How to have one clip masked by another, or a shape?

Hello All,

I may not be using the correct terms in the subject, but basically what I want is for a clip to only show part of its content, as defined by a given shape ("Mask"? or "Matte"?). For instance, say my clip is a 800x600 rectangular region, but I want only a 100x100 circular region of it shown. Furthermore, if I were to transition the rectangular region "underneath" the circular region, the circular region would not move but show a different part of the underlying clip through it.

I thought this would be trivial, but I'm having a hard time figuring it out (perhaps because I'm confusing my terms). Thanks!

First you need the circular shape to define the mask. You put that on top and to it you apply blend mode silhouette or stencil alpha in the Video inspector depending on what you need to do. If you only want to effect two layers the matte and one layer, combined them into a compound clip.

scotopia wrote: Furthermore, if I were to transition the rectangular region "underneath" the circular region, the circular region would not move but show a different part of the underlying clip through it.

you can use Transform to reposition the second clip to align the region you want in the circle mask.

Thanks guys; nailed it.