Last month I acquired quite a "treasure" of the CD-i library. Link: The Faces of Evil. The disc and case are in beautiful condition, having only a hairline scratch or two. The jewel case clip is even tight, as if the disc was played only once or twice (not surprised 
).
I'm having strange problems dumping this disc, though.
I've dumped it in two of my drives, each came up with four read errors. The dumps match. I thought I'd try to dump this disc with my handy Plextor in D8 with cdtoimg. All sectors match except the four sectors. The Plextor gets some random gibberish in these sectors. I can't even determine the offset of said sectors with px_d8. These sectors are completely unreadable.
So at this point I'm fairly certain that something is wrong with the disc. Again, it is in stunning condition for what it is. I do my usual research and try to acquire an image from the Internet.
The image from the Internet matches, except for the four sectors. Does this mean the image from the Internet is good? I do a little bit of digging around in the image.
The sectors before the "problem sectors" are all pretty identical. 24-bytes of data followed by 2,328 bytes of null, like so:
A single byte difference between sectors that increments by 1, which is what would be expected for sequential empty sectors.
Those 4 error sectors, though, is also where the Internet-sourced image starts to get strange:
The "00 00 20 00 00 00 20 00" sequence changes. The normal header sequence resumes after these problem sectors. The sectors after the problem sectors, however, now have 4 bytes at the end of the sector (my dumps, cdtoimg d8 dump, and internet dump match from here on).
The problem sectors handled by ISOBuster have the normal "00 00 20 00 00 00 20 00" at the beginning, but also have the 4 bytes at the end (which match the non-error sectors at the end). The Internet-sourced problem sectors do not have this four byte sequence at the end.
Because these images are identical except for these four sectors and because the Internet-sourced image has suspicious data in the same sectors, I have reason to believe that these problems are not unique to my disc.
So the question I have is: What now? I have a feeling I'll have to wait for someone else to try to dump their disc for a proper answer. Suppose that there is a problem with these games and the sectors are truly unreadable, how should they be handled? Should I submit this with "Errors: 4" in the meantime with ISOBuster handling the errors?
If anyone is interested, here are copies of the blank sectors at the end of the disc from three sources (matching ISOBuster dumps with errors handled, D8 dump with unhandled error sectors and 120 bytes missing due to offset, and the internet sourced). The blank sectors start at sector 250,647 and continue to the end of the disc at sector 255,924.
