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MonoNote.cpp
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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 "MonoNote.h"
#include <vector>
#include <cstdio>
#include <cmath>
#include <complex>
using std::vector;
using std::pair;
MonoNote::MonoNote(bool fixedLag) :
m_fixedLag(fixedLag),
hmm(m_fixedLag ? 1000 : 0)
{
}
MonoNote::~MonoNote()
{
}
const vector<MonoNote::FrameOutput>
MonoNote::process(const vector<vector<pair<double, double> > > pitchProb)
{
// Previously, this built up a single matrix of probabilities, by
// calling calculateObsProb to get a column for each frame in
// pitchProb.
//
// The number of distinct states depends on MonoNoteParameters,
// but the defaults have 3 states per pitch, 3 pitches per MIDI
// note, and 69 MIDI notes, giving 681 states per frame. With a
// frame step size of 256 at 44100Hz sample rate, a 3-minute song
// has about 30K frames leading to a 20 million element
// probability matrix.
//
// Since the matrix is very sparse, we can avoid some of this by
// feeding the (sparse implementation of) HMM one column at a
// time.
vector<int> path;
path.reserve(pitchProb.size());
if (!pitchProb.empty()) {
hmm.initialise(hmm.calculateObsProb(pitchProb[0]));
for (size_t iFrame = 1; iFrame < pitchProb.size(); ++iFrame)
{
if (m_fixedLag && (int(iFrame) >= hmm.m_fixedLag))
{
vector<int> rawPath = hmm.track();
path.push_back(rawPath[0]);
}
hmm.process(hmm.calculateObsProb(pitchProb[iFrame]));
}
vector<int> rawPath = hmm.track();
path.insert(path.end(), rawPath.begin(), rawPath.end());
}
vector<MonoNote::FrameOutput> out;
out.reserve(path.size());
for (size_t iFrame = 0; iFrame < path.size(); ++iFrame)
{
double currPitch = -1;
int stateKind = 0;
currPitch = hmm.par.minPitch + (path[iFrame]/hmm.par.nSPP) * 1.0/hmm.par.nPPS;
stateKind = (path[iFrame]) % hmm.par.nSPP + 1;
out.push_back(FrameOutput(iFrame, currPitch, stateKind));
}
return(out);
}