biquad.h File Reference

Second order Infinite Impulse Response filter. More...

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Functions
uint_t	aubio_filter_set_biquad (aubio_filter_t *f, lsmp_t b0, lsmp_t b1, lsmp_t b2, lsmp_t a1, lsmp_t a2)
	set coefficients of a biquad filter More...
aubio_filter_t *	new_aubio_filter_biquad (lsmp_t b0, lsmp_t b1, lsmp_t b2, lsmp_t a1, lsmp_t a2)
	create biquad filter with b0, b1, b2, a1, a2 coeffs More...

Detailed Description

Second order Infinite Impulse Response filter.

This file implements a normalised biquad filter (second order IIR):

\( y[n] = b_0 x[n] + b_1 x[n-1] + b_2 x[n-2] - a_1 y[n-1] - a_2 y[n-2] \)

The filtfilt version runs the filter twice, forward and backward, to compensate the phase shifting of the forward operation.

See also Digital biquad filter on wikipedia.

Definition in file biquad.h.

Function Documentation

aubio_filter_set_biquad()

uint_t aubio_filter_set_biquad	(	aubio_filter_t *	f,
		lsmp_t	b0,
		lsmp_t	b1,
		lsmp_t	b2,
		lsmp_t	a1,
		lsmp_t	a2
	)

set coefficients of a biquad filter

Parameters

f	filter object as returned by new_aubio_filter()
b0	forward filter coefficient
b1	forward filter coefficient
b2	forward filter coefficient
a1	feedback filter coefficient
a2	feedback filter coefficient

new_aubio_filter_biquad()

aubio_filter_t* new_aubio_filter_biquad	(	lsmp_t	b0,
		lsmp_t	b1,
		lsmp_t	b2,
		lsmp_t	a1,
		lsmp_t	a2
	)

create biquad filter with b0, b1, b2, a1, a2 coeffs

Parameters

b0	forward filter coefficient
b1	forward filter coefficient
b2	forward filter coefficient
a1	feedback filter coefficient
a2	feedback filter coefficient

Examples:

temporal/test-biquad.c.