Short answer first
A .DAT file on a Canon camera card is your video — recorded, present, but never finalized into the MP4 your camera and computer expect. You can’t open it with any player or editor, because it isn’t damaged footage; it’s complete footage inside an unfinished container. The fix is container remuxing, which converts the DAT to a fully playable MP4 without re-encoding — as we do routinely. And if your DAT shows 0 bytes, that’s a different (but usually still solvable) situation — explained below.
What a Canon DAT file actually is
When Canon cameras record video, they don’t write the final MP4 directly. The footage streams into a temporary working file — the .DAT container — and only at the very end, during a step called finalization, does the camera wrap that data into a proper MP4 with a complete index (headers, frame table, duration — everything players need to navigate the file).
Think of it as a manuscript: the DAT is all the pages written but not yet bound. The camera “binds” it into an MP4 the moment recording stops cleanly. Finalization takes a moment, which is why the camera shows a brief “processing” or card-blink after you press stop.
DAT files come from across the Canon range — the Cinema line (C70, C300 series) and mirrorless bodies (R5, R6 series, R7) alike. Sony does the same thing with its .RSV files, Panasonic with .MDT — every manufacturer has its own temporary format.
Why DAT files appear — the three common causes
- Battery pulled or died mid-recording — the most common cause. Finalization never runs; the card is left holding the DAT.
- Card removed before the camera finished — that two-second “processing” pause after stop exists precisely to finish the file; pulling the card during it interrupts the bind.
- Camera crash or freeze — a fault mid-recording ends the session the same way a power cut does.
What’s crucial to understand: in all three cases, your footage was already written to the card. The interruption cost you the wrapper, not the content.
How to open a Canon DAT file
You don’t — not directly, and here’s what not to waste time on:
- Renaming .DAT to .MP4 — doesn’t work. The container structures are completely different; players still refuse it.
- Video converters / “universal players” — at best they error out; at worst they re-encode a partial read and hand back a degraded, incomplete file.
- The camera’s own repair option — worth trying, but it’s a quick patch of the index and fails on genuinely unfinalized files. Its failure means nothing about your data.
The correct method is container remuxing: parse the DAT’s internal data, rebuild the MP4 structure around the original video and audio streams, and deliver a file that plays and edits normally — bit-for-bit the camera’s footage, quality untouched, audio in sync. This is a specialist operation on an undocumented internal format; if you have a DAT file, send it over — DAT-to-MP4 conversion is one of our most frequent jobs, with a free preview before you pay.
The 0-byte DAT file — what it means
Now the harder variant. Your card shows a DAT file with a size of 0 bytes. Three very different situations produce this, and they call for different responses:
1. Finalization started but failed — the “orphaned data” case (most common)
The camera began the finalize step, created the final file entry, then died — leaving a 0-byte entry in the file system while the actual footage still sits unindexed in the card’s storage. The 0-byte size is a bookkeeping fiction; the video data usually still physically exists on the card.
The fix: file-level repair is impossible — an empty file entry contains nothing to repair. The recovery must happen at the storage level: imaging the card and extracting the orphaned video data by code analysis, then rebuilding it into a playable file. We’ve done exactly this in this 68 GB case — 0-byte entry, complete footage recovered.
Your part is critical: the moment you see a 0-byte file, stop using the card. No new recordings, no format. The orphaned data survives only until something overwrites it.
2. Recording never actually reached the card
Rarer: if the failure happened early enough — before the camera had written meaningful data — the 0-byte file may reflect reality: there was little or nothing recorded. An honest assessment will tell you which situation you’re in after inspecting the card.
3. Recovery software produced a 0-byte file
If a scan by recovery software generated the 0-byte DAT (rather than the camera), the software simply failed to associate the data with the entry. The original data is typically still on the card — stop retrying with more tools and get the card imaged properly.
DAT file FAQ
- Is a DAT file the same quality as an MP4? — Yes. The DAT holds the identical data the MP4 would have held. Properly remuxed, quality is identical to a normal recording.
- Can I just put the card back in the camera and re-record to “fix” it? — No. New recordings overwrite the unindexed data you’re trying to save. Set the card aside.
- Does a 0-byte DAT mean my video is gone? — Usually not. In the most common scenario the data is still in the card’s storage; only its index entry is empty. It needs storage-level recovery, not file repair.
- Which cameras produce DAT files? — Canon C70, C300 Mark II/III, and R-series bodies are the frequent visitors to our queue; the mechanism spans the lineup.
Preventing DAT files in the first place
- Never pull the battery mid-recording — stop first, always. Battery swaps take ten extra seconds when done correctly.
- Wait for the post-stop “processing” to finish before removing the card or powering down.
- Watch battery level on long takes — finalization is where recordings are most fragile.
- Offload and verify footage the same day — a file you’ve never played is a file you can’t trust yet.
Takeaways
- DAT = complete footage in an unfinished container; remuxing converts it losslessly to MP4.
- Don’t rename, don’t convert, don’t trust a failed camera-repair — go to container-level repair.
- 0-byte DAT usually means orphaned-but-present data; stop using the card and request storage-level recovery.
- One free assessment answers the only question that matters: is your footage in the DAT, or on the card behind it? Contact us here.