Sound Connections in Audio Networking
The world of networked AV is its own kind of Babel. CobraNet, developed by Peak Audio in the mid-1990s and the first successful digital audio networking protocol, had a shot at becoming an industry standard. But while its acceptance by the pro audio industry was fast, it wasn't fast enough to outpace a host of other companies. We look at four of today's prominent protocols.
The world of networked AV is its own kind of Babel. CobraNet, developed by Peak Audio in the mid-1990s and the first successful digital audio networking protocol, had a shot at becoming an industry standard. But while its acceptance by the pro audio industry was fast, it wasn't fast enough to outpace a host of other companies that thought they had an equally good chance at developing their own widely accepted digital audio networking solutions.
By the turn of the century there were nearly a dozen proprietary networking protocols on the market, each vying for broad acceptance by various sectors of audio, from live to installed sound. The implementation of some, by vertically integrated companies that could make their own mixers, loudspeakers, DSPs, and other audio products more intimately compatible with their particular protocol, helped cement the Balkanization of the nascent networking sector.
However, the diversity of protocols fulfills the same kind of need that diversity in the biosphere does. "They all have their strengths and weaknesses," says John McMahon, currently executive director of digital products at Meyer Sound and who, when at LCS Audio (which was acquired by Meyer in 2005), was one of the first to employ CobraNet. "Some work very well for low latency on dedicated networks, others have higher latency but use lower bandwidth, which works well for existing IT infrastructure."
Few would argue that networked solutions are the way to go for AV distribution. We look at four prominent protocols.
Pros: Supports multiple sample rates and latency modes in a standard Ethernet network design and coexists with other network applications.
Cons: New product introductions have slowed as manufacturers opt for more updated technologies. It doesn't scale beyond local area networks (LANs) and utilizes 100-Mbps devices only, with a maximum 32 channels to any connection.
Suitable Applications: Convention centers, theme parks, airports, churches, digital snakes in touring sound, legislative applications, live theater.
CobraNet is the most established of the digital networking contenders. It's been around since the mid-1990s and is the most widely used technology for audio over Ethernet. It delivers audio in standard Ethernet packets over 100 Mbps, switched Fast Ethernet on Cat-5 cable at a distance up to 100 meters, or up to 80 kilometers over fiber. It's fully compliant with the Institute of Electrical and Electronics Engineers' (IEEE) 802.3u specification and all similarly compliant switches.
The brains of CobraNet are now developed by chipmaker Cirrus Logic, which offers royalty-free versions that provide two, eight, or 16 full-duplex channels of audio input and output at configurable network sample rates of 48 and 96 kHz and sample sizes of 16, 20, or 24 bits. Control, monitoring, and management functions are provided by a high-speed parallel host processor interface or via Ethernet using industry standard Simple Network Management Protocol (SNMP).
There are versions of the CobraNet audio technology that add 32-bit signal processing, as well as interface modules that support up to 32 full-duplex channels of audio (though the latter requires a license).
Audio pros say CobraNet's advantage is its ubiquity. "You can find more products with a CobraNet interface than any of the others," says Kevin Gross, an independent systems consultant. "This means many choices as a system designer and a lot of knowledge and expertise out there. It also means that even if it is getting a bit long in the tooth, it is likely to outlive some of the newer technologies."
Recently, a major $116 million, 407,500-square-foot expansion project at the Oregon Convention Center required an AV upgrade that could flex with the facility's highly configurable wall systems and integrate with its existing infrastructure. Integrator Delta AV chose to create a CobraNet network over a LAN, incorporating audio, video, and control in any configuration. The audio was based on Biamp's Audia platform, which handles systemwide signal processing and routing, and is distributed via CobraNet using QSC's RAVE multichannel router.
The project began several years ago, but Jeff Overbo, project manager for Delta AV, says CobraNet would have been the network of choice had it started last week, citing his firm's familiarity with it and the network's ability to scale easily. "We had experience and a good track record with it in complex applications," he says. The audio in the convention center is limited to paging, announcements, background music, and other types of low-bandwidth content, which Overbo says fits CobraNet well. "It's probably not the best choice for a high-quality music system because of latency," he explains.