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Using a Video Projector with Linux

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.

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Categories: Screens Tags: , ,
  1. will
    June 18, 2013 at 20:32

    Thanks this is a great tutorial! I really appreciate it :).

    If I’m honest what lead me here is a problem that I’m having on my HP laptop.- So it’s nice to see that yours is behaving itself!

    The laptop isn’t outputting any signal through HDMI to my projector (Whereas the VGA port works just fine) Have tested both the cable and the projector so I’m sure it isn’t either of those. I think it’s a Windows problem :/. So I had the idea of loading into a portable Linux OS to see if I can get some output through the HDMI port. Do you think this would be a good idea? What portable OS would you suggest that might work the best (and need less command line-y stuff :P).

    Thanks again for your tutorial :).

    Will

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