View Full Version : [all variants] seeking video details for "external" display

September 20th, 2010, 05:20 PM
If I use xdpyinfo I see details for the internal display for my laptop.

Q1: Where do I find the details for the "external monitor" port so that I might connect a reasonable projector or monitor?

Q2a: Do those details exist only AFTER I connect something? Q2b: Are there risks if the external something doesn't match up with what the video port supports? Q2c: Are there risks to the laptop presented by whatever external something I connect?

Merci d'avance,
~~~ 0;-Dan

September 21st, 2010, 08:06 PM
What you are able to connect to is dependent on the video card. If you are refferring to a laptop with an RCA video output, it should work with any monitor/projector that has an RCA in for video.

I don't think connecting any monitor into a video port will harm either the monitor nor the PC, the device most likely just won't work.

I have connected my laptop to a 50" plasma and watched Netflix as well as connecting it to the school's projector to run a slide show for a HW assignment. For the most part, if it connects then it should work.

September 22nd, 2010, 06:58 PM
My laptop has a female DB15 connector -- two actually: one on the laptop and one on the docking station.

lspci reports

Intel Corporation Mobile GM965/GL960 Integrated Graphics Controller (rev 0c)

xdpyinfo reports (about the built-in LCD display)

dimensions: 1400x1050 pixels (245x184 millimeters)
resolution: 145x145 dots per inch
depths (7): 24, 1, 4, 8, 15, 16, 32

Are modern monitors suitably "multi-sync" such that they will discover what my port is saying and work with it ... or give up?

My readings tell me there are numerous tricks to get dual display to work with X11. Is there some way to create a static default config for 1024x768 for a second display?

I'm using Jaunty (v9.04) on one box and Lucid (v10.04 LTS) on the others. It looks like config steps are wildly different between them.

~~~ 0;-Dan

September 23rd, 2010, 01:31 AM
Bump 8d;-{

September 23rd, 2010, 01:54 AM
With Intel (or ATI) video chips, I believe if you boot with an external display connected, the BIOS automatically switches to the external display (but nVidia does not). But when Ubuntu X starts, it tries to mirror both displays in a resolution that it thinks both can handle. But Linux is not always able to determine details of a VGA display, so it is not necessarily automatically optimum resolution for either display.

If you connect an external display after booting, a quick way to get X to recognize that it is there is to log out of X and back in (no need to power down, just out and back into X).

For example if I boot my laptop with Intel video, Ubuntu picks 1024x768 for both, even though laptop display is 1280x800 and external VGA might be 720p or 1080p HDTV.

So I use a script of xrandr commands to set a proper resolution for external display, turn off my laptop display, and activate the external display. And the script runs with one or two clicks by either putting a launcher in the top panel, or on the desktop.