by
George Graves
September 10, 2006

This, at last, is the year of the high-definition DVD. After several years of false starts and pushed-back release dates, the industry has finally deemed the time right to introduce the new format. Did I say format? I should have said formats. There are two competing formats for DVD-based high-definition program delivery and both are the brain-children of the large Japanese and Korean consumer electronics conglomerates. And they are incompatible with one another.

Since the Christmas buying season is almost upon us, we thought this would be an opportune time to contrast the two systems in terms of cost, features, program availability and performance.

High-Definition DVD - The Need for Higher Density Storage

The entire problem with getting high-definition DVDs to market has been one of data density. A 1080i program requires four times the storage capacity of the same program at standard resolution. For example a normal, single-layer DVD, with its 4.7 Gigabyte capacity, is capable of holding about two-hours of SD program content at 3-10 Mbits/second using MPEG2 compression (the rate depends, of course, on the compression level used by the disc maker). At high-definition densities and at bit-rates of 12-39 Mbits/second, that single-layer DVD will only be able to hold one-half hour of a 1080i program.

A dual-layer DVD can contain up to nearly four hours of standard resolution video on its roughly 8.5 Gigabytes, and by using dual-sided discs almost eight hours. But most DVD players require that dual-sided discs be flipped over because the player lacks two-sided playback. Therefore, dual-sided DVDs are fairly rare and most content providers would rather include a second disc in the package.

To hold an HD movie on a standard DVD would require multiple discs with only an hour of programming on each, which is an awkward method. The challenge, then, is to increase the density of the little 12cm disc to the point where it can easily supplant the standard DVD as far as both playing time and convenience are concerned.

HD-DVD

In 2003 a consortium of consumer electronics companies spearheaded by Toshiba came up with a format using a 405nm blue-violet laser to create a dual-layer DVD with a capacity of 30 Gigabytes, over six times more than a standard dual-layer DVD. (Toshiba has recently demonstrated a three-layer disc that will give a capacity of 45 Gigabytes which the current generation of players will play, but it's up to the content providers to decide when and where to employ that much storage.)

This 30 Gig capacity of a two-layer disc is sufficient to hold most feature films in not only high-definition 1080p versions but in a standard definition version as well. This makes the HD-DVD universally compatible. Movie companies can sell one version of a given title and it will play on regular DVD players and on HD-DVD players as well.

The video CODECs (enCOder/DECoder) supported by HD-DVD are the standard MPEG-2, as well as several new compression schemes, Video Codec 1 (VC1), and H.264/MPEG-4. According to Toshiba, a single layer (15 Gigabyte) HD-DVD can hold up to four hours of HD content using VC1 or H.264/MPEG-4 and a dual-layer can hold almost eight hours! That's four two-hour feature films. All program material released to date on HD-DVD has been 1080p but the format can support a wide range of resolutions including 480p, 720p and 1080i. So far, the HD-DVD players on the market lack 1080p outputs, but this is obviously planned for the future as more 1080p capable monitors become available.

Sound-wise, HD-DVD supports up to 7.1 channels of uncompressed PCM audio as well as the usual compressed formats of Dolby 5.1 digital and DTS. In addition, several new formats are also supported. These include Dolby Digital Plus and the lossless compression formats Dolby TrueHD and DTS HD.

Blu-ray

Blu-ray was developed by a consortium consisting of Sony, Philips, and Samsung with support from Pioneer, Panasonic, LG, JVC and Sharp among others. Blu-ray, like its competitor HD-DVD uses a 405nm blue-violet laser diode. Where it differs from HD-DVD is that it uses a more finely focused optical system to elicit a greater capacity from the 12cm disc format. While the HD-DVD is limited to about 30 Gigabytes dual-layer, the Blu-ray format can hold up to 50 Gigabytes dual-layer.

Currently, the industry has decided to encode Blu-ray DVDs using MPEG-2 instead of the newer H.264/MPEG-4 or VC1 CODECs (even though the players will support the newer CODECs). MPEG-2 is not as dense a compression method as are the newer CODECs, which means that Blu-ray needs more disc space than HD-DVD for the same program. Like HD-DVD, Blu-ray players can playback standard video DVDs.

In the audio department the Blu-ray specs support 7.1 linear PCM as well as the lossless Dolby TrueHD and the DTS-HD formats. In addition, Blu-ray also supports Dolby Digital Plus. Mandatory in every disc released are Dolby Linear 5.1, Dolby 5.1 Digital, and DTS 5.1 because every player will be able to decode any one of these formats due to built-in circuitry. Blu-ray discs will also be able to support encoding in up to 24-bit/192 kHz for up to six channels, or up to eight channels of 24-bit/96 kHz encoding. Curiously, for a Sony developed product, Blu-ray does not support the SACD format.

