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Old 07-22-2007, 08:08 AM   #1  
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Join Date: Jun 2007
Location: Albuquerque, NM
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Default What are all the differences between HD DVD and Blu Ray? Huh?

Hey guys, I'm trying to compile a list of differences between HD DVD and Blu Ray for the forum. And I would like your help in correcting what I have so far. Here it is:


Blu Ray and HD DVD are two formats that are competing to be the next standard High Definition disc [and trying to replace the regular DVD.] They are not compatible with each other, and one disc from one format will not play in the other format's disc player. There are plans for "dual-format players" in the future that will play both discs from both formats. But currently, if you buy a Blu Ray player, you will have to buy Blu Ray discs. Or if you buy an HD DVD player, you will have to buy HD DVD discs.

And although you would think that with both of them being "high definition discs," that they would be very similar, but in fact... they are very different. The differences start in the way they were developed:

First of all, both formats use a blue laser to read the discs, as opposed to the red laser used to read regular DVD's. The blue laser has a shorter wavelength, and thus allows for it to read more data in a short area of space. However, the disc used to store data for each format is difference. The Blu-ray disc has a tighter track pitch (the single thread of data that spirals from the inside of the disc all the way out—think grooves on a 12-inch vinyl), so it can hold more pits (those microscopic 0s and 1s) on the same size disc as HD DVD. And the differing track pitch makes its pickup apperatures different - thus making the two pickups technically incompatible even though they're using similar lasers.

Blu Ray discs also use a different thickness of surface layer compared to the HD DVD (0.6mm on HD DVD's compared to 0.1mm on Blu Rays.) And this thinner surface on Blu Ray discs makes Blu Ray discs more expensive to manufacture. And because of the thinner surface, Blu Ray discs do not share the same thickness of surface layer as the regular DVD's. And machines that make regular DVD's must be specially modified in order to reproduce Blu Ray discs, and this modification is a pricey process. Thus, Blu Ray discs cost more to manufacture, but hold more data than an HD DVD disc. (A single-layer HD DVD disc can hold up to 15 GigaBytes (GB), while a single-layer Blu Ray disc can hold up to 25 GB. And a dual-layed HD DVD disc can hold up to 30 GB, while a dual-layer Blu Ray disc can hold up to 50 GB.)

Another big difference between the two is movie studio support. Blu Ray has more major studio support than HD DVD. The movie studios that are exclusive to Blu Ray are Disney, Columbia (Sony), Twentieth Century Fox, and MGM. The only major movie studio that is exclusive to HD DVD is Universal. And Warner Brothers and Paramount are format neutral. Though, if one format should win, it is expected that all major studios would then support the winner of the format war [whether it be Blu Ray or HD DVD.]

A third big difference between the two formats is price. HD DVD players start at around $250, while the least expensive Blu Ray player is $460 [though the most popular Blu Ray player is the PS3 which is priced around $500 right now.] Though, there are some issues with the current Blu Ray players. For one, Sony has yet to set a standard for Blu Ray compatibility, and many first-generation and second-generation Blu Ray players may not be able to play future Blu Ray titles. This means that a consumer could spend from $500-$1000 on a Blu Ray player that won't work for them in the future. This happened because Sony released Blu Ray before it was a finished product, in order to compete with HD DVD. The makes of HD DVD, however, have set a standard compatibility for their discs and players from day one, and all of their players will work with all current and future HD DVD's.

The good news is that Sony has set a date of 10/31/07 for all new Blu Ray players introduced to be "Profile 1.1" and compatible with all future release. However, this does not necessarily mean if you buy a Blu Ray player after 10/31/07 that you are safe, as the rule only states that Blu Ray Players INTRODUCED after that date need to be Profile 1.1 compatible, and stores may still have only Profile 1.0 players on the shelves after 10/31/07. Thus, it is recommended that if you buy a Blu Ray player, you either wait or make sure that the player is Profile 1.1 so you can be sure your Blu Ray player will continue to work with future releases.

Another difference between the players is ethernet connections. HD DVD requires all of their players to have ethernet connections. This not only allows HD DVD discs to include special extras that include internet interactivity, but also allows HD DVD players to download firmware updates in order to keep the player technically up-to-date. Some blu ray disc players do have ethernet ports, but it is not a requirement of Blu Ray players.

One other difference between the two formats is the compression schemes they use encode movies on disc. Technically, both formats can use the same CODECs [enCOding/DECoding] for playing movies, but the makers of each format recommend different CODECs to their studios to encode movies in. The Blu Ray mainly uses the MPEG-2 CODEC to encode movies, which is the same CODEC used to store movies on regular DVDs. While the HD DVD mainly uses the VC-1 CODEC to encode movies, which is an evolution of the conventional DCT-based video codec design also found in MPEG-2. According to various sources, the VC-1 CODEC is typically judged best in subjective quality testing with other CODECs.

Also, since HD DVD is made by the same people who brought us the standard DVD, the HD DVD people are trying to be user-friendly by making "combo" discs for many HD DVD releases. A combo disc is when an HD DVD release not only includes the high-quality HD DVD version of the movie, but also the standard DVD version of the movie [so you don't have to buy two copies of the movies if you want to play them on non-HDTV sets. ] This may allow an easier transition for consumers from regular DVD to HD DVD. Blu Ray currently does not support combo discs or include standard definition DVDs with any of their releases.


I know there are probably some differences I missed too, anyone know any? I know there's something about audio mandates that I'm missing. And possibly something about HDMI profiles. Any help is appreciated.

Last edited by mswoods1; 07-22-2007 at 08:18 AM..
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