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Corrupt Keyframes

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Evan Thompson
Corrupt Keyframes
on Apr 21, 2013 at 6:01:32 pm

Hello COW Community,

I have had this problem many times and it gets really annoying.

When using keyframes in Adobe After Effects CS4 sometimes a space between two keyframes seems to get "a mind of it's own".
In this case the keyframes are controlling a layer's movement. Keyframe "A" and keyframe "B" are many frames apart but have the exact same values. About half way in between the two keyframes the value (position) decides to change itself to a slightly different location and then comes right back in time to have the correct value by the time keyframe "B" comes around. There are no keyframes authorizing this change, and trying to keyframe every frame the same changes the behavior of the problem, but it still finds some way to get it's little "joy ride" in.

What on earth is this all about? I'm assuming this is a little glitch in the software.
This doesn't happen all the time, just on occasion. But when it does, it's hard to get around.

Does anyone know of a cause, a solution or a trick to getting around this?

-Evan


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Joseph W. Bourke
Re: Corrupt Keyframes
on Apr 21, 2013 at 6:42:58 pm

It sounds to me as though these might be Bezier keyframes, and what you're seeing that "seems" to be a bug, is actually the normal movement you would get because of the curve inherent in the Bezier keyframe. Take a look at the properties of the keyframe, and I'll bet that's what you'll see. If you change them to Linear, you won't have any of the problems. You just need to learn about the various types of keyframes, and how they behave. Here's a nice visual guide:

http://greyscalegorilla.com/blog/tutorials/guide-to-keyframes-in-after-effe...

Joe Bourke
Owner/Creative Director
Bourke Media
http://www.bourkemedia.com


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Chris Buttacoli
Re: Corrupt Keyframes
on Apr 21, 2013 at 7:24:44 pm

If you view the property using the graph display, you should immediately see what the issue is. What you think are plain old linear keyframes are actually bezier and have handles for ease-in and ease-out that have been adjusted.

If you select the keyframes and right click on them, you will get a menu in which you can choose "keyframe interpolation", or something like that. Then make sure all the properties are set to linear. Now when you look at the graph you should see straight lines only!

And the Lord said, "Come forth and receive eternal life." But I came fifth and all I got was a set of steak knives!


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Evan Thompson
Re: Corrupt Keyframes
on Apr 21, 2013 at 10:00:34 pm

Joseph,
Thank you for your reply.
Yes, they are Bezier, because they are "eased". But the "ease" has nothing to do with it. Even if I do switch them to Linear, the same issue is still present. It is acting like there is a keyframe in between them changing their value.

Chris,
I had not known what the graph was for before. Thanks for bringing it up. I looked at the graph, and it didn't matter whether it was Linear or Bezier, the lines on the graph changed, but the effect did not.
I have been using the keyframe interpolation menu to change the keyframes from "eased" back to regular linear keyframes.

Update:
I just checked into the keyframes interpolation menu a little more. Changing the Spatial Interpolation to Linear as well did the trick. It doesn't do this to all the keyframes I switch over, but for some reason it does happen to some.

Thanks for the link by the way, it's always good to get more knowledge about this kind of stuff. (If I had watched it earlier, it might have given me a clue to the problem.)

Now I have control over this issue.
Thank you for your assistance.
-Evan


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Todd Kopriva
Re: Corrupt Keyframes
on Apr 21, 2013 at 10:24:51 pm

more information here:
After Effects Help section on spatial interpolation

---------------------------------------------------------------------------------------------------------
Todd Kopriva, Adobe Systems Incorporated
After Effects quality engineering
After Effects team blog
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Evan Thompson
Re: Corrupt Keyframes
on Apr 21, 2013 at 10:54:39 pm

Thanks for the extra information Todd.

That page actually contained a direct answer to my original question!

"In some cases, the Auto Bezier spatial interpolation for Position keyframes can cause undesired back-and-forth (boomerang) motion between two keyframes with equal values. In such a case, you can change the earlier keyframe to use Hold interpolation or change both keyframes to use Linear interpolation"


This all clears up this issue for me.
Thank you very much CreativeCOW and members!
-Evan


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Joseph W. Bourke
Re: Corrupt Keyframes
on Apr 21, 2013 at 10:49:54 pm

Evan -

Another thing you might check - and this one has caught me many times - is to zoom way in on your comp and make sure there aren't any "extra" keyframes within a frame or so of the originals. These are sometimes covered when you're zoomed out, and can cause all sorts of havoc. But usually the Linear switch will take care of the problems with funky movement.

Joe Bourke
Owner/Creative Director
Bourke Media
http://www.bourkemedia.com


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Evan Thompson
Re: Corrupt Keyframes
on Apr 21, 2013 at 10:59:00 pm

Joseph,
Thanks for the tip. Zooming isn't an issue; I make sure there are no extra keyframes existing. However, if multiple keyframs can be in the exact same frame, then that might catch me off guard.

Can two or more keyframes be in the exact same frame?


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Joseph W. Bourke
Re: Corrupt Keyframes
on Apr 22, 2013 at 12:45:36 am

Not that I'm aware of - the problem I've had in the past was that there was a rogue keyframe about 1 or 2 frames away from my correct keyframe. It was my fault, for changing a parameter when I shouldn't have, but it sometimes happens.

Joe Bourke
Owner/Creative Director
Bourke Media
http://www.bourkemedia.com


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Evan Thompson
Re: Corrupt Keyframes
on Apr 22, 2013 at 11:11:31 am

I don't think they can. But I will be sure not to miss any unwanted keyframes.
Thank you,
-Evan


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Chris Buttacoli
Re: Corrupt Keyframes
on Apr 23, 2013 at 1:01:55 am

The graph can show you temporal or spatial views by the way. You just have to select from the bottom which view you want.

And the Lord said, "Come forth and receive eternal life." But I came fifth and all I got was a set of steak knives!


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Evan Thompson
Re: Corrupt Keyframes
on Apr 23, 2013 at 1:20:46 am

Right, Thanks.


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