Cactus Data Shield
Encyclopedia
Cactus Data Shield is a form of CD/DVD copy protection
for audio compact disc
s developed by Midbar Tech now owned by Macrovision
. It has been used extensively by EMI and BMG and their subsidiaries. CDS relies on basically two components: Erroneous Disc Navigation, and Data Corruption.
As of September 2006, all of Macrovision's CD copy protection products, including CDS, had quietly disappeared from their website. http://www.macrovision.com/ The December 2006 issue of Billboard announced that EMI had decided to abandon Copy Control worldwide.
Reportedly few discs include Macintosh versions of the software, and generally these computers have no problems being able to see an audio and data session is present on the disc.
The second session on the disc causes some CD/DVD players to hang, typically some car players (allegedly using CD-ROM drive mechanisms) and some MP3 capable players that can see but not understand the second data session.
The second session has been circumvented by another method, which is to either place masking tape
around the disc near the edge, or mark a strip next to the edge with permanent marker. Because it is a multi-session disc, this method will hide the second session, leaving only the first audio session visible.
On older Windows operating systems, disabling auto-play either once when loading the disc, or permanently, can stop the software player from launching and may be all that is required to access the audio session for drives that recognise both sessions. Newer versions of Windows since Vista have fixed the auto-run vulnerability thus all the user needs to do is simply choose not to run the software.
A side effect of the second session containing the music in compressed form is that the maximum length of music on a CDS disc is reduced, being approximately 70 minutes. The remaining space is use for the compressed audio (and the player software and other files though these are small by comparison).
In summary the method described detects during mastering when the waveform of the music comes close to being a straight line for at least the size of a "frame" (information on the disc is encoded in blocks or sectors, each sector contains 98 frames of music for a CDDA disc) and marks the frame and replaces it with erroneous data that violates the (T.sub.max according to the IEC 908) in which there is no transition between the high and low data levels (1 to 0 or 0 to 1). This results in a DSV (Digital Sum Value) error on the CD.
Additional data corruption described in the patent includes adding a duplicate entry of the TOC (Table of contents) from the audio session onto the second (data) session. Some older CD drives would only see the second session erroneous values (such as time and track type) and were not able to copy or play these. Another method is to change the start time of the Lead-Out (end of the disc) to an incorrect time in the TOC. Other patent processes include changing the time in the Q channel so it holds, speeds up or flows backwards.
to the user.
What happens with computer drives is very specific to the hardware
and firmware of the drive in question, assuming they have at least seen past the second data session and can play the audio session.
Some older drives simply ignore the subcode and "play" the data frames, resulting in loud audio glitches. Some are overwhelmed by the number of errors needing correction and interpolation, and these drives may then output occasional glitches. Ripping
at the drive's minimum speed can reduce or eliminate this effect.
The majority of new drives can successfully correct and interpolate all missing audio even at maximum ripping speeds.
Compact Disc Digital Audio standards, and they therefore do not bear the Redbook logo. For this reason they should not be referred to as CDDA (Compact Disc Digital Audio).
There are also ethical/legal issues surrounding the selling of discs that won't reliably play in all players, where added errors make the disc more easily affected by accumulated lifetime damage, and where actual audio data has been omitted.
The first ever commercially released CD to utilise copy-protection was "White Lilies Island
" by Natalie Imbruglia
, which used the Cactus Data Shield and was released in November 2001. With only a minor mention of the CDS in the small print of the CD case, the album was the subject of many complaints from consumers who found that they could not play the CD on non-Windows computers, games consoles and some other devices. Cases included the Xbox
repeatedly playing only a small portion of track 1
, while PlayStation 2
users could play track 2
but not track 1. BMG
later provided uncorrupted copies of these CDs to consumers. Only the initial European release was copy-protected.
