/*
* _______ _____ _____ _____
* |__ __| | __ \ / ____| __ \
* | | __ _ _ __ ___ ___ ___| | | | (___ | |__) |
* | |/ _` | '__/ __|/ _ \/ __| | | |\___ \| ___/
* | | (_| | | \__ \ (_) \__ \ |__| |____) | |
* |_|\__,_|_| |___/\___/|___/_____/|_____/|_|
*
* -------------------------------------------------------------
*
* 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 <piem@aubio.org>
*
* @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<channels;i++) { */
for(int j=0;j<length-1;j++) {
onset_keep[j] = onset_keep[j+1];
onset_proc[j] = onset_keep[j];
}
onset_keep[length-1] = onset;
onset_proc[length-1] = onset;
/* filter onset_proc */
/** \bug filtfilt calculated post+pre times, should be only once !? */
biquad.doFiltering(onset_proc,scratch);
/* calculate mean and median for onset_proc */
/* copy to scratch */
float sum = 0.0f;
for (int j = 0; j < length; j++){
scratch[j] = onset_proc[j];
sum += scratch[j];
}
Arrays.sort(scratch);
median = scratch[scratch.length/2];
mean = sum/Float.valueOf(length);
/* shift peek array */
for (int j=0;j<3-1;j++){
onset_peek[j] = onset_peek[j+1];
}
/* calculate new peek value */
onset_peek[2] = (float) (onset_proc[win_post] - median - mean * threshold);
boolean isPeak = isPeak(1);
lastPeekValue = onset;
return isPeak;
}
/**
*
* @return The value of the last detected peak, or zero.
*/
public float getLastPeekValue() {
return lastPeekValue;
}
/**
* Returns true if the onset is a peak.
*
* @param index
* the index in onset_peak to check.
* @return True if the onset is a peak, false otherwise.
*/
private boolean isPeak(int index) {
return ( onset_peek[index] > onset_peek[index - 1] &&
onset_peek[index] > onset_peek[index + 1] &&
onset_peek[index] > 0.);
}
}