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Discussion Starter · #1 ·
This may sound strange, but yesterday for the first time I checked out the ATI DVD player and couldn't get it to work at all.


With no DVD disc in the drive, the DVDplayer opens just fine. I then inserted the Rush Hour title, and the system (WinMe) hung completely. When I rebooted, I tried to play the DVD thru an old version of WinDVD - no problem at all. So I tried the ATI player again, and once again the system hung completely.


After rebooting, I tried a 2nd DVD title (Fifth Element), and though this one actually played, there was only sound, no video. On closing, I tested again with WinDVD and it played fine.


So what stupid thing have I done or neglected to do?
 

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Whatever you do, just make sure you unregister the WinDVD direct show filters for the ATI player (in DVD Genie) to work right. It does take a fresh boot between playing different DVD's with the ATI, in any case. [there was no msdos.sys by the way].


Carey
 

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Try DVD Genie to set up the ATi player, check this post:
http://www.avsforum.com/ubb/Forum12/HTML/008956.html

Unregister WinDVDs filters thru DVD Genie first....unregister, then click "apply", then "run" to set the values in the registry. Then set up the Ati player (using the Cinemaster tab), click "apply", then switch to the ATi/Matrox tab & click "run ATi" to apply the settings.

You can get DVD Genie here:
http://www.inmatrix.com

The ATi player is picky about Region selection also...I believe it is Region 1 DVDs only...but don't quote me on that! http://www.avsforum.com/ubb/smile.gif


------------------

Wayne Harrelson

Springfield, Va
http://www.geocities.com/wayneharrel...HTPC_Page.html

http://www.mp3.com/karnis




[This message has been edited by Karnis (edited 04-28-2001).]
 

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Discussion Starter · #5 ·
A different question: has anyone else noticed that, while the Gamma slider has some 40 odd increments, there are actually only 7 or 8 *effective* steps to it?


(The other 32 increments are identical to the ones adjacent to them.)
 

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Quote:
Originally posted by Ashley Saldanha:
A different question: has anyone else noticed that, while the Gamma slider has some 40 odd increments, there are actually only 7 or 8 *effective* steps to it?


(The other 32 increments are identical to the ones adjacent to them.)
The color controls in the ATi player have a mind of their own. Check this thread:

http://www.avsforum.com/ubb/Forum12/HTML/010055.html



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Wayne Harrelson

Springfield, Va
http://www.geocities.com/wayneharrel...HTPC_Page.html

http://www.mp3.com/karnis
 

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Ashley,


You can check the thread that Wayne pointed to or I'll give you the short answer. I don't think G=+1 click does anything. G=+2 and G=+3 are the same and both of these lower the black level by over 20 mV. They also cause a noticable non linearity in the gray scale ramp with a significant inward bow. If your display was properly calibrated for black, then G=+2 or G=+3 will result in a very dark picture. I think that G=+4 and G=+5 are also the same. In this case the black level is boosted by about 10 mV, so the picture will look brighter in the blacks. There is also some non linearity with a bow in the opposite direction, but not nearly as bad as the G=+2,+3 case.


My personal opnion is that we are better off without it, see the other thread for that.



Regards,

John Moschella
 

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Discussion Starter · #8 ·
John - I read that thread with interest, and concur. You guys are testing the Gamma slider against the registry and a scope, and I'm testing the Gamma slider against the Radeon overlay gamma registers.


There are 36 increments to the Gamma slider, but their effectivity is as follows:


0 - power-on default

+1 and +2 are the same

+3 thru +6 are the same

+7 thru +11 are the same

+12 thru +20 are the same

+21 thru +29 are the same

+30 thru +32 are the same

+33 thru +35 are the same


Only 8 effective increments...
 

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Ashley,


Well, that makes sense from what I've seen and measured, although I never went past +5 with the scope measurements. I suspect increasing non linearities with higher settings, however that's just conjector at this stage.


John
 

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Quote:
Originally posted by John Moschella:

I suspect increasing non linearities with higher settings, however that's just conjector at this stage.[/b]
but that's what Gamma corrections are supposed to do, Gamma creates non-linearities in the voltage signal so that you can generate a signal that "looks" linear to the human eye.


there is nothing inherently bad about non-linearity in the voltage signal as long as you get a range of luminance values that appear linear to our eyes.
 

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Quote:
Originally posted by Jim Tittle:
but that's what Gamma corrections are supposed to do, Gamma creates non-linearities in the voltage signal so that you can generate a signal that "looks" linear to the human eye.


there is nothing inherently bad about non-linearity in the voltage signal as long as you get a range of luminance values that appear linear to our eyes.
Jim:


I'm glad you pointed that out because for a minute there I was getting worried that these recommendations to leave gamma at default and out of the equation for tweaking the best possible picture may have built credence. I just couldn't for the life of me understand how we all would have been better off leaving it alone when it represents the most advantageous tool handed to us yet for HTPC dvd PQ.


[This message has been edited by MikeM (edited 04-29-2001).]
 

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Mike,

The catch is that you can't just turn the gamma up because it changes the black level. I think that the biggest percieved "advantage" of G=+4 is increased shadow detail and that comes from the black level voltage increase, not the nonlinearity which is very slight as I pointed out. If you want to try G=+4, set B=+3 and C=-2 so you have about the right black level voltage. Calibrate your display using these settings and see if you like the picture.


