BiquadProcessor.h   [plain text]

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

#include "AudioDSPKernel.h"
#include "AudioDSPKernelProcessor.h"
#include "AudioNode.h"
#include "AudioParam.h"
#include "Biquad.h"
#include "BiquadFilterType.h"
#include <memory>
#include <wtf/RefPtr.h>

namespace WebCore {

// BiquadProcessor is an AudioDSPKernelProcessor which uses Biquad objects to implement several common filters.

class BiquadProcessor final : public AudioDSPKernelProcessor {
    WTF_MAKE_FAST_ALLOCATED;
public:
    BiquadProcessor(BaseAudioContext&, float sampleRate, size_t numberOfChannels, bool autoInitialize);

    virtual ~BiquadProcessor();
    
    std::unique_ptr<AudioDSPKernel> createKernel() override;
        
    void process(const AudioBus* source, AudioBus* destination, size_t framesToProcess) override;
    void processOnlyAudioParams(size_t framesToProcess) final;

    // Get the magnitude and phase response of the filter at the given
    // set of frequencies (in Hz). The phase response is in radians.
    void getFrequencyResponse(unsigned nFrequencies, const float* frequencyHz, float* magResponse, float* phaseResponse);

    void checkForDirtyCoefficients();
    
    bool filterCoefficientsDirty() const { return m_filterCoefficientsDirty; }
    bool hasSampleAccurateValues() const { return m_hasSampleAccurateValues; }

    AudioParam& parameter1() { return m_parameter1.get(); }
    AudioParam& parameter2() { return m_parameter2.get(); }
    AudioParam& parameter3() { return m_parameter3.get(); }
    AudioParam& parameter4() { return m_parameter4.get(); }

    BiquadFilterType type() const { return m_type; }
    void setType(BiquadFilterType);

    bool shouldUseARate() const { return m_shouldUseARate; }

private:
    BiquadFilterType m_type { BiquadFilterType::Lowpass };

    Ref<AudioParam> m_parameter1;
    Ref<AudioParam> m_parameter2;
    Ref<AudioParam> m_parameter3;
    Ref<AudioParam> m_parameter4;

    // so DSP kernels know when to re-compute coefficients
    bool m_filterCoefficientsDirty { true };

    // Set to true if any of the filter parameters are sample-accurate.
    bool m_hasSampleAccurateValues { false };

    bool m_shouldUseARate { true };
};

} // namespace WebCore