Final Cut Pro 4K H.264 Export Videos Pixelated During Dynamic Action Shots

Currently running:


Mac Studio with Apple M1 Max and 64 GB RAM

Final Cut Pro 10.6.5

Ventura 13.3.1 (a)


Noticing that some 4K exports directly from Final Cut Pro have pixelation at times.

Most pronounced in darker footage, foggy footage, and higher dynamic action shots.



If I export as 720p it's fine, crisp detail. Same for Apple ProRes 422, it's crisp detail.


A workaround is to export the ProRes 422 version from Final Cut Pro, then use Compressor 4.6.3 to convert that ProRes 422 to 4K H.264. Compressor's output will NOT be pixelated, AND the file size is actually reduced!


So there are two problems with Final Cut Pro's 4K H.264 export:

  1. it has pixelation issues during high dynamics
  2. and it's not optimizing file size


Please fix!


Mac Studio (2022)

Posted on May 8, 2023 7:38 PM

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May 9, 2023 1:15 PM in response to Luis Sequeira1

Hello Luis,


Thx for your reply!


Tried cutting out some problem samples for you to try and re-rendered those samples this morning, but no pixelation. Tried creating a new project and putting the whole raw video in there, renders OK. Tried rendering edited project again, pixelates. Tried copying edited project to new project, has pixelation.


It's interesting, the only real edit in this project is a colour curve to bump up luma when the performer walks around in the dark, then the luma bump ends, right after that is when the pixelation happens.


Not sure what to think at this point.. pixelation only happens on 4K H.264 export, but no pixelation on this project when exporting at 720p H.264 or ProRes 422. That ProRes 422 export can then be run through Compressor to make the 4K H.264 that my customer needs, and it's fine. So that will be my workaround for now.


I've got to get back to work on my customer's project now, but if I can find a way to consistently replicate this I will post an update.


It's worth noting that the two mini-films I experienced this pixelation glitch on both had performers walking around in the dark, where I used the colour curve and keyframes to bump the luma so you could see them in the dark, then after the luma bump ends, shortly thereafter the pixelation event happens, but only on 4K H.264 export.


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May 11, 2023 2:36 PM in response to openheartmonk

Update:


While I have not yet found a consistent way (with shorter clips to share with you) to replicate the pixelation issue on 4K export, I have definitely replicated an issue with generated file sizes:



Here we have the very same video, exported various ways:


-4K export direct is directly exported as 4K H.264 from FCP, is pixelated at times, with 2.75 GB file size.


-4K via compressor destination was exported from FCP via Compressor Settings (4K H.264) destination. This one took a very long time to export, and generated a 1.72 GB file size, with no pixelation.


-ProRes-4K is a Compressor generated 4K H.264 output that was fed a ProRes input, again comes in with a 1.72 GB file size. No pixelation.


-ProRes is a ProRes export from FCP, no pixelation. Fed this into Compressor to make the non-pixelated 1.72 GB 4K H.264.


-HD 720p and -Small we can ignore for this discussion, they were smaller formats generated for my customer using Compressor, and of course, no pixelation.


So I really want to drive home this point -- there is an issue with the FCP 4K H.264 export.. why is the file size more than 1 GB larger for the very same video file?


..I'll keep working to replicate a smaller video sample that reliably demonstrates the pixelation issue and post here when I have it for you. I suspect it has something to do with blading clips.

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May 9, 2023 1:42 PM in response to Tom Wolsky

Hello Tom,


Thanks for your reply!


Having difficulty replicating the issue with short sample clips, but doing another pile of edits today so if something shows up that I can share I will post an update here.


One detail about this glitch happening after a colour curve luma bump.. I did use the blade tool to cut the dark part of the clip and only applied the colour curve to the trimmed section. Wondering if coming off the bladed clip is what triggers the 4K H.264 to glitch into pixelization? If I can make it happen again on a short clip I'll provide a sample.

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May 11, 2023 2:53 PM in response to openheartmonk

FCP master file export to H.264 uses a high data rate, probably higher than it should, but that’s not relevant to the the pixelization problem. We need to see if we’re can reproduce the very pronounced problem you’re seeing. If you could upload a file you have to WeTransfer or to your Dropbox we might be able to see what’s going on.

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May 11, 2023 3:14 PM in response to Tom Wolsky

Ok, I have been trying to make a smaller segment that replicates this.

The problem is that the shorter I make it, the less the pixelization appears.

Also, if I render the original raw video file, without any edits, it's fine.

If this is an editing sequence issue, what file exactly would you want to see in that case?

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May 11, 2023 3:36 PM in response to openheartmonk

Update:


I think this pixelization issue might be linked to a third party transition plugin I was using on this project.


It's an FxFactoryPro transition called "Whoosh"


When I take the 0.5s Whoosh transition off the beginning of the video clip sequence, the pixelization is greatly reduced. I'll keep playing with this, but since I think a third party software/plugin is now involved, I can't blame FCP directly at this time.


Thx for all your troubleshooting help.. it's still strange that a FCP ProRes 422 export and Compressor 4K H.264 are fine with the Whoosh transition embedded, but whatever. I have a workaround for now.. and yet another reason to be glad I acquired Compressor since it makes cleaner, SMALLER files!

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Final Cut Pro 4K H.264 Export Videos Pixelated During Dynamic Action Shots

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