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 Post subject: Leo Bodnar crt testing
PostPosted: Sun Mar 19, 2017 9:50 pm 



Joined: 04 Jul 2010
Posts: 146
Quite a while back I came across this discussion on crt vs lcd for lag testing and in one case they were doing something about catching the process as the picture was being "drawn" on the screen. It had concluded that the crt actually did in fact have a frame delay in putting the complete picture on screen and it shocked me that the lcd they were using was actually faster, thus breaking the myth that crt's are lag free and better then any panel that's on the market.

I couldn't find this article as I believe it's been taken removed or something, so I'm issuing a challenge to anyone who wants to try this out where anyone who owns a Leo Bodnar can test this directly on a standard crt. If there is any sort of delay, I would be interested in seeing if this myth can indeed be "BUSTED".

Doing so may give us a different view on how we look at panel technology from this point forward.
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 Post subject: Re: Leo Bodnar crt testing
PostPosted: Sun Mar 19, 2017 10:31 pm 


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Location: Kentucky
LCDs draw the screen from top to bottom too. The lowest lag you can have is 0ms at the top and 16ms at the bottom (assuming a 60Hz display), this goes for both CRTs and LCDs.

LCDs aren't faster than CRTs.


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 Post subject: Re: Leo Bodnar crt testing
PostPosted: Sun Mar 19, 2017 10:40 pm 



Joined: 04 Jul 2010
Posts: 146
This is correct.

But while we're talking about the majority of lcd's, another forums (SRK) has been quite anal about monitors that are sub 1-frame for their fighting game tournaments and they had quite a few that were listed. Other pc sites have listed a few as well, including some premium models from ASUS and BenQ. When crt tests show that the milliseconds are on par with their panel counterparts and a Leo Bodnar says they still have lag otherwise, then it puts crt's credibility into question.
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 Post subject: Re: Leo Bodnar crt testing
PostPosted: Sun Mar 19, 2017 11:19 pm 


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A monitor with "sub 1-frame" of delay would be one with less than 16ms at the top of the screen and less than 32ms at the bottom.


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 Post subject: Re: Leo Bodnar crt testing
PostPosted: Sun Mar 19, 2017 11:38 pm 


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Location: Canada
A directly driven CRT is letting the video signal drive the electron gun, displaying the signal as it is sent out by the video source. This is considered to be zero latency, as there is no delay in between the video source sending a signal and that signal being displayed.

An LCD panel could approach this level of latency if the display controller updated the display top-to-bottom as the signal was arriving, but it could never be faster than a directly driven CRT, because that would require the LCD panel to display the signal before the video source sends it. The laws of causality would have an issue with that.

There are CRT displays that feature digital processing that is similar to an LCD panel, where they store one or more frames in memory before drawing them to the screen. CRT HDTVs are a typical example of this, and it's definitely possible to have LCD displays that have lower latency than such a CRT display. However, this is usually not the case for 15 kHz CRTs, and for PC monitors.


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 Post subject: Re: Leo Bodnar crt testing
PostPosted: Mon Mar 20, 2017 1:55 am 


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No test is perfect. The Leo Bodnar is no different... but, the results can come in handy.

Here's a CRT monitor. Nice direct image without buffering.

No lag here. The 720p image is letterboxed, so the "bottom" comes out under 16ms.

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Spoiler: show
Image


Bottom
Spoiler: show
Image
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 Post subject: Re: Leo Bodnar crt testing
PostPosted: Mon Mar 20, 2017 3:12 am 



Joined: 04 Jul 2010
Posts: 146
Somewhat better then I predicted. 15.1 ms to draw the entire frame.

When I was reading about those sub 1 frame monitors that they use for the EVO championships being that they rate 3 ms or better, I'd imagine running comparison tests would be like a turtle and hare race where the crt gets off to an early start. This is exactly what I was reading about from the article before I lost track of it.

So aside from the whole retro thing, crt's are clearly irrelevant now? I don't think they are entirely, but I don't really think anyone's argument that lcd's are worse then crt's for gaming holds water anymore, at least not unless they aren't smart enough to buy a better display to begin with.....

Better yet, I don't think the retro SMASH community has a point to their beliefs in lugging crt's around either. :)
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 Post subject: Re: Leo Bodnar crt testing
PostPosted: Mon Mar 20, 2017 3:42 am 


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headlesshobbs wrote:
Somewhat better then I predicted. 15.1 ms to draw the entire frame.

When I was reading about those sub 1 frame monitors that they use for the EVO championships being that they rate 3 ms or better, I'd imagine running comparison tests would be like a turtle and hare race where the crt gets off to an early start. This is exactly what I was reading about from the article before I lost track of it.

