Crunch Feb 11, 2014 @ 7:53pm
Assetto Corsa - FPS / VSYNC and "micro-stutter".
I was just wondering if anyone else here was experiencing a constant "micro-stutter" when playing AC at anything other than 50 or 100fps.

If I use any other fps / v-sync combo other than 50 or 100 I get a constant micro-stutter. This is not fps (or lack of) induced stutter, nor does it have to do with graphics settings. I could be at 60 fps the entire time and everything "jitters" on screen, switch it to 100 and the stutter is gone. This issue occurs both with and without v-sync enabled.

We have gone round and round with this issue on the official forums but with no solution. Kunos does not seem to recognize this problem; however, this isn't an isolated issue as it seems to affect a certain number of people, but not all, which is the strangest part.
Showing 1-15 of 55 comments
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ThereIs0nly0ne Feb 11, 2014 @ 10:56pm 
I have this problem also. It's particularly apparent on either side of the screen when in motion.

I also get stutter / frame skipping when changing gear, only for the first few changes though.
cyclicbug Feb 11, 2014 @ 11:12pm 
Have you monitored the FPS app while testing?

I have not got a very strong machine and so have experimented a lot with settings using the app, if you use V-sync you have to be acheiving above that refresh rate to experience smooth play e.g you can get constantly above 60 fps then set refrsh to 60 and V-sync on, or getting constant 40fps or above use 30Hz with V-sync on, otherwise you get stutters when the fps drop below the refresh rate as the screen does not get refreshed for one screen draw.

The other thing to watch in the app is the processor occupancy ( red line ) to see if you are getting any spikes, I see these on mine when racing against the AI or on some parts of some tracks.

It may help if you post your specs to see if you have anything in common with anyone else having this issue. Mine runs smooth at 60hz with v_sync on at the expense of graphical settings.
Last edited by cyclicbug; Feb 11, 2014 @ 11:13pm
ThereIs0nly0ne Feb 11, 2014 @ 11:31pm 
Fair questions. I don't know about the op. It I have a GTX 680 4gb with a 2600k I7. FPS is always 60 (with a single car on track) and CPU never more than 80% used with a full grid. Fraps and EVGA precision used to monitor FPS.
Last edited by ThereIs0nly0ne; Feb 11, 2014 @ 11:32pm
mrsmr2 Feb 12, 2014 @ 2:53am 
You've no doubt checked this but is the refresh rate set to 50Hz under the display options?

Are you connecting to a monitor or a TV?
Christophoclese Feb 12, 2014 @ 7:46am 
I've had silky smooth play since day 1. I only get into trouble after adding over 11 AI on the track. *Edit - Oh, and the smoke effects can bump me down to 30fps for a short time*

660Ti at 1920x1080@60Hz, Vsync ON, frame limiter set to 63 fps, 2x AA, 0x FXAA, HDR ON. Paired with a I7-860@3.2GHz. 12Gb RAM.
Last edited by Christophoclese; Feb 12, 2014 @ 7:47am
Christophoclese Feb 12, 2014 @ 8:12am 
I experienced micro-stutter in Deus Ex: HR. Scene would be perfectly fluid until inputs were applied and the camera would move, at which point you could perceive a 'jittering' as the camera would attempt to make a smooth turn.
ThereIs0nly0ne Feb 12, 2014 @ 10:24am 
Yes, it's definitely a micro-stutter like issue. This is on a monitor refreshing at 60hz with vsync on. FPS is locked at 60. My monitor won't accept a custom refresh rate of 50hz so I can't test that out.

@BRT Cobra, I'll check the video file approach you mentioned later.
Marty Cerven Feb 12, 2014 @ 10:50am 
I dont get any micro stutter at 2560x1440 cant set 60p in game onky allows 59. If I use V sync I also set frame limit to 61 and it runs fine much smoother then v sync off which gets the micro stutters or bad tearing. Tbats with an OC titan pretty much maxed out, one thing I found is full screen rendering doesnt have triple buffering for me even if forced in drivers. If you alt+enter to go window mode then again to go back to full screen rendering it has triple buffering and is much smoother all up.

