| /* |
| * 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. |
| */ |
| |
| #include "platform/audio/Biquad.h" |
| |
| #include "platform/audio/AudioUtilities.h" |
| #include "platform/audio/DenormalDisabler.h" |
| #include "wtf/MathExtras.h" |
| |
| #include <algorithm> |
| #include <complex> |
| #include <stdio.h> |
| #if OS(MACOSX) |
| #include <Accelerate/Accelerate.h> |
| #endif |
| |
| namespace blink { |
| |
| #if OS(MACOSX) |
| const int kBufferSize = 1024; |
| #endif |
| |
| Biquad::Biquad() : m_hasSampleAccurateValues(false) { |
| #if OS(MACOSX) |
| // Allocate two samples more for filter history |
| m_inputBuffer.allocate(kBufferSize + 2); |
| m_outputBuffer.allocate(kBufferSize + 2); |
| #endif |
| |
| // Allocate enough space for the a-rate filter coefficients to handle a |
| // rendering quantum of 128 frames. |
| m_b0.allocate(AudioUtilities::kRenderQuantumFrames); |
| m_b1.allocate(AudioUtilities::kRenderQuantumFrames); |
| m_b2.allocate(AudioUtilities::kRenderQuantumFrames); |
| m_a1.allocate(AudioUtilities::kRenderQuantumFrames); |
| m_a2.allocate(AudioUtilities::kRenderQuantumFrames); |
| |
| // Initialize as pass-thru (straight-wire, no filter effect) |
| setNormalizedCoefficients(0, 1, 0, 0, 1, 0, 0); |
| |
| reset(); // clear filter memory |
| } |
| |
| Biquad::~Biquad() {} |
| |
| void Biquad::process(const float* sourceP, |
| float* destP, |
| size_t framesToProcess) { |
| // WARNING: sourceP and destP may be pointing to the same area of memory! |
| // Be sure to read from sourceP before writing to destP! |
| if (hasSampleAccurateValues()) { |
| int n = framesToProcess; |
| |
| // Create local copies of member variables |
| double x1 = m_x1; |
| double x2 = m_x2; |
| double y1 = m_y1; |
| double y2 = m_y2; |
| |
| const double* b0 = m_b0.data(); |
| const double* b1 = m_b1.data(); |
| const double* b2 = m_b2.data(); |
| const double* a1 = m_a1.data(); |
| const double* a2 = m_a2.data(); |
| |
| for (int k = 0; k < n; ++k) { |
| // FIXME: this can be optimized by pipelining the multiply adds... |
| float x = *sourceP++; |
| float y = b0[k] * x + b1[k] * x1 + b2[k] * x2 - a1[k] * y1 - a2[k] * y2; |
| |
| *destP++ = y; |
| |
| // Update state variables |
| x2 = x1; |
| x1 = x; |
| y2 = y1; |
| y1 = y; |
| } |
| |
| // Local variables back to member. Flush denormals here so we |
| // don't slow down the inner loop above. |
| m_x1 = DenormalDisabler::flushDenormalFloatToZero(x1); |
| m_x2 = DenormalDisabler::flushDenormalFloatToZero(x2); |
| m_y1 = DenormalDisabler::flushDenormalFloatToZero(y1); |
| m_y2 = DenormalDisabler::flushDenormalFloatToZero(y2); |
| |
| // There is an assumption here that once we have sample accurate values we |
| // can never go back to not having sample accurate values. This is |
| // currently true in the way AudioParamTimline is implemented: once an |
| // event is inserted, sample accurate processing is always enabled. |
| // |
| // If so, then we never have to update the state variables for the MACOSX |
| // path. The structure of the state variable in these cases aren't well |
| // documented so it's not clear how to update them anyway. |
| } else { |
| #if OS(MACOSX) |
| double* inputP = m_inputBuffer.data(); |
| double* outputP = m_outputBuffer.data(); |
| |
| // Set up filter state. This is needed in case we're switching from |
