The EST_Window class provides functions for the creation and use of signal processing windows. More...

#include <include/sigpr/EST_Window.h>

Public Types
typedef EST_WindowFunc	Func
	A function which creates a window. More...

Static Public Member Functions
Functions for making windows.
static void	make_window (EST_TBuffer< float > &window_vals, int size, const char *name, int window_centre)

static void	make_window (EST_FVector &window_vals, int size, const char *name, int window_centre)

static Func *	creator (const char *name, bool report_error=false)
	Return the creation function for the given window type. More...

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_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)

Utility window functions.
static EST_String	description (const char *name)
	Return the description for a given window type. More...

static EST_String	options_supported (void)
	Return a paragraph describing the available windows. More...

static EST_String	options_short (void)
	Return a comma separated list of the available window types. More...

Detailed Description

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 algorithms 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 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.

$w_{n} = \left\{ \begin{array}{ll} 1 & \mbox{$0 \leq n \leq N$} \\ 0 & \mbox{otherwise} \end{array} \right.$

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.

$w_{n} = \left\{ \begin{array}{ll} 0.5 - 0.5 \cos(2\pi n / (N-1)) & \mbox{$0 \leq n \leq N$} \\ 0 & \mbox{otherwise} \end{array} \right.$

Hamming: The hanning window causes considerable energy loss, which the hamming window attempts to rectify.

$w_{n} = \left\{ \begin{array}{ll} 0.54 - 0.46 \cos(2\pi n / (N-1)) & \mbox{$0 \leq n \leq N$} \\ 0 & \mbox{otherwise} \end{array} \right.$

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

Definition at line 111 of file EST_Window.h.

Member Typedef Documentation

typedef EST_WindowFunc EST_Window::Func

A function which creates a window.

Definition at line 115 of file EST_Window.h.

Member Function Documentation

void EST_Window::make_window	(	EST_TBuffer< float > &	window_vals,
		int	size,
		const char *	name,
		int	window_centre
	)

static

Make a Buffer of containing a window function of specified type. If window_centre < 0 (default -1), then a symmetric window is returned. For positive values of the window_centre argument, asymmetric windows are returned.

Definition at line 259 of file EST_Window.cc.

void EST_Window::make_window	(	EST_FVector &	window_vals,
		int	size,
		const char *	name,
		int	window_centre
	)

static

Make a EST_FVector containing a window function of specified type. If window_centre < 0 (default -1), then a symmetric window is returned. For positive values of the window_centre argument, asymmetric windows are returned.

Definition at line 267 of file EST_Window.cc.

EST_Window::Func * EST_Window::creator	(	const char *	name,
		bool	report_error = `false`
	)

static

Return the creation function for the given window type.

Definition at line 218 of file EST_Window.cc.

void EST_Window::window_signal	(	const EST_Wave &	sig,
		EST_WindowFunc *	make_window,
		int	start,
		int	size,
		EST_TBuffer< float > &	frame
	)

static

Window the waveform sig starting at point start for a duration of size samples. The windowing function required is given as a function pointer *make_window which has already been created by a function such as EST_Window::creator. The output windowed frame is placed in the buffer frame which will have been resized accordingly within the function.

Definition at line 279 of file EST_Window.cc.

void EST_Window::window_signal	(	const EST_Wave &	sig,
		EST_WindowFunc *	make_window,
		int	start,
		int	size,
		EST_FVector &	frame,
		int	resize = `0`
	)

static

Window the waveform sig starting at point start for a duration of size samples. The windowing function required is given as a function pointer *make_window which has already been created by a function such as creator . The output windowed frame is placed in the EST_FVector frame. By default, it is assumed that this is already the correct size (i.e. size samples long), but if resizing is required the last argument should be set to 1.

Definition at line 318 of file EST_Window.cc.

void EST_Window::window_signal	(	const EST_Wave &	sig,
		const EST_String &	window_name,
		int	start,
		int	size,
		EST_FVector &	frame,
		int	resize = `0`
	)

static

Window the waveform sig starting at point start for a duration of size samples. The windowing function required is given as a string: this function will make a temporary window of this type. The output windowed frame is placed in the EST_FVector frame. By default, it is assumed that this is already the correct size (i.e. size samples long), but if resizing is required the last argument should be set to 1.

Definition at line 309 of file EST_Window.cc.

void EST_Window::window_signal	(	const EST_Wave &	sig,
		EST_TBuffer< float > &	window_vals,
		int	start,
		int	size,
		EST_FVector &	frame,
		int	resize = `0`
	)

static

Window the waveform sig starting at point start for a duration of size samples. The window shape required is given as an array of floats. The output windowed frame is placed in the EST_FVector frame. By default, it is assumed that this is already the correct size (i.e. size samples long), but if resizing is required the last argument should be set to 1.

Definition at line 333 of file EST_Window.cc.

EST_String EST_Window::description ( const char * name )

static

Return the description for a given window type.

Definition at line 232 of file EST_Window.cc.

EST_String EST_Window::options_supported ( void )

static

Return a paragraph describing the available windows.

Definition at line 385 of file EST_Window.cc.

EST_String EST_Window::options_short ( void )

static

Return a comma separated list of the available window types.

Definition at line 399 of file EST_Window.cc.

The documentation for this class was generated from the following files:

include/sigpr/EST_Window.h
sigpr/EST_Window.cc

Public Types

Static Public Member Functions

Detailed Description

Member Typedef Documentation

Member Function Documentation