iMovie exports with random glitches

There have been several reports of random glitches with exporting from iMovie. It seems possibly related to videos taken on newer iPhones. No answer as yet.

Would you post back and let us know whether your video clips were recorded with an iPhone and if so, what model.

— Rich

Narrowing the issue further, the issue seems to occur on newer iPhones that have recorded the video in HEVC format. If that's the case, the cure is to use a video converter like Handbrake to convert the HEVC clips to H.264.Mp4/AAC, that Handbrake will do by default. For future videos go to your iPhone Photo settings/Transfer to PC, automatic to transfer the video in the most compatible format.

-- Rich

I don't know for sure that the problem is HEVC with Catalina. There just appears to be a correlation from the reports that have been posted here. Open one of the clips in QuickTimePlayer and from the QuickTime menu do a Window/Show Movie Inspector. In the box that appears check the format and see if it is HEVC (or H.265). If it is HEVC, then export it from iMovie and see if you get glitches. If you get glitches then HEVC might be the problem. If the format is not HEVC, and you still get glitches on export, then HEVC is not the problem.

As I mentioned, for future iPhone exports you can set your iPhone settings (Settings/Photos/Transfer to PC or Mac/Automatic) to export in the most compatible format. In the event that you still have the videos on your iPhone you can use that method to re-export in the most compatible format. If you already have exported the videos and no longer have them on your iPhone, you can open the HEVC video in QuickTime Player on your Mac, choose File > Export As, then save to H.264 by making sure the HEVC checkbox isn’t selected.

I have no idea what Apple might or might not do regarding this issue.

-- Rich

I'm having this issue too. Video recorded with iPhone 8Plus, iOS 13.2. Perfect video in original clips and in the iMovie timeline, but random frames from other clips appearing in exported videos.