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/*
==============================================================================
This file is part of the IEM plug-in suite.
Author: Daniel Rudrich
Copyright (c) 2017 - Institute of Electronic Music and Acoustics (IEM)
https://iem.at
The IEM plug-in suite is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
The IEM plug-in suite is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this software. If not, see <https://www.gnu.org/licenses/>.
==============================================================================
*/
#pragma once
#include <JuceHeader.h>
namespace iem
{
class Compressor
{
public:
Compressor() {}
~Compressor() {}
void prepare (const juce::dsp::ProcessSpec spec)
{
sampleRate = spec.sampleRate;
alphaAttack = 1.0 - timeToGain (attackTime);
alphaRelease = 1.0 - timeToGain (releaseTime);
prepared = true;
}
void setAttackTime (float attackTimeInSeconds)
{
attackTime = attackTimeInSeconds;
alphaAttack = 1.0 - timeToGain (attackTime);
}
void setReleaseTime (float releaseTimeInSeconds)
{
releaseTime = releaseTimeInSeconds;
alphaRelease = 1.0 - timeToGain (releaseTime);
}
double timeToGain (float timeInSeconds) { return exp (-1.0 / (sampleRate * timeInSeconds)); }
void setKnee (float kneeInDecibels)
{
knee = kneeInDecibels;
kneeHalf = knee / 2.0f;
}
const float getKnee() { return knee; }
void setThreshold (float thresholdInDecibels) { threshold = thresholdInDecibels; }
const float getTreshold() { return threshold; }
void setMakeUpGain (float makeUpGainInDecibels) { makeUpGain = makeUpGainInDecibels; }
const float getMakeUpGain() { return makeUpGain; }
void setRatio (float ratio) { slope = 1.0f / ratio - 1.0f; }
const float getMaxLevelInDecibels() { return maxLevel; }
void applyCharacteristicToOverShoot (float& overShoot)
{
if (overShoot <= -kneeHalf)
overShoot = 0.0f; //y_G = levelInDecibels;
else if (overShoot > -kneeHalf && overShoot <= kneeHalf)
overShoot =
0.5f * slope * juce::square (overShoot + kneeHalf)
/ knee; //y_G = levelInDecibels + 0.5f * slope * square(overShoot + kneeHalf) / knee;
else
overShoot = slope * overShoot;
}
void getGainFromSidechainSignal (const float* sideChainSignal,
float* destination,
const int numSamples)
{
maxLevel = -INFINITY;
for (int i = 0; i < numSamples; ++i)
{
// convert sample to decibels
float levelInDecibels = juce::Decibels::gainToDecibels (abs (sideChainSignal[i]));
if (levelInDecibels > maxLevel)
maxLevel = levelInDecibels;
// calculate overshoot and apply knee and ratio
float overShoot = levelInDecibels - threshold;
applyCharacteristicToOverShoot (overShoot); //y_G = levelInDecibels + slope * overShoot;
// ballistics
const float diff = overShoot - state;
if (diff < 0.0f)
state += alphaAttack * diff;
else
state += alphaRelease * diff;
destination[i] = juce::Decibels::decibelsToGain (state + makeUpGain);
}
}
void getGainFromSidechainSignalInDecibelsWithoutMakeUpGain (const float* sideChainSignal,
float* destination,
const int numSamples)
{
maxLevel = -INFINITY;
for (int i = 0; i < numSamples; ++i)
{
// convert sample to decibels
float levelInDecibels = juce::Decibels::gainToDecibels (abs (sideChainSignal[i]));
if (levelInDecibels > maxLevel)
maxLevel = levelInDecibels;
// calculate overshoot and apply knee and ratio
float overShoot = levelInDecibels - threshold;
applyCharacteristicToOverShoot (overShoot); //y_G = levelInDecibels + slope * overShoot;
// ballistics
const float diff = overShoot - state;
if (diff < 0.0f)
state += alphaAttack * diff;
else
state += alphaRelease * diff;
destination[i] = state;
}
}
void getCharacteristic (float* inputLevels, float* dest, const int numSamples)
{
for (int i = 0; i < numSamples; ++i)
{
dest[i] = getCharacteristicSample (inputLevels[i]);
}
}
inline float getCharacteristicSample (float inputLevel)
{
float overShoot = inputLevel - threshold;
applyCharacteristicToOverShoot (overShoot);
return overShoot + inputLevel + makeUpGain;
}
private:
double sampleRate { 0.0 };
bool prepared;
float knee { 0.0f }, kneeHalf { 0.0f };
float threshold { -10.0f };
float attackTime { 0.01f };
float releaseTime { 0.15f };
float slope { 0.0f };
float makeUpGain { 0.0f };
float maxLevel { -INFINITY };
//state juce::variable
float state { 0.0f };
double alphaAttack;
double alphaRelease;
};
} // namespace iem
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