The New Myth about Frames Per Second

[//[T.0.P]//]

The id engines are a bit different from most other game engines, most game engines simply re-calcuate the state of the game world at the rate you're rendering at, as soon as one frame is finished the game engine re-calculates the world states (the position of entities like enemys and in flight rockets etc) then draws the next frame

In the id engines they have a tic rate which is a fixed rate at which the game state is calculated, internally this is 60hz for games like doom 3. The frame rate is capped at 60fps because trying to render more frames would be pointless since none of the objects in the scene will have updated their positions the frame rendered would be exactly the same so you'd end up with an identical frame which is just a waste of time.

If they're considering a ticrate of 30 thats probably due to technical limitations of the platforms they're going to work with, or put another way consoles are crap and run slower

The concept would definitely change if the model animations were rendering at more than, say 60 frames? I record in-game demos, and I can see where entity updates are limited to the actual world(Or anything that is not animated). One way to tell is to look at frame by frame, or put the video in slow motion.

For instance, let's say that a character's model animation for the jump event is like a total of 120 frames. If I wanted to recorded every single frame of that jump, I would have to have the gaming running at least 120fps, and a monitor refresh @ 120Hz to capture all of those frames... Does that sound right?

 

[BinarySynapse]

Wow lots of misinformation about refresh rate and what not.


An LCD monitor does have a refresh rate, and it behaves exactly the same way it does in a CRT. The difference is in the implementation and how we experience it. A CRT has a beam that scans the screen lighting up pixels as it passes by them one at a time. An LCD has a matrix of pixels that are changed one-by-one as data comes in. They both depend on Horizontal and Vertical signals to tell the gun or control board where to manipulate the image. And they both depend on Red, Green, and Blue sub-pixel data to tell the gun or control how bright each of those pixel components at the current location should be.

This behavior is not noticeable on an LCD because the pixels are constantly illuminated via backlight rather than immediately start fading as soon as the scanning beam moves to the next pixel.


Response time is a completely new attribute of LCD and is only how long it takes a pixel to fully change after it's been told to do so. It have very little to do with refresh rate other than if that rate is too fast the pixel might not be able to respond be it's told to change again. It's sort of a CRT's pixel persistence.

So, a FPS of higher than the refresh rate of any current image display type is going to be useless. You will always see the extra frames in the form of tearing because the data is coming in pixel-by-pixel and it's changed part of the way through a screen's cycle.

 

[PrincessFrosty]

The concept would definitely change if the model animations were rendering at more than, say 60 frames? I record in-game demos, and I can see where entity updates are limited to the actual world(Or anything that is not animated). One way to tell is to look at frame by frame, or put the video in slow motion

Most engines have interpolation on things like animation, the animation itself is recorded as keyframes but the game engine can pull out any position in between those key frames.

So, a FPS of higher than the refresh rate of any current image display type is going to be useless.

I disagree that it's useless, it provides more up to date data for at least some portions of the screen, the more up to date that data the better for the player because essentially you're making a more informed decision as you move about and react to the world.

 

[Gorankar]

Anything over a minimum fps of 60 on a monitor with a refresh of 60 will give you diminishing returns graphically in typical games on a 60Hz LCD. But having a higher fps count has other side effect depending on the game. Source games time net updates with each frame up to the tick rate which is typically 66 and sometimes 100. In some games running at higher fps can alter how high you jump or how fast your guns shoots to a degree. But after a certain point it does become a moot point if you are stuck with a LCD running at 60Hz.

 

[kllrnohj]

We know the whole screen doesn't refresh at once because we still get tearing which is an effect caused when the frame being displayed to the monitor changes (the frame buffer in the video card swaps out to the next renderd frame) while the monitor is in the middle of refreshing. If the whole LCD simply refreshes at once taking only one sample from the cards frame buffer, there would be no possibility of tearing.

Except that the frame has to be sent over VGA or DVI. The LCD display itself could (and I believe does) update all at once while still having tearing due to the time it takes to send the signal.

Now the matter of more than 60fps on a 60hz screen not being visible, this is simply false and now you know that LCDs tear you'll probably be able to work out why.

