Toshiba Hdtv

LAS VEGAS--Transmitting DVD and HDTV video streams over a wireless network connection has become something of a holy grail in the consumer electronics business. Video-over-wireless has been talked about in the PC industry for a long time, but progress has been somewhat desultory. After all, PCs are often on wired networks, so wireless delivery of content wasn't quite as critical.

However, as new content-delivery technologies begin showing up in the home, consumers want to be able to view or hear their video or music anywhere in the home. Many consumers have no desire to spend the dollars needed to string wire through the house, so are looking at wireless solutions to facilitate their entertainment addictions. So a number of companies have popped up to try to address the thorny issue of delivering DVD quality and even HDTV quality video streams over wireless networks. Some, like Magis, have adopted a proprietary approach, designing their own network stack. This allows them to build in network-based quality of service. The downside is that most companies feel uncomfortable with single-source, proprietary technologies.

Toronto-based ViXS Systems thought about the entire quality-of-service issue, and came to the conclusion that a steady frame rate is the real key. Consumers might put up with a slight or occasional softening of the image quality, but perceive jerky or dropped frames as a much more serious issue, even if the other frames look perfect.

To that end, ViXS developed a bipartite solution. The first part is the Xcode II, a chip that will encode and decode video and audio streams on the fly, convert (transcode) them to a convenient (but standard) format and ship the stream over the wireless network. The Xcode II supports MPEG4 level 5 ASP and MPEG2 (up to 720x480 resolution for NTSC). The part is also programmable, and can support other video standards through software. The processor can transcode four simultaneous video streams.

The second part of the solution is the Matrix, an 802.11a Baseband processor that can move multiple streams simultaneously over two 802.11a channels. Using 802.11a avoids potential conflicts with consumer PC wireless (typically 802.11b or 802.11g), 2.4GHz cordless phones and the ubiquitous microwave oven.

The real key is the ability to monitor the data rate over the network, and vary the bit rate of the encode step on the fly. The goal is to maintain a constant frame rate while adjusting the bit rate to address networking issues. Although the image may soften somewhat on occasion, the eye often doesn't notice this as readily as if frames had been dropped. When the network recovers to a higher throughput the bit rate of the transcode increases to the full bit rate.

It's an interesting solution that's gaining some traction among Asian manufacturers of TVs and media adapters. Companies like Nexgen, Daewoo and Gemtek will be building products based on ViXS technologies. The largest announced relationship to date is one signed recently with Toshiba, who is looking to build wireless PVR products based around the Xcode II. Look for products to arrive on U.S. shores later this year.

For more, check out PCMag.com's 2004 CES Special Report at CES.PCMag.Com.

Copyright © 2004 Ziff Davis Media Inc. All Rights Reserved. Originally appearing in PC Magazine.

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