I wish to control the opacity of one clip using the luma of another clip. So for example, completely white parts in clip 1 should result in opacity 100 % in clip 2, grey parts in clip 1 should result in opacity 50 % in clip 2, and black parts in clip 1 should result in opacity 0 % in clip 2 Is this possible?
Experimenting with Track Matte Key has not given satisfactory results. The issue is that the clip I intend to use only for controlling opacity is visible (i.e., the non-black parts show up in the final video). What I desire is that the clip that controls opacity is not visible in any way, it should only control the opacity of that other clip.