106 lines
3.9 KiB
C++
106 lines
3.9 KiB
C++
/*
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* Copyright 2016 The Chromium Authors. All rights reserved.
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* Copyright (C) 2020, Apple Inc. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' AND ANY
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* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS BE LIABLE FOR ANY
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* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
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* ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "config.h"
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#if ENABLE(WEB_AUDIO)
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#include "IIRProcessor.h"
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#include "IIRDSPKernel.h"
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namespace WebCore {
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IIRProcessor::IIRProcessor(float sampleRate, unsigned numberOfChannels, const Vector<double>& feedforward, const Vector<double>& feedback, bool isFilterStable)
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: AudioDSPKernelProcessor(sampleRate, numberOfChannels)
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, m_feedforward(feedforward)
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, m_feedback(feedback)
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, m_isFilterStable(isFilterStable)
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{
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unsigned feedbackLength = feedback.size();
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unsigned feedforwardLength = feedforward.size();
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ASSERT(feedbackLength > 0);
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ASSERT(feedforwardLength > 0);
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// Need to scale the feedback and feedforward coefficients appropriately.
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// (It's up to the caller to ensure feedbackCoef[0] is not 0.)
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ASSERT(!!feedback[0]);
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if (feedback[0] != 1) {
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// The provided filter is:
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//
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// a[0]*y(n) + a[1]*y(n-1) + ... = b[0]*x(n) + b[1]*x(n-1) + ...
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//
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// We want the leading coefficient of y(n) to be 1:
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//
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// y(n) + a[1]/a[0]*y(n-1) + ... = b[0]/a[0]*x(n) + b[1]/a[0]*x(n-1) + ...
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//
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// Thus, the feedback and feedforward coefficients need to be scaled by 1/a[0].
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float scale = feedback[0];
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for (unsigned k = 1; k < feedbackLength; ++k)
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m_feedback[k] /= scale;
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for (unsigned k = 0; k < feedforwardLength; ++k)
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m_feedforward[k] /= scale;
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// The IIRFilter checks to make sure this coefficient is 1, so make it so.
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m_feedback[0] = 1;
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}
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m_responseKernel = makeUnique<IIRDSPKernel>(*this);
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}
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IIRProcessor::~IIRProcessor()
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{
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if (isInitialized())
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uninitialize();
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}
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std::unique_ptr<AudioDSPKernel> IIRProcessor::createKernel()
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{
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return makeUnique<IIRDSPKernel>(*this);
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}
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void IIRProcessor::process(const AudioBus* source, AudioBus* destination, size_t framesToProcess)
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{
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if (!isInitialized()) {
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destination->zero();
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return;
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}
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// For each channel of our input, process using the corresponding IIRDSPKernel
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// into the output channel.
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for (size_t i = 0; i < m_kernels.size(); ++i)
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m_kernels[i]->process(source->channel(i)->data(), destination->channel(i)->mutableData(), framesToProcess);
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}
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void IIRProcessor::getFrequencyResponse(unsigned length, const float* frequencyHz, float* magResponse, float* phaseResponse)
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{
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m_responseKernel->getFrequencyResponse(length, frequencyHz, magResponse, phaseResponse);
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}
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} // namespace WebCore
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#endif // ENABLE(WEB_AUDIO)
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