[opendtv] Rival display interfaces face off
- From: "Albert Manfredi" <bert22306@xxxxxxxxxxx>
- To: opendtv@xxxxxxxxxxxxx
- Date: Sat, 27 May 2006 15:21:49 -0400
This article demonstrates EXACTLY why analog interfaces for video and audio
will continue to be necessary in the foreseeable future. Talk about
consumers being yanked around by the nose ...
While analog interfaces have stood the test of time, no rational person can
expect that a digital baseband interface will last longer than any other
fad. It's too easy for manufacturers to dream up another variant, since
interoperability among brands is not mandatory or, from a manufacturer's
point of view, even desirable. One wonders why analog interfaces have been
so sensible.
Bert
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Rival display interfaces face off
DisplayPort, UDI duel to deliver digital video
Rick Merritt
(05/22/2006 9:00 AM EDT)
URL: http://www.eetimes.com/showArticle.jhtml?articleID=188100626
San Jose, Calif. -- Video has hit an impasse on the road to the digital
home. This summer, separate groups of engineers will finish work on two
incompatible display interfaces--DisplayPort and the Unified Display
Interface--vying to become the standard for a secure digital link in
consumer systems and computers. The pair will compete against two digital
interfaces already in use--DVI and HDMI.
Thus far, no formal talks are scheduled among advocates of the new
interfaces, and no one knows just how the competition will shake out. The
confusion reflects unresolved conflicts among security, interoperability,
ease of use and low cost at a time when the transition from analog to
digital media is still in its formative stage.
"We've ended up with a nightmare scenario of multiple standards. It's a
frightening mess," said Bob O'Don- nell, vice president of clients and
displays at International Data Corp. (Framingham, Mass.). "The notion of a
converged display interface may just go away."
But "this is a transition period," said Michael Ep- stein, a manager of
technology and standards for Philips Intellectual Property and Standards, so
"everything may not be neat and clean." Epstein is finishing a content
protection approach for DisplayPort that has the latest security features
content owners want, but it will not work with the scheme used in today's
Digital Visual Interface (DVI) and High Definition Multimedia Interface
(HDMI). "It's not clear there's an immediate need for interoperability,"
said Epstein, given that shipments of DVI and HDMI are still relatively low
and the transition to digital still young.
The Unified Display Interface (UDI) uses the same form of content protection
found in DVI and HDMI. But it lacks features, such as longer encryption keys
and proximity restrictions, that content owners want to see in
next-generation systems.
"Everyone would agree having two [new] standards is not desirable. Before
products become integrated [into chip sets in two or three years], we expect
to resolve this--but I don't know how," said Simon Ellis, UDI program
manager at Intel Corp.
All sides agree on the underlying need to shave costs and broaden
interoperability. Thus they want a single, royalty-free technology that
could replace low-voltage differential signaling (LVDS) inside notebooks,
supplant VGA in computers and displays, and link to digital TVs, set-top
boxes and other consumer gear. Content owners fear those older, unsecured
interfaces will put their movies and TV shows at risk of illegal copying, so
digital security to plug this "analog hole" is a key motivation,.
"Analog VGA has been the PC standard for 20 years, but now we are seeing
some pressure for all content to be protected, and we can't do that on an
analog interface," said Bob Myers, who co-chairs the DisplayPort effort and
manages a display technology group at Hewlett-Packard Co. "At some point, we
will have dates by which we need to support copy protection."
According to In-Stat Inc., DVI shipped in more than 60 million systems,
mainly PCs and peripherals, last year, while HDMI went into fewer than 20
million systems, mainly digital TVs and set-top boxes. But the two are
expected to hit parity this year as DVI, which dates back to 1998, peaks and
HDMI--created in 2002--surges.
As early as 2003, a group of PC makers, including Dell and HP, were chafing
at HDMI's technical limits and royalty structure. The charge is roughly 4
cents per system, plus a membership fee that typically runs $15,000 a year.
They developed DisplayPort as a royalty-free option designed to leapfrog
HDMI and DVI on several fronts.
DisplayPort taps the electrical layer of today's 2.5-Gbit/s PCI Express bus
and rides its coattails to bandwidth of up to 10.8 Gbits/s over four
channels. It also delivers a new and improved copy protection scheme.
DisplayPort uses a 128-bit encryption key along with AES, rather than the
40-bit key used in the high-bandwidth digital content protection (HDCP)
spec. It adds support for checking the proximity of the transmitter and
receiver, a new technique to ensure users aren't fooling a system to send
content out to distant, unauthorized users.
The copy protection scheme will not hit a 1.0 draft until later this summer.
Then it must go through approval processes at various content organizations,
such as the Advanced Access Content System, which oversees content
protection for next-generation DVDs.
To sweeten the pot for OEMs, DisplayPort not only aims to replace the aging
VGA, which effectively tops out at today's 1,080-progressive-scan
resolutions. It also wants to replace LVDS, which is being stretched to as
many as 10 pairs of links between a system and display to handle the
bandwidth needs inside today's notebook computers.
Backers including Ana- logix Semiconductor, ATI Technologies, Genesis
Microchip and Nvidia are expected to produce silicon supporting DisplayPort
before the end of the year. Samsung and Philips are also backing the
technology, which was officially approved by the 100-plus-member Video
Electronics Standards Association in a late-April vote.
The rub is DisplayPort's incompatibility with HDCP. "It is not meant to
interoperate, and it doesn't," said Epstein of Philips. "Content providers
want to see security improvements with every generation." OEMs could build
products that support both the new and old copy protection schemes without
much trouble, he added.
Leslie Chard, president of HDMI Licensing LLC, disagreed, citing projections
that by the end of 2006 as many as 300 million systems using HDCP may have
shipped. "How are you going to ask people to use another connector?" Chard
asked. "I have not heard a demand for more protection from the content
owners, nor have I heard a demand for lower royalties from OEMs, and we have
more than 70 HDMI adopters in mainland China."
In addition, although the DisplayPort spec is royalty-free, its contract
stipulates reasonable and nondiscriminatory licensing for any patents that
apply it. "If you are a DisplayPort adopter, you don't know what your rate
will be. Ours is fixed," Chard said, although the HDMI contract does include
adjustments for inflation.
Building on HDMI
For its part, the Unified Display Interface positions itself as a PC version
of HDMI, promoted chiefly by Intel and Silicon Image, a Sunnyvale, Calif.,
chip maker that earlier helped define both the DVI and HDMI specs. UDI seeks
to maintain compatibility with HDCP so that new systems can link to existing
digital TVs and set-top boxes. It is targeted squarely at PCs, leaving its
compatible big brother--HDMI--to own the consumer space.
One thing that's unclear is the road map for HDCP. The technology is owned
and licensed by Intel, but the semiconductor giant's HDCP representative was
not available for comment at press time.
Like DisplayPort, UDI is positioned as both an external replacement for VGA
and an internal replacement for LVDS. It too uses PCI Express and is
available royalty-free. UDI is in 0.8-version draft today. It plans to
follow HDMI's example of using three data channels and one clock channel.
Data rates have not yet been set but are currently estimated to range from
symbol rates of about 5 bits/s at the low end to more than 8 Gbits/s at the
high end.
Systems may need an adapter or a UDI-to-HDMI cable to make a physical link.
Besides Intel and Silicon Image, UDI backers include Apple, LG Electronics,
National Semiconductor, Nvidia and Samsung.
UDI has slightly more bandwidth than HDMI, but it does not support a few of
that spec's more consumer-oriented features, including audio and component
video. That could save PC makers a few cents.
All material on this site Copyright 2006 CMP Media LLC. All rights reserved.
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