What is v sync???

[UberPooner]

Hi, so recently i posted on this forum about some mouse lagg. someone suggested that i turn off v sync. and wow, that made THE biggest difference. in hitman blood money demo, when i first playd it i had v sync on. i was geting some bad mouse lag. then just rite now i turned it of and man it made the biggest difference. soooo i was wondering what v sync actually does? and what happens when its on and when its off. here are my stats---
evga 7800gtx
and 4000+ (oc'd to 2.6)
asus a8n sli board
2g corshair xms pro ram

 

[ReDgUaRd008]

Vsync

 

[aznx]

If you don't experience tearing..then turn vsync off, if you do..well..that's your choice whether to leave vsync on or off.

 

[4keatimj]

There was a great guide on Vsync in the video forums, but it seems to have gone somewhere else now, its been a while since I've been on so I don't know where it is. If I find it I'll post a link. In the mean while...

V-Sync is (very, very basically) the process of locking the maximum frame rate to the refresh rate of your monitor. For example, if your monitor was set in Windows or the game to run at 60Hz, then with V-Sync on, a game could only run at a maximum of 60 frames per second. Increasing the refresh rate in-game or in Windows to say, 85 or even 100Hz (if your monitor supports it, note that if you have an LCD the refresh rate is probably 60Hz only) then the mouse lag issue you were having would improve dramatically. By turning V-Sync off, you are allowing the game and the video card to draw as many screens as it can per second, so the in-game lag issues would be solved somewhat.

Another complication, is that in order to match the screens refresh rate, will drop the frame rate by a factor of 2 if it goes under the limit. So if you had it set to 60Hz, as soon as it fell below it (even by a couple of frames) then it fould draw at 30FPS, then 15FPS, etc etc. I'm guessing that this is the lag issues you were having. By turning V-Sync off, you can let the game drop a few FPS and still display it at that speed, not dropping it by half. And as aznx said, if the display in-game is tearing, or distorting in any way, then leave it on. *I meant on the first time *

 

[Volucris]

And as aznx said, if the display in-game is tearing, or distorting in any way, then leave it on.

I fixed it for you.

 

[UberPooner]

thanks for the quick replys, but now im wondering what is antistrophic filtering???

 

[Volucris]

thanks for the quick replys, but now im wondering what is antistrophic filtering???

Quoted from Google Definitions:
"[size=-1]In 3D computer graphics, anisotropic filtering is a method of enhancing the image quality of textures on surfaces that are far away and steeply angled with respect to the camera. Like bilinear and trilinear filtering it eliminates aliasing effects, but introduces less blur in the process and thus preserves more detail. Anisotropic filtering is computationally relatively expensive and has only recently become a standard feature of consumer-level graphics cards."[/size]

 

[MrkXCeL]

Another complication, is that in order to match the screens refresh rate, will drop the frame rate by a factor of 2 if it goes under the limit. So if you had it set to 60Hz, as soon as it fell below it (even by a couple of frames) then it fould draw at 30FPS, then 15FPS, etc etc. I'm guessing that this is the lag issues you were having. By turning V-Sync off, you can let the game drop a few FPS and still display it at that speed, not dropping it by half. And as aznx said, if the display in-game is tearing, or distorting in any way, then leave it off.

Has this always been this way, the divide by factor of 2 ? I don't remember this happening on my old rigs, back in cs1.6 days. I would cs at 85hz 85FPS v-sync, it was perfect, and if the frames dipped, they would dip by few frames, nothing getting stuck at 42.5FPS or something. Anyhow, my new AMD x2 @ 2.5Ghz I notice a lot of games/apps at 30FPS. Especially Oblivion.

 

[Volucris]

Has this always been this way, the divide by factor of 2 ? I don't remember this happening on my old rigs, back in cs1.6 days. I would cs at 85hz 85FPS v-sync, it was perfect, and if the frames dipped, they would dip by few frames, nothing getting stuck at 42.5FPS or something. Anyhow, my new AMD x2 @ 2.5Ghz I notice a lot of games/apps at 30FPS. Especially Oblivion.

Oblivion just runs shitty most the time. I get above 60fps indoors maxed out at 1280x1024 with no aa, but outdoors it's 10-30fps.

 

[4keatimj]

I fixed it for you.

Thanks dude, its changed now to make sure it says the right thing...

Has this always been this way, the divide by factor of 2 ? I don't remember this happening on my old rigs, back in cs1.6 days. I would cs at 85hz 85FPS v-sync, it was perfect, and if the frames dipped, they would dip by few frames, nothing getting stuck at 42.5FPS or something. Anyhow, my new AMD x2 @ 2.5Ghz I notice a lot of games/apps at 30FPS. Especially Oblivion.

