view base/Window.h @ 1008:d9e0e59a1581

When using an aggregate model to pass data to a transform, zero-pad the shorter input to the duration of the longer rather than truncating the longer. (This is better behaviour for e.g. MATCH, and in any case the code was previously truncating incorrectly and ending up with garbage data at the end.)

/* -*- 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 <string>
#include <map>
#include <cstdlib>

#include <cstdlib>

enum WindowType {
    RectangularWindow,
    BartlettWindow,
    HammingWindow,
    HanningWindow,
    BlackmanWindow,
    GaussianWindow,
    ParzenWindow,
    NuttallWindow,
    BlackmanHarrisWindow
};

template <typename T>
class Window
{
public:
    /**
     * Construct a windower of the given type and size. 
     *
     * Note that the cosine windows are periodic by design, rather
     * than symmetrical. (A window of size N is equivalent to a
     * symmetrical window of size N+1 with the final element missing.)
     */
    Window(WindowType type, int 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 (int i = 0; i < m_size; ++i) dst[i] = src[i] * m_cache[i];
    }

    T getArea() { return m_area; }
    T getValue(int i) { return m_cache[i]; }

    WindowType getType() const { return m_type; }
    int getSize() const { return m_size; }

    // The names used by these functions are un-translated, for use in
    // e.g. XML I/O.  Use Preferences::getPropertyValueLabel if you
    // want translated names for use in the user interface.
    static std::string getNameForType(WindowType type);
    static WindowType getTypeForName(std::string name);

protected:
    WindowType m_type;
    int m_size;
    T *m_cache;
    T m_area;
    
    void encache();
    void cosinewin(T *, T, T, T, T);
};

template <typename T>
void Window<T>::encache()
{
    const int n = 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)
{
    const int n = 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));
    }
}

template <typename T>
std::string
Window<T>::getNameForType(WindowType type)
{
    switch (type) {
    case RectangularWindow:    return "rectangular";
    case BartlettWindow:       return "bartlett";
    case HammingWindow:        return "hamming";
    case HanningWindow:        return "hanning";
    case BlackmanWindow:       return "blackman";
    case GaussianWindow:       return "gaussian";
    case ParzenWindow:         return "parzen";
    case NuttallWindow:        return "nuttall";
    case BlackmanHarrisWindow: return "blackman-harris";
    }

    std::cerr << "WARNING: Window::getNameForType: unknown type "
              << type << std::endl;

    return "unknown";
}

template <typename T>
WindowType
Window<T>::getTypeForName(std::string name)
{
    if (name == "rectangular")     return RectangularWindow;
    if (name == "bartlett")        return BartlettWindow;
    if (name == "hamming")         return HammingWindow;
    if (name == "hanning")         return HanningWindow;
    if (name == "blackman")        return BlackmanWindow;
    if (name == "gaussian")        return GaussianWindow;
    if (name == "parzen")          return ParzenWindow;
    if (name == "nuttall")         return NuttallWindow;
    if (name == "blackman-harris") return BlackmanHarrisWindow;

    std::cerr << "WARNING: Window::getTypeForName: unknown name \""
              << name << "\", defaulting to \"hanning\"" << std::endl;

    return HanningWindow;
}

#endif