The CD Writer - Ultra-Speed CD Recording: When is Enough, Enough?
July 2001 |
From the beginning, CD-R has consistently exceeded expectation in reliability, compatibility, stability, cost, popularity, and performance. Even recently, 8X writing was considered the absolute speed limit, but soon, 24X recorders will be hitting the street with still faster products in development. But be it CPU speed, hard drive capacity, or CD-ROM performance, there comes a time when further advances make little sense for most of us. Such is the case with ultra-speed CD recording.
An important point to remember in the race for higher recording speeds is that the law of diminishing returns applies after 8X. In the old days, performance advances translated into meaningful productivity gains. Writing a full disc at 2X took roughly 38 minutes, but at 8X, writing is done in only a quarter of that time. For 12X, 16X, and 24X recording, which take roughly six, five, and four minutes respectively, are the times saved really that important for most people?
Perhaps the most misunderstood dimension of ultra-speed recording is that increases in writing performance are only wholly realized when producing full discs. By way of technical explanation, Compact Discs were originally designed to operate using a Constant Linear Velocity (CLV) scheme to maintain uniform scanning velocity of the optical head across the entire surface of the disc. The disc's rotation speed slows as the optical head reads or writes from the inner diameter to the outer diameter. At 1X CLV speed, the disc is spun at 500RPM when the optical head is operating at its inner diameter and slows to 200RPM at its outer diameter. So when recording at 16X CLV, for example, a disc spins between 8,000 and 3,200RPM from its inner to outer diameter.
Operating at such high velocities places tremendous physical expectations on recorders and media and severely tests the limits of what's possible with low-cost product design. Consequently, manufacturers use several different techniques to keep disc rotational speed manageable while still achieving higher recording speeds. One of these is Partial Constant Angular Velocity (PCAV), which spins the disc at a lower fixed RPM while the optical head is writing near the inner diameter and then shifts to a CLV mode part way out of the disc. Yamaha's 16X recorder, for example, accelerates from 12x to 16x speed over the first 125MB, but then maintains 16x writing for the remainder of the disc.
Another method used to permit higher-speed recording is Zone Constant Linear Velocity (ZCLV) which writes the disc in a CLV mode, but instead of maintaining a uniform writing speed throughout employs different fixed writing speeds while operating in discrete regions of the disc. Sanyo's 24X unit writes the first part of the disc at 16X, the second at 20X, and the last at 24X speed. Most data CDs contain less than 300MB, so there's little practical gain in using ultra-speed recorders. In the case of 50MB business cards, ultra-speed recorders are simply left idling.
Without a doubt, one of the most popular consumer uses for CD-R is personal audio, where entire music CDs are copied or compilation discs created. The most common and fastest method for accomplishing these tasks is by using a separate CD-ROM drive as the master recording source and directly copying audio tracks disc-to-disc. Duplicating audio on-the-fly at 8X and lower recording speeds is an accepted and reliable process but, thanks to slow or unreliable Digital Audio Extraction (DAE) performance, changing to 12X and higher results in many CD-ROM drives having trouble keeping up. The hard reality is that the typical DAE speed of the installed base of drives is simply insufficient to sate the demanding appetites of ultra-speed recorders. Even those drives able to keep pace can't do so if the source discs have been damaged by handling or manufactured poorly to begin with.
Several other issues, such as fragmented hard drives, improperly configured IDE channels, and network interference also conspire against ultra-speed operation. New technologies such as Sanyo's BURN-Proof and Ricoh's JustLink, Flex-SS, and JustSpeed insulate users from system or media deficiencies. Therefore, they may give the illusion of ultra-speed recording without actually achieving it.
Ultra-speed writing membership may have its privileges, but it also has costs. Not only do the fastest recorders cost more, but compatible blank media is also more expensive. Not all discs will record at 16X and even fewer at 24X speed, so users can expect to pay a premium to achieve potentially higher performance.
Beyond the conventional consumer and business applications, duplication and other professional users of CD-R benefit little from ultra-speed recorders. In addition to the previously stated issues, the throughput of automated CD production systems equipped with multiple recorders and in-line printers is ultimately governed by robotic disc handling and labeling, which have their own time considerations.
Just as with CD and DVD-ROM drive performance, advances in CD recording speed are being driven by manufacturers' never-ending quest to differentiate their products not to satisfy consumer needs or enable new applications. The market is now at the point where manufacturers should look beyond speed and offer additional useful capabilities. CD-ROM drives gave way to CD-R/RW recorders, so perhaps its time for CD-R/RW recorders to yield to hybrid products for video and other new applications by writing not only CD-R/RW discs, but DVD-R/RW/+RW media as well.
Hugh Bennett (firstname.lastname@example.org) is an EMedia contributing editor and columnist for The CD Writer, is president of Forget Me Not Information Systems (www.forgetmenot.on.ca), a reseller, systems integrator, and industry consultant based in London, Ontario, Canada.
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