Chris@0: /* -*- c-basic-offset: 4 -*-  vi:set ts=8 sts=4 sw=4: */
Chris@0: 
Chris@0: /*
Chris@0:     A waveform viewer and audio annotation editor.
Chris@2:     Chris Cannam, Queen Mary University of London, 2005-2006
Chris@0:     
Chris@0:     This is experimental software.  Not for distribution.
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@0:     ParzenWindow
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@0: 	if (&w == this) return;
Chris@0: 	m_type = w.m_type;
Chris@0: 	m_size = w.m_size;
Chris@0: 	encache();
Chris@0: 	return *this;
Chris@0:     }
Chris@0:     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@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@0:     
Chris@0:     void encache();
Chris@0: };
Chris@0: 
Chris@0: template <typename T>
Chris@0: void Window<T>::encache()
Chris@0: {
Chris@0:     size_t n = m_size;
Chris@0:     T *mult = new T[n];
Chris@0:     size_t 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@0: 	    mult[i] = 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@0: 	    mult[i] = mult[i] * (i / T(n/2));
Chris@0: 	    mult[i + n/2] = mult[i + n/2] * (1.0 - (i / T(n/2)));
Chris@0: 	}
Chris@0: 	break;
Chris@0: 	    
Chris@0:     case HammingWindow:
Chris@0: 	for (i = 0; i < n; ++i) {
Chris@0: 	    mult[i] = mult[i] * (0.54 - 0.46 * cos(2 * M_PI * i / n));
Chris@0: 	}
Chris@0: 	break;
Chris@0: 	    
Chris@0:     case HanningWindow:
Chris@0: 	for (i = 0; i < n; ++i) {
Chris@0: 	    mult[i] = mult[i] * (0.50 - 0.50 * cos(2 * M_PI * i / n));
Chris@0: 	}
Chris@0: 	break;
Chris@0: 	    
Chris@0:     case BlackmanWindow:
Chris@0: 	for (i = 0; i < n; ++i) {
Chris@0: 	    mult[i] = mult[i] * (0.42 - 0.50 * cos(2 * M_PI * i / n)
Chris@0: 				 + 0.08 * cos(4 * M_PI * i / n));
Chris@0: 	}
Chris@0: 	break;
Chris@0: 	    
Chris@0:     case GaussianWindow:
Chris@0: 	for (i = 0; i < n; ++i) {
Chris@0: 	    mult[i] = mult[i] * exp((-1.0 / (n*n)) * ((T(2*i) - n) *
Chris@0: 						      (T(2*i) - n)));
Chris@0: 	}
Chris@0: 	break;
Chris@0: 	    
Chris@0:     case ParzenWindow:
Chris@0: 	for (i = 0; i < n; ++i) {
Chris@0: 	    mult[i] = mult[i] * (1.0 - fabs((T(2*i) - n) / T(n + 1)));
Chris@0: 	}
Chris@0: 	break;
Chris@0:     }
Chris@0: 	
Chris@0:     m_cache = mult;
Chris@0: }
Chris@0: 
Chris@0: #endif