Filter histogram
  Compute and draw a histogram.
    Inputs:
       #0: default (video)
    Outputs:
       #0: default (video)
histogram AVOptions:
  level_height      <int>        ..FV..... set level height (from 50 to 2048) (default 200)
  scale_height      <int>        ..FV..... set scale height (from 0 to 40) (default 12)
  display_mode      <int>        ..FV..... set display mode (from 0 to 2) (default stack)
     overlay         0            ..FV.....
     parade          1            ..FV.....
     stack           2            ..FV.....
  d                 <int>        ..FV..... set display mode (from 0 to 2) (default stack)
     overlay         0            ..FV.....
     parade          1            ..FV.....
     stack           2            ..FV.....
  levels_mode       <int>        ..FV..... set levels mode (from 0 to 1) (default linear)
     linear          0            ..FV.....
     logarithmic     1            ..FV.....
  m                 <int>        ..FV..... set levels mode (from 0 to 1) (default linear)
     linear          0            ..FV.....
     logarithmic     1            ..FV.....
  components        <int>        ..FV..... set color components to display (from 1 to 15) (default 7)
  c                 <int>        ..FV..... set color components to display (from 1 to 15) (default 7)
  fgopacity         <float>      ..FV..... set foreground opacity (from 0 to 1) (default 0.7)
  f                 <float>      ..FV..... set foreground opacity (from 0 to 1) (default 0.7)
  bgopacity         <float>      ..FV..... set background opacity (from 0 to 1) (default 0.5)
  b                 <float>      ..FV..... set background opacity (from 0 to 1) (default 0.5)


