VMD the red laser HD way

In March, NME demonstrated its Versatile Multilayer Disc format at CeBIT. Inserted in a player that looked like a usual DVD player, the 20GB and 40GB VMD discs played back 3-hour movies in the High Definition format of 1920/1080, 60i. The company’s CTO, Dr EUGENE LEVICH unveils the technology behind it.

An immediate result of this first public demonstration was the realisation that VMD technology is available now to all manufacturers of DVD players who have been awaiting the arrival of players with a blue laser readout and a promised capacity of 30 GB. Interest was further heightened by the fact that the VMD technology uses the long-established red laser for readout in the player, and a consumer selling price of VMD products is in the same range as current DVD players.

Marketing negotiations are now in progress with content providers, distributors and DVD manufacturers in the USA, India, China and Western Europe, based on deliveries of VMD players to commence in the third and fourth quarters of 2006.

NME may be small and not well known so far. But it has nothing to be ashamed of in terms of its broad international scientific and engineering staff and management, American, English, Indian, Russian, and Chinese sprinkled with some Israelis.

The quest for greater capacity via multi layers

The need for more optical storage than is allowed by the present day DVD is well understood and not disputed. Invasion of HDTV into our homes, advent of Digital Cinema and storage hungry 3-D computer games are sufficient reasons for investing big effort and resources towards the development of post-DVD products.

Technologically, DVD was an incredible step over CD – nearly a 10-time increase in storage capacity, 4.7 GB for one layer (DVD-5) and about 7.8 GB for a two-layer disc. The next revolution in optical storage should be a similar technological leap with 50-100GB discs. Anything less than such a storage capacity increase is not a revolution.

The currently proposed technologies based on blue lasers seem so far to fall short of a revolution. HD DVD offers 15 GB for one information layer of playback disc and Blu-ray 22-25 GB. For both technologies, the ability to go multilayer – over two layers – has not been demonstrated so far.

Furthermore, gigantic efforts will have to be invested in rebuilding the existing DVD industrial infrastructure to be able to mass produce the new-generation blue laser-based discs and drives.

After exhaustive and, at times, painful R&D investigations, NME scientists designed methods of manufacturing multilayer discs without substantial changes in the existing DVD industrial base. On the hardware side, we invented a sophisticated technology for reading multilayer discs using practically entirely the DVD optoelectronics.

In other words, it is economically feasible to manufacture high capacity discs and players/recorders using the existing DVD industrial infrastructure. For consumers it means that the price of such discs will not be substantially higher than that of a standard DVD.

The strength of the VMD technology is that the principles for manufacturing discs and playback/recording equipment remain the same for any reading laser wavelength. As soon as the technology of blue lasers and associated industrial infrastructure mature and become commercially affordable we will build blue laser VMD with truly large capacities of 50-100GB. Although theoretically it is possible to build even 100 GB with upgraded DVD technology, I personally believe that the limit of red laser technology is at about 40 GB. After that starts the domain of blue lasers.

An important feature of VMD is that it is an open technology and is not slaved to any format. It can be applied and used with various formats. In particular, it can be fruitfully married with the EVD format developed and marketed by Beijing E-World Technology, now our partner. EVD is a true High Definition system on red laser. The telecine, editing, encoding/decoding tools and finally the video output are entirely HD 1080i or 720p formats. Besides, the EVD system is endowed with very advanced tools for protecting content against piracy, and has probably the best audio capabilities around.

The VMD disc

The VMD disc has the same size and thickness as a DVD. The disc consists of a number of information layers on which video data is imprinted by stampers. Intermediate layers separate the information layers, and all are bonded together to form a single optical disc – the Versatile Multilayer Disc or VMD.

The key word is ‘Multilayer’. Here lies the basic difference with DVD. The DVD comes as a single layer containing 4.7GB storage capacity (DVD-5) or two-layer one-sided DVD-9 containing about 7.6 5GB.

VMD has at least four information layers on one side of the disc. The four-layer VMD-20 contains 20GB storage capacity. The eight-layer VMD-40 version contains 40GB storage capacity. The numbers are approximate, as VMD-20 can have up to 24 GB, for instance. It is possible without pain to increase the capacity to 6 GB per layer. There is no loss of capacity from one layer to another, as it happens in DVD-9.

There were two basic reasons why multilayer discs were abandoned by big companies. The first one is technological. In order to make more than two layers it is necessary to use what Philips called 2p technology – almost everything associated with application of photopolymers for the creation of information layer with subsequent UV (ultraviolet curing).

