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/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*- vi:set ts=8 sts=4 sw=4: */
/*
Rubber Band
An audio time-stretching and pitch-shifting library.
Copyright 2007 Chris Cannam.
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 _RUBBERBAND_WINDOW_H_
#define _RUBBERBAND_WINDOW_H_
#include <cmath>
#include <iostream>
#include <map>
namespace RubberBand {
enum WindowType {
RectangularWindow,
BartlettWindow,
HammingWindow,
HanningWindow,
BlackmanWindow,
GaussianWindow,
ParzenWindow,
NuttallWindow,
BlackmanHarrisWindow
};
template <typename T>
class Window
{
public:
/**
* Construct a windower of the given type.
*/
Window(WindowType type, size_t size) : m_type(type), m_size(size) { encache(); }
Window(const Window &w) : m_type(w.m_type), m_size(w.m_size) { encache(); }
Window &operator=(const Window &w) {
if (&w == this) return *this;
m_type = w.m_type;
m_size = w.m_size;
encache();
return *this;
}
virtual ~Window() { delete[] m_cache; }
void cut(T *src) const { cut(src, src); }
void cut(T *src, T *dst) const {
for (size_t i = 0; i < m_size; ++i) dst[i] = src[i] * m_cache[i];
}
T getArea() { return m_area; }
T getValue(size_t i) { return m_cache[i]; }
WindowType getType() const { return m_type; }
size_t getSize() const { return m_size; }
protected:
WindowType m_type;
size_t m_size;
T *m_cache;
T m_area;
void encache();
void cosinewin(T *, T, T, T, T);
};
template <typename T>
void Window<T>::encache()
{
int n = int(m_size);
T *mult = new T[n];
int i;
for (i = 0; i < n; ++i) mult[i] = 1.0;
switch (m_type) {
case RectangularWindow:
for (i = 0; i < n; ++i) {
mult[i] *= 0.5;
}
break;
case BartlettWindow:
for (i = 0; i < n/2; ++i) {
mult[i] *= (i / T(n/2));
mult[i + n/2] *= (1.0 - (i / T(n/2)));
}
break;
case HammingWindow:
cosinewin(mult, 0.54, 0.46, 0.0, 0.0);
break;
case HanningWindow:
cosinewin(mult, 0.50, 0.50, 0.0, 0.0);
break;
case BlackmanWindow:
cosinewin(mult, 0.42, 0.50, 0.08, 0.0);
break;
case GaussianWindow:
for (i = 0; i < n; ++i) {
mult[i] *= pow(2, - pow((i - (n-1)/2.0) / ((n-1)/2.0 / 3), 2));
}
break;
case ParzenWindow:
{
int N = n-1;
for (i = 0; i < N/4; ++i) {
T m = 2 * pow(1.0 - (T(N)/2 - i) / (T(N)/2), 3);
mult[i] *= m;
mult[N-i] *= m;
}
for (i = N/4; i <= N/2; ++i) {
int wn = i - N/2;
T m = 1.0 - 6 * pow(wn / (T(N)/2), 2) * (1.0 - abs(wn) / (T(N)/2));
mult[i] *= m;
mult[N-i] *= m;
}
break;
}
case NuttallWindow:
cosinewin(mult, 0.3635819, 0.4891775, 0.1365995, 0.0106411);
break;
case BlackmanHarrisWindow:
cosinewin(mult, 0.35875, 0.48829, 0.14128, 0.01168);
break;
}
m_cache = mult;
m_area = 0;
for (int i = 0; i < n; ++i) {
m_area += m_cache[i];
}
m_area /= n;
}
template <typename T>
void Window<T>::cosinewin(T *mult, T a0, T a1, T a2, T a3)
{
int n = int(m_size);
for (int i = 0; i < n; ++i) {
mult[i] *= (a0
- a1 * cos(2 * M_PI * i / n)
+ a2 * cos(4 * M_PI * i / n)
- a3 * cos(6 * M_PI * i / n));
}
}
}
#endif
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