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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;
     19  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
     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 "core/platform/FloatConversion.h"
     32 #include "modules/webaudio/BiquadProcessor.h"
     33 #include <limits.h>
     34 #include "wtf/Vector.h"
     35 
     36 namespace WebCore {
     37 
     38 // FIXME: As a recursive linear filter, depending on its parameters, a biquad filter can have
     39 // an infinite tailTime. In practice, Biquad filters do not usually (except for very high resonance values)
     40 // have a tailTime of longer than approx. 200ms. This value could possibly be calculated based on the
     41 // settings of the Biquad.
     42 static const double MaxBiquadDelayTime = 0.2;
     43 
     44 void BiquadDSPKernel::updateCoefficientsIfNecessary(bool useSmoothing, bool forceUpdate)
     45 {
     46     if (forceUpdate || biquadProcessor()->filterCoefficientsDirty()) {
     47         double value1;
     48         double value2;
     49         double gain;
     50         double detune; // in Cents
     51 
     52         if (biquadProcessor()->hasSampleAccurateValues()) {
     53             value1 = biquadProcessor()->parameter1()->finalValue();
     54             value2 = biquadProcessor()->parameter2()->finalValue();
     55             gain = biquadProcessor()->parameter3()->finalValue();
     56             detune = biquadProcessor()->parameter4()->finalValue();
     57         } else if (useSmoothing) {
     58             value1 = biquadProcessor()->parameter1()->smoothedValue();
     59             value2 = biquadProcessor()->parameter2()->smoothedValue();
     60             gain = biquadProcessor()->parameter3()->smoothedValue();
     61             detune = biquadProcessor()->parameter4()->smoothedValue();
     62         } else {
     63             value1 = biquadProcessor()->parameter1()->value();
     64             value2 = biquadProcessor()->parameter2()->value();
     65             gain = biquadProcessor()->parameter3()->value();
     66             detune = biquadProcessor()->parameter4()->value();
     67         }
     68 
     69         // Convert from Hertz to normalized frequency 0 -> 1.
     70         double nyquist = this->nyquist();
     71         double normalizedFrequency = value1 / nyquist;
     72 
     73         // Offset frequency by detune.
     74         if (detune)
     75             normalizedFrequency *= pow(2, detune / 1200);
     76 
     77         // Configure the biquad with the new filter parameters for the appropriate type of filter.
     78         switch (biquadProcessor()->type()) {
     79         case BiquadProcessor::LowPass:
     80             m_biquad.setLowpassParams(normalizedFrequency, value2);
     81             break;
     82 
     83         case BiquadProcessor::HighPass:
     84             m_biquad.setHighpassParams(normalizedFrequency, value2);
     85             break;
     86 
     87         case BiquadProcessor::BandPass:
     88             m_biquad.setBandpassParams(normalizedFrequency, value2);
     89             break;
     90 
     91         case BiquadProcessor::LowShelf:
     92             m_biquad.setLowShelfParams(normalizedFrequency, gain);
     93             break;
     94 
     95         case BiquadProcessor::HighShelf:
     96             m_biquad.setHighShelfParams(normalizedFrequency, gain);
     97             break;
     98 
     99         case BiquadProcessor::Peaking:
    100             m_biquad.setPeakingParams(normalizedFrequency, value2, gain);
    101             break;
    102 
    103         case BiquadProcessor::Notch:
    104             m_biquad.setNotchParams(normalizedFrequency, value2);
    105             break;
    106 
    107         case BiquadProcessor::Allpass:
    108             m_biquad.setAllpassParams(normalizedFrequency, value2);
    109             break;
    110         }
    111     }
    112 }
    113 
    114 void BiquadDSPKernel::process(const float* source, float* destination, size_t framesToProcess)
    115 {
    116     ASSERT(source && destination && biquadProcessor());
    117 
    118     // Recompute filter coefficients if any of the parameters have changed.
    119     // FIXME: as an optimization, implement a way that a Biquad object can simply copy its internal filter coefficients from another Biquad object.
    120     // Then re-factor this code to only run for the first BiquadDSPKernel of each BiquadProcessor.
    121 
    122     updateCoefficientsIfNecessary(true, false);
    123 
    124     m_biquad.process(source, destination, framesToProcess);
    125 }
    126 
    127 void BiquadDSPKernel::getFrequencyResponse(int nFrequencies,
    128                                            const float* frequencyHz,
    129                                            float* magResponse,
    130                                            float* phaseResponse)
    131 {
    132     bool isGood = nFrequencies > 0 && frequencyHz && magResponse && phaseResponse;
    133     ASSERT(isGood);
    134     if (!isGood)
    135         return;
    136 
    137     Vector<float> frequency(nFrequencies);
    138 
    139     double nyquist = this->nyquist();
    140 
    141     // Convert from frequency in Hz to normalized frequency (0 -> 1),
    142     // with 1 equal to the Nyquist frequency.
    143     for (int k = 0; k < nFrequencies; ++k)
    144         frequency[k] = narrowPrecisionToFloat(frequencyHz[k] / nyquist);
    145 
    146     // We want to get the final values of the coefficients and compute
    147     // the response from that instead of some intermediate smoothed
    148     // set. Forcefully update the coefficients even if they are not
    149     // dirty.
    150 
    151     updateCoefficientsIfNecessary(false, true);
    152 
    153     m_biquad.getFrequencyResponse(nFrequencies, frequency.data(), magResponse, phaseResponse);
    154 }
    155 
    156 double BiquadDSPKernel::tailTime() const
    157 {
    158     return MaxBiquadDelayTime;
    159 }
    160 
    161 double BiquadDSPKernel::latencyTime() const
    162 {
    163     return 0;
    164 }
    165 
    166 } // namespace WebCore
    167 
    168 #endif // ENABLE(WEB_AUDIO)
    169