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TarsosDSP library
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/*
*      _______                       _____   _____ _____  
*     |__   __|                     |  __ \ / ____|  __ \ 
*        | | __ _ _ __ ___  ___  ___| |  | | (___ | |__) |
*        | |/ _` | '__/ __|/ _ \/ __| |  | |\___ \|  ___/ 
*        | | (_| | |  \__ \ (_) \__ \ |__| |____) | |     
*        |_|\__,_|_|  |___/\___/|___/_____/|_____/|_|     
*                                                         
* -------------------------------------------------------------
*
* TarsosDSP is developed by Joren Six at IPEM, University Ghent
*  
* -------------------------------------------------------------
*
*  Info: http://0110.be/tag/TarsosDSP
*  Github: https://github.com/JorenSix/TarsosDSP
*  Releases: http://0110.be/releases/TarsosDSP/
*  
*  TarsosDSP includes modified source code by various authors,
*  for credits and info, see README.
* 
*/

package be.tarsos.dsp.util;

import java.util.Arrays;

/**
 * Implements a moving mean adaptive threshold peak picker.
 * 
 * The implementation is a translation of peakpicker.c from Aubio, Copyright (C)
 * 2003-2009 Paul Brossier 
 * 
 * @author Joren Six
 * @author Paul Brossiers
 */
public class PeakPicker {
	/** thresh: offset threshold [0.033 or 0.01] */
	private double threshold;
	/** win_post: median filter window length (causal part) [8] */
	private int win_post;
	/** pre: median filter window (anti-causal part) [post-1] */
	private int win_pre;
	
	/** biquad low pass filter */
	private BiQuadFilter biquad;
	
	/** original onsets */
	private float[] onset_keep;
	/** modified onsets */
	private float[] onset_proc;
	/** peak picked window [3] */
	private float[] onset_peek;
	/** scratch pad for biquad and median */
	private float[] scratch;
	
	private float lastPeekValue;
	
	/**
	 * Initializes a new moving mean adaptive threshold peak picker.
	 * 
	 * @param threshold
	 *            The threshold defines when a peak is selected. It should be
	 *            between zero and one, 0.3 is a reasonable value. If too many
	 *            peaks are detected go to 0.5 - 0.8.
	 */
	public PeakPicker(double threshold) {
		/* Low-pass filter cutoff [0.34, 1] */		
		biquad = new BiQuadFilter(0.1600,0.3200,0.1600,-0.5949,0.2348);
		this.threshold = threshold;
		win_post = 5;
		win_pre = 1;
		
		onset_keep = new float[win_post + win_pre +1];
		onset_proc =  new float[win_post + win_pre +1];
		scratch =  new float[win_post + win_pre +1];
		onset_peek = new float[3];		
	}
	
	/**
	 * Sets a new threshold.
	 * 
	 * @param threshold
	 *            The threshold defines when a peak is selected. It should be
	 *            between zero and one, 0.3 is a reasonable value. If too many
	 *            peaks are detected go to 0.5 - 0.8.
	 */
	public void setThreshold(double threshold) {
		this.threshold = threshold;
	}
	
	/**
	 * Modified version for real time, moving mean adaptive threshold this
	 * method is slightly more permissive than the off-LineWavelet one, and yields to
	 * an increase of false positives.
	 * 
	 * @param onset
	 *            The new onset value.
	 * @return True if a peak is detected, false otherwise.
	 **/
	public boolean pickPeak(float onset) {
		float mean = 0.f;
		float median = 0.f;
		
		int length = win_post + win_pre + 1;
		
		
		/* store onset in onset_keep */
		/* shift all elements but last, then write last */
		/* for (i=0;i onset_peek[index - 1] &&
					onset_peek[index] > onset_peek[index + 1] && 
					onset_peek[index] > 0.);
	}
}