Simply put the image you see on your monitor once it's finished its final refresh is not just 1 image from one frame (unless vsync is applied) but rather a collage of different frames all stitched together to provide one overall image.

You could easily argue that since a frame is one entire image, tearing results in the creation of new frames composed of multiple frames, resulting in the user still only seeing 60 FPS. Of course, if the game is running at 120 FPS and happens to line up with the monitors refresh rate so that you have no tearing, then you will only see 60 FPS.

Of course, you are talking about FPS that the card generates. Regardless of that FPS, the monitor will only ever display 60 images per second. Generating more frames than the monitor can display is pointless.

 

[BinarySynapse]

I disagree that it's useless, it provides more up to date data for at least some portions of the screen, the more up to date that data the better for the player because essentially you're making a more informed decision as you move about and react to the world.

The information that is updated would be in the bottom of the screen and wouldn't necessarily match the data in the top portion of the screen. This tends to be distracting more than helpful.

Except that the frame has to be sent over VGA or DVI. The LCD display itself could (and I believe does) update all at once while still having tearing due to the time it takes to send the signal.



You could easily argue that since a frame is one entire image, tearing results in the creation of new frames composed of multiple frames, resulting in the user still only seeing 60 FPS. Of course, if the game is running at 120 FPS and happens to line up with the monitors refresh rate so that you have no tearing, then you will only see 60 FPS.

Of course, you are talking about FPS that the card generates. Regardless of that FPS, the monitor will only ever display 60 images per second. Generating more frames than the monitor can display is pointless.

If you're sending 120FPS, you're get two frames per refresh since the framebuffer would be updated every half refresh. 90FPS would give a torn fram every other refresh, etc.

 

[archevilangel]

In terms of visually... faster than the refresh rate will always cause tearing(except when holding still)
In terms of feeling smoother... unless you're a pro twitch gamer, faster than the refresh rate is not going to help your performance much, and beyond a certain point will be beyond human perception.

 

[//[T.0.P]//]

This is starting to sound like meet the press

 

[bgd73]

I still notice nothing. I have driven post CRT to popping smoke...and no lcd is ever gonna get that far....

past 60 is more glass like, that is all.
I refer to a most common game, HL2, I started off at 45-50, now at 108. I have to run the stress test to know.
The myth is beyond fps, I am not gonna mention it.

 

[joseardzm]

It amazed me how people thinks and feels the game smoother with vsync off! it only causes tearing, are you blind??? or what?

like many around here, im convinced that higher fps than the refresh rate would not make the game smoother. If when benchmarking with vsync off the minum fps is above 60, then your game will be very fluid when vsync is on.

It is so easy to understand your screen refreshes every 1/60 of a second, how would the monitor displays more frames than what is capable of displaying!?

The real question is , do constant 120fps on a 120hz display actually makes a difference?

 

[nomu]

Except that the frame has to be sent over VGA or DVI. The LCD display itself could (and I believe does) update all at once while still having tearing due to the time it takes to send the signal.

You're very tenacious, but also wrong. Look at these. Those are photos of two LCDs displaying a stopwatch program (used to test input lag.) Each frame the program displays the time elapsed in three locations on the screen. You'll notice that the top part always starts transitioning to the next frame first, the bottom always finishes transitioning from the previous frame last, and the middle is in between.

Or perhaps you could explain why LCDs have a horizontal frequency if they update the entire screen at once.

 

[PrincessFrosty]

Except that the frame has to be sent over VGA or DVI. The LCD display itself could (and I believe does) update all at once while still having tearing due to the time it takes to send the signal.

No, the signal isn't really sent, it's an active connection it connects the frame buffer with the monitor, the whole image is active on the cable all the time until the frame buffer switchs out then instantly the whole next image is live on the cable, it's not streamed in over time or sent in bits (to my knowledge)

You could easily argue that since a frame is one entire image, tearing results in the creation of new frames composed of multiple frames, resulting in the user still only seeing 60 FPS. Of course, if the game is running at 120 FPS and happens to line up with the monitors refresh rate so that you have no tearing, then you will only see 60 FPS.

