[REPORTED]Stutters in the mountain impacting russian planes

[Chapa]

I though it was a specific Mig-19 issue but it appears that this bug affect most of the russian planes. I observed this bug in VR with a Rift S. I don't know if it occurs also in 2D.

 

The bug is reproducible with the mission provided in attachement. Flying in the mountains near tbilisi create stutters, specially strong with the Mig-19 but clearly visible with the following planes:

 

- Mig-15

- L-39C

- Mig-19

 

But the same spot, don't affect the F-86, F-18, M2000

 

It's probably caused by something specific to russian planes: ARK ?

 

In VR, even with every graphical settings at low, 80Hz stable or 40Hz stable, the stutters occurs.

 

The Mig-19 shows the strongest effect. The issue seems to avoid AWS to trig (with higher enough graphical settings). The Mig-19 has maybe other issues on top of this one...

 

Concerning the context:

- saved games folder recreated by renaming the older one

- metashaders/fxo dropped

- clean/repair done

- uninstall/reinstall the Mig-19 module

- Occulus Rift S current driver and beta drivers tested

 

I hope you will be able to reproduce this bug :)

 

Best regards,

Chapa

bug_caucasus_VR_stutters.miz

[Chapa]

@moderator: I miss to publish this thread in the bug report section... could you please move it there :doh:, or other part of the forum because it's probably not related to the Caucasus map, indirectly maybe...

 

Concerning the L-39C, the issue is clearly related to the avionics system behind the MRP-RV (Marker Beacon Receiver and Radio Altimeter) Switch, the stutter immediatly disappears when I turn it off, and reappears when turned on.

 

Turning of these systems in the Mig-19 doesn't solve the stutters. However, I tend to think that in the Mig-19, only the refreshing of the gauges is turned off but not the underlying processes/API calls.

 

It's important to note that, all my graphical settings are at the lowest possible values, the FPS is 80Hz stable with my Rift S, nvidia drivers up to date. My i8700 CPU could be the limitation factor by beeing not enough powerfull to hide the underlying problem.

 

The fact that the issue seems to occurs only in the Caucasus map let me think that it's more related to the beacons in the kHz range, less present in the other maps...

[BIGNEWY]

Hi Chapa

 

try disabling hot plug devices, let us know if you see a difference.

 

https://forums.eagle.ru/showthread.php?t=251377

[Chapa]

Hi Bignewy,

 

Thanks for your answer and suggestion. Unfortunatly, adding this instruction, confirmed by the log, doesn't solve the issue.

 

I reinstall all my system from scratch, erase everything, clean install, the minimum required to play DCS in VR:

 

- Windows 10 64 bits 1909 (up to date)

- Nvidia 441.87 drivers (up to date)

- NVidia Control Panel all with default settings

- Oculus 12.0.0.306.268 (the beta version doesn't solve the issue)

- Virpil software and firmware (up-to-date)

- No other softwares running like Voice Attack, Chrome, etc...

- No mod installed, never installed

- USB ports used only by joystick, throttle, rudders

- Rift S connected on its dedicated PCIe USB card, powered directly by the alimentation (no issue at startup)

 

Overall, my rig works like a charm and I am the kind of VR happy player with never an issue concerning performances, hardware etc...

 

I am quiet confident that there are no easy settings (BIOS/DCS graphical settings/NVidia) that could solve the issue. However, I also try the following settings but without success:

 

- Disable Hyperthreading in the BIOS

- Increase the VR pre-rendered frames in NVidia Control Pannel

- Enabling/Disabling Windows Game Mode, Full Screen Compatibility mode

 

With my setup, I can easy reproduce the issue with the mission provided in the first post, with the L-39C.

 

- Launch the mission with L-39C

- Bank left and right by looking the terrain as a pendulum

- Even with 80Hz (AWS OFF) or 40Hz (AWS ON) stable, there are big stutters like if the true FPS was 10

- Turn off the MRP-RV (Marker Beacon Receiver and Radio Altimeter) Switch, the stutters disappears and everything is smooth

- Turn it on and the stutters come back

 

In 2D, the FPS instability is also visible from the FPS counter but because the FPS is so high, it's not noticible from a gameplay perspective.

 

The fact that I can turn on/off the stutters by enabling/disabling some L-39 avionics tends to proove that some process behind the scene create the stutters, or at least push my CPU (probably) outside its allowed flying envelope :)

 

Note that I discovered this issue and workaround because I just bought the Mig-19 and notice these stutters from its Caucasus free flight mission. By investigating in the forum, some people says that the Mig-19 bad VR performances was visibile only on the Caucasus map and it appears to be relatively true for me also... I deduced from there, that RSBN, kHz beacon, specific stuff for russian planes was specific to the Caucasus map and without surprise, I reproduced the issue with most of the old russian planes. The L-39 is good because I can disable the stutters but I really think that there something serious behind the scene.

