The untangled wonkyness of pasting AE transform effect keyframes into PR
A few users have mentioned the secret but awesome ability to copy AE layers with their properties, keyframes and even sometimes effects directly into PR with the usual CMND/CNTR+C on the layer in AE and CMND/CNTRL+V in a sequence in PR. In fact the great Jarle of Jarle's presets told me this is how he made his awesome "deadpool camera shake presets for PR" by tracking real camera shake in AE then copying the layer with motion keyframes into PR and saving the motion properties as PR presets.
But I thought I'd take this one step further and use the Transform effect for similar camera shake presets since it is more versatile and can even be applied to adjustment layers in order to shake everything below. I copied a layer from AE that had been animated using the wiggle expression and then used the convert expression to keyframes option and then tried copy/pasting that layer into PR. It worked and the effect carried over but the values which in AE were bouncing around 1920x1080 (the center for a 4K video) had simply become .5 and .5 in PR. Anyway after many hours of deconstructing the strange translation of this data from AE to PR I figured out what goes wrong and it's probably just a bit of buggy code in how PR handles the information from AE in combination with the way it attempts to adapt the values of an affect on a layer of one size to a layer of a different size. Below I have some math that explains it the best I can. I hope this helps, I saved my keyframes in the end as a preset using the transform effect.
When you copy a layer from AE to PR its base level transform/motion properties translate objectively and correctly (hence why it was easy for Jarle to make his presets using those properties). BUT when you copy and paste the Transform EFFECT (an effect that exists in AE & PR) from a clip of one dimension to a clip of another dimension in Premiere it tries to adjust the values with a change relative to the difference between source and destination dimensions. So if your destination clip is smaller than your source for example, the transform adjustments are similarly smaller on the pasted clip than they were on the source.
The math for this is not too complicated, PR basically turns the values of the transform effect on the source clip into a percentage of its source dimensions and multiplies those by the destination dimensions.
(Source clip EFFECT x,y ÷ source layer DIMENSIONS x,y ) X (destination layer DIMENSIONS x,y)
BUT when you go from AE to PR it screws things up because it adds an extra permutation (highlighted here between **)
(AE Source Layer EFFECT x,y ÷ AE source layer DIMENSIONS x,y) X (PR destination layer dimensions) ÷ (AE source layer dimensions)
It's almost as if PR starts to repeat the original permutation again.
If innocently you think having an AE source layer with a width of 3840 and a transform effect X-value of 1920 in AE will get you a transform effect in PR also with a value of 1920 you will be upset to find what you will really get is:
1920 ÷ 3840 =.5
.5 x 3840 =1920
1920 ÷ 3840 = .5
The solution I found is to basically reduce the layer in AE to 1px and use a transform of .5. This gives me
.5 ÷ 1 = .5
.5 x 3840 =1920
1920 ÷ 1=1920
Then I did the whole wiggle expression in AE, turned it into keyframes, copied the clip into PR and it worked.
If you have a more elegant explanation or solution to reversing this translation error please let me know!
Also ADOBE PLEASE FIX THIS LITTLE BUG IT WOULD BE A HUGE HELP thanks!