How does limiting 2 fps below refresh rate help mouse lag?

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nimbulan
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Re: How does limiting 2 fps below refresh rate help mouse la

Post by nimbulan » 04 Jan 2014, 18:28

Chief Blur Buster wrote:
RealNC wrote:Skyrim is extremely weird in that regard. In 3rd person view, there's almost zero input lag. Mouse feels very snappy. Switch to 1st person, the mouse feels very "floaty". Try to explain *that* one.
It's very possible it is game engine coding; the different view modes may have different timings of rendering relative to input reads (keyboard/mouse).
With all the other bugs and weirdness in that engine, I would not be at all surprised.

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Re: How does limiting 2 fps below refresh rate help mouse la

Post by SS4 » 04 Jan 2014, 18:43

So if lightboost behave the best with vsync on the same could be said when/if it becomes compatible with gsync then? Or much better since you can't guarantee steady FPS 100% of the time!

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Dustmuffins
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Re: How does limiting 2 fps below refresh rate help mouse la

Post by Dustmuffins » 04 Jan 2014, 22:11

RealNC wrote:Skyrim is extremely weird in that regard. In 3rd person view, there's almost zero input lag. Mouse feels very snappy. Switch to 1st person, the mouse feels very "floaty". Try to explain *that* one.
I would recommend going into SkyrimPrefs.ini and editing the following value to this: bMouseAcceleration=0 as well as Skyrim.ini and setting iPresentInterval=0 if you havn't already.

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Re: How does limiting 2 fps below refresh rate help mouse la

Post by Chief Blur Buster » 04 Jan 2014, 23:08

SS4 wrote:So if lightboost behave the best with vsync on the same could be said when/if it becomes compatible with gsync then? Or much better since you can't guarantee steady FPS 100% of the time!
GSYNC doesn't need VSYNC ON or VSYNC OFF.

If (and when) strobing becomes available simultaneously with GSYNC, you won't need to worry about VSYNC ON versus VSYNC OFF. However, variable-rate strobing is a difficult engineering challenge at this time, but that could potentially be continuous motion fluidity nirvana, for GPU's running at >75fps (since you don't want to strobe at less than 75Hz, due to flicker).

For now, GSYNC and strobing have separate advantages.
GSYNC -- eliminate stutters/tearing but not motion blur -- good for low/variable framerates
strobing -- eliminate motion blur but not stutters/tearing -- good for high/consistent framerates (framerate equalling stroberate, at least)

That said if you want the best of all worlds, you have got to pony up on GPU horsepower (e.g. Titan's, R290X's, etc). To get strobing+VSYNC ON (with no frame drops) can simultaneously eliminate motion blur/stutters/tearing all at once, but only if you manage framerates matching refresh rates.
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Re: How does limiting 2 fps below refresh rate help mouse la

Post by SS4 » 04 Jan 2014, 23:19

Yeah the only option for best result is GPU horsepower with lightboost like you said.
But i know g sync and vsync are different, i was just making a parallel since gsync is basically like vsync but variable instead of static.

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Re: How does limiting 2 fps below refresh rate help mouse la

Post by Dustmuffins » 05 Jan 2014, 03:36

Chief Blur Buster wrote:(since you don't want to strobe at less than 75Hz, due to flicker).


I would imagine that you could hold the individual strobe longer in the "on" position to account for the decline in frequency and have the "off" pulse be just as long as it would be at 144hz. It would just have to be a dimmer "on" pulse to account for the longer hold time. That way the eye would only precieve the "off" pulse as well as a 144hz flicker(which lasts around 1/288th of a second I assume)

It's conceivable that you could have this work to as low as any fps as you wanted. Imagine you're running a game at 10 fps. You would have 10 long duration and relatively dim "on" pulses and 10 (1/288)th "off" pulses each second. That would be pretty much undetectable.

Am I on to something here or completely off my rocker?

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Re: How does limiting 2 fps below refresh rate help mouse la

Post by Chief Blur Buster » 05 Jan 2014, 03:42

Dustmuffins wrote:I would imagine that you could hold the individual strobe longer in the "on" position to account for the decline in frequency and have the "off" pulse be just as long as it would be at 144hz. It would just have to be a dimmer "on" pulse to account for the longer hold time. That way the eye would only precieve the "off" pulse as well as a 144hz flicker(which lasts around 1/288th of a second I assume)
The ON:OFF ratio needs to be maintained, to maintain brightness during strobe rate changes. e.g. 25% ON / 75% OFF, as an example. So the lengths of the ON and OFF would concurrently go up / concurrently go down.

(1) You need to stick to one strobe per refresh for the motion blur elimination effect. As a result, as strobe rate goes down, the strobes needs to become longer to maintain brightness (maintain the duty cycle). The strobe becomes longer, the dark period becomes longer.

