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Ethernet AVB, Promise Fulfilled

It's been a long time coming. Today's Ethernet AVB standard for digital AV networks resembles some of those long-ago platforms that didn't quite pan out.

In the midst of AES's efforts, the excitement generated at the Nashville conference was tempered somewhat when Peak Audio released CobraNet in 1996. The proprietary technology allowed control, monitoring, and multiple channels of digital audio over standard network cabling. It would go on to become as accepted an audio networking protocol as our industry could muster.

But Lone Wolf? When Dave mentioned it, I was flummoxed for a few seconds. Then I remembered. Originally released in 1989 and updated over the next five or six years, Lone Wolf's technology aspired to the lofty goal of becoming the consumer local-area network, carrying everything from home control to video and audio signals over a single fiber. The company went through a lot of money and couldn't bring a successful product to market in a timely manner, which was disappointing to those of us waiting to deploy such a network in the commercial arena. In fact, it was the first (and only) audio network my company considered for the sound systems at Benaroya Hall in Seattle. We reverted to analog systems.

At the time, the promise of a single cable carrying everything set Lone Wolf apart from the competition. True, it offered limited bandwidth (even for fiber), but its potential gave many audio engineers the vapors.

Ethernet AVB promises to have the same effect on audio system designers. However, it turns things upside down for our friends in the IT world. IT managers have been notoriously harsh about allowing digital audio and video on their networks; the bandwidth issues, to them, were too daunting. So why not build network gear that can support multiple audio and video channels, carry control and data, provide high quality of service, and still reserve space for the traffic that a network normally sees? It is, after all, a great way to push the tech envelope and get the IT people to upgrade their switching fabrics, add hardware, and turn a profit.

The AVB formula reserves 25 percent of a 1-Gbps pipe for "normal" network traffic, leaving the other 75 percent to carry the audio, video, and control signals. IT departments might be a little upset over this turn of events, but in the end might have to accept it as inevitable, especially considering Cisco, Broadcom, Xilinx, Intel, and Samsung are founding members of the AVnu Alliance, created to promote the new standard.

Despite the gravitas of this group, a 1-Gbps pipe is barely large enough to fit more than a few compressed H.264 video signals and the necessary audio channels. Fortunately, technology to support much higher bit rates is just around the corner.

So here we are, 20 years later, and it looks as though Lone Wolf was ahead of its time. Even though AVB doesn't look a great deal like Lone Wolf's MediaLink, it should be counted as a direct descendant of that seminal technology. Thus Dave gets his wish. Congratulations, my friend. In your patience you possessed your soul.

Thom Mullins is senior consultant with BRC Acoustics &Technology Consulting in Seattle.



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