Filter hysteresis
  Grow first stream into second stream by connecting components.
    Inputs:
       #0: base (video)
       #1: alt (video)
    Outputs:
       #0: default (video)
hysteresis AVOptions:
  planes            <int>        ..FV.... set planes (from 0 to 15) (default 15)
  threshold         <int>        ..FV.... set threshold (from 0 to 65535) (default 0)

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

