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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  *
      8  * 1.  Redistributions of source code must retain the above copyright
      9  *     notice, this list of conditions and the following disclaimer.
     10  * 2.  Redistributions in binary form must reproduce the above copyright
     11  *     notice, this list of conditions and the following disclaimer in the
     12  *     documentation and/or other materials provided with the distribution.
     13  * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
     14  *     its contributors may be used to endorse or promote products derived
     15  *     from this software without specific prior written permission.
     16  *
     17  * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
     18  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
     19  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
     20  * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
     21  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
     22  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
     23  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
     24  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     26  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     27  */
     28 
     29 #ifndef Biquad_h
     30 #define Biquad_h
     31 
     32 #include <sys/types.h>
     33 #include "core/platform/audio/AudioArray.h"
     34 #include "wtf/Complex.h"
     35 
     36 #if USE(WEBAUDIO_IPP)
     37 #include <ipps.h>
     38 #endif // USE(WEBAUDIO_IPP)
     39 
     40 namespace WebCore {
     41 
     42 // A basic biquad (two-zero / two-pole digital filter)
     43 //
     44 // It can be configured to a number of common and very useful filters:
     45 //    lowpass, highpass, shelving, parameteric, notch, allpass, ...
     46 
     47 class Biquad {
     48 public:
     49     Biquad();
     50     virtual ~Biquad();
     51 
     52     void process(const float* sourceP, float* destP, size_t framesToProcess);
     53 
     54     // frequency is 0 - 1 normalized, resonance and dbGain are in decibels.
     55     // Q is a unitless quality factor.
     56     void setLowpassParams(double frequency, double resonance);
     57     void setHighpassParams(double frequency, double resonance);
     58     void setBandpassParams(double frequency, double Q);
     59     void setLowShelfParams(double frequency, double dbGain);
     60     void setHighShelfParams(double frequency, double dbGain);
     61     void setPeakingParams(double frequency, double Q, double dbGain);
     62     void setAllpassParams(double frequency, double Q);
     63     void setNotchParams(double frequency, double Q);
     64 
     65     // Set the biquad coefficients given a single zero (other zero will be conjugate)
     66     // and a single pole (other pole will be conjugate)
     67     void setZeroPolePairs(const Complex& zero, const Complex& pole);
     68 
     69     // Set the biquad coefficients given a single pole (other pole will be conjugate)
     70     // (The zeroes will be the inverse of the poles)
     71     void setAllpassPole(const Complex& pole);
     72 
     73     // Resets filter state
     74     void reset();
     75 
     76     // Filter response at a set of n frequencies. The magnitude and
     77     // phase response are returned in magResponse and phaseResponse.
     78     // The phase response is in radians.
     79     void getFrequencyResponse(int nFrequencies,
     80                               const float* frequency,
     81                               float* magResponse,
     82                               float* phaseResponse);
     83 private:
     84     void setNormalizedCoefficients(double b0, double b1, double b2, double a0, double a1, double a2);
     85 
     86     // Filter coefficients. The filter is defined as
     87     //
     88     // y[n] + m_a1*y[n-1] + m_a2*y[n-2] = m_b0*x[n] + m_b1*x[n-1] + m_b2*x[n-2].
     89     double m_b0;
     90     double m_b1;
     91     double m_b2;
     92     double m_a1;
     93     double m_a2;
     94 
     95 #if OS(DARWIN)
     96     void processFast(const float* sourceP, float* destP, size_t framesToProcess);
     97     void processSliceFast(double* sourceP, double* destP, double* coefficientsP, size_t framesToProcess);
     98 
     99     AudioDoubleArray m_inputBuffer;
    100     AudioDoubleArray m_outputBuffer;
    101 
    102 #elif USE(WEBAUDIO_IPP)
    103     IppsIIRState64f_32f* m_biquadState;
    104     Ipp8u* m_ippInternalBuffer;
    105 
    106 #else
    107     // Filter memory
    108     double m_x1; // input delayed by 1 sample
    109     double m_x2; // input delayed by 2 samples
    110     double m_y1; // output delayed by 1 sample
    111     double m_y2; // output delayed by 2 samples
    112 #endif
    113 };
    114 
    115 } // namespace WebCore
    116 
    117 #endif // Biquad_h
    118