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Diffstat (limited to 'src/loris/KaiserWindow.h')
| -rw-r--r-- | src/loris/KaiserWindow.h | 112 |
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diff --git a/src/loris/KaiserWindow.h b/src/loris/KaiserWindow.h new file mode 100644 index 0000000..d0ba494 --- /dev/null +++ b/src/loris/KaiserWindow.h @@ -0,0 +1,112 @@ +#ifndef INCLUDE_KAISERWINDOW_H +#define INCLUDE_KAISERWINDOW_H +/* + * This is the Loris C++ Class Library, implementing analysis, + * manipulation, and synthesis of digitized sounds using the Reassigned + * Bandwidth-Enhanced Additive Sound Model. + * + * Loris is Copyright (c) 1999-2010 by Kelly Fitz and Lippold Haken + * + * 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. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY, without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + * + * + * KaiserWindow.h + * + * Definition of class Loris::KaiserWindow. + * + * Kelly Fitz, 14 Dec 1999 + * loris@cerlsoundgroup.org + * + * http://www.cerlsoundgroup.org/Loris/ + * + */ + +#include <vector> + +// begin namespace +namespace Loris { + +// --------------------------------------------------------------------------- +// class KaiserWindow +// +//! Computes samples of a Kaiser window +//! function (see Kaiser and Schafer, 1980) for windowing FFT data. +// +class KaiserWindow +{ +// -- public interface -- +public: + + // -- window building -- + + //! Build a new Kaiser analysis window having the specified shaping + //! parameter. See Oppenheim and Schafer: "Digital Signal Processing" + //! (1975), p. 452 for further explanation of the Kaiser window. Also, + //! see Kaiser and Schafer, 1980. + //! + //! \param win is the vector that will store the window + //! samples. The number of samples computed will be + //! equal to the length of this vector. Any previous + //! contents will be overwritten. + //! \param shape is the Kaiser shaping parameter, controlling + //! the sidelobe rejection level. + static void buildWindow( std::vector< double > & win, double shape ); + + //! Build a new time-derivative Kaiser analysis window having the + //! specified shaping parameter, for computing frequency reassignment. + //! The closed form for the time derivative can be obtained from the + //! property of modified Bessel functions that the derivative of the + //! zeroeth order function is equal to the first order function. + //! + //! \param win is the vector that will store the window + //! samples. The number of samples computed will be + //! equal to the length of this vector. Any previous + //! contents will be overwritten. + //! \param shape is the Kaiser shaping parameter, controlling + //! the sidelobe rejection level. + static void buildTimeDerivativeWindow( std::vector< double > & win, double shape ); + + + // -- window parameter estimation -- + + //! Compute a shaping parameter that will achieve the specified + //! level of sidelobe rejection. + //! + //! \param atten is the desired sidelobe attenuation in + //! positive decibels (e.g. 65 dB) + //! \returns the Kaiser shaping paramater + static double computeShape( double atten ); + + //! Compute the necessary length in samples of a Kaiser window + //! having the specified shaping parameter that has the + //! desired main lobe width. + //! + //! \param width is the desired main lobe width expressed + //! as a fraction of the sample rate. + //! \param alpha is the Kaiser shaping parameter (the + //! main lobe width is influenced primarily by the + //! window length,but also by the shape). + //! \returns the window length in samples + static unsigned long computeLength( double width, double alpha ); + +// construction is not allowed: +private: + KaiserWindow( void ); + +}; // end of class KaiserWindow + +} // end of namespace Loris + +#endif /* ndef INCLUDE_KAISERWINDOW_H */ |