Why do v-synced console games that run at 30 fps feel smoother?

I always noticed that on PC if you enable V-sync, the game will always skip some frames and be jittery if it goes under 60 fps. Even tripple buffering (forced or native to games) or the half refresh rate on the nvidia panel can't help. On a console tho, games that have v-sync at 30 fps feel alot smoother. They basically feel like 30 fps without v-sync on PC.

So I am wondering why is that.What are they doing differently? I should also note that Overlord was capped at 30 fps on PC and actually ran smooth with v-sync, but sleeping dogs for example runs like garbage on that framerate with v-sync on.(as with most games)

I am asking this because in many games I get between 50 and 60 fps and it drives me mad that they feel worse than on consoles with v-sync enabled. The only option is to disable it, but then I get the big fat tears on the screen. Some games do it better than others, but like Jeff said, Hawken was tearing like a mother fucker.

Here's an excerpt from a hardocp review of adaptive vsync

In order to understand what this technology does we must first understand what VSync is and the two options we had previously in games. Without getting into detail that will bore our readers, VSync deals with the native refresh rate of your display and how the game renders its frames. There have been, up to now, only two options for VSync in games. Either you played with VSync on or you played with VSync off. Both on or off has its pros and cons for gaming. With VSync off, your games performance (i.e. framerate) is able to exceed the native refresh rate of your display. The common refresh rate on displays is 60Hz, hence 60 FPS. There are new displays today, especially those of the 3D nature, which run at 120Hz, or 120 FPS. While these new displays are becoming more popular, we are going to focus on the more common 60Hz example.

VSync turned off sounds like a good thing, because your framerate is able to go as high as physically possible from your video card. However, there is a major drawback to allowing framerate to exceed the refresh rate of your display. The consequence is called "tearing," and it is a very real visual anomaly that you will notice more as you play your games as the framerate exceeds the refresh rate. Tearing is described as a frame literally breaking in half, or sometimes even in three parts, and part of the frame lagging behind the other part of the same frame. The result is a visually distorted image that can bother gamers. Note that tearing can technically occur if the framerate doesn't exceed the refresh rate, but it is much less likely to be noticed.

The cure to tearing is to turn VSync on. What this does is cap the game's framerates to the highest native refresh rate of your display. This means on our 60Hz display, the game won't exceed 60FPS. As most people consider 60 FPS to be a very smooth gameplay experience, this sounds like there would be no drawbacks, but unfortunately there is. The problem with turning VSync on is that the framerate is locked to multiples of 60. If the framerate drops even just a little below 60 FPS VSync will drop all the way from 60 FPS to 30 FPS. This is a huge drop in framerate, and that large change in framerate becomes noticeable to the gamer. The result is called stuttering, and when you are playing a game that consistently changes between only 30 and 60 FPS, the game speeds up and slows down and you feel this difference and it distracts from the gameplay experience. What's worse is that if the framerate drops ever so slightly below 30 FPS the next step down for VSync is 20 FPS, and then the next step down is 15 FPS.

These are large steps, with no middle-ground for framerate. With VSync turned on, while curing tearing, introduces its own problems. Therefore, up until recently there hasn't been a very good solution. Either you dealt with tearing, or you dealt with sudden FPS drops. There are some add-on logic solutions as well but these have never caught on well. NVIDIA wants to change this VSync issue, and we are glad this is finally being focused on.

That's a problem with your hardware not being able to keep a consistent 60 frames. V-sync is matching your frames to the screen's refresh rate so anytime something dips below 60 fps on a 60 hertz tv you're going to notice jittering. You don't see that problem with consoles because the games were prioritized for those consoles. Maybe play around with the graphics options in the games that give you issues because I don't have any of those issues in the games you're talking about but then again I'm getting a consistent 60 frames.

@Jams: Does it really drop all the way down to 30 frames? I have FRAPS on and in some games it drops to the 40-50 range then back to 60 but whenever it dips below 60 you notice that jitter as the framerate becomes more unstable but I never see a game drop to 30.

