Author Topic: LCD flat panel - 100 Hz - worth while?  (Read 2272 times)

Lexje

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LCD flat panel - 100 Hz - worth while?
« on: April 04, 2008, 11:04:36 am »
Hi forum,

Preparing to buy a LCD flatscreen, not sure yet between 42" and 46" probably 46".
Apparently 100 Hz technique has also entered the LCD world.

Can anybody tell me if this  technique is worth its money?  ???
Comparing to 'classical' TV sets, the 100 Hz produced a 'less flickery' image, as the flickering became invisible to the human eye.
I cannot imagine the benefit would be the same to LCD. After all I'm using plenty of LCD's connected to PC's around, these don't seem to flicker, and they don't use 100 Hz technique...

Awaiting your comments.

Best regards,  :D

Erwin
« Last Edit: April 08, 2008, 10:12:46 pm by Lexje »

jtgamble

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Re: LCD flat panel - 100 Hz - worth while?
« Reply #1 on: April 04, 2008, 11:36:10 pm »
The 100Hz LCD's will probably be best suited for you if you A) play lots of video games on them or B) watch lots of fast paced sports. Those are the places you will (maybe) notice a difference. If you don't do either of those, you're probably just as well going with whatever is cheaper. I did a lot of research into these before I bought my TV - i wanted a 100Hz set, but they were just too new/expensive at the time when I made my purchase. Hope that was helpful :)

maybeoneday

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Re: LCD flat panel - 100 Hz - worth while?
« Reply #2 on: April 05, 2008, 09:15:22 am »
Hi Lexje,
as jtgamble says it's really down to personal use -I've just got a sharp (Aquos lc46X20) and in the shop it was right at the side of the latest 100Hz Sharp : the only difference i could see, after a lot of  comparison with different inputs & media (thanks Mr.Salesman ! ) was on very fast changing pictures eg. motorcycling vid.Not enough for this yorkshireman to part with the extra £250  ' )
regards
Ian

Lexje

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Re: LCD flat panel - 100 Hz - worth while?
« Reply #3 on: April 08, 2008, 10:17:07 pm »
Thx Guys,

As a matter of fact my choice would also be the Sharp Aquos 46", either 100Hz or not...

Thanks,

Erwin

jtgamble

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Re: LCD flat panel - 100 Hz - worth while?
« Reply #4 on: April 09, 2008, 01:23:36 am »
Nothing to do with the 100Hz thing, but I'd highly recommend looking at the 47in westhinghouse TX. Thats what I ended up with. Its been wonderful so far, and was quite a bit cheaper than the Aquos at the time I got it anyway.

http://www.westinghousedigital.com/details.aspx?itemnum=126

If you wanna save a few bucks and have a great TV, take a look :)

(sorry for a bit off topic)

Viking

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Re: LCD flat panel - 100 Hz - worth while?
« Reply #5 on: March 06, 2009, 03:09:22 pm »
Hi,

I am short before buying a TV for LinuxMCE, but the last thing I have to decide is if I need 100hz or not. Decision is between sony KDL-46W4500 and KDL-46W4000 (without 100hz). Yes I know it has no serial, but as I am not going to use more than one input and if, then I will control it with the USB-UIRT.

I am only going to use this 46" TV for LinuxMCE and nothing else. So the question is if there will be any advantages with 100hz and DVI/HDMI input ?
Have you guys with a 100hz TV tried turning 100hz off to see if there is  a difference ?
Or noticed anything noticable ?

My MD is using an Nvidia 7300GT with DVI out.

Thanks in advance :)
Viking

colinjones

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Re: LCD flat panel - 100 Hz - worth while?
« Reply #6 on: March 06, 2009, 08:43:53 pm »
Seriously Viking, 100Hz on an LCD is going to make bugger all difference... certainly not worth any extra money for it! (charging extra for this is robbery anyway for various reasons!) LCD display technology is nothing like CRT and doesn't suffer from the same issues. CRTs' phosphorous gets hit by the beam and glows briefly before fading again. This light-up time, and time-to-fade had to be critically timed so that you got a quick response, and long enough 'glow' but had faded enough in time for the next scan. Phosphor is passive of course, so inherently there needed to be a 'dark' period in between scans... it can't just instantly turn off ready for the next pass! This dramatically emphasised the flicker. The best way of reducing this was to make it fade twice as fast, but double the scan rate - thus minimising the 'dark' period.

