Expression Oddity – not reading keyframes across compositions.

[Jamie Bradshaw]

Oops forgot to mention that I am using CS5 10.0.0.458 if that is any help.

JimJam•Graphics
https://www.jimjamgraphics.com/

[Ben Rollason]

You’ve probably time offset the layer in the top comp.

try:

L = comp(“top comp”).layer(“layer whatever”); //the layer with this comp as source
T = time + L.startTime;
this.position = L.position.valueAtTime(T);

-Ben.

vfx.benrollason.com

[Todd Kopriva]

> I am using CS5 10.0.0.458

I strongly recommend installing the After Effects CS5 (10.0.1) update. That update fixes a lot of problems.

———————————————————————————————————
Todd Kopriva, Adobe Systems Incorporated
Technical Support for professional video software
After Effects Help & Support
Premiere Pro Help & Support
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[Jan Sickinger]

i had the same problem. the answer was the time-problem.

https://forums.creativecow.net/thread/227/17733#17738

going to try ben´s solution.

thanks everyone, jan

[John Cooper]

I am having a similar problem and after reading through this thread, I don’t fully understand what’s going on.

main_comp contains:
scene_comp contains:
object_comp contains:
object_layer

object_layer opacity is set with the following expression:
comp(“main_comp”).layer(“Audio Amplitude”)(“Slider”)

I can confirm that this expression works by watching the value of opacity of object_layer as I scrub across the main_comp’s timeline where the audio amplitude changes (after time 1;00;00).

Problem: When I place the scene_comp at time 1;00;00 (where the audio amplitude values actually change), the opacity fails to change as expected given the values of the audio amplitude Slider.

Test 1 Succeeds: Placing the scene_comp at time 0 of main_comp and sliding the audio amplitude layer such that the audio amplitude value starts/changes, changes the opacity of of the object_layer as expected.

Test 2 Succeeds: Placing the scene_comp anywhere along the timeline of main_comp and then sliding the audio amplitude layer to the left again until the audio amplitude changes, changes the opacity of object_layer as expected.

Test 3 Fails: Placing the scene_comp anywhere along the timeline of main_comp where the audio amplitude is changing while leaving the audio amplitude layer static fails to change the opacity of the object_layer. This is what I would like to do.

Question A: What is my problem?
Question B: How do I fix it?
Question C: How do I prevent this from occurring in the future?

TIA

comp("main_comp").layer("Audio Amplitude")("Slider")

[Dan Ebberts]

If it’s only the scene comp that’s offset from time zero, I think this will work (not tested–may be typos):

C = comp(“main comp”);
ctrl = C.layer(“Audio Amplitude”)(“Slider”);
ctrl.valueAtTime(time + C.layer(“scene_comp”).startTime)

If other elements are also offset, the valueAtTime() calculation would need to be adjusted accordingly.

Dan

[John Cooper]

Thanks Dan. Worked like a charm. Are the following answers correct, below?

Question A: What is wrong?
Answer: The object layer expression always reads at t=0 of the control source layer.

Question B: How do I fix it?
Answer: Start the object_layers expression at main_comp.time + scene_comp.startTime

Question C: How do I prevent it?
Answer: You can’t prevent it unless all of the comps have exactly the same duration.

[Dan Ebberts]

Answer A: The expression is asking for the value of the slider at the current time of the comp with the expression. If anything in the stack of nested comps between the expression and the slider has been offset in time, that time won’t be correct in the slider comp. Think of it like time zones. If I want to call you at 3PM your time, I need to compensate for any difference in time zones.

Answer B: You have to compensate for any time offsets in the nested comp stack.

Answer C: It’s not the duration that matters, it’s the relative start times. If everything starts at time = 0 (same time zones), no problem.

Dan