What is Blu-ray?
These days, many are asking,
what is Blu-ray? It’s one of two high definition video formats (HD DVD is the other) poised to replace
DVDs as the primary media used by consumers for home theater viewing. The format takes its name from the
blue laser that it uses. The Blu-ray Association was founded in 2002 by nine consumer electronics firms,
Matsushita (parent company to Panasonic), Pioneer, Philips, Thomson Consumer Electronics (RCA in North
America), LG Electronics, Hitachi, Sharp, Samsung and Sony. Sony and Phillips are the primary developers
of this format and there is a lengthy list of supporters. The association’s board of directors includes
the 9 founding consumer electronics companies as well as Mitsubishi. Supporting movie studios are
Twentieth Century Fox, Walt Disney and Warner Brothers (who also support HD DVD). Supporting IT companies
are Apple Computer, Dell, Sun Microsystems and HP (who again also support HD DVD).
Blu-ray player pricing begins at $499 M.S.R.P. for a Sony Playstation3 20GB model (if you can find one)
to $1499 for the Pioneer Elite BDP-HD1. Currently Playstation3s are difficult to get, and some retailers
are charging a premium price due to the lack of supply. I have seen prices as high as $899 for the 20GB
Playstation3 from some major internet retailers. The lowest priced standalone players are the Samsung
BD-P1000 at $599 ($469 for a refurbished unit), and the Phillips BDP9000 which also has a street price of
Disc Structure & Data Storage
For the most part, Blu-ray Disc (BD) shares the same disk structure as DVD and HD DVD. The disc
diameter is 12 cm and it is 1.2 mm thick. Where it differs from the other two formats is how close to the
surface of the disc information is stored. For DVD and HD DVD, the information is stored 0.6 mm from the
surface, with Blu-ray it is only 0.1 mm.
One noteworthy characteristic of lasers is that the diameter of the beam spreads out as it moves further
away. With Blu-ray, the laser need only penetrate to 0.1 mm vs. 0.6 for the other mediums. The result is
a 0.85 and 0.65 numerical aperture for Blu-ray and HD DVD respectively. The higher that numerical aperture,
the greater the storage capacity (all other things being equal). Again, Blu-ray achieves higher storage
limits than its HD DVD competitor, because it stores the data closer to the surface of the disc. BD-ROM
media can store up to 23.3 GB and 46.6 GB of information on single and dual layer media respectively. The
blue laser used by the Blu-ray format, has a shorter 405 nanometer wavelength compared to the 650 nanometer
wavelength found in the DVD format. That shorter wavelength allows the laser to achieve greater focus
precision, which also contributes to greater information storage density on BD-ROM media.
Blu-ray Disc media has a special clear polymer costing that provides substantial scratch and contamination
resistance. Backward compatibility with the incumbent DVD standard is not mandatory under the Blu-ray
format; but it is recommended by the association for all players. Currently, all Blu-ray players on the
market are backward compatible. With DVD sales showing no signs of slowing down in the near future, a
player manufacturer would be foolish to market a player that is not backward compatible. Like its rival
HD DVD format, Blu-ray players also have the ability to up-convert regular DVD movies to HDTV quality.
The Blu-ray format can reproduce studio master quality sound, and includes DVD’s mandatory sound
codices (Dolby Digital and MPEG2 audio) as part of its mandatory set. In addition Blu-ray will support
Linear PCM and DTS digital surround as mandatory codices. However, Dolby Digital Plus, Dolby TrueHD and
DTS HD are optional audio streams. So, although big budget Hollywood Blu-ray movies may have Dolby Digital
Plus, Dolby TrueHD or DTS HD encoded as audio tracks, individual Blu-ray players may not be able to support
them. Some of the most expensive first generation Blu-ray players that you would expect to feature the
optional decoders offer only the basic mandatory decoders, an oversight that is puzzling.
Similar to HD DVD, Blu-ray Disc is capable of delivering up to 1080p (1920 x 1080 vertical and horizontal
lines of resolution) to HDTV displays that are capable of accepting and displaying a full high definition
signal. The format calls for the use of MPEG2, MPEG4 or Microsoft’s VC-1 video compression codices when
encoding BD media, and all BD players will be able to decode all three codices. With the use of the
available compression technologies, dual layer Blu-ray Disc media is capable of holding up to 9 hours of
high definition video.
A Java subset called BD-J will be used to provide the interactivity that consumers are demanding. BD-J
is a fully programmable application environment with network connectivity, which will allow content
providers to update complementary content after a disc, has been released. For example, content providers
who release a movie title in one language, can make additional languages (audio or subtitles) available
for download and playback as they become available. So when you view the latest Academy award winning
French film, your player can recognize that your language preference is English, contact the movie studio’s
internet server, and see if an English audio track is now available. The application can also provide the
capability for interactive menus, alternative camera angle picture-in-picture, downloadable movie trailers,
and of course interactive games, (locally stored or downloadable).