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Keeping animation speed constant when comp is nested & timestretched

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Andrei Mihailescu
Keeping animation speed constant when comp is nested & timestretched
on May 2, 2019 at 3:39:36 pm

So, basically I was stumped today by something which sound simple at first, but I couldn't figure out a way to implement it: we want to use the new responsive design feature in AE to make an Essential Graphics template which animates in and out with a predefined speed (easily done with protected ranges), can be shortened or extended in a PPro timeline as required and - here comes the tricky part - has in the background a permanently rotating element which should keep rotating at the same speed no matter how long the EG clip is.

As far as I can tell by poking around, the only way to achieve something like this in principle would be to drive the rotation of the element by the actual time of a generic parent composition (in this case, the PPro timeline), so that it doesn't slow down & speed up when entering/exiting from/to the protected ranges - but as far as I can tell, you can't actually target this via expressions.

Or am I having a 'derp' moment and ignore something patently obvious?


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Filip Vandueren
Re: Keeping animation speed constant when comp is nested & timestretched
on May 6, 2019 at 8:25:36 am

That's correct.

You can't have an expression target "the time of whatever comp I'm being deployed in" because it could be used at multiple times and in multiple comps, that would mean ambiguous results.

Furthermore, if you would find a way to target that parent-comp, the comp itself does not have a time-property, it is a global property.

Furthermore, if you would make a fake timer (a slider with expression "time;" for example), even explicitly referencing that slider will get its value at the current time of the precomp: same effect: it slows down…

I guess you'll just need to split up your essential graphics template in two layers: one with intro and outro, and one with the rotating element that you simply fade in/out in premiere.

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Andrei Mihailescu
Re: Keeping animation speed constant when comp is nested & timestretched
on May 6, 2019 at 2:38:41 pm

Yeah, I kinda expected / feared this, but wanted to make sure we didn't miss anything obvious.

The split-up idea doesn't quite work in our case, due to how the elements are composited together, so we'll have to give up on the EG template and do everything in After Effects as individual comps.

Perhaps Adobe will consider an option/switch to make specific animation tracks or expressions "responsive" (i.e. not influenced by time stretching). Not sure how that could work exactly, but I guess I should make a feature suggestion, maybe others would find this kind of thing useful as well.

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