[Joe Marler]

Normally that is not necessary, at least on a 2017 or later iMac. However if you use compute-intensive effects such as Neat Video noise reduction on many clips, the timeline can become very slow.

To avoid this the prudent approach is do pure content editing first, then later apply normal effects and color correction, then at the very end apply the compute-intensive effects such as de-flickering, stabilization or video noise reduction.

There are some camera codecs which are very sluggish to edit with FCPX (even minus effects), such as Panasonic’s 4k 10-bit 4:2:2 All-I. You can significantly improve that or the Fx performance issue by creating proxies, which by default are 50% resolution ProRes Proxy codec.

Re crashing, in general FCPX has very good data integrity and automatically makes periodic backups in /Movies/Final Cut Backups. However it is a good practice to import all media with “leave files in place”, and in the library inspector define external locations for other media and cache. Select the current library in the left side bar, then in Inspector pick Storage Locations>Modify Settings>Media and also Cache. That keeps the library bundle itself very small so you can periodically duplicate it in Finder for another backup method.

With FCPX in general you want to avoid a workflow that requires frequent copying clips between projects. To do this first curate the material using rejects, favorites and keywords.

Create and sync all multicams first, then mark “rejected” all parent clips composing those and run the browser filter in “hide rejected”. Mark any additional rejects, favorites or keyword ranges on the multicam clip itself in the browser, using the Angle Viewer (SHIFT+CMD+7). This avoids accidentally editing into a timeline a non-synchronized parent video or audio clip. In general use multicam clips (not sync clips) even if you only have a single video and external audio source.

There is nothing wrong with using a separate timeline per act if you want to.

[Joe Marler]

No, ProRes originals or optimized media would not by itself make a difference. However it would change the *ratio* of original/optimized media to render cache. A 60 second 3.2 GB 4k ProRes 422 clip rendered to cache would take about 3.2 GB, or roughly 1:1. By contrast a 60 second 4k H264 clip might be 700 MB and if rendered to cache might also take roughly about 3.2 GB, or roughly 4.5:1. So the total space consumed would be about the same per minute of 4k material, but as a ratio of original file size to rendered cache size, the ratio would be larger.

[Joe Marler]

FCPX automatically, continuously backs up all work from all libraries in /Movies/Final Cut Backups. These are very small and contain no cache, media or render files.

For off-site safety, copy theses libraries to other locations. I would duplicate them then compress or ZIP them which includes an embedded checksum.

If you use “lean” libraries (no media, proxies or cache), these are easy to back up at a Finder level. Just duplicate them, compress and copy to a backup location. They are very small. To use lean libraries, import data using “leave files in place”, also use the library inspector Storage Locations>Modify Settings>Media and Cache to define external locations. For details see Ripple Training’s class which is well worth it: https://www.rippletraining.com/products/final-cut-pro/media-management-in-fcp-x-10-4-9/

The FCPX automatic backup frequency is not adjustable, but is determined by edit rate, which in practice might be every 15 min or every 60 min. You can get a Mac app to do this manually at a rate you specify: https://apps.apple.com/us/app/backups-for-final-cut-pro/id586594646?mt=12

To reduce space consumption from cache or other non-essential files, use Final Cut Library Manager: https://www.arcticwhiteness.com/finalcutlibrarymanager/

[Joe Marler]

You were just fortunate before. Segments within the FCPX render cache are constantly being invalidated for various reasons. If the timeline is fully rendered and you merely tweak a color effect, that clip’s cache is invalidated, then gets automatically re-generated (if background rendering is on). Yet the previous cache files just sit there. If you edit a clip 20 times, there are 19 versions of stale ProRes 422 cache files just sitting there taking up space.

If you have an adjustment layer or title over the timeline and tweak that, all clips in the covered range are re-rendered. The previous cache files are marked invalid but stay in the cache folder.

If your source clips are H264, in general *each* version of the ProRes 422 cache files are about 6x that size. So it is very easy to have space consumption by the render cache which is *much* larger than the total media size.

Proxies have their own separate cache files. The proxies alone (not the proxy render cache) are roughly 60% the size of H264 originals, if using default 50% ProRes Proxies.

So for a single 30-second 4k H264 8-bit clip using 100 mbps encoding, the camera file is 373 MB. A single render file cache of that clip will be about 6x larger or 2.14 GB. If you make 10 edits to the clip, then background rendering could re-render it 10 times, occupying 21.4 GB.

Proxies have their own render cache, which is about 120% the size of the H264 original. E.g, if the original 30 sec. 4k camera clip is 373 MB, *one* instance of proxy render cache of that is 456 MB. If you edit that clip 10 times in proxy mode, that is 4.56 GB in proxy render files.

So the total cache space consumption of editing one 30 sec clip 10 times in orig. media mode then 10x in proxy mode would be about 21.4 + 4.56 GB or about 26 GB for an original 373 MB camera clip. You might think “I’m not editing the clip 10 times”, but any change to any clip above or below that in the timeline stack will cause all clips covered by that range to be re-rendered.

