root/BiquadProcessor.h

INCLUDED FROM

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#ifndef BiquadProcessor_h
#define BiquadProcessor_h

#include "core/platform/audio/AudioDSPKernel.h"
#include "core/platform/audio/AudioDSPKernelProcessor.h"
#include "core/platform/audio/Biquad.h"
#include "modules/webaudio/AudioNode.h"
#include "modules/webaudio/AudioParam.h"
#include "wtf/RefPtr.h"

namespace WebCore {

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

class BiquadProcessor : public AudioDSPKernelProcessor {
public:
    enum FilterType {
        LowPass = 0,
        HighPass = 1,
        BandPass = 2,
        LowShelf = 3,
        HighShelf = 4,
        Peaking = 5,
        Notch = 6,
        Allpass = 7
    };

    BiquadProcessor(AudioContext*, float sampleRate, size_t numberOfChannels, bool autoInitialize);

    virtual ~BiquadProcessor();

    virtual PassOwnPtr<AudioDSPKernel> createKernel();

    virtual void process(const AudioBus* source, AudioBus* destination, size_t framesToProcess);

    // 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(int 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(); }

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

private:
    FilterType m_type;

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

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

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

} // namespace WebCore

#endif // BiquadProcessor_h