Sony has recently been promoting a CD copy-protection technology but has revealed little about how it works. Now one of its patents may tell us a lot more. It builds on standards for “multi-session” CDs, which were originally designed to let PC users add data to half-full recordable CDs.
Each track is indexed as having a start, middle and end point. Sony’s trick (WO 01/78074) is to press music CDs on which the indexes are jumbled up for all the tracks except the first. A music CD player should read only the first session and will play the entire disc…
