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 "CepstralPitchTracker.h"

#include "vamp-sdk/FFT.h"

#include <vector>

#include <algorithm>

#include <cstdio>

#include <cmath>

#include <complex>

using std::string;

using std::vector;

using Vamp::RealTime;

CepstralPitchTracker::CepstralPitchTracker(float inputSampleRate) :

    Plugin(inputSampleRate),

    m_channels(0),

    m_stepSize(256),

    m_blockSize(1024),

    m_fmin(50),

    m_fmax(900),

    m_vflen(1),

    m_binFrom(0),

    m_binTo(0),

    m_bins(0)

{

}

CepstralPitchTracker::~CepstralPitchTracker()

{

}

string

CepstralPitchTracker::getIdentifier() const

{

    return "cepstral-pitchtracker";

}

string

CepstralPitchTracker::getName() const

{

    return "Cepstral Pitch Tracker";

}

string

CepstralPitchTracker::getDescription() const

{

    return "Estimate f0 of monophonic material using a cepstrum method.";

}

string

CepstralPitchTracker::getMaker() const

{

    return "Chris Cannam";

}

int

CepstralPitchTracker::getPluginVersion() const

{

    // Increment this each time you release a version that behaves

    // differently from the previous one

    return 1;

}

string

CepstralPitchTracker::getCopyright() const

{

    return "Freely redistributable (BSD license)";

}

CepstralPitchTracker::InputDomain

CepstralPitchTracker::getInputDomain() const

{

    return FrequencyDomain;

}

size_t

CepstralPitchTracker::getPreferredBlockSize() const

{

    return 1024;

}

size_t

CepstralPitchTracker::getPreferredStepSize() const

{

    return 256;

}

size_t

CepstralPitchTracker::getMinChannelCount() const

{

    return 1;

}

size_t

CepstralPitchTracker::getMaxChannelCount() const

{

    return 1;

}

CepstralPitchTracker::ParameterList

CepstralPitchTracker::getParameterDescriptors() const

{

    ParameterList list;

    return list;

}

float

CepstralPitchTracker::getParameter(string identifier) const

{

    return 0.f;

}

void

CepstralPitchTracker::setParameter(string identifier, float value)

{

}

CepstralPitchTracker::ProgramList

CepstralPitchTracker::getPrograms() const

{

    ProgramList list;

    return list;

}

string

CepstralPitchTracker::getCurrentProgram() const

{

    return ""; // no programs

}

void

CepstralPitchTracker::selectProgram(string name)

{

}

CepstralPitchTracker::OutputList

CepstralPitchTracker::getOutputDescriptors() const

{

    OutputList outputs;

    OutputDescriptor d;

    d.identifier = "f0";

    d.name = "Estimated f0";

    d.description = "Estimated fundamental frequency";

    d.unit = "Hz";

    d.hasFixedBinCount = true;

    d.binCount = 1;

    d.hasKnownExtents = true;

    d.minValue = m_fmin;

    d.maxValue = m_fmax;

    d.isQuantized = false;

    d.sampleType = OutputDescriptor::FixedSampleRate;

    d.sampleRate = (m_inputSampleRate / m_stepSize);

    d.hasDuration = false;

    outputs.push_back(d);

    d.identifier = "notes";

    d.name = "Notes";

    d.description = "Derived fixed-pitch note frequencies";

    d.unit = "Hz";

    d.hasFixedBinCount = true;

    d.binCount = 1;

    d.hasKnownExtents = true;

    d.minValue = m_fmin;

    d.maxValue = m_fmax;

    d.isQuantized = false;

    d.sampleType = OutputDescriptor::FixedSampleRate;

    d.sampleRate = (m_inputSampleRate / m_stepSize);

    d.hasDuration = true;

    outputs.push_back(d);

    return outputs;

}

bool

CepstralPitchTracker::initialise(size_t channels, size_t stepSize, size_t blockSize)

{

    if (channels < getMinChannelCount() ||

        channels > getMaxChannelCount()) return false;

//    std::cerr << "CepstralPitchTracker::initialise: channels = " << channels

//              << ", stepSize = " << stepSize << ", blockSize = " << blockSize

//              << std::endl;

    m_channels = channels;

    m_stepSize = stepSize;

    m_blockSize = blockSize;

    m_binFrom = int(m_inputSampleRate / m_fmax);

    m_binTo = int(m_inputSampleRate / m_fmin);

    if (m_binTo >= (int)m_blockSize / 2) {

        m_binTo = m_blockSize / 2 - 1;

    }

    m_bins = (m_binTo - m_binFrom) + 1;

    reset();

    return true;

}

void

CepstralPitchTracker::reset()

{

}

void

CepstralPitchTracker::addFeaturesFrom(NoteHypothesis h, FeatureSet &fs)

{

    NoteHypothesis::Estimates es = h.getAcceptedEstimates();

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

        Feature f;

        f.hasTimestamp = true;

        f.timestamp = es[i].time;

        f.values.push_back(es[i].freq);

        fs[0].push_back(f);

    }

    Feature nf;

    nf.hasTimestamp = true;

    nf.hasDuration = true;

    NoteHypothesis::Note n = h.getAveragedNote();

    nf.timestamp = n.time;

    nf.duration = n.duration;

    nf.values.push_back(n.freq);

    fs[1].push_back(nf);

}

void

CepstralPitchTracker::filter(const double *cep, double *data)

{

    for (int i = 0; i < m_bins; ++i) {

        double v = 0;

        int n = 0;

        // average according to the vertical filter length

        for (int j = -m_vflen/2; j <= m_vflen/2; ++j) {

            int ix = i + m_binFrom + j;

            if (ix >= 0 && ix < (int)m_blockSize) {

                v += cep[ix];

