[Openchrome-users] cn400 image width

[John Robinson]

On 25/11/2006 14:01, Brent Shellenberg wrote:
> That's not what I meant. I'm using 720x480Noscale, and if I create a full 
> screen bitmap that has a border around the screen at about an inch from the 
> edges, with lines through the middle vertically and horizontally plus a 
> circle in the middle (using Via's windows drivers as a reference), the 
> openchrome drivers display the circle as an oval (too narrow)

Getting your circles round may just be a question of telling X what 
shape your pixels are - they're almost certainly not exactly square. I'm 
not sure I'd use VIA's drivers as any kind of reference for this.

In your xorg.conf, you need to set the DisplaySize in the Monitor 
section, to tell X what shape your pixels are. I've used the following:

# Set for 4:3 display
#       DisplaySize     192 144
# Set for 16:9 display
         DisplaySize     256 144

(but add/remove # comment marks as appropriate). Your video player may 
need to be told what the aspect ratio of the screen is too, or at least 
not to assume square pixels. On my PAL widescreen TV in 720x576Noscale, 
X then logs
   (**) VIA(0): Display dimensions: (256, 144) mm
   (**) VIA(0): DPI set to (71, 101)
The above helps get everything big enough to be readable, circles round, 
and my horizontal pixels certainly are wider than my vertical ones. On a 
4:3 TV displaying 720x480, the horizontal pixels will be narrower than 
the vertical ones, so you'll see a higher number first.

> with the border 
> to the right is almost 2 inches from the edge (this being on a 26" TV). I'd 
> like to find a way to get the openchrome drivers to produce the same visual 
> in sizing as the Via drivers do in windows (with full overscan).

These will be a modeline thing. Having said that, Noscale is not scaled, 
and anything other than Noscale e.g. more overscan will require scaling, 
which is likely to lose picture quality.

> I assume the modeline that is being used for the NTSC resolution needs 
> tweaking, but I don't know where to start. xvidtune just gives me a garbled 
> display.

Problem is, you'd need to tweak settings in the source; xorg.conf 
Modelines are only used for VGA output, and the source has hard-coded 
modelines for the TV output, expressed in terms of the register settings 
required for the various TV converter chips that are supported. This may 
change in time, but don't hold your breath...

Cheers,

John.