New big screen TVs: are compression artifacts normally visible?

Have only just breezed through the thread as I haven’t much time but, could the problem be the difference in the error correction capability in the various monitors (yours, your neighbor’s, etc.)?

Also, as a quick but pretty worthless note: broadcast signals are always your best bet. Of course, this only helps when the show you’re want to watch is on a broadcast channel, but whenever possible (e.g. the Super Bowl), use an antenna and switch over to broadcast. They don’t compress their signal anywhere near the amount that cable and satellite do.

My old monitor has no error correction at all; it’s strictly analog. The cable box handles that, although I can bypass it for analog channels. Certainly what’s inside the cable box can affect the output signal, but I’m not sure what that tells us. There are no user-programmable options or switches on either of the boxes.

Interesting. I still have an antenna in a tall tree, but would have to get a converter to use that signal. And we are in a fringe area, so the signal isn’t super quality.

Anyway…here’s the results of this morning’s visit by the local Charter supervisor. He was able to see the compression artifacts when I pointed them out to him and agreed that on some channels, at some times, they seriously degraded the image. The HD channels had the least degradation.

He said he sees the same thing on his TV at home. He did not know any more than we already did, and had no solution. He went thru all the cable box settings and said they were fine.

Apparently the cable box stores info over time much like the black box in an airplane, and he said he would access it and see if it had anything useful. He will also check every possible parameter in this neighborhood, hub and node for irregularities and get back to us. I don’t feel very hopeful that anything will turn up, but it’s good that all of this will be covered.

One thing that came up was the refresh rate of the TV. This model is 60hz, and the supervisor thought that a video connoisseur would probably be better off with 120, but felt that higher rates than that were overkill. However, he was unable to tell us if the refresh rate – which I imagine would be a factor for sports – was a factor in the compression artifacts we see. Anyone know about this?

So we haven’t reached the final answer to this question yet.

Incidentally, the supervisor said that I could take my converter box across the street and plug it in to the cable and it would work. The functions (which channels were enabled, etc.) would be according to my account, not the address at which it was physically located. Obviously you wouldn’t want to do this permanently because Charter’s techs would be confused, but it could be done for a test.

This may not be a factor, but we just found out that the Samsung TV that my neighbor bought was advertised on the Best Buy web site and touted by the salesman as having a 120hz refresh rate. But the Samsung manual and on-screen display says only 60.

My neighbor is contacting Best Buy to see what can be done, either exchanging the TV or getting a rebate, because he certainly didn’t get what he expected and paid for.

The outcome was we learned not to sit within 5’ of the TV. :wink: At 15’ the artifacts are much less noticable.
We’re not exactly fussy about the quality of our TV viewing. The bigger TV is because that our sofa is almost 15’ from the TV and, much like my friends who are discovering that their arms are no longer long enough to allow them to read a newspaper, that 25" TV was starting to get awefully small, even with my glasses on.

After all, John Wayne is SUPPOSED to look craggy, isn’t he?

Here’s some video info including stuff about refresh rates:

My interpretation of that is that refresh rate has little or nothing to do with compression and compression artifacts.

I have some friends with a new Samsung TV and I would suggest checking checking the picture settings. These are set for each input, so you have to check for the HDMI input for your cable box.

I would check the Digital Noise Filter and MPEG Noise Filter settings.

My friends were complaining that the picture was too sharp and that films looked like documentaries. This doesn’t make much sense, but the movies didn’t look right. I found turning off Auto Motion Plus fixed it. It was trying to convert low frame rate video to 120hz by interpolating.

I do tech for Kansas City’s best sports bar - the owner is consistently open to doing whatever is necessary to produce a better picture from more sources.

I’ve been able to test with the same signal from multiple distribution paths. I had a network feed of a live game in HD from:

Time-Warner cable
Over-The-Air
DirecTV
Ku DVB from a 10’ dish

The DVB dish utterly crushed the runner-up. It was 30 Mb/sec. The OTA was 19 Mb/sec. DirecTV was much, much softer and had more artifacts, but I wasn’t able to get a bitrate. And Time-Warner came at a distant fourth.

DirecTV has added more satellite transponders and has tried to maintain a consistent level of quality, though some channels are obviously worse than others. But the cable business is one that strives for a level of mediocrity just below the point where the peasants come after them with pitchforks.

It’s NOT your cables or splitters. The inadequate bitrate might be disguised by a more recent cable box that will mask the artifacts by softening the picture. Some TVs, like Sony, have their own processing that reads the MPEG stream and replaces some edge blocks with their own library of blocks. To me this looks simultaneously soft and artificially sharpened, but some people like the look.

Thanks, Gaffa, that’s valuable information.

It seems a shame that cable comes in last – from a raw technology standpoint, cable is the one medium that has the greatest capacity (fiber blows any wireless/satellite away, at least from a theoretical standpoint).

I don’t know the bitrates in this case, and your figures are probably referring to HD. But bitrates and compression schemes are not the same thing – one can be high, the other low, and vice-versa. Too low in each case results in different distortions, and I think we are seeing compression distortions, not bitrate ones. Still, there could be some connection.