You need to be very careful here with your terminology try and differentiate between frames (what is renderd by the video card, and monitor refreshes) and a final image (one refresh). Tearing is essentially taking parts of multiple frames and stitching them together to produce one entire monitor refresh. The user is seeing 60 screen refreshes per second, each frame is made up of potentially multiple frames, not total frames but slices of frames that occured while the monitor was refreshing. You are getting more information out of just 1 entire screen refresh than you would if you had vsync on, as I said before on page 2, you can infer movement and direction of object with just 1 monitor refresh, while its still only 1 refresh it is comprised of information over a period of time rather than just 1 snapshot in time.

Of course, you are talking about FPS that the card generates. Regardless of that FPS, the monitor will only ever display 60 images per second. Generating more frames than the monitor can display is pointless.

No it's not pointless, it keeps parts of the screen more up to date than just 60fps, it gives you more recent information.

The information that is updated would be in the bottom of the screen and wouldn't necessarily match the data in the top portion of the screen. This tends to be distracting more than helpful.

Correct, it mis-aligns thats why we see a tear line, some people do find this distracting which is why vsync was invented, but many people do not find it distracting even when you're getting multiple tears each frame, when your movement is slow and steady tearing is less percievable anyway, only extreme example of movement such as mine on page 2 actually give rise to obvious tearing.

If you're sending 120FPS, you're get two frames per refresh since the framebuffer would be updated every half refresh. 90FPS would give a torn fram every other refresh, etc.

A minor error in understanding here, remember that you can and do tear with 60fps on a 60hz monitor, just because the numbers are the same doesn't mean they're in sync, so with just 60fps you're going to average 1 tear each refresh (made up of 2 frames)

It follows that a rate of 120fps would tear roughly 3 frames in one refresh. Sure if the frame is generated at exactly the same time as the monitor refresh starts then with 120fps on 60hz you'll get exactly 2 frames filling 1/2 the screen each, but that situation almost never happens, if you're out of sync most of the time the monitor is starting to refresh at the top of the screen with a frame which was probably used at the bottom of the previous refresh.

You can also tear with below 60fps without vsync on, if you're getting say 30fps then you would tear on average every other frame.

It amazed me how people thinks and feels the game smoother with vsync off! it only causes tearing, are you blind??? or what?

It feels smoother because it is smoother 1 frame is comprised of information that spans the time between the refreshes rather than just 1 static frame representing 1 snapshot in time.

It is so easy to understand your screen refreshes every 1/60 of a second, how would the monitor displays more frames than what is capable of displaying!?[/QUOTE]

It doesn't display more images per second it still displays 60 images in that time, but each image you see is parts of many different frames stitched together, see my post on page 2 with an example.

Lets get this straight you're not seeing more than 60 full images, but those images are comprised of more than 60 frames.

 

[//[T.0.P]//]

Frosty's last post was about 3 different interpretations of the logic behind monitor refreshing with and without vsync. Luckily, I believe I understood one of them

That kind of changes everything, for me anyway. Because I don't know what to think anymore, lol. If you were making a video of your game play, is it safe to say that it doesn't matter if Vsync is enabled or not? From what I understood, it wouldn't matter.

Despite LCD's refresh limitations, then why is the golden # 60?

 

[PrincessFrosty]

Vsync was designed to eliminate tearing by syncing the frame rate with the refresh of the monitor.

It has it's pros and cons, some people cannot stand tearing especially when you have a very high frame rate and the amount of tear lines on screen is getting very large like 5+ tears per refresh, alternatively some games show up tearing more, games with contrasting colours or dark/bright areas will show tearing more obviously, any vertical patterns during horizontal view point movement also show off tearing a lot.

However it has it's downsides, first of all it causes a feeling of input lag, it makes the display lag behind the mouse movements, you see on page 2 where I demonstrated at a single monitor refresh can contain parts from multiple renderd frames and the difference between them can inferm movement and direct...thats what makes your input to the mouse seem more synced with what is on screen.

Other downsides include artificial throtteling of frame rate to fix your display to 60fps, or if it cannot manage 60fps then it uses 30fps, then 20fps and so on (1/n)*(refresh rate) where n is a positive integer.

