ADOBE AFTER EFFECTS: Forum Expressions Tutorials Creative Cloud

Converting 60p to 24p in After Effects CS5 - do I need to precomp?

COW Forums : Adobe After Effects

<< PREVIOUS   •   FAQ   •   VIEW ALL   •   PRINT   •   NEXT >>
Mike Imam
Converting 60p to 24p in After Effects CS5 - do I need to precomp?
on Nov 19, 2012 at 5:26:10 pm

Hi all,

Did a search for this but I'm afraid the strings on this topic are a bit too technical for me so I'm hoping someone can help explain in layman's terms.

I'm looking to convert some Canon T2i (550D for our European friends) footage shot at 60p (actually 59.94) to 24p (23.976) in After Effects CS5. A few questions (I'll refer to the "p" frame rates for simplicity but assume they are the exact integers listed above):

- Should I set my main comp at 24p, then import my 60p footage, precomp it in a 60p comp, drag onto my 24p timeline, and adjust the clip on my timeline to 24p via Time Stretch at 160%? This seems to be the best method right now but not sure if there's a cleaner way to do it.

- The above method appears to be identical to dropping my 60p clip directly on to my my main 24p timeline and using Time Stretch to 160%. Any difference? Any advantage to precomping?

- When I tried "Interpret footage" of my original 60p clip and reduced it to 24p (then droppped into a 24p timeline), I got this very strange and unwanted lag every second or so. That is to say, the image freezes for a few frames as it appears the interpolation was not uniform, so this is not the route I'd like to take.

- I looked up Dave's Stock Answer #1 regarding file conversion but I apologize, it was a bit over my head. Is there any reason I would not want to drop my T2i files directly into CS5 and edit them as is? I can easily convert them in FCP but I only want to put the time and HD space in if it makes a tangible difference. Could someone explain why I would want to convert these from H.264, since AECS5 seems to handle them fine?

Any advice would be appreciated on how to do this cleanly and get a proper 24p look (doing some slo mo scenes).

Side note: when I play back the 60p files in VLC and set playback speed to 13x slower, the footage looks silky smooth, and it appears to be running even slower than 160% Time Stretch in AECS5. Any idea why? If VLC can do it I must be able to replicate this look in AE, no?

Thanks!


Return to posts index

Dave LaRonde
Re: Converting 60p to 24p in After Effects CS5 - do I need to precomp?
on Nov 19, 2012 at 5:35:16 pm

This is about as easy as it gets: make a 23.976 comp, put your 59.94 footage into it and you're all set. You can also drag the footage onto the make comp icon at the bottom of the project window, then change the frame rate of the resulting comp to 59.94.

Because of the way the frames fall, AE automatically does the 3 frame / 2-frame conversion so the motion will look right.

That admonition against long-gop codecs was for AE 9 & earlier versions. They couldn't deal with long-gop.

Your big problem: a good delivery codec, and you didn't say anything about what you need to deliver. I wouldn't use H.264 because it's lossy.

Come to think of it, there aren't other details of the project in the post, so all I can comment on is the frame rate conversion.

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


Return to posts index

Mike Imam
Re: Converting 60p to 24p in After Effects CS5 - do I need to precomp?
on Nov 19, 2012 at 5:46:44 pm

Thanks for the quick reply Dave. So be clear, after I drag my 59.94 clips onto my 23.976 timeline I should be ok using Time Stretch to 160%? The goal is to get the clips to play smoothly in slow motion (like they do in VLC reduced to 13x slower). The problem with the method described is that I'm still getting a slightly juddery result (the motion looks jerky rather than smooth). The scene is question is a tracking shot of a man walking down a hallway - the camera follows him from the side.

The end goal of the vid is digital (YouTube, Vimeo and the like) so I think I'll be ok with H.264 (unless there's a noted performance difference using ProRes). I usually just output my clips to ProRes as a master file and then compress them to a hi-res H.264 using Quicktime Pro before uploading to the sites.

