package com.nerdscentral.audio.volume;
import java.util.List;
import com.nerdscentral.audio.core.SFConstants;
import com.nerdscentral.audio.core.SFSignal;
import com.nerdscentral.sython.Caster;
import com.nerdscentral.sython.SFMaths;
import com.nerdscentral.sython.SFPL_Operator;
import com.nerdscentral.sython.SFPL_RuntimeException;
public class SF_Follow implements SFPL_Operator
{
private static final long serialVersionUID = 1L;
class Follower
{
private final double attack_coef;
private final double release_coef;
private double envelope;
Follower(double attack, double release)
{
attack_coef = Math.exp(Math.log(0.01) / (attack * SFConstants.SAMPLE_RATE * 0.001));
release_coef = Math.exp(Math.log(0.01) / (release * SFConstants.SAMPLE_RATE * 0.001));
envelope = 0.0;
}
double step(double in)
{
double tmp = SFMaths.abs(in);
if (tmp > envelope) envelope = attack_coef * (envelope - tmp) + tmp;
else
envelope = release_coef * (envelope - tmp) + tmp;
return envelope;
}
}
@Override
public String Word()
{
return Messages.getString("SF_Follow.0"); //$NON-NLS-1$
}
@Override
public Object Interpret(Object input) throws SFPL_RuntimeException
{
List<Object> lin = Caster.makeBunch(input);
double attack = Caster.makeDouble(lin.get(1));
double release = Caster.makeDouble(lin.get(2));
SFSignal signal = Caster.makeSFSignal(lin.get(0));
Follower fol = new Follower(attack, release);
SFSignal ret = signal.replicateEmpty();
for (int index = 0; index < signal.getLength(); ++index)
{
ret.setSample(index, fol.step(signal.getSample(index)));
}
return ret;
}
}