I dont know why 60hz is the golden number, it seems to be approximately the kind of frame rate you need to simulate smooth motion in digital renderings, you only need about 24fps with film but that captures motion blur, since theres no (proper) motion blur in games you need a higher rate to seem smooth.

 

[BinarySynapse]

No, the signal isn't really sent, it's an active connection it connects the frame buffer with the monitor, the whole image is active on the cable all the time until the frame buffer switchs out then instantly the whole next image is live on the cable, it's not streamed in over time or sent in bits (to my knowledge)

.

Yes, it really is streamed pixel-by-pixel. There's only three bits of data sent for every tick of the pixel clock, red, green, and blue. VGA has 5 active wires (red, green, blue, h-sync, v-sync) how is DVI has a similar setup but is digital and uses data packets to transfer image information (and audio it it's HDMI compatibile).

 

[EdZ]

Image tearing is a FRAME BUFFER artefact, not caused the the monitor. The monitor will display what the card outputs, at the rate the card outputs it, within the hardware limits of a monitor. i.e. if you try and output a 120Hz signal to an LCD that only accepts a maximum of 60Hz, the LCD will NOT exhibit tearing: it will instead display a "signal out of range" error*.

I dont know why 60hz is the golden number, it seems to be approximately the kind of frame rate you need to simulate smooth motion in digital renderings, you only need about 24fps with film but that captures motion blur, since theres no (proper) motion blur in games you need a higher rate to seem smooth.

24Hz is the threshold where the human brain starts to merge a sequence of separate images into a moving image. Above 60Hz is the point of diminishing return, where the brain can no longer gain useful extra information from additional interstitial frames. Additional visual cueing such as motion blur does have an effect on this, narrowing the range of increasing effect, as does the direction of motion (e.g. moving across the field of view vs.moving towards/away from the field view), and any stereoscopic effect.



*Exceptionally cheap and badly made monitors may not check if a signal is in range, and simply display a mess of garbage as registers roll over where they shouldn't, rather than a teared image.

 

[Neb]

24Hz is the threshold where the human brain starts to merge a sequence of separate images into a moving image. Above 60Hz is the point of diminishing return, where the brain can no longer gain useful extra information from additional interstitial frames. Additional visual cueing such as motion blur does have an effect on this, narrowing the range of increasing effect, as does the direction of motion (e.g. moving across the field of view vs.moving towards/away from the field view), and any stereoscopic effect.

Quite true, in fact the frame rate is the main contributor to the film-like quality of movies. Recent 120hz interpolating tv's change the feel of the movie by adding intermediate frames to produce a buttery smooth presentation, which some folks really hate.

From what I can tell of this thread, the general idea is that in a perfect world, assuming that a game + hardware put out a rock solid 60fps to a 60hz monitor with vsync on, there is no benefit to any additional fps.

I think this is true, but there are many different variables here that you simply can't assume. The one that matters most to me is the fact that image tearing is intolerable for me as it annoys the crap out of me. So for me, it's not an option to disable vsync unless a game is completely unplayable without it.

Image tearing happens at the frame buffer level, by the time the image is encoded to DVI it's already become bits of color, intensity, and timing signals. Of course, this is assuming you don't have a scaler or image processor in between the monitor and video card.


This page has a good overview of the some of the encoding part of the DVI spec. The article itself is also is a very good dissection of the elements involved in input-lag, along with proper testing of the signals (with a $33k oscilloscope no less!).
http://www.prad.de/en/monitore/specials/inputlag/inputlag-part3.html#Digital

 

[PrincessFrosty]

Image tearing is a FRAME BUFFER artefact, not caused the the monitor. The monitor will display what the card outputs, at the rate the card outputs it, within the hardware limits of a monitor. i.e. if you try and output a 120Hz signal to an LCD that only accepts a maximum of 60Hz, the LCD will NOT exhibit tearing: it will instead display a "signal out of range" error*.