LCDs are active - they have a light behind the LCD which shines through continously, and each pixel is 3 coloured transistors that are set to different levels of tranparency. So there is never any 'dark' period. Of course there are still issues of basic refresh - the more frames per second the smoother the motion, but all sources are basically 24/25/30/50/60fps, typically 25 or 30... so refreshing the screen 100 times per second isn't going to benifit you, really. For LCD the more critical issues are contrast ratio (try for at least 10,000:1), response time (try for 8ms at most, 5ms, better yet), and how even the black level is on a completely black screen with the lights down (the transistors are never completely identical - on cheaper LCDs this can result in patchiness when they are trying to block all the light from the backlight. Obviously, you also want the blackest level possible with this screen)

These parameters, or better will give you a well defined colour in your picture, viewable in all lighting conditions and with movies that have lots of dark scenes, and will also ensure that movement is clear an unblurred. The only other thing I would say is, beware that many manufacturers say their panels are HD when in fact they are nothing of the sort! Often only 1366x768 - you need to find the "Native Resolution" of the panel and this can sometimes be difficult... don't rely on the salesperson, ask for the manual! Just because a display can display a 1080i/p image doesn't mean that is its native resolution.

EDIT: forgot to answer your other question. Yes HDMI/DVI are definitely a big benifit for image quality. Definitely do not use svideo or composite connections. Component as a worst case. Avoid VGA, ideally use HDMI or DVI (the same thing as each other for video, so you can use convertor cables without loosing any quality - on that subject, don't be stiffed into buying expensive HDMI/DVI cables... salespeople will tell you it can effect the quality - it can NOT! It is just as digital as a Cat6 cable, ie it either works or it doesn't... if it doesn't you will see immediately that on screen! $10 max for a cable)
« Last Edit: March 06, 2009, 08:48:12 pm by colinjones »

hari

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Re: LCD flat panel - 100 Hz - worth while?
« Reply #7 on: March 06, 2009, 10:45:15 pm »
mostly correct, but VGA (RGBHV) has better quality than component (but they are pretty close). Btw, you don't wanna know what manufacturers do with the signal inside the TV. Barely any TV has full digital processing. Guess how the analog signal propagates, correct, component or RGB. So for short runs, with good component cables and most TV sets, there is not much difference between HDMI and component. I also agree with the "picture quality" of HDMI cables. If you get a correct signal, there is absolutely no difference between the 300 buck monster cable and the $5 radioshack cable. It is just that some cables have better shielding than others. This can help on long runs. No, they don't use golden twisted smurf hair in the expensive one to give you a better picture.

Btw, does somebody need a Spatz HDMI-MAX active HDMI repeater?

EDIT: my dad has the 4500, _very_ decent picture with PAL signals. I'd say plasma quality. I was quite impressed (and I did not see a point in interpolating frames till then).

br, hari
« Last Edit: March 06, 2009, 10:48:38 pm by hari »
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Viking

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Re: LCD flat panel - 100 Hz - worth while?
« Reply #8 on: March 06, 2009, 11:14:36 pm »
Hi Colin,

thanks for your feedback :)

"They" (Sony & co) say that with 100hz they calculate pictures inbetween the existing so that movies that would normally have judder would "flow" on a 100hz LCD. But probably on cost of some picture disturbance... Also some tests say that they are better - no judder.

But I did not find anything out on what kind of sources would be without judder. I assume that it only works on analog sources or PAL resolution scaled up - but does anyone of you know that ? I would hate buying a LCD without 100hz and then find out that it has judder ...

I saw the W4000 in a store (Bilka) here where I live and with a (I assume) HD signal and there were a two people filmed a bit from below walking throgh a shopping hall or something like that and the ceiling had judder :( So is this becasue of bad splitter/connections to the TV (same picture on several LCD's) or what could it be ?

They have both got FullHD resolution (1920x1080) 33000:1 (w4000) and 50000:1 contrast ratio and 8ms.


Regarding HDMI cable. I thought so - it is digital ;) but thanks for confirming. BTW. the same thing goes for what they call "very good" digital audio cable - what should be the difference here ? it is also digital - so why should the 100$ cable be better that the 10$ ...

Greetings
Viking

Viking

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Re: LCD flat panel - 100 Hz - worth while?
« Reply #9 on: March 06, 2009, 11:17:24 pm »
HI Hari,
EDIT: my dad has the 4500, _very_ decent picture with PAL signals. I'd say plasma quality. I was quite impressed (and I did not see a point in interpolating frames till then).
OK, good to know if I should use it for PAL signals some day :)

Did you try disabling the 100hz (MotionFlow) on the TV to see what happens with HD TV signals (if he has got any ;)) ?

