The Comcast Media Center (CMC) conducted a bakeoff this week to evaluate technologies that might eventually pack four MPEG-2 high-definition feeds into one 6MHz-wide channel, Light Reading Cable has learned.

The Colorado-based CMC declined to comment on that work, but it's believed that the Comcast unit is already tapping equipment from Imagine Communications and Harmonic Inc. (Nasdaq: HLIT) to deliver some HD channels via a 3:1 compression scheme.

Freeing up space for another HD feed could let the CMC beef up its hi-def content menu or allow its MSO partners, including Comcast Corp. (Nasdaq: CMCSA, CMCSK), to free up capacity for other digital services, such as video-on-demand or 3DTV channels.

An industry source said the bakeoff included participation from Arris Group Inc. (Nasdaq: ARRS), BigBand Networks Inc. (Nasdaq: BBND), Harmonic, and Imagine, among others. Those are well established cable suppliers, but, of recent note, Arris boosted its video technology profile through its acquisition of EGT Inc. and has recently talked up the 4:1 HD capabilities of the EGT VIPr2200 encoder. (See Arris Offers 4:1 HD Compression and Arris Gets EGT for a Song .)

Although the CMC is starting to take a closer look at 4:1 HD, there's no timetable for deployments. Multiple sources say a migration in that direction may not occur until next year, and that's if the technology proves itself worthy. Even if it does, it's considered unlikely that the CMC would use the 4:1 compression techinique for all the HD channels it carries.

A priority of that evaluation will be to ensure that the feeds can be squeezed down while also preserving the quality of the HD signal, minimizing artifacts and other elements that can negatively affect the image.

Some heat was put on Comcast in 2008 when a consumer in Virginia negatively compared how some of Comcast's compressed HD channels fared versus those delivered by Verizon Communications Inc. (NYSE: VZ) FiOS TV. The blame was largely pinned on Comcast's use of 3:1 HD compression for MPEG-2, but a person familiar with the situation says the channels referenced in that study weren't delivered in that way. However, the compression used at the time on the channels studied were squeezed down to the point that it did have a noticeable effect on the picture quality.

It appears Comcast has gotten a grip on those issues since and has implemented a range of projects to ensure that video quality is up to snuff. The CMC, for example, has launched a Golden Eye program in which "trained observers," who are able to detect small imperfections in video that most other consumers can't, provide subjective video quality ratings. That program is part of a broader grading system the CMC has developed for digital video quality, as described in a white paper presented at the 2009 Cable Show in Washington, D.C.

— Jeff Baumgartner, Site Editor, Light Reading Cable