7-Zipping PSP .iso's changes hash values? Verification is welcome.

Discussion in 'PSP - Games & Content' started by jelbo, May 26, 2008.

  1. jelbo
    OP

    Member jelbo Ōkami!

    Joined:
    Sep 12, 2003
    Messages:
    807
    Location:
    Netherlands
    Country:
    Netherlands
    I compressed some .iso's to .cso using UMDGen which works fine. I then 7-zipped the untouched .iso's in .7z files. Weird thing is, is that when I uncompress them and check their hash values (CRC232/MD5), they're different from the original values....

    Take 'Castlevania_Dracula_X_Chronicles_USA_INTERNAL_READNFO_PSP-pSyPSP' for example. Untouched CRC32 value of the .iso (psy-cvdp.iso) is 26316F37. I then compress the .iso with 7-Zip 4.57 and these settings:

    [​IMG]

    When I extract the .iso from the freshly created .7z the CRC32 value of the .iso is DBD39D16. What's gone wrong? I thought file compression with archives like .rar, .zip and .7z was supposed to be lossless? Is there some kind of value or small bit changed that has lead to the hash value change? Afaik that shouldn't be possible. Maybe my HDD (Samsung 500GB SpinPoint HD501LJ), CPU (Athlon 64 X2 4200+) or RAM (2GB OCZ DC Platinum) is broken? Though WinRAR with best settings creates .rar's that leave the .iso's fine (but .rar's are way bigger, and I deleted the original .iso's XD)

    Could someone verify this with any regular PSP .iso? You can check hash values with QuickSFV, HashTab or from within WinRAR (files inside an archive). Maybe 7-Zip is just broken, but it bothers me because I deleted the original .iso's.
     
  2. arctic_flame

    Member arctic_flame GBAtemp ATMEGA8 Fan

    Joined:
    Nov 4, 2006
    Messages:
    2,840
    Location:
    England land
    Country:
    United Kingdom
    7zip does not touch files...
     
  3. fischju

    Member fischju Rehabilitated Jaywalker

    Joined:
    Jan 11, 2008
    Messages:
    1,940
    Country:
    United States
    I don't know about that, but I've seen bad RAM corrupt files that were zipped/unzipped - try WinRAR and see if it does the same thing. (Which it doesn't for me, an 8GB video on 2 DVDs had the same CRC32 coming out as it did going in)
     
  4. jelbo
    OP

    Member jelbo Ōkami!

    Joined:
    Sep 12, 2003
    Messages:
    807
    Location:
    Netherlands
    Country:
    Netherlands
    Yeah, 7-Zip shouldn't touch files. Could someone with a PSP .iso please check by 7-zipping with above settings and check hash values? Saves me several hours of RAM/HDD/CPU testing if results are the same [​IMG]
     
  5. jelbo
    OP

    Member jelbo Ōkami!

    Joined:
    Sep 12, 2003
    Messages:
    807
    Location:
    Netherlands
    Country:
    Netherlands
    Seems like some PC component had a bad day because all the tests I've done afterward did go well. Ah well, at least it didn't hurt to make .sfv/.md5 files to check if things went properly [​IMG]
     

Share This Page