| // filtering with variable coefficients (i.e., with automations) to |
| // fixed coefficients (without automations). |
| inputP[0] = m_x2; |
| inputP[1] = m_x1; |
| outputP[0] = m_y2; |
| outputP[1] = m_y1; |
| |
| // Use vecLib if available |
| processFast(sourceP, destP, framesToProcess); |
| |
| // Copy the last inputs and outputs to the filter memory variables. |
| // This is needed because the next rendering quantum might be an |
| // automation which needs the history to continue correctly. Because |
| // sourceP and destP can be the same block of memory, we can't read from |
| // sourceP to get the last inputs. Fortunately, processFast has put the |
| // last inputs in input[0] and input[1]. |
| m_x1 = inputP[1]; |
| m_x2 = inputP[0]; |
| m_y1 = destP[framesToProcess - 1]; |
| m_y2 = destP[framesToProcess - 2]; |
| |
| #else |
| int n = 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[0]; |
| double b1 = m_b1[0]; |
| double b2 = m_b2[0]; |
| double a1 = m_a1[0]; |
| double a2 = m_a2[0]; |
| |
| while (n--) { |
| // FIXME: this can be optimized by pipelining the multiply adds... |
| float x = *sourceP++; |
| float y = b0 * x + b1 * x1 + b2 * x2 - a1 * y1 - a2 * y2; |
| |
| *destP++ = y; |
| |
| // Update state variables |
| x2 = x1; |
| x1 = x; |
| y2 = y1; |
| y1 = y; |
| } |
| |
| // Local variables back to member. Flush denormals here so we |
| // don't slow down the inner loop above. |
| m_x1 = DenormalDisabler::flushDenormalFloatToZero(x1); |
| m_x2 = DenormalDisabler::flushDenormalFloatToZero(x2); |
| m_y1 = DenormalDisabler::flushDenormalFloatToZero(y1); |
| m_y2 = DenormalDisabler::flushDenormalFloatToZero(y2); |
| #endif |
| } |
| } |
| |
| #if OS(MACOSX) |
| |
| // Here we have optimized version using Accelerate.framework |
| |
| void Biquad::processFast(const float* sourceP, |
| float* destP, |
| size_t framesToProcess) { |
| double filterCoefficients[5]; |
| filterCoefficients[0] = m_b0[0]; |
| filterCoefficients[1] = m_b1[0]; |
| filterCoefficients[2] = m_b2[0]; |
| filterCoefficients[3] = m_a1[0]; |
| filterCoefficients[4] = m_a2[0]; |
| |
| double* inputP = m_inputBuffer.data(); |
| double* outputP = m_outputBuffer.data(); |
| |
| double* input2P = inputP + 2; |
| double* output2P = outputP + 2; |
| |
| // Break up processing into smaller slices (kBufferSize) if necessary. |
| |
| int n = framesToProcess; |
| |
| while (n > 0) { |
| int framesThisTime = n < kBufferSize ? n : kBufferSize; |
| |
| // Copy input to input buffer |
| for (int i = 0; i < framesThisTime; ++i) |
| input2P[i] = *sourceP++; |
| |
| processSliceFast(inputP, outputP, filterCoefficients, framesThisTime); |
| |
| // Copy output buffer to output (converts float -> double). |
| for (int i = 0; i < framesThisTime; ++i) |
| *destP++ = static_cast<float>(output2P[i]); |
| |
| n -= framesThisTime; |
| } |
| } |
| |
| void Biquad::processSliceFast(double* sourceP, |
| double* destP, |
| double* coefficientsP, |
| size_t framesToProcess) { |
| // Use double-precision for filter stability |
| vDSP_deq22D(sourceP, 1, coefficientsP, destP, 1, framesToProcess); |
| |
| // Save history. Note that sourceP and destP reference m_inputBuffer and |
| // m_outputBuffer respectively. These buffers are allocated (in the |
| // constructor) with space for two extra samples so it's OK to access array |
| // values two beyond framesToProcess. |