Also render cache segments can become invalid for non-editing reasons. Sometimes if you just re-launch FCPX, portions of the timeline may become un-cached. Sometimes switching between proxy and orig. media mode will cause this. Some of these may be bugs but if background rendering is on, it causes additional space consumption.

To be exact, the full stack depth of all clips in a *range* are invalidated and re-rendered, not just whole clips. There are not separate render cache files per clip in the stack, but render files are per range, just like you exported a ProRes file from a five-layer timeline. But for this simple analysis it’s simpler to think in terms of single clips.

[Joe Marler]

FCPX does not delete old or invalid render files. If you have background rendering enabled, they can build up to a huge total size.

Disable background rendering in FCPX preferences, then delete all render files via File>Delete Generated Library Files>Delete Render Files>All.

Then manually render clips only as required. You can select clips or the entire timeline with CMD+A, then render to cache with CTRL+R.

However that does not delete waveforms, thumbnails or optical flow analysis files. An easy way to safely delete all those (plus render files) from multiple non-mounted libraries is using Final Cut Library Manager: https://www.arcticwhiteness.com/finalcutlibrarymanager/

[Joe Marler]

The stabilizer in Resolve works well. Resolve’s stabilizer is within the tracker menu of the color panel. You can select the anchor region you want stabilization based on. It’s a separate tool, so so you’d need to export a ProRes clip, import to Resolve, stabilize, export, and import back to FCPX. It’s available in the free version of Resolve but the paid version has additional stabilization options.

[Joe Marler]

Here are some green screen tips:

https://youtu.be/FGWMQCJbNxo

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[Joe Marler]

Yes, 1080p in a 4k timeline is fine. In the inspector pane, by default FCPX uses spatial confirm>fit. There is a scaling issue that may slightly degrade resolution IF using 4k in a 1080p timeline and exporting as 1080p, vs using 4k in a 4k timeline and exporting as 1080p. The severity of this seems to vary based on the source codec.

Here is a test I previously did on this issue: https://joema.smugmug.com/Image-Tests/n-d3hVjt/

There is limited performance cost to using mixed 1080p and 4k in a 4k timeline for 1080p export. The internal render files are bigger but in most cases the performance cost is small.

For Youtube export at the best quality, I’d suggest this preset: File>Share>Master File>Settings, Format: Computer, Video Codec: H.264 Better Quality, Resolution: 3840 x 2160.

Most Youtube playback will be at 1080p or below, but starting with a 4k upload can give a better result.

Another common quality issue is mixed frame rates. Slow motion is OK since it’s played back slow, but if you have mixed 23.98 and 29.97 material played at 1x rate this can cause jerky motion cadence. The solution is select the clips that don’t match the timeline frame rate, then in the FCPX video inspector, scroll to bottom and under Frame Sampling, select Optical Flow. Then select that clip in the timeline, render with CTRL+R, and examine the playback smoothness.

If after re-encode on the Youtube server, there are any visible issues during streaming playback such as banding, you could try a short test exporting as ProRes and uploading that. Another possibility is exporting as ProRes then using Handbrake to transcode to 10-bit HEVC, which is much smaller and preserves more tonal data, then upload that. Unfortunately current versions of FCPX do not use hardware acceleration for 10-bit HEVC, so are impractically slow. You must use some other software for ProRes to 10-bit HEVC transcoding.

[Joe Marler]

This person offers 1:1 remote training on FCPX. I have no relationship with him, I only noticed his Youtube channel: https://www.youtube.com/channel/UCOE_zSaeU1xd9yIk6kfwf_A

Ben Halsall has many free tutorials on FCPX. I don’t know if he offers 1:1 training: https://www.youtube.com/channel/UCQbfC3DLce4TYulsmwf2lzQ

Ripple Training also has excellent low-cost tutorials. They are very comprehensive and have high production standards. Ripple allows download of their tutorials so you can watch them at high speed and independent of a network: https://www.rippletraining.com

This book was just released, “Final Cut Pro X Efficient Editing” by Iain Anderson. It is available in Kindle format. I just got it but haven’t read it yet. It looks very good: https://www.amazon.com/dp/B08FCRNTT9/

[Joe Marler]

The most common cause of crashes on old version of FCPX are 3rd-party plugins or the above previously-mentioned iTunes update issue. Running the Chrome browser can also destabilize FCPX due to it mis-using the Mac VideoToolBox framework. For troubleshooting purposes, temporarily discontinue any use of Chrome or any browser based on Chrome such as Brave.

Make sure you have plenty of free disk space on all drives, at least 20%. All drives should be only HFS+ (Mac OS Extended Journaled) or APFS, nothing else.

If you have never run Disk Utility First Aid, run that on all drives. To run properly on the MacOS system drive requires first booting into recovery mode: https://support.apple.com/guide/disk-utility/repair-a-disk-dskutl1040/16.0/mac/10.13

If your entire machine every hangs or crashes (not just FCPX) that is a system-layer problem which cannot be fixed at the application layer.