Guide
QuickTime says your MOV isn't a movie file
The Mac opened that file yesterday and won't today — or never opened it at all.
Two checks to run right now, free
Open it with VLC or IINA instead of QuickTime: right-click the file, Open With, and pick either. QuickTime accepts few formats and has dropped support for older encodings, so it refuses perfectly healthy files too. If either one opens it, the video is fine.
Then look at the file's info: right-click, Get Info. If the size is a few kilobytes or the duration reads 0:00, the problem isn't the player — the content was never written.
What that message means
"The document is not a movie file" means QuickTime opened the file and didn't find the structure it expects from a video. It isn't saying the file is empty: it's saying what's at the start doesn't look like a movie to it.
On files recorded by cameras and action cams this happens because recording stopped before the index was written, and in MOV files the index lives at the end. On files that came from elsewhere it happens because the transfer stopped halfway: the file is there but shorter than the original.
First things first: is your file recoverable?
The check takes two seconds, it's free, and the video is never uploaded anywhere: the analysis runs inside your browser, on your own computer.
See if it's recoverableWhat not to do, under any circumstances
- Don't rename the extension from .mov to .mp4 hoping it will open: the content doesn't change.
- Don't run some random program's repair function on the only copy you have: make a copy first.
- Don't empty the trash if you've just deleted the good version by mistake.
- Don't re-copy the file from the card over the one already copied: if this copy is the interrupted one, you lose the earlier attempt too.
If no player will open it
The free check above looks at how the file is built and tells you which case is yours: missing index, truncated file, or lost header. Three different faults, and the remedy changes.
If the file comes from a camera or a phone, putting the index back needs a second video shot on the same device with the same settings. Three seconds filmed right now will do.
Questions I get every time
The file was on an external drive and now it won't open.
Check the size first: if it differs from what you remember, the copy was interrupted. In that case it's worth copying it again from the source, if you still have it, rather than working on the truncated copy.
iMovie says the file isn't compatible.
iMovie is even pickier than QuickTime about formats. That isn't a diagnosis of the file: try VLC first, which will tell you whether the video is readable at all.
The video plays but with no sound, or the other way round.
The two tracks are separate inside the file: one can be readable while the other isn't. What's there gets recovered, and often the other one too by working on the structure.
If you'd rather I handled it
You send me the file and the reference video, I send you a preview of the recovered one, and only then do you decide whether to pay. Twenty euros per video, thirty-five for up to five files from the same device.
You only pay if the video turns up.