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Sega CD 32X questions
Posted: Sat Mar 01, 2008 3:54 pm
by pepsidrinker
I bought one of them today and am in the process of dumping it. Do you think I should put it under the mega-cd section with 32X in the version or edition or what? There is only 5 so I don't think it needs it's own part of the database what you guys think?
Just to make sure also I got the offset correct...
63 lines with the d8 method
63 X 16 = 1008 /4 = 252
252 - 1176 = -924 - +30 = -954 (write offset)
Re: Sega CD 32X questions
Posted: Sat Mar 01, 2008 5:54 pm
by Dremora
pepsidrinker wrote:63 lines with the d8 method
63 X 16 = 1008 /4 = 252
252 - 1176 = -924 - +30 = -954 (write offset)
Is +1176 your drive reading offset? What's +30?
Re: Sega CD 32X questions
Posted: Sat Mar 01, 2008 6:01 pm
by pepsidrinker
+30 is my drives read offset.. I was following the directions for the D8 method.
This time there is 2236 bytes before the sync/header, or 513 samples.
However, this time the sync/header is slightly different from our previous example (00FFFFFFFFFFFFFFFFFFFF00018202...).
This difference in the header (18202 instead of 18200) indicates that the data is read from sector 2 instead of sector 0 (see post below for more info).
A full sector is 2352 bytes or 588 samples of data, so the difference is 2*588 samples.
Combined read+write offset = 513 - (2*588) = -617. Because the drive that we used is +30 read offset, the factory write offset is -647.
I guess I don't understand the math... how in the example does it become -617?
2 X 588 = 1176 right
so 513 - 1176 would = -663 right? What am I missing?
Re: Sega CD 32X questions
Posted: Sat Mar 01, 2008 6:39 pm
by gigadeath
I think Dremora is asking that because in both EAC and PerfectRip logs you posted above I see a +252 offset correction. Why that? Using your calcs the write offset is -954, and if combined offset is -924, you should use that to dump. +252 is completely wrong.
Moreover are you sure you have to subtract -1176 for this disc? The part of the guide you cited is only an example, you don't have to always subtract 2 sectors to get the offset. What number do you get after the sync? Is it really 018202? Or is it 18200? SegaCD discs shouldn't have big negative offsets.
Re: Sega CD 32X questions
Posted: Sat Mar 01, 2008 6:47 pm
by gigadeath
Can you post here the D8 info?
Re: Sega CD 32X questions
Posted: Sat Mar 01, 2008 6:52 pm
by pepsidrinker
gigadeath wrote:I think Dremora is asking that because in both EAC and PerfectRip logs you posted above I see a +252 offset correction. Why that? Using your calcs the write offset is -954, and if combined offset is -924, you should use that to dump. +252 is completely wrong.
Moreover are you sure you have to subtract -1176 for this disc? The part of the guide you cited is only an example, you don't have to always subtract 2 sectors to get the offset. What number do you get after the sync? Is it really 018202? Or is it 18200? SegaCD discs shouldn't have big negative offsets.
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There is 63 lines...
Re: Sega CD 32X questions
Posted: Sat Mar 01, 2008 7:43 pm
by gigadeath
Yes the combined offset is -924. That's the number to use (in PerfectRip it's +924)
EAC doesn't detect track02 pregap, so the resulting file has should have no pregap.
Try manually adding a 2.00 pregap to EAC's track02, and see if it matches PerfectRip's track02 in size and CRC.
Re: Sega CD 32X questions
Posted: Sat Mar 01, 2008 7:44 pm
by pepsidrinker
I did add the pregap. it matches in size but not crc.. I can upload with the new offset 2nd track audio if someone wants to look at it.
Re: Sega CD 32X questions
Posted: Sat Mar 01, 2008 7:46 pm
by gigadeath
Yes if you can
What about data track? Do PerfectRip's and IsoBuster's match?
Re: Sega CD 32X questions
Posted: Sat Mar 01, 2008 7:48 pm
by pepsidrinker
Yes, they match.