annotate dsp/segmentation/cluster_melt.c @ 96:88f3cfcff55f

A threshold (delta) is added in the peak picking parameters structure (PPickParams). It is used as an offset when computing the smoothed detection function. A constructor for the structure PPickParams is also added to set the parameters to 0 when a structure instance is created. Hence programmes using the peak picking parameter structure and which do not set the delta parameter (e.g. QM Vamp note onset detector) won't be affected by the modifications.

Functions modified:
- dsp/onsets/PeakPicking.cpp
- dsp/onsets/PeakPicking.h
- dsp/signalconditioning/DFProcess.cpp
- dsp/signalconditioning/DFProcess.h

/*
 *  cluster.c
 *  cluster_melt
 *
 *  Created by Mark Levy on 21/02/2006.
 *  Copyright 2006 Centre for Digital Music, Queen Mary, University of London.

    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 2 of the
    License, or (at your option) any later version.  See the file
    COPYING included with this distribution for more information.
 *
 */

#include <stdlib.h>

#include "cluster_melt.h"

#define DEFAULT_LAMBDA 0.02;
#define DEFAULT_LIMIT 20;

double kldist(double* a, double* b, int n) {
	/* NB assume that all a[i], b[i] are non-negative
	because a, b represent probability distributions */
	double q, d;
	int i;
	
	d = 0;
	for (i = 0; i < n; i++)
	{
		q = (a[i] + b[i]) / 2.0;
		if (q > 0)
		{
			if (a[i] > 0)
				d += a[i] * log(a[i] / q);
			if (b[i] > 0)
				d += b[i] * log(b[i] / q);
		}
	}
	return d;		
}	

void cluster_melt(double *h, int m, int n, double *Bsched, int t, int k, int l, int *c) {
	double lambda, sum, beta, logsumexp, maxlp;
	int i, j, a, b, b0, b1, limit, B, it, maxiter, maxiter0, maxiter1;
	double** cl;	/* reference histograms for each cluster */
	int** nc;	/* neighbour counts for each histogram */
	double** lp;	/* soft assignment probs for each histogram */
	int* oldc;	/* previous hard assignments (to check convergence) */
	
	/* NB h is passed as a 1d row major array */
	
	/* parameter values */
	lambda = DEFAULT_LAMBDA;
	if (l > 0)
		limit = l;
	else
		limit = DEFAULT_LIMIT;		/* use default if no valid neighbourhood limit supplied */
	B = 2 * limit + 1;
	maxiter0 = 20;	/* number of iterations at initial temperature */
	maxiter1 = 5;	/* number of iterations at subsequent temperatures */
	
	/* allocate memory */	
	cl = (double**) malloc(k*sizeof(double*));
	for (i= 0; i < k; i++)
		cl[i] = (double*) malloc(m*sizeof(double));
	
	nc = (int**) malloc(n*sizeof(int*));
	for (i= 0; i < n; i++)
		nc[i] = (int*) malloc(k*sizeof(int));
	
	lp = (double**) malloc(n*sizeof(double*));
	for (i= 0; i < n; i++)
		lp[i] = (double*) malloc(k*sizeof(double));
	
	oldc = (int*) malloc(n * sizeof(int));
	
	/* initialise */
	for (i = 0; i < k; i++)
	{
		sum = 0;
		for (j = 0; j < m; j++)
		{
			cl[i][j] = rand();	/* random initial reference histograms */
			sum += cl[i][j] * cl[i][j];
		}
		sum = sqrt(sum);
		for (j = 0; j < m; j++)
		{
			cl[i][j] /= sum;	/* normalise */
		}
	}	
	//print_array(cl, k, m);
	
	for (i = 0; i < n; i++)
		c[i] = 1;	/* initially assign all histograms to cluster 1 */
	
	for (a = 0; a < t; a++)
	{
		beta = Bsched[a];
		
		if (a == 0)
			maxiter = maxiter0;
		else
			maxiter = maxiter1;
		
		for (it = 0; it < maxiter; it++)
		{
			//if (it == maxiter - 1)
			//	mexPrintf("hasn't converged after %d iterations\n", maxiter);
			
			for (i = 0; i < n; i++)
			{
				/* save current hard assignments */
				oldc[i] = c[i];
				
				/* calculate soft assignment logprobs for each cluster */
				sum = 0;
				for (j = 0; j < k; j++)
				{
					lp[i][ j] = -beta * kldist(cl[j], &h[i*m], m);
					
					/* update matching neighbour counts for this histogram, based on current hard assignments */
					/* old version:
					nc[i][j] = 0;	
					if (i >= limit && i <= n - 1 - limit)
					{
							for (b = i - limit; b <= i + limit; b++)
							{
								if (c[b] == j+1)
									nc[i][j]++;
							}
							nc[i][j] = B - nc[i][j];
					}
					*/
					b0 = i - limit;
					if (b0 < 0)
						b0 = 0;
					b1 = i + limit;
					if (b1 >= n)
						b1 = n - 1;
					nc[i][j] = b1 - b0 + 1;		/* = B except at edges */
					for (b = b0; b <= b1; b++)
						if (c[b] == j+1)
							nc[i][j]--;
					
					sum += exp(lp[i][j]);
				}
				
				/* normalise responsibilities and add duration logprior */
				logsumexp = log(sum);
				for (j = 0; j < k; j++)
					lp[i][j] -= logsumexp + lambda * nc[i][j];				
			}
			//print_array(lp, n, k);
			/*
			for (i = 0; i < n; i++)
			{
				 for (j = 0; j < k; j++)
					 mexPrintf("%d ", nc[i][j]);
				 mexPrintf("\n");
			} 
			*/
			
			
			/* update the assignments now that we know the duration priors
			based on the current assignments */
			for (i = 0; i < n; i++)
			{
				maxlp = lp[i][0];
				c[i] = 1;
				for (j = 1; j < k; j++)
					if (lp[i][j] > maxlp)
					{
						maxlp = lp[i][j];
						c[i] = j+1;
					}
			}
				
			/* break if assignments haven't changed */
			i = 0;
			while (i < n && oldc[i] == c[i])
				i++;
			if (i == n)
				break;
			
			/* update reference histograms now we know new responsibilities */
			for (j = 0; j < k; j++)
			{
				for (b = 0; b < m; b++)
				{
					cl[j][b] = 0;
					for (i = 0; i < n; i++)
					{
						cl[j][b] += exp(lp[i][j]) * h[i*m+b];
					}	
				}
				
				sum = 0;				
				for (i = 0; i < n; i++)
					sum += exp(lp[i][j]);
				for (b = 0; b < m; b++)
					cl[j][b] /= sum;	/* normalise */
			}	
			
			//print_array(cl, k, m);
			//mexPrintf("\n\n");
		}
	}
		
	/* free memory */
	for (i = 0; i < k; i++)
		free(cl[i]);
	free(cl);
	for (i = 0; i < n; i++)
		free(nc[i]);
	free(nc);
	for (i = 0; i < n; i++)
		free(lp[i]);
	free(lp);
	free(oldc);	
}