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Saturday, December 06, 2003
 High-Definition TV recorded on BD or AOD?
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Message Text: The CEA (Consumer Electronics Association), a U.S. trade association, estimates that nine million U.S. households are likely to purchase a high-definition TV set sometime between January 1, 2004 and June 30, 2005. Since there are at least five million households that already owned HDTVs at the end of 2003, there will be a rapidly growing need henceforth for home recorders able to record programs' high-definition broadcasts.

Over sixty million U.S. households can already receive HDTV programming from their local cable operator. They may not yet be subscribing to HDTV services, but the infrastructure to supply is already in place. The same is true for several million users of satellite-broadcast programming. A relatively modest number of households are already equipped with a D-VHS recorder, which can record HDTV using special video tape cassettes. These recorders also record to and play back standard VHS and S-VHS cassettes. The picture quality is superb, and Hollywood has made available about 80 movies on D-VHS cassettes. JVC, as one might expect, is championing the D-VHS format, and already has HD camcorders on the market as well as two excellent recorders.

However, many of the industry leaders in Japan and Korea said that they believe the future of high-definition recording belongs to optical disc recorders rather than to those using tape. The big question is not tape vs disc, but rather which optical disc format will become the standard for the HDTV age.

One might think that, this time around, the entire home-video industry would get together and sponsor a single format as the standard for HDTV recorders. Alas, this is not the case; just as there were when DVD-Video was first being readied for market introduction, there are several competing technologies. Moreover, the two most prominent formats being promoted for HDTV are backed by the very same groups that fought over DVD-Video before it was finally standardized. On this side of the fence stand NEC and Toshiba, two giants of the Japanese consumer electronics industry. They are backing their jointly developed "AOD" (Advanced Optical Disc) format for HDTV recording applications. The main argument for AOD is that it is play-compatible with DVD-Video, and is often called "HD-DVD" for that reason. It is in effect an evolutionary higher capacity version of DVD-Video.

Structurally, AOD is identical to DVD-Video, employing two 0.60mm thick discs that are bonded together to form the finished HD disc. AOD recordings can therefore be replicated on the same equipment used to replicate standard DVD-Video recordings. The capacity of a single-sided single-layer AOD disc is 15GB, which its proponents insist is more than adequate for HDTV software applications. The compression algorithms used in AOD are different from those currently in use, and critics complain that their use reduces picture quality to something less than "true" HDTV, whatever that might be..

On the other side stand Sony and Philips, along with Hitachi, Sharp and Samsung. They are promoting the "BD" format, which is better known as the "Blu-Ray Disc". Sony already has Blu-Ray recorders on the Japanese market, and several Japanese companies, including Sony, Hitachi Maxell and TDK, already offer blank Blu-Ray disc media. The recorders and media are expensive, but they are obviously first-generation units whose prices will decline rapidly as market acceptance takes hold.

Unlike the AOD format, Blu-Ray recorders make use of the same MPEG-2 compression techniques used in DVD-Video. MPEG-2 is also the compression algorithm specified in the U.S. HDTV broadcast standard. Blu-Ray media make use of a completely new technology that requires no new advanced compression algorithms, and is totally different from either DVD or HD-DVD (AOD). It will therefore require new facilities for the manufacture of the discs. BD also makes use of a highly specialized high numerical aperture (0.85) lens and what is called near-field recording technology, using a single platter 1.1mm thick, with a special 0.1 focusing overlayer on the active side of the disc. Both AOD and BD use 405nm blue-violet lasers for writing and reading. All DVD-type products require 650nm red lasers and a conventional focusing system, which are both much cheaper than the 405nm lasers and special near-field high numerical aperture lens systems required for a BD recorder or player.

However, we are talking about high-definition television here. Good as DVD is today, it is a far-cry from what is available in HDTV. True HDTV offers picture quality so superior to today’s TV that it would be a shame to choose a recording system that was unable to capture completely and faithfully the incoming signal. AOD requires much higher compression techniques to allow 15GB to be recorded on a single-sided 120mm disc, and 15GB is really insufficient whatever the compression algorithm. BD uses standard MPEG-2 compression on a 120mm disc with a 23.3GB capacity. It stands to reason that there will be discernible differences in the picture quality of these two systems. Readers attending the upcoming CES Show in Las Vegas (early January 2004) will be able to see for themselves, as we understand Sony will be demonstrating BD and AOD capabilities side by side at their booth!

Whatever the differences in quality, or the respective merits of the two systems, there is little question that there is going to be a major fight between the two groups supporting AOD and BD technology. This cannot be avoided, because the financial rewards that will go to the winner will be immense. Unfortunately, the end user as usual will be the immediate loser. This battle between the titans will almost surely delay the introduction of a standard HDTV software format, depriving users of an expanding body of titles and possibly making obsolete after a couple of years the HD recording format they initially chose. It probably will not delay the introduction and sale of rival HDTV recorders, not only in Japan but in the U.S. and the EU as well, because owners of HDTV sets will want some kind of recorder to allow them to time-delay or record for archival purposes certain programs.

Add to this confusion the existence of D-VHS, which is already being used to distribute very high quality HD movies, and the possible introduction in 2005 or 2006 of HDV, a tape-based HD recording format that uses standard DV (digital camcorder) cassettes, and one has the makings of a colossal mess. It will probably take a couple of years to work out of this mess and settle upon a single HD recording format, although it is not impossible that all four systems (BD, AOD, D-VHS, and HDV) will be on the market together, both as recording formats and software distribution vehicles. Add to this the continuing availability of VDRs and other equipment based on DVD technology, and one can only conclude that the immediate future for home video looks like it will be more than a little confused and confusing.
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