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Creating a countdown in AE - 29.97 drop frame questions.

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Steve DorseyCreating a countdown in AE - 29.97 drop frame questions.
by on Feb 1, 2010 at 9:40:36 pm

Hello

I'm creating a countdown in AE CS4 that will be one minute long. I have the numbers counting down, and a nifty background made. But this has to be frame accurate and our editors use 29.97 as the standard.

I have a row of "tick marks" which disappear one at a time to count the individual frames. After they all are gone, it starts all over again, once each second.

My countdown is a 30-frame loop but on a 29.97 frame timeline. At about the 523rd second, the countdown and the real frames are out of sync by one frame.

What should I do to fix this? My brain is cramping trying to figure this out.

thanks


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Walter SoykaRe: Creating a countdown in AE - 29.97 drop frame questions.
by on Feb 1, 2010 at 10:01:16 pm

[Steve Dorsey] "My countdown is a 30-frame loop but on a 29.97 frame timeline. At about the 523rd second, the countdown and the real frames are out of sync by one frame."

You're probably seeing the difference between drop frame and non-drop frame time code.

This link explains it pretty well.

Walter Soyka
Principal & Designer at Keen Live
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
RenderBreak Blog - What I'm thinking when my workstation's thinking
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Steve DorseyRe: Creating a countdown in AE - 29.97 drop frame questions.
by on Feb 1, 2010 at 10:05:30 pm

Yes.

I already know what drop frame is. (But that's a great link, thanks for posting! I'll refer it to others who ask). But how would I accurately show a timecode countdown in drop-frame time?

Thanks


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Dave LaRondeRe: Creating a countdown in AE - 29.97 drop frame questions.
by on Feb 1, 2010 at 10:29:35 pm

The time code address where you want to start doesn't even exist. With drop frame, things get sticky at the one-minute mark.

Counting down in SMPTE drop frame time code, the address numbers go from 00:01:00;02 to 00:00:59;29. After that, the numbers count down as they would in non-drop frame. That's how they decided to compensate for the tiny difference between the 29.97 frame rate and actual elapsed time. I could elaborate on the additional compensation that occurs at minutes divisible by 10, but I don't want to fry your brain.

So if you start with 00:01:00;02 and go to 00:00:59;29 on the next frame of the countdown, you will be correct. And there is a 00:00:00;00 time code, too. So you could animate numbers instead of tick marks and stay dead-solid perfect. In fact, I recommend it. Use those tick marks as a design element, and not something to be relied upon for accuracy. Maybe put 93 tick marks around the edge or something and restart them when they're gone.


[Steve Dorsey] "At about the 523rd second, the countdown and the real frames are out of sync by one frame. "

I bet you actually mean the 523rd FRAME. I understand -- this fractional frame rate stuff is just weird, and drop-frame time code is simply an estimation of the actual elapsed time: sometimes it's ahead and sometimes it's behind. It also means that despite your desire to automate things, you may not be totally automatic. Remember that 60*29.97=1798.2 frames... but 60*30=1800 frames. Ugh.


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


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Steve DorseyRe: Creating a countdown in AE - 29.97 drop frame questions.
by on Feb 1, 2010 at 10:33:49 pm

523 - that was a typo.

Thanks for the info - very helpful!

------S



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