Apply an arbitrary Infinite Impulse Response filter.

It accepts the following parameters:

zeros, z

Set B/numerator/zeros/reflection coefficients.

poles, p

Set A/denominator/poles/ladder coefficients.

gains, k

Set channels gains.

dry_gain

Set input gain.

wet_gain

Set output gain.

format, f

Set coefficients format.

ll

lattice-ladder function

sf

analog transfer function

tf

digital transfer function

zp

Z-plane zeros/poles, cartesian (default)

pr

Z-plane zeros/poles, polar radians

pd

Z-plane zeros/poles, polar degrees

sp

S-plane zeros/poles

process, r

Set type of processing.

d

direct processing

s

serial processing

p

parallel processing

precision, e

Set filtering precision.

dbl

double-precision floating-point (default)

flt

single-precision floating-point

i32

32-bit integers

i16

16-bit integers

normalize, n

Normalize filter coefficients, by default is enabled. Enabling it will normalize magnitude response at DC to 0dB.

mix

How much to use filtered signal in output. Default is 1. Range is between 0 and 1.

response

Show IR frequency response, magnitude(magenta), phase(green) and group delay(yellow) in additional video stream. By default it is disabled.

channel

Set for which IR channel to display frequency response. By default is first channel displayed. This option is used only when response is enabled.

size

Set video stream size. This option is used only when response is enabled.

Coefficients in tf and sf format are separated by spaces and are in ascending order.

Coefficients in zp format are separated by spaces and order of coefficients doesn’t matter. Coefficients in zp format are complex numbers with i imaginary unit.

Different coefficients and gains can be provided for every channel, in such case use ’|’ to separate coefficients or gains. Last provided coefficients will be used for all remaining channels.