Simmers and FPS

[CaptKornDog 281]

Running on a 144 Hz Gsync monitor selected down to 120 Hz, I’d love to see an x/3 and even x/4 option in RTSS.

[jay281 33]

7 hours ago, ttbq1 said:

I have it and it is working great. 4k monitor on 60hz, NVI at 1/2 refresh rate with TB ON. P3D V4.5 FPS locked at 33, FFTF with AGL 0-4000 range 0.01-0.20.

Steady FPS at 30, and smooth as silk.

1/2 refresh (NVI) won't work as P3D is not exclusive full screen. 

Edited December 30, 2019 by jay281

[Bob Scott 7,715]

54 minutes ago, CaptKornDog said:

Running on a 144 Hz Gsync monitor selected down to 120 Hz, I’d love to see an x/3 and even x/4 option in RTSS.

Kyle, I'm puzzled why you'd want to do that.  If you just use the internal frame rate limiter together with G-Sync, you can avoid stutters, because the display will sync to the GPU output at whatever rate that is.

I'm not sure why, with a G-Sync variable refresh rate display system, we'd want to constrain frame rates with RTSS, given that RTSS' intended purpose is to emulate the smooth display we already get with a VRR display system, essentially producing something as smooth as G-Sync but on a fixed-rate monitor.

My portable sim box has a 1080Ti and a 144 Hz 24" Dell 2560x1440 G-Sync monitor.

I set my frame rates to 29 with the internal P3D limiter, and the very occasional dip below 29 is really not noticeable, as the display adapts to those momentary drops in real time.  I chose 29 because when the frame rate drops below 30, the G-Sync hardware has the GPU send each frame twice at double the frame rate (e.g. if P3D is outputting at 25 fps the GPU sends each frame twice at 50 fps to keep within the hardware's scan rate range of 30-144 Hz).  So if frame rates are allowed to wobble back and forth across the 30fps scan rate lower threshold on my monitor, the back and forth switching between displaying single frames at the GPU rate when above 30fps and double-frames when below 30 *is* noticeable.  With 29 set in P3D everything goes as double frames at double the actual frame rate, which is double-frames at 58fps probably 99% of the time with short excursions below that, also not noticeable because they're all sent double-frame double-rate as well.

Regards

[CaptKornDog 281]

2 hours ago, w6kd said:

Kyle, I'm puzzled why you'd want to do that.  If you just use the internal frame rate limiter together with G-Sync, you can avoid stutters, because the display will sync to the GPU output at whatever rate that is.

I'm not sure why, with a G-Sync variable refresh rate display system, we'd want to constrain frame rates with RTSS, given that RTSS' intended purpose is to emulate the smooth display we already get with a VRR display system, essentially producing something as smooth as G-Sync but on a fixed-rate monitor.

My portable sim box has a 1080Ti and a 144 Hz 24" Dell 2560x1440 G-Sync monitor.

I set my frame rates to 29 with the internal P3D limiter, and the very occasional dip below 29 is really not noticeable, as the display adapts to those momentary drops in real time.  I chose 29 because when the frame rate drops below 30, the G-Sync hardware has the GPU send each frame twice at double the frame rate (e.g. if P3D is outputting at 25 fps the GPU sends each frame twice at 50 fps to keep within the hardware's scan rate range of 30-144 Hz).  So if frame rates are allowed to wobble back and forth across the 30fps scan rate lower threshold on my monitor, the back and forth switching between displaying single frames at the GPU rate when above 30fps and double-frames when below 30 *is* noticeable.  With 29 set in P3D everything goes as double frames at double the actual frame rate, which is double-frames at 58fps probably 99% of the time with short excursions below that, also not noticeable because they're all sent double-frame double-rate as well.

Regards

G-Sync does not work with my particular P3D set up, even with settings that maintain 38+ FPS in nearly any scenario.  All other games, no issues with it.  Otherwise, yes, I'd love to use G-Sync.  Anything below about 36 FPS is very noticeable on my system.  41+ is the sweet spot.  Only way I can minimize stutters is a combination of RTSS and monitor refresh rate based on hours (and I really mean weeks) of changing variables one by one and experimenting.

Edited December 31, 2019 by CaptKornDog

[newtie 533]

10 hours ago, ttbq1 said:

I have it and it is working great. 4k monitor on 60hz, NVI at 1/2 refresh rate with TB ON. P3D V4.5 FPS locked at 33, FFTF with AGL 0-4000 range 0.01-0.20.

Steady FPS at 30, and smooth as silk.

Same here. Closest to FSX 1/2 Vsync I've found.

