[ltp] External video on T61

[Joerg Bruehe]

Hi John !


John Jason Jordan wrote:
> On Mon, 19 May 2008 16:55:27 -0700
> John Jason Jordan <johnxj@comcast.net> dijo:
>=20
>> [[...]]
>>
>> I managed to get it to work using nvidia-settings, except the projecto=
r
>> is displaying on the screen only about 1/4 of my screen. My screen is
>> 1680 x 1050. In "X Server Display Configuration" the projecter options=

>> are Auto, 320 x 240 and 640 x 480. I need to be able to set it higher
>> in order to capture all the screen of my laptop, but the choice is not=

>> there.

Let others correct me, but AFAIK roughly it is like this:

Your "/etc/X11/xorg.conf" defines the size of your display area (in=20
pixels), typically this is the resolution of your laptop screen.
When you connect an external display (including a beamer), your laptop=20
gets informed about that device's resolution, and the X server uses that =

info to send only a partial image to that external display.
Its idea about the "display size" doesn't change.

Again AFAIK, you have two choices:
a) Force your display size to the smaller (external) value, so that
    resolution goes down and "full screen" matches the beamer.
b) Open a window whose size is no larger than the beamer resolution,
    do your presentation inside that window, and take care never to=20
exceed its boundaries with the cursor as that would make the X server=20
shift the part sent to the external output.


>>
>> Making progress, though. Further suggestions needed.
>=20
> Further difficulties.=20
>=20
> There are too many options that I don't understand on the
> nvidia-settings configuration dialog box for X Server Display
> Configuration. What is "clone"? What is "twinview"? What is "separate X=

> server"?

"clone": Both your builtin display and the external output get the same=20
image to display (modulo the size problems described above).

"twinview": AFAIK it is what often is called "Xinerama" - one big=20
workspace displayed in part on the builtin and in part via the external=20
output. Windows can be shifted to either display and can be split by the =

boundary.

"separate X server": Two separate workspaces, each with its own size.
To start a process with a window on the other workspace, use
    DISPLAY=3D:0.1 /foo/bar --arg &

>=20
> I tried several options, some of which required restarting X. I did so
> with Ctrl-Alt-Backspace. Half the time when I logged back in the screen=

> came up without my Gnome panel settings. Very strange. I don't
> understand how I am going to cram my 1680 x 1050 display onto a
> projector that will only do 640 x 480.

AFAIK, you cannot. You can either have only a part of it displayed, or=20
restrict your builtin display to the smaller external resolution.

>=20
> I ended up disabling the external projector for now. I have my Gnome
> panel settings back. Until I figure this out better I am going to leave=

> it alone. I don't understand Linux that well and I can't afford to
> screw the computer up with a project due in two weeks.
>=20
> If someone can suggest a tutorial on using external video with a T61
> with Linux, maybe I can give it another shot later.

I know this is a frequent source of problems, but it should be=20
independent of the exact model. The principle is the same everywhere,=20
just the exact capabilities and commands may differ by graphic chip and=20
driver.

IMO the most essential survival rule is: Backup your /etc/X11/xorg.conf=20
in a safe place, so that you can always go back to this working copy.
If you have several such files, for different environments (external=20
settings), give them good suffixes to keep them separate.

The second rule is: You must be able to do this recovery from the=20
command line, without using any GUI or GUI-based file manager=20
(Konqueror, Nautilus, ...), because if you screw up your X configuration =

too badly then starting X will fail, and Linux will fall back on command =

line login.


HTH,
J=F6rg

--=20
Joerg Bruehe  - persoenliche Aeusserung / speaking only for himself
mailto:joerg.bruehe@web.de