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converting frame rate in after effects 29.97 to 23.98

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Glen Jenningsconverting frame rate in after effects 29.97 to 23.98
by on May 19, 2010 at 7:24:11 pm

What is the best way to convert 29.97 fps to 23.98 in After Effects that looks good?

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Dave LaRondeRe: converting frame rate in after effects 29.97 to 23.98
by on May 19, 2010 at 9:31:46 pm

Frame rate conversion software like Twixtor or Magic bullet. They're the best.

Open up your wallet: the plugins cost about $500.

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

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Chris WrightRe: converting frame rate in after effects 29.97 to 23.98
by on May 19, 2010 at 9:46:52 pm

I've tried just about every recipe there is and mine is absolutely perfect in smoothness. Try it for free.

if you want smooth 24 fps and not jerky 24fps then try this

29.97 interlaced to 23.976 progressive

use magnum to split cuts first...

1.Put 29.97i video in new 59.94 "start" comp so that timewarp can access both fields.
2. add effect->time->timewarp speed at 60.545403%, filtering extreme,vector detail 20
3. make new "output" comp 99 fps and drop "start" comp inside it with timestretch 60.545403%
4. output "output" comp with separate audio layer from original video at 23.976 fps fields off. add motion shutter blur if desired.

tested and works well.

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Jim ArcoRe: converting frame rate in after effects 29.97 to 23.98
by on May 20, 2010 at 12:51:08 pm


Your technique seems to work quite well.

Can you help me understand the math involved here? If I timewarp 59.94fps by .60545403, I get 99fps. Then if I timestretch the resulting footage by .60545403, I get right back to my 59.94fps original (albeit with differences "invented" by AE during the two conversions) which I can then output to 23.976.

But why 99fps? What is the relationship between 99 and 23.976 that makes this work?

BTW - I am trying to work out the math to use the same technique on an image sequence from some super-8 film at 18fps.


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Kevin CampRe: converting frame rate in after effects 29.97 to 23.98
by on May 20, 2010 at 2:52:56 pm

i don't think there is any relationship between 99fps and 23.976, it's just that 99fps is the highest fps that ae allows, and thus will produce the quite a few interpolated frames to choose from when dropping around 75% of them to create 23.976fps.

ideally you'd like to get the 30i to 120fps (119.88fps to be precise). that's because 120 is the closest common factor between 24 and 30 (23.976x5=119.88, 29.97x4=119.88). since it is quite easy to create good 59.94fps footage from 30i, going to 119.88fps would only require 1 interpolated frame for every frame, which both timewarp and ae's frame blending (pixel motion) do fairly well. then dropping that into a 23.976 comp would show one-out-of-five of those frames, but the movement should be very smooth.

you could get this with ae, if you used chris's technique, but in the start comp set timewarp to 50% (don't for get to double the comp length, enable time remapping and extend the out point of the footage) then render that comp. you should have 59.94fps footage at half speed, so that's the same as 119.88 footage at full speed, right?

now drop that footage into a 23.976fps comp and the movement should be smooth. going from 120 to 24 fps will definitely produce a very tight shutter angle look, if you don't want it to look like saving private ryan (or any jason stratham action film) try enabling frame blending (frame mix), reelsmart motionblur or timewarp's motion blur trick to bring some motion blur back into the footage.

but to get back to your question about getting 30i to 18fps... if you interpret the 30i footage as being truely 30fps (which will be necessary), then the common factor between 30 and 18 is 90 (30x3=90, 18x5=90).

so, try using chris's method: drop your 30i into 60fps comp add timewarp with a speed of 66.666667 [(60/90)*100], then drop that comp into a new 90 fps, time stretch 66.6667 and output at 18fps.

Kevin Camp
Senior Designer

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Zach FineRe: converting frame rate in after effects 29.97 to 23.98
by on Sep 1, 2016 at 12:38:46 pm

Interesting -- does the TimeWarp filter with Pixel Motion not internally deal with interlacing?

I just handled this process in a way that seemed fairly intuitive with some 29.97 stock footage that I needed to use in a 23.976 comp.

  • dropped the 29.97 footage into my 23.976 timeline.
  • set AfterEffects's interpretation settings for the 29.97 footage to conform it at 23.976 (result: no skipped frames in the timeline, but it's running at 80% speed).
  • In the timeline I applied the TimeWarp effect to the footage and set it to play back at 125% speed with 'Vector Detail' 20 and Filtering 'Extreme'.

