afftfilt

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.

It accepts the following values:

'w16'

'w32'

'w64'

'w128'

'w256'

'w512'

'w1024'

'w2048'

'w4096'

'w8192'

'w16384'

'w32768'

'w65536'

Default is w4096

'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.