HD-DVD, approved by the DVD Forum, is blue laser-based. The other format, Blu-ray, is based on blue/violet lasers and supported by Sony, Matsushita, Thomson, Philips, Pioneer (some of them Forum members who developed the format outside the Forum). Dell, Hewlett-Packard, and LG Electronics offered up products based on Blu-ray technology at the 2004 Consumer Electronics Show in January in Las Vegas. (Sony has been shipping a Blu-ray drive in Japan since February 2003.) Meanwhile, Toshiba and NEC demo'd HD-DVD players. Both new formats are still in development, but pilot lines already exist.
At the IRMA Management Summit in December, Dominick Dalla Verde, senior director of preproduction at the Cinram (formerly WAMO) plant in Olyphant, Pennsylvania, did a presentation about the two formats. His data was somewhat sketchy, and Cinram declined a request to provide further details. Sony, on the other hand, was very forthcoming with details about Blu-ray. What is evident is the formats are very different from each other, and therefore difficult to compare. HD-DVD is more like an upgraded DVD, whereas Blu-ray is on a different course altogether. HD-DVD seems to have momentum in the U.S., but Blu-ray has a lot of support in Japan.
Mike Fidler, senior vice president, of Blu-ray Disc Group, Sony Corporation of America, says the next format may be the last packaged media. "Having Panasonic, Pioneer, Sony, and Philips involved is a pretty strong representation of core technologies for optical disc. The key issue is to make sure that we could maximize the capacity on the disc. In order to do that, we have to move to a 1.1mm substrate with a .1mm cover layer. That translates theoretically to the highest capacity on packaged media using visible light." Blu-ray disc (BD) is either 25GB on a single layer or 50GB on a dual layer disc (the currently shipping Sony drive works with 23GB discs). The single-layer disc is 1.2mm thick. It is still a two-ply disc, but the information layer (called the cover layer) is just .1mm.
While the BD format has not yet been specified (specs are set for release in the first half of this year), Sony has a BD pilot line production in Shizoka, Japan where over a quarter million single-layer discs have been produced. They have reportedly already reached five-second cycle times.
One of the biggest advantages of BD, according to Sony, BD is its robust copy protection. "The physics of information retrieval at Blu-ray densities mandates changes to the disc form factor and to playback hardware architecture," says Mitchell. "These facts create a unique opportunity in that content protection can be based on interactions between three elements: software, hardware, and the physical disc. Clearly, the ‘software only' approaches the industry has come to rely on are deficient when compared to what Blu-ray can afford," Mitchell continues.
What kind of investment will manufacturers need to make to replicate BD? "At the very least, current DVD injection and sputtering equipment can be redeployed, without modification, towards Blu-ray," says Mitchell. "Depending on the replicator's chosen DVD equipment supplier, the re-use of these sub-systems can represent nearly 40% of a given line's investment cost."
Both new formats will require a new mastering process. For Blu-ray, Phase Transition Mastering or PTM will be used. "In place of glass," Mitchell explains, "we use silicon wafers, in place of photo-resist--inorganic thermosensitive resist, in place of externally modulated gas lasers--direct modulated solid state lasers." Instead of making metal masters, mothers, and stampers, they will plate the stamper directly from the wafer. These differences reportedly yield significant positives including reduced fixed costs, reduced variable costs and reduced environmental impact.
While Sony is continuing development and expects to have a more economical way of forming the .1mm cover layer on the disc within a year, were they to launch the format today, a film cover layer would be applied with a UV-cured resin as the binding agent. "A key advantage of the Blu-ray form factor as it relates to the cover layer and substrate relationship is the fact that the playback laser path no longer passes through the polycarbonate substrate," Mitchell says. "Because of this, the replicator can expect higher yields when forming the substrate which will of course serve to offset cover layer formation costs."
On the other side of the coin, the HD-DVD camp, though not so forthcoming with manufacturing and technical details, is actually farther along in the spec-setting process. Specifications for HD-DVD Read-Only Disc Version 0.9 were approved by the DVD Forum Steering Committee on November 18, 2003. As the spec name suggests, the approval covers only the "read-only" DVD disc; the "rewritable" DVD disc spec remains at large. The approved read-only disc is backwards-compatible and plays on HD and DVD players, according to the DVD Forum.
At the IRMA Summit, Dalla Verde discussed the two formats in limited detail. Here is what we know about HD DVD: It can be single or dual-layer. Each .6mm layer has a 15GB capacity. So far, seven-second cycle times have been achieved; these will improve, Verde said. To master the discs, current mastering and electroforming equipment can be used. Bonding is also the same as it is for DVD. The rewritable version is similar to DVD-RAM—no surprise, considering RAM developers Toshiba and Hitachi (but not Panasonic) are in the HD-DVD camp.
Dalla Verde also said that at Cinram's Olyphant plant, a pilot line has been installed with nearly 300,000 HD-DVD discs already manufactured. Dalla Verde said this pilot line was configured to produce either HD-DVD or BD discs for development purposes, although he admits that the initial BD runs were limited due to the lack of a ROM specification and availability of test stampers.