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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 #ifndef BiquadDSPKernel_h
     26 #define BiquadDSPKernel_h
     27 
     28 #include "platform/audio/AudioDSPKernel.h"
     29 #include "platform/audio/Biquad.h"
     30 #include "modules/webaudio/BiquadProcessor.h"
     31 
     32 namespace WebCore {
     33 
     34 class BiquadProcessor;
     35 
     36 // BiquadDSPKernel is an AudioDSPKernel and is responsible for filtering one channel of a BiquadProcessor using a Biquad object.
     37 
     38 class BiquadDSPKernel FINAL : public AudioDSPKernel {
     39 public:
     40     explicit BiquadDSPKernel(BiquadProcessor* processor)
     41     : AudioDSPKernel(processor)
     42     {
     43     }
     44 
     45     // AudioDSPKernel
     46     virtual void process(const float* source, float* dest, size_t framesToProcess) OVERRIDE;
     47     virtual void reset() OVERRIDE { m_biquad.reset(); }
     48 
     49     // Get the magnitude and phase response of the filter at the given
     50     // set of frequencies (in Hz). The phase response is in radians.
     51     void getFrequencyResponse(int nFrequencies,
     52                               const float* frequencyHz,
     53                               float* magResponse,
     54                               float* phaseResponse);
     55 
     56     virtual double tailTime() const OVERRIDE;
     57     virtual double latencyTime() const OVERRIDE;
     58 
     59 protected:
     60     Biquad m_biquad;
     61     BiquadProcessor* biquadProcessor() { return static_cast<BiquadProcessor*>(processor()); }
     62 
     63     // To prevent audio glitches when parameters are changed,
     64     // dezippering is used to slowly change the parameters.
     65     void updateCoefficientsIfNecessary();
     66     // Update the biquad cofficients with the given parameters
     67     void updateCoefficients(double frequency, double Q, double gain, double detune);
     68 
     69 private:
     70     // Synchronize process() with getting and setting the filter coefficients.
     71     mutable Mutex m_processLock;
     72 };
     73 
     74 } // namespace WebCore
     75 
     76 #endif // BiquadDSPKernel_h
     77