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UDI demise sparks HDMI-DisplayPort battle

Posted: 01 Mar 2007 ?? ?Print Version ?Bookmark and Share

Keywords:Unified Display Interface? HDMI? DisplayPort? interface? high-definition multimedia interface?

The Unified Display Interface (UDI) has been effectively killed, the victim of Intel Corp.'s exercising its prerogativewith a little prodding from key customersto change its mind. With UDI's demise, a new battle to crown a convergence digital display interconnect will play out over the next few years.

On one side is DisplayPort 1.1, with deep mind share in the PC world but no silicon ready for production until about June. On the other is the high-definition multimedia interface (HDMI), which shipped in an estimated 60 million HDTV sets and other consumer systems in 2006a figure that could double this year.

There's no disputing the appeal of having a single interconnect suitable for sending high-definition (HD), copy-protected content to displays from both media-rich consumer PCs and consumer video systems. But for now, the PC camp is going for DisplayPort and the consumer crowd for HDMI.

UDI was supposed to unite the two sides. Launched in 2005, the interface used HDMI's underlying technology but tweaked it to respond to the concerns of the PC world. It even had strong backing from Intel.

Penny pinchers
But penny-pinching PC makers could not reconcile themselves to UDI's $10,000 annual fees and 4 cent/portal royalties (most of it going to chipmaker Silicon Image Inc., holder of much of the intellectual property behind HDMI). What's more, PC makers had their own ideas for an interconnect that could not only handle digital copy-protected HD video to a display, but also replace the LVDS interconnects that are running out of gas in notebooks and monitors.

Thus, DisplayPort emerged, hatched by a handful of companies that took it to the Video Electronics Standards Association in 2005 to formalize it as a standard.

Dell, Hewlett-Packard and Lenovo were among DisplayPort's early backers. Intel faced what was in effect a mutiny by some of its top customers, and in January, it publicly reversed course. Both Intel and Samsung formally threw their weight behind the VESA DisplayPort 1.1 specification, sounding the death knell for UDI.

DisplayPort backers tout their interconnect as the digital successor to analog VGA, DVI used on TVs and PCs, and the LVDS links used inside notebooks and monitors.

HDMI backers, for their part, had insisted that some OEMs remained interested in UDI. But that may no longer be the case.

"Samsung has been the only panel maker involved continuously in both efforts," said Brian Berkeley, VP for advanced technology at Samsung Electronics' LCD unit, and "at this point, we have received many inquiries about DisplayPort support from major computer companies and no inquiries about support for UDI."

Conquered champion
Simon Ellis, an Intel technology manager whose business card still reads "UDI champion," said his company now backs DisplayPort 1.1 as the way forward.

"We realized two PC technologies could not be successful," Ellis said. "The connector is the stickiest component in the PC. There is huge resistance to any new connectors because once you put them in and have third-party products linking to them, it is very hard to take them away."

PC camp is going for DisplayPort and consumer crowd for HDMI.

Intel has been quietly working in the background for about a year to port its High-Bandwidth Digital Content Protection (HDCP) software from HDMI to DisplayPort, which uses a very different architecture, said Don Whiteside, director of technology standards and policy at the company. HDCP version 1.3 is now available for both HDMI and DisplayPort.

Three chipmakers are working to integrate HDCP 1.3 into their sampling chipsets: Genesis Microchip, Analogix Semiconductor and Parade Technologies Inc., a startup focused solely on DisplayPort silicon.

Bruce Montag, a technology strategist for Dell, made the case for DisplayPort. Because it can replace VGA and both DVI external and LVDS internal links, it will support large volumes and keep costs low, he noted. DisplayPort has an extensible micropacket-based architecture, unlike the raster scan architecture of HDMI, and thus can support novel features for video and voice calling. And it supports a road map to quad HD displays and beyond.

Road bump
One bump in the road is that PC makers will have to supply dongles to link DisplayPort connections to existing HDMI and DVI peripherals.

Bob Myers, a distinguished technologist in HP's display unit, doesn't have a problem with two coexisting formats. HDMI, he said, is well-suited to HDTV sets, whereas DisplayPort will be used on PCs, PC monitors, projectors and notebooks.

"We don't see competition between HDMI and DisplayPort. They will both be used in different markets," Myers said.

In today's convergence markets, however, companies such as Dell and HP sell big-screen TVs that link to Media Center PCs as well as to STBs. That means the two interconnects will ultimately come into some market conflict, a reality for which HDMI backers are already gearing up.

Les Chard, head of HDMI Licensing LLC, said HDMI has been and will continue to be used in a growing group of PCs and has unique advantages over DisplayPort. "We are every bit as fast as they are, and we are not limited on data rates in the future," said Chard.

As for OEM resistance to the fees and royalties charged for HDMI, Chard noted that while VESA is making DisplayPort available at no cost, the companies behind the spec are permitted to charge "reasonable and nondiscriminatory" royalties, which have yet to be determined.

DisplayPort enables low-cost direct-drive PC monitors.

Royalty structure
Chard recently presented the HDMI royalty structure to members of China's largest manufacturing group, and he claims its members found the terms acceptable. "I expected blowback, but I didn't get any," he said.

HDMI has two features DisplayPort lacks, Chard added. It automatically corrects the A/V sync when latencies in video processing shift the picture out of sync with the audio track. And it has a "consumer electronics control" feature that lets one remote control manage a range of connected devicesa handy feature in the multibox world of home HD theater.

DisplayPort backers counter that their technology's micropacket architecture and auxiliary channel open the door to a host of interactive features they will add over time. Many of those features would be impossible to implement in HDMI's raster scan architecture, they say.

PC makers also aim to build low-cost, entry-level "direct drive" PC monitors that will be controlled by the host computer and thus will dispense with a handful of chips used in today's monitors.

One problem with HDMI is its lack of AC coupling, which prevents the silicon from moving to finer technologies. Chard said AC coupling is "next on our road map."

- Rick Merritt
EE Times

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