there were some PSX games for Japan region that would have subheader field modified.
i can't remember all now, but i would mark them having errors in db.
Space Griffon VF-9 is one of those.
it's interesting that Plextor and Lite-On results from IsoBuster (Alcohol, ImgBurn, CloneCD, etc) would not match.
difference is in sectors that have Sync + Header + modified sub-header + everything else set to 0x00
Plextor would not return this modified subheader in such case, but replace it with zeros instead,
so those sectors would look like Mode0.
when trap disc or d8 is used - results would match.
i've made a short sequence of modified sectors to test this further http://www.mediafire.com/?trtzmmmzimn
and results are interesting imho:
ther's only 6 sectors (this violates minimum track length, but i didn't have problems with it)
with 3 different subheader sequences:
2 with 01 02 03 04 - 01 02 03 04
2 with 01 00 02 00 - 01 02 00 00
2 with 01 00 e4 00 - 01 e4 00 00 <| seq. from Space Griffon
recorded it with Alcohol on Lite-On
on Lite-On IsoBuster would in Sector Viewer replace 1st and 2nd sequence with zeros but display 3rd correctly.
on Plextor it would replace 1st and show correctly 2nd and 3rd
(it's strange, because it does not show correctly similar sector from Space Griffon).
but when backup is made from Plextor all 3 sequences are replaced with 0x00 (d8 work correct, however).
also ImgBurn and CDRWin would not display any subheaders in sector viewer on Plextor (so just like backup).
so would such CD (eg. Space Griffon VF-9) be checked multiple times on Plextor (with everything but PerfectRip/CD Tool) -
it would end up in db different from original.
or at least on my PC. maybe it's just my Plextor. it's Premium model.
also - maybe ther's subheader sequences that would return correctly only on d8 or with trap disc.
so would be great if somebody could verify this.
edit:
actually it seems that sector can have data and it will be set to 0x00 as well.
so conditions are: no EDC/ECC, messed up sub-header.
edit:
it's more complex, i've forgot there was modified sub-headers in Imadoki no Vampire: Bloody Bride
there only 4th byte changes, always the same way:
01 08 64 e0 - 01 08 64 f0
and Plextor reads it fine
so last byte doesn't seem to matter