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After Effects export frame rate issue

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Jason RogersonAfter Effects export frame rate issue
by on May 17, 2015 at 5:33:59 pm

I am using Keylite 1.2 in After Effects to key out green screen shots that I am then bringing into FCP 7 to composite over backgrounds. The keying turned out well, but the problem is when I bring the new Alpha channeled Quicktimes back into FCP and lower the opacity on these shots, I see they are not quite in synch with the original green screen footage on the layer beneath. Seems like a frame rate issue. The original footage is 23.98 fps. When I imported the source footage into AE, the program defaulted to 23.976 fps. I did a new composition of the same footage at 23.98 setting, hoping this would solve the problem, but it didn't. The other curious thing is that when I nudge the newly keyed footage (23.976 fps) to the left in the timeline by 1 frame, it seems to synch up. But I have to trim off the first frame. The bigger issue is that I am losing a frame at the end of the clip, creating a one frame gap before the next shot.

In terms of my AE render export:
To get a good key with no rim or halo around it, I have unchecked Unpremultiply Results. I'm rendering out at Apple Pro Res 4444 (same as source footage), same frame rate as composition (23.98), Channels: RGB + Alpha, Depth: Millions of Colors +, Color: Straight (Unmatted). These settings are giving me a great key, but maybe these settings may be causing the synching issue?

Sorry for such a long post, but I wanted to provide all the detail I could in hopes of finding a solution. Any advice appreciated.

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Todd KoprivaRe: After Effects export frame rate issue
by on May 18, 2015 at 6:38:52 pm

FCP rounds the real 23.976 frame rate to 23.98 for display. Do not be fooled by this into thinking that the frame rate is 23.98 fps.

Todd Kopriva, Adobe Systems Incorporated
After Effects product manager and curmudgeon
After Effects team blog

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Dave LaRondeRe: After Effects export frame rate issue
by on May 18, 2015 at 11:24:47 pm

You know, you could just do the whole shot in AE, both keyed subject and background. If you're worried, just give yourself some trim handles. It'll work.

Dave LaRonde
Promotion Producer
KGAN (CBS) & KFXA (Fox) Cedar Rapids, IA

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