Chris@366: /* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */
Chris@366: /*
Chris@366:     Constant-Q library
Chris@366:     Copyright (c) 2013-2014 Queen Mary, University of London
Chris@366: 
Chris@366:     Permission is hereby granted, free of charge, to any person
Chris@366:     obtaining a copy of this software and associated documentation
Chris@366:     files (the "Software"), to deal in the Software without
Chris@366:     restriction, including without limitation the rights to use, copy,
Chris@366:     modify, merge, publish, distribute, sublicense, and/or sell copies
Chris@366:     of the Software, and to permit persons to whom the Software is
Chris@366:     furnished to do so, subject to the following conditions:
Chris@366: 
Chris@366:     The above copyright notice and this permission notice shall be
Chris@366:     included in all copies or substantial portions of the Software.
Chris@366: 
Chris@366:     THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
Chris@366:     EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
Chris@366:     MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
Chris@366:     NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
Chris@366:     CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
Chris@366:     CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
Chris@366:     WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
Chris@366: 
Chris@366:     Except as contained in this notice, the names of the Centre for
Chris@366:     Digital Music; Queen Mary, University of London; and Chris Cannam
Chris@366:     shall not be used in advertising or otherwise to promote the sale,
Chris@366:     use or other dealings in this Software without prior written
Chris@366:     authorization.
Chris@366: */
Chris@366: 
Chris@366: #ifndef KAISER_WINDOW_H
Chris@366: #define KAISER_WINDOW_H
Chris@366: 
Chris@366: #include <vector>
Chris@366: #include <cmath>
Chris@366: 
Chris@366: #include "pi.h"
Chris@366: 
Chris@366: /**
Chris@366:  * Kaiser window: A windower whose bandwidth and sidelobe height
Chris@366:  * (signal-noise ratio) can be specified. These parameters are traded
Chris@366:  * off against the window length.
Chris@366:  */
Chris@366: class KaiserWindow
Chris@366: {
Chris@366: public:
Chris@366:     struct Parameters {
Chris@366: 	int length;
Chris@366: 	double beta;
Chris@366:     };
Chris@366: 
Chris@366:     /**
Chris@366:      * Construct a Kaiser windower with the given length and beta
Chris@366:      * parameter.
Chris@366:      */
Chris@366:     KaiserWindow(Parameters p) : m_length(p.length), m_beta(p.beta) { init(); }
Chris@366: 
Chris@366:     /**
Chris@366:      * Construct a Kaiser windower with the given attenuation in dB
Chris@366:      * and transition width in samples.
Chris@366:      */
Chris@366:     static KaiserWindow byTransitionWidth(double attenuation,
Chris@366: 					  double transition) {
Chris@366: 	return KaiserWindow
Chris@366: 	    (parametersForTransitionWidth(attenuation, transition));
Chris@366:     }
Chris@366: 
Chris@366:     /**
Chris@366:      * Construct a Kaiser windower with the given attenuation in dB
Chris@366:      * and transition bandwidth in Hz for the given samplerate.
Chris@366:      */
Chris@366:     static KaiserWindow byBandwidth(double attenuation,
Chris@366: 				    double bandwidth,
Chris@366: 				    double samplerate) {
Chris@366: 	return KaiserWindow
Chris@366: 	    (parametersForBandwidth(attenuation, bandwidth, samplerate));
Chris@366:     }
Chris@366: 
Chris@366:     /**
Chris@366:      * Obtain the parameters necessary for a Kaiser window of the
Chris@366:      * given attenuation in dB and transition width in samples.
Chris@366:      */
Chris@366:     static Parameters parametersForTransitionWidth(double attenuation,
Chris@366: 						   double transition);
Chris@366: 
Chris@366:     /**
Chris@366:      * Obtain the parameters necessary for a Kaiser window of the
Chris@366:      * given attenuation in dB and transition bandwidth in Hz for the
Chris@366:      * given samplerate.
Chris@366:      */
Chris@366:     static Parameters parametersForBandwidth(double attenuation,
Chris@366: 					     double bandwidth,
Chris@366: 					     double samplerate) {
Chris@366: 	return parametersForTransitionWidth
Chris@366: 	    (attenuation, (bandwidth * 2 * M_PI) / samplerate);
Chris@366:     } 
Chris@366: 
Chris@366:     int getLength() const {
Chris@366: 	return m_length;
Chris@366:     }
Chris@366: 
Chris@366:     const double *getWindow() const { 
Chris@366: 	return m_window.data();
Chris@366:     }
Chris@366: 
Chris@366:     void cut(double *src) const { 
Chris@366: 	cut(src, src); 
Chris@366:     }
Chris@366: 
Chris@366:     void cut(const double *src, double *dst) const {
Chris@366: 	for (int i = 0; i < m_length; ++i) {
Chris@366: 	    dst[i] = src[i] * m_window[i];
Chris@366: 	}
Chris@366:     }
Chris@366: 
Chris@366: private:
Chris@366:     int m_length;
Chris@366:     double m_beta;
Chris@366:     std::vector<double> m_window;
Chris@366: 
Chris@366:     void init();
Chris@366: };
Chris@366: 
Chris@366: #endif