by Larry Jordan
Earlier today, Richard W. sent me this question: “Something came up that I [need explained.] …The auto-update on my MacBook Air Mojave prompted me to update iMovie from version 10.1.1 to 10.1.11 with the curious message: ‘Detects media files that may be incompatible with future versions of macOS and converts them to a compatible format…. I really hate the idea of any software converting my media files without my clear understanding and approval so I didn’t update this iMovie software… I wonder if you know anything about this?”
Yes, and it is critically important that you understand the answer. Apple has deprecated all codecs based on QuickTime 7. If you upgrade to the next version of macOS AFTER Mojave, media using these codecs WILL NOT PLAY and CANNOT be converted! In other words, if you ignore this warning and upgrade, you are screwed. (Here’s an article that explains what is happening.)
What Apple has done, before the next OS upgrade, is provide a conversion utility in Final Cut, iMovie, Compressor, and Motion that recognizes these out-of-date codecs and converts them into something more future-proof; specifically ProRes 422. What this feature does is recognize when you’ve opened media which will soon be obsolete and gives you the ability to convert it. This conversion is NOT automatic, nor behind-the-scenes. You have to click OK for the conversion to occur. However, if you DON’T convert your media, you will not be able to upgrade to the next version of macOS. (Here are two articles illustrating this conversion process in Final Cut Pro X and Compressor. Compressor is more flexible.)
Please, to prevent future problems, read my background article above and these newer ones showing how this process works. Because, once you upgrade macOS, you can’t go back and you can’t play your older media. Also, if you are debating what to do, please turn OFF automatic updating of your system. Here’s an article that explains how. This will prevent unexpected, and unpleasant, surprises.
And of course, backup your data, just in case!