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[Xbox-Scene]

Xbox 360: V-Sync Issues Demystified-- Posted by XanTium on June 7 00:55 EST
From teamxbox.com:

Modern developments have to remain compatible with the existing technology in some aspects, and for that reason, even if progressive signals (as well as modern displays) don't require the V-Sync pulse, it still needs to work as if the V-Sync pulse is there.
Because of that, game developers usually make use of the vertical blank interval to increase the framerate by disabling V-Sync. This allows developers to adjust the content of the framebuffer during these dead times.

As a result of turning off V-Sync, a new problem arises and that is a visual artifact in which a previously drawn frame overlaps the next one (because of the lack of synchronization), causing what is known as page tearing, because the entire picture looks like it is cut in half; the upper half containing the previous frame and the lower half the new one.
You may have experienced this problem firsthand in many recent Xbox 360 games. Perhaps you've pondered if there is a problem with your video setup or if there is a solution. We decided to go straight to the technical gurus within Microsoft for the answers.
Chris Satchell, GM of the Game Developer Group at Microsoft took a moment to answer our queries and help us understand why gamers are experiencing page tearing in a handful of Xbox 360 titles. Will this be a long term issue and something we'll see in future Xbox 360 titles? Find out what Chris had to say...

* TeamXbox: Many users have witnessed what is known as "page tearing" when playing a few Xbox 360 games, blaming a lack of vertical synchronization in those games as the cause of this visual artifact. Is it actually the lack of V-Sync as the reason for "the page tearing" seen on some Xbox 360 games, or could it be a problem with the output resolution and the user's display? Essentially we want to know exactly what is causing this visual anomaly.
* Chris Satchell: Users are correct; "Page tearing" is an artifact of changing the displayed frame of the game while the display device is partially through displaying the previous frame. Games normally choose to wait for the v-sync signal from the console to know that it is safe to swap to the new game frame in a way that will not be perceived by users. Often there is some dead-time while waiting for the v-sync signal; a buffer to make sure the game always is ready at the right time. Some games choose to cut the timing extremely tight to get more into each game frame and if for any reason a frame is not ready for the v-sync they change the frame anyway. This can result in a visual tear, but means the game-play remains smooth with no jitters. Other games decide to run a maximum consistent frame-rate that does not match exactly to the v-sync patterns this can result in higher fidelity control, but with occasional tearing (the vast majority of frames are absolutely fine).

Read More: teamxbox.com

[FreshOuttaMaps]

That's still no excuse as to why the OS itself doesn't wait for the vsync pulse when sliding out the guide panel. There is absolutely no reason for that to tear, but it does consistently.

[ensaynexotics]

i totally agree with whatever the hell you said

[xboxexpert]

Ditto

[mlapaglia]

three core processor, and they can't make a slide bar come out without jitters... my gateway 2000 with 600 mhz could do that.. sad..

[Nicroma]

I have noticed that since I got my 360 and it kinda pissed me off...wish they could fix it.

[slurrey]

Screen tearing PISSES ME OFF.
I would rather have a lower framerate than have my screen tearing up all over the place... that pisses me off to no end.

Developers should at LEAST include the option to enable Vsync. At LEAST!

[Heet]

Rent first and dont buy it if you see any of that crap.

[emko]

i thougth LCDS dont need vsync since they dont refresh like CRT. CRT REFRESH THE SCREEN really fast but LCDS change the colors on each pixel.

This post has been edited by emko: Jun 7 2006, 08:26 AM

[Joergen]

But computers still render in rows of pixels and the image is still a frame. A frame is not formed until starting from the top left pixel all rows are filled. When you want motion on the entire screen you need to update the entire image.

As for v-sync, I'd rather games like Condemned that run like utter crap (constant stuttering etc) would have the option to switch off v-sync. If you cant sustain and sync to the lowest acceptable fps (30) then dont sync at all.

And this is not some mysterious 360 problem, several PS2 and xbox1 games have vsync turned off (like jak and daxter 3) while others do it dynamically by dropping vsync whenever 30fps cannot be sustained. It is just how computers work and have worked since day one. V-sync is just a fancy gimmick from the latter days.

