Ubuntu Tutorials

Warning: This post is a rant regarding external displays and projectors. If you’ve ever been frustrated and want a possible solution to keep in your back pocket for your next presentation, read on. If you are a hermit, never leaving your mothers basement, you can go back to whatever it is that you do..

I was just trolling the interwebs looking for something to entertain me, and I came across a video of a conference presentation. I was bored so I clicked play, and then spent the next five minutes (as did the audience at the conference) waiting and watching as innumerable nerds tried to get the projector working. This is ridiculous.

How many of you have presented at a conference, Linux User Group or other such forum and had trouble with the projector? I know I have. I had issues when I presented at OSCON just this last year, and I think I’ve had trouble at just about every conference I’ve been to.

This not only makes the presenter and organizers look bad, but in turn make Linux look bad as well. We spend all of our time talking about how Linux can do everything just short of save humanity from itself, yet we can’t tell you how because we can’t get the damned display to use the projector!

I want to outline two simple steps that I’ve used to get mirrored output on additional displays. This includes external LCD/CRT monitors, projectors, etc. I have had success with this on a number of machines as well. It should work for you, and please try this at your next presentation. If not to make Linux look better, but to make yourself and your presentation look more professional (I can’t help you with your content however).

xrandr
xrandr --output VGA --auto

Anytime I have needed mirrored display between a laptop (most commonly used to present with) and a projector or external display, those two commands have come through for me. Now, I’m not promising extended display. I’m not promising perfect maximum resolution, but I am promising actual video coming from the external display.

The xrandr command should be standard on most any distribution, and should properly find the available resolutions of any hardware output (ie; LVDS, VGA, etc). The only potential issue I see with this method is that the projector can’t support your resolution, which can be bypassed by lowering your resolution to that of the projector and running the commands again.

Ohh, and my biggest piece of presenting advice is please, please do a practice run with a projector or external display *before* the big day. That way you can test this (and other) methods before you’ve got a hundred people watching and waiting.

I’ve blogged in the past about setting up extended display on the MacBook (second gen), but I thought I’d update the post for Ubuntu 8.04.  I notice there are some small differences, which are likely caused by the updates to Xorg.  I’ll post my steps and my xorg.conf file below.

Extended Display on the MacBook

First, I tried to use the new Screen Resolution tool but it did not detect either monitor properly.  It does detect the MacBook display when it is the only display, but when my external monitor is plugged in everything gets screwed up.

I had to do things by hand using xrandr, and I had to add three lines to my xorg.conf file.  There isn’t much to it, but not as straight-forward as it could be with the graphical tools.

1. The first step is to figure out the sum of both resolutions.  ie; 1280×800 + 1440×900 = 2720 x 1700.  Take the resolutions from your MacBook (which should be 1280×800) and add it to the resolution of your external monitor.  Make note of the result.
2. Update your xorg.conf file to include the new, combined, resolution (example below)
3. Restart X (logout & login or ctrl-alt-bkspace)
4. xrandr –output VGA –auto
5. xrandr –output VGA –above LVDS

Here is a copy of my xorg.conf file.  It is default except for the three additional lines:


# xorg.conf (X.Org X Window System server configuration file)
#
# This file was generated by dexconf, the Debian X Configuration tool, using
# values from the debconf database.
#
# Edit this file with caution, and see the xorg.conf manual page.
# (Type "man xorg.conf" at the shell prompt.)
#
# This file is automatically updated on xserver-xorg package upgrades *only*
# if it has not been modified since the last upgrade of the xserver-xorg
# package.
#
# If you have edited this file but would like it to be automatically updated
# again, run the following command:
#   sudo dpkg-reconfigure -phigh xserver-xorg

Section “InputDevice”
Identifier    “Generic Keyboard”
Driver        “kbd”
Option        “XkbRules”    “xorg”
Option        “XkbModel”    “pc105″
Option        “XkbLayout”    “us”
Option        “XkbOptions”    “lv3:ralt_switch”
EndSection

Section “InputDevice”
Identifier    “Configured Mouse”
Driver        “mouse”
Option        “CorePointer”
EndSection

Section “InputDevice”
Identifier    “Synaptics Touchpad”
Driver        “synaptics”
Option        “SendCoreEvents”    “true”
Option        “Device”        “/dev/psaux”
Option        “Protocol”        “auto-dev”
Option        “HorizEdgeScroll”    “0″
EndSection

Section “Device”
Identifier    “Configured Video Device”
EndSection

Section “Monitor”
Identifier    “Configured Monitor”
EndSection

Section “Screen”
Identifier    “Default Screen”
Monitor        “Configured Monitor”
Device        “Configured Video Device”

# added SubSection “Display” until EndSubSection
SubSection “Display”
Virtual 2720 1700
EndSubSection

EndSection

Section “ServerLayout”
Identifier    “Default Layout”
Screen        “Default Screen”
InputDevice    “Synaptics Touchpad”
EndSection