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#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 */
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