Repair a MOV file that won't open

MOV and MP4 share one structure

Apple's QuickTime format stores a movie as a chain of labeled blocks that Apple calls atoms. ISO based the MP4 format on QuickTime, and the MP4 standard calls the same blocks boxes. A MOV breaks the same way an MP4 does, and the tool above repairs both.

Two atoms matter for a repair. The mdat atom holds the compressed video and sound. The moov atom is the index: where each frame starts, how big it is, how long the clip runs and the codec settings a player needs to decode it. Apple's file format specification says an app can make sense of the media data through the movie atom and no other way.

iPhones save their videos as MOV, in HEVC or H.264 depending on Settings > Camera > Formats, and a Mac saves its screen recordings as .mov files. Several Nikon and Fujifilm cameras offer MOV next to MP4.

The camera writes the moov atom when you press stop. If the battery dies, the app crashes or the card comes out before that moment, the file keeps its footage and ends up with no index, so players can't find a single frame.

Reading QuickTime's error

QuickTime Player answers a MOV it can't read with this message:

The document "clip.mov" could not be opened. The file isn't compatible with QuickTime Player.

The same words cover two different problems. One is a format QuickTime doesn't read, such as an older codec that newer versions of macOS dropped. The other is a broken file, such as a recording that lost its index. The message alone can't tell you which one you have.

A different warning appears with some H.265 files: the file contains media which isn't compatible, and you hear sound with no picture. That one means QuickTime read the file's structure, index included, and couldn't decode the video track.

Free checks before any repair

1. Copy the MOV to another folder and work on the copy.
2. Open it in VLC. VLC carries its own decoders, so if the file plays there, the file is readable and QuickTime lacks the codec. VLC's built-in repair handles AVI files and won't fix a MOV.
3. On a PC, Windows' own players need Microsoft's HEVC Video Extensions to show an iPhone video recorded in HEVC. VLC plays it without them. To record H.264 from now on, set the iPhone to Settings > Camera > Formats > Most Compatible.
4. Check the size. A file of 0 KB holds nothing to repair.
5. If the MOV came from a download, a transfer or a copy that might have stopped partway, get it again from the source. Many cameras write the index at the end of the file, and a copy that stops short leaves it behind.

If VLC can't play the file either and its size looks right for the length you recorded, suspect the missing index.

Repair the MOV in your browser

The tool above runs the engine of the Video Repair apps for Android and Windows, compiled to WebAssembly. It reads your MOV from your own disk and never sends it to a server.

1. Choose the MOV in the tool above.
2. The free check reads the file and reports whether it found footage it can rebuild.
3. If the tool asks for a reference clip, add one from the same camera.
4. Watch the free 5-second preview of your own footage, at reduced quality with a watermark.
5. To save the full video, pick a plan: one video, three months or a year. You can cancel anytime, and if the repaired video doesn't play, you get a refund.

The tool re-encodes nothing. Your repaired file holds the camera's own video and sound data, byte for byte, with a new index written around it.

The reference clip

Some cameras keep their video settings in the index and don't repeat them inside the footage. AAC sound settings live in the index too. For those files the tool asks for a reference clip: any healthy video recorded by the same camera at the same settings.

Match what the camera menu shows: resolution, frame rate, HEVC or H.264, and the HDR setting on an iPhone. If you have no older clip, record a short one now with the same camera and settings. The reference supplies the missing settings and, if the sound is gone too, brings it back.

Files the tool can't repair

The tool works on MOV, MP4, M4V and 3GP files with H.264 or H.265 video and AAC sound. It can't help with:

• ProRes MOV files, which iPhone Pro models and pro cameras can record.
• Sound recorded as uncompressed PCM. Several Nikon and Fujifilm models record PCM sound in MOV files and keep AAC for MP4.
• Deleted files. The tool repairs a file you have and can't undelete one.
• Footage that was overwritten or never written, such as a file that is empty or all zeros.
• AVI, MKV, TS and WebM files, which it doesn't support yet.
• Files hidden by vault or "hide video" apps, which it can't decrypt.