annotate src/BTrack.cpp @ 18:450c53430540 develop

Changed the interface of the algorithm so that onset detection function samples are calculated internally. This makes the call to the algorithm for most cases much simpler. Also added a static function for calculating beat times in seconds based upon sampling frequency, hop size and the current frame number.

//=======================================================================
/** @file BTrack.cpp
 *  @brief BTrack - a real-time beat tracker
 *  @author Adam Stark
 *  @copyright Copyright (C) 2008-2014  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 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/>.
 */
//=======================================================================

#include <cmath>
#include <algorithm>
#include "BTrack.h"
#include "samplerate.h"

//=======================================================================
BTrack::BTrack() : odf(512,1024,6,1)
{
    initialise(512, 1024);
}

//=======================================================================
BTrack::BTrack(int hopSize) : odf(hopSize,2*hopSize,6,1)
{	
    initialise(hopSize, 2*hopSize);
}

//=======================================================================
BTrack::BTrack(int hopSize,int frameSize) : odf(hopSize,frameSize,6,1)
{
    initialise(hopSize, frameSize);
}

//=======================================================================
BTrack::~BTrack()
{	
	
}

//=======================================================================
double BTrack::getBeatTimeInSeconds(long frameNumber,int hopSize,int fs)
{
    double hop = (double) hopSize;
    double samplingFrequency = (double) fs;
    double frameNum = (double) frameNumber;
    
    return ((hop / samplingFrequency) * frameNum);
}

//=======================================================================
double BTrack::getBeatTimeInSeconds(int frameNumber,int hopSize,int fs)
{
    long frameNum = (long) frameNumber;
    
    return getBeatTimeInSeconds(frameNum, hopSize, fs);
}



//=======================================================================
void BTrack::initialise(int hopSize, int frameSize)
{
    double rayparam = 43;
	double pi = 3.14159265;
	
	
	// initialise parameters
	tightness = 5;
	alpha = 0.9;
	tempo = 120;
	est_tempo = 120;
	p_fact = 60.*44100./512.;
	
	m0 = 10;
	beat = -1;
	
	playbeat = 0;
	
	
	
	
	// create rayleigh weighting vector
	for (int n = 0;n < 128;n++)
	{
		wv[n] = ((double) n / pow(rayparam,2)) * exp((-1*pow((double)-n,2)) / (2*pow(rayparam,2)));
	}
	
	// initialise prev_delta
	for (int i = 0;i < 41;i++)
	{
		prev_delta[i] = 1;
	}
	
	double t_mu = 41/2;
	double m_sig;
	double x;
	// create tempo transition matrix
	m_sig = 41/8;
	for (int i = 0;i < 41;i++)
	{
		for (int j = 0;j < 41;j++)
		{
			x = j+1;
			t_mu = i+1;
			t_tmat[i][j] = (1 / (m_sig * sqrt(2*pi))) * exp( (-1*pow((x-t_mu),2)) / (2*pow(m_sig,2)) );
		}
	}
	
	// tempo is not fixed
	tempofix = 0;
    
    // initialise algorithm given the hopsize
    setHopSize(hopSize);
}

//=======================================================================
void BTrack :: setHopSize(int hopSize)
{	
	framesize = hopSize;
	dfbuffer_size = (512*512)/hopSize;		// calculate df buffer size
	
	bperiod = round(60/((((double) hopSize)/44100)*tempo));
	
	dfbuffer = new double[dfbuffer_size];	// create df_buffer
	cumscore = new double[dfbuffer_size];	// create cumscore
	
	
	// initialise df_buffer to zeros
	for (int i = 0;i < dfbuffer_size;i++)
	{
		dfbuffer[i] = 0;
		cumscore[i] = 0;
		
		
		if ((i %  ((int) round(bperiod))) == 0)
		{
			dfbuffer[i] = 1;
		}
	}
}

//=======================================================================
void BTrack::processAudioFrame(double *frame)
{
    // calculate the onset detection function sample for the frame
    double sample = odf.getDFsample(frame);
    
    // add a tiny constant to the sample to stop it from ever going
    // to zero. this is to avoid problems further down the line
    sample = sample + 0.0001;
    
    // process the new onset detection function sample in the beat tracking algorithm
    processOnsetDetectionFunctionSample(sample);
}

