annotate dsp/phasevocoder/PhaseVocoder.cpp @ 321:f1e6be2de9a5

A threshold (delta) is added in the peak picking parameters structure (PPickParams). It is used as an offset when computing the smoothed detection function. A constructor for the structure PPickParams is also added to set the parameters to 0 when a structure instance is created. Hence programmes using the peak picking parameter structure and which do not set the delta parameter (e.g. QM Vamp note onset detector) won't be affected by the modifications.

Functions modified:
- dsp/onsets/PeakPicking.cpp
- dsp/onsets/PeakPicking.h
- dsp/signalconditioning/DFProcess.cpp
- dsp/signalconditioning/DFProcess.h

/* -*- 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 2005-2006 Christian Landone.

    This program is free software; you can redistribute it and/or
    modify it under the terms of the GNU General Public License as
    published by the Free Software Foundation; either version 2 of the
    License, or (at your option) any later version.  See the file
    COPYING included with this distribution for more information.
*/

#include "PhaseVocoder.h"
#include "dsp/transforms/FFT.h"
#include <math.h>

//////////////////////////////////////////////////////////////////////
// Construction/Destruction
//////////////////////////////////////////////////////////////////////

PhaseVocoder::PhaseVocoder(unsigned int n) :
    m_n(n)
{
    m_fft = new FFTReal(m_n);
    m_realOut = new double[m_n];
    m_imagOut = new double[m_n];
}

PhaseVocoder::~PhaseVocoder()
{
    delete [] m_realOut;
    delete [] m_imagOut;
    delete m_fft;
}

void PhaseVocoder::FFTShift(unsigned int size, double *src)
{
    const int hs = size/2;
    for (int i = 0; i < hs; ++i) {
        double tmp = src[i];
        src[i] = src[i + hs];
        src[i + hs] = tmp;
    }
}

void PhaseVocoder::process(double *src, double *mag, double *theta)
{
    FFTShift( m_n, src);
	
    m_fft->process(0, src, m_realOut, m_imagOut);

    getMagnitude( m_n/2, mag, m_realOut, m_imagOut);
    getPhase( m_n/2, theta, m_realOut, m_imagOut);
}

void PhaseVocoder::getMagnitude(unsigned int size, double *mag, double *real, double *imag)
{	
    unsigned int j;

    for( j = 0; j < size; j++)
    {
	mag[ j ] = sqrt( real[ j ] * real[ j ] + imag[ j ] * imag[ j ]);
    }
}

void PhaseVocoder::getPhase(unsigned int size, double *theta, double *real, double *imag)
{
    unsigned int k;

    // Phase Angle "matlab" style 
    //Watch out for quadrant mapping  !!!
    for( k = 0; k < size; k++)
    {
	theta[ k ] = atan2( -imag[ k ], real[ k ]);
    }	
}