[magick-users] Thumbnails from first image of an avi

[Jim Kleckner]

I've tried a variety of options for "convert" to extract just the first 
frame of an avi as a thumbnail:
  -scene 0-0
  -thumbnail <geo>
  -flatten

The -flatten works, but scans through the whole avi file as an image 
sequence.

Is there a simple way to just extract that first frame?

Thanks