diff dsp/chromagram/ConstantQ.cpp @ 225:49844bc8a895

* Queen Mary C++ DSP library

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dsp/chromagram/ConstantQ.cpp	Wed Apr 05 17:35:59 2006 +0000
@@ -0,0 +1,193 @@
+/* -*- 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 "ConstantQ.h"
+#include "dsp/transforms/FFT.h"
+
+//---------------------------------------------------------------------------
+// nextpow2 returns the smallest integer n such that 2^n >= x.
+static double nextpow2(double x) {
+    double y = ceil(log(x)/log(2.0));
+    return(y);
+}
+
+static double squaredModule(const double & xx, const double & yy) {
+    return xx*xx + yy*yy;
+}
+
+//----------------------------------------------------------------------------
+
+ConstantQ::ConstantQ( CQConfig Config ) 
+{
+    initialise( Config );
+}
+
+ConstantQ::~ConstantQ()
+{
+    deInitialise();
+}
+
+//----------------------------------------------------------------------------
+void ConstantQ::sparsekernel()
+{
+    //generates spectral kernel matrix (upside down?)
+    // initialise temporal kernel with zeros, twice length to deal w. complex numbers
+
+    double* hammingWindowRe = new double [ m_FFTLength ];
+    double* hammingWindowIm = new double [ m_FFTLength ];
+    double* transfHammingWindowRe = new double [ m_FFTLength ];
+    double* transfHammingWindowIm = new double [ m_FFTLength ];
+
+    for (unsigned u=0; u < m_FFTLength; u++) 
+    {
+	hammingWindowRe[u] = 0;
+	hammingWindowIm[u] = 0;
+    }
+
+
+    // Here, fftleng*2 is a guess of the number of sparse cells in the matrix
+    // The matrix K x fftlength but the non-zero cells are an antialiased
+    // square root function. So mostly is a line, with some grey point.
+    m_sparseKernelIs.reserve( m_FFTLength*2 );
+    m_sparseKernelJs.reserve( m_FFTLength*2 );
+    m_sparseKernelRealValues.reserve( m_FFTLength*2 );
+    m_sparseKernelImagValues.reserve( m_FFTLength*2 );
+	
+    // for each bin value K, calculate temporal kernel, take its fft to
+    //calculate the spectral kernel then threshold it to make it sparse and 
+    //add it to the sparse kernels matrix
+    double squareThreshold = m_CQThresh * m_CQThresh;
+
+    FFT m_FFT;
+	
+    for (unsigned k = m_uK; k--; ) 
+    {
+	// Computing a hamming window
+	const unsigned hammingLength = (int) ceil( m_dQ * m_FS / ( m_FMin * pow(2,((double)(k))/(double)m_BPO)));
+	for (unsigned i=0; i<hammingLength; i++) 
+	{
+	    const double angle = 2*PI*m_dQ*i/hammingLength;
+	    const double real = cos(angle);
+	    const double imag = sin(angle);
+	    const double absol = hamming(hammingLength, i)/hammingLength;
+	    hammingWindowRe[ i ] = absol*real;
+	    hammingWindowIm[ i ] = absol*imag;
+	}
+
+	//do fft of hammingWindow
+	m_FFT.process( m_FFTLength, 0, hammingWindowRe, hammingWindowIm, transfHammingWindowRe, transfHammingWindowIm );
+
+		
+	for (unsigned j=0; j<( m_FFTLength ); j++) 
+	{
+	    // perform thresholding
+	    const double squaredBin = squaredModule( transfHammingWindowRe[ j ], transfHammingWindowIm[ j ]);
+	    if (squaredBin <= squareThreshold) continue;
+		
+	    // Insert non-zero position indexes, doubled because they are floats
