Repair a corrupted DJI Mini 4 Pro video

An MP4 stores its index — the moov atom that maps every frame — only when the recording is finalized. On a drone, the recording often isn't allowed to finish:

• The battery ejects on a hard landing or crash. The Mini 4 Pro is a sub-249 g aircraft; a bad touchdown or a clip on a branch can pop the pack out and cut power to the camera mid-write.
• The drone is powered off too soon — you hit the switch, or a low-battery auto-landing shuts things down — before the current clip closes.
• Signal loss or flyaway ends a flight abruptly, so the last file on the card has footage but no index.

In every one of these cases you get the same result: a file with real H.264 or H.265 data and a missing or truncated tail, which is where the index should have been. DJI even documents a first-aid step for this — put the card back in the aircraft, power-cycle it, and wait about 30 seconds to see if the camera restores the file itself. Try that first. When it doesn't work, the file needs a real container rebuild.

The classic desktop tool for this is djifix, and understanding what it does explains the whole problem. On a file with no moov, djifix salvages the raw stream and writes a bare .h264/.h265 elementary file — video only, no audio — which you then have to remux into a playable MP4 with the correct framerate. It also needs the original, untouched file straight from the SD card, and only recent builds handle the newer H.265 modes (support for 4K/100 H.265 was only added in early 2024). It's effective, but it's a command line, and the output isn't a finished clip.

A container rebuild takes the same surviving data and reconstructs the sample tables so the result is a normal, playable MP4 — no remuxing step. Because Mini 4 Pro footage can be 10-bit H.265 with an unusual frame structure (especially the 4K/100 slow-motion and D-Log M modes), a healthy clip from the same drone at the same settings is the ideal reference: it carries the exact codec configuration and framerate the broken file is missing, so the rebuild is faithful. Any normal clip from the same card, shot in the same mode, will do — keep one handy.

Drone video is location data by nature — it shows exactly where you flew, over whose property, and often people who never agreed to be filmed. If the flight is tied to an incident, a client job, or an insurance claim, that clip is evidence, and DJI files carry embedded flight metadata on top of the picture. Upload-based repair sites take a full copy onto servers you can't inspect, under terms you didn't write.

Here the repair runs entirely in your browser: the file is read from your disk, rebuilt in the tab, and saved back. Nothing is transmitted, and you can prove it — open the Network tab and watch 0 bytes of the clip leave your machine. That's the property you want for footage that might end up in a claim, and it means a large 4K file never waits on an upload.