The Tor Browser: content/media/webaudio/blink/Biquad.cpp@6474c204b198 (annotated)

content/media/webaudio/blink/Biquad.cpp@6474c204b198 (annotated)

content/media/webaudio/blink/Biquad.cpp

Wed, 31 Dec 2014 06:09:35 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:09:35 +0100
changeset 0: 6474c204b198
permissions: -rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

 /*
  * 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.
  * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
  *     its contributors may be used to endorse or promote products derived
  *     from this software without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY APPLE 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 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.
  */
 // For M_PI from cmath
 #ifdef _MSC_VER
 #  define _USE_MATH_DEFINES
 #endif
 #include "Biquad.h"
 #include <cmath>
 #include <float.h>
 #include <algorithm>
 namespace WebCore {
 Biquad::Biquad()
 {
     // Initialize as pass-thru (straight-wire, no filter effect)
     setNormalizedCoefficients(1, 0, 0, 1, 0, 0);
     reset(); // clear filter memory
 }
 Biquad::~Biquad()
 {
 }
 void Biquad::process(const float* sourceP, float* destP, size_t framesToProcess)
 {
     // Create local copies of member variables
     double x1 = m_x1;
     double x2 = m_x2;
     double y1 = m_y1;
     double y2 = m_y2;
     double b0 = m_b0;
     double b1 = m_b1;
     double b2 = m_b2;
     double a1 = m_a1;
     double a2 = m_a2;
     for (size_t i = 0; i < framesToProcess; ++i) {
         // FIXME: this can be optimized by pipelining the multiply adds...
         double x = sourceP[i];
         double y = b0*x + b1*x1 + b2*x2 - a1*y1 - a2*y2;
         destP[i] = y;
         // Update state variables
         x2 = x1;
         x1 = x;
         y2 = y1;
         y1 = y;
     }
     // Avoid introducing a stream of subnormals when input is silent and the
     // tail approaches zero.
     if (x1 == 0.0 && x2 == 0.0 && (y1 != 0.0 || y2 != 0.0) &&
         fabs(y1) < FLT_MIN && fabs(y2) < FLT_MIN) {
       // Flush future values to zero (until there is new input).
       y1 = y2 = 0.0;
       // Flush calculated values.
       for (int i = framesToProcess; i-- && fabsf(destP[i]) < FLT_MIN; ) {
         destP[i] = 0.0f;
       }
     }
     // Local variables back to member.
     m_x1 = x1;
     m_x2 = x2;
     m_y1 = y1;
     m_y2 = y2;
 }
 void Biquad::reset()
 {
     m_x1 = m_x2 = m_y1 = m_y2 = 0;
 }
 void Biquad::setLowpassParams(double cutoff, double resonance)
 {
     // Limit cutoff to 0 to 1.
     cutoff = std::max(0.0, std::min(cutoff, 1.0));
     if (cutoff == 1) {
         // When cutoff is 1, the z-transform is 1.
         setNormalizedCoefficients(1, 0, 0,
 , 0, 0);
     } else if (cutoff > 0) {
         // Compute biquad coefficients for lowpass filter
         resonance = std::max(0.0, resonance); // can't go negative
         double g = pow(10.0, 0.05 * resonance);
         double d = sqrt((4 - sqrt(16 - 16 / (g * g))) / 2);
         double theta = M_PI * cutoff;
         double sn = 0.5 * d * sin(theta);
         double beta = 0.5 * (1 - sn) / (1 + sn);
         double gamma = (0.5 + beta) * cos(theta);
         double alpha = 0.25 * (0.5 + beta - gamma);
         double b0 = 2 * alpha;
         double b1 = 2 * 2 * alpha;
         double b2 = 2 * alpha;
         double a1 = 2 * -gamma;
         double a2 = 2 * beta;
         setNormalizedCoefficients(b0, b1, b2, 1, a1, a2);
     } else {
         // When cutoff is zero, nothing gets through the filter, so set
         // coefficients up correctly.
