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After Effects moving footage that has been time-reversed.

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Tim Kocher
After Effects moving footage that has been time-reversed.
on Oct 9, 2013 at 7:30:22 pm

I'm not sure why this is happening or how to fix it at this point, but I have a footage layer and am making it "ping-pong" back and forth by creating a duplicate, then time-reversing the duplicated layer. (As I have done many times before.) This is in CS5.5.

However, upon ram preview, when playback gets to the time-reversed layer, the footage shifts up ever-so-slightly. I have tried compensating by moving the TR footage down by one pixel, but that results in it moving down! Yikes.

I have done this hundreds (if not thousands) of times before. It has been a little while ... might have been CS4 last time I did it. Something broken in CS5.5 perhaps?

Any ideas what is happening?


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Todd Kopriva
Re: After Effects moving footage that has been time-reversed.
on Oct 9, 2013 at 8:09:33 pm

Is it happening by only one vertical pixel? Is the footage interlaced? If so, have you separated fields for the footage?

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Todd Kopriva, Adobe Systems Incorporated
After Effects quality engineering
After Effects team blog
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Dave LaRonde
Re: After Effects moving footage that has been time-reversed.
on Oct 9, 2013 at 9:25:58 pm

If Todd's interlacing suggestion isn't relevant, you could do it all in a single layer with Time Remapping keyframes: no multiple layers to hassle with.

Dave LaRonde
Former Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Tim Kocher
Re: After Effects moving footage that has been time-reversed.
on Oct 9, 2013 at 10:00:58 pm

Thanks for the responses, guys. Todd, no this is 1080p footage ... good thinking though. Dave, true ... haven't done that before (time-reverse has always worked), but I'll give it a shot.

Maybe it is just an optical illusion (it does deal with an item rotating), but I kind of doubt it. Maybe I'll try it with some other unrelated footage and see what happens.

-Tim


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Tim Kocher
Re: After Effects moving footage that has been time-reversed.
on Oct 11, 2013 at 2:46:27 pm

Eureka!! And thank you, Todd! The problem was interlaced-related, but not in the way you think ... exactly. What happened is, when I tried the time-remapping method (which is much more elegant/straight-forward, so thank you Dave!) it was bouncing not just at the reverse, but the entire playback.

Sooo, besides "what in the world", I started thinking this has to be an interlacing issue of some sort, as Todd said. Sure enough, the footage was being interpreted as INTERLACED, when in actuality it is just recorded in an interlaced stream, but is actually progressive. Shot with an XA10, Canon calls it (as do others I think) PF30.

I have run into this before and could have sworn I fixed AE's interpretation, so I don't know if I forgot, or did it and hit cancel or what, but that is definitely the issue. I never understood why they had to record (and still do with the XA20/25 in AVCHD mode anyway) to an interlaced stream.

Anyway, thanks to both of you once again!


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