EST_filter_design.h

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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"

/**@defgroup FilterDesign 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 `order` that attempts to
give the frequency response given by `freq_response`. The vector
`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  `order` and cut-off
frequency `freq`. The filter coefficients are returned in the
EST_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 `order` and cut-off frequency
`freq`. The filter coefficients are returned in the EST_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__ */