Android Open Source - Backyard-Brains-Android-App Trigger Averager

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License

The source code is released under:

GNU General Public License

Java Source Code

/*
 * Backyard Brains Android App//from   w w w.  j a  va2  s.c o  m
 * Copyright (C) 2011 Backyard Brains
 * by Nathan Dotz <nate (at) backyardbrains.com>
 *
 * 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 com.backyardbrains.audio;

import java.nio.ByteBuffer;
import java.nio.ShortBuffer;
import java.util.ArrayList;

import android.os.Handler;

public class TriggerAverager {

  // private static final String TAG = TriggerAverager.class.getCanonicalName();
  private int maxsize;
  private short[] averagedSamples;
  private ArrayList<short[]> sampleBuffersInAverage;

  private Handler handler;
  private int triggerValue;
  private int lastTriggeredValue;

  public TriggerAverager(int size) {
    resetBuffers();
    setMaxsize(size);
    handler = new TriggerHandler();
  }

  public void resetBuffers() {
    sampleBuffersInAverage = new ArrayList<short[]>();
    averagedSamples = null;
  }

  public void push (ByteBuffer incoming) {
    incoming.clear();
    //Log.d(TAG, "Got buffer of samples: "+incoming.capacity());

    ShortBuffer sb = incoming.asShortBuffer();

    short[] incomingAsArray = new short [sb.capacity()];
    sb.get(incomingAsArray, 0, incomingAsArray.length);
    
    // Scan for triggers 

    
    for (int i = 0; i<incomingAsArray.length; i++) {
      short s = incomingAsArray[i];

      if ((triggerValue >= 0 && s > triggerValue) || (triggerValue < 0 && s < triggerValue)) {
        if(lastTriggeredValue != triggerValue) {
          resetBuffers();
          lastTriggeredValue = triggerValue;
        }
        incomingAsArray = wrapToCenter(incomingAsArray, i);
        pushToSampleBuffers(incomingAsArray);
      }
    }
    
    if (averagedSamples == null) {
      return;
    }
    
    for(int i = 0; i < averagedSamples.length; i++) {
      Integer curAvg = 0;
      for (short[] prev : sampleBuffersInAverage) {
        curAvg += prev[i];
      }
      curAvg /= sampleBuffersInAverage.size();
      averagedSamples[i] = curAvg.shortValue();
    }
  }

  private short[] wrapToCenter(short[] incomingAsArray, int index) {
    final int middleOfArray = incomingAsArray.length / 2;
    // create a new array to copy the adjusted samples into
    short [] sampleChunk = new short[incomingAsArray.length];
    int sampleChunkPosition = 0;
    if(index > middleOfArray) {
      // Log.d(TAG, "Wrapping from end onto beginning");
      final int samplesToMove = index - middleOfArray;
      for (int i = 0; i<incomingAsArray.length-samplesToMove; i++) {
        sampleChunk[sampleChunkPosition++] = incomingAsArray[i+samplesToMove];
      }
      for (int i = 0; i<samplesToMove; i++) {
        sampleChunk[sampleChunkPosition++] = incomingAsArray[i];
      }
    } else {
      // it's near beginning, wrap from end on to front
      // Log.d(TAG, "Wrapping from beginning onto end");
      final int samplesToMove = middleOfArray - index;
      for (int i = incomingAsArray.length - samplesToMove - 1; i < incomingAsArray.length; i++) {
        sampleChunk[sampleChunkPosition++] = incomingAsArray[i];
      }
      for (int i = 0; i<incomingAsArray.length - samplesToMove -1; i++) {
        sampleChunk[sampleChunkPosition++] = incomingAsArray[i];
      }
      
    }
    return sampleChunk;
  }

  private void pushToSampleBuffers(short[] incomingAsArray) {
    if (averagedSamples == null) {
      averagedSamples = incomingAsArray;
      sampleBuffersInAverage.add(incomingAsArray);
      return;
    }

    while (sampleBuffersInAverage.size() >= getMaxsize()) {
      sampleBuffersInAverage.remove(0);
    }
    
    sampleBuffersInAverage.add(incomingAsArray);
  }
  
  public short[] getAveragedSamples() {
    return averagedSamples;
  }
  
  public int getMaxsize() {
    return maxsize;
  }

  public void setMaxsize(int maxsize) {
    this.maxsize = maxsize;
  }

  public Handler getHandler() {
    return handler;
  }

  public class TriggerHandler extends Handler {
    public void setThreshold(float y) {
      //Log.d(TAG, "Got new triggerValue of "+y);
      triggerValue = (int) y;
    }
  }
}

Java Source Code List

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