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EST_filter_design.h
/*************************************************************************/
/* */
/* Centre for Speech Technology Research */
/* University of Edinburgh, UK */
/* Copyright (c) 1995,1996 */
/* All Rights Reserved. */
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/* conditions and the following disclaimer. */
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/*************************************************************************/
#ifndef __EST_FILTER_DESIGN_H__
#define __EST_FILTER_DESIGN_H__
#include "EST_Wave.h"
#include "EST_FMatrix.h"
#include "EST_Track.h"
/**@name Filter Design
FIR Filtering is a 2 stage process, first involving design and then
the filtering itself. As the design is somewhat costly, it is usually
desirable to design a filter outside the main loop.
For one off filtering operations, functions are
provided which design and filter the waveform in a single go.
It is impossible to design an ideal filter, i.e. one which exactly
obeys the desired frequency response. The "quality" of a filter is
given by the order parameter, with high values indicating good
approximations to desired responses. High orders are slower. The
default is 199 which gives a pretty good filter, but a value as low as
19 is still usable if speech is important.
*/
//@{
/** Create an arbitrary filter or order {\tt order} that attempts to
give the frequency response given by {\tt freq_response}. The vector
{\tt freq_response} should be any size 2**N and contain a plot of the
desired frequency response with values ranging between 0.0 and
1.0. The actual filtering is done by \Ref{FIRfilter}.
@see design_lowpass_FIR_filter, design_highpass_FIR_filter
@see FIRfilter, FIRlowpass_filter, FIRhighpass_filter
*/
EST_FVector design_FIR_filter(const EST_FVector &freq_response, int
filter_order);
/** Design a FIR lowpass filter of order {\tt order} and cut-off
frequency {\tt freq}. The filter coefficients are returned in the
FVector and should be used in conjunction with \Ref{FIRfilter}.
@see design_FIR_filter, design_highpass_FIR_filter, FIRfilter,
FIRlowpass_filter, FIRhighpass_filter
*/
EST_FVector design_lowpass_FIR_filter(int sample_rate, int freq, int
order);
/** Design a FIR highpass filter of order {\tt order} and cut-off frequency
{\tt freq}. The filter coefficients are returned in the FVector and should be used in conjunction with \Ref{FIRfilter}
@see design_FIR_filter, design_lowpass_FIR_filter, design_highpass_FIR_filter
@see FIRfilter, FIRlowpass_filter, FIRhighpass_filter
*/
EST_FVector design_highpass_FIR_filter(int sample_rate, int
freq, int order);
//@}
#endif /* __EST_FILTER_DESIGN_H__ */
EST_FVector
Definition EST_FMatrix.h:114