Thanks
Mike


Return to posts index


Dave LaRonde
Re: Converting 60p to 24p in After Effects CS5 - do I need to precomp?
on Nov 19, 2012 at 7:03:09 pm

[Mike Imam] "The goal is to get the clips to play smoothly in slow motion (like they do in VLC reduced to 13x slower). "

You should have stated that from the get-go.

You should CONFORM your footage to 23.976 in the Interpret Footage Settings, then put it into a 23.976 comp. The motion will automatically be 2.5 times slower with no loss of image quality.

If you want to preserve maximum image quality, you'll need to get a third-party plugin like Twixtor to slow it down more.

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


Return to posts index

Mike Imam
Re: Converting 60p to 24p in After Effects CS5 - do I need to precomp?
on Nov 19, 2012 at 8:26:50 pm

Apologies, I had added that slo-mo info to my first post but not in an obvious manner.

Thanks for the help! Looks like your suggestion is working to some degree, but it's still a stutter-y for some reason. It appears the thing that has made the biggest difference for me is turning on Frame Blending for the layer. For some reason it's smoothing everything without any ghosting effects (since the frame information exists so it's minimizing interpolation, I assume).

The second thing I did is actually put my 59.94 footage into a 29.976 timeline, and those extra frames have made things look a lot better.

Would love to know the logic behind frame blending as I'm not exactly sure why it helped (again, no ghosting and the frame info exists, so by all accounts the motion should not require blending).


Return to posts index

Dave LaRonde
Re: Converting 60p to 24p in After Effects CS5 - do I need to precomp?
on Nov 19, 2012 at 8:38:33 pm

[Mike Imam] " it's still a stutter-y for some reason."

24p isn't the world's smoothest frame rate, you know. But film school grads like it. It could also be that your computer isn't up to the task of realtime full-resolution previews. Or you could be using the space bar to preview, which is wrong, wrong, wrong. Hit zero on the numeric keypad.


[Mike Imam] "...actually put my 59.94 footage into a 29.976 timeline, and those extra frames have made things look a lot better. "

It shouldn't make any difference at all. I'd like to know how that's happening.

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


Return to posts index


Mike Imam
Re: Converting 60p to 24p in After Effects CS5 - do I need to precomp?
on Nov 19, 2012 at 8:49:09 pm

It is indeed strange, which is why I'm also scratching my head.

As for playback, I'm viewing the results by exporting the clip in ProRes and watching in QT. My ram previews are useful but due to the precise nature of what I'm trying to view I figure outputting was the best method so I could see a true final result.

Hopefully someone out there can explain why the 29.976 timeline options is stunning stutter-free. All I know is it's working...

Mike


Return to posts index

Evan Aspinwall
Re: Converting 60p to 24p in After Effects CS5 - do I need to precomp?
on Nov 8, 2013 at 4:08:28 pm

Does anyone know the percentage of how slow the footage becomes?


Return to posts index

Dave LaRonde
Re: Converting 60p to 24p in After Effects CS5 - do I need to precomp?
on Nov 8, 2013 at 7:49:01 pm

If you put 59.94 footage in a 23,976 comp, the footage doesn't slow down.

If you CONFRORM the frame rate -- change the frame rate from 59.94 to 23.976 -- the footage is 2.5 timesw slower. It's all arithmetic.

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


Return to posts index


Evan Aspinwall
Re: Converting 60p to 24p in After Effects CS5 - do I need to precomp?
on Nov 8, 2013 at 9:02:06 pm

Thanks...yes you are right. I go into after effects and take 60p footage and interpret the footage to 24 p and it slows it down...so if its 2.5 times slower what would be as a percentage...like 60% slower for example?


Return to posts index

Dave LaRonde
Re: Converting 60p to 24p in After Effects CS5 - do I need to precomp?
on Nov 9, 2013 at 1:33:41 am

I don't know. You could drag out the calculator and do the arithmetic instead of me, I suppose......

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


Return to posts index

<< PREVIOUS   •   VIEW ALL   •   PRINT   •   NEXT >>
© 2017 CreativeCOW.net All Rights Reserved
[TOP]