SF_TruncateSilence.java

package com.nerdscentral.audio.time;

import java.util.LinkedList;
import java.util.List;

import com.nerdscentral.audio.core.SFConstants;
import com.nerdscentral.audio.core.SFData;
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_TruncateSilence implements SFPL_Operator
{

    private static final long serialVersionUID = 1L;

    @Override
    public String Word()
    {
        return Messages.getString("SF_TruncateSilence.0"); //$NON-NLS-1$
    }

    @Override
    public Object Interpret(Object input) throws SFPL_RuntimeException
    {
        List<Object> lin = Caster.makeBunch(input);
        SFSignal data = Caster.makeSFSignal(lin.get(0));
        double threshold = SFConstants.fromDBs(Caster.makeDouble(lin.get(1)));
        int len = (int) (Caster.makeDouble(lin.get(2)) * SFConstants.SAMPLE_RATE_MS);
        int newlen = 0;
        if (lin.size() > 3)
        {
            newlen = (int) Caster.makeDouble(lin.get(3));
        }
        int inLen = data.getLength();
        List<double[]> segments = new LinkedList<>();
        int outLen = 0;
        boolean inSilence = false;
        for (int index = 0; index < inLen;)
        {
            int diff = inLen - index;
            diff = diff > len ? len : diff;
            double[] segment = new double[diff];
            double max = 0;
            for (int inner = 0; inner < diff;)
            {
                double x;
                segment[inner] = x = data.getSample(index);
                x = SFMaths.abs(x);
                if (x > max) max = x;
                ++inner;
                ++index;
            }
            if (max > threshold)
            {
                segments.add(segment);
                inSilence = false;
            }
            else
            {
                if (newlen > 0 && !inSilence)
                {
                    segments.add(new double[(int) (newlen * SFConstants.SAMPLE_RATE_MS)]);
                    inSilence = true;
                }
            }
            outLen += segment.length;
        }
        SFSignal outData = SFData.build(outLen);
        int index = 0;
        for (double[] segment : segments)
        {
            for (int inner = 0; inner < segment.length;)
            {
                outData.setSample(index, segment[inner]);
                ++index;
                ++inner;
            }
        }

        return outData;

    }
}