106 lines
2.7 KiB
C
106 lines
2.7 KiB
C
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/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*- vi:set ts=8 sts=4 sw=4: */
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/*
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QM DSP library
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Centre for Digital Music, Queen Mary, University of London.
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License as
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published by the Free Software Foundation; either version 2 of the
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License, or (at your option) any later version. See the file
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COPYING included with this distribution for more information.
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*/
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#ifndef KAISER_WINDOW_H
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#define KAISER_WINDOW_H
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#include <vector>
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#include <cmath>
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/**
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* Kaiser window: A windower whose bandwidth and sidelobe height
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* (signal-noise ratio) can be specified. These parameters are traded
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* off against the window length.
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*/
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class KaiserWindow
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{
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public:
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struct Parameters {
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int length;
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double beta;
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};
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/**
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* Construct a Kaiser windower with the given length and beta
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* parameter.
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*/
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KaiserWindow(Parameters p) : m_length(p.length), m_beta(p.beta) { init(); }
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/**
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* Construct a Kaiser windower with the given attenuation in dB
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* and transition width in samples.
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*/
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static KaiserWindow byTransitionWidth(double attenuation,
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double transition) {
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return KaiserWindow
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(parametersForTransitionWidth(attenuation, transition));
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}
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/**
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* Construct a Kaiser windower with the given attenuation in dB
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* and transition bandwidth in Hz for the given samplerate.
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*/
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static KaiserWindow byBandwidth(double attenuation,
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double bandwidth,
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double samplerate) {
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return KaiserWindow
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(parametersForBandwidth(attenuation, bandwidth, samplerate));
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}
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/**
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* Obtain the parameters necessary for a Kaiser window of the
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* given attenuation in dB and transition width in samples.
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*/
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static Parameters parametersForTransitionWidth(double attenuation,
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double transition);
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/**
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* Obtain the parameters necessary for a Kaiser window of the
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* given attenuation in dB and transition bandwidth in Hz for the
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* given samplerate.
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*/
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static Parameters parametersForBandwidth(double attenuation,
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double bandwidth,
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double samplerate) {
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return parametersForTransitionWidth
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(attenuation, (bandwidth * 2 * M_PI) / samplerate);
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}
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int getLength() const {
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return m_length;
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}
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const double *getWindow() const {
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return m_window.data();
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}
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void cut(double *src) const {
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cut(src, src);
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}
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void cut(const double *src, double *dst) const {
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for (int i = 0; i < m_length; ++i) {
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dst[i] = src[i] * m_window[i];
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}
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}
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private:
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int m_length;
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double m_beta;
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std::vector<double> m_window;
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void init();
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};
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#endif
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