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/*
* Copyright (C) 2010, Google Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
* ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "config.h"
#if ENABLE(WEB_AUDIO)
#include "modules/webaudio/BiquadDSPKernel.h"
#include "platform/FloatConversion.h"
#include <limits.h>
#include "wtf/Vector.h"
namespace blink {
// FIXME: As a recursive linear filter, depending on its parameters, a biquad filter can have
// an infinite tailTime. In practice, Biquad filters do not usually (except for very high resonance values)
// have a tailTime of longer than approx. 200ms. This value could possibly be calculated based on the
// settings of the Biquad.
static const double MaxBiquadDelayTime = 0.2;
void BiquadDSPKernel::updateCoefficientsIfNecessary()
{
if (biquadProcessor()->filterCoefficientsDirty()) {
double cutoffFrequency;
double Q;
double gain;
double detune; // in Cents
if (biquadProcessor()->hasSampleAccurateValues()) {
cutoffFrequency = biquadProcessor()->parameter1()->finalValue();
Q = biquadProcessor()->parameter2()->finalValue();
gain = biquadProcessor()->parameter3()->finalValue();
detune = biquadProcessor()->parameter4()->finalValue();
} else {
cutoffFrequency = biquadProcessor()->parameter1()->smoothedValue();
Q = biquadProcessor()->parameter2()->smoothedValue();
gain = biquadProcessor()->parameter3()->smoothedValue();
detune = biquadProcessor()->parameter4()->smoothedValue();
}
updateCoefficients(cutoffFrequency, Q, gain, detune);
}
}
void BiquadDSPKernel::updateCoefficients(double cutoffFrequency, double Q, double gain, double detune)
{
// Convert from Hertz to normalized frequency 0 -> 1.
double nyquist = this->nyquist();
double normalizedFrequency = cutoffFrequency / nyquist;
// Offset frequency by detune.
if (detune)
normalizedFrequency *= pow(2, detune / 1200);
// Configure the biquad with the new filter parameters for the appropriate type of filter.
switch (biquadProcessor()->type()) {
case BiquadProcessor::LowPass:
m_biquad.setLowpassParams(normalizedFrequency, Q);
break;
case BiquadProcessor::HighPass:
m_biquad.setHighpassParams(normalizedFrequency, Q);
break;
case BiquadProcessor::BandPass:
m_biquad.setBandpassParams(normalizedFrequency, Q);
break;
case BiquadProcessor::LowShelf:
m_biquad.setLowShelfParams(normalizedFrequency, gain);
break;
case BiquadProcessor::HighShelf:
m_biquad.setHighShelfParams(normalizedFrequency, gain);
break;
case BiquadProcessor::Peaking:
m_biquad.setPeakingParams(normalizedFrequency, Q, gain);
break;
case BiquadProcessor::Notch:
m_biquad.setNotchParams(normalizedFrequency, Q);
break;
case BiquadProcessor::Allpass:
m_biquad.setAllpassParams(normalizedFrequency, Q);
break;
}
}
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.
// The audio thread can't block on this lock; skip updating the coefficients for this block if
// necessary. We'll get them the next time around.
{
MutexTryLocker tryLocker(m_processLock);
if (tryLocker.locked())
updateCoefficientsIfNecessary();
}
m_biquad.process(source, destination, framesToProcess);
}
void BiquadDSPKernel::getFrequencyResponse(int nFrequencies,
const float* frequencyHz,
float* magResponse,
float* phaseResponse)
{
bool isGood = nFrequencies > 0 && frequencyHz && magResponse && phaseResponse;
ASSERT(isGood);
if (!isGood)
return;
Vector<float> frequency(nFrequencies);
double nyquist = this->nyquist();
// Convert from frequency in Hz to normalized frequency (0 -> 1),
// with 1 equal to the Nyquist frequency.
for (int k = 0; k < nFrequencies; ++k)
frequency[k] = narrowPrecisionToFloat(frequencyHz[k] / nyquist);
double cutoffFrequency;
double Q;
double gain;
double detune; // in Cents
{
// Get a copy of the current biquad filter coefficients so we can update the biquad with
// these values. We need to synchronize with process() to prevent process() from updating
// the filter coefficients while we're trying to access them. The process will update it
// next time around.
//
// The BiquadDSPKernel object here (along with it's Biquad object) is for querying the
// frequency response and is NOT the same as the one in process() which is used for
// performing the actual filtering. This one is is created in
// BiquadProcessor::getFrequencyResponse for this purpose. Both, however, point to the same
// BiquadProcessor object.
//
// FIXME: Simplify this: crbug.com/390266
MutexLocker processLocker(m_processLock);
cutoffFrequency = biquadProcessor()->parameter1()->value();
Q = biquadProcessor()->parameter2()->value();
gain = biquadProcessor()->parameter3()->value();
detune = biquadProcessor()->parameter4()->value();
}
updateCoefficients(cutoffFrequency, Q, gain, detune);
m_biquad.getFrequencyResponse(nFrequencies, frequency.data(), magResponse, phaseResponse);
}
double BiquadDSPKernel::tailTime() const
{
return MaxBiquadDelayTime;
}
double BiquadDSPKernel::latencyTime() const
{
return 0;
}
} // namespace blink
#endif // ENABLE(WEB_AUDIO)
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