Final Cut Pro mp4 file export silently quits

Claude, I was reviewing your initial description. If there is any chance you are applying a magnetic mask to an unbroken 30 min video, that explains why the export is so slow. It's not the disk or anything else.

The magnetic mask effect is really designed to be used on shorter clips, not an unbroken timeline. If used on a clip over about 12-15 minutes duration, there is an exponential performance degradation which affects both playback and export. This persists even if the clip is fully rendered to cache.

The magnitude of the slowdown is severe, about 50 times slower export performance on 15-minute clips than 7-minute clips. A 30 minute clip (or timeline) would be slower still.

This is apparently by design in the current implementation. A mask validation system examines the entire timeline's worth of analysis records to make decisions about the current frame. This happens even if the timeline is fully rendered to cache.

The extreme compute load on a lower-end machine, along with other factors, might explain why the export halted.

If you must use a magnetic mask on an entire timeline, there is a very simple workaround: do a "through edit" about every 10 minutes, then apply the mask separately to each 10-minute region. That should be vastly faster.

A possible cause of crashing during export is a corrupt frame or frames.

Try splitting your timeline into several parts and export them separately.

If the problem is caused by corruption you will be able to find it by a process of elimination.

It should be higher than that, but it's not in the extremely slow state some T7 SSDs get stuck in (about 2 megabytes per second write speed).

Please run your export and after a few minutes do the below terminal command and send me the results. For this pass, it's not necessary to reproduce the problem. It will ask you for your password, so enter that.

 sudo log show --last 60s > ~/Documents/LogShow_60s.txt

This writes the previous 60 seconds of unfiltered MacOS system log to a file. Then compress that and upload it to me here: https://we.tl/r-bVW2bg3eO7

That is in hopes that it will show something even before your problem manifests. Ideally, I'd like to see that log capture immediately after the problem happens, but I understand you cannot predict that.

If you think you can detect the problem within 5 minutes after it happens, then run this command. It dumps the MacOS system log for the previous 5 minutes to a file, then compress and upload that file to the above link. That output is very verbose, so that's why it must be restricted to just a few minutes, max.

sudo log show --last 5m > ~/Documents/LogShow_5m.txt

There are known issues with the Samsung T7 whereby the writing performance can severely degrade. Please run Blackmagic Disk Speed Test on that drive and report both write and read numbers.

In general, creating iteratively nested "Russian doll" clips of combined composite and multicam clips, each containing multiple compute-intensive magnetic mask effects, composited on a background of Motion 3D fonts, will produce very slow performance. This will be especially noticeable on a lower-end machine.

This is further aggravated by any multi-frame effects. Those are effects which operate on a sliding window of frames, not just a frame at a time. If two multiframe effects are in the stack, that can cause exponential performance cost, because for each frame in the window of a lower effect in the stack requires recomputing all frames in the window of an upper effect in the stack. In some cases, depending on the effects, it also prevents caching those results. Which effects are multi-frame is not documented.

However you can't be blamed for using effects this way. The features are there and people will use them. There is no guidance in this area about the performance impact of certain combinations of timeline constructs, effects, and compositing methods.

In general FCP is very fast. Making normal, single-layer use of multicam is OK and conservative use of compound clips is OK. Most of the built-in FCP effects are very fast.

But certain combinations of those in certain timeline constructions can be very slow. Those of us who have used FCP for many years sort of figure that out, but it really should be documented in some manner.

Over the years, I've had pointed discussions with Pro Apps escalation support about this. I believe their viewpoint is that documenting specific performance behaviors would lock in people's expectations on version-specific details that could easily change in the future.

There is also an issue with whether any support tier has the procedural authority to do that, not to mention the time and expertise required. Obviously, engineering could do that, but it would take lots of time to do properly, and then it would be subject to rapid obsolescence as new versions and machines change.

The situation is similar with DaVinci Resolve. People frequently run into performance "blind alleys," and (even though the manual is 4,500 pages) those cases are not documented.

I have not had time to watch all of it so I have just skimmed through some sections. Yes, it does look as though the timeline could be a bit complex so in future just do sections at a time and after you have exported each part combine them all onto a new timeline for the final export.

A couple of initial comments . . . the rotating title at the start is too fast to be readable (it jitters) and "The Big H" has fonts so ornate that it too is very difficult to read.

I was only able to get through 70% of the description of the metaverse but maybe I am too slow a reader. ☹️

In the olden days of celluloid film a general rule of thumb was to leave any writing on the screen about twice as long as a normal person could read. That may be a little excessive nowadays as we have universal education but you do need to allow more time.

If it's any consolation, I find writing on current Hollywood movies appears too briefly but once again it may be my slow reading . . . after all I was only a Junior School teacher. I had no problems in the old silent days watching Charlie Chaplin and Buster Keaton but of course I was helped by the rest of the audience reading the words aloud in unison . . . Happy Days.

All you need to do is slow down the title and export it.

Then import it and the already exported full video which will be 1080p .mp4s I presume.

Put them in the timeline replacing the original titles with the edited titles and export them . . . . which should not take more than 15 minutes.