Recovered Video Files Are Corrupted

[eniwetok]

I was trying to recover some video files from an SD card that had been moved to my PC where I must have foolishly deleted them. This required a deep scan and though the files all showed to be in perfect condition with no overwritten clusters... none actually play.

 

Any ideas? I'm investigating .mov repair programs... but recovery would be the best option.

 

Thanks!

[eniwetok]

Quick note.... I wasn't as stupid as I thought. I found the missing files on one of my 6 external drives.

 

But it still begs the question why is Recuva saying that these video files are 100% undamaged... and yet none play?

[Nergal]

It's not saying they're undamaged, it's saying they aren't currently overwritten. Usually a recovered video that won't play has lost their header, which the mov repair applications attempt to rebuild

[eniwetok]

It's not saying they're undamaged, it's saying they aren't currently overwritten. Usually a recovered video that won't play has lost their header, which the mov repair applications attempt to rebuild

 

Thanks for responding. Yes, I've seen some repair utilities that want a un-corrupted file shot on the same camera to try and rebuild the corrupted files.

 

But just curious, how can a video file lose its header... part of the original file, without some part of it being over written? How is Recuva not detecting this damage? Recuva has done wonders in saving all others file types.

[Nergal]

Recuva and other programs can only guess; in recuva's case as I understand it, this means are the bits that the MasterFileTable lists for this file currently overwritten. If I understand correctly some bits may have been overwritten at a different time but currently not. My fellow moderator has a better grasp on this (though neither of us are authoritative sources as we are simple users like yourself and do not work for piriform in any significant sense)

[Augeas]

As it's an SD card it's probably FAT32. A deep scan will look at clusters with a corresponding null entry in the FAT (denoting unused). If a recognisable file signature is found then the following clusters are read until a non-null entry is hit in the FAT. If the file is fragmented, as is quite possible for large video files, only the first fragment can be found and recovered. Thus the recovered incomplete file may not be playable.

 

By definition no file found with a deep scan is overwritten, as the FAT entry wouldn't be null. Thus all files found with a deep scan are marked as excellent, whether the content is valid or not.

 

This only applies to those files found with a deep scan, with names as [001234].mov, for example. A deep scan also runs a normal scan, so files with full names will be treated differently.