I looked at a bunch of HDTVs at Best Buy recently. The picture quality was uniformily terrible. In particular, whenever something onscreen moved rapidly (like an explosion or an athlete) the image seemd to break up into fairly large blocks. I assume that this is due to the signal being split to multiple TVs and it would not look like this at home. Is this correct?
Yes. Splitting the signal to loads of TVs through long cables will introduce artefacts (blocking) into the image that you shouldn’t get at home, although if your digital signal from whatever source you use suffers from interference then you might get it too. You can also get some artefacts from high speed motion if the TV is improperly set up (which the TVs in the shop are likely to be, as they’re usually left on the factory default settings).
Yes. The effect you describe is called “macro blocking”. I see it on rare occasions on one or two my cable channels. Never happens on a live broadcast. I have Comcast digital cable and TiVo, and I think in the year I’ve had it I’ve seen it maybe five times, intermittently.
IMHO, try going to a sports bar or the like that is broadcasting a football game in HD. I think you’ll notice the difference.
Eh, this is strange. The general advice here is to not expect the picture to look as good as in the store when you come home with your new TV set. Since at the store they run full HD stuff, and most content at home is normal low definition and looks terrible.
The picture quality on most HDTV’s is excellent, most people wow about how sharp they are. The problem is that most people don’t have such high resolution streams at home. With high definition content (blu-ray etc) it will look excellent, while a regular old school TV channel will look crap (as usual).
To OP: you should find out what signal you have at home, whether you have any high definition channels, and so on. They should look good. There’s no escaping that low definition channels will look bad, but that’s life. In that sense, the TV’s are generally ahead of the game, with TV broadcasts trailing behind in quality.
Either your store does something stupid to get such bad quality, or they are running a plain low-def TV channel.
Digital signals shouldn’t be split. And the store isn’t likely to have 50 separate feeds. It’s the splitting that’s making it shitty. As Szlater pointed out.
In the stores here they have perfect image on all 50. They must be doing something wrong where you live then.
A lot of stores set up HD sets really, really poorly. Any big box store in particular, such as Target or Wal Mart or Shopko. It’s embarrassingly rare to see an HDTV properly set up in such places, and there is the aforementioned problem with splitting the signal too much and using cheap, overly long cables and a crappy source to begin with. Best Buys are a tossup in terms of doing a good job setting up their demo sets. Most of the time, they don’t know what the fuck they’re doing.
Compared to such crappier installations, chances are yours will look a lot better when you set it up at home, because you will probably:
- Take the time to set it up properly.
- Not try to set up more than one display to play from the same, split source.
- Have a better signal to begin with, and better cables as well.
More expensive cables make very little to no difference with digital signals. I saw a test between a wire coat hanger and a £500 1m cable (for digital audio interconnect) and there was no discernable difference. The only thing to look for is adequate shielding for long runs, but there’s absolutely no point in spending lots of money on expensive cables.
I guess it’s different where I live then. Here the stores set them up perfectly to show off the capabilities, while people at home are less good at this.
Again, I guess good HDTV broadcasts are more widely spread among consumers where you live. Here the stores use the best stuff, but people get disappointed when they come home to their regular signals (similar to tv-ads with false advertising, since with most broadcasts it won’t look as good as they show).
Does anybody know how this splitting is done in stores over there? A digital signal should be easily duplicated with no loss of quality.
Where are ya, Henricheck? Here in Cali, USA, most video stores I’ve seen have craptacular HD displays – especially Best Buy. I’ve seen quite a number of actual HDTVs in homes and the store ones always look worse. I always wondered why they never bothered fixing that; I guess they figured the average consumer probably wouldn’t notice (I have to agree, having also seen a lot of HDTV owners watching stretched SD with the aspect ratio all wrong and bragging about how awesome it looks…)
Why does splitting matter? It’s a digital signal.
Because although all the 1s and 0s remain in the same order, they become smaller each time the signal is split. . Eventually, the signal (or parts of it) gets lost in the background noise.
Hogwash. There’s nothing wrong with splitting a digital signal. You should use a good quality splitter that’s rated for 1GHz signals and introduces as little signal loss as possible, but there is absolutely no rule that you should not split a digital signal. With the proper amplification, you can split a plain household digital signal 32 ways and still have it look perfect.