Of course I'd rather see all games at 60fps with vsync and zero slowdown but that wont change with any generation of hardware, but is entirely up to the skills and care of the individual developer.

As for why the guide bar tears or stutters.. there isnt a reserve of rendering power kept aside in games just so you can watch your smooth guide. Would you rather they keep 10-15% of the GPU in reserve just for a smooth guide?

Sure MS might work out a way to prioritise the processes and force v-sync while the guide is accessed but that might that mess up 25% of the games out there.

And when the antivirus program slides up its "new virus database" notification my 7800GTX and A64 4000+ stutters ingame. "BOO even my (insert insanely pathetic MHz here) could do it!"

This post has been edited by Joergen: Jun 7 2006, 12:47 PM

[twistedsymphony]

tearing of the dashboard?

I can honestly say I've NEVER seen the dashboard/guide tear on me.

While I HAVE seen screen tearing on a few game demos I've never seen it any any of my retail game, which includes some games where others have reported substantial tearing.

FWIW I'm using a DLP front projector.

[DWells55]

As a hardened PC gamer, I know screen tearing when I cna see it.  Fortunately my PC is good enough that I cna cap the FPS at 85 and V-Sync it, still perfectly smooth without tearing.  Pretty much every 360 game I've played has vicious horizontal tearing.  PD0 is really obvious, but that game sucks anyways.

[ikecomp]

Unless you had no idea what page tearing was that article wasn't worth the time it took to write. The guy being interviewed lended no real insight to what developers will be doing differently to help solve this problem. All he basically says is that it will get better.

And twisted, if you haven't seen any page tearing in your games just load up GRAW and watch the intro to the ubisoft logo and the cg footage that loads up when you stay at the start screen without any activity. The page tearing is herendous. I must admit I hardly notice the tearing when actually playing the game though. But with PDZ its really easy to notice while in game (especially during big explosions and horizontal panning)

Also the only time I notice screen tearing in the dashboard is when I stop playback of a movie or video to go back to the dashboard.

But for pete's sake developers, proper sync is important to gaming. Its really hard to immerse myself in a game when my 50" screen is tearing up to the high heavens.

This post has been edited by ikecomp: Jun 7 2006, 02:42 PM

[antz1970]

QUOTE(ikecomp @ Jun 7 2006, 02:12 PM)

Unless you had no idea what page tearing was that article wasn't worth the time it took to write. The guy being interviewed lended no real insight to what developers will be doing differently to help solve this problem. All he basically says is that it will get better.

And twisted, if you haven't seen any page tearing in your games just load up GRAW and watch the intro to the ubisoft logo and the cg footage that loads up when you stay at the start screen without any activity. The page tearing is herendous. I must admit I hardly notice the tearing when actually playing the game though. But with PDZ its really easy to notice while in game (especially during big explosions and horizontal panning)

Also the only time I notice screen tearing in the dashboard is when I stop playback of a movie or video to go back to the dashboard.

But for pete's sake developers, proper sync is important to gaming. Its really hard to immerse myself in a game when my 50" screen is tearing up to the high heavens.

i hear what u are saying about graw m8 , the ubisoft logo looks like shit , i also noticed major screen tearin when playing graw on xboxlive ,nfsmw was another one that had bad tearing, is it possible that some tvs make the problem appear worse , im using a 32 hi def lcd screen , my m8 runs on a 28 crt and i have never noticed this issue with him??

[ikecomp]

QUOTE(antz1970 @ Jun 7 2006, 08:36 AM)

i hear what u are saying about graw m8 , the ubisoft logo looks like shit , i also noticed major screen tearin when playing graw on xboxlive ,nfsmw was another one that had bad tearing, is it possible that some tvs make the problem appear worse , im using a 32 hi def lcd screen , my m8 runs on a 28 crt and i have never noticed this issue with him??

Yeah I think the type of display you have definitely plays a role in how bad or noticeable the tearing is. When I used to play the 360 on my 27" tube I hardly noticed the tearing in PDZ but man what a difference an extra 23"s of screen can make. My PDZ gaming experience went from   ..... .... ..... .....