JudderTest software - AVS Forum
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post #1 of 255 Old 10-26-2003, 01:21 PM - Thread Starter
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JudderTest is a software tool for testing how well projectors can handle varying refresh rates. It is useful for fine-tuning your PowerStrip settings to minimize judder and tearing artifacts.

The ideal projector will handle several refresh rates natively, without any frame rate conversions. Unfortunately, most digital projectors are limited to just one native refresh rate. My motivation for writing this tool was to put the spotlight on this issue and increase awareness among consumers.

You can download the zip-archive from this location:

JudderTest 1.1

Much of this thread deals with the beta-version of this tool. Click the following link to fast-forward to more recent times:

Announcement of JudderTest 1.0
Announcement of JudderTest 1.1

Happy tweaking!
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post #2 of 255 Old 10-27-2003, 02:00 AM
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Excellent!
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post #3 of 255 Old 10-27-2003, 09:44 AM - Thread Starter
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I think I should have included a couple of standard DLLs (I always forget them!). If anyone's having problem even starting the tool, let me know...
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post #4 of 255 Old 10-28-2003, 04:59 AM
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Good program, I tried it out and on my PC monitor it shows a solid bar that is not juddering. On my projector it shows a bar that is not juddering either but it all broken up. Any idea what this means?
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post #5 of 255 Old 10-28-2003, 05:25 AM
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I am a bit confused. The bar moves at 60 frames per second... well on a 60hz monitor that should sync.. Isn't the issue all about movies being shot at 24 frames per sec and then converted in the PJ to 60 frames per sec?

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post #6 of 255 Old 10-28-2003, 07:18 AM - Thread Starter
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Quote:


Originally posted by GladHeAteHer
Good program, I tried it out and on my PC monitor it shows a solid bar that is not juddering. On my projector it shows a bar that is not juddering either but it all broken up. Any idea what this means?

You mean part of the bar is a bit ahead / part of the bar is lagging behind? How many parts are there?
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post #7 of 255 Old 10-28-2003, 07:54 AM
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On the projector it looks as though it is broken up into 3 parts. On the CRT monitor it looks like a solid line. The parts are not spread far apart, it almost looks like a solid line, but you can clearly see where it is broken because the edges don't match up and there's a tear line between them. Each part is slightly ahead of the next.

I'm using an Infocus LP250-A

I'll try some other refresh rates and see what happens.
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post #8 of 255 Old 10-28-2003, 08:17 AM
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At 60Hz it's broken into 3 parts, at 120hz it's broken into shitloads, at 62hz it's still broken into 3 parts, but they move down the screen. I'm going to keep on trying rates until I find where it stops. I'm going to use Powerstip to try it at 50 now.
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post #9 of 255 Old 10-28-2003, 08:41 AM
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I used powerstrip to cylce through refresh rates. Woohoo! 62.203Hz!!! Thankyou oh thankyou thankyou. When I set my PC to this refresh rate movies that used to have tearing in them for no reason display absolutely perfectly!! Thankyou. No-one up till this point has been able to figure this out for me. Yes with PAl there is now a slight judder, but it is no where near as bad as the tearing I was getting.

http://www.avsforum.com/avs-vb/showt...71#post2853771
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post #10 of 255 Old 10-28-2003, 08:44 AM - Thread Starter
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Quote:


Originally posted by FriarTuck
I am a bit confused. The bar moves at 60 frames per second... well on a 60hz monitor that should sync.. Isn't the issue all about movies being shot at 24 frames per sec and then converted in the PJ to 60 frames per sec?

That's the issue, yes. If you configure your computer to output 48Hz or 72Hz your monitor will sync to that frequency and render 48/72 frames per second. In the old days these were called multi-sync monitors as opposed to fixed-sync monitors that would only accept one frequency.

The ideal projector should have the multi-sync behavior all the way out to the panels. Sure, all projectors accept many frequencies, but somewhere along the path most are actually fixed frequency.
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post #11 of 255 Old 10-28-2003, 08:51 AM - Thread Starter
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Quote:


Originally posted by GladHeAteHer
I used powerstrip to cylce through refresh rates. Woohoo! 62.203Hz!!! Thankyouoh thankyou thankyou. When I set my PC to this refresh rate movies that used to have tearing in them for no reason display absolutely perfectly!! Thankyou. No-one up till this point has been able to figure this out for me. Yes with PAl there is now a slight judder, but it is no where near as bad as the tearing I was getting.