CD/DVD copy protection
CD/DVD copy protection is a blanket term for various methods of copy protection for CDs and DVDs. Such methods include DRM, CD-checks, Dummy Files, illegal tables of contents, over-sizing or over-burning the CD, physical errors, and bad sectors...
for audio compact disc
Compact Disc
The Compact Disc is an optical disc used to store digital data. It was originally developed to store and playback sound recordings exclusively, but later expanded to encompass data storage , write-once audio and data storage , rewritable media , Video Compact Discs , Super Video Compact Discs ,...
s developed by Midbar Tech now owned by Macrovision
Macrovision
Rovi Corporation is a globally operating, US-based company that provides guidance technology, entertainment data, copy protection, industry standard networking and media management technology for digital entertainment devices and services...
. It has been used extensively by EMI and BMG and their subsidiaries. CDS relies on basically two components: Erroneous Disc Navigation, and Data Corruption.
As of September 2006, all of Macrovision's CD copy protection products, including CDS, had quietly disappeared from their website. http://www.macrovision.com/ The December 2006 issue of Billboard announced that EMI had decided to abandon Copy Control worldwide.
Erroneous Disc Navigation
CDS discs contain an initial audio session, similar to that of an unprotected disc. In addition the disc contains a second (data) session and a software player configured for auto-play with a lower-quality, compressed version of the audio for it to play.Reportedly few discs include Macintosh versions of the software, and generally these computers have no problems being able to see an audio and data session is present on the disc.
The second session on the disc causes some CD/DVD players to hang, typically some car players (allegedly using CD-ROM drive mechanisms) and some MP3 capable players that can see but not understand the second data session.
The second session has been circumvented by another method, which is to either place masking tape
Masking tape
Masking tape is a type of pressure sensitive tape made of a thin and easy-to-tear paper, and an easily released pressure sensitive adhesive. It is available in a variety of widths. It is used mainly in painting, to mask off areas that should not be painted...
around the disc near the edge, or mark a strip next to the edge with permanent marker. Because it is a multi-session disc, this method will hide the second session, leaving only the first audio session visible.
On older Windows operating systems, disabling auto-play either once when loading the disc, or permanently, can stop the software player from launching and may be all that is required to access the audio session for drives that recognise both sessions. Newer versions of Windows since Vista have fixed the auto-run vulnerability thus all the user needs to do is simply choose not to run the software.
A side effect of the second session containing the music in compressed form is that the maximum length of music on a CDS disc is reduced, being approximately 70 minutes. The remaining space is use for the compressed audio (and the player software and other files though these are small by comparison).
Data Corruption
The second aspect of Cactus Data Shield is careful corruption of the audio data, as described in the Midbar patent "Prevention of disk piracy" US patent number 6,425,098. As usual for patents this is freely available on the US Patent Office web site.In summary the method described detects during mastering when the waveform of the music comes close to being a straight line for at least the size of a "frame" (information on the disc is encoded in blocks or sectors, each sector contains 98 frames of music for a CDDA disc) and marks the frame and replaces it with erroneous data that violates the (T.sub.max according to the IEC 908) in which there is no transition between the high and low data levels (1 to 0 or 0 to 1). This results in a DSV (Digital Sum Value) error on the CD.
Additional data corruption described in the patent includes adding a duplicate entry of the TOC (Table of contents) from the audio session onto the second (data) session. Some older CD drives would only see the second session erroneous values (such as time and track type) and were not able to copy or play these. Another method is to change the start time of the Lead-Out (end of the disc) to an incorrect time in the TOC. Other patent processes include changing the time in the Q channel so it holds, speeds up or flows backwards.
Interpretation of Corrupted Data
An old-fashioned CD player reading subcode correctly sees a missing audio frame and interpolates any missing information that it cannot correct using information from neighbouring frames. Because these missing frames occur at points where the waveform was nearly a straight line anyway, this interpolation is very accurate and generally transparentTransparency (computing)
Any change in a computing system, such as new feature or new component, is transparent if the system after change adheres to previous external interface as much as possible while changing its internal behaviour. The purpose is to shield from change all systems on the other end of the interface...
to the user.
