djc
04-21-2008, 11:44 AM
Owners of pricey home-entertainment systems complain quality isn't there
Limited capacity
The problem is viewers want more HD channels at a time when many cable and satellite providers are at the limits of their capacity, said Jim Willcox, a technology editor for Consumer Reports magazine.
"They have to figure out a way to deliver more HD content through their distribution networks," he said.
Compressing the signal is cheaper than costly infrastructure upgrades to increase capacity. Satellite TV providers — including DirecTV Group Inc. and Dish Network Corp. — also have the option of launching satellites to boost the number of HD channels on their systems.
While information is nearly always lost when signals are compressed and then uncompressed, the process can theoretically be made unnoticeable to eyes and ears — and Comcast says it should be.
But some viewers say they can see it. Willcox said complaints about compression have been showing up on Web forums, including the AV Science Forum, a site for serious audio visual enthusiasts.
In a posting on the AV Science Forum, 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.
Limited capacity
The problem is viewers want more HD channels at a time when many cable and satellite providers are at the limits of their capacity, said Jim Willcox, a technology editor for Consumer Reports magazine.
"They have to figure out a way to deliver more HD content through their distribution networks," he said.
Compressing the signal is cheaper than costly infrastructure upgrades to increase capacity. Satellite TV providers — including DirecTV Group Inc. and Dish Network Corp. — also have the option of launching satellites to boost the number of HD channels on their systems.
While information is nearly always lost when signals are compressed and then uncompressed, the process can theoretically be made unnoticeable to eyes and ears — and Comcast says it should be.
But some viewers say they can see it. Willcox said complaints about compression have been showing up on Web forums, including the AV Science Forum, a site for serious audio visual enthusiasts.
In a posting on the AV Science Forum, 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.