Hey, that's great! I suspected the program would be useful for tearing issues as well. You could try different resolutions and you may find that the non-tearing refresh rate will vary. Maybe you can find a resolution which does not tear at 50Hz and consequently does not judder either.
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post #12 of 255 Old 10-28-2003, 10:34 AM
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I haven't tried other resolutions yet, just 1024x768. The optimal refresh rate for the projector seems to be 62.53hz. I wonder if there is a manual way of adjusting the projectors fixed refresh rate. Maybe there is a trimpot on one of the boards or something. It would be good to run one at 50hz or even 100hz I'm in PAL land too.
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post #13 of 255 Old 10-29-2003, 07:01 AM
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I'm not sure clear on what to set the multipler/divider to?
My system judders slightly on 24 fps movies and I believe it's caused by the projector's fixed 60Hz refresh rate. Can this utility simulate this?
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post #14 of 255 Old 10-29-2003, 09:36 AM - Thread Starter
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Quote:


Originally posted by bluerider
I'm not sure clear on what to set the multipler/divider to?
My system judders slightly on 24 fps movies and I believe it's caused by the projector's fixed 60Hz refresh rate. Can this utility simulate this?

To see if the judder is caused by your projector, you can set your computer to 72Hz and then enter 3 as a divider. This way the bar will be drawn at the same spot for 3/72 = 1/24 second before advancing - effectively a 24 fps animation. If this judders on your projector, movies played on a software DVD player at a 72Hz refresh rate will judder too. You can also try 48Hz and use 2 as a divider.
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post #15 of 255 Old 10-29-2003, 06:31 PM
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OMFG. I've just gotten the best picture out of this thing I've ever seen. I changed the resolution to 1280x960 @ 62,250hz with powerstrip to get the bar not juddering or tearing. Played back a PAL DVD of Santana live. What a picture! No ripping!
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post #16 of 255 Old 10-29-2003, 08:06 PM
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arca - very interesting test! Given the number of posts here on judder/video stutter, I'm surprised this thread isn't more active.

Since I upgraded my HTPC a while ago, I've been getting pretty much stutter-free DVD playback. Running your test confirmed this - the bar moves across the screen (PJ is a JVC G150) with no tearing or judder at a rendering rate of 60.02 Hz.

Question - is the processing path used by your test the same as used for DVD playback (I use TT)? Do you know why GladHeAteHer would have to run at a seemingly odd 62.25 Hz to get stutter-free playback?

Thanks,
Peter
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post #17 of 255 Old 10-29-2003, 08:17 PM
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That's a good question. I'm thinking that maybe my clock in the projector is probably set to run at 60hz, but the video card clock or the projector clock (or both) are slightly out. Reclock reports the video card clock as being 62.53Hz and Powerstrip says it's 62.250Hz. Not much difference, but it shows that there might be some error.
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post #18 of 255 Old 10-30-2003, 01:25 AM - Thread Starter
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Quote:


Originally posted by GladHeAteHer
OMFG. I've just gotten the best picture out of this thing I've ever seen. I changed the resolution to 1280x960 @ 62,250hz with powerstrip to get the bar not juddering or tearing. Played back a PAL DVD of Santana live. What a picture! No ripping!

I think maybe I gave you questionable advice to change resolution. Now you have a two-stage scaling, first from the DVD's 720x576 to 1280x960 and then from 1280x960 to the projector's 1024x768. This should blur the picture somewhat and this is probably what is hiding the judder. But maybe a soft picture is preferrable over judder.
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post #19 of 255 Old 10-30-2003, 01:45 AM
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could you make the same thing with a bar that moves at 25 pixels/ second and at 30 pixels/second for Pal users ?

sorry for my poor english but I'm french !!!!
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post #20 of 255 Old 10-30-2003, 01:58 AM - Thread Starter
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Quote:


Originally posted by PeterAM
Since I upgraded my HTPC a while ago, I've been getting pretty much stutter-free DVD playback. Running your test confirmed this - the bar moves across the screen (PJ is a JVC G150) with no tearing or judder at a rendering rate of 60.02 Hz.

If your computer is set at 60.02Hz the bar will be rendered at 60.02 fps and be judder-free both on your monitor and your projector. But, a DVD is 24 fps and will be converted to 60.02Hz before leaving your gfx card. Judder will be introduced before the DVD frames even reach the projector! The tool is not fixed at 24 fps like a DVD - this can only be simulated by setting a refresh-rate of 72Hz or another multiple of 24 and then using the speed divider as described above. Perhaps I should include a fixed 24 fps option in the next version... although my goal was to find a path from DVD to projector panel that avoids any time-domain conversions.

