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What causes the slighly jerky motion I always see in store HDTV displays?


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#1 of 27 OFFLINE   Brian W.

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Posted May 27 2007 - 05:14 PM

I still haven't taken the HDTV dip, but I've come really close several times. I'm sure I'll buy one by year's end. But why does every HD display I've ever seen -- whether at Best Buy, Circuit City, Costco, wherever -- display a slighly jerky motion when objects move from side to side? Also, a sort of pixelization or graininess seems to appear when objects move quickly. I see this on $5000 models as well as $700 models. I see it with BluRay and HDTV. I check the back of the sets, and they do appear to be hooked up via the HD inputs. They just never seem to have the natural, smooth movement of analog TV. What causes this?

#2 of 27 OFFLINE   alphanguy

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Posted May 27 2007 - 06:40 PM

Brian W... this is the "dirty little secret" of the LCD and Plasma formats. If you could lay your hands on a store display of a CRT direct view HDTV, then all those problems you mentioned are non-existent. You'll get alot of argument from people who don't want to believe it happens, since they spent a ton of money on their sets, or they simply have no eye for detail and don't notice it.... but the direct view CRT is the only type of TV I will ever own, because it doesn't jitter or smear with very fast motion. Yes, it's heavy... yes it takes up space, but also some burglar isn't going to break into your home and walk out with your 2,000$ flat screen under one arm. The manufacturing companies are trying to phase out direct view CRT's for one reason, they make bigger profits on plasma models, and they can sell you expensive replacement bulbs for LCD's. The electronics manufacturers don't ever want things the way they USED to be... you purchase a TV and have it for 15 years without any trouble, they need to find some other way to bleed you dry, whether it be replacement bulbs, or planned obseletion. There are a certain amount of people who think plasma looks better because others TELL them it does, but good for you, you open your eyes and can see the truth. With all HDTV's I've seen, the sony direct view CRT models blows all away by a hundred miles. Now, you will see posters swarm on me like flies on a cowpie for saying all this, but I'm not blind, and once I point out the shortcomings of the LCD and plasma formats to people, most DO notice it once they LOOK for it. I will say, however... that DLP shows promise, it seems to have the least of that problem, give them some time, and DLP might be a viable alternative.

#3 of 27 OFFLINE   troy evans

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Posted May 27 2007 - 07:13 PM

Brian,I think in a way You've answered Your own question.Crts have lower resolution than HD displays hence You Don't see the fine details and motion can appear smoother.Now on HDTVs theres no getting around it,They must be calibrated! When You see a HDTV in the stores You're going to notice flaws because they have a tendency to max displays out so they don't look too dim under there bright floresent lighting.Also,when a store feeds a video signal to displays they typically use one source i.e. DVD player,HD cable channels,etc.to feed all monitors.I'm sure i don't have to tell You what happens to one signal split between 30 or so TVs.I owned a Panasonic Tau 36" crt and it was a fantastic television.I Now own a Samsung 42"plasma HDTV display.Make No Mistake,HDTV when You get one setup in Your Home WILL BLOW YOU AWAY!
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#4 of 27 OFFLINE   alphanguy

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Posted May 27 2007 - 07:20 PM

It's not the higher resolution that causes the problem, it's the shortcomings of the format, that's why you see that problem with High defenition plasmas, and NOT with High definition CRT's. You'll never find those issues in a movie theater, and you can't GET higher resolution than a projector and film. Just check out a Sony CRT direct view HDTV and all will be revealed to you.

#5 of 27 OFFLINE   troy evans

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Posted May 27 2007 - 08:16 PM

Well,from Brian's original post I don't remember Him saying what display types He was comparing only that He was thinking about making the leap to an HDTV display over a Crt but noticed jerkyness and pixelation in motion images on whatever HDTV displays He was watching.He could have easily been talking about a Crt display.But,I doubt that,simply because Crt displays on the sd level CAN NOT TOUCH the quality of a HD plasma.Even the best standard def Crt couldn't compete.Now Your Sony HDTV may very well be great.But,again He was talking about going from standard def to hi def if I'm not mistaken.I'm also not sure why You make the projector refrence since were not comparing those to anything at all here.Also,when I had My Crt even watching cable sometimes had pixels in the screen this is a problem from the source not the display itself.Hell,it could even result from a bad interconnect i.e HDMI,Component,etc.Again since this was missed the first time let Me state again,There's nothing wrong with Crt.I owned one for many a year.The fact is Standard Crt vs. Plasma=Plasma wins hands down!But Don't believe Me.Ask Anyone on these forums who have HDTV Plasmas if there having these problems.I'll bet most ARE NOT and they will tell You How impressive the Plasmas are.There's what I would recommend,ask all the Plasma owners.See what they tell You.
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#6 of 27 OFFLINE   Rex.G

