Serial Copy Management System
Used by DAT, MiniDisc, and other digital recording systems to control copying and limit the number of copies that can be made from copies.
SCMS prevents the illegal production of multiple generations of digital copies from a copyright-protected original. Making a single copy for personal use by owners of the
recorder is permitted. The SCMS status of an original is indicated by a copy bit which is present on an original CD and is placed on a recording at a frequency of 75 frames per second.For originals which are subject to copyright protection,the copy bit is continuously ‘on’ (high state).For so-called ‘copy free’ discs,to which no copyright restrictions apply,the copy bit is continuously ‘off’ (low state).For an original which has
itself been copied from a copyright-protected original,the copy bit is toggled every 5 frames between ‘on’ and ‘off’ (high and low states).SCMS distinguishes between three
possible copying situations,and provides appropriate copying strategies in each case:
• Copyright-free originals:copy bit continuously ‘off’ (low state).No restrictions on copying.A copy is also recorded with copy bit continuously ‘off’.
• Normal copyright-protected commercial CDs and all analogue originals:copy bit continuously ‘on’ (high state).A single copy is allowed to be made for personal
use only.A copy is recorded with copy bit that toggles every 5 frames between ‘on’ and ‘off’ (high and low states).The copy is an SCMS original.
• SCMS originals,i.e.copies of copyright-protected originals:copy bit toggles every 5 frames between ‘on’ and ‘off’ (high and low states).No further digital copying is allowed.