//=======================================================================
void BTrack::processOnsetDetectionFunctionSample(double newSample)
{	 
	m0--;
	beat--;
	playbeat = 0;
	
	// move all samples back one step
	for (int i=0;i < (dfbuffer_size-1);i++)
	{
		dfbuffer[i] = dfbuffer[i+1];
	}
	
	// add new sample at the end
	dfbuffer[dfbuffer_size-1] = newSample;
	
	// update cumulative score
	updatecumscore(newSample);
	
	// if we are halfway between beats
	if (m0 == 0)
	{
		predictbeat();
	}
	
	// if we are at a beat
	if (beat == 0)
	{
		playbeat = 1;	// indicate a beat should be output
		
		// recalculate the tempo
		dfconvert();	
		calcTempo();
	}
}

//=======================================================================
void BTrack :: settempo(double tempo)
{	 
	
	/////////// TEMPO INDICATION RESET //////////////////
	
	// firstly make sure tempo is between 80 and 160 bpm..
	while (tempo > 160)
	{
		tempo = tempo/2;
	}
	
	while (tempo < 80)
	{
		tempo = tempo * 2;
	}
		
	// convert tempo from bpm value to integer index of tempo probability 
	int tempo_index = (int) round((tempo - 80)/2);
	
	// now set previous tempo observations to zero
	for (int i=0;i < 41;i++)
	{
		prev_delta[i] = 0;
	}
	
	// set desired tempo index to 1
	prev_delta[tempo_index] = 1;
	
	
	/////////// CUMULATIVE SCORE ARTIFICAL TEMPO UPDATE //////////////////
	
	// calculate new beat period
	int new_bperiod = (int) round(60/((((double) framesize)/44100)*tempo));
	
	int bcounter = 1;
	// initialise df_buffer to zeros
	for (int i = (dfbuffer_size-1);i >= 0;i--)
	{
		if (bcounter == 1)
		{
			cumscore[i] = 150;
			dfbuffer[i] = 150;
		}
		else
		{
			cumscore[i] = 10;
			dfbuffer[i] = 10;
		}
		
		bcounter++;
		
		if (bcounter > new_bperiod)
		{
			bcounter = 1;
		}
	}
	
	/////////// INDICATE THAT THIS IS A BEAT //////////////////
	
	// beat is now
	beat = 0;
	
	// offbeat is half of new beat period away
	m0 = (int) round(((double) new_bperiod)/2);
}

//=======================================================================
void BTrack :: fixtempo(double tempo)
{	
	// firstly make sure tempo is between 80 and 160 bpm..
	while (tempo > 160)
	{
		tempo = tempo/2;
	}
	
	while (tempo < 80)
	{
		tempo = tempo * 2;
	}
	
	// convert tempo from bpm value to integer index of tempo probability 
	int tempo_index = (int) round((tempo - 80)/2);
	
	// now set previous fixed previous tempo observation values to zero
	for (int i=0;i < 41;i++)
	{
		prev_delta_fix[i] = 0;
	}
	
	// set desired tempo index to 1
	prev_delta_fix[tempo_index] = 1;
		
	// set the tempo fix flag
	tempofix = 1;	
}

//=======================================================================
void BTrack :: unfixtempo()
{	
	// set the tempo fix flag
	tempofix = 0;	
}

//=======================================================================
void BTrack :: dfconvert()
{
	float output[512];
    float input[dfbuffer_size];
    
    for (int i = 0;i < dfbuffer_size;i++)
    {
        input[i] = (float) dfbuffer[i];
    }
		
	double src_ratio = 512.0/((double) dfbuffer_size);
	int BUFFER_LEN = dfbuffer_size;
	int output_len;
	SRC_DATA	src_data ;
	
	//output_len = (int) floor (((double) BUFFER_LEN) * src_ratio) ;
	output_len = 512;
	
	src_data.data_in = input;
	src_data.input_frames = BUFFER_LEN;
	
	src_data.src_ratio = src_ratio;
	
	src_data.data_out = output;
	src_data.output_frames = output_len;
	
	src_simple (&src_data, SRC_SINC_BEST_QUALITY, 1);
			
	for (int i = 0;i < output_len;i++)
	{
		df512[i] = (double) src_data.data_out[i];
	}
}

