SAN MATEO, Calif. A Silicon Graphics Inc. spin-off will unveil this week what it claims is a unique content distribution architecture capable of advancing the industry's dream of delivering broadcast-quality streaming video over the Internet.
Kasenna Inc. (Mountain View, Calif.) is proposing a hybrid system of the "push" and "pull" models represented in edge servers and caching implementations. The goal is a video distribution architecture under which network and content providers can deliver high-quality video when and where needed, while maintaining control over each video asset.
Kasenna's architecture replicates, on edge servers close to viewers, metadata describing each video object's physical characteristics, digital rights and locations on the Net. The approach would allow Kasenna's customers to avoid the high costs of duplicating and storing extensive video files at both core and edge servers.
"Nobody is [now] doing content management and distribution based on metadata," said Satish Menon, vice president of R&D at Kasenna.
The company consists of a team of engineers from the broadband media server division at Silicon Graphics (SGI), who also worked on Time Warner Cable's interactive TV trial in Orlando, Fla., in the mid-1990s. "We are a new startup founded only earlier this year," Menon said, "but we already have more than several years worth of experience in managing and moving broadcast-quality video in video-enabled networks."
Despite Internet users' growing appetite for streaming video, the quality of that experience is limited by bandwidth available in the backbone, the speed of connection, latencies caused by multiple hops between video originations' sites and end users, and packet losses due to congestion of the Internet. In Kasenna's view, neither the edge-server approach implemented by companies such as Akamai, Digital Island or iBeam, nor the caching model pursued by Inktomi, can provide quality broadband video over the Net.
Although caching and streaming edge servers designed to build public Internet bypass networks work adequately, Menon warned that such content delivery solutions are not fundamentally designed to scale for broadband applications.
"Many people underestimate the sheer size of video," he said. They do not allow enough bandwidth in the backbone, and build edge servers without enough storage capacity to handle carrier- and commercial-grade streaming media. "They have no idea how much space broadcast-quality video streams could take up."
Most edge servers are built to improve performance for downloading or streaming small objects, notably images, audio or small video files. Under such architecture, large files today, mostly graphics are stored on servers located closer to users, so that service operators can save bandwidth at the expense of storage. But when today's edge servers are tasked to implement Internet ads with video, Menon predicted, "such a brute-force method usually won't work."
Delivering personalized information such as news, sports and entertainment on demand will be traumatic for most service providers, Menon said. "A five-minute video segment at 1 Mbit per second amounts to 37.5 Mbytes. One such channel of video, a 24-hour segment split into five-minute segments, amounts to about 10 Gbytes of storage. A hundred such channels amount to 1 Tbyte. Such media stored on 1,000 edge servers amount to 1 petabyte of storage." (A petabyte equals 1,000 terabytes.) "And please note," said Menon, "that we are just talking about one day's worth of video here."
Under the caching scenario, meanwhile, media is cached only on servers where they are actually used. The drawback is "long startup delays," said Menon. "Timing could kill the usage."
He also cautioned that media, once cached, cannot be easily tracked for viewer usage. "The loss of tracking ability makes it difficult for service providers to create revenue via targeted advertisement," he said.
To avoid the timing issue prevalent in a conventional caching model, Kasenna will use a technique it calls "prefix caching," which enables edge servers to start streaming video to viewers immediately, without waiting for central servers to deliver video over the congested public Internet.
With this technique, small "video leaders" come included with the metadata describing video assets. When a user requests a video URL, the video leader instantly begins streaming. The remaining video content is simultaneously fetched in parallel and cached.
Kasenna will also provide video content distribution software that tracks, reports, bills and targets advertising.
With industry groups like SMPTE and the TV Anytime Forum developing their own versions of metadata, Kasenna has no plan to duplicate the task. "We hope to use the industry-standard metadata most suitable for our applications," Menon said.
The startup plans to unveil further details of its end-to-end broadband video delivery platform later this year.
Since spinning out of SGI, Kasenna has got its software up and running on a range of popular operating systems for the broadband Internet: Sun Solaris, Intel Linux and SGI Irix.
Initially staffed by 30 SGI engineers, Kasenna now has about 80 employees and expects to grow to 100 by the end of this year. The company was formed with funding by U.S. Venture Partners, Alloy Ventures, Entertainment Media Ventures and SGI.