Field notes
The battery ran out mid‑flight, you hit the power button, or the drone came down harder than planned. The clip is on the card and nothing will open it. Here is what to try, in the order that costs you least, starting with what DJI can do itself.
Do not record anything else on that card. The one exception is step one below, which is done deliberately and in the drone. Otherwise take the card out and copy everything off it first. Nothing recovers footage that has been written over.
This is the one that most often works, it is free, and it takes a minute. Put the original card back in the aircraft or camera that shot it, power on, wait about thirty seconds, then start a recording and stop it again. The camera notices the recording it never finished closing and finalises it.
Do this before copying files around, and before trying any software. It is far more likely to succeed while the card is still exactly as the drone left it.
DJI writes a .LRF alongside each recording: a low resolution proxy of
the same footage, used for playback in the app. It is written separately from the
main clip, so it is often perfectly intact when the big file is not.
Copy the .LRF with the matching file number and rename the copy to
.MP4. If it plays, you have your flight. It is not the resolution you
shot, but it proves the footage exists, and for a moment you thought was lost it is
frequently enough.
If the clip is a sensible size rather than zero bytes, the video is almost certainly still inside. What a camera writes last, when recording stops cleanly, is the index saying where every frame lives. Lose power first and you have a complete recording with no map, which every player refuses to touch.
On a Mac, this tells you which case you are in:
ls -l DJI_0042.MP4 strings -t d DJI_0042.MP4 | grep -m 5 -E 'ftyp|mdat|moov'
ftyp and mdat present but no moov is the good
outcome: the footage is there and only the index is missing.
The detail of what that means. A file of a few
kilobytes means the footage was never written, and card level recovery software is
the only remaining route.
This runs in your browser. The file is not uploaded, and only the first and last megabyte are read, which is where the markers that decide the answer live. Works on any computer, including Windows, even though the app itself is Mac only.
This checker has its own page at cinesalve.honorboxx.workers.dev/check — easier to pass to someone else who needs it.
The index cannot be copied from another clip. It holds the exact byte position and size of every frame in your recording, so it has to be reconstructed by reading the raw footage and working out where each frame begins, using a healthy clip from the same drone to learn how that camera writes.
untrunc is free and open source and does exactly this, if you are willing to compile a command line tool and hand it a reference file. Try it before paying anybody. If it will not build on your Mac, these are the errors and what they mean.
No other clip from that camera? Record one now. A few seconds at the same settings is enough. The damaged file no longer states its own codec settings, so they have to be read from a working recording, which is why every tool that can do this asks for one.
A Mac app that does the same job. Drop in the clip that will not open plus any clip from the same drone that does, and it rebuilds the index so the file plays again. On a DJI Mavic 3 Pro shooting 4K it recovered all 722 frames, each at the exact byte offset and size the drone originally wrote. Nothing is uploaded; it runs entirely on your Mac. $69 once.
It is measured against a real DJI Mavic 3 Pro recording, 4K at 59.94fps, straight off the drone. Every recovered frame is compared against the original by byte position and size:
| Real DJI footage | Frames recovered | Exact |
|---|---|---|
| Mavic 3 Pro, 4K 59.94fps, cut mid‑flight | 722 / 722 | 100% |
That recording has no audio track, so nothing is claimed about DJI sound yet. It also carries two DJI data tracks interleaved between the pictures, which is exactly what defeated the first attempt: those blocks produce byte patterns that read as frames. Other DJI models have not been through the suite, and a clip from one is genuinely welcome.
A damaged DJI clip is genuinely the most useful thing anyone could send right now: it goes into the test suite and the fix ships for everyone. cinesalve@proton.me (or the contact form), with the drone model and recording mode. You will get an honest answer about whether it can be recovered, including when the answer is no, and there is no pitch attached.