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)

framesync AVOptions:
  eof_action        <int>        ..FV..... Action to take when encountering EOF from secondary input  (from 0 to 2) (default repeat)
     repeat          0            ..FV..... Repeat the previous frame.
     endall          1            ..FV..... End both streams.
     pass            2            ..FV..... Pass through the main input.
  shortest          <boolean>    ..FV..... force termination when the shortest input terminates (default false)
  repeatlast        <boolean>    ..FV..... extend last frame of secondary streams beyond EOF (default true)

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

