I am having a problem when I connect my LG plasma tv (with a native resolution of 1024x768 pixels) to my 12.04 laptop. The pixels (actual pixels, not the signal) of my TV are stretched so it gets his 16:9 ratio. The pixels are rectangular (1.3333x1). Everything I display from my laptop oviously get stretched (4:3 stretched to 16:9).

There is a different dpi in X and Y needed for it to display properly (some kind of anamorphic mode). Default Ubuntu uses a dpi of 96x96. I can change it using xrandr, but only square eg 100x100 or 70x70.

Already looked here, but it seems Ubuntu totally ignore the displaySize in xorg.conf

When I use the code below to see the dpi and nothing I do changes it. The displaySize also stays the same (calculated using 96 dpi and the resolution)

xdpyinfo | grep -B2 resolution

I use the propretary ATI drivers for my ATI Mobility Radeon HD 50xx but it is the same with the Radeon drivers.

My temporary solution is to use:

xrandr --output DFP1 --mode 1024x768 --scale 1.333333333333x1 --output LVDS --off

But with this the right side of the screen is nog accesable. This is a known problem with xrandr --scale and ubuntu. This is because of a patch for the mouse/windows not going outside the screen.

I search a way to change the DisplaySize or the dpi(to something not square like 128x96) when I connect the display.