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Posted May 27 2007 - 09:20 PM

My $0.02 Let's avoid the technology argument. They all have their place and can hold their respective grounds. I believe what Brian is describing is the disadvantage that comes with an interlaced signal. With 1080i, pixelation can be seen in fast moving action or with something like an on-screen explosion. It is my understanding that the 1080p signal eliminates this problem. I see this sort of thing all the time with my display. For example, when watching a basketball game obvious pixelation can be seen when the shot is following the action down the court. But if there is a close-up, like for free throws, the shot is crystal clear. I am not aware of any networks that currently broadcast in 1080p. My suggestion, to anyone in the market for a new TV, is to only consider displays that are capable of 1080p signals. There are MANY LCD’s and plasma's available for cheap prices, but most only provide 720p and/or 1080i. It's my opinion that these models are already outdated and should be avoided especially if one is concerned about having to upgrade in a couple of years. Invest in a 1080p display and HD DVD (format of your choice). There might be 1080p programming available from your television provider before the end of the life of a new display. Brian, you should look into the differences between interlaced and progressive (there is information available on this board). It will help you understand how the technology has evolved and how to make an educated choice when purchasing any kind of video equipment for use in a home theater type application. In short to answer your question: The reason you are seeing pixelation with HD displays is because you are not watching it in the 1080 progressive format. I hope this helps and does not confuse.

#7 of 27 OFFLINE   troy evans

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Posted May 28 2007 - 05:35 AM

Okay,Peter Your on to something there.Here's the point though,even with Your post You point out that a basketball game You're watching on cable or an explosion,although You didn't mention the source were pixelized.Dvds and HD broadcasts are pushing between 480p to 1080i,depending on the source,You're either going to have a good picture or a not so good picture.HDTVs don't decide how to relay information coming from a source.It's either there or it's not.If the source loses information as in an HDTV broadcast,even standard broadcasts lose information from time to time,We've all seen that or standard Dvds don't have the information content on there discs You're going to see pixels as a result.There's no getting around that fact.When I watch HD DVDs on My HD player hooked to My 720p/1080i plasma I don't see any remote sign of these jerky/pixel problems.Peter is right though about interlaced vs.progressive.Look at it this way,if You put a Ford focus car on a Nascar track of course it can run the track and make the laps.If You put a Nascar on the track it'll make the same only performance wise it'll blow the Ford away.the same can be said with source material.That is just the fact.
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#8 of 27 OFFLINE   Joseph DeMartino

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Posted May 28 2007 - 09:06 AM

The first and most obvious answer to the original question, which does not (unlike some of the replies) limit itself to specific types of HD set, is that sets in big box stores like BB and CC and always horrible maladjusted and look like crap. When I got my first HD set (a small LCD panel) and fed it an HD cable signal right out of the box, I nearly wept and thought I was going to have to return it the next day. 20 minutes with Video Essentials and I was thrilled with it. I immediately started saving up for a large microdisplay for my living room, (which also looked terrible right out of the box) and now I can barely stand to watch SD TV at other peoples houses.

90% of the graininess and blockiness you see in big box stores is explained by the out-of-box, "torch mode" video settings, designed to make everything look bright and colorful under in-store lighting on a wall with 50 other TV sets - you know, exactly the kind of viewing condititons you have at home. Posted Image

Another 5% is probably the inherent limits especially of LCD, although even here different brands (and different price levels) will get you different results.

The last 5% is source material. Over-compressed cable and satellite signals and glitches at the network end can cause a picture to break up, too. So can signal attenuation and latency. Even with DVD and hi-def DVD signals can be affected by electrical interference and by being run through too much cable.

I notice that alphaguy completely ignores DLP, LCoS and CRT rear-projection - probably they don't suffer from the problems he discusses, and therefore underimine his argument. Never listen to anyone who only gives you half the story on anything.

A couple of points from other posts above:

1) Nobody is going to be broadcasting in 1080p in the foreseeable future. To provide 1080p requires twice the bandwidth of 1080i and there is quite literally no demand for this. (Statistically speaking.) Why would a network give up the bandwidth for an entire extra hi-def channel or two, or several lower def subchannels, in order to provide a service that no one is asking for and that (given the installed base of sets, viewing distances, how little most of the public knows about how to adjust a set) practically no one will even notice.

