Copy Control
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Copy Control is the name of a copy protection system used on recent EMI digital audio disc releases in some regions. While basically intended as a means of copy-protecting compact discs, Copy Control discs cannot properly be referred to as CDs as the system introduces intentionally corrupted data, making the discs non-compliant with the Red Book standard for audio CDs. The system is intended to prevent digital audio extraction ("ripping") from the protected discs, and thus limit the file sharing of ripped music. The techniques used are:
- Multisession (Blue Book) information is included which effectively hides the audio tracks from most CD-ROM drives;
- Error-correction codes for the audio data are corrupted, which may introduce audible errors to ripped copies.
- The data area of the disc usually includes DRM-restricted copies of the audio content, which are compatible with some major operating systems such as Microsoft Windows.
Background
The Copy Control system was devised in response to the file sharing and casual CD copying that has become commonplace in recent years, allegedly causing the music industry significant lost revenues. Neither issue was particularly relevant when the CD standard was introduced in the early 1980s, and thus, unlike the more recent DVDs, the CD standard specifies no inherent form of copy protection or other digital rights management. Copy Control is one of a number of attempts to apply copy protection on top of the CD standard, but since it is merely a modification of the already unrestricted standard which must still yield usable results in most CD players, the efficiency of the system varies significantly.
As the Copy Control discs do not conform to the requirements of the CD standard, they are not labelled with the CDDA logo, which is trademarked by Philips and Sony. A Copy Control "CD" which would not play in a woman's car CD player, was deemed "defective" in a French 2003 lawsuit, and any recent Copy Control releases carry visible Copy Control notices stating merely compatibility with CDs and the possibility of playback problems "on some equipment, for example car CD players". Nevertheless, the discs are frequently incorrectly referred to as CDs or "copy-protected CDs" in music stores and in colloquial language.
Circumvention
A Copy Control disc will appear as a mixed-mode disc, with audio and data content. Under Windows, inserting the disc will usually autorun an audio player utility, which plays the DRM-protected audio files provided. (This can be temporarily disabled by holding down the shift key while inserting the disc, or by disabling autorun altogether.)The ability to extract the CD-Audio tracks is otherwise largely dependent on the disc drive used. The first obstacle is the 'fake' Table of Contents (ToC), which is intended to mask the audio tracks from CD-ROM drives. On the other hand, CD-R/RW drives, and similar, can usually access all session data on a disc, and thus can properly read the audio segment. (It has been reported that the fake ToC may also be bypassed by obscuring the outer 2-4mm of the disc with a temporary felt-tip marker. This method, however, may no longer be effective due to advances in Copy Control technology.)
The other major obstacle is the corrupted error-correction data. Again, the effect of this is dependent on the disc drive; some drives will be able to read the data without problems, but others will produce audio files with loud pops every few seconds. (A related problem is that copy-controlled discs will probably not be as resistant to scratching.)
Copy Control also does not prevent copying a disc by recording it as audio through a computer's sound card, which only causes a slight degradation in audio quality, or none in the case where a digital link is used. More substantial is the loss in recording speed. This poses a major problem to the music industry, due to the fact that many "pirates" illegally rip protected CD audio in this way.
Usually a CD-R/RW drive will play the disc but with occasional stops (about every 10 seconds) and DVD-R/RW drives will be able to read the data without problems and can be ripped straight to the PC. CD-ROM or DVD-ROM drives in a computer will usually refuse to play the data except in the provided player.
Systems other than Windows, however, can easily play Copy Control discs, with the disc appearing as two entities, "Audio CD" and whatever the data portion of the disc was named in manufacture. As the bundled players are usually Windows Proprietary, and, similarly, the auto-launchers are designed for Windows, there is little that can be done to stop a non-Windows user from ripping a Copy Control disc (though, arguably, the process may take longer).
In Mac OS X, Copy Control discs are easily accessed through iTunes and Quicktime (When a CDDA track is dragged to a folder other than the CD, Quicktime automatically converts it to AIFF, which is a lossless PCM format). Though some Copy Control discs do have Mac OS software, this is becoming less common.
Content on the CD extra
CDS-100 or CDS-200
A player and a media file database(A copy of the audio contents in Windows Media). The player will only play the audio contents in the media file database.
CDS-300
A player and the anti-copy program only. The player can ignore the anti-copy program to read the audio tracks. The player allow users to play the tracks, rip the audio tracks as DRM WMA files and burn CD for 3 times (The player will rip the CD as 320kbps WMA files, then burn the audio on a CD-R, notice that the volume is lower and the quality is worse on the burned CD)
See also
- Analog hole
- Cactus Data Shield
- Copy protection for audio CDs
- — overview of Copy Control releases
- MediaMax CD-3
- Key2Audio
- Extended Copy Protection
External links
- [EMI]
- * [Copy Control information]
- * [Disc Playback Problems] - Questions and Answers
- [Consumer petition against Copy Control]
- [IFPI Press Release] - IFPI issues labeling guidelines for Copy Control discs
- [Evaluating New Copy-Prevention Techniques for Audio CDs] (PDF format), by J. Alex Halderman
- [padawan.info: Protected CD judged abusive in France]
- [Guide to Copying Copy-Protected Music discs]
- [EMI Music & Sony/BMG Anti-Copy Control Information]
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