Editing with frames over footage - split into 3 triangles??

[Alan_Silvester]

I'm looking for the best workflow to create a split screen effect. It's quite basic in that I want to divide my screen (1080 25p) into 3 segments all playing different streams of video. The segments will be 3 triangles, all tessellated together (see example). I can construct the frames and footage in After Effects but it's not that simple to play with the timing of the clips. I want to edit each of the 3 segments to music and time each cut to trigger the other. It can be done in After Effects but it's clunky

I'd much prefer to do this in Premiere. Is there a simple way to make some alpha channel frames in photoshop or some simple mask technique that I can layer in my Premiere timeline, so I can simple edit with 3 video tracks but knowing each of the 3 will only effect each triangle?

Hope that makes sense.

Cheers

Example for frames (video in each of the 3 triangles.

[Peru Bob]

Create the triangles in Photoshop and use the track matte effect.