| sourceP[0] = sourceP[framesToProcess - 2 + 2]; |
| sourceP[1] = sourceP[framesToProcess - 1 + 2]; |
| destP[0] = destP[framesToProcess - 2 + 2]; |
| destP[1] = destP[framesToProcess - 1 + 2]; |
| } |
| |
| #endif // OS(MACOSX) |
| |
| void Biquad::reset() { |
| #if OS(MACOSX) |
| // Two extra samples for filter history |
| double* inputP = m_inputBuffer.data(); |
| inputP[0] = 0; |
| inputP[1] = 0; |
| |
| double* outputP = m_outputBuffer.data(); |
| outputP[0] = 0; |
| outputP[1] = 0; |
| |
| #endif |
| m_x1 = m_x2 = m_y1 = m_y2 = 0; |
| } |
| |
| void Biquad::setLowpassParams(int index, double cutoff, double resonance) { |
| // Limit cutoff to 0 to 1. |
| cutoff = clampTo(cutoff, 0.0, 1.0); |
| |
| if (cutoff == 1) { |
| // When cutoff is 1, the z-transform is 1. |
| setNormalizedCoefficients(index, 1, 0, 0, 1, 0, 0); |
| } else if (cutoff > 0) { |
| // Compute biquad coefficients for lowpass filter |
| |
| resonance = pow(10, resonance / 20); |
| double theta = piDouble * cutoff; |
| double alpha = sin(theta) / (2 * resonance); |
| double cosw = cos(theta); |
| double beta = (1 - cosw) / 2; |
| |
| double b0 = beta; |
| double b1 = 2 * beta; |
| double b2 = beta; |
| |
| double a0 = 1 + alpha; |
| double a1 = -2 * cosw; |
| double a2 = 1 - alpha; |
| |
| setNormalizedCoefficients(index, b0, b1, b2, a0, a1, a2); |
| } else { |
| // When cutoff is zero, nothing gets through the filter, so set |
| // coefficients up correctly. |
| setNormalizedCoefficients(index, 0, 0, 0, 1, 0, 0); |
| } |
| } |
| |
| void Biquad::setHighpassParams(int index, double cutoff, double resonance) { |
| // Limit cutoff to 0 to 1. |
| cutoff = clampTo(cutoff, 0.0, 1.0); |
| |
| if (cutoff == 1) { |
| // The z-transform is 0. |
| setNormalizedCoefficients(index, 0, 0, 0, 1, 0, 0); |
| } else if (cutoff > 0) { |
| // Compute biquad coefficients for highpass filter |
| |
| resonance = pow(10, resonance / 20); |
| double theta = piDouble * cutoff; |
| double alpha = sin(theta) / (2 * resonance); |
| double cosw = cos(theta); |
| double beta = (1 + cosw) / 2; |
| |
| double b0 = beta; |
| double b1 = -2 * beta; |
| double b2 = beta; |
| |
| double a0 = 1 + alpha; |
| double a1 = -2 * cosw; |
| double a2 = 1 - alpha; |
| |
| setNormalizedCoefficients(index, b0, b1, b2, a0, 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(index, 1, 0, 0, 1, 0, 0); |
| } |
| } |
| |
| void Biquad::setNormalizedCoefficients(int index, |
| double b0, |
| double b1, |
| double b2, |
| double a0, |
| double a1, |
| double a2) { |
| double a0Inverse = 1 / a0; |
| |
| m_b0[index] = b0 * a0Inverse; |
| m_b1[index] = b1 * a0Inverse; |
| m_b2[index] = b2 * a0Inverse; |
| m_a1[index] = a1 * a0Inverse; |
| m_a2[index] = a2 * a0Inverse; |
| } |
| |
| void Biquad::setLowShelfParams(int index, double frequency, double dbGain) { |
| // Clip frequencies to between 0 and 1, inclusive. |
| frequency = clampTo(frequency, 0.0, 1.0); |
| |
| double A = pow(10.0, dbGain / 40); |
| |
| if (frequency == 1) { |
| // The z-transform is a constant gain. |
| setNormalizedCoefficients(index, A * A, 0, 0, 1, 0, 0); |
| } else if (frequency > 0) { |
| double w0 = piDouble * 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(index, b0, b1, b2, a0, a1, a2); |
| } else { |
| // When frequency is 0, the z-transform is 1. |