 

Hope you will be able to reproduce the issue. If there are some metrics, measures, monitoring, debug tool to install and insight I could provide, don't hesitate to ask, I have time and would be happy to help.

 

Best regards,

Chapa

[Chapa]

@Bignewy

 

Hi Bignewy,

 

Do you have some other idea about this issue, please ?

 

I did some monitoring in VR with the provided mission and L-39C to analyze the CPU/GPU usages. It appears that with AWS Off, FPS 80Hz, the usage are:

 

CPU: about 26% stable

GPU: about 70% stable

 

It means that the CPU/GPU achieve easely the 80Hz with the defined graphical settings.

 

However, the stutters are present and when I disable the MRP-RV they disapears. When enabled, the FPS is 80Hz but fall down to 73 for a fraction of second and come back to 80 and falldown soon after to 73 again etc... With the switch disabled, the FPS is 80Hz perfectly stable. Switching ON/OFF has no impact on the CPU/GPU usage. I don't see any change in the graphs of the 6 CPUs/ 12 Threads nor the GPU graph...

 

VR Headset (at least the Rift S) don't like when the FPS isn't 80Hz or 40Hz, all FPS in between create stutters.

Something behind the MRP-RV switch create a FPS drop with a duration shorter than the time constant allowing AWS to trig. If AWS is forced, it avoid the proper creation of the interpolated frame... It's my supposition...

Very short job computed on the main loop ?

 

Thanks in advance for your help,

Best regards,

 

Chapa

Edited February 5, 2020 by Chapa

[BIGNEWY]

Hi

 

I am not sure, to be honest it can be difficult to diagnose stutter.

 

Can you attach your dcs log and also a dxdiag we may see some clues in them.

 

Thanks

[Chapa]

Hi Bignewy,

 

Thanks you for your help. You'll find in attachment the log and dxdiag files.

 

The log correspond to a very short session:

 

- Load DCS

- Load the mission in attachment in the first post with the L-39

- Bank left/right with the MRP-RV Switch enabled => stutter

- Bank left/right with the MRP-RV Switch disabled => no stutter

- Bank left/right with the MRP-RV Switch enabled => stutter again

- Exit DCS

 

Hope it will help.

 

Best regards,

Chapa

dcs_log.txt

DxDiag.txt

[BIGNEWY]

Thank you,

 

I can see nothing obvious in your log or dxdiag and I have tried your mission with my VIVE Cosmos and did not get any stutter in the L-39.

 

FPS at altitude was 90 and at lower altitude 45 but no stutter at all, I will ask another team member to check.

 

Can you do a short track replay after you see the issues with MRP-RV Switch enabled

 

thanks

[Chapa]

Here is a track. The stutters are presents at the start of the mission because the siwtch is enable. Near the end of the track, I stop to bank few seconds, disable the switch and bank again but without stutters.

 

UPDATE:

I tried to create a movie with my iphone from one of the lens but it's not visible... too bad quality, unstable and hard to be on the optical path... I checked if it is only visibile in stereoscopic vision by closing one eye in the HMD. Each eye see stutters.

 

UPDATE 2:

I said that I was able to reproduce these stutters with most of the russian planes.

The Mig-15 suffers the same issue and it appears that it's even more interesting with this beauty because it has separate switches for the radio altimeter and beacon navigation. I can switch ON/OFF the stutters by turnig ON/OFF the ARC switch this time. Turning ON/OFF the radio altimeter switch change nothing.

It tends to confirms my feeling about an issue related to the kHz beacons

 

I will try to reproduce the issue in other map near one of the rarer kHz beacon. One player says that he has issue with the Mig-19 in Caucasus map but not in the others. We will see.

Note that I share the exactly same CPU with this player: i7 8700 (non k version)

 

Thank you for the time you give me

L39_stutters.trk

Edited February 6, 2020 by Chapa

[Lange_666]

Note that I share the exactly same CPU with this player: i7 8700 (non k version)

 

 

Not CPU depended, i have a i7 4770K and when replaying your track the stutter is clearly visible in VR looking either left or right. No jump in FPS when it happens.

[BIGNEWY]

Hi all.

 

The team has reproduced and reported.

 

Marker receiver seems to be the issue

 

Thank you for the reports.

[Chapa]

It seems that the last patch has fixed the issue, no more stutters for me at least.

I imagine it is related to this fix:

• Fixed bug in the global Radio that should have led to some improvement of game performance.

Thanks you !