JUCE/modules/juce_dsp/widgets/juce_NoiseGate.cpp

/*
  ==============================================================================

   This file is part of the JUCE 6 technical preview.
   Copyright (c) 2020 - Raw Material Software Limited

   You may use this code under the terms of the GPL v3
   (see www.gnu.org/licenses).

   For this technical preview, this file is not subject to commercial licensing.

   JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
   EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
   DISCLAIMED.

  ==============================================================================
*/

namespace juce
{
namespace dsp
{

//==============================================================================
template <typename SampleType>
NoiseGate<SampleType>::NoiseGate()
{
    update();

    RMSFilter.setLevelCalculationType (BallisticsFilterLevelCalculationType::RMS);
    RMSFilter.setAttackTime  (static_cast<SampleType> (0.0));
    RMSFilter.setReleaseTime (static_cast<SampleType> (50.0));
}

template <typename SampleType>
void NoiseGate<SampleType>::setThreshold (SampleType newValue)
{
    thresholddB = newValue;
    update();
}

template <typename SampleType>
void NoiseGate<SampleType>::setRatio (SampleType newRatio)
{
    jassert (newRatio >= static_cast<SampleType> (1.0));

    ratio = newRatio;
    update();
}

template <typename SampleType>
void NoiseGate<SampleType>::setAttack (SampleType newAttack)
{
    attackTime = newAttack;
    update();
}

template <typename SampleType>
void NoiseGate<SampleType>::setRelease (SampleType newRelease)
{
    releaseTime = newRelease;
    update();
}

//==============================================================================
template <typename SampleType>
void NoiseGate<SampleType>::prepare (const ProcessSpec& spec)
{
    jassert (spec.sampleRate > 0);
    jassert (spec.numChannels > 0);

    sampleRate = spec.sampleRate;

    RMSFilter.prepare (spec);
    envelopeFilter.prepare (spec);

    update();
    reset();
}

template <typename SampleType>
void NoiseGate<SampleType>::reset()
{
    RMSFilter.reset();
    envelopeFilter.reset();
}

//==============================================================================
template <typename SampleType>
SampleType NoiseGate<SampleType>::processSample (int channel, SampleType sample)
{
    // RMS ballistics filter
    auto env = RMSFilter.processSample (channel, sample);

    // Ballistics filter
    env = envelopeFilter.processSample (channel, env);

    // VCA
    auto gain = (env > threshold) ? static_cast<SampleType> (1.0)
                                  : std::pow (env * thresholdInverse, currentRatio - static_cast<SampleType> (1.0));

    // Output
    return gain * sample;
}

template <typename SampleType>
void NoiseGate<SampleType>::update()
{
    threshold = Decibels::decibelsToGain (thresholddB, static_cast<SampleType> (-200.0));
    thresholdInverse = static_cast<SampleType> (1.0) / threshold;
    currentRatio = ratio;

    envelopeFilter.setAttackTime  (attackTime);
    envelopeFilter.setReleaseTime (releaseTime);
}

//==============================================================================
template class NoiseGate<float>;
template class NoiseGate<double>;

} // namespace dsp
} // namespace juce