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24p to 23.98 conversion issue/major problem: audio drift/rate conform question

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Christopher Morrison
24p to 23.98 conversion issue/major problem: audio drift/rate conform question
on Aug 26, 2018 at 7:48:36 am

There must be an easier way to do this. I've banged my head for a week and a half and have come up with a solution. But, MAN, it sucks.

Background: I have a feature I'm doing my deliverables for. We did everything at 24p, the distributor wants the print master in 23.98.
So I have to deliver: the visuals and 16 lines of audio (our Stereo, M&E, 5.1 stereo, 5.1 M&E) at 23.98...
right now all separate files at 24p.

I can, obviously, put them all in a 23.98 timeline, but when I rate conform (and render) it using optical flow (or any option) I get audio drift from hell.
I tried conforming the visual in FCPX and then conforming the audio in Pro Tools... massive drift as well.

Question: I can't seem to find a way to rate conform BOTH the visual and the audio at the same time in FCPX without having to export the film at 24p with ONE line of audio (b/c if I do a multi-track .mov file FCPX will separate the audio back into separate lines); re-import that .mov file to a 23.98 project; rate conform and render the joined visual and audio; then export only the audio to have an audio track that will conform to my 23.98 visual
(which I will keep based off the 16th render of the visual/audio); assemble the Print Master based on the 16th project.
Here's the simplified questions:
1. Is there no bloody way that FCPX can rate conform a compound clip WITH the audio attached? (would save a few steps in the above stupid process.)
2. Will FCPX rate conform the visual the exact same way if I do have to do this 16 times? And will each conformed audio line match the visuals once exported to separate files?
3. PLEASE GOD TELL ME THERE'S AN EASIER WAY. Someone must have dealt with this before.

Thanks for your time... and sorry for all the capitals I'm frustrated beyond belief here.

Cheers.

Working on: MacBook pro 13 inch early 2015
High Sierra 10.13.2
FCPX: 10.4.3


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Jeremy Garchow
Re: 24p to 23.98 conversion issue/major problem: audio drift/rate conform question
on Aug 27, 2018 at 1:30:16 am

Do you have the audio stems separately?

If not, no matter.

Run the video through compressor keeping the length at 100% and change the frame rate to 23.976.

Import the video, lay in the audio from the original file and that should do it.

Another method would be to run the original file 24@23.98 (meaning a frame to frame conversion), but that will slow down the entire movie and then you’d have to remix the audio to this new timing. This option is obviously not ideal.


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Christopher Morrison
Re: 24p to 23.98 conversion issue/major problem: audio drift/rate conform question
on Aug 27, 2018 at 7:47:50 am

Sorry n00b to Compressor.

When you say "keeping the length to 100%" is that a setting (if so, I'm having trouble finding it). Or do you just mean to not alter the length in the Compressor timeline/window display?

And since I'm here, yes, I have all the audio stems as separate files.

Also, just for fun and if I can't make the first option work, did not follow the second option: "running a frame to frame conversion".

Thank you very much for your time and response and sorry for the n00bness. :)


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Jeremy Garchow
Re: 24p to 23.98 conversion issue/major problem: audio drift/rate conform question
on Aug 27, 2018 at 1:12:29 pm

[Christopher Morrison] "When you say "keeping the length to 100%" is that a setting (if so, I'm having trouble finding it). Or do you just mean to not alter the length in the Compressor timeline/window display? "

Yes. It's a setting. Click the 'General' tab in the inspector and check out the retiming section. See here:





[Christopher Morrison] "Also, just for fun and if I can't make the first option work, did not follow the second option: "running a frame to frame conversion".
"


The other option to take the 24.0 fps and "rewrite" the at 23.976 fps. This will literally retime the movie and make it longer (thus screwing up the sync, which is essentially you are doing in FCPX by retiming the 24 to 23.98). This is also done in the retiming section here:





What you want is to keep the movie at the length it is now, set the frame rate to 23.976, and keep audio sync.


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Andreas Kiel
Re: 24p to 23.98 conversion issue/major problem: audio drift/rate conform question
on Aug 27, 2018 at 4:59:21 pm

Jeremy is right.

If you have a 48 kHz audio matching a 24 fps video the obviously has 48.000 samples per second.
If you slow down the video to 23.976 the audio want match - change the rate to 47.952 samples per second and everything will be fine. But if you need 48.000 Hz the file must be re-sampled.

Spherico
http://www.spherico.com/filmtools

"He who fights with monsters should be careful lest he thereby
become a monster. And if thou gaze long into an abyss, the abyss will
also gaze into thee." - Friedrich Nietzsche, Beyond Good and Evil


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Christopher Morrison
Re: 24p to 23.98 conversion issue/major problem: audio drift/rate conform question
on Aug 27, 2018 at 5:42:37 pm

Duh. It is an option on the "general" panel... It was under the "video" panel.

It works. Thank god.

BUT. of course.

I'm getting an insane amount of "ghosting" in the image on occasion (see attached).
I've set the resize and the retiming filters both to "best".

Anyone got any ideas how to fix this issue?

Thanks.



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Jeremy Garchow
Re: 24p to 23.98 conversion issue/major problem: audio drift/rate conform question
on Aug 27, 2018 at 6:14:19 pm

Change it from Best to Fast.


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Christopher Morrison
Re: 24p to 23.98 conversion issue/major problem: audio drift/rate conform question
on Aug 27, 2018 at 6:22:10 pm

Wait. That seems counter-intuitive.
It's certainly worth a try... but also... which one? The resize filter? Or the Retiming? Or both?


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Jeremy Garchow
Re: 24p to 23.98 conversion issue/major problem: audio drift/rate conform question
on Aug 27, 2018 at 6:25:57 pm

Retiming only, unless you are changing the size?


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Christopher Morrison
Re: 24p to 23.98 conversion issue/major problem: audio drift/rate conform question
on Aug 27, 2018 at 6:29:51 pm

Not changing the size but the pull down is active and it seems like you have to make a choice.
I'll leave it at "Nearest Pixel" (the default option).

Thanks! I'll let you know!


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Jeremy Garchow
Re: 24p to 23.98 conversion issue/major problem: audio drift/rate conform question
on Aug 27, 2018 at 6:30:44 pm

[Christopher Morrison] "Not changing the size but the pull down is active and it seems like you have to make a choice. "

Yes just leave it as Linear (Fastest).


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Christopher Morrison
Re: 24p to 23.98 conversion issue/major problem: audio drift/rate conform question
on Aug 28, 2018 at 9:03:24 am

Well, holy heck. That did the trick.

MANY thanks to Jeremy Garchow!! You are my hero.

The final trick laid out here:
Send to Compressor
Retiming (under the General tab) set to 100%
Frame Rate (under Video tab... as the rest are) set to 23.976
Resize Filter at default
Retiming Quality set to Fast (Nearest Frame)
Compress away...
Lay the video file into a 23.98 FCPX Project
Lay in the audio and VIOLA! No audio drift, no ghosts.

Onward!


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