Scratching my head: OpenXR Motion Reprojection issue (RTX 3090/Ryzen 5600 x)

[falcon_120]

Hello everyone,

I've recently upgraded my GPU from a GTX 1080 TI, to a new EVGA RTX 3090 FTW3. Nothing else in my computer has changed.

Once changed, i've started the process of setting everything up to enjoy again DCS with the new card; updating drivers, installing evga software, updating DCS settings for the new card...

So once everything was ready i've started to test how smooth everything goes to be sure I'm where i want it to be, basically I am using 2 missions as tests bed, the F18 Hornet Caucasus free flight and the F16 Siria Free flight missions.

With these missions i get the following results: Caucasus F18 free flight i get a steady 90 FPS with my options, with the F16 Siria Free flight i get a mostly steady 60 FPS during the begining of the mission at low level near damascus? (the big city of the mission), and it goes up if i climb.

So everything is good and i decide to turn on Motion reprojection through the Openxr overlay in DCS, I set it to MR ON and unlocked. Everything else turned off (No FSR/NIS/CAS, tested with FFR in Quality/wide on and Off with similiar results) results:

-F16 Siria Free flight: At least during the beginning of the mission (not tested more than 2 min into the mission) everything is smooth as butter, steady 45 FPS; the DCS Fps counter shows 45 and sometimes 44 for a second, i can look into the town and everything seems smooth, also within the cockpit.

-F18 Caucasus free flight mission (also teste later with the A10 Siria free flight with same results): The motion reprojection does not work "well", instead of showing a constant 45 FPS, its showing something like 45,43,41,45,43,45,44,41, and the worst part is that when moving my head around the F18 cockpit the whole cockpit stutters. Its like when moving my head some frames are lost and i jump to a next frame. This is not the normal shimmering at the edges of the cockpit that you get with MR, but instead is like the whole cockpit jumps from one frame to the other when moving my head from left to right or right to left.

I'm scratching my head here, since i've been using Openxr MR for more than 1 year on my 1080 ti without this happening ever. If i turn off MR for that mission (F18 Caucasus free flight) i get steady 90 fps again. I'm a bit lost of what is causing this strange behavior.

Trying to solve the issue ive done the following:

-Turn off HPET

-Update Openxr TK to latest version

-download latest version of openComposite

-Reducing setting in DCS (No shadows, no MSAA, no AA, PD is always at 1.0 and 100% CRM in SteamVR and OXR TK, Ground textures to low)

-Put DCS.exe, OpenComposite priority to high (although not sure if i've done this alright, i should review it again)

I've seen that sometimes if i alt-tab or look into the task manager and jump in, the MR seems to "kick in" for some time and i get the steady 45 FPS with no cockpit jumps/stutter.

 

My system:

Ryzen 5600x, RTX 3090 FTW3 Ultra, ASUS ROG STRIX B550-F Gaming, 32 GB RAM Corsair vengance LPX DDR4, PSU Corsair HX1000

 

Any help is appreciated.

 

[Mars Exulte]

OXR MR has some flakey characteristics still and is generally inferior to other MR variants. Even when it's working perfectly, it has some artifacting, stutters, and general issues. There's supposed to be an improvement in the works though.

That said, have you tried locking it to 45? Sometimes MR can cause problems when it's going in and out of usage (which it may do if unlocked).

[falcon_120]

I have tried locking MR to 45, i've only tested it quickly since it appeared to suffer from the same issues, also i'm not too keen of locking it as i guess in MP in busy server i will need the 30 FPS motion reprojection. 

I will test it this afternoon in more detail to see if i get any benefit.

The thing that is puzzling me the most, is that MR has been working flawlessly on my system always, its been since i changed the GPU that i'm seeing this behavior. Just throwing some crazy ideas around, i know i've updated OpenComposite after changing the GPU and also Openxr Toolkit, maybe reverting to a previous version will do the trick...

Edited November 10, 2022 by falcon_120

[nikoel]

@edmuss

Mate, do you think that reprojection might not actually be "on" here

I have my doubts because reprojection *ALWAYS* = 90FPS

SteamVR can only do it at 45FPS - So it gives you one fake, followed by one real frame regardless if your graphics card is able to render 50FPS or 89FPS. So as soon as you can not keep the 45, you get instant satisfaction of going from 90FPS to <44FPS

Reason OpenXR is popular in with the crowd who are into the kink, is because unlike steamVR, it can keep you at 90FPS by stepping to 45, then 30, then 22 (then off). But those are not FPS, those are the number of real frames per the total 90 that you always get. You are always getting 90FPS

So at 45, FPS you get Real, Fake, Real, Fake, Real, Fake ninety times a second; at 30, you get Fake, Fake, Real, Fake, Fake Real, ninety times a second. and at 22 you get Fake, Fake, Fake, Real. Which is the VR equivalent of Duck Duck Goose

I preface with I don't know sh!t about f#ck when it comes repro, so care to chime in?

Edited November 10, 2022 by nikoel

[edmuss]

Your analogy is pretty close

It's odd that it works in one scenario but not in the other. Unless for some reason your GPU isn't pulling enough to keep the reprojection engaged but you should be able to easily.

