Nvidia card losing 0-255 output?

[webminster]

Have been wrestling a new intermittent issue with new TV (LG 65EF9500 OLED). Have configured the TV to PC input on HDM1, and configured my GTX750 card to RGB full output 8bpc. It works OK....

Except I've had a couple of situations since where the picture goes gray. Checking the black clipping patterns playing back in WMC7 show the picture has changed from the 17+ bars blinking to almost all the bars blinking.

I've checked the following:
* Have NpminalRange registry entry set to 2 (limited).
* Switching TV off then on doesn't change it back.
* Restarting the WMC shell doesn't change it back.
* What /does/ help is closing WMC, going to Nvidia control panel, and toggling the output level from full to limited, and back. Restarting WMC after that shows the correct levels.

As far as the control panel is showing, it still shows the 'full' output level while the problem is happening. I'm experimenting with changing the NominalRange to "1" but haven't rebooted the system yet (still looks same after just a WMC restart). Also experimenting with overriding the video settings on nvidia control panel to nvidia settings, 16-235 levels.

Currently using Nvidia driver version 355.98.

Has anyone who's set PC output levels had problems like this? Thanks in advance.

[crawfish]

Based on your Black Clipping results, it sounds like for some reason, the TV is switching from Video Levels to PC Levels, which changes its black level from 16 to 0, causing the lower-numbered bars to appear at its current Brightness setting. If the TV's dynamic range option on that input is set to "Auto", try setting it to whatever it calls Video Levels. My Panasonic plasma calls it "Standard (16-235)".

So I'm clear, you have the Nvidia Control Panel set up as follows (which is how I do it for my TV):

1. Change Resolution: Output color depth = 8 bpc, Output dynamic range = Full.
2. Everything under the Video node at defaults.
3. You didn't mention this, but I set "Content type reported to the display" to "Full-screen videos" in "Adjust Desktop Color Settings". Might be worth a try before fooling with anything else.

This means the card is outputting RGB 0-255, while video players are choosing to output Video Levels or PC Levels. WMC outputs Video Levels by default. The TV also needs to be set for Video Levels for WMC video to look correct. Note this is the ideal passthrough configuration for video, but it does create a levels mismatch for the desktop and WMC UI. Fortunately, it doesn't interfere with their usage, and it's not a problem if you just watch video and don't do any color-critical desktop work.

You don't need to change anything in (2) to experiment with WMC outputting PC Levels. Leave (2) at defaults, change NominalRange to 1, and reboot. You will also need to ensure your TV is set to PC Levels.

[webminster]

Thanks for the fast reply! Yes, everythin was at the defaults in video, the "use application defaults" settings. Also, yes, "full screen videos" is set, I can't live without that....

As far as the TV switching levels - the input was set to, and claims to be set to, PC level. Switching the TV off and on didn't change anything (it did say "PC" when the screen showed the input banner on start). Also, going to TV input settings and toggling the HDMI1 input from PC settings to HDMI, then back, didn't change anything either. Only the toggling of the video card output level reset stuff back to working again.

Do you find you need to set NominalRange in the registry, or do you have success with omitting the registry entry with recent drivers, and with application-defaults in the Control Panel settings? If you do, which NominalRange setting are you using?

[crawfish]

As far as the TV switching levels - the input was set to, and claims to be set to, PC level. Switching the TV off and on didn't change anything (it did say "PC" when the screen showed the input banner on start). Also, going to TV input settings and toggling the HDMI1 input from PC settings to HDMI, then back, didn't change anything either. Only the toggling of the video card output level reset stuff back to working again.

If your TV really is expecting PC Levels, setting NominalRange to 1 should fix it up. The value 2 you were using is wrong in that case, but even so, I don't know why it wouldn't be consistently wrong.

Do you find you need to set NominalRange in the registry, or do you have success with omitting the registry entry with recent drivers, and with application-defaults in the Control Panel settings? If you do, which NominalRange setting are you using?

