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view base/Window.h @ 325:82a2d3161e14
* Document FileSource
author | Chris Cannam |
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date | Thu, 01 Nov 2007 12:34:17 +0000 (2007-11-01) |
parents | 524bcd89743b |
children | d7c41483af8f |
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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 <map> 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