Artefacts/flicker in exported files

Question

maduro_maio Author

Level 1

8 points

Artefacts/flicker in exported files

Hi, I'm running into a problem that I've tried to troubleshoot in different ways without success.

I have a MacBook Pro 2.9 GHz Dual-Core Intel Core i7, 16 GB 1600 MHz DDR3, HD Graphics 4000 1536 MB, 500 GB SSD.

I'm running Catalina 10.15.7 (upgraded recently) and Final Cut 10.4.10.

I have a project in 4K, 25p, Rec. 709. It has Multicam clips as well as isolated clips on top of the Multicam clips.

There's a flicker/artefact that shows up on and off in the exported files (I exported in 1080), but not on playback in Final Cut.

It appears usually around the center of the image, or center top.

I have deleted render files, and I get the same problem after exporting again. I have enabled/disabled virtually everything...

Every time I change something and render, the artefacts appear at different times.

I inserted a black title and disabled all the clips, and still I can see hints of the artefacts.

I am running out of time and ideas...

MacBook Pro 13″, macOS 10.15

Posted on Oct 4, 2020 4:55 PM

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Answer 1

Tom Wolsky

Level 10

151,179 points

Oct 4, 2020 5:17 PM in response to maduro_maio

Not necessarily. It looks like a compression problem. There data rate in FCP H.264 exports are usually quite high. You might try using the Finder to convert the file to H.265 HEVC and see how the compression holds up.

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Answer 2

maduro_maio Author

Level 1

8 points

Oct 6, 2020 4:38 AM in response to Tom Wolsky

Hi, thanks a lot for the input. Now I know at least the master file is rendered uncorrupted.

However, when I compress it to 1080 I get the same problem, like you suspected.

I'm quite experienced with editing, but very unexperienced with file formats, so a few questions if that's ok:

I wasn't able to find out how to convert the file to H.265 HEVC in Finder, like you mentioned.

And do you mean converting the ProRes file, before compressing it?

Will a more powerful computer be able to compress the ProRes, as they are, into 1080 without these issues?

Thanks so much!

Manuel

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Answer 3

Oct 6, 2020 4:43 AM in response to maduro_maio

A more powerful computer will not help with this issue.

Is the problem always in the same areas if the same frames?

A possible solution is to add a little noise to the image in those areas. That may prevent the compression from introducing those blocky patches.

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Answer 4

maduro_maio Author

Level 1

8 points

Oct 7, 2020 2:48 PM in response to Tom Wolsky

Hi again and thank you two for your help and suggestions.

Turns out that after rendering the ProRes files without any issues, I could actually convert them cleanly to 1080p with Compressor. Actually 1 in 4 tries appeared with artefacts, which maybe had to do with available disk space, or maybe just chance... Good to know my 2012 MacBook Pro still handles this kind of work.

By the way, I tried VideoProc converter (trial version) and was very impressed with its speed and results.

Thanks again!

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