comparison base/Window.h @ 0:da6937383da8

initial import

+/* -*- c-basic-offset: 4 -*-  vi:set ts=8 sts=4 sw=4: */
+
+/*
+    A waveform viewer and audio annotation editor.
+    Chris Cannam, Queen Mary University of London, 2005
+    
+    This is experimental software.  Not for distribution.
+*/
+
+#ifndef _WINDOW_H_
+#define _WINDOW_H_
+
+#include <cmath>
+#include <iostream>
+#include <map>
+
+enum WindowType {
+    RectangularWindow,
+    BartlettWindow,
+    HammingWindow,
+    HanningWindow,
+    BlackmanWindow,
+    GaussianWindow,
+    ParzenWindow
+};
+
+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;
+	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];
+    }
+
+    WindowType getType() const { return m_type; }
+    size_t getSize() const { return m_size; }
+
+protected:
+    WindowType m_type;
+    size_t m_size;
+    T *m_cache;
+    
+    void encache();
+};
+
+template <typename T>
+void Window<T>::encache()
+{
+    size_t n = m_size;
+    T *mult = new T[n];
+    size_t i;
+    for (i = 0; i < n; ++i) mult[i] = 1.0;
+
+    switch (m_type) {
+		
+    case RectangularWindow:
+	for (i = 0; i < n; ++i) {
+	    mult[i] = mult[i] * 0.5;
+	}
+	break;
+	    
+    case BartlettWindow:
+	for (i = 0; i < n/2; ++i) {
+	    mult[i] = mult[i] * (i / T(n/2));
+	    mult[i + n/2] = mult[i + n/2] * (1.0 - (i / T(n/2)));
+	}
+	break;
+	    
+    case HammingWindow:
+	for (i = 0; i < n; ++i) {
+	    mult[i] = mult[i] * (0.54 - 0.46 * cos(2 * M_PI * i / n));
+	}
+	break;
+	    
+    case HanningWindow:
+	for (i = 0; i < n; ++i) {
+	    mult[i] = mult[i] * (0.50 - 0.50 * cos(2 * M_PI * i / n));
+	}
+	break;
+	    
+    case BlackmanWindow:
+	for (i = 0; i < n; ++i) {
+	    mult[i] = mult[i] * (0.42 - 0.50 * cos(2 * M_PI * i / n)
+				 + 0.08 * cos(4 * M_PI * i / n));
+	}
+	break;
+	    
+    case GaussianWindow:
+	for (i = 0; i < n; ++i) {
+	    mult[i] = mult[i] * exp((-1.0 / (n*n)) * ((T(2*i) - n) *
+						      (T(2*i) - n)));
+	}
+	break;
+	    
+    case ParzenWindow:
+	for (i = 0; i < n; ++i) {
+	    mult[i] = mult[i] * (1.0 - fabs((T(2*i) - n) / T(n + 1)));
+	}
+	break;
+    }
+	
+    m_cache = mult;
+}
+
+#endif