I'm poking around for a way to manually control a property of a layer in real-time, like you might do with pitch, playback speed, and volume on a MIDI controller. Ideally, I'd like for AfterEffects to capture the changes as keyframes, or something like that. I'd love to be able to drag a scrubber, or draw on a canvas with a stylus, and have AE translate those real-time movements into changes in clip properties.
I don't have a lot of experience with expressions, but I know how to write code. I think, with some research, I can get this to happen by using the Write-On effect, drawing on a canvas with the stylus, and then linking various properties to the X and Y coordinates of the brush. This is a decent partial solution -- at least I could capture organic movement and apply it to these properties, so I wasn't so hung up working with curves and Eases and quirky intermediate keyframes.
But it would be awesome if there was a plugin... or some precedent technique or expression... that would let me preview the clip in real time at a low resolution, and then use the stylus or mouse to capture movement as I watched. It would be a great tool for syncing certain properties to a soundtrack, creating complex and organic animations, stuff like that. I'd love to be able to do this with the TimeWarp property, and preview it as I went along.
"Changing properties" and "Controlling behavior" plus "Real-time" didn't come up with anything relevant, either here or in Google. Anyone have any leads as to how this type of thing might be achieved?