Chris@317: /* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */
Chris@317: 
Chris@317: /*
Chris@317:     Vamp
Chris@317: 
Chris@317:     An API for audio analysis and feature extraction plugins.
Chris@317: 
Chris@317:     Centre for Digital Music, Queen Mary, University of London.
Chris@317:     Copyright 2006-2011 Chris Cannam and QMUL.
Chris@317: 
Chris@317:     Permission is hereby granted, free of charge, to any person
Chris@317:     obtaining a copy of this software and associated documentation
Chris@317:     files (the "Software"), to deal in the Software without
Chris@317:     restriction, including without limitation the rights to use, copy,
Chris@317:     modify, merge, publish, distribute, sublicense, and/or sell copies
Chris@317:     of the Software, and to permit persons to whom the Software is
Chris@317:     furnished to do so, subject to the following conditions:
Chris@317: 
Chris@317:     The above copyright notice and this permission notice shall be
Chris@317:     included in all copies or substantial portions of the Software.
Chris@317: 
Chris@317:     THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
Chris@317:     EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
Chris@317:     MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
Chris@317:     NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR
Chris@317:     ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
Chris@317:     CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
Chris@317:     WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
Chris@317: 
Chris@317:     Except as contained in this notice, the names of the Centre for
Chris@317:     Digital Music; Queen Mary, University of London; and Chris Cannam
Chris@317:     shall not be used in advertising or otherwise to promote the sale,
Chris@317:     use or other dealings in this Software without prior written
Chris@317:     authorization.
Chris@317: */
Chris@317: 
Chris@317: #ifndef _WINDOW_H_
Chris@317: #define _WINDOW_H_
Chris@317: 
Chris@317: #include <vamp-hostsdk/hostguard.h>
Chris@317: 
Chris@317: #include <cmath>
Chris@317: #include <cstdlib>
Chris@317: 
Chris@317: _VAMP_SDK_HOSTSPACE_BEGIN(Window.h)
Chris@317: 
Chris@317: template <typename T>
Chris@317: class Window
Chris@317: {
Chris@317: public:
Chris@317:     enum WindowType {
Chris@317:         RectangularWindow,
Chris@317:         BartlettWindow,
Chris@317:         HammingWindow,
Chris@317:         HanningWindow,
Chris@317:         BlackmanWindow,
Chris@317:         NuttallWindow,
Chris@317:         BlackmanHarrisWindow
Chris@317:     };
Chris@317: 
Chris@317:     /**
Chris@317:      * Construct a windower of the given type.
Chris@317:      */
Chris@317:     Window(WindowType type, size_t size) : m_type(type), m_size(size) { encache(); }
Chris@317:     Window(const Window &w) : m_type(w.m_type), m_size(w.m_size) { encache(); }
Chris@317:     Window &operator=(const Window &w) {
Chris@317: 	if (&w == this) return *this;
Chris@317: 	m_type = w.m_type;
Chris@317: 	m_size = w.m_size;
Chris@317: 	encache();
Chris@317: 	return *this;
Chris@317:     }
Chris@317:     virtual ~Window() { delete[] m_cache; }
Chris@317:     
Chris@317:     void cut(T *src) const { cut(src, src); }
Chris@317:     void cut(T *src, T *dst) const {
Chris@317: 	for (size_t i = 0; i < m_size; ++i) dst[i] = src[i] * m_cache[i];
Chris@317:     }
Chris@317:     template <typename T0>
Chris@317:     void cut(T0 *src, T *dst) const {
Chris@317: 	for (size_t i = 0; i < m_size; ++i) dst[i] = src[i] * m_cache[i];
Chris@317:     }
Chris@317: 
Chris@317:     T getArea() { return m_area; }
Chris@317:     T getValue(size_t i) { return m_cache[i]; }
Chris@317: 
Chris@317:     WindowType getType() const { return m_type; }
Chris@317:     size_t getSize() const { return m_size; }
Chris@317: 
Chris@317: protected:
Chris@317:     WindowType m_type;
Chris@317:     size_t m_size;
Chris@317:     T *m_cache;
Chris@317:     T m_area;
Chris@317:     
Chris@317:     void encache();
Chris@317:     void cosinewin(T *, T, T, T, T);
Chris@317: };
Chris@317: 
Chris@317: template <typename T>
Chris@317: void Window<T>::encache()
Chris@317: {
Chris@317:     int n = int(m_size);
Chris@317:     T *mult = new T[n];
Chris@317:     int i;
Chris@317:     for (i = 0; i < n; ++i) mult[i] = 1.0;
Chris@317: 
Chris@317:     switch (m_type) {
Chris@317: 		
Chris@317:     case RectangularWindow:
Chris@317: 	for (i = 0; i < n; ++i) {
Chris@317: 	    mult[i] *= 0.5;
Chris@317: 	}
Chris@317: 	break;
Chris@317: 	    
Chris@317:     case BartlettWindow:
Chris@317: 	for (i = 0; i < n/2; ++i) {
Chris@317: 	    mult[i] *= (i / T(n/2));
Chris@317: 	    mult[i + n/2] *= (1.0 - (i / T(n/2)));
Chris@317: 	}
Chris@317: 	break;
Chris@317: 	    
Chris@317:     case HammingWindow:
Chris@317:         cosinewin(mult, 0.54, 0.46, 0.0, 0.0);
Chris@317: 	break;
Chris@317: 	    
Chris@317:     case HanningWindow:
Chris@317:         cosinewin(mult, 0.50, 0.50, 0.0, 0.0);
Chris@317: 	break;
Chris@317: 	    
Chris@317:     case BlackmanWindow:
Chris@317:         cosinewin(mult, 0.42, 0.50, 0.08, 0.0);
Chris@317: 	break;
Chris@317: 
Chris@317:     case NuttallWindow:
Chris@317:         cosinewin(mult, 0.3635819, 0.4891775, 0.1365995, 0.0106411);
Chris@317: 	break;
Chris@317: 
Chris@317:     case BlackmanHarrisWindow:
Chris@317:         cosinewin(mult, 0.35875, 0.48829, 0.14128, 0.01168);
Chris@317:         break;
Chris@317:     }
Chris@317: 	
Chris@317:     m_cache = mult;
Chris@317: 
Chris@317:     m_area = 0;
Chris@317:     for (int i = 0; i < n; ++i) {
Chris@317:         m_area += m_cache[i];
Chris@317:     }
Chris@317:     m_area /= n;
Chris@317: }
Chris@317: 
Chris@317: template <typename T>
Chris@317: void Window<T>::cosinewin(T *mult, T a0, T a1, T a2, T a3)
Chris@317: {
Chris@317:     int n = int(m_size);
Chris@317:     for (int i = 0; i < n; ++i) {
Chris@317:         mult[i] *= (a0
Chris@317:                     - a1 * cos((2 * M_PI * i) / n)
Chris@317:                     + a2 * cos((4 * M_PI * i) / n)
Chris@317:                     - a3 * cos((6 * M_PI * i) / n));
Chris@317:     }
Chris@317: }
Chris@317: 
Chris@317: _VAMP_SDK_HOSTSPACE_END(Window.h)
Chris@317: 
Chris@317: #endif