Cepstral Pitch Tracker

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

/* Copyright Chris Cannam - All Rights Reserved */

#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 = 10000;

    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;

    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();

    }

}

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;

}