I am playing a round with music by animating different layers by the use of an expression .
thisComp.layer("Audio Amplitude").effect("Both Channels")("Slider")
I would like to use a Rectangular mask to hide/reveal a layer in a kind of "horizontal music spectrum visualization".
Hence part of the layer will be hidden according to the beats.
I have used the expression in various other properties like opacity, but is it possible to do this for a rectangular mask for its width or length.
Thanks in advance.
Masks cannot be manipulated using expressions. You have to apply it to effects like linear wipe or the scale of a solid and use that as matte. Bothe methods are simple enough and don't require any mask usage, if you realyl just want a rectangle.