Cap your fps people (battlenonsense)

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ATi7500
Posts: 3
Joined: 07 Nov 2019, 09:44

Re: Cap your fps people (battlenonsense)

Post by ATi7500 » 07 Nov 2019, 09:52

Hello guys, new joiner here!

I've got a 60Hz IPS monitor, and I like to play almost exclusively with Vsync ON as I hate tearing.

Onto my questions:
  • Is the Unreal Engine "Framerate smoothing" an efficient framecap?
  • With Vsync ON, does it make any sense to keep it above refresh rate (as default for maxsmoothedframerate is 62)?
  • How come default maxsmoothedframerate isn't 60? What's the reasoning of keeping it 2 frames above?
  • I know that setting a framerate cap below refresh rate at a fixed value (59 with 60Hz) induces stutter every second. Does this happen in both on double buffered and triple buffered vsync?
Thanks in advance!

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jorimt
Posts: 825
Joined: 04 Nov 2016, 10:44

Re: Cap your fps people (battlenonsense)

Post by jorimt » 07 Nov 2019, 14:26

ATi7500 wrote:Is the Unreal Engine "Framerate smoothing" an efficient framecap?
In my experience, the Unreal Engine's in-game FPS limiting solution is a good one.
ATi7500 wrote:With Vsync ON, does it make any sense to keep it above refresh rate (as default for maxsmoothedframerate is 62)?
If your purpose is to avoid V-SYNC input lag, no.
ATi7500 wrote:How come default maxsmoothedframerate isn't 60? What's the reasoning of keeping it 2 frames above?
You'd have to ask the devs "why" on that.

But my assumption is when the limiter was originally created, and that value was initially decided on, 60Hz was predominate, and less was known/prioritized regarding V-SYNC input lag.
ATi7500 wrote:I know that setting a framerate cap below refresh rate at a fixed value (59 with 60Hz) induces stutter every second. Does this happen in both on double buffered and triple buffered vsync?
Yes.

So even though UE has a decent in-game limiter, if you're using standalone V-SYNC and want to prevent V-SYNC input lag while avoiding as much recurring stutter from this as possible, you're better off using an RTSS FPS at the decimal level, or some such other V-SYNC-only low lag method over an in-game limiter:
https://www.blurbusters.com/howto-low-lag-vsync-on/
Author: Blur Busters "G-SYNC 101" Series

Display: Acer Predator XB271HU OS: Windows 10 Pro MB: ASUS ROG Maximus X Hero CPU: i7-8700k GPU: EVGA GTX 1080 Ti FTW3 RAM: 32GB G.SKILL TridentZ @3200MHz

ATi7500
Posts: 3
Joined: 07 Nov 2019, 09:44

Re: Cap your fps people (battlenonsense)

Post by ATi7500 » 07 Nov 2019, 15:23

Thanks. Let's say I don't want to achieve the least possible amount of input lag, but settle with a low, constant input lag.
Does it make any difference to set a frame limiter to 60 (refresh rate being 59.9xx) with vsync on, compared not to having any frame limiter at all?

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jorimt
Posts: 825
Joined: 04 Nov 2016, 10:44

Re: Cap your fps people (battlenonsense)

Post by jorimt » 07 Nov 2019, 16:19

You'll get a little less input lag with a 60 FPS limit @60Hz, but you won't completely eliminate it like you would with 59 or 59.xx FPS.

The below image has scenarios depicting G-SYNC use, but the first three scenarios (starting from the top) apply to standalone V-SYNC as well in this respect:

Image
Author: Blur Busters "G-SYNC 101" Series

Display: Acer Predator XB271HU OS: Windows 10 Pro MB: ASUS ROG Maximus X Hero CPU: i7-8700k GPU: EVGA GTX 1080 Ti FTW3 RAM: 32GB G.SKILL TridentZ @3200MHz

ATi7500
Posts: 3
Joined: 07 Nov 2019, 09:44

Re: Cap your fps people (battlenonsense)

Post by ATi7500 » 07 Nov 2019, 17:49

Well guess what, just found this in the Engine.ini of a UE3 game

Code: Select all

MaxSmoothedFrameRate=59.990000
Which accepts decimals!

Measured the refresh rate of my Dell U2212HM to be 60.00x Hz, I guess I'm good to go :)

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jorimt
Posts: 825
Joined: 04 Nov 2016, 10:44

Re: Cap your fps people (battlenonsense)

Post by jorimt » 07 Nov 2019, 19:29

There's no guarantee it's as stable as RTSS at the decimal level, but you can give it a shot.
Author: Blur Busters "G-SYNC 101" Series

Display: Acer Predator XB271HU OS: Windows 10 Pro MB: ASUS ROG Maximus X Hero CPU: i7-8700k GPU: EVGA GTX 1080 Ti FTW3 RAM: 32GB G.SKILL TridentZ @3200MHz

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