annotate dsp/chromagram/Chromagram.cpp @ 73:dcb555b90924

* Key detector: when returning key strengths, use the peak value of the
  three underlying chromagram correlations (from 36-bin chromagram)
  corresponding to each key, instead of the mean.
  Rationale: This is the same method as used when returning the key value,
  and it's nice to have the same results in both returned value and plot.
  The peak performed better than the sum with a simple test set of triads,
  so it seems reasonable to change the plot to match the key output rather
  than the other way around.

* FFT: kiss_fftr returns only the non-conjugate bins, synthesise the rest
  rather than leaving them (perhaps dangerously) undefined.  Fixes an
  uninitialised data error in chromagram that could cause garbage results
  from key detector.

* Constant Q: remove precalculated values again, I reckon they're not
  proving such a good tradeoff.

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

/*
    QM DSP Library

    Centre for Digital Music, Queen Mary, University of London.
    This file copyright 2005-2006 Christian Landone.
    All rights reserved.
*/

#include <iostream>
#include <cmath>
#include "maths/MathUtilities.h"
#include "Chromagram.h"

//----------------------------------------------------------------------------

Chromagram::Chromagram( ChromaConfig Config ) :
    m_skGenerated(false)
{
    initialise( Config );
}

int Chromagram::initialise( ChromaConfig Config )
{	
    m_FMin = Config.min;		// min freq
    m_FMax = Config.max;		// max freq
    m_BPO  = Config.BPO;		// bins per octave
    m_normalise = Config.normalise;     // if frame normalisation is required

    // No. of constant Q bins
    m_uK = ( unsigned int ) ceil( m_BPO * log(m_FMax/m_FMin)/log(2.0));	

    // Create array for chroma result
    m_chromadata = new double[ m_BPO ];

    // Create Config Structure for ConstantQ operator
    CQConfig ConstantQConfig;

    // Populate CQ config structure with parameters
    // inherited from the Chroma config
    ConstantQConfig.FS	 = Config.FS;
    ConstantQConfig.min = m_FMin;
    ConstantQConfig.max = m_FMax;
    ConstantQConfig.BPO = m_BPO;
    ConstantQConfig.CQThresh = Config.CQThresh;
	
    // Initialise ConstantQ operator
    m_ConstantQ = new ConstantQ( ConstantQConfig );

    // Initialise working arrays
    m_frameSize = m_ConstantQ->getfftlength();
    m_hopSize = m_ConstantQ->gethop();

    // Initialise FFT object	
    m_FFT = new FFTReal(m_frameSize);

    m_FFTRe = new double[ m_frameSize ];
    m_FFTIm = new double[ m_frameSize ];
    m_CQRe  = new double[ m_uK ];
    m_CQIm  = new double[ m_uK ];

    m_window = 0;
    m_windowbuf = 0;

    return 1;
}

Chromagram::~Chromagram()
{
    deInitialise();
}

int Chromagram::deInitialise()
{
    delete[] m_windowbuf;
    delete m_window;

    delete [] m_chromadata;

    delete m_FFT;

    delete m_ConstantQ;

    delete [] m_FFTRe;
    delete [] m_FFTIm;
    delete [] m_CQRe;
    delete [] m_CQIm;
    return 1;
}

//----------------------------------------------------------------------------------
// returns the absolute value of complex number xx + i*yy
double Chromagram::kabs(double xx, double yy)
{
    double ab = sqrt(xx*xx + yy*yy);
    return(ab);
}
//-----------------------------------------------------------------------------------


void Chromagram::unityNormalise(double *src)
{
    double min, max;

    double val = 0;

    MathUtilities::getFrameMinMax( src, m_BPO, & min, &max );

    for( unsigned int i = 0; i < m_BPO; i++ )
    {
	val = src[ i ] / max;

	src[ i ] = val;
    }
}


double* Chromagram::process( const double *data )
{
    if (!m_skGenerated) {
        // Generate CQ Kernel 
        m_ConstantQ->sparsekernel();
        m_skGenerated = true;
    }

    if (!m_window) {
        m_window = new Window<double>(HammingWindow, m_frameSize);
        m_windowbuf = new double[m_frameSize];
    }

    for (int i = 0; i < m_frameSize; ++i) {
        m_windowbuf[i] = data[i];
    }
    m_window->cut(m_windowbuf);

    // FFT of current frame
    m_FFT->process(false, m_windowbuf, m_FFTRe, m_FFTIm);

    return process(m_FFTRe, m_FFTIm);
}

double* Chromagram::process( const double *real, const double *imag )
{
    if (!m_skGenerated) {
        // Generate CQ Kernel 
        m_ConstantQ->sparsekernel();
        m_skGenerated = true;
    }

    // initialise chromadata to 0
    for (unsigned i = 0; i < m_BPO; i++) m_chromadata[i] = 0;

    double cmax = 0.0;
    double cval = 0;

    // Calculate ConstantQ frame
    m_ConstantQ->process( real, imag, m_CQRe, m_CQIm );
	
    // add each octave of cq data into Chromagram
    const unsigned octaves = (int)floor(double( m_uK/m_BPO))-1;
    for (unsigned octave = 0; octave <= octaves; octave++) 
    {
	unsigned firstBin = octave*m_BPO;
	for (unsigned i = 0; i < m_BPO; i++) 
	{
	    m_chromadata[i] += kabs( m_CQRe[ firstBin + i ], m_CQIm[ firstBin + i ]);
	}
    }

    MathUtilities::normalise(m_chromadata, m_BPO, m_normalise);

    return m_chromadata;
}