 
 
	 
In file ../include/sigpr/EST_Window.h:
| class EST_Window | 
The EST_Window class provides functions for the creation and use of signal processing windows.
| ![[more]](icon1.gif)  | Functions for making windows. 
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| ![[more]](icon1.gif)  | Performing windowing on a section of speech. 
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| ![[more]](icon1.gif)  | Utility window functions. 
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| ![[more]](icon1.gif) typedef  EST_WindowFunc | Func A function which creates a window | 
The EST_Window class provides functions for the creation and use of signal processing windows.Signal processing algorithms often work by on small sections of the speech waveform known as frames. A full signal must first be divided into these frames before these algroithms can work. While it would be simple to just "cut out" the required frames from the waveforms, this is usually undesirable as large discontinuities can occur at the frame edges. Instead it is customary to cut out the frame by means of a {em window} function, which tapers the signal in the frame so that it has high values in the middle and low or zero values near the frame edges. The EST_Window class provides a wrap around for such windowing operations.
There are several types of window function, including:
- Rectangular, which is used to give a simple copy of the the values between the window limits.
- Hanning. The rectangular window can cause sharp discontinuities at window edges. The hanning window solves this by ensuring that the window edges taper to 0.
- Hamming. The hanning window causes considerable energy loss, which the hamming window attempts to rectify.
The particular choice of window depends on the application. For instance in most speech synthesis applications Hanning windows are the most suitable as they don't have time domain discontinuities. For analysis applications hamming windows are normally used.
For example code, see Windowing
 typedef  EST_WindowFunc Func
typedef  EST_WindowFunc Func
 Functions for making windows.
 Functions for making windows.
 static   void make_window(EST_TBuffer<float> &window_vals, int size, const char* name)
static   void make_window(EST_TBuffer<float> &window_vals, int size, const char* name)
 static   void make_window(EST_FVector &window_vals, int size, const char* name)
static   void make_window(EST_FVector &window_vals, int size, const char* name)
 static   Func* creator(const char* name, bool report_error = false)
static   Func* creator(const char* name, bool report_error = false)
 Performing windowing on a section of speech.
 Performing windowing on a section of speech. 
 static   void window_signal(const EST_Wave &sig, EST_WindowFunc* make_window, int start, int size, EST_TBuffer<float> &frame)
static   void window_signal(const EST_Wave &sig, EST_WindowFunc* make_window, int start, int size, EST_TBuffer<float> &frame)
 static   void window_signal(const EST_Wave &sig, EST_WindowFunc* make_window, int start, int size, EST_FVector &frame, int resize=0)
static   void window_signal(const EST_Wave &sig, EST_WindowFunc* make_window, int start, int size, EST_FVector &frame, int resize=0)
 static   void window_signal(const EST_Wave &sig, const EST_String &window_name, int start, int size, EST_FVector &frame, int resize=0)
static   void window_signal(const EST_Wave &sig, const EST_String &window_name, int start, int size, EST_FVector &frame, int resize=0)
 static   void window_signal(const EST_Wave &sig, EST_TBuffer<float> &window_vals, int start, int size, EST_FVector &frame, int resize=0)
static   void window_signal(const EST_Wave &sig, EST_TBuffer<float> &window_vals, int start, int size, EST_FVector &frame, int resize=0)
 Utility window functions.
 Utility window functions.
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This page is part of the 
Edinburgh Speech Tools Library documentation
Copyright  University of Edinburgh 1997
Contact:  
         speech_tools@cstr.ed.ac.uk