Chris@49: /* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */
Chris@0: 
Chris@0: /*
Chris@52:     Sonic Visualiser
Chris@52:     An audio file viewer and annotation editor.
Chris@52:     Centre for Digital Music, Queen Mary, University of London.
Chris@52:     This file copyright 2006 Chris Cannam.
Chris@0:     
Chris@52:     This program is free software; you can redistribute it and/or
Chris@52:     modify it under the terms of the GNU General Public License as
Chris@52:     published by the Free Software Foundation; either version 2 of the
Chris@52:     License, or (at your option) any later version.  See the file
Chris@52:     COPYING included with this distribution for more information.
Chris@0: */
Chris@0: 
Chris@0: #ifndef _WINDOW_H_
Chris@0: #define _WINDOW_H_
Chris@0: 
Chris@0: #include <cmath>
Chris@0: #include <iostream>
Chris@0: #include <map>
Chris@0: 
Chris@0: enum WindowType {
Chris@0:     RectangularWindow,
Chris@0:     BartlettWindow,
Chris@0:     HammingWindow,
Chris@0:     HanningWindow,
Chris@0:     BlackmanWindow,
Chris@0:     GaussianWindow,
Chris@142:     ParzenWindow,
Chris@142:     NuttallWindow,
Chris@142:     BlackmanHarrisWindow
Chris@0: };
Chris@0: 
Chris@0: template <typename T>
Chris@0: class Window
Chris@0: {
Chris@0: public:
Chris@0:     /**
Chris@0:      * Construct a windower of the given type.
Chris@0:      */
Chris@0:     Window(WindowType type, size_t size) : m_type(type), m_size(size) { encache(); }
Chris@0:     Window(const Window &w) : m_type(w.m_type), m_size(w.m_size) { encache(); }
Chris@0:     Window &operator=(const Window &w) {
Chris@52: 	if (&w == this) return *this;
Chris@0: 	m_type = w.m_type;
Chris@0: 	m_size = w.m_size;
Chris@0: 	encache();
Chris@0: 	return *this;
Chris@0:     }
Chris@142:     virtual ~Window() { delete[] m_cache; }
Chris@0:     
Chris@0:     void cut(T *src) const { cut(src, src); }
Chris@0:     void cut(T *src, T *dst) const {
Chris@0: 	for (size_t i = 0; i < m_size; ++i) dst[i] = src[i] * m_cache[i];
Chris@0:     }
Chris@0: 
Chris@162:     T getArea() { return m_area; }
Chris@140:     T getValue(size_t i) { return m_cache[i]; }
Chris@140: 
Chris@0:     WindowType getType() const { return m_type; }
Chris@0:     size_t getSize() const { return m_size; }
Chris@0: 
Chris@0: protected:
Chris@0:     WindowType m_type;
Chris@0:     size_t m_size;
Chris@0:     T *m_cache;
Chris@162:     T m_area;
Chris@0:     
Chris@0:     void encache();
Chris@142:     void cosinewin(T *, T, T, T, T);
Chris@0: };
Chris@0: 
Chris@0: template <typename T>
Chris@0: void Window<T>::encache()
Chris@0: {
Chris@141:     int n = int(m_size);
Chris@0:     T *mult = new T[n];
Chris@141:     int i;
Chris@0:     for (i = 0; i < n; ++i) mult[i] = 1.0;
Chris@0: 
Chris@0:     switch (m_type) {
Chris@0: 		
Chris@0:     case RectangularWindow:
Chris@0: 	for (i = 0; i < n; ++i) {
Chris@141: 	    mult[i] *= 0.5;
Chris@0: 	}
Chris@0: 	break;
Chris@0: 	    
Chris@0:     case BartlettWindow:
Chris@0: 	for (i = 0; i < n/2; ++i) {
Chris@141: 	    mult[i] *= (i / T(n/2));
Chris@141: 	    mult[i + n/2] *= (1.0 - (i / T(n/2)));
Chris@0: 	}
Chris@0: 	break;
Chris@0: 	    
Chris@0:     case HammingWindow:
Chris@142:         cosinewin(mult, 0.54, 0.46, 0.0, 0.0);
Chris@0: 	break;
Chris@0: 	    
Chris@0:     case HanningWindow:
Chris@142:         cosinewin(mult, 0.50, 0.50, 0.0, 0.0);
Chris@0: 	break;
Chris@0: 	    
Chris@0:     case BlackmanWindow:
Chris@142:         cosinewin(mult, 0.42, 0.50, 0.08, 0.0);
Chris@0: 	break;
Chris@0: 	    
Chris@0:     case GaussianWindow:
Chris@0: 	for (i = 0; i < n; ++i) {
Chris@142:             mult[i] *= pow(2, - pow((i - (n-1)/2.0) / ((n-1)/2.0 / 3), 2));
Chris@0: 	}
Chris@0: 	break;
Chris@0: 	    
Chris@0:     case ParzenWindow:
Chris@141:     {
Chris@141:         int N = n-1;
Chris@141:         for (i = 0; i < N/4; ++i) {
Chris@141:             T m = 2 * pow(1.0 - (T(N)/2 - i) / (T(N)/2), 3);
Chris@141:             mult[i] *= m;
Chris@141:             mult[N-i] *= m;
Chris@141:         }
Chris@141:         for (i = N/4; i <= N/2; ++i) {
Chris@141:             int wn = i - N/2;
Chris@141:             T m = 1.0 - 6 * pow(wn / (T(N)/2), 2) * (1.0 - abs(wn) / (T(N)/2));
Chris@141:             mult[i] *= m;
Chris@141:             mult[N-i] *= m;
Chris@141:         }            
Chris@142:         break;
Chris@142:     }
Chris@142: 
Chris@142:     case NuttallWindow:
Chris@142:         cosinewin(mult, 0.3635819, 0.4891775, 0.1365995, 0.0106411);
Chris@0: 	break;
Chris@142: 
Chris@142:     case BlackmanHarrisWindow:
Chris@142:         cosinewin(mult, 0.35875, 0.48829, 0.14128, 0.01168);
Chris@142:         break;
Chris@0:     }
Chris@0: 	
Chris@0:     m_cache = mult;
Chris@162: 
Chris@162:     m_area = 0;
Chris@162:     for (int i = 0; i < n; ++i) {
Chris@162:         m_area += m_cache[i];
Chris@162:     }
Chris@162:     m_area /= n;
Chris@0: }
Chris@0: 
Chris@142: template <typename T>
Chris@142: void Window<T>::cosinewin(T *mult, T a0, T a1, T a2, T a3)
Chris@142: {
Chris@142:     int n = int(m_size);
Chris@142:     for (int i = 0; i < n; ++i) {
Chris@142:         mult[i] *= (a0
Chris@142:                     - a1 * cos(2 * M_PI * i / n)
Chris@142:                     + a2 * cos(4 * M_PI * i / n)
Chris@142:                     - a3 * cos(6 * M_PI * i / n));
Chris@142:     }
Chris@142: }
Chris@142: 
Chris@0: #endif