MadDog

Prepar3D Vsync/Triple Buffering... Placebo?

24 posts in this topic

I'm curious about what the Vsync/Triple Buffering options in Prepar3D actually do?  Through various tests, I've confirmed that Vsync in Prepar3D is in fact being provided by Windows Desktop Composition (aka "DWM", aka "Aero").  I am also pretty confident that Desktop Composition is already triple buffered.  This can easily be confirmed by turning off Vsync in Prepar3D and observing that there is still no screen tearing.

Going a step further, disabling Desktop Composition in Windows (and reenabling Vsync/Triple Buffering in Prepar3D) will result in very noticable tearing in the sim (not to mention extremely smooth frames :happy:).  So what is the purpose of those options?  I'm unsure if it's totally placebo because the Prepar3D Vsync does appear to slightly reduce tearing with Desktop Composition disabled; but it certainly doesn't eliminate it.

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1 minute ago, laserit said:

Full Screen

There is no Full Screen in Prepar3D.  Only borderless windows (unfortunately).

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8 minutes ago, MadDog said:

There is no Full Screen in Prepar3D.  Only borderless windows (unfortunately).

If your in window mode, go to options/display and change your resolution. When you return to the sim, nothing will change until you hit alt_enter or switch to full screen in the menu.

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This is useful if you are in SLI Surround to prevent tearing, I have to have enabled in Nvidia CC.  

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13 minutes ago, angeli662 said:

This is useful if you are in SLI Surround to prevent tearing, I have to have enabled in Nvidia CC.  

Interesting. So would it only apply to SLI?  Personally, I've discovered that sync-induced micro-stutters are slightly better with Vsync/Triple buffering disabled in Prepar3D (using a single card on a single display).  I wonder if it adds additional processing for multiple monitors into the mix.

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4 minutes ago, MadDog said:

Interesting. So would it only apply to SLI?  Personally, I've discovered that sync-induced micro-stutters are slightly better with Vsync/Triple buffering disabled in Prepar3D (using a single card on a single display).  I wonder if it adds additional processing for multiple monitors into the mix.

Not sure but in my case Triple displays and Triple cards  and SLI s. is very noticeable when comes to vertical sync. 

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It does work for me, absolutely and what's even crazier, it doesn't even need to be at the V-Sync range to be effective. I have my sim framerate capped well below the actual V-Sync level but enabling V-Sync and Triple Buffering yields a smoother image when panning. I also tried uncapping the sim and the second I enable TB, I'm seeing a consistent reduction of 2ish FPS. So it's doing something. I can then disable it and the panning already feels a bit more direct but also less smoothed out. So Triple Buffering is definitely part of my setup to give me a smooth experience. 

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I have 1070's in SLI and do not use vSync or TB and I have no tearing or lack of smoothness. This was the same on my old resolution 1920x and my new resolution 3560x.  FWIW, I did have it in FSX, when I turned my head using TIR the cockpit window edges would tear badly.

Vic

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28 minutes ago, vgbaron said:

 FWIW, I did have it in FSX, when I turned my head using TIR the cockpit window edges would tear badly.

Yes, that would make sense since FSX automatically disabled Aero and Desktop Composition - I don't think you could vsync it in a window.  When running in Full Screen Exclusive mode, FSX required Vertical Sync to be enabled at the driver level (Oh, how I miss my half vertical refresh!)

I'm still unclear why these options are provided in Prepar3D's UI when WIndows already has them enabled by default.  Is it supposed to be some sort of "enhanced" Vsync?

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23 minutes ago, MadDog said:

Yes, that would make sense since FSX automatically disabled Aero and Desktop Composition - I don't think you could vsync it in a window.  When running in Full Screen Exclusive mode, FSX required Vertical Sync to be enabled at the driver level (Oh, how I miss my half vertical refresh!)

I'm still unclear why these options are provided in Prepar3D's UI when WIndows already has them enabled by default.  Is it supposed to be some sort of "enhanced" Vsync?

Nvidia Control Panel and Nvidia Inspector also has the option and can be Game specific.

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3 hours ago, laserit said:

If your in window mode, go to options/display and change your resolution. When you return to the sim, nothing will change until you hit alt_enter or switch to full screen in the menu.

But full screen in p3d isn't really full screen. It's a borderless window. Always had been and it's why the 1/2 refresh setting doesn't work in nvidia inspector. I think this is what the poster is referring to.

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8 minutes ago, GHarrall said:

But full screen in p3d isn't really full screen. It's a borderless window. Always had been and it's why the 1/2 refresh setting doesn't work in nvidia inspector. I think this is what the poster is referring to.

All I know is that if I change the screen resolution setting inside of P3D it will ignore the change in windowed mode and the change will occur as soon as you enter fullscreen mode. So there definitely is something different between the two modes besides the removing of borders.

it will also switch back and forth between the two resolutions as you switch back and forth between windowed and fullscreen modes. 

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24 minutes ago, laserit said:

All I know is that if I change the screen resolution setting inside of P3D it will ignore the change in windowed mode and the change will occur as soon as you enter fullscreen mode. So there definitely is something different between the two modes besides the removing of borders.

There is nothing different other than the fact that the resolution is not changed until the screen-filling window is created.  Once the Prepar3D window is open, if you ALT+TAB back to the desktop, you'll notice that the desktop resolution has changed to match whatever you selected in Display Options.  It is no different than selecting a different desktop resolution beforehand and expanding a window to fill it (except that the borders are hidden).

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Also, if Prepar3d's  Vsync does nothing then why does my frame rate change when I deactivate Vsync? 

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