24Hz is the threshold where the human brain starts to merge a sequence of separate images into a moving image. Above 60Hz is the point of diminishing return, where the brain can no longer gain useful extra information from additional interstitial frames. Additional visual cueing such as motion blur does have an effect on this, narrowing the range of increasing effect, as does the direction of motion (e.g. moving across the field of view vs.moving towards/away from the field view), and any stereoscopic effect.

24Hz is the threshold for film which is shot with a camera with a long exposure time. It captures light from a period of time rather than an instant snaphot, if an object is moving fast in the view then it comes out as a blur. When playing back at 24fps the bluring effect is enough to trick or brains into smooth motion.

Renderd images do not naturally produce motion blur so you need a greater number of them to produce an apparantly smooth image, quite a lot more in fact. Other factors such as rate of change of the scene also effect what sort of frame rate is appropriate, what makes us even more sensitive to this is the fact that we play games which take our input and give us feedback based on that, and we're more sensitive when we're getting visual feedback which is compared to our input rather than just passively watching something occuring on screen we have no control over.

This website is very good at exploring the concept of fluid motion:

http://www.100fps.com/how_many_frames_can_humans_see.htm

Make specific note of the TV video clip captured at 25fps but with no motion blur, it looks really crap, without motion blur 60hz is pretty much acceptable for most circumstances but fast moving objects will still appear to leap large distances across the screen, so there is use for frame/refresh rates higher than 60hz, but you're right it's a case of diminishing returns at that point.

Image tearing happens at the frame buffer level, by the time the image is encoded to DVI it's already become bits of color, intensity, and timing signals. Of course, this is assuming you don't have a scaler or image processor in between the monitor and video card.

I don't think thats correct. The frame buffer is swapped almost instantly by the video card, the tear happens because the data the monitor is using to write to the screen is changed while it's partially through drawing it to the screen.

 

[phide]

But is it smoother ONLY because a card that delivers a 120FPS avg is probably able to keep the minimum over 60fps ? That is the question...

And that is the answer

The real question is , do constant 120fps on a 120hz display actually makes a difference?

You'll perceive the motion somewhat differently than you would if you were locked at 60 Hz, yes. 60 Hz isn't the absolute top end, just a good top end for fluid display of motion without motion blur. In my experience, anything past 75 to 80 Hz isn't perceivable.

The game may still play somewhat different depending on whether the engine uses a fixed tic rate for input and movement simulation, but that's an entirely different debate.

 

[PrincessFrosty]

I recently swapped out my 30" LCD for my old Iiyama 19" CRT, ran the original L4D at 1042x768 at something daft like 200Hz with a really high frame rate and the smoothness difference between that and 60hz is very significant it effects how accurately you can aim and how fast you can respond to things.

One thing is for sure higher refresh rates for gamers is beneficial, you just need to play it to appreciate it.

 

[kllrnohj]

You're very tenacious, but also wrong. Look at these. Those are photos of two LCDs displaying a stopwatch program (used to test input lag.) Each frame the program displays the time elapsed in three locations on the screen. You'll notice that the top part always starts transitioning to the next frame first, the bottom always finishes transitioning from the previous frame last, and the middle is in between.

Or perhaps you could explain why LCDs have a horizontal frequency if they update the entire screen at once.

I could very well be wrong, but those images don't prove or disprove anything. It takes time to send the screen image across the cable, that was my point. It gets sent the same way CRTs used to draw. Thus if it is half way through sending the image when the buffers get swapped - guess what? You just tore the frame, irrespective of how the monitor displays the resulting image.

No, the signal isn't really sent, it's an active connection it connects the frame buffer with the monitor, the whole image is active on the cable all the time until the frame buffer switchs out then instantly the whole next image is live on the cable, it's not streamed in over time or sent in bits (to my knowledge)

What? You can't store data on a cable, that doesn't make any sense. There is a fixed amount of bandwidth that DVI can provide (hence why they added dual link, and now display port). Anyway, having looked it up, DVI sends either 1 or 2 pixels per clock (single- or dual-link, respectively).

You are getting more information out of just 1 entire screen refresh than you would if you had vsync on, as I said before on page 2, you can infer movement and direction of object with just 1 monitor refresh, while its still only 1 refresh it is comprised of information over a period of time rather than just 1 snapshot in time.

