annotate examples/PowerSpectrum.cpp @ 246:5bfed156b45d

* 3 * lag is not related in 4/4, is it?

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

/*
    Vamp

    An API for audio analysis and feature extraction plugins.

    Centre for Digital Music, Queen Mary, University of London.
    Copyright 2008 QMUL.
  
    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
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    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
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    WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

    Except as contained in this notice, the names of the Centre for
    Digital Music; Queen Mary, University of London; and Chris Cannam
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*/

#include "PowerSpectrum.h"

using std::string;
using std::cerr;
using std::endl;

#include <math.h>

PowerSpectrum::PowerSpectrum(float inputSampleRate) :
    Plugin(inputSampleRate),
    m_blockSize(0)
{
}

PowerSpectrum::~PowerSpectrum()
{
}

string
PowerSpectrum::getIdentifier() const
{
    return "powerspectrum";
}

string
PowerSpectrum::getName() const
{
    return "Simple Power Spectrum";
}

string
PowerSpectrum::getDescription() const
{
    return "Return the power spectrum of a signal";
}

string
PowerSpectrum::getMaker() const
{
    return "Vamp SDK Example Plugins";
}

int
PowerSpectrum::getPluginVersion() const
{
    return 1;
}

string
PowerSpectrum::getCopyright() const
{
    return "Freely redistributable (BSD license)";
}

bool
PowerSpectrum::initialise(size_t channels, size_t stepSize, size_t blockSize)
{
    if (channels < getMinChannelCount() ||
	channels > getMaxChannelCount()) return false;

    m_blockSize = blockSize;

    return true;
}

void
PowerSpectrum::reset()
{
}

PowerSpectrum::OutputList
PowerSpectrum::getOutputDescriptors() const
{
    OutputList list;

    OutputDescriptor d;
    d.identifier = "powerspectrum";
    d.name = "Power Spectrum";
    d.description = "Power values of the frequency spectrum bins calculated from the input signal";
    d.unit = "";
    d.hasFixedBinCount = true;
    d.binCount = m_blockSize / 2 + 1;
    d.hasKnownExtents = false;
    d.isQuantized = false;
    d.sampleType = OutputDescriptor::OneSamplePerStep;
    list.push_back(d);

    return list;
}

PowerSpectrum::FeatureSet
PowerSpectrum::process(const float *const *inputBuffers, Vamp::RealTime timestamp)
{
    FeatureSet fs;

    if (m_blockSize == 0) {
	cerr << "ERROR: PowerSpectrum::process: Not initialised" << endl;
	return fs;
    }

    size_t n = m_blockSize / 2 + 1;
    const float *fbuf = inputBuffers[0];

    Feature feature;
    feature.hasTimestamp = false;
    feature.values.reserve(n); // optional

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

	double real = fbuf[i * 2];
	double imag = fbuf[i * 2 + 1];

        feature.values.push_back(real * real + imag * imag);
    }

    fs[0].push_back(feature);

    return fs;
}

PowerSpectrum::FeatureSet
PowerSpectrum::getRemainingFeatures()
{
    return FeatureSet();
}