WHAT IS V-SYNC?

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Crysis-Online

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First of all, sorry about the caps, but I really want to clear this up. I read a lot about Vsync and most of the time, people don't know what they're talking about. So let me explain what it is. Just to prevent confusion, I'll be referring to CRT monitors. LCD's are similiar but don't refresh from left-right, top-bottom like CRT's do.


Chapter 1: What Is V-Sync (Vertical Synchronization), And What Does It Do?

V-Sync obviously involves syncing, but what does it sync? Monitors have what we call "refresh rates". The refresh rate of a monitor is measured in hertz, each hertz is equal to one full refresh. Graphics cards also have a 'refresh rate', but that is referred to as a frame rate. The frame rate of a graphics card varies constantly depending on what it is rendering.

At times, the graphics card will send the monitor a new frame before the monitor has finished drawing the next frame. So, what happens then is the monitor start drawing the new frame from where it was currently drawing the previous frame. This creates what we call 'tearing' as it looks like the image has been torn. This is why V-Sync was (I guess you could say) invented.

V-Sync tells the graphics card to what until the frame has finished being drawn. To do this, the graphics card needs to wait for the next 1/60th of a second block (if you were using a refresh rate of 60hertz). This makes sure the graphics card outputs at the same rate as your monitor. The frame waiting to be sent gets stored in the graphics cards buffer until it is sent to the monitor.

That's pretty much how it works...

Chapter 2: Does V-Sync Limit The Frame Rate?

Well yes and no, preferrably no. If your monitor can only refresh 60 times a second, then it can only show 60 frames per second; even if the graphics card is outputting at 200 frames per second (fps). So, vsync doesn't actually limit the displayed frame rate. This is the common mistake people make. They think that V-Sync will reduce their fps.

But seeing how the graphics card has to wait until the next multiple of 16.6 (1000ms / 60), there will be an unnoticable delay. But if there wasn't a delay, you would only see part of the next frame if it is sent while the monitor is drawing the previous frame.

Chapter 3: Should I Use V-Sync?

YES, you should. Why not? You get rid of that annoying tearing (which becomes even more naticable at lower frame rates). I'm not sure why anyone wouldn't enable V-Sync. The myth that it reduces the frame rate was just a misunderstanding I guess you could say.


Anyway, hopefully people will stop spreading that incorrect rumour about Vsync reducing your frame rate.

Happy Gaming... and enable V-Sync via your graphics card driver so it is always on.

 
Your chapter 2 is partially wrong.
Vsync DOES cause massive fps drops when the game is running at a fps value LESS than the monitors refresh rate. (unless there is some sort of triple buffering being used)

For example, if your monitor refreshes @ 60, but the game runs at 59fps, with vsync on you will only get about 30FPS. (it can vary depending on the game / engine). The workaround for this is triple buffering. Which does not work 100% properly DirectX yet, and is not 100% compatible with all games.

I disagree with your chapter 3 also.
Firstly, imo you should only enable Vsync if you cannot stand the tearing in a game, depending on the game / engine there may be minimal (or negligible / unnoticeable) tearing even with vsync off, in cases such as this dont enable vsync.

Secondly, in extremely fast paced multiplayer games, or multiplayer games where your reaction time to the hundredth of a second makes can mean living or dying, the fraction of a second during which the buffer holds the frame before sending it to the monitor puts you at a disadvantage. Most average players will not notice it, but pros and hardcores apparently do, as some of them have mentioned it.

Happy Gaming... and enable V-Sync via your graphics card driver so it is always on.
Click to expand...
IMO players should leave it on application preference, then set it within the game/app itself.

You're talking about vsync as if it were some holy grail of gaming - but the truth is its just a workaround to a possibly annoying issue - and vsync itself is not trouble free, and is not a perfect ideal solution in every scenario.
 
Well I've been playing CS:S for years, I just realized vsync was on today, I would normally max my FPS out at 75fps(on my 75hz monitor) well I turned it off and increased my resolution, low and behold I get 115fps


Personally, FORGET VSYNC
 
Well the problem with not using Vsync is that digital devices are mostly fixed a 60hz, so you get very bad tearing which can cause severe eyestrain. It seems to be a huge issue in games like Doom 3 and FEAR, where there are a lot of dark environments and flickering lights, but not so much of an issue with Battlefield 2.
 