This looks pretty much perfect as far as I can tell. But I may have gotten lucky in that the stock footage appears to be progressive.

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Chris WrightRe: converting frame rate in after effects 29.97 to 23.98
by on May 20, 2010 at 5:19:00 pm

So you want to take super-8 18 fps and make it more smooth at 24fps, or you want to take 30i and turn it into 18fps? Is the source a telecined 18fps on a minidv tape at 29.97i or a true 18fps image sequence?

And yes, 99 fps is the most that AE lets you create new/fake frames. Then you do a technique called decimating that throws away a lot of spare frames so that you have a constant interval of motion between the small ammount of information in 24fps. This is also used in repairing jerky video or bad pans.

That's why some stuff still looks messed up in some camcorders with 24fps reverse pulldown.

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Jim ArcoRe: converting frame rate in after effects 29.97 to 23.98
by on May 20, 2010 at 11:13:07 pm

Right now, I want to take super-8 18 fps and make it more smooth for a DVD at 24fps. The source was captured a frame at a time and is a tif sequence, so it is truly an 18fps image sequence. (At least I think that S8 is 18fps. This is silent S8 and maybe that was shot at 16fps?)

BTW, I first saw your recipe for 30-->24 a few months ago when searching for a better solution for some other frame-rate conversion I was doing. After spending an hour or two on the math, I just used your recipe, figuring I'd come back to the lesson some other time. When I saw your posting yesterday, I figured it was time and began crunching numbers with no success - it just never occurred to me that 99fps was as high as AE could go.

Sometimes the simplest answer is the best answer.

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Chris WrightRe: converting frame rate in after effects 29.97 to 23.98
by on May 21, 2010 at 3:53:10 am

I made a project file for you that is setup to maximize the smoothness but it will probably have some artifacts. Read below how to remove in exchange for quality of motion.

It's a good idea to never warp lower than 50% or you can start getting artifacts easily. If you need more quality, increase the vector amount. Make sure extreme filter is on too.

Unfortunately, going from a lower fps to a higher fps is actually harder to do because you have to warp 10x more. So you will have to choose between smoothness and artifacts.

You can play around with the global and local modifiers(detects moving blocks and smooths the tweening), the vectors(motion detection threshold) and filter extreme(high quality). The main thing that will determine your quality will be how much you slow down the video. If you warp down to 18%, you'll get the maximum
possible smoothness, but you'll probably get some artifacts.

Simply determine the "start" comp fps and divide by 99 will be the number for timewarp speed and timestretch. I strongly recommend trying out different timewarps higher than 18%, it will make artifacts a lot easier to manage.

I also forgot to mention that you have to precomp the footage so that AE will see all the footage and not truncate the "23.976 output final" comp.

(fyi) the original reason I put the 29.97i into a 59.94 is because timewarp can't see fields, so you have to turn each field into a whole frame that gets warped. It's what the engineers said you have to do for better quality But you don't need to do that for non-interlaced.

ae aep

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John ShiskoRe: converting frame rate in after effects 29.97 to 23.98
by on Apr 3, 2012 at 2:39:29 pm

OK, this is a real head-scratcher for me. I am trying to take some 18fps super 8 film and put it on a 24p timeline in PP and/or Avid 6 for editing. I have looked at a lot of solutions online, this seems to be the best as you get clean, discreet frames at 24 fps, but I am not a mathematician and can't really get my head around the math.
-the footage was scanned frame by frame (no pulldown) at 24fps at a professional transfer house, but was shot at 18 fps, so it plays back fast on a 24 p timeline.
-I want this footage shot at 18 fps to play back in "real" speed on a 24 p timeline as there is no native 18fps timeline in Avid or PP, but have a natural discreet frame progressive feel.
I have tried:
1-interpret the 24fps footage to 18fps, but this adds duplicate frames every third frame; not natural film movement
2-tried frame blending in AE on output (softens the image too much, adds movement artifacts) and
3-many flavours of pulldown (this leaves un-natural field artifacts)

And using the suggestions above and getting closer to a solution but not quite there;
-assuming that the common factor for 18fps>24fps is 72 fps (18x4=72, 24x3=72. Also, understanding that the percentage speed up of 18>24 is 33.333%.) I am not sure how the 99fps in AE suggestions work here. I am going on the assumption that, as the common factor is 72fps, there is not need to go to the maximum 99fps in AE, but I could be wrong here.
I have tried:
-doing a 66.67 (33.3%) timewarp on a 24p timeline
-adding this comp to a 72fps timeline
-then outputting this comp to 24 fps

The result: it has the proper progressive discreet frame movement and speed, but has a number of artifacts and is softer than the original. This may be simply par for the course. Generally, it looks pretty good or at least better than any of the other options.

