comparison src/dsp/KaiserWindow.cpp @ 119:a38d6940f8fb

Bring in dsp dependencies

+/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */
+/*
+    Constant-Q library
+    Copyright (c) 2013-2014 Queen Mary, University of London
+
+    Permission is hereby granted, free of charge, to any person
+    obtaining a copy of this software and associated documentation
+    files (the "Software"), to deal in the Software without
+    restriction, including without limitation the rights to use, copy,
+    modify, merge, publish, distribute, sublicense, and/or sell copies
+    of the Software, and to permit persons to whom the Software is
+    furnished to do so, subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be
+    included in all copies or substantial portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+    EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+    MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+    NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
+    CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
+    CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+    WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+    Except as contained in this notice, the names of the Centre for
+    Digital Music; Queen Mary, University of London; and Chris Cannam
+    shall not be used in advertising or otherwise to promote the sale,
+    use or other dealings in this Software without prior written
+    authorization.
+*/
+
+#include "KaiserWindow.h"
+
+#include "maths/MathUtilities.h"
+
+KaiserWindow::Parameters
+KaiserWindow::parametersForTransitionWidth(double attenuation,
+					   double transition)
+{
+    Parameters p;
+    p.length = 1 + (attenuation > 21.0 ?
+		    ceil((attenuation - 7.95) / (2.285 * transition)) :
+		    ceil(5.79 / transition));
+    p.beta = (attenuation > 50.0 ? 
+	      0.1102 * (attenuation - 8.7) :
+	      attenuation > 21.0 ? 
+	      0.5842 * pow(attenuation - 21.0, 0.4) + 0.07886 * (attenuation - 21.0) :
+	      0);
+    return p;
+}
+
+static double besselTerm(double x, int i)
+{
+    if (i == 0) {
+	return 1;
+    } else {
+	double f = MathUtilities::factorial(i);
+	return pow(x/2, i*2) / (f*f);
+    }
+}
+
+static double bessel0(double x)
+{
+    double b = 0.0;
+    for (int i = 0; i < 20; ++i) {
+	b += besselTerm(x, i);
+    }
+    return b;
+}
+
+void
+KaiserWindow::init()
+{
+    double denominator = bessel0(m_beta);
+    bool even = (m_length % 2 == 0);
+    for (int i = 0; i < (even ? m_length/2 : (m_length+1)/2); ++i) {
+	double k = double(2*i) / double(m_length-1) - 1.0;
+	m_window.push_back(bessel0(m_beta * sqrt(1.0 - k*k)) / denominator);
+    }
+    for (int i = 0; i < (even ? m_length/2 : (m_length-1)/2); ++i) {
+        m_window.push_back(m_window[int(m_length/2) - i - 1]);
+    }
+}