Greetings
Viking

hari

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Re: LCD flat panel - 100 Hz - worth while?
« Reply #10 on: March 06, 2009, 11:44:13 pm »
no HD sources yet (was the reason why he got a set with decent 50Hz PAL performance). I'd assume it could make a difference for 1080i. But I don't see how it should affect progressive formats.

best regards,
Hari
rock your home - http://www.agocontrol.com home automation

colinjones

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Re: LCD flat panel - 100 Hz - worth while?
« Reply #11 on: March 07, 2009, 01:40:25 am »
hari - agreed on the VGA vs HDMI, that was a subjective call based on my concern over cross-talk, but a decent VGA cable shouldn't present this issue...

Viking - I would naturally be dubious or sceptical of those sorts of interpolation claims. In theory, if you could accurately interpolate then it would improve the smoothness on fast movement. In practice, the kind of processing maxtrix required to do this well, particularly when it is only a part of the screen moving (ie not a pan) can easily lead to corrupting the image more than you solve the motion judder. Technologies that do video processing in TVs have a very checkered history! Witness MotionPlus in Samsung TVs (mine), universally the public hates the awful effect it has on picture quality and everybody turns it off! Not an absolute, just a "beware!"

On the example you saw - be careful again, the issue is there are overlaying effects. In my experience, by far the greater quantity of video artifacts come from digital compression rather than the screen itself. eg MPEG2, etc. These compression technologies also include motion prediction (used to do your interpolation) used for temporal compression delta techniques. There isn't just one way of doing it - a sloppy or cheap compression can produce similar looking artifacts long before the image gets to your TV, by which time it is uncorrectable. High quality DVD compression and mastering is typically done with vastly more care because it doesn't need to be real time compressed like a TV broadcast does. Thus you see even more variation in DVD quality between companies that compressed with great care and cheap knock offs or cheap releases. Moral of the story is, pick a good source that really tests the machine, then use that same source every time for comparison between units.

Final word on quality cables and not getting scammed - don't let them fool you into thinking one cable is better than another (even with the golden smurf hair! rotfl) just because it has gold plated connectors or even the wire itself! Gold is actually a significantly worse conductor than copper (32% worse in fact!), and silver is better again - it is the metal with the best conductivity of all. The only legitimate excuse for using gold is that, unlike silver and copper, it doesn't corrode as easily.... clearly this is no reason to use it as the wiring, and is of dubious excuse to use as the connectors unless you intend on unplugging and replugging them on a regular basis.

Have fun!

Viking

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Re: LCD flat panel - 100 Hz - worth while?
« Reply #12 on: March 07, 2009, 11:48:12 pm »
Hi Hari, Hi Collin,

Thanks for your input  :)

I was in the store today again *bilka( and this time they had the kdl46w4000, a kdl40w4500 and a kdl37w4500 next to each other playing the same hidefinition movie. And interesting enough the w4000 had judder on all movements and both w4500 was smooth ...

So I am now really thinking about getting the w4500 to be sure that I have no judder even if it is 400euro higher price. But maybe ill go for the 40" w4500 instead as it has the same price as the 46" w4000.

Greetings
Viking

Viking

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Re: LCD flat panel - 100 Hz - worth while?
« Reply #13 on: March 08, 2009, 11:48:54 pm »
Hi again,

colin - thanks for clarifying that it could also be the source material that was not quite good. That was something i had not thougt about.

Forgot one thing that a sales man in another store told me. The w4000 has a 60hz LCD and the w4500 has got a 100hz. And the w4000 converts everything up to 60hz
So am I right in assuming that when using PAL and european HD we have 25 fps so converting to 60 hz would not be that nice ? While setting the video out to 50hz with the w4500 would just double it to 100hz and everything shoukd be nice ?

Or am I wrong here ?

Greetings
Viking

colinjones

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Re: LCD flat panel - 100 Hz - worth while?
« Reply #14 on: March 09, 2009, 12:03:14 am »
hmmm... depends what is actually mean by converting the frame rate. Theoretically, you could interpolate between 25fps and 60fps, but with each interpolation the errors will accumulate... I can't imagine the end result would be very nice! You are right, frame/field doubling is quiet easy... but again, this does nothing for picture quality on an LCD (CRT, certainly) unless it somehow predicts motion between the original frames to infer more content than is available from the original. And with that, note my original caution!

Personally, I would be very surprised if the 60Hz model even attempted to upconvert from 25fps or even 50fps to 60. I would go to the manufacturers web site and download the manual and specifications.. rely on that, not what the salesman tells you :)