Methods differ for boosting video

By Jason Meserve, Network World |  Software

Like caching vendors attempting to speed the delivery of standard Web pages, Kasenna and start-up Vividon, Inc., are looking to improve the quality of IP-based video by providing systems for ISPs to move content closer to the edge of the network.

The premise behind the companies is similar in that both are looking for ways to distribute content away from a central origin server, moving that content closer to the end user requesting it.

Unlike e-mail or text, video is highly affected by the number of network hops between origin and destination. More hops mean greater latency and an increase in the number of dropped packets, resulting in a degradation of video quality. Streaming media requires a consistent latency time and minimal packet loss to maintain a quality experience. Pushing delivery closer to the end user is critical in reducing hops and in turn, lowering the likelihood of dropped packets.

"End users want television-quality video so [content providers] have to get close to MPEG-quality video for people to watch on a large-screen display," says Walter Miao, vice president of Probe Research in Cedar Knolls, N.J.

"[Good quality] video requires 300K bit/sec of bandwidth, and most backbones only provide an average of 60K bit/sec" from origin to end user, says Neil McGowan, vice president of Kasenna.

Although most backbones are fat pipes, the number of hops and the latency reduces the effective bandwidth for video to around 60K bit/sec.

Although both companies build products for content delivery, Kasenna and Vividon differ greatly in their approaches.

Kasenna of Mountain View, Calif., unveiled its software-based Video Content Distribution (VCD) product at Streaming Media Europe held last week in London. Vividon, of Sudbury, Mass., is still in the early testing phases of its rack-mounted hardware-based Content Delivery Server.

Kasenna's approach to content delivery is slightly different than the usual store-everything-at-the-edge strategy. The company instead stores metadata describing the type, size and location of the video clip and a small leader of the video at the edge, leaving the rest at the origin. When a user requests data from a local Kasenna server, the leader is sent immediately, with the remainder of the video coming from the origin.

"Most content delivery networks [CDN] do central storage and use algorithms to push out content to the edge," Kasenna's McGowan says. "For large video files, CDNs would incur large storage costs to [keep] all the content at the edge. We can cut the storage at the edge by 90%."

Kasenna has also designed its software to run on Linux, Solaris and SGI Irix (the company originally spun out of SGI), giving ISPs and content-delivery networks a choice of platforms and hardware types.

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