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After Effects interprets 23.976 incorrectly? dropping 3rd decimal?

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Jerome TheliaAfter Effects interprets 23.976 incorrectly? dropping 3rd decimal?
by on Feb 22, 2014 at 6:31:49 pm

It seemed that AE once treated footage frame rates correctly, because I know this worked in the past. Please confirm this by trying to reproduce, it.

Import a frame sequence a few minutes long so there are really differences with very small frame rate changes. Duplicate it so you have 3 instances of it. Interpret one 23.976, the second 23.98 and the third 24. The duration for each clip should go down slightly by a few frames as the frame rate increases.

But what I'm seeing is that AE rounds the 23.976 up to 24. 23.98 is actually closer to what 23.976 should be. And if you try 23.97 (not 23.976) it seems to be closer to what 23.976 should be.

This is very odd and disconcerting and tells me that AE is ignoring the third number after the decimal, the 6 in 23.976. Of course on anything less than a couple of minutes there would be no discernible difference, but on a feature film in which you create 24 and 23.976 versions the sync will be way off by the end of the film.

Anyone else notice this? Is there a work around so that AE interprets 23.976 correctly?

Thanks


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Walter SoykaRe: After Effects interprets 23.976 incorrectly? dropping 3rd decimal?
by on Feb 25, 2014 at 3:28:55 pm

[Jerome Thelia] "Duplicate it so you have 3 instances of it. Interpret one 23.976, the second 23.98 and the third 24. The duration for each clip should go down slightly by a few frames as the frame rate increases."

If you are just looking in the project panel, you'll see the timecode for the 23.976 clip expressed as if it were 24.0 fps.

If you bring all three clips into a comp and compare them on the timeline, though, you'll see that the 23.976 fps interpretation has a slightly longer duration than the 23.98 or 24.0 interpretations.

Walter Soyka
Principal & Designer at Keen Live
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
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Jerome TheliaRe: After Effects interprets 23.976 incorrectly? dropping 3rd decimal?
by on Feb 25, 2014 at 4:59:44 pm

Thanks Walter, you're right and the key thing I missed is that 23.976 triggers AE to automatically move to a 24fps timebase, which is exactly as it should be. So media duration as measured in TC becomes the same in 23.976 and 24fps, but actual duration is different, several minutes different in a 90 minute project. I guess that part of it is relatively new, but a good thing as it eliminates TC variations. thanks

J.T.


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