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G-SYNC/FreeSync

Started by Sliver X, December 22, 2019, 01:08:34 PM

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Sliver X

I bought a relatively cheap 27" monitor last year. I mainly got it due to its 144Hz refresh rate and 2ms response time; it also advertised support for FreeSync but since I haven't bought an AMD GPU since they were still ATI it didn't even register as an afterthought. Until last week.

I ran across the release notes for nVidia 417.71 when manually grabbing a newer driver for my GPU than what this distro I run's repositories have. One line in particular stood out:

G-SYNC Compatible Support

G-SYNC was released a hell of a lot earlier than v417.71, so that struck me as odd. I looked into it and found it means nVidia GPUs can now do variable refresh rates with FreeSync capable monitors (With several caveats, of course).

So I did a manual install of nVidia 430.50 and enabled FreeSync in my monitor's OSD. At first I couldn't find any way to set G-SYNC, then realized I'd forgotten one of the aforementioned caveats is that it only works over Display Port, not HDMI.

Connecting it via Display Port made a new option appear in the nvidia-settings console (X Server Display Configuration > Advanced): "Allow G-SYNC on monitor not validated as G-SYNC Compatible". I enabled this, manually set the resolution and refresh rate the the maximum the monitor supports and also made a few changes under the "OpenGL Settings" menu: Unchecked "Sync to VBlank" and checked "Allow Flipping", "Allow G-SYNC/G-SYNC Compatible" and "Enable G-SYNC-G-SYNC Compatible Visual Indicator".

The last one will overlay text on the upper right part of the screen showing if G-SYNC is actually running or not, which helped at first.



I tested initially on some FPS games (Quake II under the KMQuake2 engine, The Outer Worlds and Skyrim)... I've been playing FPS games since 1996 and have never had motion sickness from it. Until now. So long as I was hitting 144FPS the motion was uncannily smooth, as if I were actually moving my head around in the game's space. It took a bit to get used to, but now that I have I really don't want to ever use a fixed rate display again.

My second test was with emulation. Despite enabling G-SYNC, Mednafen's scrolling was still oddly choppy with mild tearing at times. So I bit the bullet and downloaded Retroarch (The build from Ubuntu Xenial works fine if you're on Debian Stretch, like me). Just like nvidia-settings, there are a few things that need enabled to make it work on its end:

Config > Video > Video Driver To Use > gl1
Config > Video > Start In Fullscreen Mode
Config > Video > Output > Set Display-Reported Refresh Rate (This should be very close to the highest refresh rate your monitor can support. If it isn't, check nvidia-settings!)
Config > Frame Throttle > Sync To Exact Content Refresh Rate

I initially tried Super Mario Bros. via the NEStopia core. Scrolling was absolutely perfect, just like it was on a CRT. Again, the motion seemed unnaturally smooth after decades of using emulators.

But that's kind of subjective even though I could tell a difference. Next I tried some games that had rendering problems due to refresh rate mismatches...

Bio Metal (SNES): The first stage has fast scrolling background layers with transparencies. Typically the movement is very choppy, even with traditional v-sync enabled. Scrolling is virtually perfect with G-SYNC, with no detectable stuttering or tearing.

Belmont's Revenge (Gameboy / Gameboy Color): The beginning of the Cloud Castle level has a flickering effect on the mountains outside the windows that displays various artifacts on most emulators: They flicker as they should with G-SYNC.

Overall, I'm fairly impressed with this, and the fact that it can be done on FreeSync displays instead of only (ridiculously overpriced) G-SYNC monitors is great.

If you have all the bits needed for using this, I highly recommend at least giving it a try. You may be surprised.


FAST6191

"but now that I have I really don't want to ever use a fixed rate display again."
Fixed rate or just not LCD 60Hz and lower?

Anyway I have never been overly impressed with high frame rate content, indeed I think I would rather have 4K than that and such things are mostly only any use if I am being a sniper in a game that can do the distance, playing a RTS that foolishly allows such a view size or doing something productive with video, CAD or spreadsheets.

Sliver X

QuoteFixed rate or just not LCD 60Hz and lower?

"Fixed Rate" as in exactly what it sounds like: The refresh rate is the same during the entire time you're doing whatever it is you're doing. The essence of G-SYNC/FreeSync is that the refresh rate *changes* (VRR) to match the GPU's output, and it can hit values between integers like 60Hz, 75Hz, etc.

