WiFi Faces Video Challenger
Version 1.0 of the Wireless Home Digital Interface (WHDI) specification gets announced today, promising an open-specification 5GHz technology that can deliver bandwidth far exceeding what WiFi delivers. Whether that's truly useful is up for debate.
WHDI comes from the people who first promoted the HDMI (High-Definition Multimedia Interface) for connecting HD gadgets to the television, and its key sponsor is chipmaker Amimon Inc. , which provided much of the technology for the spec.
It's got the backing of some big consumer-electronics names, including Motorola Inc. (NYSE: MOT) and Sony Corp. (NYSE: SNE).
It's also been a while in coming. Amimon was founded in 2005 to probe this problem, and the WHDI Consortium had at one point hoped for a specification in 2008. (See Wireless HD Group Forms.)
The most basic use of WHDI is to replace the HDMI. In that respect alone, the standard could be a roaring success: Who wouldn't be happy to never deal with that cabling again?
But if WHDI backers have their way, the technology could go beyond that, to cover all devices in the home -- PCs, in particular. The key there is the use of 5GHz spectrum, as opposed to the 60GHz range preferred by other HDMI replacement standards.
"The performance is similar to WiFi: 100-plus feet through walls," says Leslie Chard, vice president of marketing for Amimon and president of WHDI LLC, the Amimon subsidiary in charge of licensing the standard. (Chard also helped create HDMI, back when.)
The performance might be there, but winning the hearts of vendors might take time. Amimon's chips are being used for some professional video devices and medical equipment, but for the home networking idea to work, the company has to crack the TV and PC markets.
Meanwhile, WiFi is already in every PC and has begun to infiltrate home networks for HD video delivery. Ruckus Wireless Inc. , for instance, has won over some notable European carriers in that regard and has managed to convince AT&T Inc. (NYSE: T) to make WiFi an option for U-verse customers' home networks. (See DT Picks Ruckus Wireless, PT Picks Ruckus Wireless, SingTel Picks Ruckus, Raising a Ruckus With U-verse, and AT&T's U-verse Gets Ready for Ruckus .)
That adds up to WHDI being a "nonstarter" for home networking, says David Callisch, Ruckus's vice president of marketing.
"It's going to require new silicon on the sending device and on the receiving device, and it's going to be expensive silicon that's going to have to compete with home WiFi," Callisch says. "People don't want two competing networks in the house. The good application for it is behind the TV."
How can WDHI battle WiFi? The spec does have nifty features, such as a means of prioritizing the most visually significant bits of a video stream. It's like a miniature quality-of-service function that, ideally, relegates any glitches to the parts of the picture that aren't changing anyway.
But the main battleground will be over whether there's a need to be sending uncompressed HD video around the home. That would require speeds in the gigabit range. WiFi can't get there, but WHDI claims speeds up to 3 Gbit/s.
The question has less to do with bandwidth than with what form the video is in. In transmitting video from a laptop to a TV screen -- a (legally) downloaded movie, for instance -- the typical user won't want to install codecs on the TV so that it can receive a compressed stream, Chard says. Similarly, he says applications might arise where video is to be treated before arriving at the TV (by having the set-top box insert targeted ads, for instance), and that work has to be done after the video has been uncompressed.
Unless enough of those situations arise, though, compressed HD video could remain good enough. It only requires 20 Mbit/s in the case of MPEG-2 compression and 12 Mbit/s for MPEG-4 compression -- numbers that 802.11n WiFi can handle
As often happens in these situations, Chard insists his new technology can coexist with what's already out there. He's thinking that eventually, one 5GHz chip will handle both WHDI and WiFi, letting equipment use whichever standard is appropriate for a given task.
And while it's true that PCs don't have WHDI, Chard notes that PCs didn't use to have HDMI connections either -- and now they do, testament to the demand for using PCs as HD video devices, he says.
— Craig Matsumoto, West Coast Editor, Light Reading