Just for a comparision – and keep in mind this is standard def, 720x480 resolution – I process our public access TV signal at from 5000Kb/sec to 8000, depending on the material. Talking heads (like government meetings, interviews) get the low, sports the highest, average content gets an average of 6M-7M. Those numbers have proved to be just about right for a typical analog TV viewer around here. At those rates, I am able to detect no (or very few) artifacts in the outgoing signal (the signal we send to Charter for distribution).

(The max I can broadcast is limited by our video server, and 15Mb/sec is tops there.)

JoelUpchurch, I will check those settings the next chance I get, but I doubt if they will affect compression already imposed upon the incoming signal except perhaps to cover artifacts up.

well, the thing is, cable wasn’t required to switch over to digital like broadcast was, so depending on the provider there can still be plenty of analog channels hogging that capacity.

Cable wasn’t required to be digital, but it already was before broadcast was, at least partly. Charter had projected to be ALL digital by 2012 in my area, but now I understand that is being pushed back indefinitely, maybe because of customer backlash. Lots of Lil Ol Ladies with Dumonts who don’t want to convert.

I don’t think that is quite fair. It might be folks like me who have devices to handle analog cable channels that are far more capable than the ones the cable company wants to foist off on me. Time Warner, Everest or DirecTV will never give me a box that will allow me to automagically skip every commercial like my beloved ReplayTV. I would consider watching commercials a dramatic step backwards.

Now if they would give me a box that could take a digital signal in and output 99 analog channels so my ReplayTV could tune them in, I’d be a happy camper. Until then, they can take their wretched Cisco boxes that take 10 minutes to boot up and shove them up their collective asses.

The thing is, it is only theoretical at this point. If they could deliver fiber to my home, it might. But at this point, it is fiber to my neighborhood, at best.

When I mentioned in an earlier post that–because of using less compression on the head-end–OTA will have a better signal than cable or satellite, I was thinking of DirecTV and the like when I wrote satellite. I wasn’t considering Ku band. Semi-mea culpa… I didn’t realize that Ku was a viable option for anyone other than a broadcaster or satellite truck service.

Naturally, OTA will only have a better signal (vs. cable, DirecTV) if you are able to snatch a strong signal out of the air. If you live in a fringe area and/or don’t have an appropriate antenna, I think you’ll be happier with a cable or DirecTV transmission. The channels will still be a lot more squashed up (= less picture data) than OTA, but at least you’ll be able to consistently tune it in.

As for DirecTV adding more transponders and the mediocrity of cable:

More transponders is good for the “last mile”, but DirecTV and similar sat services, (along with cable), will out of necessity always need to compress their signal much more than OTA. You simply have to to fit a bazillion channels into one signal.

And yes. By and large, cable is a bunch of mustache twirling, 1890’s-style monopolists who will only give you the very least they can get by with. And your “peasants with pitchforks” imagery is closer to reality then you might think. Local governments have shown very little interest in regulating the cable industry (as municipal utilities), not to mention the hands-off approach of the Feds and most states. Pitchforks 'n Peasants is about the only thing that could give that behemoth pause.

Fuck’em all. Pretty much all media will be delivered via internet soon enough anyway. That’s why it is key that ISPs like Comcast, AT&T, Time-Warner, etc., not be allowed to use their monopolies for proprietary media delivery and/or throttle the internet delivery of competing media providers. Really, an ISP shouldn’t be allowed to be affiliated with media providers, producers, networks, studios, entertainment corporations, etc., in the first place.

I’m talking about Net Neutrality which is a much, much, much, much* bigger deal than even most intelligent and involved people (like Dopers) think.

*I used a ridiculous number of "much"s on purpose because it is that important an issue, and it gets very little attention.

EDITED TO ADD: This concludes today’s total hijack. Carry on.

Broadcasters, satellite trucks and very dedicated sports bars with access to technical people who know how to hook this stuff up and find the signals. I find it hard to believe that people think a 10’ dish is some kind of white elephant. Put a pair of wide-band splitters and a DiSEqC on that sucker, hook up a DVB receiver with blind search and you’re rolling! Of course you’ll need a TV with PIP to tune it as there are no consumer priced DVB receivers that can control a linear actuator.

I’m not sure what aspect you are saying is not fair. Is it the coming forced all-digital network? I have mixed feelings about that, but it may be a subject for another thread.

I can agree with you about the cable/converter box situation. Charter rents them for $5 per month. You cannot buy them from Charter or anyone else, and you absolutely need one if you want to access ALL the features you are paying for. And you need one for each TV in the house unless you can accept watching the same station on all of them all the time.

A new digital TV can access SOME of the channels, but not all, and NONE of the features, and many of the channel assignments are wonky.[sup]*[/sup] I understand there are some TVs with “personality cards” that can be taylored to Charter’s codes, but I haven’t seen them anywhere in my neighborhood or TV stores yet.

  • Charter changes channel frequencies without warning or logic – not telling the customers or the cable technicians, even the supervisors. If you have a converter box, the translation from frequency to channel number is handled invisibly, but if you have a digital TV, you may wake up one morning to find that channel 97 is now channel 9.9, and unless you know enough to dig into a menu to re-scan the available channels, it will disappear from your system.

Only a conspiracy theorist would claim this is deliberate, but when the channels that disappear are the ones they don’t make any money from and don’t promote, and this happens twice in 3 years, one has to wonder.