New zoom level: balanced crop

[Noitarud]

I love math, so I devised a formula to discover the scale required to make the image crop-off area be the same as the black bar area. Would you like to include it in your app?

scale=2xy/(vx+hy) XY are for screen and HV are for video image

The only improvment I could still do was to specify ratio of black:crop (presently is 1:1) which is really only necessary if the video ratio is similar to screen except displayed perpendicular.