Why was Vsync needed?

I'm not trying to start another fps thread, just a question on Vsync.

I 'm forcing Vsync in the Nvidia setup menu and it seemed to get rid of the "tearing" I would get in the game menus and during flight. But it makes no sense why it would help. I'm using a plasma tv for a monitor with a 600 hz refresh rate, my in-flight fps are ~ 60 fps. There's no way the FPS is exceeding the refresh rate of the monitor which is listed as the reason for forcing Vsync in http://www.tweakguides.com/NVFORCE_6.html . Right?

Hey Woots,

I have the idea that the 600 Hz is not the frequency at which the pictures are transmitted to your monitor, but rather the internal monitor pixel update rate. This is not the figure you should be looking at when determining whether VSync would be helpful.

Rather the following applies when VSync is disabled:

The videocard has a frame buffer which is filled by the GPU at the best frequency A it can produce pictures at. At the same time and independently of A, the output is read at a constant frequency B from the same buffer and sent to the monitor. A generally varies with scene complexity and is what is shown when displaying the frame rate in-game. B is what you set in the monitor properties of your display driver.

Now comes the trick: it takes a bit of time to transmit a frame to the monitor and when during this time a new frame is loaded into the buffer, your screen will be built up partly from frame x and partly from frame x + 1. That's the tearing you see. VSync synchronises A to only update the frame buffer after a frame has been sent to the monitor.

At least that's how I understand it. This doesn't explain why VSync would not be necessary when B is very high. If that's the case, one would expect the chance that the buffer is updated while read to increase. Any ideas?

Wow, I ask for coffee and you whip out this gourmet sh*t on my a$$.

Anyone know the movie that's from?

Thanks for the reply. Nothing is as straight forward as it seems.

lololol ^^

 

Rather the following applies when VSync is disabled:

The videocard has a frame buffer which is filled by the GPU at the best frequency A it can produce pictures at. At the same time and independently of A, the output is read at a constant frequency B from the same buffer and sent to the monitor. A generally varies with scene complexity and is what is shown when displaying the frame rate in-game. B is what you set in the monitor properties of your display driver.

 

Now comes the trick: it takes a bit of time to transmit a frame to the monitor and when during this time a new frame is loaded into the buffer, your screen will be built up partly from frame x and partly from frame x + 1. That's the tearing you see. VSync synchronises A to only update the frame buffer after a frame has been sent to the monitor.

 

Wow, I ask for coffee and you whip out this gourmet sh*t on my a$$.

 

Anyone know the movie that's from?

 

Thanks for the reply. Nothing is as straight forward as it seems.

Well that would be Pulp Fiction of course! Tarantino is always good for great quotes.

Yeah sorry for being a smartass:smartass:, but that's how it works. Let's top it off then shall we? ;)

I think without VSync you will always have tearing artifacts. What you may have confused with VSync is the triple buffer. This relates to VSync in that it eliminates drops in frame rate and increases in latency due to VSync if the frame rate is lower than the refresh rate (A < B).

Yeah sorry for being a smartass:smartass:, but that's how it works. Let's top it off then shall we? ;)

You misunderstand. I was complimenting your reply.

Oh I got that, thanks. The smartass part was more like a reply to Viper's LOL WUT comment...

I'm reading now that plasma aren't really 600 hz. They're 60 Hz but drawn 10 times/sec in "sub fields". End effect is supposed to be smoother motion. So yes, the need for Vsync is understandable now.

Why was Vsync needed

There are a number of reasons to want to post. More than 10. This cant really be a poll.

Every aspect of 3D settings is described and illustrated here

http://www.nhancer.com/?dat=d_start

Why? / Advantages

1. Enabling Vsync prevents image tearing

The image tearing is mostly noticable during high rate of turn in a hover, fast horizontal camera panning or observing a target on your 3/9 o'clock while passing by fast (target identification is almost imposible in such conditions).

2. With Vsync enabled 3D application works on constant (fixed) FPS, as hardware performance allows. See the Disadvantages for more details. Fixed FPS prevents stuttering and makes movement more smooth.

Disadvantages

Only FPS equal to 1/1, 1/2, 1/3, 1/4, 1/5 etc. of monitor refresh rate is possible e.g. in case of 60 Hz monitor refresh rates 60fps, 30fps, 20fps, 15fps, 12fps are available.

Solution1:

Force triple buffer but this works only in OpenGL games. For DirectX there is a tool called D3D Overrider‎ but it rarely works. I tried it for BS and it didn't. You can also try http://www.nvnews.net/vbulletin/showthread.php?t=60591

Solution2:

Pick refresh rate which will give you 1/1, 1/2 or 1/3 of monitor refresh rate closer to your target FPS. You can do a simple spreadsheet with three graphs to assist you. Not much room for maneuvers here, as you can see...

Where can i fix the FPS? Some .lua file that needs editing??

Edit ...\Config\Graphics.cfg and go to line 389 (maxfps=0; by default)

So with a 60 hz monitor with Vsync enabled

- all in-game fps > 60 would be limited to 60 fps.

- all in-game fps > 30 but < 60 would be limited to 30 fps

That sux, man. Thanks Bucic for the help.

So with a 60 hz monitor with Vsync enabled

- all in-game fps > 60 would be limited to 60 fps.

- all in-game fps > 30 but < 60 would be limited to 30 fps

 

That sux, man. Thanks Bucic for the help.

To keep things as clear as possible - Vsync doesn't only limit FPS. It rather keeps it fixed at constant value e.g.

if system is capable of generating between 30 and 59 FPS the game FPS will be 30 fps and nothing else - not 33 and not 25 either. And like I wrote to you in a PM - FPS limit does not prevent image tearing.

That's the beauty of knowledge. Many times you feel you were better off it before :D

What a waste of time these all Vsync posts!!! :doh:

 

 

I can say with 90% probability that DCS Black Shark uses special Vsync implementation (wait for Vsync ?) that allowes to bypass Vsync limitation re FPS being integer fractions of monitor refresh rate so you don't need any tools for forcing tripple buffering (like D3DOverrider).

 

Just enjoy it people! Other simmers are not that lucky! :thumbup:

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Can you say that again I didn't have my glass's on....