156 lines
3.9 KiB
C++
156 lines
3.9 KiB
C++
/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*- vi:set ts=8 sts=4 sw=4: */
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/*
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QM DSP library
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Centre for Digital Music, Queen Mary, University of London.
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This file Copyright 2006 Chris Cannam.
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License as
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published by the Free Software Foundation; either version 2 of the
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License, or (at your option) any later version. See the file
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COPYING included with this distribution for more information.
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*/
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#ifndef _WINDOW_H_
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#define _WINDOW_H_
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#include <cmath>
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#include <iostream>
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#include <map>
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#include <vector>
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enum WindowType {
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RectangularWindow,
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BartlettWindow,
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HammingWindow,
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HanningWindow,
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BlackmanWindow,
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BlackmanHarrisWindow,
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FirstWindow = RectangularWindow,
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LastWindow = BlackmanHarrisWindow
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};
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/**
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* Various shaped windows for sample frame conditioning, including
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* cosine windows (Hann etc) and triangular and rectangular windows.
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*/
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template <typename T>
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class Window
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{
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public:
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/**
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* Construct a windower of the given type and size.
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*
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* Note that the cosine windows are periodic by design, rather
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* than symmetrical. (A window of size N is equivalent to a
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* symmetrical window of size N+1 with the final element missing.)
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*/
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Window(WindowType type, int size) : m_type(type), m_size(size) { encache(); }
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Window(const Window &w) : m_type(w.m_type), m_size(w.m_size) { encache(); }
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Window &operator=(const Window &w) {
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if (&w == this) return *this;
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m_type = w.m_type;
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m_size = w.m_size;
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encache();
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return *this;
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}
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virtual ~Window() { delete[] m_cache; }
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void cut(T *src) const { cut(src, src); }
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void cut(const T *src, T *dst) const {
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for (int i = 0; i < m_size; ++i) dst[i] = src[i] * m_cache[i];
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}
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WindowType getType() const { return m_type; }
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int getSize() const { return m_size; }
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std::vector<T> getWindowData() const {
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std::vector<T> d;
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for (int i = 0; i < m_size; ++i) {
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d.push_back(m_cache[i]);
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}
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return d;
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}
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protected:
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WindowType m_type;
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int m_size;
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T *m_cache;
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void encache();
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};
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template <typename T>
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void Window<T>::encache()
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{
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int n = m_size;
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T *mult = new T[n];
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int i;
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for (i = 0; i < n; ++i) mult[i] = 1.0;
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switch (m_type) {
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case RectangularWindow:
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for (i = 0; i < n; ++i) {
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mult[i] = mult[i] * 0.5;
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}
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break;
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case BartlettWindow:
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if (n == 2) {
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mult[0] = mult[1] = 0; // "matlab compatible"
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} else if (n == 3) {
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mult[0] = 0;
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mult[1] = mult[2] = 2./3.;
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} else if (n > 3) {
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for (i = 0; i < n/2; ++i) {
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mult[i] = mult[i] * (i / T(n/2));
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mult[i + n - n/2] = mult[i + n - n/2] * (1.0 - (i / T(n/2)));
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}
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}
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break;
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case HammingWindow:
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if (n > 1) {
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for (i = 0; i < n; ++i) {
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mult[i] = mult[i] * (0.54 - 0.46 * cos(2 * M_PI * i / n));
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}
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}
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break;
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case HanningWindow:
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if (n > 1) {
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for (i = 0; i < n; ++i) {
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mult[i] = mult[i] * (0.50 - 0.50 * cos(2 * M_PI * i / n));
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}
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}
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break;
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case BlackmanWindow:
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if (n > 1) {
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for (i = 0; i < n; ++i) {
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mult[i] = mult[i] * (0.42 - 0.50 * cos(2 * M_PI * i / n)
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+ 0.08 * cos(4 * M_PI * i / n));
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}
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}
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break;
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case BlackmanHarrisWindow:
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if (n > 1) {
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for (i = 0; i < n; ++i) {
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mult[i] = mult[i] * (0.35875
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- 0.48829 * cos(2 * M_PI * i / n)
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+ 0.14128 * cos(4 * M_PI * i / n)
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- 0.01168 * cos(6 * M_PI * i / n));
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}
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}
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break;
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}
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m_cache = mult;
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}
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#endif
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