Test Shows Comcast’s HD Squeeze In Virginia
A/V Enthusiast Finds Comcast HD Bit Rates As Much As 28% Lower Than Verizon’s
By Todd Spangler -- Multichannel News, 3/27/2008 11:12:00 AM
Comcast has said it can pack three high-definition signals into space typically used for two—without viewers noticing a drop in quality. But at least one viewer has.
A member of AVS Forum, a community site for audio/video enthusiasts, has posted the results of his comparison of the compression rates for 10 HD channels offered by Comcast and Verizon Communications’ FiOS TV in Northern Virginia.
The user, “bfdtv,” said his test showed Comcast is delivering certain MPEG-2 HD channels at bit rates as much as 28% lower than Verizon, resulting in lower-quality pictures.
For example, an A&E HD broadcast of an episode of The Sopranos had an average bit rate of 18.66 Megabits per second on FiOS TV, whereas Comcast’s version was 22.4% lower—at 14.48 Mbps. Verizon, like most cable companies, distributes linear TV programming in MPEG-2 format.
Multichannel News contacted “bfdtv,” whose real name is Ken Fowler, an audio/video buff who lives in Arlington, Va.
Fowler, reached by phone Wednesday, said he works in the financial services industry and has no stake in the success of Verizon or any other pay-TV provider.
Fowler said he conducted the test -- and posted screen captures showing the different picture quality between the two services -- to confirm his suspicion that some of Comcast’s HD channels were being more highly compressed than Verizon’s. “I did notice the difference, and I wanted to know that I wasn’t seeing things,” he said.
Comcast senior director of corporate communications Jenni Moyer said the company could not comment on Fowler’s test or his methodology.
“HD picture quality is extremely important to our customers and to us, and when we conduct picture quality tests, we use independent third-parties and industry-accepted testing methodologies with expert and consumer participants,” she said.
Comcast, along with the rest of the cable industry, is facing an HD balancing act.
Cable providers need to add high-definition programming, to fight the 90-plus HD lineup now offered by DirecTV. But they also need to ensure they don’t sacrifice quality for quantity—and risk disappointing the likes of AVS Forum’s habitués.
In his testing, Fowler recorded the same programs as delivered by FiOS TV and Comcast, using two TiVos with CableCards.
He then extracted the video files from the TiVo digital video recorders and calculated average bit rates for each program by dividing the length of the video in seconds (as displayed by MPEG-2 video software VideoReDo) with the overall file size.
Fowler found Comcast has not applied higher compression rates to every HD channel. High-definition signals from local broadcast stations aren’t recompressed, he said, and as of March 18, ESPN HD, ESPN2 HD and Comcast SportsNet also remained “at full quality.”
But on Comcast’s more highly compressed HD channels, Fowler said, the video exhibits noticeable blurring during high-motion sequences.
Fowler conceded that his standards for whether one provider’s HD looks better than another’s may be higher than the typical subscriber.
“I’m probably not the average viewer,” he said. “The average viewer probably isn’t going to go on AVS [Forum] to find out information like this.”
Now, why does he subscribe to both FiOS TV and Comcast in the first place?
Fowler said he switched from Comcast to Verizon FiOS last year because it offered faster Internet access and more HD channels for less money.
About a month ago, Comcast in Northern Virginia launched several new channels that FiOS did not yet offer, including CNN HD, Sci Fi Channel HD and USA Network HD. In addition, Comcast announced it would carry high-definition telecasts from Mid-Atlantic Sports Network, which is “important to me as a Washington Nationals fan,” Fowler said.
After discovering FiOS would not have those new HD channels in his area before late July, he decided to switch.
Comcast also offered him a special deal—digital TV service with HBO and Starz at $39.99 per month for six months—which “certainly played a part in that decision,” said Fowler.
And because his FiOS TV service contract wasn’t up yet, he decided to do a head-to-head comparison.
“I’ve been around AVS [Forum] for a long time,” Fowler said, “and I’m one of the advocates for getting the best possible quality you can.”
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Surely 'Mr. Fowler' not just 'Fowler' ?
*Mr* Lord - 3/31/2008 12:53:00 PM EDT -
Assuming that Comcast IS indeed putting the "Squeeze" on HDTV PQ and thus on customers.......then please allow me to offer this observation: I suspect there will most likely be a class action suit lurking in the woods. Let their "professional" mouthpieces rebut this. It seems to me that what the customers will get is a camel (a horse designed by a committe)in so far as a "corporate response". Comcast should know that even though they are a megalopoly..we the CUSTOMERS are not dumb and we will not, Howard Beal from "Network" yelled: Were "mad as hell and won't take it anymore!"
Ken Milan - 3/28/2008 2:14:00 PM EDT -
Statistics can prove anything you want. However when you look at the pictures and movies you can clearly see poor HD quality.
- 3/28/2008 2:45:11 AM EDT -
Ken - no, the point is the Comcast picture *DOES* look worse at the lower bitrates.
Check out AVSForum.com link to see the side by side comparisons and judge for yourself.
avs_guy - 3/27/2008 8:14:00 PM EDT -
Well, of course Verizon's bitrates are going to be higher. That's because they use Constant Bit Rate (CBR) encoding. Comcast is using new Variable Bit Rate (VBR) encoding, so the bit rate is going to fluctuate up and down with the level of action. The Sopranos is not a high-motion program, so of course its VBR will be lower. If you have 3 HD channels in a QAM, in theory there would be occasions when bitrates for the 3 channels peak at exactly the same time, but this would not be typical. From what I've read, there's no subjective or objective data to show that VBR is less sharp.
Ken - 3/27/2008 5:15:00 PM EDT
Squash Match
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03/29/2008
