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/***************************************************************************
WindowFunction.cpp - Windows functions for signal processing
-------------------
begin : Feb 05 2001
copyright : (C) 2001 by Thomas Eschenbacher
email : Thomas Eschenbacher <thomas.eschenbacher@gmx.de>
***************************************************************************/
/***************************************************************************
* *
* 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. *
* *
***************************************************************************/
#include "config.h"
#include <KLocalizedString>
#include <math.h>
#include "libkwave/String.h"
#include "libkwave/Utils.h"
#include "libkwave/WindowFunction.h"
//***************************************************************************
//***************************************************************************
void Kwave::WindowFunction::InitializedTypesMap::fill()
{
append(WINDOW_FUNC_NONE, WINDOW_FUNC_NONE,
_("none"), kli18n("None"));
append(WINDOW_FUNC_HAMMING, WINDOW_FUNC_HAMMING,
_("hamming"), kli18n("Hamming"));
append(WINDOW_FUNC_HANNING, WINDOW_FUNC_HANNING,
_("hanning"), kli18n("Hanning"));
append(WINDOW_FUNC_BLACKMAN, WINDOW_FUNC_BLACKMAN,
_("blackman"), kli18n("Blackman"));
append(WINDOW_FUNC_TRIANGULAR, WINDOW_FUNC_TRIANGULAR,
_("triangular"), kli18n("Triangular"));
}
//***************************************************************************
// static initializer
Kwave::WindowFunction::InitializedTypesMap Kwave::WindowFunction::m_types_map;
//***************************************************************************
//***************************************************************************
Kwave::WindowFunction::WindowFunction(Kwave::window_function_t type)
:m_type(type)
{
}
//***************************************************************************
Kwave::WindowFunction::~WindowFunction()
{
}
//***************************************************************************
QVector<double> Kwave::WindowFunction::points(unsigned int len) const
{
QVector<double> out(len);
Q_ASSERT(out.count() == Kwave::toInt(len));
if (out.count() != Kwave::toInt(len)) {
out.resize(0);
return out;
}
// Hanning, Hamming, Blackman window functions as proposed
// in Oppenheim, Schafer, p.241 ff
switch (m_type) {
case WINDOW_FUNC_NONE: //rectangular window
for (unsigned int i = 0; i < len; i++)
out[i] = 1;
break;
case WINDOW_FUNC_HANNING:
for (unsigned int i = 0; i < len; i++)
out[i] = 0.5 * (1 - cos(i * 2 * M_PI / (len - 1)));
break;
case WINDOW_FUNC_HAMMING:
for (unsigned int i = 0; i < len; i++)
out[i] = 0.54-(0.46 * cos(static_cast<double>(i) * 2 * M_PI /
(len - 1)));
break;
case WINDOW_FUNC_BLACKMAN:
for (unsigned int i = 0; i < len; i++)
out[i] = 0.42-(0.50 * cos(static_cast<double>(i) * 2 * M_PI /
(len - 1))) +
(0.08 * cos(static_cast<double>(i) * 4 * M_PI /
(len - 1)));
break;
case WINDOW_FUNC_TRIANGULAR:
for (unsigned int i = 0; i < len / 2; i++)
out[i] = static_cast<double>(i) / (len / 2 - 1);
for (unsigned int i = len / 2; i < len; i++)
out[i] = 1 - (static_cast<double>(i) - len / 2) / (len / 2 - 1);
break;
DEFAULT_IMPOSSIBLE;
}
return out;
}
//***************************************************************************
//***************************************************************************
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