I've noticed that a lot of frame counters don't necessarily report the frame rate properly (as you described), they drop a couple of FPS but don't drop it dramatically. Either that, or the game/drivers implementation of V-sync isn't perfect. Either way, the drop by a factor of two is what should happen, but in reality (as we all know) thats not always the case. If you play the new games with V-Sync on, then its probable that they would sit around the 30fps mark, because of the level of detail and the speed of the video card. Again, not all frame counters are accurate so the number given may not be entirely accurate.

 

[defaultluser]

Has this always been this way, the divide by factor of 2 ? I don't remember this happening on my old rigs, back in cs1.6 days. I would cs at 85hz 85FPS v-sync, it was perfect, and if the frames dipped, they would dip by few frames, nothing getting stuck at 42.5FPS or something. Anyhow, my new AMD x2 @ 2.5Ghz I notice a lot of games/apps at 30FPS. Especially Oblivion.

Yes, it divides by a factor of two because the monitor draws a frame every 1/60th of a second, no exceptions. Iif the video card hits a particularly tough frame, and is too late with drawing it, the video card will REUSE the previous frame.

What this means is you will get intermittent 30fps bursts spaced between 60fps bursts, when your real average fps is around 60. THIS is why v-sync SUCKS.

As mentioned above, you are probably not seeing this effect because most "real-time" framerate counters actually show an average of the last 10-20 frames You see, if it showed frame-to-frame updates, it would update TOO FAST for you to see it. Even a short-term average like that can average out the 30fps spikes into something much less noticeable.

ALSO, if your hardware is powerful enough to deliver a constant > 85fps, even in the TOUGHEST sections of the game, you will NEVER see this framerate halving. The reason people don't like this is because it is wasteful - you either have to throw a lot of hardware at it to get consistent performance, or you put up with annoying inconsistent drops to 1/2 the framerate.

Sure, there are the occasional vertical tearing artifacts when you move around too fast, but you ignore them after a bit.

 

[aznx]

Yes, it divides by a factor of two because the monitor draws a frame every 1/60th of a second, no exceptions. Iif the video card hits a particularly tough frame, and is too late with drawing it, the video card will REUSE the previous frame.

What this means is you will get intermittent 30fps bursts spaced between 60fps bursts, when your real average fps is around 60. THIS is why v-sync SUCKS.

As mentioned above, you are probably not seeing this effect because most "real-time" framerate counters actually show an average of the last 10-20 frames You see, if it showed frame-to-frame updates, it would update TOO FAST for you to see it. Even a short-term average like that can average out the 30fps spikes into something much less noticeable.

ALSO, if your hardware is powerful enough to deliver a constant > 85fps, even in the TOUGHEST sections of the game, you will NEVER see this framerate halving. The reason people don't like this is because it is wasteful - you either have to throw a lot of hardware at it to get consistent performance, or you put up with annoying inconsistent drops to 1/2 the framerate.

Sure, there are the occasional vertical tearing artifacts when you move around too fast, but you ignore them after a bit.

Ignore tearing? lol..

You know if the videocard is too fast or too slow, it'll produce tearing.

 

[Tolyngee]

I kinda wish they'd implement semi-v-sync... (altho maybe this just doesn't make 100% sense for mutliple reasons, but anyway...)

If the frames being generated exceeds the refresh rate of the monitor, enable v-sync so no tearing occurs.

If below, disable it to keep the framerate higher.

I mention this as believe it or not, most of the tearing I see that bugs me is the card generating images faster than the refresh rate of the monitor, and that kind of tearing is bizarre to watch.

For example, if my monitor is 60hz, but the framerate is 300 (yup, I can give you examples), you will see multiple tears in an image.

Now, if the framerate stays that high consistently, you will see these mult tears per frame very consistently. Honestly, to the point of annoyance. (the tear points can results in multiple horiz line across your screen per every refresh...)

While it is the opposite end of the discussion here, v-sync definitely has its place if your frame is 2x+ your refresh rate.

(on a monster SLI rig, older games like HL can honestly look very AWFUL if you have v-sync off...)

Then again, the semi approach probably doesn't make sense, as whenever my framerates drop way down (in games where they are usually way way up) it's usually the CPU that's the bottleneck at that moment. Racing sism are great for this: 80+ frames consistent, v-sync is a good idea, oops, start of the race tho the fps is like 18 (yikes! that means I am getting probably a good consistent 15fps there!) cuz the CPU has to do all those damn cars at the start. (and yes it's the CPU that's the bottleneck, I went from an ATI 800XT to a 7800GTX 512MB SLI rig, with no change in the fps at the start of races...)

Which sucks cuz that's when accidents happen if you don't avoid 'em... At 15fps, sometimes it's really really difficult... Sense of speed at 15fps, eh...