So aside from the whole retro thing, crt's are clearly irrelevant now? I don't think they are entirely, but I don't really think anyone's argument that lcd's are worse then crt's for gaming holds water anymore, at least not unless they aren't smart enough to buy a better display to begin with.....

Better yet, I don't think the retro SMASH community has a point to their beliefs in lugging crt's around either. :)


CRT's have no rival. You're talikng nonsense.

The letterboxed 15.1ms you see near the bottom of the screen is a perfect score. It takes 16ms to draw a frame. 16ms multiplied by 60 frames equals (about) one second. Therefore, to draw 60 frames a second, each frame takes about 16ms.

Perfect score. Zero lag. That was perfection.

Let's boil this down for you:

Each line on a CRT appears and disappears almost instantly. That allows for perfect motion. No blur and no ghosting. Brightness doesn't affect anything. Draw as bright or dark as you like, it all fades to black instantly after each draw.

LCD's take time to light up and turn off. They take much longer. The CRT practically lights up pixels and turns them off instantly. By comparison, the LCD is very slow.

The results are ugly. It takes longer to draw the screen. The LCD has a delay before it can draw the signal it receives. This is lag.

The LCD pixels also need to time to light up and fade out. This leaves a blur behind moving objects, because the image is changing faster than the LCD pixels can change. The LCD can't keep up. Pixels are caught trying to change color, but they can't do it fast enough. You can try to hide it by strobing the backlight, but you can't make it go away. LCD pixels change color slowly and sometimes the image will move faster than the pixels can change. This is absolute and beyond reproach. This is a cold hard fact. This is motion blur.

To battle motion blur, you can choose lower the brightness and restrict the available colors. That way, the LCD pixels can change faster, because they don't have to be as bright. (CRT's have perfect motion no matter what.) The LCD can be faster by reducing the brightness, but it's still slow. Also, you just got yourself an ugly dark washed-out display with dull colors. This is ghosting.

Let's ignore all the filters and scaling. The reason these other digital flat panel technologies suck is their inability to quickly draw bright colorful images. The CRT can simply produce each frame almost instantly--without any concern about the last frame. CRT's draw very fast and they start each frame with a "clean slate". No digital panel technology can do that.

Hope this helps you understand.

Digital displays draw slow and the last frame lingers. That sucks.
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 Post subject: Re: Leo Bodnar crt testing
PostPosted: Mon Mar 20, 2017 7:14 am 


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SRK have been making unverified statements over the lag of displays for ages, it's not funny people still read them.
Those so-called 'EVO monitors' have since the beginning been nothing special at all, not even for the lag, there are plenty of near-zero lag monitors out there, bigger and with much better image quality. There are enough good and reliable monitors reviews on the internet to compare, why do droves of people just buy the same crap just one guy over a community or a show say "its the best" ?
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 Post subject: Re: Leo Bodnar crt testing
PostPosted: Mon Mar 20, 2017 7:39 am 



Joined: 04 Jul 2010
Posts: 146
e-pen points I take it?

The ones I'll take for the best verification are from those I've seen on displaylag which are going at least 10 ms. Of course I have links to a few others, but what really interests me are when people do that stopwatch test and they get those pics with the exact same number. I think I'd like to try those out.
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 Post subject: Re: Leo Bodnar crt testing
PostPosted: Mon Mar 20, 2017 8:29 am 


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headlesshobbs wrote:
e-pen points I take it?

It's misinformation/lack of knowledge, and, well...internet.

- Displaylag average the three bodnar figures, I don't like their method because you can't see the one that matters most: the top bar measurement.

- The stopwatch method has been dodgy for ages for several reasons, people using wrong displays to compare (even a second lcd or laptop), and discrepancies because of scripts messing up the very stopwatch timing. But that's the middle ages of camera methods, the SMTT 2.0 software method is more reliable and serious, though few people actually use it.

- Leo Bodnar tester is good too but not everyone uses it the same way (some reviewers don't even make clear what figure they give).

If you want reliable information on how monitors really perform, don't trust community posts or 'commercial claims' too much, in place read the reviews of websites like;
tftcentral.co.uk
pcmonitors.info
wecravegamestoo monitors forum

tftcentral and pcmonitors also have in-depht articles to help understand how displays work, extremely useful.
At first it takes some time and a bit of effort maybe to understand some stuff but it's no rocket science either. Once you get the essentials you won't believe all the bullshit sellers and people tell about displays.

Also in foreign languages but with understandable test results (or google translate if necessary);
http://playwares.com/dpreview
http://www.prad.de/new/monitore/index2.html
http://3dnews.ru/display/lcd
http://www.sweclockers.com/tester/skarmar
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