Re: [linux-audio-user] Reading/playing a "copy protected" CD : Reed-Solomon correction?

Almost a year ago, I wrote a message to the list on how I managed to play a Cactus Data Shield copy protected (mutilated) 'CD' with linux. See below. The link to the original thread: http://www.music.columbia.edu/pipermail/linux-audio-user/2003-July/005211.h… ----------------------------------------------------------------------- Hello, A collegue of mine just bought the new Radio Head CD, Hail To The Thief. As the box says, this CD is "Copy Controlled". Some searching on the web revealed that it's using so called Cactus Data Shield 200 protection, which means deliberate errors on the cd, that most (not all!) CD players deal with correctly, but cd-rom readers don't. So, what if you want to play your "CD" on a computer? Well, the CD also includes a data track, with a MS Windows (yeah..) application. However! This application does not play the CD audio but a compressed format also included on the CD! Another interesting issue is that the fake errors might actually cause problems when some real errors occur on the CD, that normally would have been corrected, but not anymore in combination with the fake errors. Obviously, all this is completely unacceptable, so I advice you to never buy a Copy Controlled CD. If you have bought one, bring it back to the store. They have absolutely no reason not to give you your money back. (From the web: 'Philips controls the CD standard and their spokesman says: "Any changes that put a disc outside the CD standard result in a disc that should no longer be described or marketed as a CD." Philips, because of conformity issues, has warned the record labels that the discs are actually not compact discs at all, and must bear warning labels to inform consumers.'). I'd add that stores should then not be allowed to sell these CD's in a part of the store that says "Compact Discs" Note that I did manage to play the CD with Linux. My very old (>6 years) SCSI cd writer has been able to read the copy protected CD with cdparanoia. but... in the left channel, every 5.8 sec some values are distorted: about 10 groups of 1 to 3 samples in a row get an extreme value (not always the same, but near maximum). I wrote a small application that corrects those distorted values (linear interpolation with the surrounding samples). I assume this information is legal, because it is only to play the cd, not to copy it. Maarten