I would love to meet the person that could think quickly and clearly enough to analyze 1/60th of a second, deduce that the bottom of the screen was more updated than the top, and then make a decision based off of that information. BUT, our brains simply can't react that fast while being that analytical. Meaning only 2 scenarios will happen. Either A) The person ends up focusing on the tear and gets frustrated/annoyed, or B) the person is capable of ignoring the tear and the images appears as 1 frame to them that is interpreted as a single point in time (not multiple).

No it's not pointless, it keeps parts of the screen more up to date than just 60fps, it gives you more recent information.

It is useless because that "more recent information" won't be picked up by our brains as such, and it takes far longer than even 1/60th of a second to actually make a decision as opposed to simply a reaction. Keep in mind the speed we are talking here. You keep implying that people can actually see and make decisions based off of a single frame, that just isn't true. Hell, if you blink you'll miss 6 frames. That is the update speed we are talking about here.

 

[Hulk]

How about if your flat widescreen monitor has a refresh rate of only 60Hz, how can it display more than 60FPS when it only refreshes at 60? With a CRT monitor it would make sense because you can adjust the refresh rate.

 

[PrincessFrosty]

I could very well be wrong, but those images don't prove or disprove anything. It takes time to send the screen image across the cable, that was my point. It gets sent the same way CRTs used to draw. Thus if it is half way through sending the image when the buffers get swapped - guess what? You just tore the frame, irrespective of how the monitor displays the resulting image.

I don't know enough about the way the data is sent over the cable to really speak anymore in depth about this specific point, I will however look into it and see what I can find.

I'm fairly sure that what you saying wrong, the effect that occurs is you get X many pixel rows of one frame and then Y many rows of the next frame, Z many rows of the next frame etc

If it worked like you say then not only would the frames be out of sync with each other but also the relative position of where each row of pixels would be wrong, it's complicated to explain but if you think about what you're saying you'll get it.

I would love to meet the person that could think quickly and clearly enough to analyze 1/60th of a second, deduce that the bottom of the screen was more updated than the top, and then make a decision based off of that information. BUT, our brains simply can't react that fast while being that analytical. Meaning only 2 scenarios will happen. Either A) The person ends up focusing on the tear and gets frustrated/annoyed, or B) the person is capable of ignoring the tear and the images appears as 1 frame to them that is interpreted as a single point in time (not multiple).

Perception doesn't work like that, we dont analyse each frame, our brain automatically interperates and we see smooth motion, with vsync on the whole screen is universally old, with vsync off the top part is old and the tears down the frame are newer. Higher frame rates seem smoother because there is not only movement between screen refreshes but one frame can contain information of motion, its like a form of interpolation, we're geting snippets of information of whats going on at several points in time in that drawn image

It is useless because that "more recent information" won't be picked up by our brains as such, and it takes far longer than even 1/60th of a second to actually make a decision as opposed to simply a reaction. Keep in mind the speed we are talking here. You keep implying that people can actually see and make decisions based off of a single frame, that just isn't true. Hell, if you blink you'll miss 6 frames. That is the update speed we are talking about here.

It is picked up by your brain, I did not mean to imply that you can study a single refresh during normal refresh speeds, it should be obvious that's not what I was saying. I was analysing one frame in my example to prove a point, that one monitor refresh can contain more information than is held in just one renderd frame, not necessicarily more pixels but more about what is happening in the game world.

We perceive 24fps TV captured with motion blur as smooth but we percieve 24fps TV without any motion blur as choppy, obviously at the same resolution you have the same amount of pixel data on each refresh of the TV screen, yet with motion blur you're seeing movement within one single frame and that helps increase the perception of smooth motion.

Hope that clears up any misunderstandings.

 

[MrGuvernment]

What are you talking about? While LCDs don't have a scanning electron beam, refresh rate is still relevant if for no other reason than their connections work the same way. Data is transmitted in a fashion such that the whole screen is refreshed a number of times per second. It isn't a differential setup where only things that change are sent.

