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/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*- vi:set ts=8 sts=4 sw=4: */
/*
pYIN - A fundamental frequency estimator for monophonic audio
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 "MonoNoteHMM.h"
#include <boost/math/distributions.hpp>
#include <cstdio>
#include <cmath>
using std::vector;
using std::pair;
MonoNoteHMM::MonoNoteHMM() :
par()
{
build();
}
const vector<double>
MonoNoteHMM::calculateObsProb(const vector<pair<double, double> > pitchProb)
{
// pitchProb is a list of pairs (pitches and their probabilities)
size_t nCandidate = pitchProb.size();
// what is the probability of pitched
double pIsPitched = 0;
for (size_t iCandidate = 0; iCandidate < nCandidate; ++iCandidate)
{
// pIsPitched = pitchProb[iCandidate].second > pIsPitched ? pitchProb[iCandidate].second : pIsPitched;
pIsPitched += pitchProb[iCandidate].second;
}
// pIsPitched = std::pow(pIsPitched, (1-par.priorWeight)) * std::pow(par.priorPitchedProb, par.priorWeight);
pIsPitched = pIsPitched * (1-par.priorWeight) + par.priorPitchedProb * par.priorWeight;
vector<double> out = vector<double>(par.n);
double tempProbSum = 0;
for (size_t i = 0; i < par.n; ++i)
{
if (i % par.nSPP != 2)
{
// std::cerr << getMidiPitch(i) << std::endl;
double tempProb = 0;
if (nCandidate > 0)
{
double minDist = 10000.0;
double minDistProb = 0;
size_t minDistCandidate = 0;
for (size_t iCandidate = 0; iCandidate < nCandidate; ++iCandidate)
{
double currDist = std::abs(getMidiPitch(i)-pitchProb[iCandidate].first);
if (currDist < minDist)
{
minDist = currDist;
minDistProb = pitchProb[iCandidate].second;
minDistCandidate = iCandidate;
}
}
tempProb = std::pow(minDistProb, par.yinTrust) *
boost::math::pdf(pitchDistr[i],
pitchProb[minDistCandidate].first);
} else {
tempProb = 1;
}
tempProbSum += tempProb;
out[i] = tempProb;
}
}
for (size_t i = 0; i < par.n; ++i)
{
if (i % par.nSPP != 2)
{
if (tempProbSum > 0)
{
out[i] = out[i] / tempProbSum * pIsPitched;
}
} else {
out[i] = (1-pIsPitched) / (par.nPPS * par.nS);
}
}
return(out);
}
void
MonoNoteHMM::build()
{
// the states are organised as follows:
// 0-2. lowest pitch
// 0. attack state
// 1. stable state
// 2. silent state
// 3-5. second-lowest pitch
// 3. attack state
// ...
// observation distributions
for (size_t iState = 0; iState < par.n; ++iState)
{
pitchDistr.push_back(boost::math::normal(0,1));
if (iState % par.nSPP == 2)
{
// silent state starts tracking
init.push_back(1.0/(par.nS * par.nPPS));
} else {
init.push_back(0.0);
}
}
for (size_t iPitch = 0; iPitch < (par.nS * par.nPPS); ++iPitch)
{
size_t index = iPitch * par.nSPP;
double mu = par.minPitch + iPitch * 1.0/par.nPPS;
pitchDistr[index] = boost::math::normal(mu, par.sigmaYinPitchAttack);
pitchDistr[index+1] = boost::math::normal(mu, par.sigmaYinPitchStable);
pitchDistr[index+2] = boost::math::normal(mu, 1.0); // dummy
}
boost::math::normal noteDistanceDistr(0, par.sigma2Note);
for (size_t iPitch = 0; iPitch < (par.nS * par.nPPS); ++iPitch)
{
// loop through all notes and set sparse transition probabilities
size_t index = iPitch * par.nSPP;
// transitions from attack state
from.push_back(index);
to.push_back(index);
transProb.push_back(par.pAttackSelftrans);
from.push_back(index);
to.push_back(index+1);
transProb.push_back(1-par.pAttackSelftrans);
// transitions from stable state
from.push_back(index+1);
to.push_back(index+1); // to itself
transProb.push_back(par.pStableSelftrans);
from.push_back(index+1);
to.push_back(index+2); // to silent
transProb.push_back(par.pStable2Silent);
// the "easy" transitions from silent state
from.push_back(index+2);
to.push_back(index+2);
transProb.push_back(par.pSilentSelftrans);
// the more complicated transitions from the silent
double probSumSilent = 0;
vector<double> tempTransProbSilent;
for (size_t jPitch = 0; jPitch < (par.nS * par.nPPS); ++jPitch)
{
int fromPitch = iPitch;
int toPitch = jPitch;
double semitoneDistance =
std::abs(fromPitch - toPitch) * 1.0 / par.nPPS;
// if (std::fmod(semitoneDistance, 1) == 0 && semitoneDistance > par.minSemitoneDistance)
if (semitoneDistance == 0 ||
(semitoneDistance > par.minSemitoneDistance
&& semitoneDistance < par.maxJump))
{
size_t toIndex = jPitch * par.nSPP; // note attack index
double tempWeightSilent = boost::math::pdf(noteDistanceDistr,
semitoneDistance);
probSumSilent += tempWeightSilent;
tempTransProbSilent.push_back(tempWeightSilent);
from.push_back(index+2);
to.push_back(toIndex);
}
}
for (size_t i = 0; i < tempTransProbSilent.size(); ++i)
{
transProb.push_back((1-par.pSilentSelftrans) * tempTransProbSilent[i]/probSumSilent);
}
}
}
double
MonoNoteHMM::getMidiPitch(size_t index)
{
return pitchDistr[index].mean();
}
double
MonoNoteHMM::getFrequency(size_t index)
{
return 440 * pow(2, (pitchDistr[index].mean()-69)/12);
}
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