[FFmpeg-user] Ffmpeg - h filter

[James Northrup]

i am maintaining ffblockly which scrapes the ffmpeg executable for filter
parameters and defaults by cartesian product of e.g. >>>(below)

is there a build step artifact that more cleanly has the  self-doc
records?  this cmdline help has changed ever so slightly and i've got to
reverse engineer again.  my initial look into the build process turned up
nothing conclusive, maybe some hints to get me started looking in the right
place

>>>(below)
ffmpeg -h filter=crop 2>/dev/null
Filter crop
 Crop the input video.
   Inputs:
      #0: default (video)
   Outputs:
      #0: default (video)
crop AVOptions:
 out_w             <string>     ..FV.....T set the width crop area
expression (default "iw")
 w                 <string>     ..FV.....T set the width crop area
expression (default "iw")
 out_h             <string>     ..FV.....T set the height crop area
expression (default "ih")
 h                 <string>     ..FV.....T set the height crop area
expression (default "ih")
 x                 <string>     ..FV.....T set the x crop area expression
(default "(in_w-out_w)/2")
 y                 <string>     ..FV.....T set the y crop area expression
(default "(in_h-out_h)/2")
 keep_aspect       <boolean>    ..FV...... keep aspect ratio (default
false)
 exact             <boolean>    ..FV...... do exact cropping (default false)