         setNormalizedCoefficients(0, 0, 0,
 , 0, 0);
     }
 }
 void Biquad::setHighpassParams(double cutoff, double resonance)
 {
     // Limit cutoff to 0 to 1.
     cutoff = std::max(0.0, std::min(cutoff, 1.0));
     if (cutoff == 1) {
         // The z-transform is 0.
         setNormalizedCoefficients(0, 0, 0,
 , 0, 0);
     } else if (cutoff > 0) {
         // Compute biquad coefficients for highpass filter
         resonance = std::max(0.0, resonance); // can't go negative
         double g = pow(10.0, 0.05 * resonance);
         double d = sqrt((4 - sqrt(16 - 16 / (g * g))) / 2);
         double theta = M_PI * cutoff;
         double sn = 0.5 * d * sin(theta);
         double beta = 0.5 * (1 - sn) / (1 + sn);
         double gamma = (0.5 + beta) * cos(theta);
         double alpha = 0.25 * (0.5 + beta + gamma);
         double b0 = 2 * alpha;
         double b1 = 2 * -2 * alpha;
         double b2 = 2 * alpha;
         double a1 = 2 * -gamma;
         double a2 = 2 * beta;
         setNormalizedCoefficients(b0, b1, b2, 1, a1, a2);
     } else {
       // When cutoff is zero, we need to be careful because the above
       // gives a quadratic divided by the same quadratic, with poles
       // and zeros on the unit circle in the same place. When cutoff
       // is zero, the z-transform is 1.
         setNormalizedCoefficients(1, 0, 0,
 , 0, 0);
     }
 }
 void Biquad::setNormalizedCoefficients(double b0, double b1, double b2, double a0, double a1, double a2)
 {
     double a0Inverse = 1 / a0;
     m_b0 = b0 * a0Inverse;
     m_b1 = b1 * a0Inverse;
     m_b2 = b2 * a0Inverse;
     m_a1 = a1 * a0Inverse;
     m_a2 = a2 * a0Inverse;
 }
 void Biquad::setLowShelfParams(double frequency, double dbGain)
 {
     // Clip frequencies to between 0 and 1, inclusive.
     frequency = std::max(0.0, std::min(frequency, 1.0));
     double A = pow(10.0, dbGain / 40);
     if (frequency == 1) {
         // The z-transform is a constant gain.
         setNormalizedCoefficients(A * A, 0, 0,
 , 0, 0);
     } else if (frequency > 0) {
         double w0 = M_PI * frequency;
         double S = 1; // filter slope (1 is max value)
         double alpha = 0.5 * sin(w0) * sqrt((A + 1 / A) * (1 / S - 1) + 2);
         double k = cos(w0);
         double k2 = 2 * sqrt(A) * alpha;
         double aPlusOne = A + 1;
         double aMinusOne = A - 1;
         double b0 = A * (aPlusOne - aMinusOne * k + k2);
         double b1 = 2 * A * (aMinusOne - aPlusOne * k);
         double b2 = A * (aPlusOne - aMinusOne * k - k2);
         double a0 = aPlusOne + aMinusOne * k + k2;
         double a1 = -2 * (aMinusOne + aPlusOne * k);
         double a2 = aPlusOne + aMinusOne * k - k2;
         setNormalizedCoefficients(b0, b1, b2, a0, a1, a2);
     } else {
         // When frequency is 0, the z-transform is 1.
         setNormalizedCoefficients(1, 0, 0,
 , 0, 0);
     }
 }
 void Biquad::setHighShelfParams(double frequency, double dbGain)
 {
     // Clip frequencies to between 0 and 1, inclusive.
     frequency = std::max(0.0, std::min(frequency, 1.0));
     double A = pow(10.0, dbGain / 40);
     if (frequency == 1) {
         // The z-transform is 1.
