Broken file or unsupported format?
| Test | Result | What it means |
|---|---|---|
| Open it in VLC or IINA | It plays | The file is fine. QuickTime doesn't support its codec, for example an MKV, a WebM, or an AVI from an old camera. Keep using VLC or IINA. |
| Look at it in Finder with Get Info | The size is normal but no duration or dimensions show | The index is probably missing. |
| Open it in VLC | Black window, 0:00, or nothing | The file is broken. Repair it, below. |
Why MOV and MP4 files break
A MOV or MP4 keeps an index, the moov atom, that lists where every frame sits. Cameras and iPhones write it when the recording stops. A recording cut off by a dead battery, a crash, a full card or a copy that broke off has its footage and no index, and QuickTime can't open what it can't find.
Repair it in your browser on the Mac
- Open this page in Safari, Chrome or Firefox and drop the broken file on the checker. It reads the file on your Mac; nothing is uploaded.
- The free check tells you whether it found pictures and sound.
- If it asks for a clip, give it a video that plays, recorded on the same camera or iPhone with the same settings.
- Watch the free 15-second preview, then download the full video for $4.99, or with a plan. If it doesn't play, write to support@nasrtech.dev and we'll look at it with you.
The repaired file opens in QuickTime when its codec is one QuickTime plays: H.264 and H.265 video with AAC sound are.
Other ways on a Mac
- Untrunc, free and open source, has no ready-made Mac app; you build it from source with Homebrew and run it in Terminal. There is no
brew install untrunc. See Untrunc on Windows and Mac. - Stellar Repair for Video and Wondershare Repairit sell Mac programs. Stellar's Standard edition is $49.99 on an offer ending 16 November 2026; Repairit's Mac pricing is on its own page (stellarinfo.com and repairit.wondershare.com, checked 2 November 2026).
What a user wrote
"Very useful app for recovering damaged or unplayable videos. I like that you can repair the file and preview the result before paying to save it." (Google Play review of the Video Repair app for Android, same engine, September 2026)
