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CD anti-piracy system can nuke hi-fi kit

Sony is already testing it

New Scientist later retracted its report
"that an anti-piracy technology, called Cactus, from Midbar Tech of Tel Aviv, could damage hi-fis and loudspeakers (New Scientist, 4 August 2001, p19). This is incorrect". You can read the correction in full here.

Sony's Music Entertainment division has been testing an anti-piracy technology that at best renders illegally copied CDs unlistenable and at worse blows listeners' speakers.

The anti-piracy system, called Cactus Data Shield, was developed by Israeli technology company Midbar Tech. Research conducted by New Scientist magazine and reported in this week's issue shows how Cactus works. Like Macrovision's SafeAudio, Cactus adds noise to the music data stored on the CD. Unlike SafeAudio, Cactus flags the noise as control information. On playback, this is ignored, but on duplication - even with consumer CD-to-CD systems, which are not disabled by SafeAudio - the noise disrupts the copier's error correction system.

The result: a CD-R full of noise, not music. Worse, the generated waveform is of kind to which hi-fi and loudspeaker circuitry is particularly sensitive. Play the noise-filled disc back at too high a volume and - bang - your speakers are toast.

Frighteningly, the ability to damage equipment can be effectively switched on or off by the CD mastering company by changing the characteristics of the noise and thus the soundwave generated by players' error correction systems.

Sony's Cactus tests, carried out, claims New Scientist, in Slovakia and the Czech Republic were not set to nuke hi-fi equipment, but they easily could have been it seems.

It will make an interesting test case when a punter sues Sony for blowing up their loudspeakers after playing an allegedly pirate CD, particularly if the music industry and consumer electronics companies haven't issued warnings that pirate CDs can seriously damage your equipment.

Midbar's technique, like Macrovision's SafeAudio, also plays fast and loose with listeners' rights to make copies of discs for their own personal use. Both companies claim the inserted noise does not affect the listening experience.

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