.mp4 & .m4v Files Unreadable Suddenly (VLC, MPLAYERX, HandBrake, MediaInfo)

[jmix93]

Not sure what I've gotten myself into here but I recently transferred a few external hard drives of video files to a NAS & everything seemed fine, was playing, etc... Now some files will not play in VLC on either my MacBook Pro or Windows 8 PC. The files I'm getting errors from seem to be completely random as well.

Sometimes I get the Error in VLC that "No suitable decoder module: VLC does not support the audio or video format "undf"." Sometimes VLC will load without the error but will not be able to play with the length of video set to something crazy like 8hrs 18min or 0:00:00 when the video is just 90minutes.


When just opening the Info in finder:


General:
Kind: MPEG-4 File
Size: 760,083,397 bytes (760.1 MB on disk)
Created: Monday, August 19, 2013 at 11:38am
Modified: Monday, August 19, 2013 at 11: 58am
Permissions: Read & Write


Invisor:
Format: Unknown Format
File size: 760 MB


MediaInfo:
Returns Prompt: "Can't Find Media Information From this File!"



What I've Tried:


Copied off NAS to Computer.
Tried to play in VLC, MPLAYERX (MPLAYERX Just crashes)
Tried to load in Handbrake, Subler, iFFmpeg (All report Unknown, Incorrect, etc. filetype)



Any help would be greatly appreciated!

[Selur]

Seems like at least some headers are broken/missing.
Might be some hdd problem on the NAS,... (may be it has some logs which could provide additional infos,..)

[Baldrick]

Please dont cross post. I removed your other thread

[jmix93]

Sorry for the cross post. Yeah that was my assumption is there any way to correct that data manually?

[Selur]

Depends on the severity of the problem, in theory if only the first headers are corrupted one could fix the problem with a hex editor.
Since you speak of "a few external hard drives of video files" I doubt that manually trying to figure out what the header should look like and manually fixing this, really is an option.
Also without knowing why the problem occurs, accessing the files through the network interface may corrupt them even further.
If the original hdds with the files still exist, I copying them again would definitely be the fastest solution.