Now one of the upshots of this is that it is only sent out so often from the card to the screen. As such you can have a card render as fast as you like, the frames won't get displayed. The card will only send 60 frames per second to the monitor.

LCD "refresh" on a per pixel basis, not the entire screen, so each pixel can refresh / change at 60mhz / 120mhz so to speak.

 

[g1xx3r]

60 fps solid..Im good.

 

[BinarySynapse]

LCD "refresh" on a per pixel basis, not the entire screen, so each pixel can refresh / change at 60mhz / 120mhz so to speak.

Hz, not MHz.

 

[nomu]

I could very well be wrong, but those images don't prove or disprove anything. It takes time to send the screen image across the cable, that was my point. It gets sent the same way CRTs used to draw. Thus if it is half way through sending the image when the buffers get swapped - guess what? You just tore the frame, irrespective of how the monitor displays the resulting image.

You weren't looking at the right effect. There is no tearing in those images, both monitors are running off of OSX with Vsync enabled.

The timer displaying two times at once is not a torn frame, that's a result of the response time of the LCD. When the monitor is told to display a different image, it takes time for black pixels to turn white and white pixels to turn black. When they're not finished changing, the old frame that just got refreshed over shows up as a ghost under the new frame that the LCD is transitioning to.

You'll notice that the bottom of the LCD is always behind the middle and top in transitioning to the next frame (and the middle is behind the top.) That's because the monitor refreshes each line of pixels from left to right, and top to bottom.

 

[Putz]

Hmm

silly analogy here but if my tires are spinning on the ice and my speedo reads 100kph but the car is in fact moving 60 kph, therefor my car reporting 100kph but moving at 60kph is faster than yours at 60 kph

lol

running more fps than the lcd can handle just makes for tearing imo, i have yet to see a game that doesn't look better with vsync on, providing the card doesn't struggle to hold 60 fps

 

[Deleted member 201992]

So many idiots in this thread. The human eye can detect far more than 60fps.

 

[Deleted member 201992]

It amazed me how people thinks and feels the game smoother with vsync off! it only causes tearing, are you blind??? or what?

like many around here, im convinced that higher fps than the refresh rate would not make the game smoother. If when benchmarking with vsync off the minum fps is above 60, then your game will be very fluid when vsync is on.

It is so easy to understand your screen refreshes every 1/60 of a second, how would the monitor displays more frames than what is capable of displaying!?

The real question is , do constant 120fps on a 120hz display actually makes a difference?

I own a samsung 2233rz and the 120hz native support blows away my 30" samsung that I just sold for fps games like quake, and counter-strike.

 

[BinarySynapse]

So many idiots in this thread. The human eye can detect far more than 60fps.

It's not about how many FPS that can be deteted. It's about how many frames can be displayed by monitors that are limited to 60Hz, to which the answer is "parts of all of them" Now the question is, does seeing parts of 2 to 4 different frames on the same refresh cycle benefit the user? Some think it's a distraction, while others swear it contributes to the fluidity of the game.

 

[akotlar]

Do I need to fetch the LOL WUT picture again?

How do you figure that a higher FPS than refresh rate does anything? You realize that the refresh rate is the rate that the panel displays frames. As such I fail to see how having a higher rate does anything, if your card puts a new screen for display, and then changes to yet another before the monitor is ready, well that intermediate frame is lost, never displayed.

So what is it you think having a higher FPS than refresh gets you?

Not nec. Try playing at 65fps on a 60hz monitor, then go up to 120. Big difference. The reason being that fractional rates are poorly displayed. It gives a stuttering reminiscent of 3:2 pulldown.

 

[akotlar]

No, not really. Cards don't render to the display buffer, they render to a back buffer then swap when they are ready to display a frame. All you'll achieve with vsync off is, well, tearing. Doesn't matter how fast your card is going, you still get only 60fps on the monitor and you'll just have image tearing, which is quite visible to many people.

Better to just lock it to the refresh and have a very solid display.

