Custom "Crop"

I have a lot of videos that have an aspect ratio of 2.40:1 which means they play in a narrow band in the center of my iPad screen.  The "crop" zoom mode, crops too much.  I would like to be able to customize the crop, so that it just takes a little off the sides (bringing my vertical resolution to 768 preferably) and there is still a black bar at top and bottom, just not as much of one.  I would be fine if there were 2 or 3 choices in the "crop" zoom mode so it doesn't really have to be customizable, just something other than all or none.