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My Vixia HF R400 produced .DAT file, rather than .MP4. Why did this happen? I can't play it.


I have a Vixia HF R400.  It is configured to produce .MP4 files and, up until now, has always done so.


I last used the Vixia to record about 6 hours of an important business meeting.  The Vixia automatically broke up the recording into 12 files, of about 3.95 GB each (about 33 min each). 


The first 11 files all have .MP4 extensions, but the last file produced has a .DAT extension.  I tried manually changing the file extension from .DAT to .MP4, but it will not play.


Why did my Vixia produce a .DAT file?  What does this mean?


This .DAT file is about 3 GB, and I know it is supposed to be a recording of about the last 25 minutes of the meeting.


Is there some way to recover the recording from the .DAT file?


Thank you!



If you have good confidence that your .dat file may actually be a broken .mp4 file and the video is of importance to you then you may try one of the commercial repair services or tools. I never had any problems with my Canon HF G30 so far, but I've lost footage from my GoPro HD Hero 3s multiple times. I was able to fix the salvaged mp4 files which weren't directly playable.


I used a tool from a small German company Grau GbR They offer a test version that recovers only 50% which should allow you to find out whether the fixer works for you. You feed the software both a broken as well as a correct file. I had good success with GoPro footage, but never had to try Canon footage as my HF G30 so far works rock solid.

Thanks so much for your reply!!  You would think, by now, that someone with Canon would have tried to help me.  I called the Canon USA-help phone number, but all they tried to do was to convince me that it was

i) a useless random data files, or

ii) if it was a useful file, that somehow it was my fault, for not transferring the files from the memory card (and to my computer) through the Canon software.  Instead, I plugged the memory card directly into my computer, and copied off the files.  Do you see anything wrong with my approach?


Anyway, it is indeed a broken .mp4 file.


I know this because, since submitting my post, I found the Grau company you mention, and tried their free 50%-of-footage test.


Their software restored the video, but there still did not seem to be any audio.  Do you know if the lack of audio is just a result of it being a test run?


Without the audio, the video is essentially useless.


I sent an email to Grau, to see if they could specifically support my model Canon camcorder, but they have not replied.  If you happen to have any good contacts, over at the Grau company, I would greatly appreciate it.


Once again, thanks so much for taking the time to post a reply.

I'm not affiliated with Grau in any way, except as an ordinary user of their software. So I can't help out with better business contact. In Germany, a GbR is a special form of privateer company so I would assume that they are a few persons only, maybe even only two. So it may take some time to respond to your query.


In my case I didn't need the audio as I was salvaging underwater footage and down there audio is often useless. I remember that audio was present and salvaged in my case. If I remember correctly then the 50% should include audio if it was salvaged. The test drive is exactly the same as the full version but cuts off half the video, yet always analyzes the full file.


As for transferring files: SD cards are the only way to do this in any sensible way, USB 2 in my eyes is not suitable. The card readers in cams are just as performant as writing video requires. So uploading through USB is slow, slow and cheap integrated USB interface and slow card reader. Otherwise, the cams would be more expensive and most people would start to quarrel. Better use a dedicated card reader.


My impression is that the more expensive the cam the better the card readers and associated electronics. My HF G30 even works with SD cards where most other cams get hiccups. But even then there are reports from people that experience problems. I've learned a lesson from my GoPro Heros as well as from you: if the footage is really important, use two cams and a dedicated audio recorder. At least in our class...


My video workstation is a Linux system and all my household devices with embedded computers run on Linux or some other embedded system. No Windows, no OSX. Free from broken USB drivers. Transferring large video files via USB 2 is a joke. I use fast SD cards well beyond class 10 and an USB 3.0 card reader. This setup works well and is fast. I need the performance as I'm shooting high bitrate video in 25, 35, and 42mbps.





Thanks so much!!

Rather than record with two cameras, a cheaper solution may just be to have a backup recorder for the audio.  In future business meetings, for example, I plan to also have the audio recorder for my iPhone running.