As a long-time gamer, not to mention an electrical engineer, I'd like to add this:

Tearing is a vertical artifact caused by the way the frame is drawn to the screen (left-to-right scan, top-to bottom). If the frame changes between two horizontal scan lines, the result is a "tear," which is simply the boundary between two different frames.

NOTEABLE tearing artifacts are typically only caused by objects in the game with STRONG vertical lines and/or high contrast effects. For example, back when I used to play GL Quake on my Rendition card, I got ugly tearing artifacts all the time because the framerate was far below that of my monitor's refresh (85 Hz). The more rounded, layered, shaded and detailed objects of modern games tend to hide the effects of tearing. For example, I play Oblivion with vsync off and get fairly low framerates outdoors, but the exceptional layers (low contrast foliage blends well) and effects combined with the lack of pure vertical edges means you rarely notice tearing.

The severity of tearing artifacts are directly related to how fast you move within a game engine. If your movement speed is constrained, then the maximum size of any tearing artifacts is reduced.

Tearing severity is also typically only noticeable at lower framerates, because when the framerate is high the frames are updated so fast that you have very little camera movement between frames. However, at lower framerates, V-sync also becomes incredibly annoying because it is constantly altering between (for 85Hz) 42.5 and 28.3 fps, producing jerky gameplay. When playing with v-sync disabled, even lower framerates feel smooth because they are CONSISTENT.

And yes, I play with v-sync disabled. You'll note that I TRIED playing with it disabled for some time, especially after I got Half-Life (1). Half-Life had terrible tearing because the engine brought video cards to their knees, and most maps were FULL of vertical edges like doorways and crates. I found that the jerky performance with v-sync disabled wasn't worth it, and I found that the extra memory required for triple-buffering was killing my tiny texture memory. Even to this day, things really havn't changed: if you want triple-buffering, you'll likely have to reduce or disable some other memory-hungry feature, like HDR or AA or AF.
 
Why not use it?

Silly question really...if your video hardware cannot render 60 FPS or above (make that 75FPS for a lot of CRT monitor users) then the video card starts taking longer than 1 whole refresh to produce the next frame, so the previously rendered frame is used again for a 2nd time, which effectivly halfs the frame rate appearing on the monitor, with your 60FPS example you can expect to see frame rates of 30FPS and probably at times 15 FPS

Most people aim for an average frame rate of at least X Y or Z but thats an average, your minimum frame rate is whats important here and even with an average of 60 FPS you're still likely to see min frame rates in the 20-30 range which is going to force the monitor down to only rendering 15 different frames a second.

I personally don't notice tearing when the frame rate is roughly that of the refresh rate, only when it's in the magnitude of 2-3 times larger (i.e 120FPS +) do I really start to notice it, and thats because the image starts to tear multiple times in one refresh. Generally speaking you'll only ever see that on old games, new games most people "spend" there video rendering power on making the game look as nice as possible.

If you're one of the unlucky ones who can easily see tearing and get annoyed by it then expect to be running at 100FPS before you maintain a 60FPS min value.
 
MrBojangels said:
Well I've been playing CS:S for years, I just realized vsync was on today, I would normally max my FPS out at 75fps(on my 75hz monitor) well I turned it off and increased my resolution, low and behold I get 115fps


Personally, FORGET VSYNC
Click to expand...

You weren't seeing 115fps mate. Your graphics card was rendering that many frames, but you were still seeing 75fps. That's the common mistake people make. It's also the main reason why I made this topic.


Drexion said:
Secondly, in extremely fast paced multiplayer games, or multiplayer games where your reaction time to the hundredth of a second makes can mean living or dying, the fraction of a second during which the buffer holds the frame before sending it to the monitor puts you at a disadvantage. Most average players will not notice it, but pros and hardcores apparently do, as some of them have mentioned it.
Click to expand...

And so instead they'll see half a frame which I'm sure is very helpful. I think that would be a greater disadvantage than a 1/60th - 1/80th of a second wait.


Drexion said:
For example, if your monitor refreshes @ 60, but the game runs at 59fps, with vsync on you will only get about 30FPS. (it can vary depending on the game / engine). The workaround for this is triple buffering. Which does not work 100% properly DirectX yet, and is not 100% compatible with all games.
Click to expand...