| setNormalizedCoefficients(index, 1, 0, 0, 1, 0, 0); |
| } |
| } |
| |
| void Biquad::setHighShelfParams(int index, double frequency, double dbGain) { |
| // Clip frequencies to between 0 and 1, inclusive. |
| frequency = clampTo(frequency, 0.0, 1.0); |
| |
| double A = pow(10.0, dbGain / 40); |
| |
| if (frequency == 1) { |
| // The z-transform is 1. |
| setNormalizedCoefficients(index, 1, 0, 0, 1, 0, 0); |
| } else if (frequency > 0) { |
| double w0 = piDouble * 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(index, b0, b1, b2, a0, a1, a2); |
| } else { |
| // When frequency = 0, the filter is just a gain, A^2. |
| setNormalizedCoefficients(index, A * A, 0, 0, 1, 0, 0); |
| } |
| } |
| |
| void Biquad::setPeakingParams(int index, |
| double frequency, |
| double Q, |
| double dbGain) { |
| // Clip frequencies to between 0 and 1, inclusive. |
| frequency = clampTo(frequency, 0.0, 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 = piDouble * 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(index, 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(index, A * A, 0, 0, 1, 0, 0); |
| } |
| } else { |
| // When frequency is 0 or 1, the z-transform is 1. |
| setNormalizedCoefficients(index, 1, 0, 0, 1, 0, 0); |
| } |
| } |
| |
| void Biquad::setAllpassParams(int index, double frequency, double Q) { |
| // Clip frequencies to between 0 and 1, inclusive. |
| frequency = clampTo(frequency, 0.0, 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 = piDouble * 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(index, 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(index, -1, 0, 0, 1, 0, 0); |
| } |
| } else { |
| // When frequency is 0 or 1, the z-transform is 1. |
| setNormalizedCoefficients(index, 1, 0, 0, 1, 0, 0); |
| } |
| } |
| |
| void Biquad::setNotchParams(int index, double frequency, double Q) { |
| // Clip frequencies to between 0 and 1, inclusive. |
| frequency = clampTo(frequency, 0.0, 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 = piDouble * 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(index, 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(index, 0, 0, 0, 1, 0, 0); |
| } |
| } else { |
| // When frequency is 0 or 1, the z-transform is 1. |
| setNormalizedCoefficients(index, 1, 0, 0, 1, 0, 0); |
| } |
| } |
| |
| void Biquad::setBandpassParams(int index, 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 = piDouble * 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(index, 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(index, 1, 0, 0, 1, 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(index, 0, 0, 0, 1, 0, 0); |
| } |
| } |
| |
| 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[0]; |
| double b1 = m_b1[0]; |
| double b2 = m_b2[0]; |
| double a1 = m_a1[0]; |
| double a2 = m_a2[0]; |
| |
| for (int k = 0; k < nFrequencies; ++k) { |
| double omega = -piDouble * frequency[k]; |
| std::complex<double> z = std::complex<double>(cos(omega), sin(omega)); |
| std::complex<double> numerator = b0 + (b1 + b2 * z) * z; |
| std::complex<double> denominator = |
| std::complex<double>(1, 0) + (a1 + a2 * z) * z; |
| std::complex<double> response = numerator / denominator; |
| magResponse[k] = static_cast<float>(abs(response)); |
| phaseResponse[k] = |
| static_cast<float>(atan2(imag(response), real(response))); |
| } |
| } |
| |
| } // namespace blink |