Multipoint HD video conferencing bridges: Capacity vs. quality

Is there a tradeoff between capacity and quality with HD video conferencing bridges? Some vendors say yes, but IT pros must take a broader perspective on multipoint video conferencing.

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Some vendors claim that enterprises will trade quality for high capacity when they deploy high-definition (HD) video conferencing bridges, but IT professionals have found that tradeoff to be more nuanced. When evaluating multipoint video conferencing infrastructure,

Quite frankly, I like the simplicity of the [fixed capacity] bridge.

Scott Aldridge
Advanced Technologies Specialist
U.S.-based engineering firm

 they must take a broader strategic perspective and consider pricing, future demand and the availability of in-house expertise.

"[Enterprises] look at price, and they look at building very lightly oversubscribed or non-oversubscribed capacity [for] their use case," said Robert F. Mason, research director at Gartner Inc. "If you've got 13 endpoints at your sites, and 13 endpoints is the biggest you're going to get, all of a sudden a 15-port bridge looks pretty good."

Vendors approach HD bridges for multipoint video conferencing from two philosophies, Mason said -- fixed versus dynamic capacity, sometimes referred to as "port-is-a-port" versus "flexible resource management." Fixed capacity HD video conferencing bridges only support as many calls as the number of ports they have. Dynamic capacity bridges are more fluid and can accommodate more or fewer calls based on the processing power consumed by endpoints' display resolution.

Vendors with fixed capacity bridges say competitors sacrifice quality for capacity; dynamic capacity vendors fire back that their approach is more scalable and that advancements in the technology mean that quality is no longer compromised.

"There is a trade-off and to some extent … the use case [dictates] how much you're going to see the trade off," Mason said.

Enterprises that have large, global and heterogeneous deployments and have in-house bridging specialists will likely prefer the dynamic model, he said. Small and medium-sized businesses (SMBs) with single-vendor environments and little HD bridging expertise often prefer the straightforwardness of a fixed model, Mason said.

Favoring the simplicity of fixed capacity multipoint video conferencing

Advanced technologies specialist Scott Aldridge found the lower price and simpler management of a smaller, fixed-capacity HD video conferencing bridge more appealing than the benefits of more advanced models.

"I didn't like the price on the [larger dynamic capacity] ones and they were too complicated … [because] you have to figure out, 'Am I using four ports for this call or two?' and use software to manipulate it," said Aldridge, who works for a U.S-based engineering firm. "Quite frankly, I like the simplicity of the [fixed capacity] bridge."

Aldridge recently spent a month beta testing Logitech LifeSize's first external multipoint HD video conferencing bridge, the Bridge 2200, which has a 16-port fixed capacity. LifeSize had traditionally built four-port and eight-port HD bridges into its endpoints and resold original equipment manufacturer (OEM) Radvision's 24-port HD bridge, Multipoint24.

Aldridge also evaluated HD multipoint video conferencing bridges from Tandberg and Polycom, as well as the Multipoint24 from LifeSize in his all-LifeSize environment. He plans to purchase two of LifeSize's new HD bridges for his data centers. In addition to a lower price and easier management, when compared to the rest, the 2200 was "far superior for its clarity and quality," he said.

Even with increased demand and plans to double his 30-endpoint implementation over the next year throughout his firm's 120 global locations -- 25 of which now house HD video conferencing systems -- Aldridge said that he doesn't expect to be burdened by stacking too many boxes, sometimes referred to as "cascading."

"I think the 'wow factor' of having 16 offices connected [on a simultaneous call] is nice, but I don't think we'll ever have practical uses [beyond] 10 or 12, because it gets too unwieldy," he said.

Encouraged by the 2200's price, quality and performance, Aldridge said he would purchase more of them as his bridging needs grow and he will deploy them across multiple sites for load balancing. The smaller internal bridges built into LifeSize's endpoints may also help offset call traffic, he said.

He suggested that LifeSize should release firmware updates to enable dispersed bridges to be managed from a central console.

"In the short term, I will set the MCU [multipoint conferencing unit] affinity for each of our endpoints to use the 2200 geographically nearest to them to handle calls, thus balancing the load around as needed," he said. "I'm looking at this as a good start and expect more features and functionality to be built into them as time goes on."

Capacity vs. quality HD video conferencing bridge debate: Is it 'antiquated'?

Dynamic capacity bridges that let frame rates drop to 25 frames per second (fps) to accommodate more callers are going to cause pixelation and compression artifacts, according to Travis McCollum, product manager at LifeSize. LifeSize claims that its bridges don't drop below 30 fps.

That may have been the case years ago, but technical advancements in multipoint video conferencing make the capacity vs. quality approach a "really antiquated way to think," according to John Antanaitus, vice president of product marketing at Polycom.

Polycom's multipoint video conferencing infrastructure line, the RMX series, adjusts its processing power to accommodate and optimize more callers, Antanaitus said. For every HD 1080p at 30 fps endpoint that dials into Polycom's RMX 1500, the bridge can support four standard-definition 4CIF (Common Intermediate Format) calls or two HD 720p at 30 fps calls. The platform sharpens the image of, and otherwise improves the display from, lower-quality endpoints, Antanaitus said.

"We understand that [fixed capacity] is a simple message, but the reality of the world is [that] it's not as simple and homogeneous," he said. "When you have a port-is-a-port solution [and] 16 [endpoints] optimized for high definition, then that's great … but you're wasting DSP [digital signal processing] resources in the bridge if you're calling it with standard definition or something less."

Let us know what you think about the story; email: Jessica Scarpati, News Writer

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