However, that’s not to say the guys down at Best Buy have proper amplification and/or know what they’re doing. There are plenty of ways for people who don’t know what they’re doing to screw up large multi-TV displays. One way I’ve seen it done is to send a digital signal into a tuner box which outputs component video, and that signal gets split out to 10 TVs. The results aren’t good.
The bottom line is you can’t evaluate picture quality in any meaningful way on those massive displays unless you can personally verify how the connections are made. You definitely can’t trust much the salespeople say about it. About all the information you can truly get from such a display is “this TV can produce a picture at least this good.” I’d try to get one of the salespeople to hook a blu-ray player directly to the TV you’re considering in order to evaluate it. Of course, if you ask for this at Best Buy, they’ll act like you’re a nut, which is one reason not to buy a TV there.
The main reason HD signals in big electronics stores look like crap is that the source is crap. They use one of two mediocre sources:
[ul]
[li]An HD simulator from a company like Sencore that has HD MPEG video on a hard disk.[/li][li]A dedicated HD satellite channel.[/li][/ul]
In the first case, the simulator has limited hard disk space and new material has to fit on DVDs. So the bitrate is usually lower than broadcast.
In the second, they are not paying for a full satellite transponder. Instead, they’ll try to get away with the smallest amount of bandwidth.
Bad cables do not show up as macroblocking. That is the exclusive province of poor encoding or a decent encoder starved of bandwidth. Most independent stores will distribute component signals through component distribution amps. A giant store like Best Buy will distribute via RF from one or more HD simulators.
This is somewhat less true than it was 3-4 years ago, but I often used to see HDTVs hooked up to the exact same SDTV inputs as the rest of the TVs being sold on the floor – in fact, all they’d done was to swap in the new HDTVs to where they used to have standard TVs plugged in for display – but now “stretched out” to 16:9. They were taking a highly split low-res analog signal (RF or composite video), putting it on a large screen so that the poor quality of the image was even more apparent, and then distorting the image on top of that.
Bleh!
I watch HD trailers a lot, downloaded from Apple and viewed on my Sony Vaio laptop. They have 3 options, 480p, 720p, 1080p, and I generally use the 1080.
Is this better or worse quality than I could expect from HDTV?
If you get a 1080p capable TV and feed it with a 1080p source you’ll get similar quality.
I believe that HDTV over digital satellite and cable (and soon freeview) in the UK broadcast 720p because of bandwidth constraints (the operators want more channels not higher quality), so HD broadcasts won’t be quite as high quality as say the picture from a Blu-Ray Disc or a download from Apple. They will however be considerably better than non-HD broadcasts and standard definition DVD.
I don’t think the phenomenon the OP is observing has anything to do with HD per se; it’s to do with digital broadcasting versus analogue. I’m not sure how it works in the US - do non-HD channels also broadcast digitally, or does digital = HD?
I don’t have HD but I do have digital (cable) TV. And yes, fast-moving pictures are somwtimes prone to breaking up into a mosaic pattern. The problem is that broadcasters try to cram too many channels into too little bandwidth. The main big-ticket channels are usually OK, but minor channels such as Eurosport 2 seem to get allocated whatever bandwidth is left over once everyone else has had theirs.
Unlike analogue, digital is “all or nothing” - you either get a good picture or it screws up entirely. A signal strength that would give an acceptable, but slightly snowy picture on analogue often gives a blank screen or a mass of squares on digital.
It doesn’t happen very often, but often enough to be annoying.
Sounds to me like the problem is coming from video compression techniques, and that is still going to be a problem at home unless the cable company is using some superior video compression technique. Over-the-air signals are significantly less compressed and tend to look better, but generally, most TV scenes involving a lot of moving activity are going to result int he blocky look.
So, in general, it is impossible to know beforehand what a given TV will look like in my home because:
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The video source used in the store could be any one of a variety of types, some of which result in a sub-standard picture or it may be distrbuted to the TVs incorrectly.
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The cable company may choose to compress the signal in such a way that it creates a substandard picture.
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I may connect the TV incorrectly.
Are there any reputable online reviews of TVs and/or explanations of which cable companies use what compression?