comparison base/KaiserWindow.h @ 349:b247af4c23d2

Add Kaiser window (and some tests for it)

+/* -*- 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>
+
+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.data();
+    }
+
+    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