Source/WebCore/webaudio/BiquadDSPKernel.cpp

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 * Copyright (C) 2010, Google Inc. All rights reserved.
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#include "config.h"

#if ENABLE(WEB_AUDIO)

#include "BiquadDSPKernel.h"

#include "BiquadProcessor.h"

namespace WebCore {

void BiquadDSPKernel::process(const float* source, float* destination, size_t framesToProcess)
{
    ASSERT(source && destination && biquadProcessor());
    
    // Recompute filter coefficients if any of the parameters have changed.
    // FIXME: as an optimization, implement a way that a Biquad object can simply copy its internal filter coefficients from another Biquad object.
    // Then re-factor this code to only run for the first BiquadDSPKernel of each BiquadProcessor.
    if (biquadProcessor()->filterCoefficientsDirty()) {
        double value1 = biquadProcessor()->parameter1()->smoothedValue();
        double value2 = biquadProcessor()->parameter2()->smoothedValue();
        
        // Convert from Hertz to normalized frequency 0 -> 1.
        double nyquist = this->nyquist();
        double normalizedValue1 = value1 / nyquist;

        // Configure the biquad with the new filter parameters for the appropriate type of filter.
        switch (biquadProcessor()->type()) {
        case BiquadProcessor::LowPass2:
            m_biquad.setLowpassParams(normalizedValue1, value2);
            break;

        case BiquadProcessor::HighPass2:
            m_biquad.setHighpassParams(normalizedValue1, value2);
            break;

        case BiquadProcessor::LowShelf:
            m_biquad.setLowShelfParams(normalizedValue1, value2);
            break;

        // FIXME: add other biquad filter types...
        case BiquadProcessor::Peaking:
        case BiquadProcessor::Allpass:
        case BiquadProcessor::HighShelf:
            break;
        }
    }

    m_biquad.process(source, destination, framesToProcess);
}

} // namespace WebCore

#endif // ENABLE(WEB_AUDIO)