Topic: Cyclic Redundancy Check

[GillE]

I've been trying to copy some old videos from DVDs I have recorded but sometimes I get an error message, "Cannot copy XXX.vob:data error (cyclic redundancy check)".  I presume this means that part of the DVD has been corrupted.

Is it possible to salvage the file, or at least a part of it?

Gill

[Simon]

There are plenty of technical resources on the Web that discuss cyclic redundancy checks (CRCs). Most times you won't need to worry about this technobabble. That is, until one it day it suddenly appears and you think - what the hell does that mean? In simple terms, a CRC is bit of mathematics used to ensure that your data is OK when being transfered. It's a checking procedure that quickly identifies when data has been damaged. If you get this message, it means that the file being read by your PC or software is corrupted. However, it does not mean all the data is lost forever. When data is transfered, it is usually in small blocks and each block is given a CRC value. If something goes wrong with the data between the time it leaves the source and arrives at its destination, the CRC sent at the source will no longer match the one that is calculated when the data arrives - this is when the cyclic redundancy check error will appear.

Oh, by the way, in case you thought I was being very clever, I got that from here, where there is also further info, and suggested remedies, Gill. 

[Lona]

You could always try converting the files to a different format, Gill, to see if that works.

[daveeb]

Gill two things to check as it may not be corrupted data.

firstly clean the disc with a slightly damp fibre free cloth (from the inner spindle hole outwards like the spokes of a wheel, not in a circular motion). Leave the disc to completely drive first.

secondly it could be that the power of the disc drive has decreased slightly and it just can't read some less reflective discs any more.  If you have access to another drive i'd try that otherwise it might be time to replace the drive.  They're very cheap these days 

[GillE]

Thanks for the advice.  I've tried all the suggestions over the weekend but, sadly, it looks as if I'm paying the real price of using cheap media in the past  .  Some of these DVDRs used to be okay but it looks as if they've deteriorated with time, despite being stored in jewel cases at an ambient temperature.

Gill