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time remap and masks??
Hi,
This is my second day in After Effects and I love it! My new favourite app.
I’ve just completed my first rotoscoping project: a mask that changes frame by frame to cut out a moving object and put it on a new background.
But now I want to time remap my video clip. When I do so, the video clip itself remaps fine, but the mask doesn’t get changed and thus it no longer masks the right areas at the right time in the clip.
Is there a way to lock the mask to the frames so that when I do a time remap the mask is remapped along with the video frames?
Thanks in advance!
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4 Replies
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No, there’s really not a way to tie the time remapping values to your mask keyframes. (Well, maybe with expressions, but that’s a discussion for another day.)
What you can do is stretch out your mask keyframes to match the new timing. Select all of the keyframes, then hold down the ALT (Option on Mac) key and click and drag the last keyframe until they’ve stretched where they need to be. If it’s more appropriate, you can also drag the first keyframe.
Depending on how exactly you remapped time and how many keyframes you have, you may need to adjust some keyframes manually. Double-check. For the future, and you’ve probably already realized this, it’s easier to wait until after you’ve done time remapping to apply most other effects.
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Hi Tim,
Thanks for the reply. Yeah, I have realised now to do timing first, effects second.
The other thing I read on another forum is to do a pre-comp. Now that layer and it’s mask is in another composition, and in my main composition I can apply the time remap and the mask (which is now an alpha channel) is locked to the video frames.
-CK
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Pre-comping is the way around a lot of ‘gotchas.’
In terms of SIMPLE math, most people get the following calculation wrong:
2 + 3 * 5.The correct answer is 17 because you multiply before you add, but most people add the 2 + 3 first and come up with 25. The following makes the correct answer more clear:
2 + (3 * 5).Pre-comping is like putting the parentheses around a calculation to do it first and then do something with the result. Example:
time remap * (video – masked area)
masks the video THEN time remaps it.Jim Kanter,
Digital Film Institute
http://www.dfilminst.com -
Duh… pre-comping. Where’s my brain at this week?
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