2008年10月12日星期日

Blu-ray, HD DVD, and DVD formats compared

Blu-ray and HD DVD are rival incompatible formats, a situation that recalls the Beta versus VHS battle that stifled the early growth of the VCR and home-video market in the late 1970s and early 1980s. Despite an attempt to unify the two standards in 2005, the corporate godfathers of the two formats--Sony for Blu-ray and Toshiba for HD DVD--failed to come to an agreement.

What that means to you is that no standard Blu-ray player will be able to play HD DVD discs, and no standard HD DVD player can play Blu-ray discs (pricey combo players are the exception), but DVD Ripper software can rip HD DVD and protected DVD. If a movie comes out in one format, there's no guarantee that it will be available in the other. Certain studios could release movies in both formats, but you'll still have to be careful not to buy the wrong version of the movie. Adding to the frustration is the fact that the capabilities and features of the two formats are far more similar than they are different--as shown by the chart below.

Feature
DVD
HD DVD
Blu-ray
Maximum native resolutions supported via HDMI
EDTV (480p)
HDTV (720p, 1080i, 1080p)
HDTV (720p, 1080i, 1080p)
Maximum image-constrained native resolutions supported via component video1
EDTV (480p)
EDTV+ (960x540)
EDTV+ (960x540)
Disc capacity
4.7GB (single layer)8.5GB (dual layer)
15GB (single layer)30GB (dual layer)51GB (prototype triple layer)
25GB (single layer)50GB (dual layer)100GB (prototype quad layer)
Video capacity (per dual-layer disc)2
SD: approximately 3 hoursHD: n/a
SD: approximately 13 hoursHD: 5.1 or 3.3 hours, depending on encoding method
SD: approximately 23 hoursHD: 8.5 or 5.6 hours, depending on encoding method
Audio soundtracks3
Dolby Digital EX, DTS-ES
Uncompressed linear PCM, Dolby TrueHD, DTS-HD Master Audio, Dolby Digital Plus, DTS-HD High Resolution, Dolby Digital, DTS
Uncompressed linear PCM, Dolby TrueHD, DTS-HD Master Audio, Dolby Digital Plus, DTS-HD High Resolution, Dolby Digital, DTS
Manufacturer support (home theater)4
All
Toshiba, LG, Thomson/RCA, Onkyo, Samsung
Hitachi, Mitsubishi, LG, Sharp, Sony, Panasonic, Samsung, Philips, Thomson/RCA
Manufacturer support (PC storage)4
All
Microsoft, Intel, HP, NEC, Toshiba
Apple, Dell, BenQ, HP, LG, Panasonic, Philips, Pioneer, Samsung, Sony, TDK
Studio support4
All
Paramount, Studio Canal, Universal, Warner (until end of May 2008), the Weinstein Company, DreamWorks Animation
Sony Pictures (including MGM/Columbia TriStar), Disney (including Touchstone, Miramax), Fox, Warner, Lions Gate
Compatible video game consoles
PlayStation 2, PlayStation 3, Xbox, Xbox 360
Xbox 360 (via external HD DVD accessory, sold separately)
PlayStation 3
Player prices
$99 and less
$130 (Xbox 360 accessory); $150 and more (stand-alone players); $999 for combo player
$399 (PlayStation 3); $499 and more (stand-alone players); $999 for combo player
Movie prices
$6 and more (retail)
$20 to $28 (retail)
$20 to $28 (retail)
Number of titles available at the end of 2007
50,000-plus
about 330
about 360
Players are backward compatible with existing DVD videos
Yes
Yes
Yes
Set-top recorders available now
Yes
No
No
"Managed copy" option5
No
Yes
Yes
Copy protection/digital rights management6
Macrovision, CSS
AACS, ICT
AACS, ICT, BD+, BD-ROM Mark
Region-coded discs and players7
Yes
No (currently; could change in future)
YesSources include: thedigitalbits.com, dvdfile.com, blu-ray.com, Toshiba HD DVD, Blu-ray Disc Association, CNET News.com, Business Week, EngadgetHD, About.com, and WikipediaNotes

Each movie studio may choose to implement the image-constraint token (ICT) on a disc-by-disc basis, which constrains or downconverts the movie's resolution to 960x540 via the component outputs (HDMI output remains at full resolution). However, most major studios--Sony (Columbia/Tri-Star/MGM), Fox, Disney, Paramount, and Universal--have publicly stated that they will not make use of ICT, at least initially. There are even rumors of a backroom deal among studios to withhold use of ICT on HD disc releases through 2010. If true, movies from those studios will display at full resolution via the component outputs.

Video capacity will vary depending upon the type of encoding used. Discs encoded with MPEG-4 or VC-1 offer more compression and, therefore, more video per gigabyte (standard-definition or high-definition) than those encoded with the older, less efficient MPEG-2 codec.

Nearly all HD DVD and Blu-ray discs offer one or more of the new, higher-resolution audio soundtracks, but the ability of players to deliver them varies widely. All current standalone HD DVD players can decode Dolby TrueHD and deliver it via HDMI as uncompressed PCM that most HDMI-equipped AV receivers can handle; or via multichannel analog outputs. Some Blu-ray players can do the same, but some cannot as it is not required by the Blu-ray specification. If the player cannot pass the full resolution of the soundtrack, it will pass a lower-resolution "core" surround soundtrack that's equal to or slightly better than standard Dolby Digital or DTS. There are currently players available in both formats capable of passing DTS-HD Master Audio and Dolby True HD in bitstream format, but not all players can do this.

Manufacturer and studio support is subject to change. With the exception of Sony's devotion to Blu-ray and Toshiba's to HD DVD, other manufacturers and studios can (and already have) switch sides, or they can support both formats. Also, the depth of support for companies aside from Sony and Toshiba has yet to be determined; for many of them, "supporting" one or both of the formats has been limited to issuing press releases or scheduling future product and/or movie releases that remain theoretical until they are available for purchase by the public. Meanwhile, Microsoft's support for HD DVD does not preclude Blu-ray compatibility for Windows; Blu-ray discs will be usable with Windows XP and Windows Vista PCs through the use of third-party software and hardware.

Managed copy refers to the ability to make an HD DVD or Blu-ray movie viewable via a home network or a portable video device. The details haven't been worked out yet, leaving managed copy as more of a theoretical option than a usable feature for the foreseeable future.

It is likely that HD DVD and Blu-ray will feature additional copy-protection methods (including Macrovision or other protections for analog outputs) than the ones listed here.

As of spring 2006, HD DVD discs and players are not region-coded, but that could be changed at any point in the future--for example, the appearance of region-coded discs and a firmware upgrade for the hardware needed in order to play them. Blu-ray discs are coded to three regions (roughly, the Americas and Japan; Europe and Africa; and China, Russia, and everywhere else not included in the previous two regions) that are far more streamlined than the nine-region DVD system. That said, HD DVD and Blu-ray players should honor the nine-region system when playing standard DVDs--so don't expect to play out-of-region discs.

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