But the part I can't figure, and I did a test of this, is why not ONLY do the 66.67 (33.33%) timewarp on a 24p timeline to bring the 24p footage to 18fps. The results seem to be the same, i.e. the proper movement, but with artifacts. (And yes, I did a bit of experimenting with Vector detail to 50 and Extreme filtering turned on; a lot longer render with about the same results) Why go through the other frame rate conversion steps?? i.e. 24>72>24. I think I am missing something here.

I am not an AE expert by any stretch, but am a pro editor, so this AE thing is a bit new to me. I hope some of it makes sense and any thoughts people have would be appreciated. There seems to be a lot of questions on the 'ole net about how best to get 18>24 and I hope we can figure it.

Also, in the name of simplicity, I have been dealing with true 24fps and not 23.976 fps, but ultimately the calculations should probably be for 23.976 fps I would think.

thanks, John

ps thanks Chris for putting up a sample AE project which I think would have solved all the problems here, but as Megaupload in now shut down, I couldn't get at the file. If you could upload it again somewhere else, that would be grand.

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Chris Wright18 to 23.976
by on Apr 3, 2012 at 10:15:53 pm

I made a much simpler file for AE. It's set for 18-23.976. The timewarp is 50% which is a good trade for warp versus smoothness. You can change the timewarp and timestretch correspondingly so they match up.

The real question is, is 18/23.976 = 0.7507507507507508 a perfect number after you decimate frames? If you can get away with a higher number and still like the smoothness, go for it. There's less chance for artifacts. Don't forget you can create guiding mattes too! there's a draft and high quality timewarp too.

AE CS3 aep 18-23.976


there's twixtor
fcp's compressor

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Gen BickRe: 18 to 23.976
by on Feb 20, 2016 at 11:55:56 am

Hi Chris,

I think I am trying to do the same thing as one of the above posters. I shot super 8 film at 18fps. This has been scanned by a company at 24fps and I now want to slow it down to the original speed. Could you by any chance tell me how I can do this in FCP's Compressor? I'm afraid I found it really hard to understand the AE instructions (and I dont have AE) so is there a really simplified step by step guide? Your method seems to be the best, so I would love to use it if possible. Just doing it by changing the speed in fcp gives terrible results.



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Chris WrightRe: 18 to 23.976
by on Feb 20, 2016 at 3:53:17 pm

here's compressor's method

fcpx incorporates shake's(compressor's) optical flow

if you ever get AE as a trial, try these templates.

if you have any flickering, white balance issues, try my free ae auto whitebalance

whites blown out ae

technicolor (bring back colors) ae

always fix the white point, black, gamma, then white balance first before doing color correction. you can use curves(transfer mode color) to separate the colors at the shoulder. always sharpen after color correction. also, you might need to stabilize the footage if you have gate weave. remove grain if applicable.

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Gen BickRe: 18 to 23.976
by on Feb 20, 2016 at 10:23:03 pm

Thats brilliant, thanks so much! Compressor worked.

I set the duration to 150% of source and this looks about right - hard to get my head around this as I'm used to reducing the percentage in fcp in order to slow it down, not increasing it. Any idea what the correct percentage is for making stuff shot at 18fps but scanned at 24fps play at natural speed? Tried to search online for an answer but I can't find it.

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Chris WrightRe: 18 to 23.976
by on Feb 21, 2016 at 12:00:15 am
Last Edited By Chris Wright on Feb 21, 2016 at 12:17:35 am

its 18/24(75%) so...
it might be 125% which is 100-75=25% slower(backwards of timewarp) like timestretch

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Gen BickRe: 18 to 23.976
by on Feb 21, 2016 at 10:05:09 am

Strangely, the way that I am doing it (possibly wrongly) both of those settings seem to still result in footage that is too fast. 150% seems to be about right, and it looks good so I think I will stick with that. Thanks for all your help.


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Gerry VasbenterRe: converting frame rate in after effects 29.97 to 23.98
by on Mar 25, 2013 at 6:01:20 pm

Hi Chris, I have shot a Promo @33.333 180 shutter, the idea, being able to slip timing on a split-screen,the editor is finding the frame cut to 25 fps is jerky, pre any added motion blur, would your system be worth suggesting as a way of smoothing it out at 25fps?

Best Gerry.

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