Filter arealtime
  Slow down filtering to match realtime.
    Inputs:
       #0: default (audio)
    Outputs:
       #0: default (audio)
arealtime AVOptions:
  limit             <duration>   ..FVA.... sleep time limit (default 2)
  speed             <double>     ..FVA.... speed factor (from DBL_MIN to DBL_MAX) (default 1)


