A documentary shooter from Berlin contacted us on a Sunday evening, clearly stressed. During a fast card swap between interviews, she had pulled the SD card from her Canon R5 a second too early. The camera had not finished finalizing the last clips.
The problem
On the card, the last recording appeared not as normal MP4 file, but as .DAT file in size 0 KB — Canon’s temporary container that is used while the camera is still writing. The DAT clip had no valid index, no duration metadata, and wouldn’t open in player, Premiere Pro or Canon’s own tools. In total: about 60 minutes of interview that could never be re-shot.
What we did
- Guide the videographer to made a sector-by-sector image of the card before touching anything (we always work on a copy).
- Extract the raw data of the DAT from the image file shared by the videographer.
- Parsed the DAT containers manually to locate the raw H.265 video stream and the separate audio track，recovering frame by frame.
- Remuxed the clip into a standard MP4 container — remuxing, not re-encoding, so nothing was recompressed.
- Sent a free preview of the longest repaired clip to the videographer the next morning.
✓Result
The clip 68GB was fully repaired and delivered as MP4 file — original 4K resolution, original bitrate, audio in perfect sync. Total turnaround: under 20 hours. The client only paid after confirming the preview.
Why does Canon write DAT file?
When a cinema or camera records, it streams data continuously but writes the file index — the “table of contents” a player needs — at the very end of the recording. If power is lost or the card is removed before that final step, you’re left with a stream of video data that is mostly intact but has no readable wrapper. That’s exactly what a DAT file is: the ingredients without the recipe. Sometime it has normal size, but it is 0 KB(0 Bytes) in some cases.
Takeaways if this happens to you
- Stop recording on that card immediately — put it aside and use a different one.
- Don’t try to rename .DAT to .MP4 — the container structure is different, and players will still fail.
- Don’t run free “universal fixers” on unfinalized camera files; they often truncate the stream to the first readable fragment.
- Send us a disk image — unfinalized DAT/RSV/MDT repair is one of our most common jobs.