I just finally came across a problem I (or googeling) couldn't fix myself. And I am hoping somebody else might have this issue.
I do a lot of filming with smaller Sony cameras, and the preferred codec these record in is XAVC-S. In the newest FCPX version (10.4) however, these files play back and export with a strange effect. Whenever there is a larger green or red object in the frame (or turquoise or dark orange, this is not pure red or green), this object and nothing else seems to flicker in brightness and saturation. Not regularly, but now and then, on average maybe twice per second.
I have definitely not seen this before in FCPX, only since version 10.4. It does not depend on the bitrate or framerate (tried changing those) or camera (recording to MP4 files works fine). The files also play back fine in other players, including Quick Time, just FCPX seems to have a problem with them.
I just wanted to know if anybody else has seen this, and (hopefully) has an idea how to fix it... If you would like an example file, I can send you one (what service should I use for file transfer in this forum, ideally?).
Had this exact issue with AVCHD footage - found the solution was to use 'Override Color Space' on the settings tab of the Inspector (when selecting the source media) to force it to Rec.709. Have reported the bug to Apple - seems like FCPX is jumping between Rec.709 and Rec.601
@matt.brading: Thank you so much! This was precisely the issue, and your workaround fixed the problem. Glad to hear that you already reported it, this is an actual bug and should hopefully be fixed soon.
@MichelangeloTorres: Recoding wasn't really an option. We are talking about hundreds of GBs of footage, which would amount to like a dozen TBs in ProRes, I was very glad to edit in XAVC-S directly.
This forum never seizes to amaze me, I wouldn't have expected such a simple and quick answer.