ViewPortOut instead of Overscan comp. I need help!

[C-J]

My distro (PCLOS) upgraded to 302.17, and found Overscan Compensation no longer available; having to use ViewPortOut in MetaModes instead.

I am having no luck trying to implement it, so if someone could set me on the right path, I would appreciate it.

Geforce GTS 250EN -> Samsung LCD 1280x720
GPU-0 -> DFP-1
Overscan = 80 (in prior versions)

My line in xorg.conf, Screen section:

Option "metamodes" "DFP-1: 1280x720 { ViewPortOut=1280x720+20+20 }"

(I do not know if +20+20 is the right figure for me, I have tried different figures.)

... then reboot. This has no effect at all.

I have also tried setting it 'directly' with:

nvidia-settings --assign 0/CurrentMetaMode="DFP-0: 1280x720 { ViewPortOut=1280x720+20+20 }"

No effect whatever.

If someone could point out what I am doing wrong, it might save me a few hairs.

Cheers!
CJ

[AaronP]

Your configuration of "1280x720 { ViewPortOut=1280x720+20+20 }" doesn't make sense because the bottom 20 lines and rightmost 20 columns would extend outside the physical 1280x720 region of the screen. Check /var/log/Xorg.0.log for errors. For example, on my system if I try something similar, I get this:

[  2557.636] (WW) NVIDIA(0): custom viewPortOut, 1920 x 1200 +20 +20, does not fit within
[  2557.636] (WW) NVIDIA(0):     rasterSize, 1920x1200; ignoring custom viewPortOut
[  2557.673] (II) NVIDIA(0): Setting mode "GPU-0.DP-2:1920x1200{ViewPortOut=1920x1200+20+20}"

To get, e.g., 20 pixels of border around the whole image, shrink the dimensions by 40:

nvidia-settings --assign 0/CurrentMetaMode="DFP-0: 1280x720 { ViewPortOut=1240x680+20+20 }"

This will shrink your desktop to 1240x680 and center it within the physical screen.

If you want to achieve the scaling that the old overscan compensation slider used, you can specify ViewPortIn as well:

nvidia-settings --assign 0/CurrentMetaMode="DFP-0: 1280x720 { ViewPortOut=1240x680+20+20, ViewPortIn=1280x720 }"

[C-J]

I was beginning to suspect that - and my tired eyes did not notice the different figures in README, so thank you for putting me straight.

Can you just confirm the probably-obvious:

The first method (on my system):

nvidia-settings --assign 0/CurrentMetaMode="DFP-1: 1280x720 { ViewPortOut=1206x672+37+24 }"

... is pixel-perfect,

while the second one:

nvidia-settings --assign 0/CurrentMetaMode="DFP-1: 1280x720 { ViewPortOut=1206x672+37+24, ViewPortIn=1280x720 }"

... is 'squeezed', i.e. is not pixel-perfect.

In other words, I am choosing between a smaller, sharp display - contra - bigger, blurry display, pixel-wise?

Cheers!
CJ

[AaronP]

Originally Posted by C-J

In other words, I am choosing between a smaller, sharp display - contra - bigger, blurry display, pixel-wise?

Right. In theory, the "pixel-perfect" configuration is better because you won't get the blurring that occurs with scaling. However, some applications might have trouble with such a configuration. For example, another poster complained in a different thread that MythTV (IIRC) only works correctly when the desktop is actually 1920x1080, and that chopping off parts of it for overscan compensation causes some sort of really slow UI resize operation that results in worse blurring than GPU scaling does. I'd consider that a bug in the application, but a scaling configuration is an easy way to work around it.

I guess the moral of the story is that which method you use depends on what you want to do with it, but you at least have the choice now.

[C-J]

Yes, I did come across the thread with Myth-TV; though this is for a simple internet/movie-watching PC, so I opted for sharpness; so far I have had no adverse effect (bar a shorcut on the Desktop that all of a sudden is nowhere visible but still in the Desktop folder, but alas, that's a small matter).

I appreciate you taking the time to explain this to me, and helping me out in the first place. Thank you kindly!

I have another issue with a dual screen setup, but I shall start another thread for this.

Cheers!
CJ

[C-J]

Originally Posted by C-J

so far I have had no adverse effects

Just for the record: without scaling, youtube fullscreen is confused and loses borders; to avoid this, scaling seems the only way.

Cheers!
CJ