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segcosine.cpp
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segcosine.cpp
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/*************************************************************************
Copyright 2011-2013 Ibrahim Sha'ath
This file is part of LibKeyFinder.
LibKeyFinder 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.
LibKeyFinder 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 LibKeyFinder. If not, see <http://www.gnu.org/licenses/>.
*************************************************************************/
#include "segcosine.h"
namespace KeyFinder{
std::vector<float> CosineHcdf::getRateOfChange(const Chromagram& ch, const Parameters& params) const{
unsigned int hops = ch.getHops();
unsigned int bins = ch.getBins();
unsigned int gaussianSize = params.getSegGaussianSize();
float gaussianSigma = params.getSegGaussianSigma();
unsigned int padding = 0; // as opposed to gaussianSize/2
std::vector<float> cosine(hops+padding, 0.0);
for (unsigned int hop = 0; hop < hops; hop++){
float top = 0.0;
float bottom = 0.0;
for (unsigned int bin = 0; bin < bins; bin++){
float mag = ch.getMagnitude(hop, bin);
top += mag;
bottom += pow(mag,2);
}
float cos;
if(bottom > 0.0) // divzero
cos = top / sqrt(bottom) * sqrt(bins * sqrt(2));
else
cos = 0.0;
cosine[hop] = cos;
}
// gaussian
std::vector<float> gaussian(gaussianSize);
for (unsigned int i=0; i<gaussianSize; i++){
gaussian[i] = exp(-1 * (pow(i - gaussianSize/2 , 2) / (2 * gaussianSigma * gaussianSigma)));
}
std::vector<float> smoothed(hops);
for (unsigned int hop = padding; hop < cosine.size(); hop++){
float conv = 0.0;
for (unsigned int k=0; k<gaussianSize; k++){
int frm = hop - (gaussianSize/2) + k;
if(frm >= 0 && frm < (signed)cosine.size()){
conv += cosine[frm] * gaussian[k];
}
}
smoothed[hop-padding] = conv;
}
// rate of change of hcdf signal; look at all hops except first.
std::vector<float> rateOfChange(hops, 0.0);
for (unsigned int hop=1; hop<hops; hop++){
float change = (smoothed[hop] - smoothed[hop-1]) / 90.0;
change = (change >= 0 ? change : change * -1.0);
change /= 0.16; // TODO: fix awful magic number for display purposes in KeyFinder GUI app
rateOfChange[hop] = change;
}
// fudge first
rateOfChange[0] = rateOfChange[1];
return rateOfChange;
}
std::vector<unsigned int> CosineHcdf::getSegments(const std::vector<float>& rateOfChange, const Parameters& params) const{
// Pick peaks
std::vector<unsigned int> changes(1, 0); // start vector with a 0 to enable first classification
unsigned int neighbours = params.getSegPeakPickingNeighbours();
for (unsigned int hop = 0; hop < rateOfChange.size(); hop++){
bool peak = true;
for (int i = -neighbours; i <= (signed)neighbours; i++)
if(i != 0 && hop+i < rateOfChange.size()) // only test valid neighbours
if(rateOfChange[hop+i] >= rateOfChange[hop])
peak = false; // there's a neighbour of higher or equal value; this isn't a peak
if(peak)
changes.push_back(hop);
}
return changes;
}
}