The 2p technologies are difficult in mass production and engineers are almost universally suspicious of them. In contrast, DVD-9 is made by bonding machines, still using photopolymers, but only for the purposes of gluing, by UV curing, back to back of the two halves of the DVD-9 disc.

The 2p approach is used for all recordable blue laser discs having more than one layer. It is unavoidable for manufacturing Blu-ray discs and over two-layer HD DVD discs. The problem of 2p technology with blue laser technologies will likely surface when discs will hit the market.

Here, NME made a breakthrough. We created an error-free approach analogous to 2p technology. Now tested in DVD industrial environment, the VMD 2p technology seems to work perfectly well, equally for red, blue or any other color laser. Now patented, the technology applies as well to DVD-R double-layer and multilayer recordable discs of the future.

Another reason why multilayer discs were not seriously considered before is the problem of cross talk between the layers. When a laser beam focuses on a particular layer, light also hit other layers though unfocused. Therefore, the useful signal reflected from the targeted information layer is contaminated by interference from adjacent layers, thus it cannot be read reliably. This is briefly and crudely the main source of interlayer cross talk.

Again, NME has solved this problem with a patented technology that does not require hardware modification in the existing DVD players. We can place information layers as close as 15 microns between each other and there is no cross talk. Paradoxically, the more information layers there are, the less the cross talk. For the blue lasers the parameters are somewhat different, but as good.

As far as VMD players and drives are concerned, the mechanical system varies considerably among different manufacturers. The VMD player can be assembled with components of recent versions of DVD players with minor technical enhancements.

The main difference and advantage of VMD player over a DVD unit is that it is fitted with an HD decoder. Every DVD player contains a standard DVD decoder. But the HD decoder processes at least five times greater video data flow with four times the speed of the usual DVD decoder.

The VMD-EVD player developed and commercialised by NME partner Beijing E-World is using an HD decoder build on a LSI Logic chip. More sophisticated chips will be commercially available for NME in the next several months.

Applications

The fact that VMD has so much more physical storage capacity than DVD makes it the ideal choice for a whole array of applications.

The simplest niche application for VMD is recording of several feature films on a single disc or in other words – several DVDs could be copied on to a VMD.

VMD enables mobile storage of large software applications and data bases for industry, construction, design, etc. Such software would sometimes need to be transported on hard discs or several DVDs. (Suitable for all pre-recorded data storage four or eight times larger than DVD).

HDTV and Digital Cinema. The quality of a video is primarily determined by the number of pixels for digital video (or lines for an analogue video) that our eye sees on a screen. If the screen is genuinely high definition it means that it has at least 1080 horizontal lines with 1920 pixels in each line. Video data which is viewed on a screen with such resolution is called HD 1080 video format.

Another important area is sophisticated computer games with high resolution 3D graphics. Imagine a new computer game such as Star Wars that requires more than two DVD discs and subsequent necessity to substitute them during the game in a computer slot. With VMD technology the same game or even two such games will be on one single side disc with the same retail price. Furthermore, VMD’s huge storage allows creating a new generation of computer games with ultimate, truly life like 3D graphics.

Content Protection

VMD discs are endowed with a complex series of multi-level software and hardware data protection features.

VMD Content Protection System (WCPS). This algorithm is a data encryption and authentication scheme intended to prevent copying video files directly from VMD-Video discs.

Serial Copy Generation Management System (CGMS). This system prevents initial copies being copied (copies of copies).

High-Bandwidth Digital Content Protection (HDCP, DVI, and HDMI). HDCP was designed for digital video monitor interfaces.

The protection system does not allow copying data from the disc to computer or any other type of data storage.

VMD uses proprietary encryption algorithms based on most advanced methods of data protection much more powerful than the broken DVD (video) CSS protection. Importantly, the protection system is vastly helped by the multilayer VMD structure and is intended to solve the analogous protection problems as does CSS, but with much higher reliability. The VMD Content Protection System Encryption Algorithms is based on the same algorithms used in HD-DVD and Blu-ray Protection System.

The manufacturing of VMD will be started on modified DVD industrial lines. The first such lines will be manufactured for us by VDL-ODMS (Eindhoven, The Netherlands) where our technologies, in particular 2p, were extensively tested. Many of the established DVD replicators will be able to make VMD without costly investment or complicated restructuring of industrial cycle. Thus, the cost of producing VMD discs will be roughly the same as DVDs.
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