Filter fillborders
  Fill borders of the input video.
    Inputs:
       #0: default (video)
    Outputs:
       #0: default (video)
fillborders AVOptions:
  left              <int>        ..FV..... set the left fill border (from 0 to INT_MAX) (default 0)
  right             <int>        ..FV..... set the right fill border (from 0 to INT_MAX) (default 0)
  top               <int>        ..FV..... set the top fill border (from 0 to INT_MAX) (default 0)
  bottom            <int>        ..FV..... set the bottom fill border (from 0 to INT_MAX) (default 0)
  mode              <int>        ..FV..... set the fill borders mode (from 0 to 2) (default smear)
     smear           0            ..FV.....
     mirror          1            ..FV.....
     fixed           2            ..FV.....
  color             <color>      ..FV..... set the color for the fixed mode (default "black")

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

