CD's That Don't Play

This article originally appeared on British-Audio.org.uk

The BFA and its members have received calls about newly purchased CDs that will not play, lock up computers or, in some cases, just don't seem to sound as good as they should.  We are saddened that sections of the record industry should treat their customers with so little respect.  We asked the best known industry technology and patent journalist in the UK, Barry Fox to explain the possible background to what we feel are the majority of complaints.

british federation of audio

Dealers and manufacturers are facing angry customers who wonder why their new CD and DVD players will not play some CDs. In many cases this is because the CD has been copy-protected by the record company, often without clear labelling, and with the unhappy side effect that innocent play is sometimes prevented.

In the USA, where aggrieved parties can co-operate in a "class action", consumers are now suing the five major record companies (BMG, EMI, Sony, Universal and Warner). The action, started in California, demands the removal of copy-protected CDs from the market or clear labelling to warn they are not genuine Red Book CDs, with damages to pay for the repair of computers which have crashed or refused to eject protected discs. The action - and more expected to follow - may extend to dealers selling the discs, replicators pressing them and the companies supplying the copy-protection technology.

The US action complains that the music industry is already collecting royalty taxes on digital recorders and blank media under the 1992 Audio Home Recording Act, as compensation for the home copying which protected discs try to prevent (all a part of the Parental Advisory fiasco). Although British law is unusual in that it does not allow any home copying of music for personal use, and there is thus no royalty scheme, other countries in Europe (e.g. Germany) do have a tax. So the record companies may face legal action in Europe.

The basic patents on CD audio are now dead, so Philips cannot enforce the Red Book licence; indeed Sony, co-owner of the patent pool, has its own protection system (called Key2audio). Philips could still enforce its rights on the CD logo trademark, but some protected discs carefully avoid using it.

compact disc digital audio

The situation is fluid; legal actions take time to resolve, and can be stalled by appeal procedures, so the record companies currently remain free to release copy-protected discs - and they have made clear their intention to increase the use of protection. Audio dealers urgently need clear advice to offer customers who blame their hardware when CDs mysteriously refuse to play, or MP3 players refuse to rip discs, or hard disc servers are unable to store some CDs.

The record companies have been very evasive about their protection technology. So it is up to the audio industry to help itself. What follows is a rundown on the raw facts, gleaned from published patents and practical tests on discs on sale. This rundown will be updated as dealers share new information.

Macrovision is already well known for its video copy protection, as used on VHS tapes, DVDs and Pay TV channels. The company is now actively promoting SafeAudio which introduces uncorrectable digital errors into the music bitstream. This drives a consumer CD audio player or PC ROM drive into interpolation or guesswork. So the disc plays Red Book music on CD player or a PC, but will not copy on a PC.

Macrovision assures that the bitstream errors can be intelligently positioned so that interpolation causes no audible effects, and argues that the failure of consumers to complain about the performance of unlabelled discs already sold as part of stealth testing proves this. The fallacy is obvious; because discs are unlabelled, Macrovision can only register complaints if high street record stores can be relied on to log and relay customer's queries on subtleties of audio quality.

Following criticism of this approach, Macrovision is now opening up to suggestions that the inaudibility claim should be put to the test by independent listening panels using only the best headphones with the highest fidelity.

Macrovision also has another system, called AudioLock which can stop people using a PC burner by preventing all playback on PCs and CD and DVD players that use ROM drives. Deliberate errors are added to the Table of Contents (e.g. to say the lead-out comes immediately after the lead-in or wrongly describing music as computer data). These errors stop CD-ROM drives dead in their tracks, but music CD players usually just go on playing until the disc ends.

Variants of this system alter the timecode information in the P and Q "subcode" data channels. Once it has started to play a track, a music player should ignore the bad code (albeit displaying incorrect time), but a ROM drive keeps on checking the code, tries in vain to correct the errors and shuts down.

cd q-subcode group

After toe in the water tests (e.g. with Nsync's Celebrity album in Germany) the first mass market release of a copy-protected CD was by BMG in Europe, with Natalie Imbruglia's White Lilies Island. Five's Greatest Hits followed soon after. Both used Cactus Data Shield, from Midbar in Israel. Neither carried a warning label. The telltale sign of a Cactus disc is a narrow clear dividing band between inner and outer areas of the playing area.

The CD is a "multi-session" disc of the type routinely used to let audio and computer data share the same disc; the data and audio are recorded at physically different positions, and in the case of Cactus discs the sessions are separated by a visible dividing band.

A ROM drive goes first to the data area. On a Cactus disc the data is music in heavily compressed form, encrypted so that a PC can only read it only with the help of proprietary player software. This is also stored on the disc, automatically loading into the PC and running itself instead of the usual PC software like Windows Media Player. The encrypted music cannot be copied by normal PC software. But innocent listeners get only heavily compressed sound, played by an alien software player. Red Book consumer CD players should ignore the data track and play the ordinary CD music. But any player with a ROM drive may refuse to play all or some tracks.

cactus media player

Sony's Key2audio system comes from the DADC disc pressing plant in Austria. Celine Dion's "A New Day Has Come", Shakira's "Laundry Service" and "J To Tha L-O!" by Jennifer Lopez all use the system, and the discs carry a bold warning that they will not play on a PC.

The Key2audio disc is a multisession disc, with several sessions each having lead-in, data and lead-out areas (but without visible dividing bands between them). The first session is normal and contains Red Book audio, but the lead-ins to the later sessions contain deliberately incorrect information. This mis-information points to other sessions, and these sessions contain deliberately incorrect timing and sync data.

An audio player should play only the first session and ignore all the other sessions, so never see the bad data they contain. But a ROM drive will look at the later sessions and become confused by the bad content. So PC play - and with it PC copying - is prevented. But the corruption can crash some computers, prevent re-boot and physically lock the disc inside the drive; it can also prevent normal playback on consumer players which happen to use ROM drives. This is what prompted the legal action in the USA.

While the music industry continues to insist that copy-protection causes few problems, there is one clear message that dealers should pass on to customers who complain that discs won't play: complain to the record shop and ask for a refund. That is the one and only sure way to ensure that a complaint is fed back to the record company.