[Bob Scott 7,715]

3 hours ago, CaptKornDog said:

G-Sync does not work with my particular P3D set up, even with settings that maintain 38+ FPS in nearly any scenario.  All other games, no issues with it.  Otherwise, yes, I'd love to use G-Sync.  Anything below about 36 FPS is very noticeable on my system.  41+ is the sweet spot.  Only way I can minimize stutters is a combination of RTSS and monitor refresh rate based on hours (and I really mean weeks) of changing variables one by one and experimenting.

I'm curious what monitor you're using, and its age...wondering if maybe this is a G-Sync v1/v2 vs v3 issue.

[CaptKornDog 281]

2 minutes ago, w6kd said:

I'm curious what monitor you're using, and its age...wondering if maybe this is a G-Sync v1/v2 vs v3 issue.

Predator/ACER XB271HU.  About 18 months old.

 

Setting your recommended 29 FPS limiter in sim becomes a nightmare at 144 Hz.  Panning results on a lot of ghosting and stuttering, nothing is readable or smooth.  Oh well.

[Christopher Low 5,332]

If I could get a minimum of 20fps everywhere in my flight simulator at high detail levels (without appreciable stutters), I would be ecstatic.

Edited December 31, 2019 by Christopher Low

[chapstick 2,757]

17 hours ago, w6kd said:

Kyle, I'm puzzled why you'd want to do that.  If you just use the internal frame rate limiter together with G-Sync, you can avoid stutters, because the display will sync to the GPU output at whatever rate that is.

I'm not sure why, with a G-Sync variable refresh rate display system, we'd want to constrain frame rates with RTSS, given that RTSS' intended purpose is to emulate the smooth display we already get with a VRR display system, essentially producing something as smooth as G-Sync but on a fixed-rate monitor.

My portable sim box has a 1080Ti and a 144 Hz 24" Dell 2560x1440 G-Sync monitor.

I set my frame rates to 29 with the internal P3D limiter, and the very occasional dip below 29 is really not noticeable, as the display adapts to those momentary drops in real time.  I chose 29 because when the frame rate drops below 30, the G-Sync hardware has the GPU send each frame twice at double the frame rate (e.g. if P3D is outputting at 25 fps the GPU sends each frame twice at 50 fps to keep within the hardware's scan rate range of 30-144 Hz).  So if frame rates are allowed to wobble back and forth across the 30fps scan rate lower threshold on my monitor, the back and forth switching between displaying single frames at the GPU rate when above 30fps and double-frames when below 30 *is* noticeable.  With 29 set in P3D everything goes as double frames at double the actual frame rate, which is double-frames at 58fps probably 99% of the time with short excursions below that, also not noticeable because they're all sent double-frame double-rate as well.

Regards

Do you not get a subtle "flickering" effect on your screen with G-sync in P3D? That's what happens on my monitor, so I don't use G-sync in P3D. I think it's because 30 FPS is near the bottom of the range that G-sync can work in.

[Bob Scott 7,715]

28 minutes ago, Chapstick said:

Do you not get a subtle "flickering" effect on your screen with G-sync in P3D? That's what happens on my monitor, so I don't use G-sync in P3D. I think it's because 30 FPS is near the bottom of the range that G-sync can work in.

G-Sync does work below 30 fps...that 30fps limit is driven by the scan rate of the monitor hardware, and G-Sync compensates for that by sending each frame twice at double the frame rate when the sim's frame rate drops below the lower scan rate threshold.

That's exactly why I lock frames at 29 with the limiter.  That flicker appears to be caused by the video system ping-ponging between 30 and 58 fps as the frame doubling cycles on and off.  When P3D is at 29 fps, the monitor is getting double frames at 58 fps, and when it hits 30, it gets single frames at 30 fps.  I'm fairly confident that's what was causing the issue.

 

[chapstick 2,757]

32 minutes ago, w6kd said:

G-Sync does work below 30 fps...that 30fps limit is driven by the scan rate of the monitor hardware, and G-Sync compensates for that by sending each frame twice at double the frame rate when the sim's frame rate drops below the lower scan rate threshold.

That's exactly why I lock frames at 29 with the limiter.  That flicker appears to be caused by the video system ping-ponging between 30 and 58 fps as the frame doubling cycles on and off.  When P3D is at 29 fps, the monitor is getting double frames at 58 fps, and when it hits 30, it gets single frames at 30 fps.  I'm fairly confident that's what was causing the issue.

 

Curious how that doesn't work for me -- what Nvidia driver are you on?

[Bob Scott 7,715]

22 minutes ago, Rob_Ainscough said:

I’ve never been a fan of G-sync and don’t understand why someone would want a variable frame-time?  Its the variance the brain detects and hence is the distraction.

Use RTSS frame limiter if monitor can’t go below 60Hz ... just make sure P3D water setting if not at Ultra, the CUDA support seems cause irregularities.

Cheers Rob

The ideal is a steady frame rate, but when those occasional excursions below the target rate happen, that's where G-Sync shines.  I find it especially helpful in FSX, where I still go on occasion to fly a few revered oldies like the PMDG MD-11.

