Could someone explain PAR2 files to me like I'm a 10 year old?

[BrokenVisage]

I know you need QuickPar to properly use them, but how in QuickPar do you use PAR2 files to restore RAR's and crap? Honestly I read a couple pages about it and I'm still lost, maybe I just don't understand the concept.

 

[icelazer]

http://en.wikipedia.org/wiki/Par_Files

That is the basic premise. Let's say you have an 8 bit number: 01001101 for example.
A basic parity concept would be to add up the number of '1' bits mod 2. There are 4 '1' bits, mod 2 is 0. The parity bit would be 0 for that number. If any single bit were to change for some reason (error or otherwise) lets say 01001001 the parity of this byte is 1 since 3 mod 2 is 1. Since the parity bits would not match for any odd number of errors, we would know that an error exists. This will not allow corrections to the errors, however. Search for hamming codes on more information on reconstruction. As far as whatever specific program to rebuild the files, I always prefer winrar.

 

[crizzar]

par2's are wild cards to repair broken downloads

par2 sets are uniquely created to each set of rar files, when you run quickpar, check the option to automatically repair. What it does is scan the rar files for integrity and for the ones that are missing blocks, it'll automatically repair it so you can get your image unrarred

It's modern-day magic

 

[0roo0roo]

when you open a par with quickpar or whatever it automatically checks the integrity of the rar's or whatever files types it was associated with and created from. if it finds errors and has enough parity data it reconstructs the files. par isn't rar only. you can make par/par2 for anything you want another degree of backup safety for.

 

[skace]

Put the pars in the same directory as the files they were created for (IE: A set of 40 RARs).

Run any of the par files and it opens up the program associated with it (IE: Quickpar).

It starts looking for the files expected to be with the PAR and scans them to ensure they are complete.

It then uses the number of PAR files to repair a given number bad blocks with the scanned files.

If you do not have enough PAR files, you check to see if there were some you did not download. If there arn't, you try to re-grab more files from the original RAR set until you can repair the leftovers.