Assetto Corsa + Oculus rift + Supersampling = jitters @ 90fps

[Cru Jones]

Looking for some help here, or just some knowledge. Here's what I'm experiencing..

Smooth performance with PPD at 1.0 and all graphic settings maxed.

As soon as I start to bump the PPD, the jitters start but framerate is maintained at 90fps.

By the time I reach about 1.8 PPD, the jitters are pretty harsh and only then do I see a framerate drop to about 45.

My main question is why am I seeing the jitters while maintaining 90fps?

The jitters by the way, seem to mostly happen during head movement, as I get the same amount of head movement jitters while in the pre-race menu.

Also, the amount of in game AA doesn't seem to affect the jitters, only the PPD seems to. I've tried setting the PPD in the debug tool as well as the oculus .cfg file and both produce the same results.

CPU - i5-6600k
GPU - GTX 1070

Thanks, Chris

[Mr Crisp]

Go to your Oculus install folder and go to the support folder and then diagnostics and run the Oculus Debug Tool and go to the Async Spacewarp dropdown and make sure its on and also turn the HUD to true so you can see what it happening.

At below 90fps, ASW will drop the framerate to 45fps and fill in the rest to match the displays 90hz and it should be smooth.

You can experiment with different settings, ASW disabled, enabled auto or locked on at 45fps etc to test. The HUD you can use to see what frametimes you are getting as well as what is happening to your framerate when dropping below 90fps.

You would really want ASW on auto so that if you can't make 90fps at all times minimum, then it will kick in and frames will always be smooth.

[NIKKI IXX]

Downsampling puts a heavy load on your gpu and is probably hitting your tracking latency by squeezing it's bandwidth or something like that.
How much experimenting have you done? The best overall experience is what you're after. No need in the rift to have all the eyecandy on and in particular reflections are a serious drag on performance. A GTX1070 will most likely start to choke if you bump PPD over 1.2 with mid/high game settings, but that 1.2 PPD is actually a significant improvement in image clarity. Start with a predetermined and modest PPD bump and back off game settings till the jitters are gone. And don't even try to maintain 90fps. Yes 90fps is like butter, But ASW 45fps and a clearer image is a better experience. Another trick that helps is to bump the AA in the ini. to 8x. (as you stated AA dont make a diff)(ask if you need instructions)
https://youtu.be/2empB-0abjc
No need to use the debug tool but to verify performance.

[rudski]

1,8 is nearly 4 times the load over 1.0.

Put the oculus in debug mode and select performance graph u will see if your system can
handle it

[Cru Jones]

Ok, thanks for the tips guys, I'll try them later and report back. Are the head tracking jitters from poor GPU performance or could that be a different problem?

[blue]

do you have post processing enabled .if so turn off as that effects fps and stutter a lot ..and then turn up your ppd a little more to maybe 1.4 if you have 1070

[NIKKI IXX]

clescell の投稿を引用：

Ok, thanks for the tips guys, I'll try them later and report back. Are the head tracking jitters from poor GPU performance or could that be a different problem?

My 1080 does the same thing at over 1.2 PPD and I've tried every conceivable combination of settings- if that helps. But I do use pp in order to get better skies and atmosphere, and I count on ASW to smooth it out. Seeing the fps at 45 was a little frustrating at first but I don't even check or monitor it anymore. Only a Titan V would fix this.
The rift switches pixels some 25 million times per second while tracking movement in under 15 milliseconds so just realize you are on the cutting edge like never before.

[Cru Jones]

If I'm keeping a constant 90 fps or 45+ with ASW, why am I getting the stutters at all? This is what I'm not understanding. When I have the performance HUD visible, the stutters happen when a compositor frame drops, but not my FPS. I've heard many things can cause CFDs, software, for example, but I'm not sure what to try.

My latest in game setting are all on high except for reflections which are at low with medium rendering frequency, PPE on because I like the way the car and sky looks, PPD at 1.0 and I still get some stuttering. If I turn PPE off, I'm sure the stutters would go away and I could even turn up the PPD a tad, but I'm still trying to understand why the stutters happen if my FPS is solid.

The image is still a bit soft too, and I assume it's because of the AA which I have to have on max to avoid the jaggie artifacts that really distract me.

I'm open to more things to try, let me know, thanks!