Fixing Sandisk V-Mate's MP4 files when interrupted

[Atario]

Hi, all -- long time lurker, first time poster.

I have a new Sandisk V-Mate (which is like a VCR, but it records to memory cards). I have it set to top-quality mode (meaning 640x480, best quality, 30FPS), and end up with .MP4 files. A couple of times now, I have had recordings non-cleanly interrupted one way or another (power outage, etc.). When this happens, I take the card to my computer and see that the file shows as zero bytes, but in the volume properties, the space is occupied. So I go to Tools --> Error Checking --> Check Now... (the GUI CHKDSK), and check "Automatically fix file system errors", and Start. That gives me a recovery file that seems to be a plausible size for the amount of time it recorded. So I rename the file to the original name and copy it to my computer. However, nothing is able to play the file.

I've tried a few different players, including the standby VLC, but no go. I've also tried a few repair tools, but they all seem to want AVIs (and renaming to .AVI doesn't help, so the .MP4 files must be a different kind of container, I surmise). The few MP4-specific tools I've been able to find also give precious little help.

Can anyone point me to a good, robust MP4 repair utility that will fix this? Or can someone tell me how to conduct manual invasive surgery on files like this (up to and including hex-editor fiddling)?

(If needed, I can generate examples of good and bad files and post them tonight...)

Thanks in advance.

[redwudz]

That sounds like you just have a corrupted file and nothing may recover it if it's badly damaged. There are a few memory card recover utilities and you can try one of them, but I suspect you're wasting you time. Most likely the card was being written to when it was shut off, wiping out the file index and probably destroying the files.

You can search for recovery programs with a internet search for ' flash card recovery software '. There are a few freeware ones available to try out and you may find some pay programs with a limited trial offer. Maybe FileScavenger: http://www.quetek.com/prod02.htm

You could also do a forum search here, as that question has come up before. But it usually concerns photos. MP4 files are a lot easier to damage.

And welcome to our forums.

[Atario]

That sounds like you just have a corrupted file and nothing may recover it if it's badly damaged.

I'm thinking the recorder just slowly writes and writes, appending to the file as it goes, and when it finishes, it writes a format-required footer of some sort (or maybe goes back in the file and overwrites something?), but doesn't get the chance to do this when power cuts.

There are a few memory card recover utilities and you can try one of them, but I suspect you're wasting you time. Most likely the card was being written to when it was shut off, wiping out the file index and probably destroying the files.

The fact that CHKDSK, not even having any special flash-recovery powers, still recovers something plausibly-sized says to me that the blocks are all linked in the directory properly, but the file entry never got updated after the append operation (thus zero bytes still marked on the entry).

MP4 files are a lot easier to damage.

So it would seem. I wish they'd picked a bit more fault-tolerant format...

And welcome to our forums.

Thanks. 8)