Issue with playback and export in FCPX; seems to be related to codecs.

Question

Issue with playback and export in FCPX; seems to be related to codecs.

Hey guys. I have started having issues, as of maybe a couple weeks ago, where H.265 "masters" exported from Resolve cause issues in FCPX. The main two things are

Black flashes appearing during playblack (like frames are being dropped, and FCPX is displaying a black frame in the place of the dropped frame). The flashes increase in frequency when I use the L key to speed up playback, but don't repeatedly appear in the same places. No corresponding audio issues.
Exports fail EVERY time. Sometimes immediately, sometimes a little while into the video. The error dialogs, when they give me a reason, tell me that it couldn't render a certain frame of a certain angle, and the frame is different every time. (When I remove or replace the angle, it tells me a different angle is causing issues.)

I have tried a LOT of fixes, including resetting FCPX preferences, changing SSDs, migrating to a new project, etc. The only thing that has worked is re-exporting from Resolve as ProRes. Weirdly, "optimizing" media in FCPX *doesn't* work; I have to start fresh.

My pipeline is Sony XAVC HS footage, graded in resolve and exported as 4k 10-bit "Main 422" H.265. (I find having lightweight grade footage is super helpful, and imho the footage looks fantastic, almost indistinguishable from ProRes.) I do a lot of multicam stuff. I've been using this pipeline for more than a year with no issues.

I am running Sequoia 15.3.1 on a MacBook Pro 16-inch, M2 Max 64 GB RAM.

Is there a fix for this? Is it a Sequoia thing?

MacBook Pro 16″, macOS 15.3

Posted on Mar 24, 2025 12:57 PM

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Answer 1

Meg The Dog

Level 6

13,645 points

Mar 24, 2025 1:26 PM in response to stuffsmithstuff

How much disk space is available on your system drive?

Questions just for clarity:

stuffsmithstuff wrote:

2. Exports fail EVERY time. Sometimes immediately, sometimes a little while into the video. The error dialogs, when they give me a reason, tell me that it couldn't render a certain frame of a certain angle, and the frame is different every time. (When I remove or replace the angle, it tells me a different angle is causing issues.)

Does this mean you grade the camera file in Resolve, export that corrected file as a H.265 file and import that into FCP to construct a Multicam? How many angles are you working with in the Multicam?

I've been using this pipeline for more than a year with no issues.

Any software/hardware changes or additions that coincide with the problem?

MtD

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Answer 2

terryb

Level 4

2,874 points

Mar 24, 2025 4:52 PM in response to stuffsmithstuff

What happens if you open a previous library that used H.265 exported from Resolve? Are you able to export from FCP? If you don't have access to the older libraries, maybe try importing a Resolve H.265 from before the Sequoia update and see if you can export it. It's possible it's the H.265 export from Resolve that's broken.

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Answer 3

Mar 24, 2025 4:39 PM in response to Meg The Dog

Hey, thank you -

Yes, you have it right in your summary of my pipeline. My last project (the first to have this issue) had five angles plus an audio track. This one has three angles plus an audio track. I generally edit up to about eight angles at a time using this method.

And you know — your question about software changes prompted me to go look in my system panel to see when I updated to Sequoia. The timing of my first issues lined up pretty closely with the update. Is it possible that the update messed up something about the H.265 decoding on a system level? (Otherwise, no software or hardware changes that I can find.)

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Answer 4

Mar 24, 2025 5:13 PM in response to terryb

What happens if you open a previous library that used H.265 exported from Resolve? Are you able to export from FCP? If you don't have access to the older libraries, maybe try importing a Resolve H.265 from before the Sequoia update and see if you can export it. It's possible it's the H.265 export from Resolve that's broken.

GREAT IDEA. I just tested it out and had no issues at all with older H.265 footage exported from Resolve. I bet it's an encoding element from Resolve causing the issue. That narrows down my troubleshooting, at least.

Thanks so much!

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Issue with playback and export in FCPX; seems to be related to codecs.