Best way to convert 60p footage to 24p without slowing down?

Forum|Forum|8 years ago
May 27, 2017
3 replies
17541 views

Hi all! I've been searching for this for some time with no good answers. Let's say I'm delivering a final video at 24p from a 24p sequence. My project contains some shots filmed at 24p for normal speed playback and some shot at 60p for slowing down to slow motion (either by changing the clip speed on the timeline to 40% and/or by re-interpreting the footage to 23.9760 in the project bin.

But what if I accidentally shot some clips at 60p instead of 24p? What is the highest quality way to have 60p footage shot with a 180 degree shutter play on a 24p timeline and look as close as possible to how it would if I had shot it at 24p with a 180 degree shutter? I know the best answer is to shoot with the frame rate you intend, but let's say I made a mistake.

If I just drop the 60p shots on a 24p timeline it drops frames and the there's too little motion blur, as expected.

if I drop a blur plugin like RSMB, it helps a little, but still looks to be dropping frames oddly

Twixtor is expensive, its frame rate conversion only works in AE, and there are frame interpolation errors, like on frames where a camera flash has gone off. Same thing if I use optical flow and RSMB.

Please help!

This topic has been closed for replies.

dang65882991

Participant

Same boat here. I told a DP about it last week - his laugh memorable. The type of laugh which is not hurtful but "that is truely funny, of all of the problems..." I shot a 90 minute interview in mostly 60p until I discovered my I burned through data so fast. Thanks for posting. Sometimes it takes guts these day to admit what we did and ask for help. We get shellshocked by the "You did it wrong" and about 5% of the people really offer sincere solutions. Anyway - thanks - now off to try these on my footage. - Best - Dan

SlushierCashew

Participant

I toyed with this for a while and finally figured out a reasonable way to get around this problem. Like you, the most common reply I saw to this was of the "the only way is to shoot it properly in the first place" variety; frankly, if you have seen the movies coming out of Hollywood recently you would probably understand that digital technology has advanced to the point where we can do pretty much anything we want these days. Don't know why people read a perfectly reasonable question like yours and troll with these kinds of responses instead of being helpful.

ANYWAY, here's what you do. Open up After Effects, create a new comp with 24 fps as the base frame rate and the other settings however you need them (resolution, etc). Pull in your 60 fps footage, right click and interpret the footage to 24 fps. Drop it into the comp (after setting ins/outs as needed). The footage will be running at 40% speed, as expected. Go ahead and render this out to some sort of lossless or nearly lossless format (that's a fight for a different comment thread). Import this new file into AE (you can delete the original at this point) and add to your comp. Add the "timewarp" effect, change the speed from 50% to 250%, and turn on "motion blur" - make sure the shutter angle is 180 (auto is probably going to do this anyway) and sample is usually 5 (a number you can play with if you feel like experimenting). You will notice your clip is back to original speed, but now takes forever to preview because it is rendering the blur. Render this out to the same format from before, different file (obviously) and use in Premiere as a 24P clip with nice 180 degree shutter blur and cinematic feel. You can also use this motion blur trick to add the proper amount of blur to footage that was shot at a too-high shutter speed (a useful trick for those days when you don't have time to fiddle with neutral density filters).

chrisw44157881

Inspiring

premiere uses same engine as ae for timewarp but you don't have access to motion blur control.

This may sound a little strange, but it doesn't really matter what fps you interpret as or speed up as, as long as the numbers 'reverse' each other. I've found a good number is around 50%, more than that and you get really bad artifacts and less, you get 'jerkyness'.

and you don't have to render it out an intermediate, you can pre-comp in AE and the process will still work.

AE also supports importing any fps into any fps comp, and the comp with optical flow turned on will automatically do the math for the fps conversion so you don't have to interpret fps and do math.

Your way does give you more control than premiere for the size of the motion blur, plus timewarp has matte controls if you get artifacts. its a little more clumsy than twixtor, but not bad for free.

E

excited_Genie16B8

Legend

You can't get the same look without shooting it the same way.

But to play it back, just add it to the sequence. Everything in the sequence will play back at the sequence frame rate.

B

bobd76Author

Participating Frequently

Thanks, Jim. But in this day and age there must be decent ways to convert 60p to 24p. Does anyone have a workflow that's worked well for them? Either optical flow or twixtor plus adding some more motion blur to mimic a 1/48th shutter work okayish. Any other ways?

E

excited_Genie16B8

Legend

there must be decent ways to convert 60p to 24p.

There is. Slow it down.

I don't think it's possible to change the look of a shutter angle after the fact.

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