The Image Constraint Token

One very controversial feature of both HD-DVD and Blu-ray formats is the inclusion in the basic specifications for conforming to the AACS LA (Advanced Access Content System License Authority), which calls for the disc maker to set a flag in the program called the ICT or Image Constraint Token. ICT restricts analog output of HD material to 960 by 540, which thwarts making HD copies through unsecured analog outputs. HDMI connections are already copy protected by High-Bandwidth Digital Content Protection (HDCP).

In theory, if the ICT was flagged on a DVD, and you owned an older HDTV monitor that lacked the current HDCP (High-definition Copy Protection) HDMI digital video interface, you would be unable to display the HD-DVD movies in high-definition resolution.

Paramount is a strong supporter of ICT and it seems that Universal and Warner Home Video will likewise use this protection. Part of the AACS agreement makes it mandatory for titles incorporating this protection to state so boldly on the disc's packaging. While Blu-ray also conforms to the AACS LA Image Constraint Token (ICT) standard, most of the major studio signatories to this format have announced that they will not be implementing the ICT on their disc releases. These include Sony/Columbia, MGM, Disney and Fox. Warner Home Video and Universal, who plan to support both HD-DVD and Blu-ray, say that they may or may not set the ICT in Blu-ray releases, but Paramount, the major AACS LA proponent, will definitely be setting the ICT flag in its Blu-ray releases.

Lately, there have been rumors that Hollywood and the equipment manufacturers have signed a secret agreement not to implement ICT until 2010 or 2012, giving people time to naturally replace their aging, non-AACS compliant HD monitors with new ones. This rumor is unsubstantiated at the present time, but as a side note, the HD-DVD discs that I have seen in the video store don't have the ICT label on them, and they are supposed to do so if the disc has implemented the token.

If such an agreement has been reached, then this whole HDMI / non HDMI issue is moot. Still, if your HD monitor is more than a year or so old, you might want to check your owner's manual to see if your monitor complies with the HDCP digital interface standard. If not, you might want to wait until it is known for sure whether or not ICT will be implemented immediately before you contemplate the purchase a high-definition player.

What's Available

Right now, HD-DVD is outselling Blu-ray by about a third, likely due to the cost differential in the players. A Blu-ray player is currently listing at between $1000 and $1500 while HD-DVD players are selling from roughly $460. The cost difference should be minimized as Blu-ray second generation players are due before Christmas 2006 at more competitive prices.

On the actual title front, HD-DVD is, again, ahead of Blu-ray. By the time you are looking for stocking stuffers, the HD-DVD backers hope to have about 200 titles available. Blu-ray shouldn't be that far behind. Of course, these projections may be optimistic. By the first of September, about 90 HD-DVD titles have been released as opposed to 70 for Blu-Ray. To see lists of current and planned releases, check the official websites, www.thelookandsoundofperfect.com (for HD-DVD) and www.blu-raydisc.com (for Blu-ray). We find that Paramount and Warner seem to be supporting both formats:

Conclusion: Which One Is For Me

If a high-definition DVD player is on your Santa's list this year, welcome to the world of early adopters. As one, please realize that you are stepping into new territory with shifting sands. For example, several sources have reported that HD-DVD has a superior picture to Blu-ray.

According to Nathan Plain, a video engineer at Oppo Digital in Mountain View, CA, the reason for this has to do with teething problems on the Blu-ray disc manufacturing side. The Blu-ray consortium is having trouble manufacturing the two-layer discs so all current Blu-ray discs are single-layer.

To fit a standard movie onto the disc, the film producers are forced to use about half the bit-rate that the system is supposed to employ. Therefore the movies are transferred at only 18 MB/s instead of the 36 MB/s that the Blu-ray spec calls for. MPEG-2 is more lossy than VC1 anyway, and exhibits more unwanted video artifacts. This problem is exacerbated by the extremely low bit-rate at which the data is being streamed. I suspect when the Blu-ray group gets their mastering/manufacturing problems solved, this perceived difference in quality between the two formats will disappear.

If you were to choose a format right now, the smart money is probably on HD-DVD. The players are cheaper, more titles are available and these units are the current sales leaders. On the other hand, prices for Blu-ray players are set to fall quickly and reach parity with the HD-DVD players, probably before Christmas, so HD-DVD's market advantage may disappear fairly quickly.

Keep in mind that neither format is supported by all film companies, that's the price we, as consumers, pay for being, once again, the pawns in a format war. The consumer electronics giants have millions invested in their respective formats, and neither is likely to give in without a fight. Even so, there has to eventually be some kind of resolution to this conflict of technologies and one of several scenarios will likely play itself out. Either each will co-exist with the other, and the consumer will be able to buy a single player that will support both (as in the SACD/DVD-A wars), or one or the other will capitulate (as in DIVEX vs. DVD). It's also possible that neither will catch on with consumers and the whole idea of high-definition programming on DVD will just fade away.