Key2Audio

key2audio is a copy restriction system for Audio CDs, developed by Sony DADC. The system gained notoriety after it was discovered that one can effectively disable the system by tracing the outer edge of a CD with a felt-tip markerFact|date=October 2008.

The system works by applying a bogus data track onto the disc during glass master manufacturing. Since computers are designed to read data before music, this prevents playback on PC/MAC and thereby prevents ripping as well as ordinary listening using a computer. CD players ignore any non-audio tracks on a disc, and can therefore play the CD unimpeded - Enhanced CDs also take advantage of this factor.

Currently there are two major versions of the key2Audio protection: the original key2Audio, and key2AudioXS.

key2Audio

key2audio products are mostly compatible because the audio part fully complies with the Red Book standard - not a single bit is changed in the audio data stream - however the CD by itself is not Red Book compliant any more and must not have a "Compact Disc" label.

This leads to problems on some CD players. Since optical computer CD/DVD drives are also capable of reading Red Book audio CDs, a lot of player manufacturersFact|date=September 2007 use these CD/DVD ROM drives instead of specialized Audio CD / Video DVD only drives in order to reduce costs.

DVD players and car stereo systems seem to have most problemsFact|date=September 2007 with incompatibilities of key2Audio protected CDs.

A protected CD still achieves a maximum recording time of 77 minutes and supports full ISRC, UPC and CD-Text capabilities.

Early versions of this copy protection were famousFact|date=September 2007 for being easily circumvented with a marker pen, by drawing a concentric circle on the rim of the visible edge of audio data. [http://www.usatoday.com/money/tech/2002-05-20-copyproof-cd.htm]

Technical background

It seems that key2Audio protected disc TOC contains three sessions written on the discFact|date=September 2007. Two of them contain small data tracks, the third one contains a data track and the audio tracks, and is not closed. The regular CD players pick the audio tracks outright, while the computer CD and DVD players get confused by the corrupted TOC information. CD players and drives that do not support multisession discs are immune against this confusionFact|date=September 2007.

It can be worked around by eg. CloneCD or Exact Audio CopyFact|date=September 2007.

key2AudioXS

key2audioXS combines a PC playback and a clone-proof Multimedia session for CD-Extra and Web Links.

The new version of this protection allows the listener the right to play the CD on a PC, and allows controlled burning the audio to CD. This solution allows consumers a limited amount of private copies. The record labels can individually define the burn count. These copies are then also fully protected and offer the same efficiency and compatibility as the original disc.

The audio sessions are being encoded to Windows Media Audio DRM-protected files, so that some portable devices are supported and online distribution prevented.

Furthermore, with key2audioXS the user can now pick and send audio tracks via email. With a usability period defined by the record label, users can share music, facilitating promotion activities for labels.Additionally, some discs feature "n-CD", which lets the user access bonus features, videos, ringtones, lotteries and similar added goodies. The original n-CD is a unique key reserved for just their owners.

For this purpose, the user interface for key2Audio on PC allows for navigation and includes a copying and burning tool, as well as additional content such as bonus pictures and lyrics.

The audio part can hold up to 75 minutes.

External links

* [http://www.key2audio.com/solution.asp key2audioXS website]
* [http://www.cdfreaks.com/reviews/Key2Audio-explained-and-should-we-fear-it- Key2Audio explained and should we fear it?]