QuoteAnyway I have never been overly impressed with high frame rate content, indeed I think I would rather have 4K than that and such things are mostly only any use if I am being a sniper in a game that can do the distance, playing a RTS that foolishly allows such a view size or doing something productive with video, CAD or spreadsheets.

That's great, but this doesn't really have all that much to do with high frame rates, rather variable refresh rates (You could have a FreeSync monitor with a max of 10Hz and it would still work, just not, you know, above 10Hz). And you could get a 4K display that supports VRR too, if that's your thing.

And how exactly were my examples of emulating 2D consoles related to your last three examples? As far as the latter goes, I can now move spreadsheets or any CAD/whatever windows around my desktop with absolutely no tearing now too.

I also forgot to mention that this also has an effect of decreasing input lag from controller presses in games, though it's fairly subtle.

FAST6191

Quote from: Sliver X on December 22, 2019, 01:52:03 PM
"Fixed Rate" as in exactly what it sounds like: The refresh rate is the same during the entire time you're doing whatever it is you're doing. The essence of G-SYNC/FreeSync is that the refresh rate *changes* (VRR) to match the GPU's output, and it can hit values between integers like 60Hz, 75Hz, etc.

That's great, but this doesn't really have all that much to do with high frame rates, rather variable refresh rates (You could have a FreeSync monitor with a max of 10Hz and it would still work, just not, you know, above 10Hz). And you could get a 4K display that supports VRR too, if that's your thing.

And how exactly were my examples of emulating 2D consoles related to your last three examples? As far as the latter goes, I can now move spreadsheets or any CAD/whatever windows around my desktop with absolutely no tearing now too.

I also forgot to mention that this also has an effect of decreasing input lag from controller presses in games, though it's fairly subtle.

I got what was being discussed. I just saw three possibilities (variable frame rate is worth the effort, sticking with LCD refreshes* then greater than 60Hz, possibly considerably so, is where it is at but still fixed rate in the end, or 60Hz is all that people really need and anything more is so much nonsense like we see with audiophiles buying fancy cables that do nothing) where you condensed the VFR and high refresh rate into one possibility.

*going back to CRT then higher refresh rates there have tangible results that most people can see or be easily trained to see. They have good reasons for that though.

I was saying 4K is perhaps not a chocolate teapot (even if I did have to go outside games to get more than a handful of examples) but even as dubious as its uses/merits are it was still more than I am likely to find greater than 60Hz, or indeed variable rates, amount to.

As far as input lag then I thought most PC games decoupled input from draw years ago and for consoles I have never been especially bothered, though I tend to use ps/2 keyboards so I am probably less likely than most to be bothered. To say nothing of again it could just be that you were playing it at what is effectively a higher frame rate and all that such things are said to imply.

tc

Consoles have historically been refresh rate locked. Other than 60Hz (NTSC) or 50Hz (PAL) selection.

Xbox One introduced VRR, but in practice very few games have uncapped framerates and consistently exceed 60 frames per second.

Spooniest

I'm curious about how I would even find what refresh rates my monitor supports. I did read the manual for it, but it seems like it was written in Korean, translated to Japanese, fed through a cotton gin, reassembled and then translated to English.

Is there a way to do this with just my hardware/software?

Also, what's a Display Port?
Yamero~~!

Sliver X

Windows:

Hit WIN+R and type this in the run dialog: control.exe desk.cpl,Settings,@Settings

Select "Advanced Settings", then select "Show All Modes" on the window that popped up.

Linux:

Type xrandr in a terminal.

DisplayPort is the bus/connector that's to replace DVI and VGA.

Spooniest

Quote from: Sliver X on December 22, 2019, 08:53:32 PM
Windows:

Hit WIN+R and type this in the run dialog: control.exe desk.cpl,Settings,@Settings

Select "Advanced Settings", then select "Show All Modes" on the window that popped up.

I found it, thank you. There were a couple more steps, though. What you call "advanced settings" is actually labelled "advanced display settings," and then it is also necessary to click on "display adapter properties for display 1," then the "List all modes" button is in the popup window.

Also, I think my integrated card has one of those, but the dedicated GPU I'm using doesn't have one. Guess I'm out of luck on this one.
Yamero~~!

Starscream

You can try custom modes and see how low/high it goes. It's relatively easy with Nividia, I found out my monitor can do 50 Hz despite the manual stating the limit is 56.