Contrary to what you might read online or what the dumb robots might tell you (because they just plagiarise it from those same Reddit threads and YouTube videos), you can’t simply “Expand Audio” and apply the Cross Dissolve to just the video lane¹. You can detach the audio entirely, but that’s heavy-handed and may make your life much harder downstream (since Final Cut Pro will then treat the separated audio and video as completely independent clips).

Actually, there’s a simple ‘hack’ which works:

1. Drag the Cross Dissolve (or similar) onto the clip.
2. Select the clip and “Expand Audio” (from the Clip menu, contextual pop-up menu, or by pressing ⌃S). This is really just to get access to the audio track that’s otherwise hidden under the Cross Dissolve.
3. Carefully drag the audio fade-in handle to the edge of the clip, to exactly where the tooltip says the offset is zero. Don’t go too far – if you go over the end of the clip it’ll re-install the audio fade!

It feels like that shouldn’t work – like it’s actually a subtle bug where Final Cut Pro actually intends to ignore your zero-duration fade-in and reset it back to the full length, like it does if you drag just a pixel too far. But hey, thank goodness for some bugs!

1. Maybe this did work in an earlier version of Final Cut Pro, but it definitely does not in 11.2. ↩︎

Steps:

1. Duplicate the clip (option-drag it in the timeline view) and place the duplicate above¹ the original. Ensure it’s perfectly aligned on the timeline’s X (time) axis, otherwise it won’t show up as a tracking source in step 3.2.
2. On the duplicate clip (make sure it’s selected and your playback position is within it so that you can see what you’re doing!):
   1. Invert the scale (e.g. make it -100% instead of the default 100%).
   2. Invert the X & Y offsets (if necessary – if they were non-zero beforehand).
   3. Add an Object Tracker (the + icon to the right of the “Tracker” titlebar at the bottom of the Video Inspector (right-hand pane)).
   4. A white grid – your anchor section – should appear over your clip. Move and resize it to have it cover an appropriate part of the clip (a subsection that’s contrasty and contains object(s) that are stable – in appearance and position – within the world space of the scene, and ideally are never obscured by anything during the clip).
      • ☝️ You can adjust the timeline position of the clip to find the optimum frame in which to identify your anchor section.
   5. Click Analyze.
      • ⚠️ This will sometimes not work if certain other operations are outstanding, such as dominant motion analysis for the clip – you have to either cancel those background tasks or wait for them to finish. One of Final Cut Pro’s many irritating bugs.
      • ⚠️ Watch carefully as it works through the clip (forwards from your starting point, then backwards, as necessary), for:
        • Your anchor section being intruded upon by any moving objects within the scene. If that happens, try to go back and refine your anchor section placement so that it won’t be intruded upon. If that’s impossible, you can proceed but be aware that the results may be subpar.
        • The anchor section changing in position and size – the more it ‘wobbles’, the worse the final results are likely to be. Consider different anchor section placement, or try a different analysis method (in the Video Inspector, for your Object Track, change the Analysis Method from the default, “Automatic”, to another option – note that you must click Analyze again after changing this, for it to take effect).
3. On the original clip:
   1. Open the Transform viewer (the rectangle icon in the “Transform” titlebar in the Video Inspector).
   2. Click the downward chevron next to “Tracker” text on the Tracker tab button (at the top of the video preview view), to bring up the configuration pop-up:
      • Set Tracker Source to your duplicate clip.
      • Set Tracker to the Object Tracker (or whatever you renamed it to).
      • Set the axes you want stabilisation to apply to (the Apply Tracker To checkboxes).
4. Disable the duplicate (e.g. V key while it’s selected).
   • ☝️ You cannot have it disabled before you select it as the Tracker Source, as it won’t show up in the pop-up menu while disabled.
5. On the original clip:
   1. Set the scale to -100%.
   2. Adjust the X & Y positions to correct the framing, if necessary (if your X & Y position were both 0 on the original clip, this shouldn’t be necessary). Note that this usually isn’t a simple sign inversion as in similar previous steps.

Optional sixth step: file a bug report or suggestion with Apple asking for them to make their built-in image stabilisation work better, and/or make the object tracker GUI easier to use (it could be just one or two clicks, to enable it and say “lock this part of the scene in place”).

1. Technically it doesn’t matter if it’s above or below, I just find it slightly more convenient when it’s above as usually it’ll be disabled (showing the original, now-stabilised version from below) but I access it easily by simply enabling it (V key), such as if I want to adjust the tracking. ↩︎

In short:

1. File > Library Properties (⌃⌘J).
2. Click “Modify Settings” next to “Storage Locations”.
3. Set the “Backups” option to “Do Not Save”.

My projects are already covered by Time Machine and other backup mechanisms, and I tried to tolerate Final Cut Pros built-in backup system, but the damn thing runs so often, which I know about very well because whenever it runs Final Cut Pro becomes completely unusable for several minutes. It’s immensely irritating when it kicks in while I’m in the middle of editing.

However, Final Cut Pro has a design flaw which causes data loss. You see, Final Cut Pro never merely copies the files. It extracts their audiovisual contents and puts it into a new file. You might have noticed this already from the fact that Final Cut Pro’s copied version of the files is always a MOV container, whereas your inputs are more likely an MP4 container.

This would be annoying enough in itself – it means you can’t do simple bitwise comparisons of the files to e.g. ensure the imported copy is actually valid and not corrupt, before you erase the original from your memory card. But it gets worse.

Final Cut Pro doesn’t copy all the contents. It only copies some types of tracks – i.e. audio, video, and timestamp tracks. It does not copy tracks such as GoPro’s metadata track (GPMD). Final Cut Pro just silently discards those.

Those tracks can contain important information. GPMD tracks, for example, contain a whole host of telemetry from the GoPro including its location during recording, rotation & movement data, and much more. Even if you think you don’t care about things like geotagging, consider this: that rotation & movement data can be used to enhance image stabilisation. By losing the data at import, you’re losing the ability to ever utilise that enhanced image stabilisation.

So never let Final Cut Pro “copy” your files – always copy them yourself first, as needed, and then import them into Final Cut Pro by reference only (the “Leave files in place” option). Thankfully Final Cut Pro doesn’t mangle the files when you use them that way (underlining the question: why does it force a lossy conversion to MOV to begin with, since it clearly works just fine with MP4 originals).