C++ Constant-Q

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

/*

    Constant-Q library

    Copyright (c) 2013-2014 Queen Mary, University of London

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    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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*/

#ifndef CQSPECTROGRAM_H

#define CQSPECTROGRAM_H

#include "ConstantQ.h"

/**

 * Calculate a dense constant-Q magnitude spectrogram from time-domain

 * input. The input of each \ref process call is a single frame of

 * time-domain samples; the output is a series of fixed-height

 * columns. See \ref process for details.

 *

 * If you need the full complex-valued constant-Q output, you must use

 * the \ref ConstantQ class instead.

 */

class CQSpectrogram : public CQBase

{

public:

    enum Interpolation {

        /// leave empty cells as zero

        InterpolateZeros,

        /// replace empty cells with a repeat of the previous column

        InterpolateHold,

        /// perform linear interpolation between consecutive time cells

        InterpolateLinear,

    };

    /**

     * Construct a Constant-Q magnitude spectrogram object using the

     * given transform parameters.

     */

    CQSpectrogram(CQParameters params, Interpolation interpolation);

    virtual ~CQSpectrogram();

    // CQBase methods, see CQBase.h for documentation

    virtual bool isValid() const { return m_cq.isValid(); }

    virtual double getSampleRate() const { return m_cq.getSampleRate(); }

    virtual int getBinsPerOctave() const { return m_cq.getBinsPerOctave(); }

    virtual int getOctaves() const { return m_cq.getOctaves(); }

    virtual int getTotalBins() const { return m_cq.getTotalBins(); }

    virtual int getColumnHop() const { return m_cq.getColumnHop(); }

    virtual int getLatency() const { return m_cq.getLatency(); } 

    virtual double getMaxFrequency() const { return m_cq.getMaxFrequency(); }

    virtual double getMinFrequency() const { return m_cq.getMinFrequency(); }

    virtual double getBinFrequency(double bin) const { return m_cq.getBinFrequency(bin); }

    /**

     * Given a series of time-domain samples, return a series of

     * constant-Q magnitude columns. Any samples left over (that did

     * not fit into a constant-Q processing block) are saved for the

     * next call to process or getRemainingBlocks.

     *

     * The input is assumed to be a single frame of time-domain sample

     * values, such that consecutive calls to \ref process receive

     * contiguous frames from the source signal. Each frame may be of

     * any length in samples.

     *

     * Each output column contains a series of constant-Q bin value

     * magnitudes, ordered from highest to lowest frequency.

     *  

     * The columns are all of the same height, but they might not all

     * be populated, depending on the interpolation mode: in

     * InterpolateZeros mode, the lower octaves (which are spaced more

     * widely in the raw constant-Q than the highest octave) will

     * contain zeros for the undefined values, but in the other

     * interpolation modes every cell will be filled.

     *

     * To obtain raw, complex constant-Q bin values, use the ConstantQ

     * class.

     */

    RealBlock process(const RealSequence &);

    /**

     * Return the remaining constant-Q magnitude columns following the

     * end of processing. Any buffered input is padded so as to ensure

     * that all input provided to process() will have been returned.

     */

    RealBlock getRemainingOutput();

private:

    ConstantQ m_cq;

    Interpolation m_interpolation;

    RealBlock m_buffer;

    RealBlock postProcess(const ComplexBlock &, bool insist);

    RealBlock fetchHold(bool insist);

    RealBlock fetchLinear(bool insist);

    RealBlock linearInterpolated(const RealBlock &, int, int);

    RealColumn m_prevColumn;

    // Not provided (because ConstantQ isn't copyable)

    CQSpectrogram(const CQSpectrogram &);

    CQSpectrogram &operator=(const CQSpectrogram &);

};

#endif