redump.info Forum

reentrant wrote:I don't know if such rule (valid for CDi) should be applicable to all systems (especially IBM PC)...

This rule is not affecting IBM PC at all.

reentrant wrote:Small suggestion: is it possible to emit some metadata describing mastering error of a sector - some info describing what's faulty and how it was corrected - for the purpose of being able to reverse repair operation (to have a possibility of creating unmodified dump)?

It's possible but I don't think it's useful for general public. Descrambling is lossless operation and you can always restore any sector how you want, especially if descrambling algorithm is consistent and easy to understand.
If you really care about having unmodified dump, preserve .scram, that will never change.

I decided to simply check edc/ecc if sync or mode was irregular. It is nonsense to change behavior depending on CD-i or not.

If mode bit1 is 0 and bit0 is 1, it deems to the mode1 and calc edc/ecc.
If mode bit1 is 1 and bit0 is 0, it deems to the mode2 form1/2 and calc edc/ecc.
If edc/ecc is correct, the sector is unscrambled, otherwise is not unscrambled.

If mode bit1 is 0 and bit0 is 0, it deems to the mode0 and the sector is unscrambled if sync and msf is correct.
If mode bit1 is 1 and bit0 is 1, it deems to unknown and the sector is not unscrambled.

The result would be the same as redumper's test(01..46), perhaps.

sarami wrote:It is nonsense to change behavior depending on CD-i or not.

Good luck and all the best!

By the way, can anyone upload a sector without sync header of a cdi disc? I want to know if it's "mode2 form1" or "mode2 form2" or "mode2 no edc".