third_party/WebKit/Source/modules/webaudio/BiquadProcessor.cpp

/*
 * Copyright (C) 2010, Google Inc. All rights reserved.
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 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
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 *    notice, this list of conditions and the following disclaimer in the
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 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' AND
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 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS BE LIABLE
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 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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#include "modules/webaudio/BiquadDSPKernel.h"
#include "modules/webaudio/BiquadProcessor.h"
#include "wtf/PtrUtil.h"
#include <memory>

namespace blink {

BiquadProcessor::BiquadProcessor(float sampleRate,
                                 size_t numberOfChannels,
                                 AudioParamHandler& frequency,
                                 AudioParamHandler& q,
                                 AudioParamHandler& gain,
                                 AudioParamHandler& detune)
    : AudioDSPKernelProcessor(sampleRate, numberOfChannels),
      m_type(LowPass),
      m_parameter1(frequency),
      m_parameter2(q),
      m_parameter3(gain),
      m_parameter4(detune),
      m_filterCoefficientsDirty(true),
      m_hasSampleAccurateValues(false) {}

BiquadProcessor::~BiquadProcessor() {
  if (isInitialized())
    uninitialize();
}

std::unique_ptr<AudioDSPKernel> BiquadProcessor::createKernel() {
  return wrapUnique(new BiquadDSPKernel(this));
}

void BiquadProcessor::checkForDirtyCoefficients() {
  // Deal with smoothing / de-zippering. Start out assuming filter parameters
  // are not changing.

  // The BiquadDSPKernel objects rely on this value to see if they need to
  // re-compute their internal filter coefficients.
  m_filterCoefficientsDirty = false;
  m_hasSampleAccurateValues = false;

  if (m_parameter1->hasSampleAccurateValues() ||
      m_parameter2->hasSampleAccurateValues() ||
      m_parameter3->hasSampleAccurateValues() ||
      m_parameter4->hasSampleAccurateValues()) {
    m_filterCoefficientsDirty = true;
    m_hasSampleAccurateValues = true;
  } else {
    if (m_hasJustReset) {
      // Snap to exact values first time after reset, then smooth for subsequent
      // changes.
      m_parameter1->resetSmoothedValue();
      m_parameter2->resetSmoothedValue();
      m_parameter3->resetSmoothedValue();
      m_parameter4->resetSmoothedValue();
      m_filterCoefficientsDirty = true;
      m_hasJustReset = false;
    } else {
      // Smooth all of the filter parameters. If they haven't yet converged to
      // their target value then mark coefficients as dirty.
      bool isStable1 = m_parameter1->smooth();
      bool isStable2 = m_parameter2->smooth();
      bool isStable3 = m_parameter3->smooth();
      bool isStable4 = m_parameter4->smooth();
      if (!(isStable1 && isStable2 && isStable3 && isStable4))
        m_filterCoefficientsDirty = true;
    }
  }
}

void BiquadProcessor::process(const AudioBus* source,
                              AudioBus* destination,
                              size_t framesToProcess) {
  if (!isInitialized()) {
    destination->zero();
    return;
  }

  // Synchronize with possible dynamic changes to the impulse response.
  MutexTryLocker tryLocker(m_processLock);
  if (!tryLocker.locked()) {
    // Can't get the lock. We must be in the middle of changing something.
    destination->zero();
    return;
  }

  checkForDirtyCoefficients();

  // For each channel of our input, process using the corresponding
  // BiquadDSPKernel into the output channel.
  for (unsigned i = 0; i < m_kernels.size(); ++i)
    m_kernels[i]->process(source->channel(i)->data(),
                          destination->channel(i)->mutableData(),
                          framesToProcess);
}

void BiquadProcessor::setType(FilterType type) {
  if (type != m_type) {
    m_type = type;
    reset();  // The filter state must be reset only if the type has changed.
  }
}

void BiquadProcessor::getFrequencyResponse(int nFrequencies,
                                           const float* frequencyHz,
                                           float* magResponse,
                                           float* phaseResponse) {
  // Compute the frequency response on a separate temporary kernel
  // to avoid interfering with the processing running in the audio
  // thread on the main kernels.

  std::unique_ptr<BiquadDSPKernel> responseKernel =
      wrapUnique(new BiquadDSPKernel(this));
  responseKernel->getFrequencyResponse(nFrequencies, frequencyHz, magResponse,
                                       phaseResponse);
}

}  // namespace blink