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Diffstat (limited to 'libs/qm-dsp/base/KaiserWindow.h')
-rw-r--r-- | libs/qm-dsp/base/KaiserWindow.h | 105 |
1 files changed, 105 insertions, 0 deletions
diff --git a/libs/qm-dsp/base/KaiserWindow.h b/libs/qm-dsp/base/KaiserWindow.h new file mode 100644 index 0000000000..f16a4b6c16 --- /dev/null +++ b/libs/qm-dsp/base/KaiserWindow.h @@ -0,0 +1,105 @@ +/* -*- 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> + +/** + * Kaiser window: A windower whose bandwidth and sidelobe height + * (signal-noise ratio) can be specified. These parameters are traded + * off against the window length. + */ +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 |