Filter drawgrid
  Draw a colored grid on the input video.
    Inputs:
       #0: default (video)
    Outputs:
       #0: default (video)
drawgrid AVOptions:
  x                 <string>     ..FV.... set horizontal offset (default "0")
  y                 <string>     ..FV.... set vertical offset (default "0")
  width             <string>     ..FV.... set width of grid cell (default "0")
  w                 <string>     ..FV.... set width of grid cell (default "0")
  height            <string>     ..FV.... set height of grid cell (default "0")
  h                 <string>     ..FV.... set height of grid cell (default "0")
  color             <string>     ..FV.... set color of the grid (default "black")
  c                 <string>     ..FV.... set color of the grid (default "black")
  thickness         <string>     ..FV.... set grid line thickness (default "1")
  t                 <string>     ..FV.... set grid line thickness (default "1")

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