//=======================================================================
void BTrack :: calcTempo()
{
	// adaptive threshold on input
	adapt_thresh(df512,512);
		
	// calculate auto-correlation function of detection function
	acf_bal(df512);
	
	// calculate output of comb filterbank
	getrcfoutput();
	
	
	// adaptive threshold on rcf
	adapt_thresh(rcf,128);

	
	int t_index;
	int t_index2;
	// calculate tempo observation vector from bperiod observation vector
	for (int i = 0;i < 41;i++)
	{
		t_index = (int) round(p_fact / ((double) ((2*i)+80)));
		t_index2 = (int) round(p_fact / ((double) ((4*i)+160)));

		
		t_obs[i] = rcf[t_index-1] + rcf[t_index2-1];
	}
	
	
	double maxval;
	double maxind;
	double curval;
	
	// if tempo is fixed then always use a fixed set of tempi as the previous observation probability function
	if (tempofix == 1)
	{
		for (int k = 0;k < 41;k++)
		{
			prev_delta[k] = prev_delta_fix[k];
		}
	}
		
	for (int j=0;j < 41;j++)
	{
		maxval = -1;
		for (int i = 0;i < 41;i++)
		{
			curval = prev_delta[i]*t_tmat[i][j];
			
			if (curval > maxval)
			{
				maxval = curval;
			}
		}
		
		delta[j] = maxval*t_obs[j];
	}
	

	normalise(delta,41);
	
	maxind = -1;
	maxval = -1;
	
	for (int j=0;j < 41;j++)
	{
		if (delta[j] > maxval)
		{
			maxval = delta[j];
			maxind = j;
		}
		
		prev_delta[j] = delta[j];
	}
	
	bperiod = round((60.0*44100.0)/(((2*maxind)+80)*((double) framesize)));
	
	if (bperiod > 0)
	{
		est_tempo = 60.0/((((double) framesize) / 44100.0)*bperiod);
	}
	
	//cout << bperiod << endl;
}

//=======================================================================
void BTrack :: adapt_thresh(double *x,int N)
{
	//int N = 512; // length of df
	int i = 0;
	int k,t = 0;
	double x_thresh[N];
	
	int p_post = 7;
	int p_pre = 8;
	
	t = std::min(N,p_post);	// what is smaller, p_post of df size. This is to avoid accessing outside of arrays
	
	// find threshold for first 't' samples, where a full average cannot be computed yet 
	for (i = 0;i <= t;i++)
	{	
		k = std::min((i+p_pre),N);
		x_thresh[i] = mean_array(x,1,k);
	}
	// find threshold for bulk of samples across a moving average from [i-p_pre,i+p_post]
	for (i = t+1;i < N-p_post;i++)
	{
		x_thresh[i] = mean_array(x,i-p_pre,i+p_post);
	}
	// for last few samples calculate threshold, again, not enough samples to do as above
	for (i = N-p_post;i < N;i++)
	{
		k = std::max((i-p_post),1);
		x_thresh[i] = mean_array(x,k,N);
	}
	
	// subtract the threshold from the detection function and check that it is not less than 0
	for (i = 0;i < N;i++)
	{
		x[i] = x[i] - x_thresh[i];
		if (x[i] < 0)
		{
			x[i] = 0;
		}
	}
}

//=======================================================================
void BTrack :: getrcfoutput()
{
	int numelem;
	
	for (int i = 0;i < 128;i++)
	{
		rcf[i] = 0;
	}
	
	numelem = 4;
	
	for (int i = 2;i <= 127;i++) // max beat period
	{
		for (int a = 1;a <= numelem;a++) // number of comb elements
		{
			for (int b = 1-a;b <= a-1;b++) // general state using normalisation of comb elements
			{
				rcf[i-1] = rcf[i-1] + (acf[(a*i+b)-1]*wv[i-1])/(2*a-1);	// calculate value for comb filter row
			}
		}
	}
}

//=======================================================================
void BTrack :: acf_bal(double *df_thresh)
{
	int l, n = 0;
	double sum, tmp;
	
	// for l lags from 0-511
	for (l = 0;l < 512;l++)
	{
		sum = 0;	
		