I play with Vsync on all the time and have never noticed huge fps fluctuations from 75fps to 37fps? I'd like to see where you read/heard that. I've never heard of that before but some of the lower posts suggest the same thing.

I agree that you may not notice tearing at 75fps, but you do when say 10 frames in a row have all be ripped roughly at the same point. I hate that, totally ruins the games immersion for me. I'm a video man, so I've always like perfect motion.etc I would rather 30 consistant, evenly spaced frames than 40 which are all over the shop. Self preference I guess. But like I said, I enjoy the cinematic experience which doesn't include frame tearing.
 
Frosteh said:
Most people aim for an average frame rate of at least X Y or Z but thats an average, your minimum frame rate is whats important here and even with an average of 60 FPS you're still likely to see min frame rates in the 20-30 range which is going to force the monitor down to only rendering 15 different frames a second.
Click to expand...

I agree with everything in your post except this. With sync enabled, frames are drawn at ANY whole number of frames, not just powers of 2.

You'll see the following framerate ratios with vsync enabled:

1 / 1 60fps
1 / 2 30fps
1 / 3 20fps
1 / 4 15fps
1 / 5 12fps

So, as your framerate gets lower, the jerkyness is less apparent because the steps between framerates is smaller. However, this is not such a good thing because the much sought-after framerate range of 30-60fps only has TWO steps: 30 and 60. This makes for rough, jerky gaming as the framerate jumps back and forth between 30 and 60fps several times a second, and may even jump to 20fps for short periods of high load.
 
Crysis-Online said:
I agree that you may not notice tearing at 75fps, but you do when say 10 frames in a row have all be ripped roughly at the same point. I hate that, totally ruins the games immersion for me. I'm a video man, so I've always like perfect motion.etc I would rather 30 consistant, evenly spaced frames than 40 which are all over the shop. Self preference I guess. But like I said, I enjoy the cinematic experience which doesn't include frame tearing.
Click to expand...

It does depend on the person. I enjoy smooth movements above all else, mainly because I used to play a lot of FPSes. You come to notice the laggy gameplay produced by vsync in fast-action games, especially when turning. Because of the wide variation in processing power required for each frame as you make the turn, you're going to see the framerate jerk "randomly" between (possibly 20) 30 and 60 fps.

This creates an ugly feel when you're moving the camera, and is the chief reason I don't use vsync. Even in slower-paced games, I crave the fluid movement you get without vsync on.

When you turn the sync off, it's as if you're filtering the output (much like you can build an electrical filter to exclude high frequency) such that you remove the extreme framerate changes of 60 fps and 30 fps and replace them with a more regular 40-50fps.
 
defaultluser said:
I agree with everything in your post except this. With sync enabled, frames are drawn at ANY whole number of frames, not just powers of 2.

You'll see the following framerate ratios with vsync enabled:

1 / 1 60fps
1 / 2 30fps
1 / 3 20fps
1 / 4 15fps
1 / 5 12fps

So, as your framerate gets lower, the jerkyness is less apparent because the steps between framerates is smaller. However, this is not such a good thing because the much sought-after framerate range of 30-60fps only has TWO steps: 30 and 60. This makes for rough, jerky gaming as the framerate jumps back and forth between 30 and 60fps several times a second, and may even jump to 20fps for short periods of high load.
Click to expand...

yeah thats right, sorry not thinking straight, it's 3am :)
 
Crysis-Online said:
You weren't seeing 115fps mate. Your graphics card was rendering that many frames, but you were still seeing 75fps. That's the common mistake people make. It's also the main reason why I made this topic.
Click to expand...
I know that, but its better then getting under 40fps or under 30fps when it goes under 75fps, thats why i leave vsync off, it robs me of my framerate and tearing is so uncommon/hard to notice at high FPS its a non issue for me

The source engine gets very jerky under 60fps, I cant have that
 
Crysis-Online said:
Chapter 3: Should I Use V-Sync?[/SIZE]

YES, you should. Why not? You get rid of that annoying tearing (which becomes even more naticable at lower frame rates). I'm not sure why anyone wouldn't enable V-Sync. The myth that it reduces the frame rate was just a misunderstanding I guess you could say.
Click to expand...

I strongly disagree. You should only use vsync if "tearing" is noticable and bothersome. Otherwise, keep it off, because VSYNC DOES REDUCE FRAMERATE (as others have mentioned).
 
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