Interesting. Of course, the whole idea behind Variable Bit Rate encoding is that the human eye can't detect the lower resolution until the image is in motion, at which point the encoding kicks in to a higher bit rate. I've had Comcast HD for 3 years, and at first there were occasionally some problems with high-motion "artifacts", but I've got to say that over the past 18 months, the HD picture quality has been consistently impressive.

Your point seems accurate but academic. Like the difference between the actual definition of "broadband" and what telcos provide, for all practical purposes "High Definition" is what is given to us, not the real definition. Maybe grounds for a truth in advertising suit though.

Actually I have been noticing HD broadcasts quality reducing. It amazed me watching national sports broadcast game versus the local HD sports even that was on (both recorded in 1080i) and see so many more artifact on the local feed.

I thought it was just me, but knowing bandwidth limitations and competition it does not surprise me that more and more aggressive compression has and will take place.

In the end, you may just have to move to the best bandwidth service available at the time.

I always laugh at Comcast when they say they have more HD programming, but of course less channels than say DirectTV. It's a twisted game, that consumers will figure out in the end.

-Alan

alan sorry its the other way around. comcast for the most part DOES NOT compress local HD feeds. however some local HD stations reduce HD channel bandwith by adding local weather or news channels.comcast do however try to squeeze 3 HD channels into 1 QAM reducing bandwith by 50%. traditionally its 2 HD channels into 1 QAM. this of course is in response to satellite and phone company taking away their customers by theboat load.

I was wondering why I thought the HD images were starting to look a bit choppy... Thanks! I'll be calling Verizon the moment FIOS is available.

Comcast PQ has gone downhill. I was an early adopter in 2004, back when there were just 5 channels. The picture quality was _astounding_.

Now, it's garbage - take a look at the white yardage lines in a football game, or the outline of a player - you'll see the tell-tale tiling of cranked-up MPEG compression.

Thank god the word is finally getting out there. Personally, I can't wait to switch to Verizon (ugh, did I just say that?)

One QAM channel holds approximately 25% more data than one ATSC channel. This is why the cable companies lobbied so hard to prevent ATSC from being required on their systems.

The comparison doesn't take in to account the smaller ATSC data bandwidth as compared to QAM. With slightly more compression in the transcoding step the cable company can easily fit two full-HD ATSC channels into one QAM channel with no real noticeable degradation.

What Comcast is doing is transcoding to an even higher level of compression as well as increasing the block size (no doubt using a trade-secret process from Imagine Communications).

Hmm, do I dare suggest the FCC start regulating bandwidth per channel?? That's something that truly affects the viewing public instead of all the corporate politics Mr. Martin seems more interested in!!

Not all compression is equal, and not all HD channels require the same amount of compression to maintain PQ. I would hope Comcast keeps Sports and Action channels at 2:1, and put things like Hallmark HD, etc. in 3:1 QAM's. They are trying to squeeze in as much HD as they can, and want to do so on the cheap.Some of their HD PQ is therefore in decline. SDV is the way to go, as other MSO's have already learned.
BTW- let's keep the FCC as far away as possible! And if Verizon's PQ is better, than Comcast will adapt to keep the customer base.

We've all missed the real story here. I was looking at the print version of the story and noticed that the bitrates for Verizon and Comcast were remarkably similar (on a chart), although slightly higher for Verizon. That means Verizon is using the same compression techniques and is lying when it says it doesn't compress beyond what is received in the original signal (19Mbps).

And why the hell when I order NHL Center Ice package from Comcast, and Madison Square Garden broadcasts are in HD, the games are all shown in standard def? (channels 461-470 in San Francisco). What a scam!

I copied the mpegs onto my Playstation 3 and played them on my 42" TV and the difference is quite noticable.

"We've all missed the real story here.... That means Verizon is using the same compression techniques and is lying when it says it doesn't compress beyond what is received in the original signal (19Mbps)."

Not so. I'm not claiming what Verizon is doing or not, but the article just says 19Mbps is recommended for good quality. ATSC for instance is 19.38mbps *maximum*. This is a raw data rate of the MPEG-TS (MPEG transport stream). If the main video isn't using 19.38mbps, the remainder could go to other channels (weather etc), or even just be filled with null packets... it wouldn't make sense for cable or FiOS to transmit these nulls and mixed streams down the line.

I think the underlying principle in all this is has cable in general, as a technology, seemingly reached the limit of transmitting quality HD programming. I dont really know the capacity of satellite systems, if they compress or not, and how much room for HD growth they have, but I think its safe to say cable has no room for HD growth. It seems less an issue of Comcast vs Verizon, as both will use whatever they feel they can get away with to keep up in the HD TV world, and more an issue of cable being at the end of its usefulness. I dont know what the future will hold, perhaps Fiberoptic systems (to the home) are where landline communication needs to go. For the meantime if I was comcast, verizon, or whoever I would do exactly what they are doing. Keep trying to inject HD programming onto their networks for as long as possible, until a higher performance and more affordable landline tecnology can be implemented. If i didn't think Directv was the most brittle technology on the planet, constant outages from weather, I would say at this point Satellite TV seems to have a technological advantage in supplying growing HD programming, its just not limited by comprehensive networks buried in the ground across the country.

Meh,I don't really care.As long as I get the channels that I want,it doesen't matter.

Comcast doesn't hire idiots. Wait...i take that back. People in our customer service are idiots. But we, including me...unfortunately...work the best equipment we're given with. Pictures like the above can be a number of things, but its most likely a line issue. Once analog is done though...I swear things will be better. We test on a daily basis...though I'm not supposed to say that. Motorola is mostly the issue...if we had S.A. in all markets...things would be better. Don't believe me? Go out of town to an S.A. market and look at the difference...

Of course...most of the Comcast haters have never seen the inside of a headend...I forgot. So before you talk s-...know what you are talking about before you speak. I've seen most of you haters try to spit technical crap like you know what you're talking about. Try again...and do me and a few a favor the next time you try to write. Re-adjust the settings on that high def T.V. mom just bought you as you live in her basement. You're 30 or 40 years old. You spit out terms copied from the internet. Come up with something better. If you don't like the s- go to Satellite...you're still paying Comcast! Though you wouldn't know it...cause you're too busy masturbating waiting for you're mom to open up the basement door and call down..."

Engineer:
I have to agree, I live in an S.A. area and I have an excellent picture with my HD-DVR. And I've often heard poor results from the Motorola Crowds. I can only hope that my area, which was Time Warner at one point in time, keeps up the game as a S.A. area.
I also think you're absolutely right, with the SDV platforms coming into play, my market is going to launch an additional 50+ channels in HD. Which I'm sure will be compressed, but it won't be necessary to compress into the 3:1 format. Of course, you're going to have some HD junkie who has nothing better to do than complain about what he's getting. But that's the nature of the business. See the article entitled "