BeatRoot Vamp Plugin

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

/*

  Vamp feature extraction plugin for the BeatRoot beat tracker.

  Centre for Digital Music, Queen Mary, University of London.

  This file copyright 2011 Simon Dixon, Chris Cannam and QMUL.

  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 "Agent.h"

#include "BeatTracker.h"

const double AgentParameters::DEFAULT_POST_MARGIN_FACTOR = 0.3;

const double AgentParameters::DEFAULT_PRE_MARGIN_FACTOR = 0.15;

const double AgentParameters::DEFAULT_MAX_CHANGE = 0.2;

const double AgentParameters::DEFAULT_EXPIRY_TIME = 10.0;

const double Agent::INNER_MARGIN = 0.040;

const double Agent::CONF_FACTOR = 0.5;

const double Agent::DEFAULT_CORRECTION_FACTOR = 50.0;

int Agent::idCounter = 0;

void Agent::accept(Event e, double err, int beats) {

    beatTime = e.time;

    events.push_back(e);

    if (fabs(initialBeatInterval - beatInterval -

             err / correctionFactor) < maxChange * initialBeatInterval)

        beatInterval += err / correctionFactor;// Adjust tempo

    beatCount += beats;

    double conFactor = 1.0 - CONF_FACTOR * err /

        (err>0? postMargin: -preMargin);

    if (decayFactor > 0) {

        double memFactor = 1. - 1. / threshold((double)beatCount,1,decayFactor);

        phaseScore = memFactor * phaseScore +

            (1.0 - memFactor) * conFactor * e.salience;

    } else

        phaseScore += conFactor * e.salience;

#ifdef DEBUG_BEATROOT

    std::cerr << "Ag#" << idNumber << ": " << beatInterval << std::endl;

    std::cerr << "  Beat" << beatCount << "  Time=" << beatTime

              << "  Score=" << tempoScore << ":P" << phaseScore << ":"

              << topScoreTime << std::endl;

#endif

} // accept()

bool Agent::considerAsBeat(Event e, AgentList &a) {

    double err;

    if (beatTime < 0) {        // first event

#ifdef DEBUG_BEATROOT

        std::cerr << "Ag#" << idNumber << ": accepting first event trivially at " << e.time << std::endl;

#endif

        accept(e, 0, 1);

        return true;

    } else {                        // subsequent events

        EventList::iterator last = events.end();

        --last;

        if (e.time - last->time > expiryTime) {

#ifdef DEBUG_BEATROOT

            std::cerr << "Ag#" << idNumber << ": time " << e.time 

                      << " too late relative to " << last->time << " (expiry "

                      << expiryTime << "), giving up" << std::endl;

#endif

            phaseScore = -1.0;        // flag agent to be deleted

            return false;

        }

        double beats = nearbyint((e.time - beatTime) / beatInterval);

        err = e.time - beatTime - beats * beatInterval;

#ifdef DEBUG_BEATROOT

        std::cerr << "Ag#" << idNumber << ": time " << e.time << ", err " << err << " for beats " << beats << std::endl;

#endif

        if ((beats > 0) && (-preMargin <= err) && (err <= postMargin)) {

            if (fabs(err) > innerMargin) {

#ifdef DEBUG_BEATROOT

                std::cerr << "Ag#" << idNumber << ": creating another new agent" << std::endl;

#endif

                // Create new agent that skips this event (avoids

                // large phase jump)

                a.add(clone());

            }

            accept(e, err, (int)beats);

            return true;

        }

    }

    return false;

} // considerAsBeat()

void Agent::fillBeats(double start) {

    double prevBeat = 0, nextBeat, currentInterval, beats;

    EventList::iterator ei = events.begin();

    if (ei != events.end()) {

        EventList::iterator ni = ei;

        if (++ni != events.end()) {

            prevBeat = ni->time;

        }

    }

    while (ei != events.end()) {

        EventList::iterator ni = ei;

        if (ni == events.end() ||

            ++ni == events.end()) {

            break;

        }

        nextBeat = ni->time;

        beats = nearbyint((nextBeat - prevBeat) / beatInterval - 0.01); //prefer slow

        currentInterval = (nextBeat - prevBeat) / beats;

        for ( ; (nextBeat > start) && (beats > 1.5); beats--) {

            prevBeat += currentInterval;

            events.insert(ni, BeatTracker::newBeat(prevBeat, 0));

        }

        prevBeat = nextBeat;

        ei = ni;

    }

} // fillBeats()