Fix it now
- Drop the file
- Repair runs locally
- Download the result
The Canon EOS R6 and R6 Mark II record video into MP4 files — H.264 for 8-bit and H.265 (HEVC) for 10-bit modes such as C-Log 3 and HDR PQ — at 4K up to 60p (the Mark II adds 4K 120 fps high-frame-rate). When a clip won't play, the encoded data is normally intact on the SD card; what's missing is the moov index the player needs to read it. Drop the file above and the tool checks exactly that, in your browser, and rebuilds the container when the footage is recoverable. (This page is about video — Canon's CR3 raw photos are a different format and out of scope here.)
Overheating, card pulls, and the unfinalized clip
An MP4 stores its frames as they're captured (the mdat) and writes the index (moov) — the sample tables plus the H.264/H.265 configuration — only when recording stops normally. The R6 line has three classic ways to be denied that clean stop:
Thermal shutdown. The original EOS R6 in particular is known for overheating in extended 4K recording; when the camera hits its limit and cuts out mid-take, the current clip is left without its index. A pulled card. Popping the SD card (the R6 has dual UHS-II slots) before the write buffer flushes, or while the access lamp is still lit, truncates the file. A dead battery ends the write instantly. In all three cases you're left with a large .MP4 that a player calls corrupt or opens to nothing.
The reassuring part is that this is the recoverable case: the take you shot up to the moment of failure is sitting in the file as valid H.264 or HEVC data — only the small trailing map is missing.
How the container is rebuilt
When the moov is gone, it can be reconstructed by scanning the surviving mdat and rebuilding the sample tables Canon would have written on a clean stop. For a faithful result the rebuild needs the exact stream configuration — codec (H.264 vs HEVC), resolution, frame rate and the parameter sets — and the best source of those is a healthy clip from the same R6 body in the same recording mode. If you shot other clips that day at the same settings, keep one handy; you'll only be prompted for it if the broken file needs it.
Two honest limits. If the card was pulled so early that only a fragment of the file was flushed, there may be too little data to rebuild — re-copy the whole file from the card first. And a card with genuinely bad sectors can return zeros for parts of a clip; that's lost data, not a container problem, and no software can invent it back.
What this can and can't fix
Can fix
- The clip the R6 was recording when it overheated, lost power, or the card was pulled (unfinalized MP4, missing moov)
- H.264 and H.265 (10-bit C-Log 3 / HDR PQ) clips that copied off the card but won't play
- Container damage: broken index, wrong offsets, zero-length duration
- Files a recovery tool returned unplayable, when the video data itself survived
Can't fix
- Footage never flushed to the card because the write was cut too early (re-copy the full file first)
- Data physically lost to a card with bad sectors (recover the card, then repair)
- CR3 raw photos or other still-image formats (this page is video only)
- Files that read as 0 bytes or mostly zeros
If a repair fails, we tell you why (missing data versus broken structure), and you are never charged for a failed repair.