Apply arbitrary expressions to samples in frequency domain.

real

Set frequency domain real expression for each separate channel separated by ’|’. Default is "re". If the number of input channels is greater than the number of expressions, the last specified expression is used for the remaining output channels.

imag

Set frequency domain imaginary expression for each separate channel separated by ’|’. Default is "im".

Each expression in real and imag can contain the following constants and functions:

sr

sample rate

b

current frequency bin number

nb

number of available bins

ch

channel number of the current expression

chs

number of channels

pts

current frame pts

re

current real part of frequency bin of current channel

im

current imaginary part of frequency bin of current channel

real(b, ch)

Return the value of real part of frequency bin at location (bin,channel)

imag(b, ch)

Return the value of imaginary part of frequency bin at location (bin,channel)

win_size

Set window size. Allowed range is from 16 to 131072. Default is 4096

win_func

Set window function. Default is hann.

overlap

Set window overlap. If set to 1, the recommended overlap for selected window function will be picked. Default is 0.75.