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      1 /*
      2  * Copyright (C) 2010, Google Inc. All rights reserved.
      3  *
      4  * Redistribution and use in source and binary forms, with or without
      5  * modification, are permitted provided that the following conditions
      6  * are met:
      7  * 1.  Redistributions of source code must retain the above copyright
      8  *    notice, this list of conditions and the following disclaimer.
      9  * 2.  Redistributions in binary form must reproduce the above copyright
     10  *    notice, this list of conditions and the following disclaimer in the
     11  *    documentation and/or other materials provided with the distribution.
     12  *
     13  * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' AND ANY
     14  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
     15  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
     16  * DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS BE LIABLE FOR ANY
     17  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
     18  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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     20  * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     21  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
     22  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     23  */
     24 
     25 #include "config.h"
     26 
     27 #if ENABLE(WEB_AUDIO)
     28 
     29 #include "modules/webaudio/BiquadDSPKernel.h"
     30 
     31 #include "platform/FloatConversion.h"
     32 #include <limits.h>
     33 #include "wtf/Vector.h"
     34 
     35 namespace WebCore {
     36 
     37 // FIXME: As a recursive linear filter, depending on its parameters, a biquad filter can have
     38 // an infinite tailTime. In practice, Biquad filters do not usually (except for very high resonance values)
     39 // have a tailTime of longer than approx. 200ms. This value could possibly be calculated based on the
     40 // settings of the Biquad.
     41 static const double MaxBiquadDelayTime = 0.2;
     42 
     43 void BiquadDSPKernel::updateCoefficientsIfNecessary(bool useSmoothing, bool forceUpdate)
     44 {
     45     if (forceUpdate || biquadProcessor()->filterCoefficientsDirty()) {
     46         double value1;
     47         double value2;
     48         double gain;
     49         double detune; // in Cents
     50 
     51         if (biquadProcessor()->hasSampleAccurateValues()) {
     52             value1 = biquadProcessor()->parameter1()->finalValue();
     53             value2 = biquadProcessor()->parameter2()->finalValue();
     54             gain = biquadProcessor()->parameter3()->finalValue();
     55             detune = biquadProcessor()->parameter4()->finalValue();
     56         } else if (useSmoothing) {
     57             value1 = biquadProcessor()->parameter1()->smoothedValue();
     58             value2 = biquadProcessor()->parameter2()->smoothedValue();
     59             gain = biquadProcessor()->parameter3()->smoothedValue();
     60             detune = biquadProcessor()->parameter4()->smoothedValue();
     61         } else {
     62             value1 = biquadProcessor()->parameter1()->value();
     63             value2 = biquadProcessor()->parameter2()->value();
     64             gain = biquadProcessor()->parameter3()->value();
     65             detune = biquadProcessor()->parameter4()->value();
     66         }
     67 
     68         // Convert from Hertz to normalized frequency 0 -> 1.
     69         double nyquist = this->nyquist();
     70         double normalizedFrequency = value1 / nyquist;
     71 
     72         // Offset frequency by detune.
     73         if (detune)
     74             normalizedFrequency *= pow(2, detune / 1200);
     75 
     76         // Configure the biquad with the new filter parameters for the appropriate type of filter.
     77         switch (biquadProcessor()->type()) {
     78         case BiquadProcessor::LowPass:
     79             m_biquad.setLowpassParams(normalizedFrequency, value2);
     80             break;
     81 
     82         case BiquadProcessor::HighPass:
     83             m_biquad.setHighpassParams(normalizedFrequency, value2);
     84             break;
     85 
     86         case BiquadProcessor::BandPass:
     87             m_biquad.setBandpassParams(normalizedFrequency, value2);
     88             break;
     89 
     90         case BiquadProcessor::LowShelf:
     91             m_biquad.setLowShelfParams(normalizedFrequency, gain);
     92             break;
     93 
     94         case BiquadProcessor::HighShelf:
     95             m_biquad.setHighShelfParams(normalizedFrequency, gain);
     96             break;
     97 
     98         case BiquadProcessor::Peaking:
     99             m_biquad.setPeakingParams(normalizedFrequency, value2, gain);
    100             break;
    101 
    102         case BiquadProcessor::Notch:
    103             m_biquad.setNotchParams(normalizedFrequency, value2);
    104             break;
    105 
    106         case BiquadProcessor::Allpass:
    107             m_biquad.setAllpassParams(normalizedFrequency, value2);
    108             break;
    109         }
    110     }
    111 }
    112 
    113 void BiquadDSPKernel::process(const float* source, float* destination, size_t framesToProcess)
    114 {
    115     ASSERT(source && destination && biquadProcessor());
    116 
    117     // Recompute filter coefficients if any of the parameters have changed.
    118     // FIXME: as an optimization, implement a way that a Biquad object can simply copy its internal filter coefficients from another Biquad object.
    119     // Then re-factor this code to only run for the first BiquadDSPKernel of each BiquadProcessor.
    120 
    121     updateCoefficientsIfNecessary(true, false);
    122 
    123     m_biquad.process(source, destination, framesToProcess);
    124 }
    125 
    126 void BiquadDSPKernel::getFrequencyResponse(int nFrequencies,
    127                                            const float* frequencyHz,
    128                                            float* magResponse,
    129                                            float* phaseResponse)
    130 {
    131     bool isGood = nFrequencies > 0 && frequencyHz && magResponse && phaseResponse;
    132     ASSERT(isGood);
    133     if (!isGood)
    134         return;
    135 
    136     Vector<float> frequency(nFrequencies);
    137 
    138     double nyquist = this->nyquist();
    139 
    140     // Convert from frequency in Hz to normalized frequency (0 -> 1),
    141     // with 1 equal to the Nyquist frequency.
    142     for (int k = 0; k < nFrequencies; ++k)
    143         frequency[k] = narrowPrecisionToFloat(frequencyHz[k] / nyquist);
    144 
    145     // We want to get the final values of the coefficients and compute
    146     // the response from that instead of some intermediate smoothed
    147     // set. Forcefully update the coefficients even if they are not
    148     // dirty.
    149 
    150     updateCoefficientsIfNecessary(false, true);
    151 
    152     m_biquad.getFrequencyResponse(nFrequencies, frequency.data(), magResponse, phaseResponse);
    153 }
    154 
    155 double BiquadDSPKernel::tailTime() const
    156 {
    157     return MaxBiquadDelayTime;
    158 }
    159 
    160 double BiquadDSPKernel::latencyTime() const
    161 {
    162     return 0;
    163 }
    164 
    165 } // namespace WebCore
    166 
    167 #endif // ENABLE(WEB_AUDIO)
    168