[ Spanish ]

Linux configuration

To configure new modes in the Linux X-Server window system, just edit its configuration file. Its name and location can vary across distributions but generally is at /etc/X11 and named XF86Config for X version 3.x, XF86Config-4 for X version 4.x and xorg.conf for X.org.

If in doubt, look at the boot logs, for X version 3.x and 4.x they are in file /var/log/XFree86.0.log and for X.org in /var/log/Xorg.0.log, look for text (==) Using config file:.

Relevant sections are Section "Monitor" and Section "Screen". The first section defines monitor frequency ranges and compatible modes and the second one the modes the X system will actually use.

Section "Monitor"
   Identifier "TV"
   VendorName "None"
   ModelName "None"
   HorizSync 15-17
   VertRefresh 48-62
   Modeline "PAL" 13.500 720 736 800 864 576 581 586 625 interlace -hsync -vsync
   Modeline "NTSC" 12.210 640 664 720 776 480 488 496 525 interlace -hsync -vsync
   Modeline "PALM" 13.475 720 736 800 856 480 489 495 525 interlace -hsync -vsync

Section "Screen"
   Identifier "Screen0"
   Device ...
   Monitor "TV"
   DefaultDepth 24
   Subsection "Display"
      Depth 24
      Modes "PAL" "NTSC" "PALM"

Add these sections and disable your current Section "Screen" adding # at the beginning of each line. You can restore your current configuration undoing the Section "Screen" change.


Modelines provided in this example are useful to play PAL or NTSC video but there are many other Modelines you can use for other purposes. See the section Useful modes. When more than one mode exists in section Modes of Section "Screen", X system will use the first one by default but you can change between them pressing Control Alt + (+ in numerical keypad).

To get the best results it is strongly recommended to install the latest drivers available for your video card. The correct operation of interlaced modes and overlays depend on the driver.

If only the half top of a video is displayed or it flashes badly, your video drivers do not handle properly overlays in interlaced modes. First try to upgrade your drivers, if that does not fix the issue you can still attempt to play videos disabling the use of overlays (hardware acceleration of video). For example in MPlayer you can use these parameters:

mplayer -vo x11 <file>

and in xine these ones will do:

xine -V XShm <file>

Overlays allow the video card to perform video scaling and colour space conversion by hardware. Disabling them may require more CPU power but I have not noticed any performance problems on moderate PCs (Pentium III or higher).

Written in December 2007 by Jeroni Paul
Copyright © 2007 Jeroni Paul.
Back to adapter cables