🚀 go-pugleaf

Hi,

I'm interested in constructing a circuit to place in line while
dubbing video between two standard NTSC VHS VCR's that would allow
variable cropping of the image for a "letterboxed" effect.  There would
be two potentiometers (top and bottom) that would control how far the
black borders extend into the image, with a range of "no black at all"
to "black extends nearly to center of picture".  This would make it easy
to experiment with shooting video in different aspect ratios, ie. 1:1.85,
1:2.33.  (The original video would be shot full frame just like film;
I would impose the hard matte when editing or for final playback.)

I'm sure this effect can be achieved with computer overlay boards, Amigas,
and consumer-level editing/effects consoles, but I don't have any of these,
and a limited income.  Is this a doable project?  Has it been done before?

The frequencies aren't too high, so couldn't the top bar be done by
cutting out the luminance for an adjustable time period after each 
vertical blank?  The bottom bar could be controlled by an adjustable 
delay from the last vertical blank until the black begins (cut luma),
after which the luma would remain cut until the cycle repeats.

It would be nice to have the black begin at horizontal sync to avoid a
jagged edge, but this isn't ESSENTIAL.


Comments?  Suggestions?


Mark Fontana