Here's in interesting snippet from last month's
PC World magazine ...
Blue-What?
DESPITE RECEIVING considerable press attention, blue-laser DVD is hardly poised to take over from today's DVD technology. Even the most optimistic analysts don't expect blue laser to have more than a minor market impact for at least five years. But the battle is on over whose format will win the hearts and minds of Hollywood—not to mention a boatload of future royalties.
Of numerous combatants, just two formats appear headed for the big showdown: the DVD Forum's HD-DVD, created by Toshiba and NEC, and Sony's Blu-ray, which is supported by practically everyone else. China is going its own way with EVD (Enhanced Versatile Disc), yet another standard, but the impact of EVD in other countries is uncertain.
In comparison to the red-light lasers used in current CD and DVD products, blue-light lasers possess a shorter wavelength—405 nanometers versus red laser's 650 nanometers. That translates into speedier pulses and smaller marks that are positioned closer together, yielding greater capacity and faster speeds. One beneficiary will be HDTV, which offers up to 1125 lines of resolution and up to 19.4-megabits-per-second transfer rates. Two hours of material transmitted at this speed requires just over 19GB of storage, far more than single- or dual-layer discs now offer.
The DVD Forum, NEC, and Toshiba claim that HD-DVD, which increases the capacity of DVD from 4.7GB to 15GB per layer, is easier to implement and could be brought to market more quickly and less expensively because it doesn't necessitate a complete retooling of existing assembly lines. In fact, NEC has already announced production of a dual red/blue laser read/write head (but no accompanying drive) that is backward-compatible.
Nevertheless, since single-layer HD-DVD capacity falls short of the minimum requirement for handling 17.5GB HDTV—as does the 15GB EVD standard--the DVD Forum is accommodating compression schemes besides today's tried-and-true MPEG-2: the MPEG-4-compliant H.264 and Microsoft's Windows Media 9. Both permit compression ratios higher than MPEG-2 at similar quality, but would require the DVD player manufacturers to pay additional royalties.
Sony and others argue that a clean break with older technology will result in greater capacity; Blu-ray offers from 23.3GB to 27GB per layer, easily exceeding HDTV requirements. Not surprisingly, Blu-ray is sticking with MPEG-2, although its creators haven't ruled out using other codecs.
Neither the HD-DVD nor the Blu-ray spec is graven in stone yet. To muddy the spec waters further, MPEG-4 playback is already appearing on some current DVD players such as NextWave's TW-3108 and Technosonic's MP-101. If adopted by other players and recorders, MPEG-4 may become a de facto specification.
The high-definition DVD fight is a minor story for now. The difference in quality between high-res DVD and current DVD is too small to give users a reason to upgrade until HD content becomes more widely available. Few people own TVs capable of showing off the higher resolution. And the new format's copy protection system will be far tougher than the weak one in current DVDs (see
"Copyright Cops Crack Down on DVD").
That said, the first blue-laser product is already on sale—Sony's 23GB-per-layer Professional Disc for Data. At $2996 for an internal SCSI-3 drive and $3300 for an external USB 2.0/SCSI-3 version, it's a business backup option only, and the $45 discs it writes are not compatible with other types of drives. We were unable to obtain one for testing, but its availability suggests that blue-laser DVD will make its debut via data applications and the prosumer video market.
Source:
PC World