Weird performance in VR with Quest 3 when turning head [Video]

[Alexified]

i9-13900K - 64GB - 4090 - Meta Quest 3 - TP-Link BE3600 dedicated WiFi 7

I'm experiencing strange changes in VR performance when I turn my head sideways. This also occurs during flight. It's clearly visible in the video, but without recording, the performance changes are even worse. What's going wrong here?

Video-Link (dont know how to embed):

DCS weird VR performance

[Qcumber]

46 minutes ago, Alexified said:

i9-13900K - 64GB - 4090 - Meta Quest 3 - TP-Link BE3600 dedicated WiFi 7

I'm experiencing strange changes in VR performance when I turn my head sideways. This also occurs during flight. It's clearly visible in the video, but without recording, the performance changes are even worse. What's going wrong here?

Video-Link (dont know how to embed):

DCS weird VR performance

It looks like a network issue. The network and decoding latencies go very high when you turn your head. Try reducing the bitrate and/or trying another video encoder such as h264+. Also make sure automatic bitrate is on. 

Edited April 17 by Qcumber

[dutchili]

Using Quest Link (USB) while flying/taxiing, you'll see the same thing, especially when turning your head past the 35-45 degree position (compared to straight ahead).
The world passes by faster when doing that, the CPU cannot produces enough frames to make a fluent picture. (less pronounced in slow aircraft).
As a result the GPU FPS also decreased (tightly coupled to CPU frames).
The more scenery, the more pronounced.

[Qcumber]

4 minutes ago, dutchili said:

Using Quest Link (USB) while flying/taxiing, you'll see the same thing, especially when turning your head past the 35-45 degree position (compared to straight ahead).
The world passes by faster when doing that, the CPU cannot produces enough frames to make a fluent picture. (less pronounced in slow aircraft).
As a result the GPU FPS also decreased (tightly coupled to CPU frames).
The more scenery, the more pronounced.

That is not normal with VD or Meta link. Unless you have low fps. And such an effect would not show in the home screen. 

[dutchili]

to my experience this is normal, and unwanted
Lowering the resolution significantly greatly reduces the issue.
headset is set at 72hz, even with ASW locked at 36 i can notice this (a bit)

[Qcumber]

43 minutes ago, dutchili said:

to my experience this is normal, and unwanted
Lowering the resolution significantly greatly reduces the issue.
headset is set at 72hz, even with ASW locked at 36 i can notice this (a bit)

What headset are you using and pc specs? It sounds like your DCS settings might be a bit too demanding. 

[dutchili]

quest 3 via meta quest link

i9-13900, rtx 4090, 32 gb.

i have oculus resolution set at max (1.3x) and DCS PD set to 1.3 too. This, combined with oculus sharpening gives nice crisp images.

All DCS settings are on high/ultra with only tree visibility set to 60% to prevent stutters.

Nividia settings are default except for max performance and low-latency = ultra.
 

The latest (yesterday) nvidia driver and oculus v76 greatly reduced ground stutters, especially with ASW locked at half-headset framerate.

There have been DCS version with better performance, it highly depends on the workload on the main threat. 
Statics are degrading FPS significanlty (airplanes parked at the airport).

The result change in the Viper with which threat is running the HUD made a good impact. The Viper instruments are stil a big impact on FPS generation.

[Qcumber]

4 minutes ago, dutchili said:

quest 3 via meta quest link

i9-13900, rtx 4090, 32 gb.

i have oculus resolution set at max (1.3x) and DCS PD set to 1.3 too. This, combined with oculus sharpening gives nice crisp images.

All DCS settings are on high/ultra with only tree visibility set to 60% to prevent stutters.

Nividia settings are default except for max performance and low-latency = ultra.
 

The latest (yesterday) nvidia driver and oculus v76 greatly reduced ground stutters, especially with ASW locked at half-headset framerate.

There have been DCS version with better performance, it highly depends on the workload on the main threat. 
Statics are degrading FPS significanlty (airplanes parked at the airport).

The result change in the Viper with which threat is running the HUD made a good impact. The Viper instruments are stil a big impact on FPS generation.

I'm looking into the stutter issue at the moment trying to work out what factors trigger it. I see it sometimes but not all the time. 

Just for clarity is the 1.3x resolution set in the Meta app or using ODT? If it is in the Meta app then this would make your total resolution (including PD x1.3) about 3800. That's a lot to handle, even for a 4090. What do your GPU render times look like? Have you tried using QVFR in fixed mode? You could then set the centre resolution to equivalent to 3800 and the periphery to about 2800. You would hardly notice the difference but it could give you a performance boost. 

[dutchili]

I have set 1.3 in the meta link app, not ODT.
It is a lot indeed, but not so much for the GPU according to the DCS FPS meter. That always states 'CPU bound', unless it greatly reduce PD and other graphic settings. Then it is GPU limited, which then in nonsense.

Even in heavy static embellished airports, the FPS is pretty steady at 72/73 Hz if not limited by ASW to 36, When i look around i immediately get some stutters in the scenery. Looking around again is usually better, but not perfect. I don't have that issue when i am all alone on the airfield.
I notice similar stutters when taxiing and still looking forward. I appears to me that the 'rate of change' for the 'direction of view' is too high for the CPU to generate 36+ frames.
When flying straight at low level and looking sideways, you see the same thing, unless all graphics settings are reduced to 'atari mode'

[Qcumber]

5 minutes ago, dutchili said:

I have set 1.3 in the meta link app, not ODT.
It is a lot indeed, but not so much for the GPU according to the DCS FPS meter. That always states 'CPU bound', unless it greatly reduce PD and other graphic settings. Then it is GPU limited, which then in nonsense.

Even in heavy static embellished airports, the FPS is pretty steady at 72/73 Hz if not limited by ASW to 36, When i look around i immediately get some stutters in the scenery. Looking around again is usually better, but not perfect. I don't have that issue when i am all alone on the airfield.
I notice similar stutters when taxiing and still looking forward. I appears to me that the 'rate of change' for the 'direction of view' is too high for the CPU to generate 36+ frames.
When flying straight at low level and looking sideways, you see the same thing, unless all graphics settings are reduced to 'atari mode'

It would be worth looking at GPU render times. These can often be borderline at the 13.89ms mark and lead to some missed frames that is not picked up in the average fps. 

[dutchili]

yeah, i do see spikes in those times when looking around or manouvering. It only becomes annoying when flying low over cities. All other situations are classified by me as 'not perfect, but not hindering gameplay'.
I do notice that a perfectly smooth gameplay make a big difference in perception: smooth = :), stutters are

I think (assumption) that the core of this issue is in how the rendering works / is linked to other computations / I/O.
Especially in VR. Reported frame rates in 2D are much higher, yet you see the exact same issues

[Alexified]

9 hours ago, Qcumber said:

It looks like a network issue. The network and decoding latencies go very high when you turn your head. Try reducing the bitrate and/or trying another video encoder such as h264+. Also make sure automatic bitrate is on. 

I turned on automatic bitrate and lowered the Mbps from 200 to 120. -> runs 98% smoothly.