Final Cut Pro 12.3 Better Optical Flow fails silently on Intel Macs

Hi,

If Better (Optical Flow) is not working as expected in Final Cut Pro 12.3 on an Intel Mac, I suggest checking the following:

Verify that your Mac meets the requirements for your installed Final Cut Pro version.

Back up your Final Cut Pro library before troubleshooting.

Test the problem using a short clip in a new project.

Apply slow motion, then choose Retime > Video Quality > Better (Optical Flow).

Allow sufficient time for analysis and rendering.

Try Good (Frame Blending) to determine whether the problem is specific to Optical Flow.

Please note that Best (Machine Learning) requires Apple silicon, but Better (Optical Flow) is a separate option.

Could you share your Intel Mac model, macOS version, video format, and frame rate?

Also, does rendering complete without changing the output, or does the process fail to start?

Did you render that clip on the timeline? Optical Flow does an analysis, not a full render.

Hi(Bonjour),

Same problem for me with following configuration:

iMac 5K 2020 intel 3.6 Ghz i9 64 Go 2667 MHz DDR4

1To internal SSD with 300 Go free

AMD Radeon Pro 5700 XT 16 Go

Mac OS Sequoia 15.8.2 (24H232)

Final Cut Pro 12.3

Footage on external SSD Thunderbolt Samsung X5, from Sony HXR-NX800 at various formats:

1) HEVC, linear PCM 3840X2160 23.98p

2) H.264 linear PCM 3840X2160 23.98p

3) H.264 linear PCM 1920 X1080 29.97p

Timelines set to 4k or HD @ 23.98 and 29.97

Speed reduced to 50% or 25% with optical flow, analyzed and rendered.

Result: Choppy playback as if I used no flow at all.

Bonus: As Apple dropped Firewire capture with Tahoe (I need it for my workflow with others camcorders) and as FCP 12.4 needs Tahoe (it should be same thing for a possible 12.4.X Patch), FCP 12.3 definitely killed optical flow for me.

Michel B.

Even when the Optical Flow analysis is done, the clip is not rendered, the render dots in the timeline will remain. Optical Flow is an analysis, not a render, very different things. And depending on how much your slowing things down, and what the format of your original footage is, yes, and Intel Mac could have issues playing it back (we have one last Intel Mac left, it does this). But your problem is your system drive is over filled.

30 GB of free space is only enough for a 200 GB drive. So yes, your system drive is over filled and struggling. At least 15% of its total capacity should be free space. A 1 TB drive must have at least 100 GB or more left as free space to operate smoothly.

Delete all render files, turn off Background Rendering.

• My mac does meet the requirement for Final Cut Pro 12.3
• I created a new library and imported a single clip in it, it did not change the result.
• When I try "Frame blending", it does work as expected, so the problem is specific to "Optical Flow".
• I don't even see the "Best (Machine Learning)" option in my version of FCPX. I used to see it greyed out in a prior version if I remember correctly. Anyway, my problem is with Optical Flow, not Machine Learning.

I have a 2019 intel Imac running Sequoia 15.7.9

3,6 GHz Intel Core i9

8 cores

Radeon Pro Vega 48 8 Go

72 Go 2667 MHz DDR4

I tried to slow down .mov footage shot with a Sony FX30 (XAVC S 4K - 4:2:2) and also on a simple H264 .mp4 file. The outcome was the same : choppy.

Thank you for your answer, I do think the problem is due to the software and not how I use it.

I had been using Optical Flow for years without any problems before this.

How much available disc space do you have?

Have you trashed your preferences?

Have you tested for this problem across different Projects, different Libraries?

pgtipster wrote:

. . . specifically when trying to apply Better (Optical Flow) to native footage.

What format is native footage?

MtD

Hey,

On the project drive I have 870gb available

On the Mac HD I have 30gb available

I trashed my preferences, It made no difference.

It happens in all projects and libraries.

It doesn't seem to matter what the footage is, can be 422 or MXF.

update to 12.4 has made no difference either.

I've tried reimporting the footage into another fresh project. I get the same results.

I've found quite a few other people complaining of this on Reddit.

Surprised my post isn't getting more response.

Hope that helps.

I have the exact same problem on a 2019 Intel iMac running FCPX 12.3

The clips have been analysed and rendered but still play very choppy (export is the same), a problem I didn't have before.

Deleting the render files, the analysis files and Final Cut Pro preferences didn't change anything.

I tried to apply the optical flow to different kind of codecs and video files, the results remained the same.

And I have plenty of space on my drive.

It's all very frustrating, because it used to work perfectly…

I noticed something similar in FCP 12.4 an hour ago.

I had some jittery 25p footage shot at 1/800 sec so I retimed the clip to 101% and added Optical Flow. It analysed the clip which played back silky smooth.

I tried it again and there was no analysis and even after rendering the clip remained the same.

Yes, of course I did.