         setNormalizedCoefficients(1, 0, 0,
 , 0, 0);
     } else if (frequency > 0) {
         double w0 = M_PI * frequency;
         double S = 1; // filter slope (1 is max value)
         double alpha = 0.5 * sin(w0) * sqrt((A + 1 / A) * (1 / S - 1) + 2);
         double k = cos(w0);
         double k2 = 2 * sqrt(A) * alpha;
         double aPlusOne = A + 1;
         double aMinusOne = A - 1;
         double b0 = A * (aPlusOne + aMinusOne * k + k2);
         double b1 = -2 * A * (aMinusOne + aPlusOne * k);
         double b2 = A * (aPlusOne + aMinusOne * k - k2);
         double a0 = aPlusOne - aMinusOne * k + k2;
         double a1 = 2 * (aMinusOne - aPlusOne * k);
         double a2 = aPlusOne - aMinusOne * k - k2;
         setNormalizedCoefficients(b0, b1, b2, a0, a1, a2);
     } else {
         // When frequency = 0, the filter is just a gain, A^2.
         setNormalizedCoefficients(A * A, 0, 0,
 , 0, 0);
     }
 }
 void Biquad::setPeakingParams(double frequency, double Q, double dbGain)
 {
     // Clip frequencies to between 0 and 1, inclusive.
     frequency = std::max(0.0, std::min(frequency, 1.0));
     // Don't let Q go negative, which causes an unstable filter.
     Q = std::max(0.0, Q);
     double A = pow(10.0, dbGain / 40);
     if (frequency > 0 && frequency < 1) {
         if (Q > 0) {
             double w0 = M_PI * frequency;
             double alpha = sin(w0) / (2 * Q);
             double k = cos(w0);
             double b0 = 1 + alpha * A;
             double b1 = -2 * k;
             double b2 = 1 - alpha * A;
             double a0 = 1 + alpha / A;
             double a1 = -2 * k;
             double a2 = 1 - alpha / A;
             setNormalizedCoefficients(b0, b1, b2, a0, a1, a2);
         } else {
             // When Q = 0, the above formulas have problems. If we look at
             // the z-transform, we can see that the limit as Q->0 is A^2, so
             // set the filter that way.
             setNormalizedCoefficients(A * A, 0, 0,
 , 0, 0);
         }
     } else {
         // When frequency is 0 or 1, the z-transform is 1.
         setNormalizedCoefficients(1, 0, 0,
 , 0, 0);
     }
 }
 void Biquad::setAllpassParams(double frequency, double Q)
 {
     // Clip frequencies to between 0 and 1, inclusive.
     frequency = std::max(0.0, std::min(frequency, 1.0));
     // Don't let Q go negative, which causes an unstable filter.
     Q = std::max(0.0, Q);
     if (frequency > 0 && frequency < 1) {
         if (Q > 0) {
             double w0 = M_PI * frequency;
             double alpha = sin(w0) / (2 * Q);
             double k = cos(w0);
             double b0 = 1 - alpha;
             double b1 = -2 * k;
             double b2 = 1 + alpha;
             double a0 = 1 + alpha;
             double a1 = -2 * k;
             double a2 = 1 - alpha;
             setNormalizedCoefficients(b0, b1, b2, a0, a1, a2);
         } else {
             // When Q = 0, the above formulas have problems. If we look at
             // the z-transform, we can see that the limit as Q->0 is -1, so
             // set the filter that way.
             setNormalizedCoefficients(-1, 0, 0,
 , 0, 0);
         }
     } else {
         // When frequency is 0 or 1, the z-transform is 1.
         setNormalizedCoefficients(1, 0, 0,
 , 0, 0);
     }
 }
 void Biquad::setNotchParams(double frequency, double Q)
 {
     // Clip frequencies to between 0 and 1, inclusive.
     frequency = std::max(0.0, std::min(frequency, 1.0));
     // Don't let Q go negative, which causes an unstable filter.
