So I have an animated grid of squares that are masks of a comp that has footage in it. I want to be able to create a slider that I can set to a a value in seconds to determine the length of the animation. So I would set it to 2 and the animation would go from the original 10 seconds to 2 seconds. The tricky part I'm finding is being able to adjust the keyframes without the layers because I don't want the footage within the squares to speed up.
Essentially I want to be able to adjust the length of an animation at the keyframe level to avoid affecting the footage. The reason is that what it is being used for can have different lengths of footage and I want to be able to adjust the animation to speed up or slow down to accommodate the length of the footage without affecting the footage speed.
My initial thought was to time stretch in a "Parent Comp" and just link the positions of all my squares in an identical "Child Comp" but I would rather it be a layer control than have the artist I will be giving it to having to select all of the layers and time stretch them in an alternate comp.