What happens with computer drives is very specific to the hardware
Hardware
Hardware is a general term for equipment such as keys, locks, hinges, latches, handles, wire, chains, plumbing supplies, tools, utensils, cutlery and machine parts. Household hardware is typically sold in hardware stores....
and firmware of the drive in question, assuming they have at least seen past the second data session and can play the audio session.
Some older drives simply ignore the subcode and "play" the data frames, resulting in loud audio glitches. Some are overwhelmed by the number of errors needing correction and interpolation, and these drives may then output occasional glitches. Ripping
Ripping
Ripping is the process of copying audio or video content to a hard disk, typically from removable media. The word is used to refer to all forms of media. Despite the name, neither the media nor the data is damaged after extraction....
at the drive's minimum speed can reduce or eliminate this effect.
The majority of new drives can successfully correct and interpolate all missing audio even at maximum ripping speeds.
Impact
The techniques used on Cactus Data Shield discs mean the discs do not conform to the red bookRed Book (audio CD standard)
Red Book is the standard for audio CDs . It is named after one of the Rainbow Books, a series of books that contain the technical specifications for all CD and CD-ROM formats.The first edition of the Red Book was released in 1980 by Philips and Sony; it was adopted by the Digital Audio Disc...
Compact Disc Digital Audio standards, and they therefore do not bear the Redbook logo. For this reason they should not be referred to as CDDA (Compact Disc Digital Audio).
There are also ethical/legal issues surrounding the selling of discs that won't reliably play in all players, where added errors make the disc more easily affected by accumulated lifetime damage, and where actual audio data has been omitted.
The first ever commercially released CD to utilise copy-protection was "White Lilies Island
White Lilies Island
White Lilies Island is the second album by Natalie Imbruglia. It was released in Europe and Australia in late 2001 and in the United States on 5 March 2002. The name of this album comes from the location of Imbruglia's home in Windsor.-Sales:...
" by Natalie Imbruglia
Natalie Imbruglia
Natalie Jane Imbruglia is an Australian singer-songwriter, model and actress. In the early 1990s, Imbruglia was known to audiences as Beth Brennan in the popular Australian soap Neighbours. Three years after leaving the programme, Imbruglia launched a singing career with the international hit,...
, which used the Cactus Data Shield and was released in November 2001. With only a minor mention of the CDS in the small print of the CD case, the album was the subject of many complaints from consumers who found that they could not play the CD on non-Windows computers, games consoles and some other devices. Cases included the Xbox
Xbox
The Xbox is a sixth-generation video game console manufactured by Microsoft. It was released on November 15, 2001 in North America, February 22, 2002 in Japan, and March 14, 2002 in Australia and Europe and is the predecessor to the Xbox 360. It was Microsoft's first foray into the gaming console...
repeatedly playing only a small portion of track 1
That Day
"That Day" is a song by Natalie Imbruglia, released as the first single from her second album White Lilies Island. In Australia, the song reached the top ten, while it peaked at #11 in the UK...
, while PlayStation 2
PlayStation 2
The PlayStation 2 is a sixth-generation video game console manufactured by Sony as part of the PlayStation series. Its development was announced in March 1999 and it was first released on March 4, 2000, in Japan...
users could play track 2
Beauty on the Fire
"Beauty on the Fire" was the third and final single to be released from Australian singer Natalie Imbruglia's second studio album, White Lilies Island. The single charted at #26 in the UK, and #78 in Australia, making it the least successful single from her first two albums...
but not track 1. BMG
BMG
Bertelsmann Music Group, , was a division of Bertelsmann before its completion of sale of the majority of its assets to Japan's Sony Corporation of America on October 1, 2008. It was established in 1987 to combine the music label activities of Bertelsmann...
later provided uncorrupted copies of these CDs to consumers. Only the initial European release was copy-protected.
See also
- Copy ControlCopy ControlCopy Control was the generic name of a copy prevention system, used from 2001 until 2006 on several digital audio disc releases by EMI Group and Sony BMG Music Entertainment in several regions...
- CDS - Cactus Data Shield CDS100/CDS200/CDS300/Totalplay