Comments on: V-Sunk

By: Miracle On 34th Street

Miracle On 34th Street — Fri, 24 Feb 2012 05:55:16 +0000

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By: Remco Hitman

Remco Hitman — Sat, 14 May 2011 23:25:06 +0000

The trick is to limit the framerate to a multiple of your monitor’s refreshrate.
V-sync serverely increases input polling interval, which is what causes the lag. Running iRacing uncapped is the best way to combat input lag, but can introduce off-putting image faults when refreshrate and framerate are running very out of sync.
I’m running a 200cm projector image myself and image tearing is a huge problem on such a large image. I used v-sync for years until a freind showed me just how much input lag is introduced! Intolerable!
Make sure you install a framerate limit which is a multiple of the refreshrate, and verify that your system is able to maintain this rate most of the time.
Most screens use 60Hz nowadays, so 120fps is a good place to start.
Using 60fps would be about as bad as using v-sync! More is better in this case and, if you can, use 180fps. There is less of a chance that refresh and framerate are out of sync because at 180fps the frames last a lot shorter. I am using 180fps myself. It produces virtually no noticable tearing while, like Alison and Ray, I feel much more connected to the car.

The best of both worlds!

GLA, easy T1, antiwise rules etc etc…

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By: Luis Babboni

Luis Babboni — Wed, 21 Apr 2010 19:30:09 +0000

Even with FPSs limited at 60, the “under water” sight I ahve cause the VSync in off is simply not tolerable to me

I have an AMD Athlon X2 with 2.9 each core and an ATI 4850 of 512MB

By: Justin Weisel

Justin Weisel — Mon, 08 Mar 2010 20:39:43 +0000

I’ve never used v-sync. Not for iRacing, and not for any games or other sims I play. For this exact reason. I just feel like I have more control over the situation and my response time is better.

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Sun, 14 Feb 2010 12:02:08 +0000

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By: Szymon

Szymon — Sat, 13 Feb 2010 08:18:18 +0000

I’ve discovered that although there is no possibility to set limit above 84 fps in game menu, you can actually set it manually in .\My Documents\iRacing\renderer.ini file:
LimitFrameRate=1
DesiredFPSLimit=169
Those two lines should practically eliminate lag and make constant fps which is I believe better solution than just vsync off with variable framerate.
169 fps is the max limit fps you can set, everything above will be cut down to 169, but you can set any frame rate below, maybe 150FPS which is 2,5x of standard LCD refresh rate would be better for you so I will be thankful for your feedback.

By: Ray Bryden

Ray Bryden — Wed, 30 Dec 2009 19:22:50 +0000

Alison,

Thanks for your comments. Yes, that was exactly my experience too. I didn’t believe I had a lag problem until it was eliminated by turning off V-sync and I think that could have saved me from a lot of spins.

I have a new 5850 card now, but before I install it I am going to tinker with settings and see if I can learn a little more about what has the greatest effect on lag.

By: Alison Hine

Alison Hine — Wed, 30 Dec 2009 17:54:57 +0000

I ran with Vsync on ever since getting into the beta in June 08 because with it turned off I was getting a bizarre texture squirming that made me dizzy. The top part of the screen would be from one frame, the bottom from an earlier frame, so the whole sense motion was distorted in a very unsettling way.

Vsync cured this. I also set Frames Rendered Ahead in the nVidia Control Panel to 0 to eliminate display and controller lag.

That was with an nVidia 8800GT. Over the winter I got a 9800GTX+ OC, but I kept Vsync on and just cranked up my graphics details. Ah, full shadows! Wonderful!

But I wasn’t racing very much and when I was, I felt frustrated. In retrospect, I think this was because I never felt connected to the car; I was always reacting to things that had already happened instead of what was going on right now, and my inputs took a little time to get to the car’s physics.

Then Todd Bettenhausen convinced me to turn off Vsync. Suddenly my experience with iRacing was transformed! I felt totally connected to the car. Its responses to my inputs were instant, precise. On road courses I immediately gained a couple of seconds in lap times.

At first I was running with frame rate uncapped. Frame rate was mostly between 150 and 250 FPS. I read that this overworks the video card, so I capped the frame rate at the default 82 FPS. The immediacy went away; I felt disconnected again. So I removed the frame rate cap.

At a few corners on some tracks (Road America, for example) the frame flow got choppy and/or the screen squirming came back, so I turned off shadows. It seems that as long as the frame rate is running above 150 or so, everything is quite smooth and there’s no squirming.

I tried the steering wheel test: I turned on the on-screen wheel and got in the car. I turned my G25′s wheel back and forth rapidly. With Vsyc off, the wheel on the screen moves in perfect synchronization with the actual wheel.

Then I turned on Vsync and restarted the sim. With Vsync on, there is a very, very noticeable delay. The on-screen wheel’s motion lags the real wheel by a significant amount.

I suspect that the video card and driver have an impact on this. Perhaps some (ATI?) cards don’t exhibit the same behavior. Perhaps there are other settings in iRacing or in the video card control panel that will minimize the delay with Vsync turned on. (Todd tells me that now he is running with Vsync on, but he’s turned off AA and AF in iRacing and instead turned them on in the CP – and that this gives him very minimal lag.)

But as far as I’m concerned, based on my own experience, zero lag trumps everything else. I need that instant response to my control inputs, and I need that instant feedback through the wheel and on the screen. I don’t care if I’m overworking my video card. If it cooks itself I’ll get a new one.

No more V-sunk for me!

Alison

By: mofle

mofle — Tue, 22 Dec 2009 10:45:55 +0000

So much of this i psychological – do a double-blind test if you actually want to do a relevant test

That being said, iRacing does feel a lot different at 150fps vs. 60fps, vsynced or not – and racing games don’t really suffer from tearing in the way that e.g. shooters do.

By: W

Sat, 21 Nov 2009 07:29:10 +0000

I think you made the wrong approach to this, you should have tested on a track you are VERY familiar with and a car you are VERY familiar with. Off-course you are likely to pickup time when you continue to make laps on a track as you become more and more familiar with it.

By: peeH

peeH — Sat, 21 Nov 2009 01:24:09 +0000

They shouldn’t stop pooling the inputs and stop ticking the physics while the graphics engine wait for the v-sync. They need to better parallelise their game engine.

By: Fabrizio Cuttin

Fabrizio Cuttin — Wed, 18 Nov 2009 02:28:04 +0000

I’m really more comfortable with vsync tuned on, but I will try more extensively turning it off: I’m curious about it.