(2) For an alternative algorithm, you can have the strobes fade to a steady state, as the framerates go lower. I've added this information to Electronics Hacking: Creating a Strobe Backlight. There are two ways I see of doing this, diagrammed.

This is a more advanced topic, which would be good for discussion in a separate thread, or perhaps in Area 51. :)
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Re: How does limiting 2 fps below refresh rate help mouse la

Post by Dustmuffins » 05 Jan 2014, 05:12

Chief Blur Buster wrote:This is a more advanced topic, which would be good for discussion in a separate thread, or perhaps in Area 51. :)
Sounds good. I'll need to do study up first. Awesome link.

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Re: How does limiting 2 fps below refresh rate help mouse la

Post by TheLeetFly » 05 Jan 2014, 14:15

After reading this topic I tried several different refresh-rates myself and will post my thoughts and experiences about them:
Note: I am using an Asus VG278HE with 120Hz Lightboost @ 10% Brightness.

My normal BF3 gameplay depends on the 120Hz Lightboost in combination with a 125fps Framelock [VSync off].
I had [and will forever] set the pre-rendered frames to the lowest value (1). Additionally i forced BF3 to prerender zero frames with "RenderDevice.ForceRenderAheadLimit 0".

Results:
120fps will cause random tearing all over my screen. Not much, but enough to disturb my gameplay and distract me.
118fps AS WELL as 119 fps will cause little tearing only in the bottom of the screen. As Mark described it is only visible in the middle of the bottom.
At 121fps i hardly sense tearing, it is nearly completely gone.

I had it locked on 125fps, because this is a very stable value which would not drop, and it is a little further away from 120 so i get rid of tearing.

For "mouse lag" i could not tell any difference between these various fps locks. Maybe this is caused by my disabled VSync.
I always considered my mouse as smooth and fluid and can not describe it as a weak point influencing my gameplay. For anyone interested in my mouse: Zowie eVo EC1 Optical Sensor @ 1000Hz / 1150 dpi / BF3 sens: 0.049841 Sens / 27 cm for 360°.

Should I test it again with VSync on and post my results?
What would you consider as the best "framelock-value"?

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Re: How does limiting 2 fps below refresh rate help mouse la

Post by Chief Blur Buster » 05 Jan 2014, 14:32

TheLeetFly wrote: Results:
120fps will cause random tearing all over my screen. Not much, but enough to disturb my gameplay and distract me.
118fps AS WELL as 119 fps will cause little tearing only in the bottom of the screen. As Mark described it is only visible in the middle of the bottom.
At 121fps i hardly sense tearing, it is nearly completely gone.

I had it locked on 125fps, because this is a very stable value which would not drop, and it is a little further away from 120 so i get rid of tearing.

For "mouse lag" i could not tell any difference between these various fps locks. Maybe this is caused by my disabled VSync.
I always considered my mouse as smooth and fluid and can not describe it as a weak point influencing my gameplay. For anyone interested in my mouse: Zowie eVo EC1 Optical Sensor @ 1000Hz / 1150 dpi / BF3 sens: 0.049841 Sens / 27 cm for 360°.

Should I test it again with VSync on and post my results?
What would you consider as the best "framelock-value"?
Very good observations, and this is actually normal in certain games that does adaptive VSYNC (game engines can do software based adaptive VSYNC behaviors independently of drivers via polling RasterStatus.ScanLine or RasterStatus.WaitForVBlank). In a situation of a slightly lower framecap than refresh rate during adaptive VSYNC, the tearing tends to linger closer to the bottom edge of the screen.

I would not expect differences in input lag for the Battlefield series for minor differences in frame caps. The low tickrate, the variability of lag gunshot-to-gunshot, and the adaptive behavior will cause negligible differences in input lag between different close frame rates. My high speed camera test showed 20ms variability in gunshot-to-gunshot input lag in Battlefield 4, this is going to be featured in my GSYNC article #2.

If you are very sure the game is not running in adaptive VSYNC, and the game software isnt doing internal adaptive VSYNC during frame capping, you might be seeing tearing at bottom edge because of higher contrast motion activity occuring at the bottom edge of your screen, or simply where your eyes are usually pointed at (crosshairs area and the gun below, with muzzle flash occurring in the region you describe). But your description also describes adaptive VSYNC behavior.

Only some game engines and configurations exhibit a sudden step of increased lag the moment your frame rate cap goes one frame per second above refresh rate.

125fps is often ideal for many users because it is distinctly away from harmonics, and avoids lingering tearing effects, keeps tearing faint, tearing lasting only one refresh cycle in random places throughtout the screen, and reduces microstutter harmoic visibility. A 125fps cap is popular in games that dont get the input lag penalty when crossing the cap boundary.

There is no one-size-fits-all rule for all games. It is very game/configuration dependent.
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