Smooth Gaming with Triple Buffering

Iria · Mar 20, 2006, 05:20 AM

Have you ever being in a situation where you enable v-sync to get rid of annoying image tearing, but only found out it killed your frame rate? We know v-sync caps your maximum frame rate at your screen refresh rate, which is 60 time per second for common LCD monitors. Actually playing games at 60 fps is not bad and it should provide a smooth gaming experience. However, you sometimes find the frame rate strangely capped at 30fps as soon as it drops below 60fps. At this point you probably start screaming "OMG! tearing sucks, and v-sync sucks no less!!!". It's not v-syncs fault all alone, usually it's the combination of the images being rendered using double buffering with v-sync enabled. So you asked why is double buffering evil? Basically there are two buffers in the graphics hardware, the image you seeing on the monitor is in the front buffer and the next rendered frame is in the back buffer. Since we have v-sync enabled, before the graphics hardware can swap the front and the back buffer, it needs to wait for the next vertical blank period (happens every 1/60th seconds on monitors with refresh rate 60Hz) to maintain synchronization with the monitor's refresh rate. This works fine when the graphics card can render frames faster than 60fps. If all of this makes sense to you, perhaps you can imagine what happens when the graphics card is unable to bump 60 frames per second. When that happens, the graphics card is unable to make the buffer swap because the next frame is not ready in the back buffer and it'll have to wait for the next vertical blank period to make the swap. The end result is that instead of swapping buffers 60 times per second, it's only swapping the buffer 30 times a second, and that's the reason why frame rate is capped at 30fps.

This is where triple buffering comes into play. With triple buffering enabled, now we have 3 buffers and the graphics hardware can start rendering into the 3rd buffer without having to wait for the front buffer gets swapped out.
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Read More / Source: OCWorkbench

OmegaRED · Mar 20, 2006, 05:24 AM

Ya I just read this a few minutes ago on Hardocp and couldn't figure out the practical uses for this in gaming, you need to have consistent fps to use vsync and as they mention it eats up almost all of your video card memory causing even more slowdown.

bug77 · Mar 20, 2006, 08:53 AM

At least it gives you a chance to find the sweetspot. Anyway, as you can see, memory is significantly eaten up only at very high res, with AA enabled.

liqnit · Mar 20, 2006, 09:00 AM

this sounds very intresting
maybe it should be implemnted in VGA cards

Judas · Mar 20, 2006, 04:06 PM

I can't play without Vsync... vsync can actually produce a much more stable frame rate then without...

dipstick · Mar 20, 2006, 04:11 PM

Quote:

Originally Posted by Judas

I can't play without Vsync... vsync can actually produce a much more stable frame rate then without...

I agree with this. F.E.A.R is a prime example where gameplay is like butter with Vsync and a stuttering/tearing mess without.

riles9262 · Mar 20, 2006, 05:58 PM

I use vsync and tb when possible as well. kotor and kotor 2 exhibit the change the best imo...their tearing is atrocious if you don't enable vsync.

Mar 20, 2006, 05:20 AM	#1
Iria DriverHeaven Extreme Member Join Date: Apr 2004 Posts: 7,275 Rep Power: 89	Smooth Gaming with Triple Buffering Have you ever being in a situation where you enable v-sync to get rid of annoying image tearing, but only found out it killed your frame rate? We know v-sync caps your maximum frame rate at your screen refresh rate, which is 60 time per second for common LCD monitors. Actually playing games at 60 fps is not bad and it should provide a smooth gaming experience. However, you sometimes find the frame rate strangely capped at 30fps as soon as it drops below 60fps. At this point you probably start screaming "OMG! tearing sucks, and v-sync sucks no less!!!". It's not v-syncs fault all alone, usually it's the combination of the images being rendered using double buffering with v-sync enabled. So you asked why is double buffering evil? Basically there are two buffers in the graphics hardware, the image you seeing on the monitor is in the front buffer and the next rendered frame is in the back buffer. Since we have v-sync enabled, before the graphics hardware can swap the front and the back buffer, it needs to wait for the next vertical blank period (happens every 1/60th seconds on monitors with refresh rate 60Hz) to maintain synchronization with the monitor's refresh rate. This works fine when the graphics card can render frames faster than 60fps. If all of this makes sense to you, perhaps you can imagine what happens when the graphics card is unable to bump 60 frames per second. When that happens, the graphics card is unable to make the buffer swap because the next frame is not ready in the back buffer and it'll have to wait for the next vertical blank period to make the swap. The end result is that instead of swapping buffers 60 times per second, it's only swapping the buffer 30 times a second, and that's the reason why frame rate is capped at 30fps. This is where triple buffering comes into play. With triple buffering enabled, now we have 3 buffers and the graphics hardware can start rendering into the 3rd buffer without having to wait for the front buffer gets swapped out. ___________ Read More / Source: OCWorkbench

Mar 20, 2006, 05:24 AM	#2
OmegaRED Relapsed Gamer Join Date: Oct 2002 Location: Ottawa , Canada Posts: 5,688 Rep Power: 173 System Specs	Ya I just read this a few minutes ago on Hardocp and couldn't figure out the practical uses for this in gaming, you need to have consistent fps to use vsync and as they mention it eats up almost all of your video card memory causing even more slowdown. __________________ E Penis Specs: <------------- See System Specs

Mar 20, 2006, 05:58 PM	#7
riles9262 Driverheaven brewmaster Join Date: Oct 2002 Location: British Columbia, Canada Posts: 4,842 Rep Power: 72 System Specs	I use vsync and tb when possible as well. kotor and kotor 2 exhibit the change the best imo...their tearing is atrocious if you don't enable vsync. __________________ A beer a day keeps the doctor away.

Mar 20, 2006, 08:53 AM	#3
bug77 DriverHeaven Senior Member Join Date: Oct 2003 Location: around Posts: 792 Rep Power: 0	At least it gives you a chance to find the sweetspot. Anyway, as you can see, memory is significantly eaten up only at very high res, with AA enabled.

Mar 20, 2006, 09:00 AM	#4
liqnit DriverHeaven Lover Join Date: Mar 2006 Posts: 222 Rep Power: 0	this sounds very intresting maybe it should be implemnted in VGA cards