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Using a Video Projector with Linux

October 20, 2008 1 comment

One of the first problems a user faces is the need to show topics and presentations with the help of a video projector and a laptop running Linux.

For some reason beyond me, Linux newcomers get turned off by the mere mention of a command line. The whole concept of using a console is like alien.

Okay, there are two options: You can try to modify your Xorg.conf file until you mess it up, destroy your computer’s GUI, and get attacked by sharks (Let’s be honest, this is not worth the effort for just a single presentation), or you can go for a fast, secure and temporary on-the-fly screen resizing.

If you chose the second options, keep reading. This was tested on my HP Pavilion dv2000, with a standard VGA port, running Fedora 9 x86_64.

First some easy stuff (OPTIONAL STEP): let’s disable the screensaver and as we want our screen to be ready and visible throughout the presentation.

$ xset s off

Next we have to take care of the external output. The command here is xrandr, which stands for “X Resize And Rotate” and is used to “allow clients to dynamically change X screens, so as to resize, rotate and reflect the root window of a screen“.

On your console type xrandr -v to check if the package is installed (99% chance it is).

$ xrandr -v
Server reports RandR version 1.2

Now, connect the video projector to the laptop. And automagically you should see… nothing, since the screens are not yet configured.

In order to verify it the system recognized the device, lets query the connected screens with the command xrandr -q

$ xrandr -q

You should see something like the following:

LVDS: minimum 320 x 200, current 1280 x 800, maximum 1280 x 800
VGA connected 1920x1440+0+0 (normal left inverted right x axis y axis) 380mm x 285mm

As you can see, there is a device named LVDS which is the “Low-voltage differential signaling” for the laptop panel, and there is also a VGA device which represents our video projector.

Here you can use the same resolution on the laptop screen and the projector or using two different resolutions. The first approach is a little less prone to errors so we are going to use it.

To clone the screen:
$ xrandr --output LVDS --auto --output VGA --auto --same-as LVDS

To extend the screen to the right in the VGA projector:
$ xrandr --output LVDS --auto --output VGA --auto --right-of LVDS

And finally, to turn off projection:
$ xrandr --output VGA --off

This method can also be used with DVI and S-VIDEO cables. Just be sure to type the correct name of the output device as it is showed with the xrandr command.

Categories: Screens Tags: , ,