Action cameras and drones are hard on memory cards in a way ordinary photography isn’t. High bitrates, sustained writes, cold weather, vibration, and batteries that die without warning while the camera is still recording.
The result is a distinctive set of failures — and the most common one looks far worse than it is.
The unfinalized file: the most common problem by far
An MP4 file has an index called the moov atom. It records where every frame sits, the timing, and the codec details. Without it, a player has no idea how to interpret the file.
Most cameras write that index when recording stops. So the sequence goes: you record, the battery dies or the drone loses power or the card is yanked out, and the camera never gets to write the index.
What you’re left with is a file that contains every second of your footage and no table of contents. Players show it as 0:00 long, or refuse it entirely, or report it as corrupt. The file size is right — sometimes gigabytes — which is the giveaway that the video data is all there.
These are repairable. Because the camera writes the same headers every time, the missing index can be rebuilt using a working file from the same camera, same resolution, and same frame rate as a reference. That’s why anyone repairing your file will ask for a good sample clip — it isn’t a formality, it’s the actual method.
So if you have a broken clip from your GoPro: shoot thirty seconds of your ceiling with identical settings, stop the recording properly, and keep that file. It’s the key.
”SD Error” and “No SD”
GoPros throw these when the card can’t be read reliably. Common causes:
Counterfeit or low-grade cards. Enormously common with action cameras, because people buy the cheapest large card they can find. Fakes report a capacity they don’t have — the 0 bytes article covers how that plays out. Sustained 4K recording is exactly the workload that exposes them.
Card too slow for the bitrate. Not corruption so much as the camera giving up mid-write, which then causes corruption. High-bitrate modes need genuinely fast cards, and a card that handles 1080p fine can fail at 5.3K.
File system damage from power loss. Same root cause as the unfinalized file, one level down.
Worn NAND. Action cameras fill and format cards constantly. That’s real write wear.
Cold and moisture. Winter sports and marine use. Condensation inside the housing reaches the card.
Free evaluation. Firm quote before any work begins.
Chaptered files
GoPro splits long recordings into segments — GH011234.MP4, GH021234.MP4, and so on. It’s a holdover from FAT32’s 4 GB file size limit and it still shapes how footage is stored.
Two things follow. First, if one chapter is damaged, the others are usually perfectly fine, so a corrupted recording is often a partial loss rather than a total one. Second, when you recover files from a damaged card, chapters may come back out of order or with new names — check the timestamps before assuming a segment is missing.
What to do
- Stop using the card immediately. Take it out of the camera. Every additional recording risks overwriting what you’re trying to save.
- Don’t let the camera format it. GoPro will offer this whenever it sees a card it doesn’t like. It’s the fastest way to lose the footage.
- Copy the whole card off first if it still reads. Even the broken files. Especially the broken files — a zero-length-appearing 8 GB MP4 is a full recording waiting for its index.
- Save a known-good reference clip from the same camera and settings.
- Note what happened. Battery death mid-record, card pulled hot, crash, water — each points at a different fix.
What I can do with these
Unfinalized MP4s are one of the more satisfying jobs on my bench, because the footage is genuinely all there and the fix is reconstruction rather than salvage. With a good reference clip from the same camera, success rates are high and the result is the complete recording.
Cards with file system damage get imaged and carved — video carving is harder than photo carving because the files are large and fragment more, but sequential action-cam writes help.
Where it gets difficult: dead controllers, counterfeit cards where the data was never actually stored, and footage that was overwritten by continued shooting after the problem appeared.
The bottom line
If your GoPro or drone file is huge but plays as 0:00, it’s almost certainly intact footage missing its index — repairable, and worth not overwriting. Pull the card, decline every offer to format it, and hang onto a good clip from the same camera as a reference.
Got footage that won’t play? Start a case — tell me the camera model, the recording settings, and whether the battery died mid-record. And mention if you can still shoot a reference clip on the same body.