Dropping frame rate in DWM (Aero) Options

[nate]

I'm not sure how many people have this problem, but I thought I'd post in case it helps anyone. Skip to the end if you just want the solution.

Since the introduction of Aero in Windows Vista I've been working on a new version of DigitalWatch that uses Direct3D instead of DirectDraw so that it can run without the desktop changing back to basic mode. While development of DW3 is ongoing (yes I'm still working on it), during the process I've discovered a problem in Aero that affects any application running Direct3D in windowed mode, including Window Media Player.

If you have a video (or any Direct3D app) running maximised on one monitor and you cause some graphical activity on the other monitor then the frame rate will drop. This can make video look stuttery.

I am running 2 screens (1920x1200@60Hz) with my start menu on the left monitor. To reproduce the problem I start playing a video in Windows Media Player, move it to the right screen and maximise the window (Note maximise, not fullscreen).

Next I load up fraps which shows the frame rate in the corner of media player. While I'm not doing anything the frame rate is 60fps. Then if I wiggle the mouse around on the taskbar over the applications to trigger those nice glowy effects, I see the frame rate in media player drop down to 50fps. I've tried it with other Direct3D applications and some drop to 30fps.

I initially thought it was just that my GPU wasn't capable of handling it, but loading GPU-Z showed that my GPU Load was nowhere near maximum.

I eventually found the solution in this technet forum thread.
http://social.technet.microsoft.com/Forums...2d-8ed184b7a45c
It's about half way down the page posted by Twizzlerite. Look for the http://pastebin.com/ links.

I applied the Force10Level9 registry change

CODE

[HKEY_CURRENT_USER\Software\Microsoft\Avalon.Graphics]
"Force10Level9"=dword:00000001

and then restarted the Desktop Window Manager service (or log off and on again). Now when I repeat the process above the frame rate stays at 60fps and the video playback is nice and smooth.

From what I read in the technet forum the problem affects some video card drivers and not others, so not everyone will need this fix. If you think you need it you can try what I did above to see if you get a frame rate drop.
I don't know excatly what the registry setting does, but it worked for me and I haven't noticed any negative side effects from it.

cheers,
nate

[PansyBush]

Now that I began using two screens, I have the same problem as well, thanks for posting these guidelines, I hope they will get me the problem resolved even though I have very little experience with Direct 3D so far.