BigBand Networks Inc. (Nasdaq: BBND) has slapped Imagine Communications with a lawsuit alleging that the startup, which employs several ex-BigBand execs, has infringed on three patents covering advanced video processing and techniques designed to conserve precious cable bandwidth.

The suit, filed this morning with the U.S. District Court for the District of Delaware, claims Imagine is infringing on three patents: 6,937,619; 6,999,477; and 7,058,087.

Table 1: BigBand Patent Trio

BigBand is seeking an injunction against Imagine and unspecified damages.

Imagine -- based in Cardiff by the Sea, Calif., and founded in 2005 -- is developing a variable bit rate (VBR) platform that promises to increase a cable operator's bandwidth efficiency by 50 percent for video-on-demand (VOD) and switched digital video (SDV) applications.

By employing VBR -- a technique that changes bit rates on the fly -- the company believes it can cram 15 standard-definition streams into one QAM channel, versus 10 streams using fixed, constant bit rate (CBR) technology. The efficiency also applies to high-definition television. Imagine says its system allows for three HD streams (rather than two with CBR) to be squeezed through the QAM.

As the idea goes, the number of bits allowed through the system correlates to the intensity of the video. A football or hockey game would require more bits than a newscast full of talking heads, for example. Imagine's architecture calls on a Quality on Demand (QOD) Processor to pre-process the video, while an edge device, called the QOD Gateway, reassembles the video and metadata before they are delivered to the home.

In announcing its complaint, BigBand points out that five of its former execs are employed by Imagine: Imagine president and CEO Jamie Howard; chief technology officer Ron Gutman; vice president of engineering Doron Segev; VP of Sales Brian Bentley; and VP of engineering for network systems and support Mark Davies, who was named to the post yesterday.

BigBand's general counsel, Rob Horton, described all five as having "access to our IP during their work at BigBand."

An Imagine spokeswoman declined comment, as the company was still reviewing the lawsuit. Imagine has 30 days to file a response, according to Horton.

The timing of the lawsuit is a bit unusual given that Imagine has yet to score much in the way of trials or deployments, and is, therefore, unlikely to have much in the way of revenues coming in the door. In May 2006, it announced the completion of a $9.2 million first round of venture funding led by Carmel Ventures and Columbia Capital .

Horton says BigBand has been building its case for some time, and the move into material litigation marks the first for BigBand, which went public in March. (See BigBand IPO: Boing!) BigBand says its switched digital video technology is deployed to cable systems passing more than 6 million cable homes.

"It's not an enjoyable thing, but we have to protect our IP at the end of the day," Horton says of the lawsuit.

When Cable Digital News last checked in April, Imagine said it was "deep into lab trials" with two major, albeit undisclosed, U.S. cable MSOs. (See Imagine Imagines Success.)

One of those could be Comcast Corp. (Nasdaq: CMCSA, CMCSK). Speaking at an analyst and investor day on May 1, Comcast chief technology officer Tony Werner alluded that the operator was exploring the bandwidth efficiencies afforded by variable bit rate VOD, the technique central to Imagine's platform. (See Comcast Preps Docsis 3.0 Trials.)

Imagine has made more progress in the form of key integration deals with established VOD server and backoffice software vendors, including SeaChange International Inc. (Nasdaq: SEAC) and Tandberg Television . (See Imagine Connects With SeaChange and Imagine, Tandberg Hook Up.)

— Jeff Baumgartner, Site Editor, Cable Digital News