Here’s the hypothetical scenario: I have a scene with 100 objects. I add a new movie in the VSE to make a movie strip. I add the scene over the top of that channel and set its ray tracing alpha to transparency so it renders over the top of the movie. The scene strip is also set to alpha over.
What I want to do is fade the scene out to alpha zero. The only way I can figure out how to do that is to keyframe 100 objects (or group them or whatever) to fade the alpha out.
What I’ve tried: create a new scene with no objects, call it “alpha”. Make a cross fade between my scene and the alpha scene over the top of the movie strip. Outcome is that the alpha scene strip replaces everything below making everything below it transparent rather than remaining transparent and leaving the strips underneath intact.
Why am I doing something so crazy? Because I want to use transition effects that are easier to manage with scenes than with keyframing where multiple objects are just getting faded out.
I hope all this makes sense…