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true 24p to 23.98 conform

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Anhtu Vutrue 24p to 23.98 conform
by on Oct 20, 2012 at 5:11:35 am

I'm getting files (DPX sequence) extracted from DCP in 2048 x 858, true 24p and discrete 5.1 surround. I need to downnres and conform these to 1920 x 1080, 23.976. What's the best approach via AE cs6 ??

would this work ?

1- Import DPX sequence in AE and make sure ''interpret footage'' sees it as 24p (for some reasons the few tests i did, AE sees these DPX sequence as 30, i had to change it manually)

2- now this is the part i'm that i'm unsure, do i simply drop this DPX sequence on a comp with resolution set to 1920 x 1080 and frame rate set to 23.976 ??? How about pull up / down settings ???

As for the audio, i will do it seperately in Protools as all these video apps simply mess up the audio.

Thanks



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Dave LaRondeRe: true 24p to 23.98 conform
by on Oct 20, 2012 at 5:39:38 am

You're going to have audio problems if you change the frame rate: the sound will slowly drift out of sync.

After Effects defaults to importing image sequences to 30 frames/sec. It can be changed in AE preferences, I believe.

Here's the proper method you want: Import the sequence. In the interpret footage settings, change the sequence's frame rate to 23.976. Put the footage in a 1920x1080 23.976 comp.

Because you changed the frame rate, the comp will now be slightly linger than than the original 24fps footage. You'll have to talk to your audio people about changing the duration of the 5.1 surround audio.

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


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Anhtu VuRe: true 24p to 23.98 conform
by on Oct 21, 2012 at 6:38:26 pm

@Dave

I'm not sure if you've read my entire thread as i'm aware of the audio problem and mentiomned that i will conform in Protools. All these video apps (After Effects, Cinema tools, Premiere, FCP....) can't properly conform audio.

Anyways, regarding your suggestion, why would you want to interpret the DPX sequence as 23.976 since it is true 24. Isn't the proper way is to interpret as 24p then drop it in a 23.976 comp ??? thx



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Dave LaRondeRe: true 24p to 23.98 conform
by on Oct 21, 2012 at 7:41:55 pm

Sorry, I missed the ProTools part.


You have to get to 23.976 eventually, so you may as do it the very best way you can, right from the start. That would be to interpret the sequence as 23.976. You gain absolutely nothing by interpreting as 24 and placing it in a 23.976 comp.

Wait, that's wrong, you DO gain something: you gain erratic motion problems in the final render due to the frame rate mismatch.

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


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Anhtu VuRe: true 24p to 23.98 conform
by on Oct 21, 2012 at 9:46:39 pm

Thanks Dave....I have a few more questions:

1- So what you're saying is AE conforms differently when you do it in the interpretation stage or comp stage or render stage ???

2- I tried your way by interpreting a true 24p clip as 23.976 then put it in a 23.276 comp then render out as 23.976

or

Interpret as original 24p, put it in a 24 p comp then render out as 23.976..

End result looked exactly the same!



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Dave LaRondeRe: true 24p to 23.98 conform
by on Oct 22, 2012 at 5:27:49 pm

[Anhtu Vu] " AE conforms differently when you do it in the interpretation stage or comp stage or render stage ??? "

The ONLY time AE conforms is in the Interpret footage stage. That's why you do it then.

[Anhtu Vu] "...or... Interpret as original 24p, put it in a 24 p comp then render out as 23.976.."

Once the comp is in the Render Queue, AE won't change its frame rate. Try it and see. This is why you interpret as 23.976 and render in a 23.976 comp.

Don't fight City Hall on this one. You may think AE should work differently, but it doesn't. Go with the flow and have a much better AE experience.

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


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Anhtu VuRe: true 24p to 23.98 conform
by on Oct 22, 2012 at 11:57:08 pm

once the comp is in the queue, there's a box where you can change the frame rate..and that's where i changed it to 23.976 and as i said the end result looked the same as if i was to change the frame rate at the interpret stage as suggested.



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Walter SoykaRe: true 24p to 23.98 conform
by on Oct 23, 2012 at 5:05:48 am

A similar issue was covered recently in another thread about 24.0 vs 23.976 fps [link].



[Anhtu Vu] "once the comp is in the queue, there's a box where you can change the frame rate..and that's where i changed it to 23.976 and as i said the end result looked the same as if i was to change the frame rate at the interpret stage as suggested."

This is not the right way to do it. Consider what's happening -- you have a source footage item that has 24.0 frames every second, and you are sampling it at 23.976 frames per second for render. You are not changing the duration, which means you have to squeeze 24000 frames on the source side (over 1000 seconds) into 23796 frames on the output side. To do this, you must skip 24 frames every 24,000, or one frame per thousand.

By interpreting the footage at 23.976 fps, you preserve all your original frames, but alter the total duration slightly.

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
Creative Cow Forum Host: Live & Stage Events


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Dave LaRondeRe: true 24p to 23.98 conform
by on Oct 23, 2012 at 2:57:35 pm

As the other posters have alluded to, that is simply not the proper procedure. If you're unwilling to follow my advice, please follow theirs.

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


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Vishesh AroraRe: true 24p to 23.98 conform
by on Oct 20, 2012 at 9:45:31 am

Anhtu

Go to Edit> Preferences > Import and change the default Sequences Footage Frame Rate as required.

Vishesh Arora
3D and Motion Graphics Artist
Films Rajendra

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