		// for n samples from 0 - (512-lag)
		for (n = 0;n < (512-l);n++)
		{
			tmp = df_thresh[n] * df_thresh[n+l];	// multiply current sample n by sample (n+l)
			sum = sum + tmp;	// add to sum
		}
		
		acf[l] = sum / (512-l);		// weight by number of mults and add to acf buffer
	}
}

//=======================================================================
double BTrack :: mean_array(double *array,int start,int end)
{
	int i;
	double sum = 0;

    int length = end - start;
	
	// find sum
	for (i = start;i < end;i++)
	{
		sum = sum + array[i];
	}
	
    if (length > 0)
    {
        return sum / length;	// average and return
    }
    else
    {
        return 0;
    }
}

//=======================================================================
void BTrack :: normalise(double *array,int N)
{
	double sum = 0;
	
	for (int i = 0;i < N;i++)
	{
		if (array[i] > 0)
		{
			sum = sum + array[i];
		}
	}
	
	if (sum > 0)
	{
		for (int i = 0;i < N;i++)
		{
			array[i] = array[i] / sum;
		}
	}
}

//=======================================================================
void BTrack :: updatecumscore(double df_sample)
{	 
	int start, end, winsize;
	double max;
	
	start = dfbuffer_size - round(2*bperiod);
	end = dfbuffer_size - round(bperiod/2);
	winsize = end-start+1;
	
	double w1[winsize];
	double v = -2*bperiod;
	double wcumscore;
	
	
	// create window
	for (int i = 0;i < winsize;i++)
	{
		w1[i] = exp((-1*pow(tightness*log(-v/bperiod),2))/2);
		v = v+1;
	}	
	
	// calculate new cumulative score value
	max = 0;
	int n = 0;
	for (int i=start;i <= end;i++)
	{
			wcumscore = cumscore[i]*w1[n];
		
			if (wcumscore > max)
			{
				max = wcumscore;
			}
		n++;
	}
	
	
	// shift cumulative score back one
	for (int i = 0;i < (dfbuffer_size-1);i++)
	{
		cumscore[i] = cumscore[i+1];
	}
	
	// add new value to cumulative score
	cumscore[dfbuffer_size-1] = ((1-alpha)*df_sample) + (alpha*max);
	
	cscoreval = cumscore[dfbuffer_size-1];
	
	//cout << cumscore[dfbuffer_size-1] << endl;
		
}

//=======================================================================
void BTrack :: predictbeat()
{	 
	int winsize = (int) bperiod;
	double fcumscore[dfbuffer_size + winsize];
	double w2[winsize];
	// copy cumscore to first part of fcumscore
	for (int i = 0;i < dfbuffer_size;i++)
	{
		fcumscore[i] = cumscore[i];
	}
	
	// create future window
	double v = 1;
	for (int i = 0;i < winsize;i++)
	{
		w2[i] = exp((-1*pow((v - (bperiod/2)),2))   /  (2*pow((bperiod/2) ,2)));
		v++;
	}
	
	// create past window
	v = -2*bperiod;
	int start = dfbuffer_size - round(2*bperiod);
	int end = dfbuffer_size - round(bperiod/2);
	int pastwinsize = end-start+1;
	double w1[pastwinsize];

	for (int i = 0;i < pastwinsize;i++)
	{
		w1[i] = exp((-1*pow(tightness*log(-v/bperiod),2))/2);
		v = v+1;
	}

	

	// calculate future cumulative score
	double max;
	int n;
	double wcumscore;
	for (int i = dfbuffer_size;i < (dfbuffer_size+winsize);i++)
	{
		start = i - round(2*bperiod);
		end = i - round(bperiod/2);
		
		max = 0;
		n = 0;
		for (int k=start;k <= end;k++)
		{
			wcumscore = fcumscore[k]*w1[n];
			
			if (wcumscore > max)
			{
				max = wcumscore;
			}
			n++;
		}
		
		fcumscore[i] = max;
	}
	
	
	// predict beat
	max = 0;
	n = 0;
	
	for (int i = dfbuffer_size;i < (dfbuffer_size+winsize);i++)
	{
		wcumscore = fcumscore[i]*w2[n];
		
		if (wcumscore > max)
		{
			max = wcumscore;
			beat = n;
		}	
		
		n++;
	}
		
	// set next prediction time
	m0 = beat+round(bperiod/2);
	

}