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/* -*- 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 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.
*/
#ifndef KAISER_WINDOW_H
#define KAISER_WINDOW_H
#include <vector>
#include <cmath>
/**
* Kaiser window: A windower whose bandwidth and sidelobe height
* (signal-noise ratio) can be specified. These parameters are traded
* off against the window length.
*/
class KaiserWindow
{
public:
struct Parameters {
int length;
double beta;
};
/**
* Construct a Kaiser windower with the given length and beta
* parameter.
*/
KaiserWindow(Parameters p) : m_length(p.length), m_beta(p.beta) { init(); }
/**
* Construct a Kaiser windower with the given attenuation in dB
* and transition width in samples.
*/
static KaiserWindow byTransitionWidth(double attenuation,
double transition) {
return KaiserWindow
(parametersForTransitionWidth(attenuation, transition));
}
/**
* Construct a Kaiser windower with the given attenuation in dB
* and transition bandwidth in Hz for the given samplerate.
*/
static KaiserWindow byBandwidth(double attenuation,
double bandwidth,
double samplerate) {
return KaiserWindow
(parametersForBandwidth(attenuation, bandwidth, samplerate));
}
/**
* Obtain the parameters necessary for a Kaiser window of the
* given attenuation in dB and transition width in samples.
*/
static Parameters parametersForTransitionWidth(double attenuation,
double transition);
/**
* Obtain the parameters necessary for a Kaiser window of the
* given attenuation in dB and transition bandwidth in Hz for the
* given samplerate.
*/
static Parameters parametersForBandwidth(double attenuation,
double bandwidth,
double samplerate) {
return parametersForTransitionWidth
(attenuation, (bandwidth * 2 * M_PI) / samplerate);
}
int getLength() const {
return m_length;
}
const double *getWindow() const {
return &m_window[0];
}
void cut(double *src) const {
cut(src, src);
}
void cut(const double *src, double *dst) const {
for (int i = 0; i < m_length; ++i) {
dst[i] = src[i] * m_window[i];
}
}
private:
int m_length;
double m_beta;
std::vector<double> m_window;
void init();
};
#endif
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