     Q = std::max(0.0, Q);
     if (frequency > 0 && frequency < 1) {
         if (Q > 0) {
             double w0 = M_PI * frequency;
             double alpha = sin(w0) / (2 * Q);
             double k = cos(w0);
             double b0 = 1;
             double b1 = -2 * k;
             double b2 = 1;
             double a0 = 1 + alpha;
             double a1 = -2 * k;
             double a2 = 1 - alpha;
             setNormalizedCoefficients(b0, b1, b2, a0, a1, a2);
         } else {
             // When Q = 0, the above formulas have problems. If we look at
             // the z-transform, we can see that the limit as Q->0 is 0, so
             // set the filter that way.
             setNormalizedCoefficients(0, 0, 0,
 , 0, 0);
         }
     } else {
         // When frequency is 0 or 1, the z-transform is 1.
         setNormalizedCoefficients(1, 0, 0,
 , 0, 0);
     }
 }
 void Biquad::setBandpassParams(double frequency, double Q)
 {
     // No negative frequencies allowed.
     frequency = std::max(0.0, frequency);
     // Don't let Q go negative, which causes an unstable filter.
     Q = std::max(0.0, Q);
     if (frequency > 0 && frequency < 1) {
         double w0 = M_PI * frequency;
         if (Q > 0) {
             double alpha = sin(w0) / (2 * Q);
             double k = cos(w0);
             double b0 = alpha;
             double b1 = 0;
             double b2 = -alpha;
             double a0 = 1 + alpha;
             double a1 = -2 * k;
             double a2 = 1 - alpha;
             setNormalizedCoefficients(b0, b1, b2, a0, a1, a2);
         } else {
             // When Q = 0, the above formulas have problems. If we look at
             // the z-transform, we can see that the limit as Q->0 is 1, so
             // set the filter that way.
             setNormalizedCoefficients(1, 0, 0,
 , 0, 0);
         }
     } else {
         // When the cutoff is zero, the z-transform approaches 0, if Q
         // > 0. When both Q and cutoff are zero, the z-transform is
         // pretty much undefined. What should we do in this case?
         // For now, just make the filter 0. When the cutoff is 1, the
         // z-transform also approaches 0.
         setNormalizedCoefficients(0, 0, 0,
 , 0, 0);
     }
 }
 void Biquad::setZeroPolePairs(const Complex &zero, const Complex &pole)
 {
     double b0 = 1;
     double b1 = -2 * zero.real();
     double zeroMag = abs(zero);
     double b2 = zeroMag * zeroMag;
     double a1 = -2 * pole.real();
     double poleMag = abs(pole);
     double a2 = poleMag * poleMag;
     setNormalizedCoefficients(b0, b1, b2, 1, a1, a2);
 }
 void Biquad::setAllpassPole(const Complex &pole)
 {
     Complex zero = Complex(1, 0) / pole;
     setZeroPolePairs(zero, pole);
 }
 void Biquad::getFrequencyResponse(int nFrequencies,
                                   const float* frequency,
                                   float* magResponse,
                                   float* phaseResponse)
 {
     // Evaluate the Z-transform of the filter at given normalized
     // frequency from 0 to 1.  (1 corresponds to the Nyquist
     // frequency.)
     //
     // The z-transform of the filter is
     //
     // H(z) = (b0 + b1*z^(-1) + b2*z^(-2))/(1 + a1*z^(-1) + a2*z^(-2))
     //
     // Evaluate as
     //
     // b0 + (b1 + b2*z1)*z1
     // --------------------
     // 1 + (a1 + a2*z1)*z1
     //
     // with z1 = 1/z and z = exp(j*pi*frequency). Hence z1 = exp(-j*pi*frequency)
     // Make local copies of the coefficients as a micro-optimization.
     double b0 = m_b0;
     double b1 = m_b1;
     double b2 = m_b2;
     double a1 = m_a1;
     double a2 = m_a2;
     for (int k = 0; k < nFrequencies; ++k) {
         double omega = -M_PI * frequency[k];
         Complex z = Complex(cos(omega), sin(omega));
         Complex numerator = b0 + (b1 + b2 * z) * z;
         Complex denominator = Complex(1, 0) + (a1 + a2 * z) * z;
         Complex response = numerator / denominator;
         magResponse[k] = static_cast<float>(abs(response));
         phaseResponse[k] = static_cast<float>(atan2(imag(response), real(response)));
     }
 }
 } // namespace WebCore

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content/media/webaudio/blink/Biquad.cpp@6474c204b198 (annotated)

content/media/webaudio/blink/Biquad.cpp