Your GoPro file will not play

1. Let the camera try. It has a repair function built in.

GoPro cameras carry a recovery feature usually called SOS. Put the original card back into the camera that shot it and power on: if the camera finds a recording it never finished closing, it offers to repair it. GoPro's own community describes it as scanning the card for unfinalised files and repairing them.

It costs nothing and takes a minute, so it is always worth trying first. It also fails often, particularly when the card was removed and put back, or when the file was copied to a computer before the camera saw it again. If SOS does not appear or does not fix it, nothing is lost.

2. Look for the LRV file. Your footage may already be watchable.

Next to every clip, a GoPro writes two companion files: a .THM thumbnail and an .LRV, which is a low resolution proxy of the same recording. The proxy is written separately from the main clip, so it is frequently intact when the big file is not.

Find the .LRV with the matching number, copy it, and rename the copy to .MP4. If it plays, you have your footage. It is low resolution and it is not what you shot, but for a moment you thought was gone entirely it is often enough, and it tells you immediately that the recording really happened.

Note that GoPro chapters long recordings across several files (GH011234.MP4, GH021234.MP4 and so on). Only the chapter that was being written when power was lost is usually damaged. Check the others: they may open perfectly.

3. Work out whether the footage is still in the file

If the clip is a normal size, say two gigabytes rather than zero, the video is almost certainly still inside it. What a camera writes last, when you press stop, is the index that tells a player where each frame lives. Lose power before that and you have a complete recording with no map, which every player refuses.

On a Mac, this tells you which case you are in:

ls -l GH011234.MP4
strings -t d GH011234.MP4 | grep -m 5 -E 'ftyp|mdat|moov'

Seeing ftyp and mdat but no moov is the good outcome: the footage is there and only the index is missing. What that actually means, in detail. A file of a few kilobytes means the camera never wrote the footage at all, and your only remaining route is card level recovery software.

Is your file recoverable? Check it here

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.

4. Rebuild the index

This is where the free options run out. The index cannot be copied from another clip, because it holds the exact byte position and size of every single frame in your recording. It has to be reconstructed by reading the raw recording and working out where each frame begins, using a healthy clip from the same camera to learn how that camera writes.

untrunc is free, open source and does this well if you are comfortable compiling a command line tool and passing it a reference file. GoPro's extra metadata sometimes needs its -s flag. Try it before paying anyone. 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.

Cinesalve

A Mac app that does the same job. The GoPro recordings below carry their own codec configuration, in the H.264 and the HEVC modes alike, so you give it the clip that will not open and nothing else. Every recovered frame lands at the byte offset and size the camera originally wrote, measured that way on HERO5 through HERO8, Karma, Fusion and MAX. Nothing is uploaded and the recovery runs offline. $69 once.

It is measured against footage straight off real GoPro cameras, comparing each recovered frame against the original by byte position and size:

On GoPro footage the sound is not recovered. These cameras write timecode and telemetry into the same block as the picture, and those bytes cannot be told apart from audio confidently enough to place it. Rather than write noise into your recording, Cinesalve returns the video and says so. If the audio matters more than the picture, that is worth knowing before you spend anything.

If none of it works

Send the clip, or just describe it, to cinesalve@proton.me (or the contact form) with the camera model and the recording mode. You will get a straight answer about whether it can be recovered, including when the answer is no. That costs nothing and there is no pitch attached.