Stop motion animation and audio keyframes in AE so I'm completely new to After Effects (normally work with premiere or stop motion animation) so if I've not given enough/or the right information, just let me know what you need to know.

I have a four frame animation, and want to use keyframes generated by audio to choose which frame to show of the animation (it's for a music video and each frame is a different position while playing an instrument). I was hoping to assign a frame to different value ranges generated by the audio, I've managed to animate other things with audio keyframes and linear expressions. The issue I seem to be having is that keyframes seem to only exist for effects, so I can't figure out how to assign each frame of the animation a value that I can then use in relation to the generated keyframes.

I'm sorry if that doesn't make any sense, but any help would be hugely appreciated!
You can choose which frame of footage is shown by enabling Time Remapping for the layer. Find it in the layer menu, or by right-clicking a layer in the timeline, or by using ctrl / ⌘alt / ⌥t



Turn it on for a layer and the displayed time is set by the value of the Time Remap property, which can be keyframed or controlled with expressions. Once you've applied it hit u to show it.



The value of the property is in in seconds, so you'll have to convert it to frames. You'll have to check what fps value the footage is interpreted as having.