HTPC, HDMI, RGB, YcBcR444 - argh!

Durzel · 14 Jul 2009 at 14:31

Looking for some input from people who have got media PCs wired directly up to their LCD/plasma televisions.

I've had a setup that seems to have been working for quite some time but I've never been absolutely sure that it's "correct". I've been led to believe there are some discs you can buy to calibrate your screen, is this true?

Basically I've just completely uninstalled my older Nvidia drivers and installed the latest ones which have reset my previous settings (which I forgot to make a note of)

I've got my media PC connected via DVI->HDMI to my Panasonic plasma. The default setting for the Nvidia drivers seems to be to output in RGB, but on the desktop it looks noticeably washed out - blacks look like dark greys, etc. When I load Vista Media Center (VMC) and play something it seems to correct itself a bit but in movies black still looks like dark grey.

If I set the colour output to YcBcR444 then the blacks go jet black both on the desktop and in movies, but I'm a bit worried that I'm losing definition - it almost seems too dark, if that makes sense.

Could anyone share what output they are using on their setups? (RGB or YCbCr444) together with any extra Nvidia control panel settings that would benefit me?

Thanks in advance.

V4NT0M · 14 Jul 2009 at 15:04

There shouldn't really be that much different and sRGB should be adequate really, have you tried messing with contrast, vibrance and from the sounds of it gamma settings?

wolvers · 14 Jul 2009 at 15:24

Durzel said:
I've got my media PC connected via DVI->HDMI to my Panasonic plasma. The default setting for the Nvidia drivers seems to be to output in RGB, but on the desktop it looks noticeably washed out - blacks look like dark greys, etc. When I load Vista Media Center (VMC) and play something it seems to correct itself a bit but in movies black still looks like dark grey.

In the Nvidia control panel select Nvidia to control colour settings and then in the advanced tap select 'full 0-255' in the drop down box. That should sort your blacks as greys problem.

I tend to leave all the other colour settings as they are in the Nvidia panel and set the colour controls on the display itself. In VMC there is a basic display set up option that will help you get the contrast, brightness and RGB levels somewhere near being right.

Durzel · 14 Jul 2009 at 15:37

Thanks will give that a crack.

Chris1712 · 14 Jul 2009 at 16:55

RBG levels and pc's are a real pain in the backside.

Basically

TV (and Film) use the 16-235 colourspace
PC uses 0-255

So if you watch a film in 0-255, the blacks and whites are getting completely washed out and most notably a lot of shadow detail is lost. Films/TV should be watched in 16-235 always. Unfortunately, a lot of tv's assume the 0-255 colourspace when a pc is plugged in. So you either need to tell the TV what colour space your using, or force you video decoder to do the other. The enhanced video renderer in Vista/7 uses the 16-235 colourspace so I would recommend using that, but you will have to delve into your tv's advanced menus to set it to the 'standard' rgb rather than 'enhanced'.

wolvers · 14 Jul 2009 at 19:36

Why does video in VMC look so bad when the NV panel is set to 16-235 then? I mean, like Durzel says, the blacks are grey and there's an obvious lack of vibrancy to the colours.

Chris1712 · 14 Jul 2009 at 23:08

Could be that the tv is set to 16-235, and so's the video which would reduce the range by another 16/20 again. Best way to check is to do a screengrab and use the colour picker in photoshop to see what values black is.

wolvers · 15 Jul 2009 at 10:17

What values am I looking for?

Chris1712 · 15 Jul 2009 at 12:25

Heres a quick example. You can see the black bars in both screens are extra black, because they are at RGB 0 (being rendered by the PC). The blacks in the first screen are also being rendered at RGB0, which is chopping the top and bottom off the picture range thus reducing shadow detail a lot.

The bottom shot, the video is in 16-235 but as its being played from pc the bars are still 0-255, and you can see the increase in shadow detail quite clearly.

EDIT: I think what you want to do, is either have everything set to 0-255 and tell the TV thats the case by setting HDMI to 'Enhanced' OR leave everything at 16-235 and have you TV on 'Standard'.

marscay · 15 Jul 2009 at 16:57

You could use the avs hd/mp4 calibration set so you can set your levels properly, to tell whether you're in 16-235 or 0-255 or something else

.

Available here - http://www.avsforum.com/avs-vb/showthread.php?t=948496

You want to run the file basicsettings.mp4 so that you can see flashing bars on rows 16-25 this will mean you're in 16-235 colorspace - it also enables you to set you're black levels/contrast correctly.

On my setup i run with a limited rgb (16-235) through CCC into my Onkyo and then into my set but it depends on what your signal your TV is set to or expects which will get you the 'correct' picture......when i set full range (0-255) i get the grey blacks because my set is expecting 16-235 and so blacks would start at 16 instead of 0.

You are best to stay in 16-235 when at all possible however for movies/tv, even if your TV can be set to full range RGB - limited RGB is preferrable.