Kind of confused ... VRR (now) working?

[Wordsmith9091]

Like a lot of people, I went down the rabbit hole of trying to get a good living room 4K120 streaming experience — eventually buying a UM760 mini-PC and putting Bazzite on it (with 4:2:0 output from the HDMI port in Linux, because the HDMI Forum can go f--- itself, but whatever).

And then I realized that if my games wouldn't get a consistent 4K120HZ after overhead for the streaming, it wouldn't help me much anyway. So I tooled around with VRR in Moonlight but found what others before me had — I could get my VRR/Freesync/GSync compatable-capable display to report varying framerates with VRR enabled in the OS (or in this case, Gamescope) settings, but the game still felt choppy. But the framerates didn't seem to quite sync up with those reported by software monitoring, and if I'm not mistaken, @ClassicOldSong, I've seen you say elsewhere it really can't work for Moonlight-style streaming.

I know some people have reported VRR working under Windows if they force the Vulkan renderer, but most of what I've seen suggests mixed-bag results there, too.

And then I tried again last night after updating my Nvidia drivers to the most recent versions (the ones that, incidentally, also now allow Smooth Motion on 4xxx) ... and things seem really smooth even as my framerates fluctuate between about 80 and 105 throughout gameplay. I've been playing Horizon Forbidden West, and doing my usual test for smooth streaming — I'll pan the camera around the character and look for any stutters or hiccups. Things just look ... good.

(Incidentally, turning on smooth motion for this game doesn't seem to do anything, but I'm not sure if it's that it's not doing anything on the host or that the generated frames aren't being captured in the stream. I haven't tried it locally. Using DLSS or FSR framegen in the game while streaming I get a mixed experience and I've generally left it off.)

@ClassicOldSong - Any idea why this suddenly seems to be working well? Do you know of anything in the newest Nvidia drivers that would change how the video is encoded or streamed via Apollo, that would allow for VRR? Or is this possibly not actually VRR I'm seeing, but a recent framepacing improvement on your part?

[ClassicOldSong]

VRR is still not meaningful through streams

You need to isolate the variable here: does updating the driver alone made things better, or have you upgraded both the driver and Apollo? Both could make a difference to the result, but they don't make any difference to my setup though, it's always smooth.

Actually with 120hz you shouldn't be able to tell the difference between few unaligned frames from VRR, maybe it's the new frame pacing solved unaligned frame capturing issues?

[Wordsmith9091]

I was pretty sure all I'd changed since the last time I tried was the driver, but I'll need to more carefully test one element at a time when I get a chance. I'm still on .4.6.

I've always gotten smooth results when the game (without using any framegen) could match either my client device's refresh rate or could be capped at clean divisor of it, but I definitely (until now) felt the stutters when I had the client and stream at 120hz (or a fractional refresh like 118.8 or 119.88) and a game somewhere underneath it, whether it's around 80-90fps or even very close to the refresh rate, like 110-115. I could see it most when panning the "camera," though I felt it less during action. This definitely seems different (and better), whichever is the cause.

I've never had good results with DLSS or FSR framegen over the stream, though. Sometimes it seems to look smoother in moments, and more jittery in others. LS on the host seems to do a good job and translate well to the stream, but the performance hit to the base framerate is significant enough (especially with the overhead from the stream) that I don't usually use it. And, of course, it shows more artifacts than DLSS or FSR framegen, but that's to be expected.

[Wordsmith9091]

OK, this seems notable. Using my Macbook Pro as a client, on either the internal display or on an external display with VRR disabled, I don't see this improvement. Camera pans still show little jitters for a ~100fps scene on a 120Hz fixed display, with a 4K120Hz stream in H.265. It's far from unplayable, but they're there.

On the same Macbook, if I enable VRR for the external display, I DO see this improvement. The camera pans look fluid, nearly as good as running natively on the host with VRR.

I really don't understand what I'm seeing and believe that you know more than I do when you say VRR shouldn't be a factor ... but something's having an effect here.

Note that so far I've only been testing any of these scenarios with the "double refresh rate" option enabled, H.265. I'll keep playing around.

[Wordsmith9091]

I'm curious what you wind up seeing in games. The situation I'm talking about is specifically one where the stream is set to 120fps (4K120 in my case) and the client is at 120hz (or rather, a 120hz max with VRR enabled, which on my LG C1 actually maxes out as ~118.80), but the content/game is somewhere under 120fps. In my case, that's been Horizon Forbidden West varying around 80-110fps, depending on the scene. Until recently, VRR made no difference for me, but I could get very smooth gameplay capping my frames at 60fps and setting the client accordingly.

With games where my GPU could reliably render 4K120, capping at 120 also got me smooth gameplay. It's only the sub-120fps-on-120-fps/hz stream situation where I could previously see stutters that now seem to vanish with VRR.

I haven't had time to play/test further myself since we started talking on this thread, though, and it looks like there's been one more nvidia driver update since then, too.

[ClassicOldSong]

Well it does get smoother, but I think it's a macOS only thing...

Tested with Cyberpunk 2077, rendering at ~80fps on my 4080S in 4K

I started the same stream on my Android device which doesn't have VRR, set both devices to 120hz, macOS is only as smooth as the android device when VRR is on, not that smooth when it's off.

My monitor supports 40-120hz VRR, and 144hz in non-VRR mode, but selecting 144hz with a 120hz stream playing at ~80fps feels like VRR is enabled.

[Wordsmith9091]

I first observed this on my Bazzite box (a Minisforum UM760 Slim mini-PC connected over HDMI), connected to an LG C1 in my living room, before seeing it on MacOS. I only tried on MacOS to see if I could repeat it on a second client.

On the Mac, I didn't see any improvement on the internal screen with promotion enabled, but I DID when connected to my usual desktop monitor with VRR (with a 48-240hz range, I think).

But I'm 95% that when I tried the same thing on the Bazzite box a few weeks ago, I didn't see any improvement at all from enabling VRR. That's what makes me wonder if it may be related to the newer Nvidia drivers on the host machine (win 11, 9950x3d, 4080S), since I'm not sure of anything else that changed in the interim. I wasn't really methodically testing for it, so I wasn't isolating one thing at a time and trying it -- I had just tried it again for the first time in a while and saw the improvement.

I will note that if I can match the client maximum refresh/stream fps/game fps exactly, it's still a little bit smoother feeling than even this "maybe-VRR" experience I'm talking about. But the "maybe VRR" is definitely markedly smoother than with VRR disabled, and definitely smoother than it was when I tried to use VRR weeks ago.

[ClassicOldSong]

One thing to mention, I have Nvidia Reflex on, which essentially is a fps limiter

[Wordsmith9091]

I've tried with Reflex both on and off, in the in-game settings for this particular game. It always seems to me like it's slightly smoother off while streaming, but that may be a placebo effect.

(And that observation predates whatever is going on with enabling VRR having an effect)