Quote:


Question - is the processing path used by your test the same as used for DVD playback (I use TT)?

The processing path is different in two respects:
1) in the tool the frames are fixed by refesh rate and multiplier/divider setting and not always 24 fps,
2) the tool renders in RGB into the ordinary graphics memory while DVD players usually renders in YUV into a special overlay surface. The overlay is handled specially by the graphics card but ultimately converted to RGB and combined with the ordinary graphics memory before the result is output to your display device. So this difference has no effect in the time domain (refresh rates and fps), but there is a scaling step when the overlay is combined with the ordinary graphics memory which can soften the DVD frames and blur the judder. - But that's why I wrote this tool, to reveal the judder.
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post #21 of 255 Old 10-30-2003, 02:02 AM - Thread Starter
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Quote:


Originally posted by vairulez
could you make the same thing with a bar that moves at 25 pixels/ second and at 30 pixels/second for Pal users ?

You do this by altering your computer's refresh rate. If you set it at 75Hz and enter 3 as a speed divider, the bar will move at 25 pixels/second. If this is judder-free on your projector, PAL DVD's should be judder-free too.
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post #22 of 255 Old 10-30-2003, 02:18 AM
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I know what you're saying about the PC displaying the 768x576 DVD on a 1024x768 screen at 1280x960, but it does seem to hide the judder very well. Text is still easily readable. The usual 576 lines of the DVD you can see on the screen are now almost unseeable. I think I will leave these settings as my standard setup now.
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post #23 of 255 Old 10-31-2003, 05:29 AM
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I don't understand this program. Whatever the number I set in the bar speed divider box it erases whatever is in the bar speed multiplier box.
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post #24 of 255 Old 10-31-2003, 05:43 AM - Thread Starter
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Quote:


Originally posted by Kram Sacul
I don't understand this program. Whatever the number I set in the bar speed divider box it erases whatever is in the bar speed multiplier box.

That's right. It's two different ways of specifying bar speed, either you use the multiplier, or the divider:

bar speed = refreshrate * multiplier
or
bar speed = refreshrate / divider

This guarantees that the tool does not introduce judder on it's own.
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post #25 of 255 Old 10-31-2003, 06:32 AM
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Is there any way to make this program run on a secondary display?
It will only execute on my primary display (computer monitor) and I would like to use it on my secondary (crt proj).
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post #26 of 255 Old 10-31-2003, 03:13 PM - Thread Starter
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crisscross or someone with multiple displays,

could you please see if v0.3 will render to your secondary display.
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post #27 of 255 Old 10-31-2003, 03:56 PM
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i second the request to have a 24 fps setting without having to change the monitor frequency. i am running my htpc to a crt display, and thus cant set it to 72 hz without losing sync. also, when i run it, about 10% of the top of the line is missing. is that normal or part of a sync issue?

powerstirp currently shows 59.938 hz and i get occasional tearing on dvds which i would love to get rid of.

thanks,
k
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post #28 of 255 Old 10-31-2003, 07:23 PM
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Quote:


Originally posted by arca
crisscross or someone with multiple displays,

could you please see if v0.3 will render to your secondary display.

No, I am sorry to say that the program will not execute. It gives me a window:
Error: Åtgärden har slutförts (swedish) and then a window:
Runtime error! Program:...xxx\\JudderTest.exe
This application has requested the Runtime to terminate it in an unusual way. Please contact the applications support team for more information.
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post #29 of 255 Old 10-31-2003, 07:29 PM
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It's always worked on both my displays without a problem . I'm using Direct X 9 VMR9 and a Radeon 9600pro VIVO. I have dual monitors running, primary is a projector, secondary is a CRT monitor. They are running cloned.
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post #30 of 255 Old 10-31-2003, 09:52 PM
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Of course it would run in clone mode, but it will not work if you have "dualview".
Clone mode is a no go for me as I have my crt at 848*480*50HZ and that is not someting I would like to, or even could, run my primary monitor in. Clone mode for nvidia cards equals the same resolution on both displays.
Havent tried vmr9 though.

It looks like Arca in version 0.3 is close to the solution but the program shuts down for some reason.
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