Active cropping/masking
 

Hi.

I have a thought, and I haven't sat down to try it yet (my machine is busy doing a render) so I thought I would do some research first...

Heres what I'm wondering:

Is there any way to actively crop a video file. For example. If I have a circular shape, and I watch the video playing in the layer behind the circle and use my mouse to move the circle around that video background. Then, the program crops everything outside (or inside) the circle, keyframing its position across the timeline according to where I had it placed then when I was 'tracing' over the video....

Sound crazy?

I realize I could probably create a small vector based shape and use it as mask, animating it using keyframes, but what I was trying to see if I could acheive was the idea of using my hand eye coordination to accomplish cropping in a video file.

I have vegas and premiere (and after effects, but not really).... accessible. Could this be done in any of those proggies?

P.S. Am I crazy for thinking this?

-raza

--edited for clarity--