Cepstral Pitch Tracker

/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */

/*

    This file is Copyright (c) 2012 Chris Cannam

    Permission is hereby granted, free of charge, to any person

    obtaining a copy of this software and associated documentation

    files (the "Software"), to deal in the Software without

    restriction, including without limitation the rights to use, copy,

    modify, merge, publish, distribute, sublicense, and/or sell copies

    of the Software, and to permit persons to whom the Software is

    furnished to do so, subject to the following conditions:

    The above copyright notice and this permission notice shall be

    included in all copies or substantial portions of the Software.

    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,

    EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF

    MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND

    NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR

    ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF

    CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION

    WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

*/

#include "NoteHypothesis.h"

#include <cmath>

using Vamp::RealTime;

NoteHypothesis::NoteHypothesis()

{

    m_state = New;

}

NoteHypothesis::~NoteHypothesis()

{

}

bool

NoteHypothesis::isWithinTolerance(Estimate s) const

{

    if (m_pending.empty()) {

        return true;

    }

    // check we are within a relatively close tolerance of the last

    // candidate

    Estimate last = m_pending[m_pending.size()-1];

    double r = s.freq / last.freq;

    int cents = lrint(1200.0 * (log(r) / log(2.0)));

    if (cents < -60 || cents > 60) return false;

    // and within a slightly bigger tolerance of the current mean

    double meanFreq = getMeanFrequency();

    r = s.freq / meanFreq;

    cents = lrint(1200.0 * (log(r) / log(2.0)));

    if (cents < -80 || cents > 80) return false;

    return true;

}

bool

NoteHypothesis::isOutOfDateFor(Estimate s) const

{

    if (m_pending.empty()) return false;

    return ((s.time - m_pending[m_pending.size()-1].time) > 

            RealTime::fromMilliseconds(40));

}

bool 

NoteHypothesis::isSatisfied() const

{

    if (m_pending.empty()) return false;

    double meanConfidence = 0.0;

    for (int i = 0; i < (int)m_pending.size(); ++i) {

        meanConfidence += m_pending[i].confidence;

    }

    meanConfidence /= m_pending.size();

    int lengthRequired = 100;

    if (meanConfidence > 0.0) {

        lengthRequired = int(2.0 / meanConfidence + 0.5);

    }

    return ((int)m_pending.size() > lengthRequired);

}

bool

NoteHypothesis::accept(Estimate s)

{

    bool accept = false;

    static double negligibleConfidence = 0.0001;

    if (s.confidence < negligibleConfidence) {

        // avoid piling up a lengthy sequence of estimates that are

        // all acceptable but are in total not enough to cause us to

        // be satisfied

        m_state = Rejected;

        return false;

    }

    switch (m_state) {

    case New:

        m_state = Provisional;

        accept = true;

        break;

    case Provisional:

        if (isOutOfDateFor(s)) {

            m_state = Rejected;

        } else if (isWithinTolerance(s)) {

            accept = true;

        }

        break;

    case Satisfied:

        if (isOutOfDateFor(s)) {

            m_state = Expired;

        } else if (isWithinTolerance(s)) {

            accept = true;

        }

        break;

    case Rejected:

        break;

    case Expired:

        break;

    }

    if (accept) {

        m_pending.push_back(s);

        if (m_state == Provisional && isSatisfied()) {

            m_state = Satisfied;

        }

    }

    return accept;

}        

NoteHypothesis::State

NoteHypothesis::getState() const

{

    return m_state;

}

NoteHypothesis::Estimates

NoteHypothesis::getAcceptedEstimates() const

{

    if (m_state == Satisfied || m_state == Expired) {

        return m_pending;

    } else {

        return Estimates();

    }

}

RealTime

NoteHypothesis::getStartTime() const

{

    if (!(m_state == Satisfied || m_state == Expired)) {

        return RealTime::zeroTime;

    } else {

        return m_pending.begin()->time;

    }

}

double

NoteHypothesis::getMeanFrequency() const

{

    double acc = 0.0;

    if (m_pending.empty()) return acc;

    for (int i = 0; i < (int)m_pending.size(); ++i) {

        acc += m_pending[i].freq;

    }

    acc /= m_pending.size();

    return acc;

}

NoteHypothesis::Note

NoteHypothesis::getAveragedNote() const

{

    Note n;

    if (!(m_state == Satisfied || m_state == Expired)) {

        n.freq = 0.0;

        n.time = RealTime::zeroTime;

        n.duration = RealTime::zeroTime;

        return n;

    }

    n.time = m_pending.begin()->time;

    Estimates::const_iterator i = m_pending.end();

    --i;

    n.duration = i->time - n.time;

    // just mean frequency for now, but this isn't at all right perceptually

    n.freq = getMeanFrequency();

    return n;

}