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HDMI will boost data rate to 275MHz

Posted: 01 Aug 2006 ?? ?Print Version ?Bookmark and Share

Keywords:Rick Merritt? EE Times? High Definition Multimedia Interface? HDMI? HDMI 1.3?

An upgrade to the High Definition Multimedia Interface (HDMI) opens the door to improved picture and audio quality for high-end users and specifies a smaller connector for OEMs. However, the group backing the ad hoc HDMI standard for transmitting digital media over a copy-protected link has postponed an addition that would support AC coupling for media source devices such as PCs and STBs.

HDMI 1.3 will increase the link's data rate from 165MHz to an expected 275MHz once the new spec is frozen. That paves the way for systems supporting higher resolutions, faster frame rates and deeper color depth.

Some vendors are planning to use the improved data rates for systems with refresh rates of 90MHz or faster. Others are working on systems with 36bit or deeper color depth. HDMI 1.3 will also support the new xvYCC color standard that the IEC released in January.

The new version adds support for Dolby TrueHD and DTS-HD Master audio formats. In addition, it supports a new, automated approach to hiding latency between systems to ensure better "lip synching" of content between systems.

For OEMs, the spec adds a new miniature connector format that is seen as key to easing HDMI more gracefully into portable devices such as notebook computers, camcorders and digital still cameras. A Sony camcorder and a Samsung digital still camera already use the interface.

The group decided to delay approving AC coupling for PCs and other media sources. That would have eased the process of integrating HDMI in the latest silicon process technology, and smoothed the marriage of HDMI and the internal PCIe interconnect.

The group made AC coupling for display devices part of its spec last year. The support for AC coupling on source devices could come "very soon," said Leslie Chard, president of HDMI Licensing LLC, which administers the spec and collects royalties. The fees mainly go back to chip designer Silicon Image, which holds most of the intellectual property on HDMI's underlying Transition Minimized Differential Signaling technology.

About 17 million systems shipped with HDMI in 2005. Three times that many are expected to adopt the interface this year, rising to as many as 278 million in 2009.

Game consoles
Besides DTVs, game consoles such as PlayStation 3 are also adopting HDMI. More than 400 companies have become adopters of the spec.

"If you buy a DTV in the U.S., HDMI is not a high-end feature anymore. It's pretty much become a check box item," said Chard.

One of the teething issues with HDMI has been interoperability. Several reports have surfaced about HDMI links on one system that do not work properly with links on another system or must step down in resolution to do so.

Chard said Intel Corp., which owns the high-bandwidth digital content-protection (HDCP) technology used in HDMI, is developing a compliance program for it. The HDMI group in turn is working with Intel to ensure that the compliance program becomes part of the HDMI use regulations.

HDMI is growing as digital visual interface (DVI) declines. DVI has been used in about 66 million systems this year and will go into about 35 million in 2009, according to market watchers at In-Stat. In part, that's because HDMI supports both audio and video while DVI is only for audio.

But HDMI also faces competition from DisplayPort, a new royalty-free option that aims to leapfrog both DVI and HDMI on several fronts. DisplayPort taps the electrical layer of today's 2.5Gbps PCIe and rides its coattails to bandwidths of up to 10.8Gbps over four channels. It supports lengths of up to 15m while hitting lower voltage levels than DVI.

DisplayPort creates the foundation for a packet-based video protocol for a future 2.0 iteration that would likely be timed with a move to the next-generation 5Gbps Express standard. The packet video approach allows one system to link to multiple displays, eases the job of tiling displays for exhibit, and opens the door to conserving power and bandwidth by refreshing screens only when needed.

DisplayPort also delivers an improved copy-protection schemeone that's incompatible with HDCP, used in both DVI and HDMI. Instead, DisplayPort uses a 128bit encryption key along with AES, rather than the 40bit key used in HDCP. It also adds support for checking the proximity of the transmitter and receiver, a new technique to make sure users aren't fooling a system to send content out to distant, unauthorized users.

The DisplayPort copy-protection scheme will not hit a 1.0 draft until later this third quarter. 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.

Backers including Analogix 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.

- Rick Merritt
EE Times

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