FCPX painfully slow and jumpy playback

Hi guys

I'm trying to figure out if there's a way to make FCPX playback better.

I'm on an M1 mac mini with 16GB RAM. Working on a music video with probably twenty clips of various lengths, some masking, some glitchy type plugins from pixel films, and some frame rate plugins. It's a 60fps background shot, so I believe the whole session is working at 60, right?

Playback is very rough and jumpy, to the point where I can hardly tell how the timing is working unless i export the file and playback in QuickTime or something.

Is there any way to give FCPX a break by printing the effects so that it will play back a little smoother? In audio land I'd call this offline printing or rendering a track so the CPU doesn't have to do as much processing on it. I tried creating a couple of new consolidated clips, but that didn't seem to help much.

FWIW, i still can't hear the fans on this M1 even when FCPX is moving so slow! :-D

THanks

Geoff

Mac mini, macOS 14.5

Posted on Sep 5, 2024 11:38 PM

Top-ranking reply

Ian R. Brown

Level 7

22,151 points

Posted on Sep 6, 2024 12:55 AM

Is your SSD nearly full? You need at least 20% free for efficient editing.

Try deleting the preferences by holding down the Option and Command keys as you launch FCP until a window appears. Click the "Delete" button.

Another possibility is a corrupt file in the project.

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38 replies

Sep 10, 2024 10:11 AM in response to geofffromdowney

Seems I was mistaken - exporting a file with the scene removal mask enabled adds a black background. I had to use scene removal mask, and a green background to export, then the green screen keyer as Ian suggested.

Seems like a bit of a silly workaround, but whatever. I'm starting to wonder if the green screen keyer takes some processing power too, as I'm getting some jumpy playback now too - though not nearly as much as before. I suppose I can always disable clips and work on one at a time as a workaround, then enable everything when I want to export the whole project.

Tom Wolsky

Level 10

151,837 points

Sep 10, 2024 11:07 AM in response to Ian R. Brown

HEVC can carry an alpha channel, but I don't seem to have the option to do that from FCP. Compressor can. I think it's because Apple Devices .m4v doesn't support it. In Compressor you can make a QuickTime HEVC preset with alpha.

Sep 7, 2024 10:39 AM in response to geofffromdowney

What are the clips . . . 8K, 4K or 1080p?

Sep 7, 2024 11:08 AM in response to Ian R. Brown

All clips are 1920x1080, 60p

Sep 8, 2024 11:12 AM in response to Ian R. Brown

Glad to hear that 😄 I’d rather keep my current machine!

Sep 8, 2024 11:15 AM in response to Ian R. Brown

Thanks, can do that - but what’s the advantage of adding the green background over just exporting the clips with no background if I’m going to key it out anyway?

Sep 9, 2024 9:21 AM in response to Ian R. Brown

Thanks Ian - yeah scene removal mask leaves a transparent black background.

Thanks for all your help! happy Monday :-)

Sep 10, 2024 11:22 AM in response to Ian R. Brown

Got it, thanks Ian and Tom.

In other news, TIL what an alpha channel is. :-)

FCPX painfully slow and jumpy playback