FX Fraipont wrote:
Darren Harmon wrote:
Hi; Printed on the cover of the soundtrack of Star Wars AOTC CD are the words "will not play on PC/MAC". Well, it runs on mine. Yet another reason for not using Windows:-)
Interesting.
My son has recently bought a CD that supposedly won't play on PC's. His experience is mixed (he uses win98) : it plays with windows media, but not on the player supplied with the cdwriter.
So what sense does it make?
I've had no problems with "copy protected" CDs under linux. My guess is that true "copy protection" is technically impossible. As I understand it, CDs are just a data stream encoded with a Reed-Solomon error-correcting code and the "copy protection" corrupts the code by introducing false errors. There are two types of error: (a) ones that can be corrected, (b) ones that can be detected but not corrected. If there are type (a) errors, then the CD should be copiable, but won't run at full speed. In the worst case it should only be readable at single speed and be highly vulnerable to scratches. If there are type (b) errors, then the software/hardware can either ignore the error or fail. I think some "copy protection" mechanisms use this in the hope that standard CD players will ignore the error but CD recorders will refuse to copy the data. However, different software and hardware can choose what to do. It is perfectly reasonable to design CD recording software that can ignore (or correct by choosing a plausible codeword at minimum Hamming distance) corrupt data. They might do this, for example, because CDs are badly scratched, without anyone accusing the designers of trying to circumvent copy protection. On the other hand, I'm sure many standard CD players would give up. Does anyone know more clearly what's really going on here? What will XCDRoast do with a "badly scratched" CD? JDL