I've never had to create a NominalRange value in the registry to use the configuration I described with my GT430 or my current GT640, but my setup is different than yours. I misunderstood what you were trying to do, which if I now understand correctly, is for video players on your PC to output PC Levels. That follows from setting your TV to PC Levels, and for that to work for WMC, you need to set NominalRange to 1. That's a valid configuration if you want levels consistency between desktop and video, but the Video Levels expansion does sacrifice BTB and WTW, and when I tried it, I found I had to adjust Brightness in the NVCP to get bar 17 and maybe 18 flashing on my TV. OTOH, for the video passthrough configuration I use, I can make all adjustments on the TV, and the PC video output is consistent with my BD player and other video devices.

You could also delete NominalRange and set the dynamic range in NVCP's "Adjust Video Color Settings" page. WMC will respect it, but I don't recommend it due to the problem I described here (which may or may not still be an issue):

http://forum.kodi.tv/showthread.php?tid=180884

I like to leave this section as "With the video player settings" when possible.

[webminster]

I really don't want to have the video players output PC levels. What I'm finding on this TV is that motion artifacts are least annoying using the HDMI input as PC. Attempts to fix artifacts while on normal HDMI input configuration (turning off or altering TruMotion, etc) just don't seem as smooth as using the input set as PC.

The computer is 100% WMC use. So the basis is TV at PC levels, and whatever else I have to do to get proper WMC video output to a TV set at PC levels. /And/ stay.

[crawfish]

Setting NominalRange to 1 should fix it up. If that isn't stable, delete it and try setting NVCP's "Adjust Video Color Settings / Dynamic Range" to "Full (0-255)". If that isn't stable, I dunno. I've never known levels to change by themselves.

[webminster]

OK... so seemingly fixing the Dynamic Range under Video Color to 16-235 didn't stabilize things.
Interesting, from a quick test rebooting between and then looking at black clipping pattern in WMC, I see no obvious difference between HKEY_LOCAL_MACHINE\SOFTWARE\Debug\ehPresenter.dll\NominalRange set to dword 1 or 2. Both show the same bars (in my case 17+ flashing).
One slightly odd thing is it looks like something "recalibrates" starting the black clipping pattern - like i see lower bars flash, but it quickly "resets" to showing what I expect. I don't know if this TV supposedly "auto-senses" levels (so to speak) and guesses wrong occasionally... never heard of such a thing.

[crawfish]

OK... so seemingly fixing the Dynamic Range under Video Color to 16-235 didn't stabilize things.

If your TV is expecting PC Levels as I thought was established, then you would need to set the Video Dynamic Range to "Full (0-255)" and delete NominalRange. However, I would want to leave the Color Adjustments as "With the video player settings" and try using NominalRange set to 1.

Interesting, from a quick test rebooting between and then looking at black clipping pattern in WMC, I see no obvious difference between HKEY_LOCAL_MACHINE\SOFTWARE\Debug\ehPresenter.dll\NominalRange set to dword 1 or 2. Both show the same bars (in my case 17+ flashing).

Did you revert the NVCP to "With the video player settings"?

With the TV set to PC Levels and Brightness set appropriately, I would expect NominalRange = 1 to look fine and 2 to show bars below 17. You can try the following to see if NominalRange is behaving as expected. With it set to 1 (PC Levels), you should not observe any bars below 17 as you increase Brightness on the TV, because they were lost in the expansion from Video to PC Levels. With it set to 2, the bars should appear as you increase Brightness, and if they do, I don't understand why there weren't already showing given that your TV is set to PC Levels. If they don't appear as you increase Brightness, then something is wrong.

One slightly odd thing is it looks like something "recalibrates" starting the black clipping pattern - like i see lower bars flash, but it quickly "resets" to showing what I expect. I don't know if this TV supposedly "auto-senses" levels (so to speak) and guesses wrong occasionally... never heard of such a thing.

I've never seen that either. I'm sure avsforum.com has a thread dedicated to your TV. Maybe someone with the same set can help.

[webminster]

Have experimented with setting NominalRange=1, and "with video player settings". This created a "mess".. the TV black levels went to a point I had to crank the brightness way way up (like to 75 at least from my original 54), and crank contrast way way down. End result was a badly gray washed out picture. However, yes, cranking up the brightness did give be bars, never anything below 17.

