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Using After Effects to convert 24 fps footage to 29.97
Hey guys,
Someone recently showed me a trick for converting a 23.98 movie in after effects to 29.97. We needed to do this to deliver to a client a bunch of spots that were shot and edited at 23.98, but needed to deliver (tapeless in the form of data files) as 29.97 NTSC D1. All we did was create Comps in After Effects at the spec we wanted (i.e D1 29.97) and the length of the spots (10 sec in this case) and THEN dropped in the 23.98 clips. AE apparently stretches the clip to fit the length of the comp and seems to add some duplicate frames. It looks fine on playback, and definitely looks better than adding pulldown and interlacing the traditional way.
SO…my question is, does anyone know of a reason why we should not do this in the future? Anyone know exactly what AE is doing here to the footage (I am an editor and do not pretend to know everything about AE’s inner workings).
Is this a cool trick or a mistake that is going to catch up with us? Maybe someone has a better idea of how this should be done.
Thoughts would be appreciated.
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5 Replies
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i don’t think there would be any problem with this method if you needed to get 24p up to broadcast rates, unless a client felt the a pulldown created smoother motion. i guess if someone needed to re-edit they might be a little confused by the duplicate frames, but they’d probably figure it out, and the duplicates should be in a regular cadence, so it shouldn’t be hard to remove.
as an alternate method, i believe you could put your footage into a 23.976 comp, but at render set the render settings to use 29.97 for the frame rate rather than the comp’s frame rate (default).
the result should be the same, just another way to work…
Kevin Camp
Designer – KCPQ, KMYQ & KRCW -
uh-oh, me and dave are at odds… there goes our credit roll business plans…. 😉
there may be a potential problem due to the uncommon method of bringing the footage up to broadcast standards, but i’m really not sure.
if you really hate pulldown, maybe you could try working in 30p. if you can shoot 30p, it’s almost the best of both worlds… film-like progressive feel, but at broadcast friendly framerates…
Kevin Camp
Designer – KCPQ, KMYQ & KRCW -
Thanks for the opinions. I know that it is easy to add pulldown in AE on render (although, Dave, your explanation is nice and clear for anyone that has never done it), but we were trying to stay away from adding ugly interlacing to our project files.
moldyboot(?) – as you mention, it would confuse anyone who tried to edit with the files, but in theory no one will do that. They will simply put them on to airmasters etc, they won’t be cutting them at all.
I think I will stick to adding pulldown in the future because it is safer, but I wanted to see what people thought of this method.
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And what are the tricks going the other way around- 29.97 to 23.976? and then uprezing to HD? Should I do the interlaced to progressive first and then separately uprez? Or all at once, together?
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Is there a hardware converter solution for this 29.97 to 23.976 (digibeta to HDCam deck)? and how does the quality measure vs the software solution? Does Terenex do a frame rate conversion? Do you have a post house you could recommend?
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