Filter maskfun
  Create Mask.
    slice threading supported
    Inputs:
       #0: default (video)
    Outputs:
       #0: default (video)
maskfun AVOptions:
  low               <int>        ..FV..... set low threshold (from 0 to 65535) (default 10)
  high              <int>        ..FV..... set high threshold (from 0 to 65535) (default 10)
  planes            <int>        ..FV..... set planes (from 0 to 15) (default 15)
  fill              <int>        ..FV..... set fill value (from 0 to 65535) (default 0)
  sum               <int>        ..FV..... set sum value (from 0 to 65535) (default 10)

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

