Filter dilation
  Apply dilation effect.
    slice threading supported
    Inputs:
       #0: default (video)
    Outputs:
       #0: default (video)
dilation AVOptions:
  threshold0        <int>        ..FV..... set threshold for 1st plane (from 0 to 65535) (default 65535)
  threshold1        <int>        ..FV..... set threshold for 2nd plane (from 0 to 65535) (default 65535)
  threshold2        <int>        ..FV..... set threshold for 3rd plane (from 0 to 65535) (default 65535)
  threshold3        <int>        ..FV..... set threshold for 4th plane (from 0 to 65535) (default 65535)
  coordinates       <int>        ..FV..... set coordinates (from 0 to 255) (default 255)

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

