Cable HD not so high-def, say subscribers

Some cable providers, most notably Comcast, are receiving even more flak over the quality of their high-def programming. The problem has been getting HD signals to fit in the given bandwidth, and now it may be taking a toll on quality.

While it may not be noticeable to the average television viewer's eye, some home theater enthusiasts are saying that Comcast's picture quality is not up to par. Now, recent tests by enthusiasts are backing up those observations with hard evidence.

In a post to the AV Science Forum, Ken Fowler ("bfdtv") found that bitrates for HD channels provided by Comcast were as much as 38% lower than that of Verizon FiOS.

FiOS is generally used as a benchmark as its HD signals are not compressed by Verizon before being sent to customers. The tests were conducted at Fowler's home in Northern Virginia.

"This is an absolute shame. I used to not mind paying Comcast's high prices because their HD quality was so good," Forum member Joseph McKinney wrote in response to Fowler's post. "I have also noticed a significant degradation in HD quality. I will immediately jump ship when FiOS comes to metro Detroit."

While some channels are not as bad -- HBO HD only differed by 0.7% (8.87 to 8.81 Mbps) from Verizon to Comcast, and Food Network by 4.3% (14.32 to 13.73 Mbps), it gets worse from there.

Some of the worst offenders here are the Discovery Network channels: Discovery HD by 35.8%, and HD Theater by 38.5%. Other networks are as equally bad: A&E HD by 28.9%, and Starz HD by 22.2%.

Much of the problem here could be Comcast's need to add more channels to its high definition lineup. It recently began to use new technologies which compress the signal of three HD channels into the same bandwidth of one analog station.

Comcast would not disclose which channels are seeing the new compression technologies, although it said it was constantly working to make sure it was "invisible" to its customers.

Last June, Comcast revealed its goal would be to offer more than 800 digital HD channels by the end of 2008. Analysts at that time were wondering how Comcast would be able to achieve a sudden doubling of its programming slate, speculating that it would provide perhaps only a few shows from some services but count them as complete channels.

The HD enthusiasts' cause was taken up this morning by Consumers Union, the publisher of Consumer Reports, which has already been nagging Comcast over its practice of throttling P2P users' bandwidth.