A really interesting article was posted to MSNBC.com today (http://www.msnbc.msn.com/id/24238071/) regarding the methods that cable providers like Comcast and Time Warner take to squeeze all those HD channel down their pipes. It so happens that many of the HD channels undergo some form of compression before they are picked up by your nice HD television set.
In an excerpt from the MSNBC.com article……
Ken Fowler of Arlington, Va., compared Comcast signals with those on Verizon Communications Inc.’s all-fiber-optic network, which doesn’t have the same capacity limitations. Fowler found the higher-compressed HD stations, including Sci Fi, Animal Planet, the Discovery Channel, the Food Network and A&E, fared particularly poorly.
He analyzed the signals by recording them on a digital recorder, then transferring them to a personal computer for analysis. He found there was much less data, measured in bit rates, flowing to some channels than others.
For example, Discovery’s bit rate was 14.16 megabits per second on Verizon’s FiOS system but only 10.43 Mbps on Comcast; A&E HD was 18.66 Mbps on FiOS compared with 14.48 Mbps on Comcast. The FiOS system didn’t offer Sci Fi HD, which Fowler’s testing showed at 12.59 Mbps on Comcast.
He found the signals from the major networks and ESPN weren’t getting the increased compression.
In an interview, Fowler said he reran his analysis about two weeks ago and found “basically the same thing.”
Philadelphia-based Comcast wouldn’t identify specific signals that are 3-to-1 compressed, and a Sci Fi channel spokeswoman referred questions back to Comcast.
Harrar said the company works to make sure any new compression technology is invisible to consumers, but Comcast is “constantly monitoring our network and making adjustments” for best picture quality. The company has been rolling out the new compression technology at different times around the country.
Time Warner probably uses compression on their network too, although they claim to rely on “golden eye” engineers that do A / B comparisons on signals before new technologies are put into place. So what does this all mean? All this goes to show that the cable providers have a lot of catching up to do with the services like FIOS where bandwidth constraints don’t hinder the ability to provide uncompressed feeds. On the other hand, if compression sucked so bad, the evolution of the Apple Ipod and MP3s wouldn’t be so popular. It’s when compression techniques go to the extreme, and the end result of an audio or video signal becomes injected with artifacts that were never present in the original content. If I had a choice of picking a compressed or uncompressed signal I would definitely go for the latter. Maybe the providers will come out with a cheaper HD service called ‘Sorta HDTV’.
