Serial Copy Management System - Circumvention

Circumvention

Software and design defects in certain models of consumer Minidisc player allow SCMS to be defeated. Professional-grade Minidisc systems come with SCMS disabled, but these run at several thousand US dollars.

European electronic hobby magazine Elektor published a construction project in the 1990s. The device, once completed, was designed to be inserted in the digital link between SCMS enabled devices (the article was designed around the optical TOSLINK interface, but it would have been easy to adapt it to the S/PDIF coaxial link). The circuit intercepted the SCMS control bits, (10 and 11) and substituted the 'Copy Allowed' (00) code. Similar functionality is often also included in commercially available bitrate-converters, like the Behringer Ultramatch.

There is another way that SCMS can be defeated, but it requires copying the Table of Contents from a blank disc that already allows copying, to a recorded 'copy disallowed' disc. The method is laborious, and suffers the disadvantage that the track marks and titles are lost in the process.