137 lines
5.6 KiB
C++
137 lines
5.6 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 "IIRFilterNode.h"
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#include "BaseAudioContext.h"
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#include "IIRFilter.h"
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#include "ScriptExecutionContext.h"
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#include <wtf/IsoMallocInlines.h>
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namespace WebCore {
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WTF_MAKE_ISO_ALLOCATED_IMPL(IIRFilterNode);
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// Determine if filter is stable based on the feedback coefficients.
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// We compute the reflection coefficients for the filter. If, at any
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// point, the magnitude of the reflection coefficient is greater than
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// or equal to 1, the filter is declared unstable.
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//
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// Let A(z) be the feedback polynomial given by
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// A[n](z) = 1 + a[1]/z + a[2]/z^2 + ... + a[n]/z^n
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//
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// The first reflection coefficient k[n] = a[n]. Then, recursively compute
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//
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// A[n-1](z) = (A[n](z) - k[n]*A[n](1/z)/z^n)/(1-k[n]^2);
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//
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// stopping at A[1](z). If at any point |k[n]| >= 1, the filter is unstable.
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static bool isFilterStable(const Vector<double>& feedback)
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{
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// Make a copy of the feedback coefficients
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Vector<double> coefficients(feedback);
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int order = coefficients.size() - 1;
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// If necessary, normalize filter coefficients so that constant term is 1.
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if (coefficients[0] != 1) {
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for (int m = 1; m <= order; ++m)
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coefficients[m] /= coefficients[0];
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coefficients[0] = 1;
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}
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// Begin recursion, using a work array to hold intermediate results.
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Vector<double> work(order + 1);
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for (int n = order; n >= 1; --n) {
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double k = coefficients[n];
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if (std::fabs(k) >= 1)
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return false;
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// Note that A[n](1/z)/z^n is basically the coefficients of A[n]
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// in reverse order.
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double factor = 1 - k * k;
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for (int m = 0; m <= n; ++m)
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work[m] = (coefficients[m] - k * coefficients[n - m]) / factor;
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coefficients.swap(work);
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}
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return true;
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}
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ExceptionOr<Ref<IIRFilterNode>> IIRFilterNode::create(ScriptExecutionContext& scriptExecutionContext, BaseAudioContext& context, IIRFilterOptions&& options)
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{
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if (!options.feedforward.size() || options.feedforward.size() > IIRFilter::maxOrder)
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return Exception { NotSupportedError, "feedforward array must have a length between 1 and 20"_s };
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auto nonZeroValueIndex = options.feedforward.findMatching([](auto& value) { return !!value; });
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if (nonZeroValueIndex == notFound)
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return Exception { InvalidStateError, "feedforward array must contain a non-zero value"_s };
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if (!options.feedback.size() || options.feedback.size() > IIRFilter::maxOrder)
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return Exception { NotSupportedError, "feedback array must have a length between 1 and 20"_s };
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if (!options.feedback[0])
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return Exception { InvalidStateError, "first value of feedback array cannot be zero"_s };
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bool isFilterStable = WebCore::isFilterStable(options.feedback);
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if (!isFilterStable)
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scriptExecutionContext.addConsoleMessage(MessageSource::JS, MessageLevel::Warning, "IIRFilter is unstable with provided feedback coefficients"_s);
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auto node = adoptRef(*new IIRFilterNode(context, options.feedforward, options.feedback, isFilterStable));
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auto result = node->handleAudioNodeOptions(options, { 2, ChannelCountMode::Max, ChannelInterpretation::Speakers });
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if (result.hasException())
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return result.releaseException();
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return node;
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}
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IIRFilterNode::IIRFilterNode(BaseAudioContext& context, const Vector<double>& feedforward, const Vector<double>& feedback, bool isFilterStable)
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: AudioBasicProcessorNode(context, NodeTypeIIRFilter)
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{
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m_processor = makeUnique<IIRProcessor>(context.sampleRate(), 1, feedforward, feedback, isFilterStable);
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initialize();
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}
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ExceptionOr<void> IIRFilterNode::getFrequencyResponse(Float32Array& frequencyHz, Float32Array& magResponse, Float32Array& phaseResponse)
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{
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auto expectedLength = frequencyHz.length();
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if (magResponse.length() != expectedLength || phaseResponse.length() != expectedLength)
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return Exception { InvalidAccessError, "Arrays must have the same length"_s };
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// Nothing to do if the length is 0.
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if (expectedLength > 0)
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iirProcessor()->getFrequencyResponse(expectedLength, frequencyHz.data(), magResponse.data(), phaseResponse.data());
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return { };
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}
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} // namespace WebCore
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#endif // ENABLE(WEB_AUDIO)
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