Cable Further Compressing HD Channels

One of the hotter HD-centric topics circulating around the Internet in recent days centers on an informal measurement of compression regarding Comcast and Verizon HD services, conducted by an HD enthusiast who does not work in the communications field (and therefore has no ax to grind).

The blogger, Ken Fowler of Arlington, Va., noted on AV Science Forum that while watching identical material fed simultaneously on both Comcast and Verizon, he noticed the Verizon FiOS (fiber) carriage was noticeably less compressed than Comcast’s channel.

He noted that image quality (especially in action sequences) often was inferior to Verizon’s HD channels airing the same content, although he found that some channels—notably ESPN and the major broadcast networks (via local HD broadcasters in the Washington, D.C., market)—did not appear to have been degraded via compression.

Comcast, for its part, has readily acknowledged that where it used to divvy up each channel (roughly 6 MHz) into two HD signals, it’s now dividing each into three HD venues, according to The New York Times. (Time Warner Cable is also now doing this three-way split, according to The Times.) Comcast said while virtually all cable and DBS systems compress their channels to varying degrees, Comcast’s goal is for its compression schemes to not be noticeable to the typical viewer.

Terrestrial direct-to-home HD broadcast signals typically are not compressed, putting them in a league of their own that appears to be getting more noticeable, so to speak, as other HD channels become increasingly compressed.