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vhaaland

v19.1 stutters UPS vs FPS

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I have my sim running unlimited FPS in P3Dv4 setting, vsync on and half refresh rate locked in Nvidia control panel. I have previously done extensive testing and found that the smoothest is when psxseecontraffic matches UPS with half refresh which in my case is 30 FPS. It's always locked at 30, but it seems psxseecontraffic in v 19.1 don't match this for some reason. I hope the option to lock the UPS can be added again, if not in the UI at least as a config file option.

As of v 19.1 there is just too much stutters


Vidar Haaland

 

System: Win10 Pro 64-bit, Intel Core i9-9900K (stock), Gigabyte Z390 AORUS ULTRA, Corsair Vengeance LPX DDR4 3200MHz 32GB, Corsair H150i PRO, Corsair MP510 960GB M.2 SSD, 
ASUS GeForce RTX 3080 ROG Strix OC

 

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I don't understand your settings. What fps do you have in P3D? Is it set at a fixed rate.?

Maybe if you understand how PSXT works it is possible for you to get better settings, so here we go:

Note that the fps in P3D/FSX fluctuates heavily, it is almost never a fixed rate (and thereby causing stutters). PSXT gets the fps number via simconnect, the values are with one decimal. PSXT smoothes the last 10 seconds to get an average FPS. This average is used as target for the update frequency it internally uses, which is called UPS. Contrary to the FPS the UPS is rock steady. So PSXT computes the next positions of aircraft at UPS rate, it puts these positions in a buffer, and then continues with the next slot.

Each time P3D produced a frame PSXT receives a message via simconnect. Upon that message PSXT pushes the latest available update  in P3D from the buffer described above. If a frame comes sooner then it should there will be no info in the buffer and if a frame comes later it will miss an update position and it may take already the next position. But the latter should not be a real problem while you are in fact already further in time.

So the smoothness of ai aircraft is dependent on smooth FPS (no stutters in frames)  and a UPS that is the same as FPS (in fact I take fps + 10% for the UPS to be sure of having positions in time).

One possible addition I could offer as a hidden parameter, is to let the UPS run at twice the FPS, so fluctuations in FPS will have less impact. However, I have run tests with that setting and did not notice any difference.

Maybe you should run some tests with VSYNC off etc. I run with vsync off, unlimited fps and  do not use the Nvidia control panel.

 

 

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It's obviously differences in the use of VSYNC on or off, as i run with this setting for years Adaptive (half refresh rate). My screen is 60HZ, and this forces 30HZ, aka 30 FPS when running borderless. In most situations my rig can get 30 FPS, and it will never go above that due to the VSYNC lock. This is the smoothest setting on my setup, and many others also run P3D with unlimited frames and VSYNC. If I switch CTRL+ENTER to not borderless, the FPS run up to 60HZ/AKA 60FPS as that is my screen limit. If I turn off VSYNC as you do, it causes more stutters on my setup. I have tested various settings many times, and always end up with this being the smoothest (aka no stutter) scenario.

It seems as if psxseecontraffic do not match the 30 HZ limit as there are more long frames/stutters when not using fixed UPS to match the VSYNC setting. Of course if the 30 FPS cannot be maintained in heavy scenery/weather conditions, there will be some stutters.

I did test this many times with psxseecontraffic, and also today with v19.1 vs 19.0 with fixed UPS and the latter is giving me best results.

Not every setup is the same, and some prefer VSYNC and others do not.

 

BTW this are my settings under [DISPLAY]

VSYNC=1
TRIPLE_BUFFER=1
UPPER_FRAMERATE_LIMIT=0

Edited by vhaaland

Vidar Haaland

 

System: Win10 Pro 64-bit, Intel Core i9-9900K (stock), Gigabyte Z390 AORUS ULTRA, Corsair Vengeance LPX DDR4 3200MHz 32GB, Corsair H150i PRO, Corsair MP510 960GB M.2 SSD, 
ASUS GeForce RTX 3080 ROG Strix OC

 

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I have also noticed deterioration of smoothness in 19.1
Before I was achieving reasonable smoothness but now without touching anything in a sim AI's are jumping about five times a second.
I started changing my settings and with unlimited it works OK but it’s useless for my set up.
I resorted to another type of locking 30 frames  which works OK but not as good as my previous set up that I developed over a long time.
I realize that many people are using unlocked but 30 lock and 1/2 refresh gives me excellent results.
maybe bring back synchronization in  config file might not be a tragic idea.
 
I wonder what the Vpilot is using, it receives position information every 5 seconds, but movement in between is continuous and smooth no matter what set up I have if it comes to frames and looking....( same for LorbyLive )
mike

Sim,PC, monitor,prescription glasses, chair.

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14 hours ago, vhaaland said:

It seems as if psxseecontraffic do not match the 30 HZ limit as there are more long frames/stutters when not using fixed UPS to match the VSYNC setting. Of course if the 30 FPS cannot be maintained in heavy scenery/weather conditions, there will be some stutters.

PSXSeecontraffic updates rock steady uptil 200 times/second with 100 live aircraft and 80 parked aircraft , that cannot be the problem, It must be irregular frames that cause stutters.

Edited by kiek

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12 hours ago, mike stryczek said:
I wonder what the Vpilot is using, it receives position information every 5 seconds, but movement in between is continuous and smooth no matter what set up I have if it comes to frames and looking....( same for LorbyLive )
 

VATSIM is a closed network with much more reliable and accurate data then the data from RealTraffic that is obtained from several ADS-B receivers world wide. And the position refresh is twice as fast as realtraffic. That's why I think...

Lorby uses a different approach (not slewing like PSXT) which has advantages but also disadvantages.

Edited by kiek

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Hi guys,

I have reverted PSXT to version 19.0. Will do some more testing with the VSYNC before I'll come up with a solution that will also satisfy your needs.

Regards,

Nico

Edited by kiek

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Here beta 19.2 with a new hidden parameter UPDATES_PER_SECOND, default value 30.

Edited by kiek

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On 10/21/2020 at 4:36 PM, kiek said:

Here beta 19.2 with a new hidden parameter UPDATES_PER_SECOND, default value 30.

will test tomorrow

TH Niko

Edited by kiek

Sim,PC, monitor,prescription glasses, chair.

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2 hours ago, mike stryczek said:
Unfortunately very quickly the old ugly 10 second shut down stopped PSXT

I think I know why and I have fixed that, please re-download.

Is UPS 30 the only value you are always using?

Edited by kiek

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THat's strange while the code is the same as 19.0.

To be sure you have the right version, here 19.2 beta. again (will show 19.3)

 

Edited by kiek

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