2) This mostly doesn't matter, because except for the handful of direct-view CRTs out there and the dwindling number of CRT RPTVs, none of the current sets can display an interlaced image anyway. Every set that uses a fixed array of pixels to create an image is inherently progressive. Regardless of input signal, they all display their native resolution (720p, 768p for some LCDs or 1080p) all the time. That's all they can display. The accomplish this by scaling any non-native signal to their own display resolution.

Interlaced direct view CRTs, by the way, are being phased out as a category because people are gravitating to bigger sets for their main system and to hangable flat panels in smaller sizes, not because of some manufacturer conspiracy - if there was still huge demand for CRTS, Sony and everyone else would be making CRTs. But there isn't - in part because CRTs are physically bulky, heavy, run hotter and need more ventilation than the most popular sets (LCDs) in the same size range.

CRT RPTVs are being phased out because even the most compact of them are bulky and heavy compared to miscrodisplays, and they are subject to burn in. My old Toshiba 56" widescreen - SD - RPTV went through three moves with me - the last from a 2nd floor condo with no frieght elevator to a 3rd floor condo with no frieght evelvator. It had permanent burn-in from switching between 4:3 and widescreen material, and after 10 years the image was probably half as bright as when I bought it.

But it still had some life in it, so when I knew I was buying a new 56" HD set, I donated it to a local charity which sent a truck and two guys to collect it. The thing weighed over 300 lbs and it took all three of us to manhandle it down the stairs. It was like moving an upright piano. (Which I've also done.) My new set is under 100 lbs and a couple of feet shorter and was no problem for the delivery guys to carry up the stairs.

There is no manufactuer conspiracy. Instead there is a little thing called "consumer demand". On top of everything else, people are just plain starting to view CRTs as "old fashioned" and they aren't buying as many, despite the attractive prices, so the manufacturers are going where the dollars are - flatscreens.

BTW, the manufacturers don't make much money on the replacement bulbs for microdisplays, because they don't make the bulbs. They buy them from subcontractors, which means the public can also buy them elsewhere. I bought two spares for my LCoS set when they were on sale and have them on the shelf for when I eventually need them. JVC doesn't see a dime of what I spent. And when I do pop one of the bulbs I spent $125 on into the set I spent $1800 on, I'll effectively have a brand new TV. The image will be as clear and bright as the day I bought it. It will not have degraded as the phosphors that make up the image wear out, as with any CRT and plasma.

Brian:

You need to take a look at some properly-adjusted, or better-still, professionally calibrated, HD sets - of varying technologies - in order to make a rational decision about HD. If you have any high-end A/V places in your neck of the woods, take a walk around the show room. You may still end up buying at CC or BB, but you'll have a better idea of what the set you buy is really capable of.

Regards,

Joe

#9 of 27 OFFLINE   Brian W.

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Posted May 28 2007 - 06:10 PM

Thanks for the replies. Hmm... I'm in Los Angeles, so maybe I'll have to drive down to Ken Crane's one day and see what they've got set up. But I do give alphanguy's post some credence... I can't specifically recall seeing this problem on direct view HD sets.

#10 of 27 OFFLINE   troy evans

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Posted May 28 2007 - 06:16 PM

Joseph You're correct.You were more elaborate than I was and I agree.
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#11 of 27 OFFLINE   Joseph DeMartino

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Posted May 28 2007 - 11:52 PM

1) Plasma and LCD are "direct view" sets. You are looking right at the thing that creates the image. Only projection systems (rear or front) aren't "direct view". 2) There are damned few CRT-based direct view TVs left on the market. Most of the CRTs you'll see in stores now are digital, but not HD. (Most are Enhanced Definintion, capable of displaying 480p and a few are still SD, limited to 480i.) So I can't imagine that you've seen very many of them. 3) You haven't indicated if you've only seen these problems on LCD and plasma or if you've also seen them on microdisplay systems. (DLP, LCoS, LCD-RP) Regards, Joe

#12 of 27 OFFLINE   Gregg Loewen

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Posted May 29 2007 - 01:21 AM

slight jerky motion? This could be from the conversion from film to video (24 frames a second to 30 frames a second). This is becoming a big issue as all these technologies mature. When film is converted to video there are frames added which can cause a "judder" effect. The old school solution is better processing, the new school solution is better processing AND the ability of a display to show 24 FPS, or a multiple of 24 FPS. (48, 96).

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#13 of 27 OFFLINE   Brian W.

