baeuchlein on 11/5/2008 at 14:48
I have a strange problem with Thief 2 and a Radeon 9250 graphics card.
In dark areas, I see "snow" on the screen, as if I was using a TV with a badly tuned antenna. The "snow" stops (it's becoming "stationary", it does not completely vanish) if the game loads something from hard or compact disk, e.g. if I press O for "Objectives". Changing the game's resolution just makes the "snow" more fine-grained (and thus less easily visible), but it's still present then. If I take two screenshots in succession without moving and then switch between both pictures, I see the "snow" in these screenshots, too. So it's not just a display problem, but there was something different in the computer's or the video card's RAM between the two screenshots.
The "snow" vanishes completely when a movie is playing in Thief 2 or while I'm looking at a menu or at an in-game readable (book or scroll). And so far, the "snow" only appeared in Thief 2. It does not appear in Thief 1, System Shock 2, Vampire: The Masquerade - Bloodlines or Blood Omen 2 (even when set to 640x480 resolution with 16 bit colors, just like in Thief 2). Neither did it ever appear while using another Windows program or while looking at the computer's BIOS menu screens.
Other computers do not show this "snow". If I take ot the Radeon 9250 and put a Radeon 9550 in it's place, the computer looks for a new driver but finds it already in the Windows system directory. Thus, the 9550's driver was installed with the 9250's. Both may use the same driver; they're both Radeons after all. But with the Radeon 9550, the "snow" is gone. If I put the 9250 in again, there's no message telling me the computer is looking for drivers, so apparently there is not much of a change. Nevertheless, it's "snowing" again after the return of the Radeon 9250.
The OS is Windows 98 SE, the drivers are ATI's Catalyst 5.2 drivers of 2005. As far as I know, these were the latest drivers that worked with this old OS. The mainboard is an ASRock K7VT4A Pro and the Radeons are used in the AGP slot.
If the "snow" would appear in other games, I'd guess that the card's hardware is beginning to fail, but since it's only Thief 2 and only with this one card, I can merely guess what's wrong here.
Has anyone seen such "snow" in Thief 2? Or does anyone have an idea how I could find out what's wrong here? This "snow" can be annoying at times...
van HellSing on 11/5/2008 at 14:54
Are you sure you have the higher bit depth set in Thief 2? Because that "snow" sounds like the dithering you get with the default bit depth.
baeuchlein on 13/5/2008 at 09:16
Yesterday I had Thief 2 running with a resolution of 640x480 and 16 bit color depth. Not only did the appropriate line in the options menu (640x480x16) light up, but I verified that I was using this mode by changing the refresh rate for this mode. My monitor confirmed the refresh rates set, thus the game really used 16 bit color depth. As far as I know, this is the higher bit depth you were speaking of, or am I wrong here?
And of course, it was "snowing" heavily yesterday.
van HellSing on 13/5/2008 at 10:34
I didn't use specifics because I can't remember them and I don't have T2 installed :p. Anyway, I'm quite sure that T2 can use 24 bit depth.
van HellSing on 13/5/2008 at 10:57
Checked. Guess I was wrong about the 24 bits. Funny thing is, I now get the same problem on my gf 6800ds, I didn't notice it before because it seems it was helped by Timeslip's fix (which I installed immediately after the last install for a different reason).
So, try the fix! :)
(
http://timeslip.chorrol.com/ddfix.html)
ZylonBane on 13/5/2008 at 15:00
van HellSing is correct. What you're seeing is the dither pattern nVidia cards use in 16-bit rendering modes to simulate the smoothness of 24-bit color. ATI cards do it too, though they use a different pattern.
baeuchlein on 14/5/2008 at 18:07
I tried ddfix and it removed the "snow". You're both right, obviously. Thank you for your help!
Strange thing, that the Radeon 9550 is not affected while the 9250 is. Oh well.
ZylonBane on 14/5/2008 at 20:28
Stop calling it "snow". It's not at all like snow in any conceivable way. It's a dither pattern.
baeuchlein on 16/5/2008 at 17:27
Quote Posted by ZylonBane
Stop calling it "snow". It's not at all like snow in any conceivable way. It's a dither pattern.
I do not think we're seeing the same thing here.
What I see resembles something that is frequently referred to as "snow". The quotation marks used in my posting are meant to distinguish it from any weather-induced snow, whether real or simulated in
Thief 2.
Even when Garrett stands completely still, there are tiny dots visible in the darker areas of the screen, and these dots appear to be
moving (in a random pattern), although the scenery contains no moving objects. Such an effect is commonly referred to as "snow", for example at (
http://visualsnow.com/) or (
http://en.wikipedia.org/wiki/Noise_%28video%29).
I think you're referring to some kind of pattern that would
not change if the player does neither move nor turn around. I would not call that "snow".
I am not entirely certain, by the way, that it's really a problem with dithering in my case. The only thing which is certain is that the problem apparently vanishes when I use
ddfix, which hints at a dithering problem as a possible cause. But since the documentation that's available for
ddfix lists several video related problems which are corrected with the fix, it might be something completely different.
Whatever may be causing this - I don't think anyone would first describe the phenomenon visible with my hardware as "dithering pattern", but rather as "snow" or "TV static" or "TV noise". So, unless you really manage to convince me otherwise, I'll still call it "snow" (with quotation marks).
