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Completing The Big Picture Of The Audio Video Bridging Protocol

With the IEEE 802.1 Audio Video Bridging (AVB) Task Group working steadily toward the finalization of a fully interoperable protocol that builds and improves upon the ethernet transport, the introduction of the first new products to implement the next-generation audio and video networking standard moves ever closer. Until that standard is in place, manufacturers offer plenty of alternative ethernetbased digital audio distribution methods.

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Aviom Allframe Multi-Modular I/O System

Yamaha Commercial Audio Systems supports a broad range of audio network options, perhaps more than any other pro audio equipment manufacturer. “We’re a lot like Switzerland; our deal is that we speak any language,” agreed Steve Seable, the company’s DSP/network manager. “Through our MY card slots we’ve got a lot of flexibility. As far as networking, with products we distribute we support CobraNet, EtherSound, and Dante. But there are also cards available that we don’t distribute, for Optocore, [Media Numerics’] RockNet, and [Aviom’s] A-Net.”

According to Ethan Wetzell, global product manager for Electro-Voice signal processing, DSP, and software, the pro sound division within Bosch Communications Systems currently supports two audio transports: “We’ve been using CobraNet for a number of years in the NetMax product line. At InfoComm this year we also made the announcement that we are releasing a Dante network card with the NetMax system.”

CobraNet has been one of Harman International’s audio transport of choice for about 10 years, according to Adam Holladay, Senior Market Manager, System Development and Integration Group. It was adopted first by Crown, then BSS Soundweb London, and most recently for JBL powered line array and installed sound loudspeakers.

Harman was one of the six founding promoter members—along with Samsung and silicon manufacturers Broadcom, Cisco, Intel, and Xilinx—of the AVnu Alliance, which was established in August 2009. The group, which has since expanded to 27 members, is working to develop AVB compliance and interoperability specifications, and offers product certification.

“We’ve long worked to make HiQnet the configuration and control protocol of choice and whereas we previously coupled it with various transport protocols like FireWire or CobraNet depending on the application, we’re now firmly of the belief that AVB is the singular way forward. Look closely at cost-per-node, video capabilities, ease of deployment and AVB wins hands down,” Holladay said.

When ethernet was invented, the objective was simply to transport data reliably from point A to point B, noted Lee Minich, AVnu Alliance marketing workgroup chair and president of Lab X Technologies. For typical applications at that time, it didn’t matter if data was retransmitted or held up in a buffer, but the scheme’s limitations make it less suitable for AV applications 30 years later. “Those basic shortcomings in ethernet were that there were no mechanisms for synchronization and distributing time throughout the system; for an automatic mechanism to reserve bandwidth, because media inherently needs a timely delivery versus downloading email or a webpage; or for traffic shaping, so that it behaves nicely,” said Minich.

Proprietary ethernet-based protocols have an additional issue he said: “They’re proprietary, and that usually necessitates a particular business model, which makes it somewhat more expensive and usually royalty-based for a manufacturer to incorporate.”

The big semiconductor manufacturers saw that people had to work around these restrictions, continued Minich. “Instead of trying to put a Band-Aid on it they asked the question that nobody else really had asked: If there are shortcomings with ethernet, why don’t we change and augment ethernet?”

Harman is firmly behind the protocol. “We’re very keen to do whatever we can to make it the future of the AV industry as a whole,” Holladay said. “Harman has had a team of engineers working along with Broadcom and the developers of the protocol to make it real for the industry, and us, and ensure that the promise of it being able to revolutionize the pro AV industry is realized.

“Over a period of at least a couple of years there will be a staged introduction of Harman AVB products, beginning with one each from BSS, Crown, and dbx,” Holladay revealed. “Our customers aren’t going to switch to AVB overnight.” With a consumer AVB market still to emerge, Harman’s distribution deal with NetGear for its AVB-capable switch will ensure that this essential component is available.

As regards to video, he added, “The digital signage market and information-based systems would be an obvious first step for traditionally audio-only manufactures to begin to blur the lines with the ‘V’ part of AVB.”

At least one manufacturer wants to see the final AVB standard before jumping on the bandwagon. Dante was a couple of years old before Yamaha adopted it, Seable pointed out. “There are a couple of things that still haven’t been answered about AVB,” he said, in particular patching. Whereas Audinate, Cirrus Logic, and Digigram created patching software for their respective protocols, someone may need to turn over their software, and associated R&D time and money, for AVB to work similarly, he contended.”

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BSS Soundweb London BLU-800 And BLU-160

But, Seable added, “Dante is just a firmware upgrade to AVB. If [AVB] seems to be taking off we’ll be ready to take advantage of it.”

Bosch, also an AVnu Alliance member, recognizes AVB’s potential for simplifying system design and integration. “We’re very cognizant of audio systems being just that they’re systems. I think one of the key things to keep in mind is how we manage the overall system, the network architecture, the communications and the paths. That’s where AVnu and the AVB standards and protocols are taking a step in the right direction,” Wetzell said. “We’re reaching the point in the industry where we’re starting to put more focus back on ease of use and ease of integration; I think that’s really key. If you have all of these wonderful things that it’s flat-out too difficult to configure or make use of, it’s not going to do you any good.”

Holladay agreed: “It’s enabling us to change the way the system designer interacts with the network technology and really simplify it. We’re trying to think less about devices and think more about the behavior of the installed sound venue, and be able to route audio across the geography of a physical venue.”

Steve Harvey (psnpost@nbmedia.com) has been west coast editor for Pro Sound News since 2000 and also contributes to TV Technology and Pro Audio Review. He has 30 years of hands-on experience with a wide range of audio production technologies.

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