                ++n;

            }

        }

        data[i] = v / n;

    }

}

double

CepstralPitchTracker::cubicInterpolate(const double y[4], double x)

{

    double a0 = y[3] - y[2] - y[0] + y[1];

    double a1 = y[0] - y[1] - a0;

    double a2 = y[2] - y[0];

    double a3 = y[1];

    return

        a0 * x * x * x +

        a1 * x * x +

        a2 * x +

        a3;

}

double

CepstralPitchTracker::findInterpolatedPeak(const double *in, int maxbin)

{

    if (maxbin < 2 || maxbin > m_bins - 3) {

        return maxbin;

    }

    double maxval = 0.0;

    double maxidx = maxbin;

    const int divisions = 10;

    double y[4];

    y[0] = in[maxbin-1];

    y[1] = in[maxbin];

    y[2] = in[maxbin+1];

    y[3] = in[maxbin+2];

    for (int i = 0; i < divisions; ++i) {

        double probe = double(i) / double(divisions);

        double value = cubicInterpolate(y, probe);

        if (value > maxval) {

            maxval = value;

            maxidx = maxbin + probe;

        }

    }

    y[3] = y[2];

    y[2] = y[1];

    y[1] = y[0];

    y[0] = in[maxbin-2];

    for (int i = 0; i < divisions; ++i) {

        double probe = double(i) / double(divisions);

        double value = cubicInterpolate(y, probe);

        if (value > maxval) {

            maxval = value;

            maxidx = maxbin - 1 + probe;

        }

    }

/*

    std::cerr << "centre = " << maxbin << ": ["

              << in[maxbin-2] << ","

              << in[maxbin-1] << ","

              << in[maxbin] << ","

              << in[maxbin+1] << ","

              << in[maxbin+2] << "] -> " << maxidx << std::endl;

*/

    return maxidx;

}

CepstralPitchTracker::FeatureSet

CepstralPitchTracker::process(const float *const *inputBuffers, RealTime timestamp)

{

    FeatureSet fs;

    int bs = m_blockSize;

    int hs = m_blockSize/2 + 1;

    double *rawcep = new double[bs];

    double *io = new double[bs];

    double *logmag = new double[bs];

    // The "inverse symmetric" method. Seems to be the most reliable

    double magmean = 0.0;

    for (int i = 0; i < hs; ++i) {

        double power =

            inputBuffers[0][i*2  ] * inputBuffers[0][i*2  ] +

            inputBuffers[0][i*2+1] * inputBuffers[0][i*2+1];

        double mag = sqrt(power);

        magmean += mag;

        double lm = log(mag + 0.00000001);

        logmag[i] = lm;

        if (i > 0) logmag[bs - i] = lm;

    }

    magmean /= hs;

    double threshold = 0.1; // for magmean

    Vamp::FFT::inverse(bs, logmag, 0, rawcep, io);

    delete[] logmag;

    delete[] io;

    int n = m_bins;

    double *data = new double[n];

    filter(rawcep, data);

    delete[] rawcep;

    double maxval = 0.0;

    int maxbin = -1;

    for (int i = 0; i < n; ++i) {

        if (data[i] > maxval) {

            maxval = data[i];

            maxbin = i;

        }

    }

    if (maxbin < 0) {

        delete[] data;

        return fs;

    }

    double nextPeakVal = 0.0;

    for (int i = 1; i+1 < n; ++i) {

        if (data[i] > data[i-1] &&

            data[i] > data[i+1] &&

            i != maxbin &&

            data[i] > nextPeakVal) {

            nextPeakVal = data[i];

        }

    }

    double cimax = findInterpolatedPeak(data, maxbin);

    double peakfreq = m_inputSampleRate / (cimax + m_binFrom);

    double confidence = 0.0;

    if (nextPeakVal != 0.0) {

        confidence = (maxval - nextPeakVal) * 10.0;

        if (magmean < threshold) confidence = 0.0;

//        std::cerr << "magmean = " << magmean << ", confidence = " << confidence << std::endl;

    }

    NoteHypothesis::Estimate e;

    e.freq = peakfreq;

    e.time = timestamp;

    e.confidence = confidence;

    if (!m_good.accept(e)) {

        int candidate = -1;

        bool accepted = false;

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

            if (m_possible[i].accept(e)) {

                if (m_possible[i].getState() == NoteHypothesis::Satisfied) {

                    accepted = true;

                    candidate = i;

                }

                break;

            }

        }

        if (!accepted) {

            NoteHypothesis h;

            h.accept(e); //!!! must succeed as h is new, so perhaps there should be a ctor for this

            m_possible.push_back(h);

        }

        if (m_good.getState() == NoteHypothesis::Expired) {

            addFeaturesFrom(m_good, fs);

        }

        if (m_good.getState() == NoteHypothesis::Expired ||

            m_good.getState() == NoteHypothesis::Rejected) {

            if (candidate >= 0) {

                m_good = m_possible[candidate];

            } else {

                m_good = NoteHypothesis();

            }

        }

        // reap rejected/expired hypotheses from possible list

        Hypotheses toReap = m_possible;

        m_possible.clear();

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

            NoteHypothesis h = toReap[i];

            if (h.getState() != NoteHypothesis::Rejected &&

                h.getState() != NoteHypothesis::Expired) {

                m_possible.push_back(h);

            }

        }

    }

    delete[] data;

    return fs;

}

CepstralPitchTracker::FeatureSet

CepstralPitchTracker::getRemainingFeatures()

{

    FeatureSet fs;

    if (m_good.getState() == NoteHypothesis::Satisfied) {

        addFeaturesFrom(m_good, fs);

    }

    return fs;

}