Hi, there, this is a crosspost here/Dumpcast/Assembler, haha.
Hopefully I can clear this up for you without creating more confusion...
The ringcode is a code that can basically be used to identify if the discs are from the same batch (when manufacturing/pressing). If two discs have the same ringcode, they are from the same batch; if they have different ringcodes, they are from different batches.
For data tracks, the MD5 should be the same across all batches. If the MD5 is not the same, then that means we have a different version of the game -- perhaps bugs were patched, or something new was added. This is uncommon with Dreamcast titles (In the USA, for example, I think only Midway titles, like Ready 2 Rumble Boxing, Hydro Thunder, etc. had multiple public builds).
For audio tracks, the MD5 may or may not be the same across all batches, even if the source audio track is the same exact audio. This is because during the manufacturing process, bytes are added to the beginning of the audio tracks, and a different amount is done depending on the factory/batch. This is called the "audio offset." Audio tracks from the same batch/ringcode should all have matching MD5s, but audio tracks from different batches/ringcodes may or may not have different MD5s.
Discs with different audio tracks but the same data tracks are called "ringcode variants" because the contents are practically the same, but bit-by-bit they are technically not. They are always less of a priority to dump because they are not truly unique.
Luckily, all PAL titles have the same offset, so there's no ringcode variants for PAL titles making a 100% complete PAL set pretty obtainable! For NTSC-U and NTSC-J, there are some titles with a dozen or more ringcodes, so we haven't gotten around to dumping all of them just yet--if ever!
So, back to your original question, which tracks do not have matching MD5 sums? The audio tracks, or the data tracks? At the moment, we are aware of at least one
What's Shenmue? ringcode variant, but we only have one dump of it, so it's considered unverified and thus not in our public dat files. So if you wouldn't mind, we'd appreciate you posting the MD5s for your disc in that thread and you could possibly help us verify another variant!
Also, I'm looking forward to the What's Shenmue translation!