With Vsync on, the graphic card is syncing to the last rendered frame. If the last frame was rendered at any value below the target refresh, the displayed frame is rendered at refresh/2, since the card wants to render in discrete steps of 1/N, where N is some integer (ends up being 30 fps for a refresh of 60 and a framerate 30-59 fps, 20 fps for 20-29 fps). You always introduce an extra frame of latency as you will be comparing your result with the previous frame. So yes, there is an increase in latency. If you want to keep your framerate steady in <refresh frames, you'll need to a third buffer. So then you'll have 4 frame delay, or 2 extra frames. It can certainly become noticeable in a 60fps game.

 

[MrGuvernment]

^^ is that why they say use triple buffering when you have vsync on?

my LCD's don't tear that i have seen, i know some can really bad... and i have it off, i find that with Vsync on i get much much lower MIN FPS on games.

 

[nomu]

If you want to keep your framerate steady in <refresh frames, you'll need to a third buffer. So then you'll have 4 frame delay, or 2 extra frames. It can certainly become noticeable in a 60fps game.

You need a third buffer, but it doesn't have to increase delay unless you intentionally make it that way. You're talking about render ahead, which would be better described as "display behind." That is one form of rendering that is commonly referred to as "triple buffering" when it probably should not be.

Triple buffering allows the video card to render at FPS beyond the refresh rate of the monitor without any tearing.

 

[kllrnohj]

You weren't looking at the right effect. There is no tearing in those images, both monitors are running off of OSX with Vsync enabled.

The timer displaying two times at once is not a torn frame, that's a result of the response time of the LCD. When the monitor is told to display a different image, it takes time for black pixels to turn white and white pixels to turn black. When they're not finished changing, the old frame that just got refreshed over shows up as a ghost under the new frame that the LCD is transitioning to.

You'll notice that the bottom of the LCD is always behind the middle and top in transitioning to the next frame (and the middle is behind the top.) That's because the monitor refreshes each line of pixels from left to right, and top to bottom.

Ah, I see it now.

I don't know enough about the way the data is sent over the cable to really speak anymore in depth about this specific point, I will however look into it and see what I can find.

I'm fairly sure that what you saying wrong, the effect that occurs is you get X many pixel rows of one frame and then Y many rows of the next frame, Z many rows of the next frame etc

If it worked like you say then not only would the frames be out of sync with each other but also the relative position of where each row of pixels would be wrong, it's complicated to explain but if you think about what you're saying you'll get it.

What? The position wouldn't be out of sync at all. When the frame buffers are swapped the system doesn't begin resending the data, it continues from where it was. So if it had sent up 100,000 pixels, it would continue sending at 100,001. Just now the data in the buffer is that of a different frame.

Perception doesn't work like that, we dont analyse each frame, our brain automatically interperates and we see smooth motion, with vsync on the whole screen is universally old, with vsync off the top part is old and the tears down the frame are newer. Higher frame rates seem smoother because there is not only movement between screen refreshes but one frame can contain information of motion, its like a form of interpolation, we're geting snippets of information of whats going on at several points in time in that drawn image

But you don't get a higher FPS with VSYNC off. You still only get 60 images per second, period. On an LCD with a refresh of 60hz, it doesn't matter if you are getting 60FPS or 100000FPS the resulting motion will be equally smooth because your eyes will only ever get 60 images. It doesn't matter if the image is made up of 1 frame or 100 frames, we still perceive it as a singular image.

It is picked up by your brain, I did not mean to imply that you can study a single refresh during normal refresh speeds, it should be obvious that's not what I was saying. I was analysing one frame in my example to prove a point, that one monitor refresh can contain more information than is held in just one renderd frame, not necessicarily more pixels but more about what is happening in the game world.

But you aren't getting more of anything. There is no more. There is a fixed number of pixels. It doesn't matter *at all* if the bottom of the screen is ever so slightly newer than the top, you simply won't perceive it as such.

We perceive 24fps TV captured with motion blur as smooth but we percieve 24fps TV without any motion blur as choppy, obviously at the same resolution you have the same amount of pixel data on each refresh of the TV screen, yet with motion blur you're seeing movement within one single frame and that helps increase the perception of smooth motion.

Were did motion blur come into play? Tearing is not a form of motion blur...