Audio Routers: Bigger, Better, and in the Center of Things

That audio routers continue to grow more powerful with each generation is no longer news. What is news is that their status is evolving from peripheral to core platform in dense, complex, and high-I/O-count audio networks.

One reason for the router’s growth is the increasingly networked nature of broadcast-sports audio, which has to cover events on ever wider scales every year. The sprawling X Games franchise, for example, is a large part of what’s behind ESPN’s massive matrix at its Bristol, CT, HQ, where Stagetec’s Nexus routers host what the manufacturer estimates is a 20,000×20,000 I/O matrix.

Also, the sheer number of microphone and line-level inputs used for events continues to rise, with 5.1 the norm for sports and 7.1 waiting around the corner.

“Routers used to be implemented at the independent level. That is, you’d have separate routers for audio, for video, for control,” says Paul Greene, product manager for routing switchers at Harris Corp. “Now all that processing is moving to a single router platform.”

The use of audio embedded into the video signal has propelled this evolution, he says. The need to reconfigure embedded audio tracks as they are ingested into a facility — to conform to a plant’s track assignments or for language changes and other functions — has meant that routers can now serve as the entire frontend of a broadcast facility.

Greene points out that, with a relatively new frame-synch card on Harris’s Platinum router, users can re-embed audio to video before the signal reaches the crosspoints. “That used to be a process that involved several moves, and it’s now all done within the core of the router itself,” he says. “The great thing is that it’s also scalable: you can get that kind of functionality in routers of all sizes.”

The emergence of the router as the processing core for audio suggests it will rival or supplant the audio console as the hub of the broadcast-audio system. “In a single-room [studio] situation, the console is still the center of the action, for I/O and processing, but, as soon as you’re working in a multi-room, multi-location situation, the router becomes critical,” says Rusty Waite, president of Stagetec U.S., which makes both the Nexus routers and audio consoles.

He views the developing relationship between these two product categories as one where the console becomes a work-surface extension of the core router. “In an environment where you will routinely have to embed and de-embed 16 channels of audio for 80 separate video signals,” he asserts, “the router has to become the central processing engine.”

Herbert Lemcke, president of Lawo North America, which also makes both types of products, doesn’t disagree that the router and console have become more integrated but says that it has been headed in that direction for a while, a consequence of ever larger I/O needs that consoles alone could not handle.

“In a way,” he explains, “the router is a subset of the console: the hardware between the router and the console is identical, and the software is closely related.” Increasingly, he adds, consoles and routers are sold as packages.

New Functionality
Underscoring this heightened status, the router is taking on functionality that used to be assigned to consoles or other key control-room platforms. For instance, new this year at the NAB Show, Stagetec added a loudness meter to the Nexus; last year, Harris added a multiviewer to its Platinum router.

Keith Bond, VP of product management at PESA Switching Systems, believes that AV routers is a rapidly matured category that will increasingly rely on features for product differentiation. He points out that PESA’s Cheetah DRS Series distributed router uses high-speed multiplexing technology for signal distribution rather than a crosspoint matrix array. Each 1RU I/O frame provides 128 signal ports, with interconnections made using Cat 5E cable and standard RJ-45 connectors.

“I think we’ll start seeing some [AV] routers begin to look more like data routers, where they become essentially a network appliance,” he suggests. “But synching audio and video through a data router is a tricky thing.”

Lawo’s Herbert Lemcke agrees that the IT paradigm will be increasingly familiar to audio-router users. Already, the company’s redundancy architecture echoes what is seen in large data router installations: proprietary dual self-healing star (DSHS) configuration is an improved dual-star architecture in which a single-point failure in the I/O frames will not cause a complete core takeover.

Integration of new digital audio formats will also be key to router evolution. “Audio-over-IP is going to be very important moving forward,” says Lemcke.

Basics Still Important
But the basic trends of router application also continue to be compelling. “Power, size, and weight” are the fundamentals of router applications in trucks, says Steve Dupaix, director of product management for routers and signal management at Grass Valley. The fact that all three continue moving in the right direction — up, down and less, respectively — means that the ability to embed/de-embed audio with video within the router itself can be brought to the truck level win the form of smaller, lighter routers.

“A lot of companies are now using MADI [transport] for that,” he explains. “Our Apex router, for instance, takes a loop-in/loop-out approach that uses additional outputs to take video signals out for [external] processing, then send them back in for embedding with audio again,” all within the remote-truck environment. “Anything that lets you pull racks of equipment out of the truck is a good thing for sports broadcasting