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Confussed about time between compositions
Hi Guys,
I thought I was being really clever. I had a layer in a pre-comp with a wipe transition effect on. This pre-comp was nested in side another comp which was the main comp for the project. I wanted to be able to control the wipe transition inside the pre-comp with a slider attached to a layer in the main comp. That was pretty easy and I set keyframes in the main comp to animate the transition. All was good……
Until…..
I wanted to change which part of the pre-comp was showing in the main comp. The pre-comp was actually a video that was about 1:30 long, the main comp is only about 30 seconds. When I started the first frame of the pre-comp was at the first frame of the main comp. The in-point of the pre-comp was about 10 seconds into the main comp and it was only showing for about 10 seconds. I thought I could just slip the footage of the pre-comp in-between the in and out points in the main comp and the transition would still happen at the keyframes. But it didn’t.
I’m guessing that the expression inside the pre-comp uses the time of that composition, rather than the comp it is nested in and looks for values at that time so if I slip the footage a minute in time it will become a minute out of sync of the keyframes.
How can I stop this happening? I would like the transition to happen at the same point in time inside the main composition regardless where I am at the footage inside the pre-comp.
I hope this makes sense.
Thanks,
Conrad
PS I’m out of the office tomorrow so if I don’t reply for a day or so it doesn’t mean I’m not grateful. Thanks.
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4 Replies
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That’s interesting. Must be some kind of caching issue. If you turn the expression off and then back on it should be OK.
Dan
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So what I’d done should have behaved the way I expected? I’ve just spent 20 mins messing with the expression, enabling and disabling it, and couldn’t get it to behave.
If I moved the keyframes around inside the main comp the transition would change, but only when the keyframes were in the wrong place.
I thought I had to get the time of the parent comp and use it inside the pre-comp somehow.
I’ll give After Effects a re-start in a minute and see if it works again.
Thanks for the quick reply.
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Another thing that you can do after you move the clip is Edit > Purge > Image Caches.
Dan
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Hi Dan,
Sorry I didn’t reply sooner but was ill at the end of last week but back in the office now.
I’ve restarted AE (and the computer) and have tried this on a brand new project but I’m still having the same problem. It doesn’t look like a bug or anything, it just looks like I’m doing it wrong.
I’m not sure if I have made my problem clear. I have a wipe transition on a layer inside a pre-comp. This pre comp is longer than the main composition that it is nested in but when I created the expression the first frame of the pre-comp was on the first frame of the main comp. I have keyframed a slider expression control that is on a null layer inside the main composition. These keyframes are synced to something that happens in the main comp and this is where I want the transition to occur.
For example the main comp is 100 frames long and the pre comp is 500 frames long. Frame 0 of the pre comp is at frame 0 in the main comp. The transition starts on frame 10 in the main comp and lasts 10 frames. This works fine. The transition inside the pre comp starts at frame 10.
But if slide the pre comp back 5 frames inside the main comp so that frame 5 of the pre comp is at the first frame in the main comp the transition no longer happens in line with the key frames but starts 5 frames early. I can slide the layers inside the pre comp so that the first frame of the pre comp is still at the first frame of the main comp but I use the pre comp else where in the project so don’t really want to change it.
It seems to me that the expression in the pre comp looks at the position of the keyframe in the main comp (frame 10) and positions it at the same point in the pre comp (frame 10) regardless of whether or not they are at the same point in the main comp.
Hope this makes more sense. Thanks.
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