So you can both read and write both HD DVDs and normal DVDs, with the same drive. I guess HD DVDs will be popular in the next few years. As far as I can tell, it's o­ne of the few technologies that offers some competition to Blu-Ray discs.

NEC presented o­n the 18th that they have developed interchangeable technology, allowing for the recording and playback of HD DVDs and standard DVDs using the same laser head.

HD DVD is from Toshiba and NEC, who are proposing it to the DVD Forum as the next generation optical disc standard. Until now, it has been known as "AOD." Currently, the HD DVD-ROM Ver.0.9 is approved by the forum for playback. The ROM's capacity is 15GB single layer, and 30GB dual layer.

HD DVD varies from current DVDs in that it uses a blue laser diode (LD) as opposed to a red o­ne. NEC has developed a laser head that can hold both blue and red laser diodes, meaning that both DVD and HD DVDs can be read with the same lens.

Although both red and blue LDs are required, they can be mounted o­n the same head - this (theoretically) means that a drastic reduction in both cost of production financially and physically will be possible.

Also, though there is a vast difference in the physical formats of DVD and HD DVD, the equipment can handle both. HD DVD was created with the intention of being a high density/high volume medium; it uses the PRML (Partial Response Maximum Likelihood) system for playback signal processing. However, the ETM (Eight to Twelve Modulation) demodulation system has been developed for recording  compatibility.

At the meeting, NEC's Performance Official, Hisatsune Watanabe said, "This complements how movie contents are turning digital, as are BS Digital/Terrestrial Digital Broadcasts; it is also a visit to the High Definition era. As is appropriate for the HD era, high-volume, easy to use playback and recording equipment is sought," as he stressed that HD DVDs will be demanded by the market.

Also, he mentioned that HD DVDs are appealing because they are more or less continuing in the path laid by DVD: "...a seamless advance from DVD is being sought after." HD DVDs also inherit a lot of the technical aspects of DVD, the same manufacturing processes, and share high affinity with current DVDs.

Next, the company's research department head, Hiroshi Ineda explained the development points.

 The newly developed interchangeable head consists of a non-spherical lens with diffraction grating and a wavelength choosing orifice. The interchangeable head was accomplished by having the diffraction grating discern the difference in wavelength, which then chooses the correct orifice count suitable for the wavelength.

He also explained other newly developed technologies, from the PRML adaption model to high density volume discs and playback achieved by use of the ETM type technologies.

In regards to the practical applications of HD DVD, he began by saying "While looking at the situation of standardization..." and continued with "The killer app/contents of movies and PCs will be essential, but that is not until 2005. The image of the plan is not the sudden replacement of DVD, but the gradual replacement."

At the meeting venue, a playback demonstration using a HD DVD drive was o­n display. A 19Mbps MPEG-2 movie was played o­n a 30 inch display, where NEC prepared the contents and Memorytech made the HD DVD-ROM.

Though this time around was o­nly playback, the demonstration unit "also has recording functions." But, since the application standards have not been finalized, it cannot record images. Also, though playback of current DVDs is possible, in regards to writeable DVDs, they more or less ran away by saying "we are looking into it."



Original Article:
http://www.watch.impress.co.jp/av/docs/20031218/nec.htm

News Release:
http://www.nec.co.jp/press/ja/0312/1801.html