c@225: /* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */
c@225: 
c@225: /*
c@225:     QM DSP library
c@225:     Centre for Digital Music, Queen Mary, University of London.
c@225:     This file Copyright 2006 Chris Cannam.
c@309: 
c@309:     This program is free software; you can redistribute it and/or
c@309:     modify it under the terms of the GNU General Public License as
c@309:     published by the Free Software Foundation; either version 2 of the
c@309:     License, or (at your option) any later version.  See the file
c@309:     COPYING included with this distribution for more information.
c@225: */
c@225: 
cannam@489: #ifndef QM_DSP_WINDOW_H
cannam@489: #define QM_DSP_WINDOW_H
c@225: 
c@225: #include <cmath>
c@225: #include <iostream>
c@225: #include <map>
c@382: #include <vector>
c@225: 
c@225: enum WindowType {
c@225:     RectangularWindow,
c@225:     BartlettWindow,
c@225:     HammingWindow,
c@225:     HanningWindow,
c@225:     BlackmanWindow,
c@382:     BlackmanHarrisWindow,
c@334: 
c@334:     FirstWindow = RectangularWindow,
c@382:     LastWindow = BlackmanHarrisWindow
c@225: };
c@225: 
c@377: /**
c@377:  * Various shaped windows for sample frame conditioning, including
c@377:  * cosine windows (Hann etc) and triangular and rectangular windows.
c@377:  */
c@225: template <typename T>
c@225: class Window
c@225: {
c@225: public:
c@225:     /**
c@334:      * Construct a windower of the given type and size. 
c@334:      *
c@334:      * Note that the cosine windows are periodic by design, rather
c@334:      * than symmetrical. (A window of size N is equivalent to a
c@334:      * symmetrical window of size N+1 with the final element missing.)
c@225:      */
c@382:     Window(WindowType type, int size) : m_type(type), m_size(size) { encache(); }
c@225:     Window(const Window &w) : m_type(w.m_type), m_size(w.m_size) { encache(); }
c@225:     Window &operator=(const Window &w) {
cannam@483:         if (&w == this) return *this;
cannam@483:         m_type = w.m_type;
cannam@483:         m_size = w.m_size;
cannam@483:         encache();
cannam@483:         return *this;
c@225:     }
c@251:     virtual ~Window() { delete[] m_cache; }
c@225:     
c@225:     void cut(T *src) const { cut(src, src); }
c@280:     void cut(const T *src, T *dst) const {
cannam@494:         for (int i = 0; i < m_size; ++i) {
cannam@494:             dst[i] = src[i] * m_cache[i];
cannam@494:         }
c@225:     }
c@225: 
c@225:     WindowType getType() const { return m_type; }
c@382:     int getSize() const { return m_size; }
c@382: 
c@382:     std::vector<T> getWindowData() const {
c@382:         std::vector<T> d;
c@382:         for (int i = 0; i < m_size; ++i) {
c@382:             d.push_back(m_cache[i]);
c@382:         }
c@382:         return d;
c@382:     }
c@225: 
c@225: protected:
c@225:     WindowType m_type;
c@382:     int m_size;
c@225:     T *m_cache;
c@225:     
c@225:     void encache();
c@225: };
c@225: 
c@225: template <typename T>
c@225: void Window<T>::encache()
c@225: {
c@382:     int n = m_size;
c@225:     T *mult = new T[n];
c@382:     int i;
c@225:     for (i = 0; i < n; ++i) mult[i] = 1.0;
c@225: 
c@225:     switch (m_type) {
cannam@483:                 
c@225:     case RectangularWindow:
c@334:         for (i = 0; i < n; ++i) {
c@334:             mult[i] = mult[i] * 0.5;
cannam@483:         }
cannam@483:         break;
cannam@483:             
c@225:     case BartlettWindow:
c@334:         if (n == 2) {
c@334:             mult[0] = mult[1] = 0; // "matlab compatible"
c@334:         } else if (n == 3) {
c@334:             mult[0] = 0;
c@334:             mult[1] = mult[2] = 2./3.;
c@334:         } else if (n > 3) {
c@334:             for (i = 0; i < n/2; ++i) {
c@334:                 mult[i] = mult[i] * (i / T(n/2));
c@334:                 mult[i + n - n/2] = mult[i + n - n/2] * (1.0 - (i / T(n/2)));
c@334:             }
cannam@483:         }
cannam@483:         break;
cannam@483:             
c@225:     case HammingWindow:
c@334:         if (n > 1) {
c@334:             for (i = 0; i < n; ++i) {
c@334:                 mult[i] = mult[i] * (0.54 - 0.46 * cos(2 * M_PI * i / n));
c@334:             }
cannam@483:         }
cannam@483:         break;
cannam@483:             
c@225:     case HanningWindow:
c@334:         if (n > 1) {
c@334:             for (i = 0; i < n; ++i) {
c@334:                 mult[i] = mult[i] * (0.50 - 0.50 * cos(2 * M_PI * i / n));
c@334:             }
cannam@483:         }
cannam@483:         break;
cannam@483:             
c@225:     case BlackmanWindow:
c@334:         if (n > 1) {
c@334:             for (i = 0; i < n; ++i) {
c@334:                 mult[i] = mult[i] * (0.42 - 0.50 * cos(2 * M_PI * i / n)
c@334:                                      + 0.08 * cos(4 * M_PI * i / n));
c@334:             }
cannam@483:         }
cannam@483:         break;
cannam@483:             
c@382:     case BlackmanHarrisWindow:
c@382:         if (n > 1) {
c@382:             for (i = 0; i < n; ++i) {
c@382:                 mult[i] = mult[i] * (0.35875
c@382:                                      - 0.48829 * cos(2 * M_PI * i / n)
c@382:                                      + 0.14128 * cos(4 * M_PI * i / n)
c@382:                                      - 0.01168 * cos(6 * M_PI * i / n));
c@382:             }
cannam@483:         }
cannam@483:         break;
c@225:     }
cannam@483:            
c@225:     m_cache = mult;
c@225: }
c@225: 
c@225: #endif