+	    m_sparseKernelIs.push_back(j);
+	    m_sparseKernelJs.push_back(k);
+
+	    // take conjugate, normalise and add to array sparkernel
+	    m_sparseKernelRealValues.push_back( transfHammingWindowRe[ j ]/m_FFTLength);
+	    m_sparseKernelImagValues.push_back(-transfHammingWindowIm[ j ]/m_FFTLength);
+	}
+
+    }
+
+    delete [] hammingWindowRe;
+    delete [] hammingWindowIm;
+    delete [] transfHammingWindowRe;
+    delete [] transfHammingWindowIm;
+
+}
+
+//-----------------------------------------------------------------------------
+double* ConstantQ::process( double* fftdata )
+{
+    for (unsigned row=0; row<2*m_uK; row++) 
+    {
+	m_CQdata[ row ] = 0;
+	m_CQdata[ row+1 ] = 0;
+    }
+    const unsigned *fftbin = &(m_sparseKernelIs[0]);
+    const unsigned *cqbin  = &(m_sparseKernelJs[0]);
+    const double   *real   = &(m_sparseKernelRealValues[0]);
+    const double   *imag   = &(m_sparseKernelImagValues[0]);
+    const unsigned int sparseCells = m_sparseKernelRealValues.size();
+	
+    for (unsigned i = 0; i<sparseCells; i++)
+    {
+	const unsigned row = cqbin[i];
+	const unsigned col = fftbin[i];
+	const double & r1  = real[i];
+	const double & i1  = imag[i];
+	const double & r2  = fftdata[ (2*m_FFTLength) - 2*col];
+	const double & i2  = fftdata[ (2*m_FFTLength) - 2*col+1];
+	// add the multiplication
+	m_CQdata[ 2*row  ] += (r1*r2 - i1*i2);
+	m_CQdata[ 2*row+1] += (r1*i2 + i1*r2);
+    }
+
+    return m_CQdata;
+}
+
+
+void ConstantQ::initialise( CQConfig Config )
+{
+    m_FS = Config.FS;
+    m_FMin = Config.min;		// min freq
+    m_FMax = Config.max;		// max freq
+    m_BPO = Config.BPO;		// bins per octave
+    m_CQThresh = Config.CQThresh;// ConstantQ threshold for kernel generation
+
+    m_dQ = 1/(pow(2,(1/(double)m_BPO))-1);	// Work out Q value for Filter bank
+    m_uK = (unsigned int) ceil(m_BPO * log(m_FMax/m_FMin)/log(2.0));	// No. of constant Q bins
+
+    // work out length of fft required for this constant Q Filter bank
+    m_FFTLength = (int) pow(2, nextpow2(ceil( m_dQ*m_FS/m_FMin )));
+
+    m_hop = m_FFTLength/8; // <------ hop size is window length divided by 32
+
+    // allocate memory for cqdata
+    m_CQdata = new double [2*m_uK];
+}
+
+void ConstantQ::deInitialise()
+{
+    delete [] m_CQdata;
+}
+
+void ConstantQ::process(double *FFTRe, double* FFTIm, double *CQRe, double *CQIm)
+{
+    for (unsigned row=0; row<m_uK; row++) 
+    {
+	CQRe[ row ] = 0;
+	CQIm[ row ] = 0;
+    }
+
+    const unsigned *fftbin = &(m_sparseKernelIs[0]);
+    const unsigned *cqbin  = &(m_sparseKernelJs[0]);
+    const double   *real   = &(m_sparseKernelRealValues[0]);
+    const double   *imag   = &(m_sparseKernelImagValues[0]);
+    const unsigned int sparseCells = m_sparseKernelRealValues.size();
+	
+    for (unsigned i = 0; i<sparseCells; i++)
+    {
+	const unsigned row = cqbin[i];
+	const unsigned col = fftbin[i];
+	const double & r1  = real[i];
+	const double & i1  = imag[i];
+	const double & r2  = FFTRe[ m_FFTLength- col];
+	const double & i2  = FFTIm[ m_FFTLength - col];
+	// add the multiplication
+	CQRe[ row ] += (r1*r2 - i1*i2);
+	CQIm[ row ] += (r1*i2 + i1*r2);
+    }
+}