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Discussion Starter #1
So I just upgraded my HTPC, and I added a blueray player.


But it seems cyberlink is expanding the levels.


I've come up with a clever work around so I can flip between input 1 (PC levels) and input 2 (video levels).


Everything should be hunky dory. I don't have great control over gamma, but HCFR shows the 10% black brighter than it shoudl be for 2.22 gamma. The issue is that the picture still looks WAY too dark. Like on PC levels, with cyberlink for DVD the THX logo doesn't even show up (PC expanded levels on PC calibrated input) .


The new video card is the integrated 8200 graphics, all it's settings for color control are off.


I can't figure out why playback of video looks so wrong and so dark, when HCFR thinks things are brighter than they should be.

 

calib.zip 11.0556640625k . file
 

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When you say "the picture still looks WAY too dark", did you watch DVD with similar measurements? I just ask to get out of the way any subjective factors like prefering more light in the image.


One basic thing I've learned about computer video playback is to check the playback program with the sort of material you'll be playing back. So if you want to set up the computer for Blu-ray playback, it's probably best to have some HD video patterns that are formatted similar to what you'll be watching in order to verify how things are being handled. An easy way is to use colorcop (or images in a paint program) to check what the playback program is doing. For a basic check you'll probably need to look at black levels, white levels, and color bars. At least checking just those three things will give you a good idea what the computer is doing with the video. It's also not a bad idea to take measurements using matching video through the playback software, but if you know exactly what the video drivers and playback software are doing you don't necessarily have to take measurements from the playback software.


From your original description you say the program is expanding, but if that's the case then I'm not clear on why you later mention a video level input. I'm also not clear on how exactly you took your HCFR measurments and if you determined that they matched how the program plays back video. Instead of even addressing those items though, if you measure video in the same way you'll be using the computer to playback then what you measure should line up with actual playback. When it comes to computer playback, either video drivers or different playback software altering black levels, white levels, or color decoding are the major items that I've had to mess with.
 

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Discussion Starter #3
The HCFR runs were done using the built-in GDI color feilds.


For input 1 (labeld -in1) I had HCFR set to 0-255

For input 2 I had HCFR set to 16-235


I also did some checking of brightness differential with MS paint and looked at some of the test patterns from spectracal. Everything that is not a DVD seems to jive and look correct.



Then I went to testing DVD playback. I know from prior experience that VMC does not expand levels, at least the application itself does not. And it looks lighter than cyberlink. But using a THX optimizer from a DVD on the PC level input with media center the center THX logo is just barely visable this is video level app w/ PC levels, this should be fairly bright and I should be able to see the shadow behind it. The looking at cyberlink w/ PC level the THX logo is completely invisible, And forget about it with Video levels, both of them are too dark.


I think the video drivers themselves might be expanding the video levels and then cyberlink expanding them again.


I'm jumping through so many hoops, because 85% of the time we are in media center and want to watch DVDs (VMC keeps video levels), when we want to watch a blu-ray we want that to look right as well.
 

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You would probably be better off pursuing this in the home theater pc area of AVS. I'm sure the people there have dealt with similar issues.
 

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Quote:
Originally Posted by sotti /forum/post/14235498


I think the video drivers themselves might be expanding the video levels and then cyberlink expanding them again.


85% of the time we are in media center and want to watch DVDs (VMC keeps video levels), when we want to watch a blu-ray we want that to look right as well.

It might be easier to just use Cyberlink for everything, but I use multiple video programs so I understand just wanting the levels to match. If either the video drivers or playback program alters video levels, it will show up in the on-screen RGB values. I'd suggest to maybe check out the colorcop program so that you can find what exactly is happening to the video levels if you want to troubleshoot this yourself. I'd figure someone has also probably dealt with a similar setup and might be able to give you an idea if it's possible to get both programs to match like sperron suggested, but even in that case it's not a bad idea to know how to double-check things and the colorcop program just gets around screen-capture restrictions that some playback software implements.


When looking at RGB results from test patterns, unexpanded black appears at 16 or 0 if expanded. Of course it's possible to alter black to appear at a variety of RGB values, but those are the most common. White has all RGB at 235 unexpanded and 255 expanded. 75% color patterns would have the relevant color at 180 and the others at 16 if unexpanded, or around 191 and 0 expanded. The reason to look at white, black, and colors is that sometimes it's possible to get black and white to display either expanded or unexpanded and the software will mess up color decoding. For example say you're using unexpanded levels, then you should expect for 75% colors to have relevant RGB values of 178-182 (+/- 1 or 2 to account for rounding errors), but if you get much more variation than that (for example a difference of around 10 for colors not at black) then the software is likely messing up color decoding.


As this applies to what you described, if you were to play the same type of video pattern in both programs they would report different on-screen RGB values. Of course if you were to play the same type of video pattern, you would want them to report the same RGB values. Being how that different operating systems, different connection types, different video driver versions, different playback software versions, and different settings can all react differently it's not a bad idea to just look at RGB values to determine what's going on with your exact software. Only if your software is doing either expanded or unexpanded levels are the HCFR patterns valid, and otherwise taking measurements from the actual playback software is the only way to get accurate measurements for what the software is actually doing.
 

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Quote:
Originally Posted by sotti /forum/post/14235498


The HCFR runs were done using the built-in GDI color feilds.

You can't use the built in fields for calibrating and then use DVD playback S/W.


The S/W player interacts/overrides with the video card driver differently than HCFR so everything from colour to gamma will be different.
 

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Discussion Starter #7

Quote:
Originally Posted by jvincent /forum/post/14239240


You can't use the built in fields for calibrating and then use DVD playback S/W.


The S/W player interacts/overrides with the video card driver differently than HCFR so everything from colour to gamma will be different.

Shouldn't the built-in feilds be most accurate for all input sources though? I mean if the one calibration is for the PC, satallite, wii, wouldn't those feilds provide the closest thing to what an actual signal generator would create.


Granted for specific calibration of the player software going from disc to display through the whole chain deffinetly is more accurate for that.
 

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Assuming that the built-in fields are capable of bypassing/controlling what the driver does, yes. But that's a huge assumption.


A proper signal generator will generate RGB (or YCbCr) values based on standards definitions. That is what the built-in patterns try to do. Unfortunately, and I have seen this first hand, the drivers tend to mess with that.


As a specific example I have calibrated my plasma, changed the drivers (leaving everything else the same, and then immediately remeasured. The results were significantly different.
 
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