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/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*- vi:set ts=8 sts=4 sw=4: */
/*
Sonic Visualiser
An audio file viewer and annotation editor.
Centre for Digital Music, Queen Mary, University of London.
This file copyright 2006 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 _WINDOW_H_
#define _WINDOW_H_
#include <cmath>
#include <iostream>
#include <string>
#include <map>
#include <cstdlib>
#include "system/System.h"
enum WindowType {
RectangularWindow,
BartlettWindow,
HammingWindow,
HanningWindow,
BlackmanWindow,
GaussianWindow,
ParzenWindow,
NuttallWindow,
BlackmanHarrisWindow
};
template <typename T>
class Window
{
public:
/**
* Construct a windower of the given type and size.
*
* Note that the cosine windows are periodic by design, rather
* than symmetrical. (A window of size N is equivalent to a
* symmetrical window of size N+1 with the final element missing.)
*/
Window(WindowType type, int 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 (int i = 0; i < m_size; ++i) dst[i] = src[i] * m_cache[i];
}
T getArea() { return m_area; }
T getValue(int i) { return m_cache[i]; }
WindowType getType() const { return m_type; }
int getSize() const { return m_size; }
// The names used by these functions are un-translated, for use in
// e.g. XML I/O. Use Preferences::getPropertyValueLabel if you
// want translated names for use in the user interface.
static std::string getNameForType(WindowType type);
static WindowType getTypeForName(std::string name);
protected:
WindowType m_type;
int m_size;
T *m_cache;
T m_area;
void encache();
void cosinewin(T *, double, double, double, double);
};
template <typename T>
void Window<T>::encache()
{
const int n = 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] *= T(0.5);
}
break;
case BartlettWindow:
for (i = 0; i < n/2; ++i) {
mult[i] *= T(i) / T(n/2);
mult[i + n/2] *= T(1.0) - T(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] *= T(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 = T(2 * pow(1.0 - (T(N)/2 - T(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 = T(1.0 - 6 * pow(T(wn) / (T(N)/2), 2) * (1.0 - T(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 /= T(n);
}
template <typename T>
void Window<T>::cosinewin(T *mult, double a0, double a1, double a2, double a3)
{
const int n = m_size;
for (int i = 0; i < n; ++i) {
mult[i] *= T(a0
- a1 * cos((2 * M_PI * i) / n)
+ a2 * cos((4 * M_PI * i) / n)
- a3 * cos((6 * M_PI * i) / n));
}
}
template <typename T>
std::string
Window<T>::getNameForType(WindowType type)
{
switch (type) {
case RectangularWindow: return "rectangular";
case BartlettWindow: return "bartlett";
case HammingWindow: return "hamming";
case HanningWindow: return "hanning";
case BlackmanWindow: return "blackman";
case GaussianWindow: return "gaussian";
case ParzenWindow: return "parzen";
case NuttallWindow: return "nuttall";
case BlackmanHarrisWindow: return "blackman-harris";
}
std::cerr << "WARNING: Window::getNameForType: unknown type "
<< type << std::endl;
return "unknown";
}
template <typename T>
WindowType
Window<T>::getTypeForName(std::string name)
{
if (name == "rectangular") return RectangularWindow;
if (name == "bartlett") return BartlettWindow;
if (name == "hamming") return HammingWindow;
if (name == "hanning") return HanningWindow;
if (name == "blackman") return BlackmanWindow;
if (name == "gaussian") return GaussianWindow;
if (name == "parzen") return ParzenWindow;
if (name == "nuttall") return NuttallWindow;
if (name == "blackman-harris") return BlackmanHarrisWindow;
std::cerr << "WARNING: Window::getTypeForName: unknown name \""
<< name << "\", defaulting to \"hanning\"" << std::endl;
return HanningWindow;
}
#endif
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