Chris@124: /* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */
Chris@124: 
Chris@124: /*
Chris@124:     QM DSP library
Chris@124:     Centre for Digital Music, Queen Mary, University of London.
Chris@124:  
Chris@124:     This program is free software; you can redistribute it and/or
Chris@124:     modify it under the terms of the GNU General Public License as
Chris@124:     published by the Free Software Foundation; either version 2 of the
Chris@124:     License, or (at your option) any later version.  See the file
Chris@124:     COPYING included with this distribution for more information.
Chris@124: */
Chris@124: 
Chris@124: #ifndef KAISER_WINDOW_H
Chris@124: #define KAISER_WINDOW_H
Chris@124: 
Chris@124: #include <vector>
Chris@124: #include <cmath>
Chris@124: 
Chris@124: class KaiserWindow
Chris@124: {
Chris@124: public:
Chris@124:     struct Parameters {
Chris@124: 	int length;
Chris@124: 	double beta;
Chris@124:     };
Chris@124: 
Chris@124:     /**
Chris@124:      * Construct a Kaiser windower with the given length and beta
Chris@124:      * parameter.
Chris@124:      */
Chris@124:     KaiserWindow(Parameters p) : m_length(p.length), m_beta(p.beta) { init(); }
Chris@124: 
Chris@124:     /**
Chris@124:      * Construct a Kaiser windower with the given attenuation in dB
Chris@124:      * and transition width in samples.
Chris@124:      */
Chris@124:     static KaiserWindow byTransitionWidth(double attenuation,
Chris@124: 					  double transition) {
Chris@124: 	return KaiserWindow
Chris@124: 	    (parametersForTransitionWidth(attenuation, transition));
Chris@124:     }
Chris@124: 
Chris@124:     /**
Chris@124:      * Construct a Kaiser windower with the given attenuation in dB
Chris@124:      * and transition bandwidth in Hz for the given samplerate.
Chris@124:      */
Chris@124:     static KaiserWindow byBandwidth(double attenuation,
Chris@124: 				    double bandwidth,
Chris@124: 				    double samplerate) {
Chris@124: 	return KaiserWindow
Chris@124: 	    (parametersForBandwidth(attenuation, bandwidth, samplerate));
Chris@124:     }
Chris@124: 
Chris@124:     /**
Chris@124:      * Obtain the parameters necessary for a Kaiser window of the
Chris@124:      * given attenuation in dB and transition width in samples.
Chris@124:      */
Chris@124:     static Parameters parametersForTransitionWidth(double attenuation,
Chris@124: 						   double transition);
Chris@124: 
Chris@124:     /**
Chris@124:      * Obtain the parameters necessary for a Kaiser window of the
Chris@124:      * given attenuation in dB and transition bandwidth in Hz for the
Chris@124:      * given samplerate.
Chris@124:      */
Chris@124:     static Parameters parametersForBandwidth(double attenuation,
Chris@124: 					     double bandwidth,
Chris@124: 					     double samplerate) {
Chris@124: 	return parametersForTransitionWidth
Chris@124: 	    (attenuation, (bandwidth * 2 * M_PI) / samplerate);
Chris@124:     } 
Chris@124: 
Chris@124:     int getLength() const {
Chris@124: 	return m_length;
Chris@124:     }
Chris@124: 
Chris@124:     const double *getWindow() const { 
Chris@124: 	return m_window.data();
Chris@124:     }
Chris@124: 
Chris@124:     void cut(double *src) const { 
Chris@124: 	cut(src, src); 
Chris@124:     }
Chris@124: 
Chris@124:     void cut(const double *src, double *dst) const {
Chris@124: 	for (int i = 0; i < m_length; ++i) {
Chris@124: 	    dst[i] = src[i] * m_window[i];
Chris@124: 	}
Chris@124:     }
Chris@124: 
Chris@124: private:
Chris@124:     int m_length;
Chris@124:     double m_beta;
Chris@124:     std::vector<double> m_window;
Chris@124: 
Chris@124:     void init();
Chris@124: };
Chris@124: 
Chris@124: #endif