OscillatorNode.h   [plain text]

/*
 * Copyright (C) 2012, Google Inc. All rights reserved.
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#pragma once

#include "AudioScheduledSourceNode.h"
#include <wtf/Lock.h>

namespace WebCore {

class PeriodicWave;

// OscillatorNode is an audio generator of periodic waveforms.

class OscillatorNode final : public AudioScheduledSourceNode {
public:
    // The waveform type.
    enum class Type {
        Sine,
        Square,
        Sawtooth,
        Triangle,
        Custom
    };

    static Ref<OscillatorNode> create(AudioContext&, float sampleRate);

    virtual ~OscillatorNode();

    Type type() const { return m_type; }
    ExceptionOr<void> setType(Type);

    AudioParam* frequency() { return m_frequency.get(); }
    AudioParam* detune() { return m_detune.get(); }

    void setPeriodicWave(PeriodicWave*);

private:
    OscillatorNode(AudioContext&, float sampleRate);

    void process(size_t framesToProcess) final;
    void reset() final;

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

    // Returns true if there are sample-accurate timeline parameter changes.
    bool calculateSampleAccuratePhaseIncrements(size_t framesToProcess);

    bool propagatesSilence() const final;

    // One of the waveform types defined in the enum.
    Type m_type { Type::Sine };
    
    // Frequency value in Hertz.
    RefPtr<AudioParam> m_frequency;

    // Detune value (deviating from the frequency) in Cents.
    RefPtr<AudioParam> m_detune;

    bool m_firstRender;

    // m_virtualReadIndex is a sample-frame index into our buffer representing the current playback position.
    // Since it's floating-point, it has sub-sample accuracy.
    double m_virtualReadIndex;

    // This synchronizes process().
    mutable Lock m_processMutex;

    // Stores sample-accurate values calculated according to frequency and detune.
    AudioFloatArray m_phaseIncrements;
    AudioFloatArray m_detuneValues;
    
    RefPtr<PeriodicWave> m_periodicWave;

    // Cache the wave tables for different waveform types, except CUSTOM.
    static PeriodicWave* s_periodicWaveSine;
    static PeriodicWave* s_periodicWaveSquare;
    static PeriodicWave* s_periodicWaveSawtooth;
    static PeriodicWave* s_periodicWaveTriangle;
};

} // namespace WebCore