What is Judder?
Judder is a combination of smearing and strobing, a combined effect of “choppiness” when you move your head back and forth in the HMD. At this time, one usually sees this issue when the frequency or framerate of an app is out of sync with the frequency of the DK2 panel. This sync is very important due to the low persistence feature (a very rapid strobing effect that increases scene stability) of the DK2. Judder can get bad enough to make an app unplayable. You can learn more about judder in HMDs in this blog post
by Michael Abrash.
By default, the DK2 runtime utility is in “Direct to HMD” display mode. Many applications have problems with this display mode and will run poorly. It is recommended that you change the display mode to “Extend Desktop to HMD”.
Open App on Rift's Display
Make DK2 the Main Display
Sometimes an app will refuse to acknowledge the Rift’s display, even to the extent of failing to give resolution options that are compatible with the DK2. In this case, you can force the app to open on the Rift display instead of your main display. There are several methods to make this happen, described in the video below. On Windows, there are a few apps that will do this for you, such as VR Game Manager
or Virtual Desktop
. On Mac, the process is much simpler – simply drag the folder over to the DK2 display and open the app there (you may have to squint through your Rift with one eye to do this).
Change Resolution/Frequency of Primary Display
In many cases, a system will base its refresh rate on the primary display in spite of app settings, preference settings, or control panel settings. If your regular primary display has a refresh rate of 60Hz, the app may be locked at 60fps. 60fps on the DK2’s 75Hz screen usually results in severe judder. To ensure that the app adheres to 75fps and the 75Hz refresh rate of the rift, you can make the DK2 your primary display. Once again, VR Game Manager
will handle this for you in Windows.
Most displays have a refresh rate of 60Hz. In some cases, you may be able to lower the resolution on your regular primary display, and then set the refresh rate to 75Hz to match the DK2 display.
Unity Quality Settings
If attempting to run a Unity title, experiment with quality settings. Sometimes a higher setting will run better than a lower one, depending on how the app was built. Hold “alt” while opening a “DirectToRift” executable to force a settings window to pop up.
Aero (Windows 7,Vista)
Force DirectX 9 or 11. (Windows)
Some users have reported differences in performance by enabling or disabling Windows Aero (an interface that enhances the look of Windows). You can disable Windows Aero by following this tutorial.
Some users see better results by forcing the app to load with a particular version of DirectX. Add “-force-d3d9” or “-force-d3d11” to the Target field of a shortcut.
Alternate Mirroring (Mac)
On Mac, you can trick a Unity application into adhering to the DK2’s frequency:
- Mirror your displays in the Display preferences.
- Open the app to bring up the Unity preloader.
- Choose 1920×1080 resolution, and select Windowed in the Unity preloader.
- Deactivate mirroring.
- Press play in the Unity preloader.
- Drag the window over to the Rift display. You can create a shortcut for this using Better Touch Tool. (Maximize window on next monitor)