Filter cellauto
  Create pattern generated by an elementary cellular automaton.
    Inputs:
        none (source filter)
    Outputs:
       #0: default (video)
cellauto AVOptions:
  filename          <string>     ..FV..... read initial pattern from file
  f                 <string>     ..FV..... read initial pattern from file
  pattern           <string>     ..FV..... set initial pattern
  p                 <string>     ..FV..... set initial pattern
  rate              <video_rate> ..FV..... set video rate (default "25")
  r                 <video_rate> ..FV..... set video rate (default "25")
  size              <image_size> ..FV..... set video size
  s                 <image_size> ..FV..... set video size
  rule              <int>        ..FV..... set rule (from 0 to 255) (default 110)
  random_fill_ratio <double>     ..FV..... set fill ratio for filling initial grid randomly (from 0 to 1) (default 0.618034)
  ratio             <double>     ..FV..... set fill ratio for filling initial grid randomly (from 0 to 1) (default 0.618034)
  random_seed       <int>        ..FV..... set the seed for filling the initial grid randomly (from -1 to UINT32_MAX) (default -1)
  seed              <int>        ..FV..... set the seed for filling the initial grid randomly (from -1 to UINT32_MAX) (default -1)
  scroll            <boolean>    ..FV..... scroll pattern downward (default true)
  start_full        <boolean>    ..FV..... start filling the whole video (default false)
  full              <boolean>    ..FV..... start filling the whole video (default true)
  stitch            <boolean>    ..FV..... stitch boundaries (default true)