John
 

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Quote:
Originally posted by John Moschella:
Mike,

The catch is that you can't just turn the gamma up because it changes the black level. I think that the biggest percieved "advantage" of G=+4 is increased shadow detail and that comes from the black level voltage increase, not the nonlinearity which is very slight as I pointed out. If you want to try G=+4, set B=+3 and C=-2 so you have about the right black level voltage. Calibrate your display using these settings and see if you like the picture.


John


Thanks John, that sounds reasonable to me and more accurate. I'll give it a go tomorrow night. Now, if I could only find a way to make them stick. Also, John, I would like to make a reg. patch like theone S.Smith sent me and you have as a shortcut to your desktop except the one I have now is gamma 0, bright +4, contrast -3.... I need to know the values for gamma+4, bright =3, contrast -2....saturation and hue stay the same.



[This message has been edited by MikeM (edited 04-29-2001).]
 

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Quote:
Originally posted by John Moschella:
Mike,

The catch is that you can't just turn the gamma up because it changes the black level. I think that the biggest percieved "advantage" of G=+4 is increased shadow detail and that comes from the black level voltage increase, not the nonlinearity which is very slight as I pointed out. If you want to try G=+4, set B=+3 and C=-2 so you have about the right black level voltage. Calibrate your display using these settings and see if you like the picture.


John
Could you post the registry values for these settings, please? Thanks....




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Wayne Harrelson

Springfield, Va
http://www.geocities.com/wayneharrel...HTPC_Page.html

http://www.mp3.com/karnis
 

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MikeM,


When I was doing these measurements with a scope I was NEVER successful in setting the gamma in the registry and having it come out the same as +4 clicks. It seems that the +4 clicks is gamma=50 (decimal) in the registry, but when I set the registry to this prior to starting the player it never came out right. So you have to use the sliders which is what I did last night while checking out the gamma=+4 setting.


Has anyone been able to set the gamma in the registry?


John
 

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Quote:
Originally posted by John Moschella:
MikeM,


When I was doing these measurements with a scope I was NEVER successful in setting the gamma in the registry and having it come out the same as +4 clicks. It seems that the +4 clicks is gamma=50 (decimal) in the registry, but when I set the registry to this prior to starting the player it never came out right. So you have to use the sliders which is what I did last night while checking out the gamma=+4 setting.


Has anyone been able to set the gamma in the registry?


John


Okay, so now we're at a crossroad between where you sit and where Cliff sits on this issue. Let me sum up if I might: You prefer to set gamma according to a preset bright+3, contrast-3 scenario while Watson suggests setting gamma against a 0IRE background of contrast and brightness at default. Right so far?


So, what's need then are any new registry value equivalents to make a more up to date dot reg file. I have one already, but that was when you were experimenting with +4 brightness, -3 contrast and 0 gamma.


As Regis would ask: What's your final answer?

 

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â€Okay, so now we're at a crossroad between where you sit and where Cliff sits on this issue. Let me sum up if I might: You prefer to set gamma according to a preset bright+3, contrast-3 scenario while Watson suggests setting gamma against a 0IRE background of contrast and brightness at default. Right so far?â€


Mike,


Actually I never said that my final settings are at the defaults. What I said is that the contrast and brightness have been scope calibrated to obtain maximum peak white level while maintain the black level at 0 IRE and then the Gamma is adjusted to obtain fine details in dark scenes.


I can’t say that John’s approach to calibrating the Radeon is wrong either. It may be slightly more complicated than mine, but the end results is to obtain good picture quality, whatever you use to get to the final settings. My objective was to create a balance between DVD overlay, the desktop, and HDTV using the same settings on a projector.



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Best Regards, Cliff

Digital Connection, LLC

[email protected]
 

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The one point I would want to make here is that it is theoretically and practically *impossible* to calibrate Gamma using only voltage readings from the card. Gamma has to be calibrated with a Spectral Photometer or, in the worst case, the eyes of a human observer. The purpose of Gamma is to create a luminance ramp that appears to have a linear *brightness* gradient, and no oscilliscope measures brightness last time I checked http://www.avsforum.com/ubb/smile.gif


So while the techniques described are excellent for setting the black level, they do absolutely nothing to help you set the proper Gamma value. That step has to be done by measuring the light coming out of the projector.
 

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Jim,


I don't believe that either John or myself have ever stated that we used a scope to adjust the gamma.


Because very few (if any) privately owned home theaters can be considered a Visual Research Lab we will just have to settle for second best and adjust gamma in our HT by eyeball to obtain the best image quality possible (for us).



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Best Regards, Cliff

Digital Connection, LLC

[email protected]
 

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Quote:
Originally posted by Cliff Watson:
I don't believe that either John or myself have ever stated that we used a scope to adjust the gamma.
In your case that is certainly true, but in John's post here or in the other thread he clearly implied that based on his measurements the Gamma should be left at 0. This could be very misleading for someone who doesn't know the true function of the Gamma setting (as John himself admitted he didn't really know the purpose of the Gamma function). These kind of measurements described by you and John are very useful, and I and many others appreciate your efforts. However, I thought it was important that inexperienced users were not left with the impression that these voltage measurements could tell you how to set the Gamma function. Cliff, you are obviously very knowledgable about home theater, and I know that you are already aware of this, but I was posting a warning for the less experienced reader here who could easily have been confused by some of John's original statements about the Gamma function.


It was not my intention to offend, but only to point out certain facts about the Gamma function so people newer to home theater would not inadvertently come to the conclusion that the Gamma setting of 0 was optimal.
 
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