channel) destinations can be created.
    // The numberOfOutputChannels parameter of AudioDestination::create() is allowed to
    // be a value: 1 <= numberOfOutputChannels <= maxChannelCount(),
    // or if maxChannelCount() equals 0, then numberOfOutputChannels must be 2.
    static unsigned long maxChannelCount();

private:
    AudioIOCallback& m_callback;
    unsigned m_numberOfOutputChannels;
    RefPtr<AudioBus> m_inputBus;
    RefPtr<AudioBus> m_renderBus;
    float m_sampleRate;
    bool m_isPlaying;
    OwnPtr<WebAudioDevice> m_audioDevice;
    size_t m_callbackBufferSize;

    OwnPtr<AudioFIFO> m_inputFifo;
    OwnPtr<AudioPullFIFO> m_fifo;
};

} // namespace blink

#endif // AudioDestination_h