If I dont do that then any time it fets below the sync rate the fps hit is quite big and sometimes goes to half rate. Doing that before the race keeps min rates much the same as sync off and very smooth. My setup can pretty much stay above 60 most of the time but start of ai race tends to drop to 50 especially with lots of smoke or drunken AI taking eachother out sometimes. :)

Pressing alt enter confirms it goes back to full screen as I can use NV shadow play to record vis this way but if using window mode tbis wont record video. Still strange how I need to do this to make sure it stays smooth if the frame rate ever drops below sync rate even only for a couple frames.
mrsmr2 Feb 12, 2014 @ 1:32pm 
That's the opposite of what I get. If I alt-tab to desktop, v-sync gets lost and I have lots of tearing when I retun to the game. (I'm on a 7850.)
Marty Cerven Feb 12, 2014 @ 5:06pm 
Not alt tab but alt enter which is how you get back to full screen rendering in game if for some reason you left the game. I guess that after alt tabbing out if you press alt enter it should get you back to full screen mode. I cant explain why the initial full screen rendering mode is worse then after pressing alt enter as it should be the same.
Pete Feb 12, 2014 @ 5:49pm 
A lot of the technicalities of this is beyond me, but thanks for the alt/enter tip, as now if I restart the race I get my fps drop back by alt/enter. Not stutter I know, but a problem solved for me. :)
I have used alt/enter in numerous games, to get from windowed mode to full screen mode, but this is entirely different, it is reclaiming my fps drop, which I get from restarting the race.
Last edited by Pete; Feb 12, 2014 @ 7:44pm
Crunch Feb 12, 2014 @ 6:36pm 
One thing that we determined on the official forum is that there is a frame that takes longer to render than the rest.

For example, at 60 fps, frames 1,2,3,4, and 5 all have the same frame time while frame 6 takes longer to render that the rest. This was determined by doing a frame by frame analysis. Every 6th frame is out of sync with the rest and will only be in sync when rendering in multiples of 50 fps (ie 50, 100, 150 fps).

This also occurs at every other fps rates (75, 85, 120 etc) but with different degrees of micro-stutter. For example, its not nearly as noticeable at 85 fps but is still there, goes away completely at 100 fps, and returns with a vengeance at 120 fps, and lessens at 144 fps. Since I have a 144hz monitor I could test all these with v-sync enabled.
Marty Cerven Feb 12, 2014 @ 6:42pm 
For me the main advantage of alt enter is that it uses triple buffereing with v-sync without it tends to either be at 60 or half frame rate. Doing alt enter I can get any frame rate below the sync rate and its smooth where the way the game starts up on its own with a large field it may be half frame rate at the start line. Pressing alt-enter will get me to 60 or very close, also into the first corner there is a noticeable slowdown with v-sync on with AI locking up but after the alt-enter it only drops slightly below the sync rate but stys smooth.

I also cap rate as this tends to avoid any micro stutter though I dont know why, I still get very minimal with v-sync and no cap but if I cap 1 or 2 frames above the sync rate it stays pretty solid mostly.
Crunch Feb 12, 2014 @ 6:44pm 
One other thing is that the micro-stutter is completely gone during replay.
Marty Cerven Feb 12, 2014 @ 6:49pm 
I did see on the official forum that some people have issues with 60fps at 1080 but as I dont have a 60 option at 2560x1440 I havent noticed. At 59 setting my frame rate is still 59.8-60 going by afterburner stats when synced so still getting 60FPS and it looks smooth.

At first I had issues with frame smoothness and have tried all sync options and pretty much stick to v-sync on and frame cap. With it off even at over 100fps its not very smooth plus input lag is minimal for me even with the sync on with no difference in lap times or consistancy with any of the options. Having no frame cap or sync just looks stuttery and gets random tearing for me.
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Date Posted: Feb 11, 2014 @ 7:53pm
Posts: 57