Stuff is recording, so can't experiment now with NR=2.

And, yeah, have been on AVSforum, nothing yet.

[webminster]

I can't find a specific setting on the TV for dynamic range, as you mentioned. There is the setting on the input selector, that sets the type of input (bluray, PC, STB)... consensus on the AVSforum is that setting this to PC makes the level change. But at this point I'm just not so sure.

All else there is on this I can find is the black level (low, high, auto), which I didn't figure was it.

[stuartm]

IIRC On LG TV's Black level High = 0-255 and black level Low = 16-235 dont know what Auto might mean, perhaps then it does try some auto selection. This is from my notes as I don't currently have an LG TV.

[webminster]

Thanks, I may try throwing that into all the testing iterations... Not sure why LG has a "PC" setting for the input, but would have a separate setting for levels. I have it at the defaul "Low" now, never have set it to auto.

[crawfish]

Thanks, I may try throwing that into all the testing iterations... Not sure why LG has a "PC" setting for the input, but would have a separate setting for levels. I have it at the defaul "Low" now, never have set it to auto.

OK, so if "Low" is 16-235 as stuartm says, your TV is expecting Video Levels, and we're back to what I thought you were using and what I use, which I described in my first message. Maybe it's getting confused by using "Low" for the "PC" input, which could be considered somewhat unusual.

[webminster]

Another question, if I may... If I were to set the NominalRange=1, and full range GPU output, which brightness/contrast comes into play? When I experimented with that before, if made a rather mess out of the TV settings, as above, really threw off the TV black levels. If one does this, leaving the NVCP video settings at "application", would you try to hack the TV controls, or use WMC's TV setup to try to set brightness/contrast?

[crawfish]

Another question, if I may... If I were to set the NominalRange=1, and full range GPU output, which brightness/contrast comes into play? When I experimented with that before, if made a rather mess out of the TV settings, as above, really threw off the TV black levels.

NominalRange = 1 means WMC outputs PC Levels, so your TV needs to be set to PC Levels, so they will agree that black is RGB 0. The TV's Brightness setting should then be more or less correct at whatever its default value is.

If one does this, leaving the NVCP video settings at "application", would you try to hack the TV controls, or use WMC's TV setup to try to set brightness/contrast?

I would make all adjustments on the TV using the AVS HD 709 patterns. The numbered bars are far more precise than WMC's yuppies, and WMC's Contrast pattern is downright wrong due to all the WTW content it contains; that is, it will look fairly blown out unless you've set Contrast so that a lot of WTW can be displayed, which is not really necessary, and, of course, WTW cannot be displayed at all when using PC Levels for reasons given earlier.

[webminster]

Just following back up on all this... never have been able to find a mode where I can get the TV to consistently power up in 0-255. Much of the time it comes up fine... and occasionally powers up all grey. Need a power cycle on the TV to get it to display proper dark levels. At a loss. The alternative is forget 0-255, but then I wind up with motion issues I can't get past.

[webminster]

I never closed this out, just for posterity... Issue appears to be the LG 65EF9500. Found others with same issue, losing track of black levels on power-on. Only known solution to date is run in YCbCr mode (otherwise you need to power cycle the TV when you see the pale screen).

[crawfish]

I never closed this out, just for posterity... Issue appears to be the LG 65EF9500. Found others with same issue, losing track of black levels on power-on. Only known solution to date is run in YCbCr mode (otherwise you need to power cycle the TV when you see the pale screen).

That sucks. See these messages for what outputting YCbCr from a PC implies:

http://www.thegreenbutton.tv/forums/vie ... 971#p82971
http://www.thegreenbutton.tv/forums/vie ... 995#p82995

[webminster]

Yeah... but to my eyes at least less an issue than the WAF and anger caused by LG's bad firmware.

[crawfish]

Yeah... but to my eyes at least less an issue than the WAF and anger caused by LG's bad firmware.

I'd do the same thing under the circumstances. LG has me SMH at a problem like this with their flagship OLED.