TGTunerQueue.java

package org.herac.tuxguitar.gui.tools.custom.tuner;

import org.apache.log4j.Logger;

/**
 * Class that represents a frequency buffer that eliminates large frequency
 * fluctuations.
 * 
 * It is implemented as a queue list, where you put each frequency, and based on
 * QUEUE_SIZE last frequencies it determines what current dominant frequency
 * should be.
 * 
 * @author Nikola Kolarovic <johnny47ns@yahoo.com>
 * 
 */
public class TGTunerQueue {

  /** The Logger for this class. */
  public static final transient Logger LOG = Logger
      .getLogger(TGTunerQueue.class);

  /** pointer to index of the newest element */
  protected int head = 0;

  private final double lowerTollerance = 0.95; // -5%

  /** the frequency queue itself */
  protected double[] queue;

  /** size of the queue */
  int QUEUE_SIZE = 5;
  private double[] similars;

  // TODO: tweak the tollerances
  private final double upperTollerance = 1.05; // +5%

  public TGTunerQueue() {
    this.queue = new double[this.QUEUE_SIZE];
    this.similars = new double[this.QUEUE_SIZE];
    this.clear();
  }

  /** add new frequency to a queue */
  public void add(double newValue) {
    this.head = (++this.head) % this.QUEUE_SIZE;
    this.queue[this.head] = newValue;
  }

  /** clears the queue data */
  public void clear() {
    for (int i = 0; i < this.QUEUE_SIZE; i++)
      this.queue[i] = -1;
    this.head = 0;
  }

  /**
   * 
   * @return approximated frequency
   */
  public double getFreqApproximation() {

    for (int i = 0; i < this.QUEUE_SIZE; i++)
      this.similars[i] = -2; // -2, because it will always find 1 exact
                             // frequency when i==j

    for (int i = 0; i < this.QUEUE_SIZE; i++) {
      if (this.queue[i] != -1)
        for (int j = 0; j < this.QUEUE_SIZE; j++) {
          // exact frequency with tollerance
          if (this.queue[i] > (this.queue[j] * this.lowerTollerance)
              && this.queue[i] < (this.queue[j] * this.upperTollerance))
            this.similars[i] = this.similars[i] + 2;

          // half frequency with tollerance
          if (this.queue[i] / 2 > (this.queue[j] * this.lowerTollerance)
              && this.queue[i] / 2 < (this.queue[j] * this.upperTollerance))
            this.similars[i]++;

          // double frequency with tollerance
          if (this.queue[i] * 2 > (this.queue[j] * this.lowerTollerance)
              && this.queue[i] * 2 < (this.queue[j] * this.upperTollerance))
            this.similars[i]++;
        }
    }

    // find one with max similars
    int maxIndex = 0;
    for (int i = 1; i < this.QUEUE_SIZE; i++)
      if (this.similars[i] >= this.similars[maxIndex])
        maxIndex = i;

    /*
     * int test=(this.head+1)%this.QUEUE_SIZE;
     * LOG.debug(Math.floor(queue[head])+ " "); while (test!=this.head) {
     * LOG.debug(Math.floor(queue[test])+ " "); test = (++test)%this.QUEUE_SIZE;
     * 
     * } LOG.debug(" =  "+queue[maxIndex]%110+" **");
     */

    return this.queue[maxIndex];
    // return this.queue[head];

  }

}