Motion smoothing not working with RTX 4070 and valve index?

[nothingtofear]

ISSUE
I swapped my GPU to an RTX 4070 from a GTX 1070 ti this week and noticed that motion smoothing is no longer working on my system. This applies to both the SteamVR beta and the main branch.

OS
Windows 10

OTHER SYSTEM INFORMATION
CPU is Ryzen 3700x
HMD is valve index headset and controllers

STEPS
1. Go to SteamVR video settings while an application is running.
2. Change the motion smoothing setting in the per application video settings for any currently running application to force always on.

RESULT
The application runs at half the headset refresh rate but the reprojected frames are not adjusted to account for movement of the headset or the scene. This can be seen as a double image for any translational motion like interleaved reprojection.

EXPECTED
The application runs at half the headset refresh rate and the reprojected frames account for movement so there is no double image seen on moving objects.

[CptLucky8]

+1

Index + SteamVR 1.27.5 (latest) + NVidia 536.99

Swapped a 2070S for a 4070 and motion smoothing doesn't seem to work anymore, at least in FS2020. I can clearly see juddering, regardless of GPU workload (lowering all game settings for ex.).

It might seem there is a little bit less juddering with motion smoothing enabled vs disabled, but if it is, it looks more like it is doing half the work for motion smoothing, as if it is re-projecting pixels half the distance only.

It is definitely not the level of smoothing I used to have with the 2070S and earlier SteamVR version (IIRC last time I tried was probably with 1.26.xxx).

FWIW: same hardware but G2 + WMR with FS2020 and motion smoothing works.

[CptLucky8]

Additional information: I've just tested with HLA, and the only setting which shows less juddering is "ENABLE" and "AUTO". When choosing "ALWAYS ON" or any manual fixed rate, it will render as if there is no motion smoothing.

Please note even in ENABLE + AUTO, it is not "as smooth" as it used to be and it still shows some juddering. I believe this might be due to "AUTO" which is switching between 2 rates constantly though, effectively rendering with motion smoothing for a 1 or 2 frames, then no motion smoothing for the next 1, then motion smoothing again, etc...

Being able to "lock" the rate is paramount to stable motion smoothing and I wish Steam will fix this in the next updates!

[CptLucky8]

Additional information: I've managed to downgrade SteamVR to 1.26.7 and test HLA, unfortunately the problem persists.

To recap:

- Motion Smoothing Enabled + Auto = smoother but some juddering still
- Motion Smoothing Enabled + Fixed Rate (any rate, any prediction) = juddering
- Motion Smoothing Always ON + Auto = juddering
- Motion Smoothing Always ON + Fixed Rate (any rate, any prediction) = juddering
- Doesn't seem to depend on HMD Hz (Index tested 80,90,120,144)
- Doesn't seem to depend on GPU load either (tested with lowest settings with FS2020).

At this stage, I can only assume some possible causes, for example:

- There is a bug with the 4070 and OpticalFlow SDK / NVEnc.
- SteamVR code in latest revisions which broke motion smoothing (I'm noticing a new "dashboard" setting, "steamMatchesHMDFramerate" introduced with 1.27.5 ?!)
- Latest(s) NVidia driver changed their APIs and/or API usage, and SteamVR fails to use the new APIs properly (like NVEnc if used as backup for computing the motion vectors, or Optical Flow SDK changes?)
- Something else!

I hope this helps and I'll be glad to further assist in resolving this issue.

[CptLucky8]

For infos, Motion Smoothing is still not working with SteamVR v2.0.2 and Valve Index.

Tested with Index, SteamVR v2.0.2, RTX 4070, NVidia 536.99

Like described above, there is some motion smoothing kicking in (I can see a visual difference pertaining to motion smoothing visually, somehow visually, when oversubscribing the GPU so that there is not enough room/fps, and when freeing the GPU where there is enough resources left for motion smoothing). But it is as-if it is going half way re projecting the pixels, which translates visually into juddering (de-doubling of the lines / features / etc...) when moving the head.