Try resetting all of the openxr toolkit options, ensure that turbo mode is definitely off if you're using reprojection and have a play with locking and then unlocking the reprojection rate.

Turn on the developer performance overlay as well as the WMR one and keep an eye on postGPU frametimes as this is what displays some of the overheads caused by reprojection. If it's spiking to 8-9ms for example then that would likely manifest as a failure somewhere in the reprojection and it may simply be turning off. For reference, my 3080ti uses about 3-4ms overhead if I turn on reprojection.

[falcon_120]

I will! Where should I look to enable them? I guess the 1st one is from theOXR overlay in-game and the second one from Openxr for WMR app?

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[falcon_120]

So, It seems i have found something, it turns out that opening up ROG CPU-Z monitoring tool my CPU core speed is constantly changing speed between 3600Mhz and 4600 mhz, by alt tabbing in and out of the mission somehow i've managed to make my CPU stable in turbo mode (4,6ghz) and during some minutes i have a stable, stutter free Motion reprojection in the mission. 

SO it turns out that MR is working perfectly, is my CPU throttling back and forth the whole mission. For some reason my MB or CPU thinks that while gaming it does not need to go full speed, i need to find how to change that now...

EDIT: Not sure anyway if that is the problem as the same behavior happens with MR off but I get steady 90 fps, also i've read that is normal Precision boost override behavior in the Ryzen 5600x

Edited November 10, 2022 by falcon_120

[edmuss]

Turn off all software overclocking tools and set it up in hardware via bios

[falcon_120]

Turn off all software overclocking tools and set it up in hardware via bios

Just tried that, no improvement, definetely somethings is preventing Mr from kicking in in all its glory... :(

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[falcon_120]

12 hours ago, edmuss said:

Your analogy is pretty close

It's odd that it works in one scenario but not in the other. Unless for some reason your GPU isn't pulling enough to keep the reprojection engaged but you should be able to easily.

Try resetting all of the openxr toolkit options, ensure that turbo mode is definitely off if you're using reprojection and have a play with locking and then unlocking the reprojection rate.

Turn on the developer performance overlay as well as the WMR one and keep an eye on postGPU frametimes as this is what displays some of the overheads caused by reprojection. If it's spiking to 8-9ms for example then that would likely manifest as a failure somewhere in the reprojection and it may simply be turning off. For reference, my 3080ti uses about 3-4ms overhead if I turn on reprojection.

I've turned on both overlays and i've gather the following info for reference in caucasus with MR on:

Caucasus
JF17 free flight: Post CPU/GPU: 0,54/4ms AppGpu: 14 ms AppCPU: 9ms
F18 free flight: Post CPU/GPU: 0,54/3,2ms AppGpu: 11 ms AppCPU: 7,4ms
F16 free flight caucasus_ Post CPU/GPU: 0,54/4ms AppGpu: 16 ms AppCPU: 7ms

[sea2sky]

OpenXR is only good if you don't have to turn MR on. Otherwise - it sucks.

[edmuss]

That all looks about ok, I can't explain why the reprojection should be dropping out unless it's simply lags due to the CPU bouncing around.  It should hold a pretty steady boost clock unless you're thermal or power constrained?

[falcon_120]

That all looks about ok, I can't explain why the reprojection should be dropping out unless it's simply lags due to the CPU bouncing around.  It should hold a pretty steady boost clock unless you're thermal or power constrained?

Thanks!

I will just try to do some other system hygiene stuff (gpu drivers, maybe reinstalling OS, etc....). Thanks a lot for all the help.

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OpenXR is only good if you don't have to turn MR on. Otherwise - it sucks.

I wouldnt argue with you on that, but I've been a happy OXR MR user for several months with my 1080ti, and everything was really smooth. No strange cockpits spikes/stutters, just the normal Shimmering of wingtip and maybe the edge of the cockpit every now and then.

Maybe I will try to lower all the settings in DCS as I had it on that Gpu to see if that really makes any difference at all with MR

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[falcon_120]

Since I haven't been able to totally resolve this issue, sometimes is up and sometimes is not, I was wondering, is there any other motion reprojection runtime avaliable which I can try?

If I understand correctly using steamvr instead of OXR use the same MR, just not directly talking through the API but using a middle man for several calls right?
I've tested with SteamVR and I get similar results which is consistent with it.

Maybe there is a mod somewhere using oculus ASW for the reverb g2, one only can wish...

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[eatthis]

On 11/11/2022 at 12:33 AM, falcon_120 said:

I've turned on both overlays and i've gather the following info for reference in caucasus with MR on:

Caucasus
JF17 free flight: Post CPU/GPU: 0,54/4ms AppGpu: 14 ms AppCPU: 9ms
F18 free flight: Post CPU/GPU: 0,54/3,2ms AppGpu: 11 ms AppCPU: 7,4ms
F16 free flight caucasus_ Post CPU/GPU: 0,54/4ms AppGpu: 16 ms AppCPU: 7ms

how do you get the post cpu and what does it mean?