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New Audio CD Copy Protection May Already Be Cracked Print E-mail
Tuesday, 24 July 2001
The recently-introduced Macrovision ‘SafeAudio’ system for copy-protecting CDs may have already been broken, according to at least one European cracker site.

The new system, which is intended to prevent the copying, or "ripping" of Audio CDs on a computer, allegedly does not affect audio playback on regular CD players, or even on the CD drives of PCs. SafeAudio apparently operates by inserting short bursts of noise into the audio data stream. These "artificial dropouts" are short enough to avoid muting on an audio CD player – instead, the player interpolates, or guesses, what the data should be. However a CD copying program cannot recover data from the "hole" and the copy fails.

That’s the idea, anyway. However, there are several obvious flaws in the concept. Firstly, when an audio CD player interpolates, it makes an educated guess at what the data should have been during the "hole", but that guess may not be accurate, resulting in a potential degradation of the audio quality. This degradation may be audible, despite Macrovision claims to the contrary. Macrovision says that several titles have been available in the US market for a few months, and one has sold over 100,000 copies – and, they say, the rate of returns has been no more than normal. However, the record buyer does not have the benefit of being able to compare the original master with the "protected" version: they may just think it’s badly recorded or mastered.

Another potential flaw occurs at the other end of the process, namely its ability to prevent copying. The audio CD error-correction technique that allows interpolation of missing data for audio playback without dropouts can also be used in disc copying, by taking the digital audio output provided on many computer CD drives and connecting it to the digital input on many sound cards. This limits the copying to real time, but it can still be done, and if the claim that SafeAudio is inaudible was true, then copies made in this way would not suffer audible degradation either, and the copies thus made would themselves be copyable conventionally. And, of course, there is always the fallback of copying in the analog domain, where with good A/D and D/A converters, the quality can be excellent.

There may be other methods of copying, too. Pieces of software downloadable from various cracker sites on the Internet make it possible to make bit-for-bit copies of CDs, and such copying programs should be capable of replicating a SafeAudio encoded disc.

A post on the Dutch "CDFreaks" site called "How to crack the NEW audio CD protection ?" and dated Sunday 22 July, says, "Game Over used our newssubmit to tell us how he managed to rip a CD that is copy protected with the latest audio CD copy protection." The writer notes, "Tried it with ‘groeten uit Salou 4’ [a Dutch copy-protected CD] works perfectly !!!" His technique involved the use of a special Windows VXD file that causes each track on an audio CD to be mounted as a conventional .WAV file. These can then be ripped straight from the disc without going via the user’s hard drive, probably by using a burst copy technique.

It is strongly suggested that the CD, ‘Groeten uit Salou 4’ utilizes the SafeAudio system, although there is another copy-protection technique that was recently introduced in Austria, Sony’s ‘key2audio’. An article in the Dutch newspaper "de Volksrant" on July 20 mentioned in connection with the CD Freaks postings on this topic infers the former (my rough paraphrasing of a relevant extract follows):

"…The audio protection from Macrovision has already been used for several months in the Netherlands. The system is used on several titles, including the latest album, ‘Puur,’ from Volumia. The album is already available in the stores. BMG confirmed that the system is being used without a notice on the CD itself, stating that ‘they didn’t have time to tell the public about the protection.’ The Dutch audio/video industry trade association confirmed that record companies are using copy protection on some new releases. In addition, Sony has started using its own copy-protection technique, ‘key2audio’, on pressings from its Austrian factory. ‘Although these discs are not produced specifically for the Dutch market, it may be possible that units have been shipped to the Netherlands’, Sony commented. But the most important issue raised by these protection techniques is that they violate the Dutch law that gives consumers the right to make one copy for private use..."

The issue of consumers being allowed to make a single copy of a copyrighted work for private use also applies in the US, but it has been noted that while US legislation makes it legal to create such a copy, it does not require the copyright owner to make the copy possible.

The CD Freaks site also refers to other "more recent" copy protection schemes in which additional unreadable data tracks are placed between or after the audio data. These are not "seen" by an audio CD player but they are by computer applications, which then fail trying to copy the faulty data tracks – a technique perhaps similar to the old floppy-disk-based copy protection schemes. These can also be circumvented using free software available on the Net.

Once again, it appears, attempts are being made to foist a copy-protection scheme upon consumers that will stop them making perfectly legal CD copies for personal use, for example, while potentially degrading the audio quality. The idea has been compared, by British consumer audio writer Martin Colloms, to slashing all the paintings in an art gallery to stop people stealing them. And the scheme has already been broken.

It sounds as if the real solution is to put all that money wasted on copy-protection into making the product itself less expensive. As "RDJ134", writing on the CD Freaks site put it, "Hehehe they think they’re so smart with their protection. They lose again… MAKE THE DAMN CDS CHEAPER!!!!"

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