Filter asubcut
  Cut subwoofer frequencies.
    slice threading supported
    Inputs:
       #0: default (audio)
    Outputs:
       #0: default (audio)
asubcut AVOptions:
  cutoff            <double>     ..F.A....T. set cutoff frequency (from 2 to 200) (default 20)
  order             <int>        ..F.A....T. set filter order (from 3 to 20) (default 10)
  level             <double>     ..F.A....T. set input level (from 0 to 1) (default 1)

This filter has support for timeline through the 'enable' option.

