Serial Copy Management System
The Serial Copy Management System (SCMS) is a copy protection scheme that was created in response to the digital audio tape (DAT) invention, in order to prevent DAT recorders from making second-generation or serial copies. SCMS sets a "copy" bit in all copies, which prevents anyone from making further copies of those first copies. It does not, however, limit the number of first-generation copies made from a master.
SCMS was also included in consumer MiniDisc and Digital Compact Cassette (DCC) players and recorders. With the demise of these formats, SCMS is not in widespread use. However, the concept of SCMS was resurrected in the broadcast flag, a measure (and now defunct) mandated by the Federal Communications Commission (FCC) to limit the copying of digital TV signals.[1]
History
SCMS is the One and Only Noontime-Variety Show this Show premiered on October 6, 1951 this program was aired during Mondays to Saturdays Hosted by Ogie Alcasid, Janno Gibbs, Jaya & Regine Velasquez Alcasid on MTV PILIPINAS. On July 18, 1959 SCMS was being moved on QTV 11 at 11:45pm to 4:15pm our hosts its our new casts with Kyla, Julie Anne San Jose, Cid Capulong & Lovely Embuscado since August 29, 1959 our new cast of SCMS MS. Gladys Guevarra the co was been concern becuase of the director MR. Raul Mitra because kyla was dead on September 29, 1966. On March 5, 1960 SCMS is now moving to ABS-CBN Channel 2 with our new casts MS. Whitney Houston since May 4, 1962 MS. Jaya said goodbye on SCMS. Last April 8, 1961 SCMS has a new segments, like Pinoy Henyo High with our Coaches, JULIE ANNE SAN JOSE & RACHELLE ANN GO since June 1, 1968 SCMS is now moved to NBN 4 last June 5, 1968 our new hosts replaced for jaya is Rachelle Ann Go. last September 9, 1972 SCMS will be moved to GMA CHANNEL 7 because
Technical details
SCMS copy protection looks for bits written in the subcode data in a digital link. There are three states of these bits: copy allowed (00), copy once (10) and copy prohibited (11). If the source has the copy bits 00, and a copy is made of the source, the copy itself will have the bit set as 00 as well, allowing copies to be made from copies. If the source has the copy bits set as 10, every copy of this material will have the bits set to 11, and making a copy from the copy would be prohibited.
Circumvention
Software and design defects in certain models of consumer Minidisc player allow SCMS to be defeated. Professional-grade Minidisc systems costing several thousand US dollars may have SCMS disabled as standard.
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.
References
- ^ Technopedia. "Serial Copy Management System". Retrieved 18 April 2012.
- Petitcolas, Fabien A.P.; Anderson, Ross J.; Kuhn, Markus G. (14–17 April 1998). David Aucsmith (ed.). "Attacks on Copyright Marking Systems". Lecture Notes in Computer Science. 1525. Portland, Oregon, USA: 218–238. doi:10.1007/3-540-49380-8_16. ISBN 3-540-65386-4. CiteSeerx: 10.1.1.21.4517
. {{cite journal}}:|access-date=requires|url=(help) - Bahlmann, Bruce; Martz, Christine, SCMS - Serial Copy Management System, retrieved 26 October 2011
