Description
This article is from the DVD Formats
FAQ, by jtfrog@usa.net (Jim Taylor) with numerous
contributions by others.
2.12 Will high-definition DVD or 720p DVD make current players and discsobsolete?
Not for a long time. HD-DVD "technology demonstrations" being made by
various companies do not mean that HD-DVD is around the corner (the
demonstrations mean only that companies are busy jockeying for technology
and patent positions in developing the future DVD format). Consider that
U.S. HDTV was widely anticipated to be available in 1989, yet was not
finalized until 1996, and did not appear until 1998. And has it made your
current TV obsolete yet?
HD-DVD (HD stands for both high-density and high-definition) may be
available in 2003 at the very earliest, though 2006 is more likely. It will
use blue or violet lasers to read smaller pits, increasing data capacity to
around 20 GB per layer. MPEG-2 Progressive Profile--or perhaps another
format such as H.263--will be used to encode the video. All ATSC and DVB
formats will be supported, possibly with the addition of 1080p24. HD-DVD
players will play current DVD discs and will make them look even better
(with progressive-scan video and picture processing), but new HD-DVD discs
won't be playable in older DVD players (unless one side is HD and the other
standard DVD).
Ironically, computers will support HDTV before settop players do, since 2x
DVD-ROM drives coupled with appropriate playback and display hardware meet
the 19 Mbps data rate needed for HDTV. This has led to various "720p DVD"
projects, which use the existing DVD format to store video in 1280x720
resolution at 24 progressive frames per second. It's possible that 720p
DVDs can be made compatible with existing players (which would only play
the 480-line line data).
Note: The term HDVD has already been taken for "high-density volumetric
display."
Some have speculated that a "double-headed" player reading both sides of
the disc at the same time could double the data rate or provide an
enhancement stream for applications such as HDTV. This is currently
impossible since the track spirals go in opposite directions (unless all
four layers are used). The DVD spec would have to be changed to allow
reverse spirals on layer 0. Even then, keeping both sides in sync,
especially with MPEG-2's variable bit rate, would require independently
tracking heads, precise track and pit spacing, and a larger, more
sophisticated track buffer.
See 2.9 for more information about HDTV and DVD.
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pc, dvd, dvd-rom, dvd-video, DVD-R, DVD-RAM, DVD-RW, DVD+RW, recording, playing
