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keckcaves:x_windows_configuration

X Windows Configurations for Minicave

3D TV should be its own screen on the same display / X server as the main screen 1)

This is typically called a “dual-head” configuration, as opposed to a “TwinView” (Nvidia) or “Big Desktop” (ATI) configuration. Having separate screens means that one cannot move windows between the screens, but the upside is 100% reliable operation using Vrui applications.

The main monitor should be configured as the primary display (:0.0 in X11 lingo), so that the login screen, main desktop, and regular application windows appear on it, and the 3D TV should be the secondary display (:0.1).

3DTV X config

One way to output to an 3DTV is to use a special double-high resolution. The top 1080 lines are the right eye, the bottom 1080 lines are the left eye, and 45 lines between the two images form a blanking region.

The advantage of this kind of output is a full 1080p resolution, but the disadvantage is a lower 24Hz per eye refresh rate.

The following example xorg.conf fragment includes a modeline to allow for this operation:

Section "Module"
    Load  "glx"
EndSection

Section "Modes"
        Identifier "3D Modes"
        ModeLine   "1920x1080_24_stereo" 148.500 1920 2558 2602 2750
                                                 2205 2209 2214 2250
EndSection

Section "Device"
        Identifier "NVidia Device"
        Driver     "nvidia"
        Option     "NoLogo" "True"
EndSection

Section "Monitor"
        Identifier "3DTV Monitor"
        UseModes   "3D Modes"
EndSection

Section "Screen"
        Identifier   "3DTV Screen"
        Device       "NVidia Device"
        Monitor      "3DTV Monitor"
        Option       "ExactModeTimingsDVI" "True"
        DefaultDepth 24
        SubSection "Display"
                Viewport 0 0
                Depth    24
                Modes    "1920x1080_24_stereo"
        EndSubSection
EndSection

In Vrui, you would need something like the following in the “Window” section of your config:

section Window
    windowFullscreen true
    windowType SplitViewportStereo
    leftViewportPos (0, 1125), (1920, 1080)
    rightViewportPos (0, 0), (1920, 1080)
endsection
1) X has the notions of displays and screens. An X display is the user-visible part of a computer, consisting of a keyboard and mouse, and one or more monitors. An X screen refers to an actual monitor. The ideal configuration for a 3D TV system has a single X display, one X screen for the main LCD, and one X screen for the 3D TV.
keckcaves/x_windows_configuration.txt · Last modified: 2011/08/08 14:19 by braden