PS: no motion smoothing problems with Varjo Aero and Varjo Base set as the OpenXR runtime, so neither the RTX 4070 nor the most likely NVidia drivers have any problem regarding this. (so it seems).

[CptLucky8]

Motion Smoothing + RTX4070 was still not working with SteamVR 2.1.6 when I've tested a few days ago (I haven't tested 2.1.7 yet).

[nothingtofear]

I also still have the same issue with motion smoothing not working with RTX 4070 + valve index although I didn't notice any improvement by setting motion smoothing to "ENABLE" rather than "ALWAYS ON".

I completed a support ticket with steam support where they concluded that the GPU may be faulty but said that they didn't have any direct contact with the developers of SteamVR and weren't able to test the issue themselves. I then contacted Nvidia who eventually escalated the issue to their Level 2 Tech Support group back in June who they said would try and recreate the issue but that this could take a long time.

I also tried older versions of SteamVR to see if any might work. None did but I did notice that motion smoothing works in the "linux_v1.14" version that is still available in the betas dropdown but only for the left eye.

[CptLucky8]

I don't believe the issue comes from the NVidia itself, here is why: Varjo Motion Smoothing is working perfectly fine with the same hardware and AFAICT, they seem to be using NVidia OpticalFlow. AFAIK, SteamVR is also using NVidia OpticalFlow. So I'm only speculating here but I believe the issue might be located in SteamVR only.

I wouldn't be surprised it could be something as simple as an NVidia API return value which is different between a 20xxx and a 40xx, which SteamVR passes through with a 20xx and otherwise considers it being an error code with a 40xx. To illustrate what I mean, I'm thinking of something like the change in the NVEnc API return value which has been documented in the driver release notes for while:

------------------------------------------------------------------------------------------
In the NVIDIA driver, Release 415 and later, the behavior of the Video Codec SDK API
(NvEncCreateBitstreamBuffer) has been changed to return NV_ENC_ERR_UNIMPLEMENTED instead
of NV_ENC_SUCCESS when the encoder instance is configured to run in the motion estimation-
only mode. As an indirect consequence of this change, the AppEncME sample application
from the Video Codec SDK prior to SDK version 8.2.16 will crash due to a bug in the
NvEncoder class.
----------------------------------------------------------------------------------------

[Pausbe]

Same issue is happening with me. This was also a issue before SteamVR 2.0. I thought I was going crazy. 4070Ti here.

[aaron.leiby]

This was fixed in Nvidia driver version 555.xx which is available now.

[CptLucky8]

Originalmente postado por aaron.leiby:

This was fixed in Nvidia driver version 555.xx which is available now.

Thank you for the follow up Aaron.

However this raises a few questions from the following tests:

- Motion smoothing works fine with:

a) 4070 + 536.99, Win10 and WMR OXR + G2
b) 4070 + 536.99, Win10 and Varjo Base 3.10.2.20 (Sept. 2023)
c) 2070S + 536.99, Win10 and Valve Index on SteamVR

- Motion smoothing does NOT work with:

d) 4070S + 536.99, Win10 an Valve Index on SteamVR


In other words:
- 536.99 + WMR/Varjo + 2070S/4070 = motion smoothing fine.
- 536.99 + SteamVR + 2070S = motion smoothing fine.
- 536.99 + SteamVR + 4070 = no motion smoothing.

What does explain that 555.x would solve an issue that doesn't seem to affect any other VR compositor but SteamVR, which doesn't motion smooth with a 4070 but does motion smooth with 2070S (I suppose it still is but I haven't tested the 2070S card again since I've initially posted about this issue) ?!?!

[nothingtofear]

Originalmente postado por aaron.leiby:

This was fixed in Nvidia driver version 555.xx which is available now.

Thanks Aaron. This has fixed the issue for me with RTX 4070 and Valve Index.

[Maloon]

Originalmente postado por aaron.leiby:

This was fixed in Nvidia driver version 555.xx which is available now.

Hello, Aaron. This issue is present again with NVIDIA recent drivers. Last working driver was 572.16.