Android Open Source - voicesmith Vad Processor

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From Project

Back to project page voicesmith.

License

The source code is released under:

GNU General Public License

Java Source Code

/*
 * Voicesmith <http://voicesmith.jurihock.de/>
 */*  ww  w  .j a  v a2s. co  m*/
 * Copyright (c) 2011-2014 Juergen Hock
 *
 * This program 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.
 *
 * This program 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 program.  If not, see <http://www.gnu.org/licenses/>.
 */

package de.jurihock.voicesmith.dsp.processors;

import android.content.Context;
import de.jurihock.voicesmith.Preferences;
import de.jurihock.voicesmith.Utils;
import de.jurihock.voicesmith.dsp.LuenbergerObserver;
import de.jurihock.voicesmith.dsp.SchmittTrigger;

import static de.jurihock.voicesmith.dsp.Math.ceil;
import static de.jurihock.voicesmith.dsp.Math.rms;
import static de.jurihock.voicesmith.dsp.Math.min;
import static de.jurihock.voicesmith.dsp.Math.rms2dbfs;
import static de.jurihock.voicesmith.dsp.Math.round;

public final class VadProcessor
{
    private final int sampleRate;

  private final float windowTimeInterval = 20e-3F;
  private final int windowSize;

  private final float[] energyObserverGain = new float[] {0.3F, 0.02F};

  private final LuenbergerObserver energyObserver;
  private final SchmittTrigger trigger;

    private final float hangoverMaxDuration;
    private float hangoverDuration;

    private final boolean isEnabled;

    // Special variables for debugging
    private Utils utils = null;
    private boolean lastState = false;

    public VadProcessor(int sampleRate, Context context)
    {
        this(sampleRate,
            new Preferences(context).getAutoMuteHighThreshold(),
            new Preferences(context).getAutoMuteLowThreshold(),
            new Preferences(context).getAutoMuteHangover(),
            new Preferences(context).isAutoMuteOn());

        if(new Preferences(context).isLoggingOn())
            utils = new Utils(context);
    }

  public VadProcessor(int sampleRate, int lowThreshold, int highThreshold, int hangover, boolean enable)
  {
        this.sampleRate = sampleRate;

    windowSize = round(sampleRate * windowTimeInterval);
        if (utils != null) utils.log("VAD desired window size is %s.", windowSize);

    final float initialDbfs = (lowThreshold + highThreshold) / 2F;

    energyObserver = new LuenbergerObserver(initialDbfs, 0, energyObserverGain);
    trigger = new SchmittTrigger(false, initialDbfs, lowThreshold, highThreshold);

        hangoverMaxDuration = hangover;
        hangoverDuration = 0;

        isEnabled = enable;
  }

  public void processFrame(short[] frame)
  {
        if(!isEnabled) return;

    final int windowCount = frame.length / windowSize;
    final int adaptedWindowSize = windowCount > 0
                ? (int)ceil((float)frame.length / (float)windowCount) // round up division result, if numbers are odd
                : frame.length; // if the window is smaller than frame, so make it just bigger
        final float windowDuration = (float)adaptedWindowSize / (float)sampleRate;

    for (int i = 0; i < windowCount; i++)
    {
      final int windowOffset = i * adaptedWindowSize;
      processFrameInternal(frame, windowOffset, adaptedWindowSize, windowDuration);
    }
  }

  private void processFrameInternal(short[] frame, int offset, int length, float windowDuration)
  {
    float currentRms = rms(frame, offset, length);
    float currentDbfs = rms2dbfs(currentRms, 1e-10F, 1F);

    currentDbfs = energyObserver.smooth(currentDbfs);
    boolean currentState = trigger.state(currentDbfs);

        if(hangoverMaxDuration > 0)
        {
            if(!currentState)
            {
                hangoverDuration = min(hangoverMaxDuration, hangoverDuration + windowDuration);
                currentState = hangoverDuration < hangoverMaxDuration;
            }
            else
            {
                hangoverDuration = 0;
            }
        }

    if(!currentState)
        {
            for (int i = offset; i < offset + length; i++)
            {
                frame[i] = 0;
            }
        }

        // Log state changes
        if (utils != null && lastState != currentState)
        {
            if (currentState) utils.log("Voice activity detected.");
            else utils.log("Voice inactivity detected.");
            lastState = currentState;
        }
  }
}

Java Source Code List

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