Cheers

[CaptKornDog 281]

Speaking for P3D, I’m still having a hard time comprehending how 29 locking internally or externally to 29 FPS sends double the frames/58 to achieve smoothness on my system.  Sure, I can have 28-29 FPS pegged in nearly every scenario with my settings under a 7700K @ 4.8GHz and a slightly overclocked 1080 Ti with MSAA settings, middle-of-the-road sliders.

 

Trying that in combination with forcing G-Sync on (as well as combining with forcing Vsync off and off), brings my picture to a choppy mess.  Hand flying and panning/reading gauges becomes more difficult.  Setting the limiter to above that, say locking in anywhere between about 40-60 FPS, offers a far smoother picture displayed (but sure, has far more variance). Tried at 144, 120, 100, 85, and 60 Hz on my monitor with similar results.  Guess my system just behaves different.

I’d be perfectly content running 29 FPS locked leaving my panel at 144 Hz if it were smooth.  I’d rather have the balance of consistency and smoothness over the eye candy and fluctuations any day.

 

Edited December 31, 2019 by CaptKornDog

[Lorby_SI 2,036]

On 12/29/2019 at 8:06 PM, PATCO LCH said:

Seems I read that a motion picture sets at 25 FPS because that's all the human eye and brain can process. So I have often wondered if anything above that serves any purpose in the sim other then bragging rights. As long as you have relatively smooth performance is there any point to 25-30FPS Plus?

IMHO, if that were true, then this would only work when the refresh rate of your eyes was perfectly synchronized to the 25 FPS on screen. If the movie reel is not startetd in exactly the right millisecond, you would have flickering, because you would never see an entire frame, only parts of it. The refresh and processing rate of the eye must be significantly higher than 25FPS, otherwise no two people could watch a movie at the same time.

The human eye and brain aren't digital circuits, AFAIK what they do cannot even be described in those computerized terms. What you percieve as "good" or "smooth" is a highly individual value, which is different for everyone. Just like the other senses, touch, taste, hearing, etc.. Meaning, there is no point at all in comparing or discussing it...

As for FPS in the sim, with many of my addons I made the observation that on the ESP platform simulated objects are not processed in sync with everything else. The higher the FPS go, the more they start to stutter and flutter, unlimited FPS being the worst. This is most evident in AI aircraft and attached simobjects, and it seems to have become worse in the latest versions of P3D. If there are moving objects in the sim, a 30-ish FPS limit is often required to make their movement appear smooth in relation to your own.

Best regards

Edited December 31, 2019 by Lorby_SI

[Bob Scott 7,715]

6 hours ago, Chapstick said:

Curious how that doesn't work for me -- what Nvidia driver are you on?

432.00

2 hours ago, CaptKornDog said:

Speaking for P3D, I’m still having a hard time comprehending how 29 locking internally or externally to 29 FPS sends double the frames/58 to achieve smoothness on my system.  Sure, I can have 28-29 FPS pegged in nearly every scenario with my settings under a 7700K @ 4.8GHz and a slightly overclocked 1080 Ti with MSAA settings, middle-of-the-road sliders.

 

Trying that in combination with forcing G-Sync on (as well as combining with forcing Vsync off and off), brings my picture to a choppy mess.  Hand flying and panning/reading gauges becomes more difficult.  Setting the limiter to above that, say locking in anywhere between about 40-60 FPS, offers a far smoother picture displayed (but sure, has far more variance). Tried at 144, 120, 100, 85, and 60 Hz on my monitor with similar results.  Guess my system just behaves different.

I’d be perfectly content running 29 FPS locked leaving my panel at 144 Hz if it were smooth.  I’d rather have the balance of consistency and smoothness over the eye candy and fluctuations any day.

 

The problem is that as soon as you exceed the lower scan rate threshold (30 Hz for the XB271HU), the frame doubling stops, because at 30 fps, you are now within the hardware scan rate range of the monitor (30-144Hz).  As soon as you drop below 30, then frame doubling begins, and at 29fps and below each frame is sent twice, but at double the application's output frame rate, so at 29 fps the GPU sends two duplicate frames, but at 58 fps.  So as you wobble across that 30fps "barrier" the hardware is rapidly fluctuating between 30 and 58 fps.  But if you constrain the application's frame rate to below 30, then everything is doubled...no more waffling back and forth.  There will be small fluctuations in the frame rate, but those don't reach out and grab you like those rapid and large oscillations.

One thought...make sure you have G-Sync enabled for both full and windowed screens in nVidia Control Panel, as P3D is a windowed application, unlike most other 3D games.

I would also use a utility to monitor the actual hardware frame rate...I don't remember the name of the one I used when doing the 9900K build.