Source/WebCore/Modules/webaudio/AudioDestinationNode.h

/*
 * Copyright (C) 2010, Google Inc. All rights reserved.
 * Copyright (C) 2020-2021, Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
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#pragma once

#include "AudioNode.h"
#include <wtf/CompletionHandler.h>

namespace WebCore {

class AudioBus;
struct AudioIOPosition;

class AudioDestinationNode : public AudioNode {
    WTF_MAKE_ISO_ALLOCATED(AudioDestinationNode);
public:
    ~AudioDestinationNode();
    
    // AudioNode   
    void process(size_t) final { } // we're pulled by hardware so this is never called

    float sampleRate() const final { return m_sampleRate; }

    size_t currentSampleFrame() const { return m_currentSampleFrame; }
    double currentTime() const { return currentSampleFrame() / static_cast<double>(sampleRate()); }

    virtual unsigned maxChannelCount() const = 0;

    // Enable local/live input for the specified device.
    virtual void enableInput(const String& inputDeviceId) = 0;

    virtual void startRendering(CompletionHandler<void(std::optional<Exception>&&)>&&) = 0;
    virtual void restartRendering() { }

    // AudioDestinationNodes are owned by the BaseAudioContext so we forward the refcounting to its BaseAudioContext.
    void ref() final;
    void deref() final;

protected:
    AudioDestinationNode(BaseAudioContext&, float sampleRate);

    double tailTime() const final { return 0; }
    double latencyTime() const final { return 0; }

    void renderQuantum(AudioBus* destinationBus, size_t numberOfFrames, const AudioIOPosition& outputPosition);

private:
    // Counts the number of sample-frames processed by the destination.
    std::atomic<size_t> m_currentSampleFrame { 0 };
    float m_sampleRate;
};

} // namespace WebCore