@Colourful_Hippie: I know its not keeping constant 60 fps, thats why I mentioned it. It runs perfectly on 60, but just a few frames lower and its jittery. I can lower settings to achieve perfect 60, but I was asking how can consoles keep the games smooth at 30 fps with v-sync on. (not as smooth as 60).

@Alexandru: I don't know the specifics but like I said before the game is optimized for the consoles. It's supposed to run a specific framerate and stay there for most of the time. I can still see the occasional jitter when a console game begins to have an inconsistent framerate. The Uncharted games are a good example of games that are designed just for the console and optimized out the ass to stay at 30 frames, that's why it looks so smooth.

Probably the fact that the games are easier to lock at 30 than at 60, so you're having a consistent frame rate and the v-syncing works well. If your frame rate is inconsistent, v-sync kinda sucks.

But that's a wild guess.

Cool, reading other responses it looks like I'm right-on. Looks like you might need some better hardware, OP.

In addition to what other people said, A lot of console games have very specifically designed motion blur to make it look as smooth as possible at 30 fps as well. Also, I don't know if you're using SLI or Crossfire or not but there are quite a few games that have issues with what's known as "micro-stuttering" if you use multiple graphics cards. Not exactly sure what causes it but I think it has to do with the way frames are rendered using two or more connected GPU's.

In console games the frames are blurred together to give the smoother appearance. This is one of the reasons why still images of console games often look worse than what think you're seeing while playing the game.

@Colourful_Hippie said:

@Jams: Does it really drop all the way down to 30 frames? I have FRAPS on and in some games it drops to the 40-50 range then back to 60 but whenever it dips below 60 you notice that jitter as the framerate becomes more unstable but I never see a game drop to 30.

It doesn't drop from 60 to 30 and it'll spew out what's been back buffered as soon as the sync signal says it's alright to 'flip'. That can be anything up to 60fps.

Also since it's a console game, there aren't any other background processes stealing flops or priority. On consoles, there's a certain amount of memory and CPU cores reserved for both the game and the persistent dashboard/XMB. On a PC, the OS and other background programs footprint changes dynamically depending on what else is running. It's more difficult to keep a pure gaming environment on PC.
 
@captain_clayman said:

In addition to what other people said, A lot of console games have very specifically designed motion blur to make it look as smooth as possible at 30 fps as well. Also, I don't know if you're using SLI or Crossfire or not but there are quite a few games that have issues with what's known as "micro-stuttering" if you use multiple graphics cards. Not exactly sure what causes it but I think it has to do with the way frames are rendered using two or more connected GPU's.

@MikkaQ: Uhm, i dont think so. I can limit the games at 30 fps with an fps limiter and they stay locked at that. It is juttery because the game skips frames to acomodate half the speed at 60 Hz. It's a known problem on PC. I just played some Assassins Creed Revelations on Xbox and its smooth at 30. i can for exanple disable v sync but still keep the framerate limited to 30 on PC and then it will run the same as on consoles. Many of the games that i try on PC have that motion blur too, it hides it a bit for sure, but it's still very noticeable.

I am using adaptive Vsync on PC, so if my games go under 60 the driver will just drop v sync instead of skipping frames, but if I get 50 fps on a game with everything maxed out, I cant just limit it to 30 and v sync it.

I guess I'm not sure what you mean exactly by "feels smoother". If the game has input logic locked to the frame update that could be part of the problem, especially if you are triple buffering.

If the game is using rigid body physics it could be an issue related to this discussion:

http://www.bulletphysics.org/Bullet/phpBB3/viewtopic.php?f=9&t=3934

essentially 30fps locked can be smoother than a varying update rate between 30 and 60 because of the physics "world" update - it has to calculate more substeps and interpolate the results. same with general game logic. If you can't count on a fixed timestep between updates you have to do some math based on the delta-time for each update and maybe calculate an additional update depending on the delta. A fixed timestep is always better. well, easier.

also, more here

http://gafferongames.com/game-physics/fix-your-timestep/

@Jams: You have just made me very unhappy about having an AMD graphics card.