Filter bench
  Benchmark part of a filtergraph.
    Inputs:
       #0: default (video)
    Outputs:
       #0: default (video)
bench AVOptions:
  action            <int>        ..FV..... set action (from 0 to 1) (default start)
     start           0            ..FV..... start timer
     stop            1            ..FV..... stop timer