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Posted May 29 2007 - 03:25 PM

I don't even know what a microdisplay system is, Joe.

#14 of 27 OFFLINE   Joseph DeMartino

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Posted May 30 2007 - 02:58 AM


I named them in the parentheses. Posted Image DLP (Digital Light Processing), LCoS (Liquid Crystal on Silicon. Marketed as "SXRD" by Sony, and "HD-ILA" by JVC, the only two mainstream players currently using the technology) and LCD-RP (Liquid Crystal Display, Rear projection.) They are the leading current rear-projection (RP) HD technologies. (Pretty much anything you've looked at that isn't a flat-panel or a glass tube is one of these three.)

Microdisplays are called "micro" because they are smaller and lighter than the old CRT-based RP sets. CRT-RPs have their three projectors, along with pretty much all of their electronics, mounted in the base of the set, below the screen area. They point up toward a mirror mounted at an angle behind the screen, which reflects the image onto the inside of the screen itself. Depending on the size of the set, the working guts of a CRT-RPTV can stand over two feet tall, with the screen mounted above them.

Because the components in a microdisplay are so much smaller, and are mostly located behind the screen, the set doesn't have to be that much bigger, vertically or horizontally, than the screen itself. (Behind the screen, the depth of a microdisplay is less than that of a traditional CRT-RPTV, although obviously more than that of a "flat-screen" like a plasma or LCD panel.) So they can fit in places where CRT-RPTVs can't, and they offer room for under-set storage not available with the older designs.

Without the heavy, glass CRT guns they are also much lighter than CRT-RPTVs. (My old 56" widescreen analog Toshiba CRT set weighed over 300 lbs. My new 56" JVC HD-ILA, just under 100 lbs.)

#15 of 27 OFFLINE   ChrisWiggles

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Posted May 30 2007 - 11:09 AM

Crappy source signals, crappy setup, etc. Best Buy, CC, Costco are not places to see good images. The kids working at these places have no clue, you think they know anything about framerates? It's a disaster in there.

#16 of 27 OFFLINE   alphanguy

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Posted May 30 2007 - 04:10 PM

Joe, I know in my post, I wasn't referring at all to RPCRT, I was talking about good old fashioned DIRECT VIEW CRT. I will visit the high end store myself and see if anything is different. New technology isn't always better, many times it's just more compliacted and expensive to repair. I just chalk it up to people not noticing or caring about how something truly looks, they just want an expensive new "toy" to play with, even if it is an easy bake oven instead of a jennaire. Just look at how many people watch 4:3 material stretched out on their new 16:9 sets and don't seem to care. I, for one, don't want every person on my tv screen to look like theyv'e been attacked by silly putty. It's the same people who aren't bothered by the network "bugs" in the corner of the screen. The rest of us see it as something akin to sitting across from someone at dinner with spinach in their teeth.

#17 of 27 OFFLINE   PaulDA

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Posted May 31 2007 - 01:02 AM

The limiting factor for CRT Direct View HD displays is size. At the average seating distance of 10 feet, ALL such TVs are small and for those who are seeking a more immersive experience, they are not worth considering. Moreover, they won't be available for much longer, so if you plan to ONLY use one of those, better buy some spares. If a direct view CRT was available in 16:9 with a 50 inch diag. screen, I would (and many others, likely) consider one--but there is no such beast nor will there be.
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#18 of 27 OFFLINE   alphanguy

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Posted June 01 2007 - 05:29 PM

Yes, I guess the size would be the limiting factor for some. For me, I want a TV large enough to enjoy, but small enough that it isn't the first thing you notice when you walk into my home.... and in my living room, the TV is NOT the center of attention unless it's turned on.

#19 of 27 OFFLINE   LanceJ

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Posted June 02 2007 - 03:43 PM

Fun factoid: the largest direct-view CRT you can get:

40" FD Trinitron WEGA® XBR

I didn't realize they still sold these. I saw one at Tweeter about three years ago, man was it BIG. Standing in front of that huge glass screen made me think of all the air pressure it was holding back. Posted Image

BTW: IIRC in the broadcast biz they still use CRT displays to make sure what's going out over the airwaves looks right.

#20 of 27 OFFLINE   David_p_S

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Posted June 05 2007 - 07:11 PM

All this great discussion aside, I think the reason you notice the noise in the picture in the store is due to viewing distance. In the store you are generally able to walk around looking at all the 50+" displays from about a foot, and that's just too close. Back up to 8 or 10 feet and you'll notice no noise.