[mythtv-users] Wrong Aspect Ratio

Michael T. Dean mtdean at thirdcontact.com
Thu Sep 6 15:00:43 UTC 2007

On 09/06/2007 03:41 AM, Gabe Rubin wrote:
> On 9/5/07, Michael T. Dean <mtdean at thirdcontact.com> wrote:
>>> I can't figure out why the backend doesn't have those options.
>> The xinerama section is only displayed if X reports that you are using
>> multiple xinerama screens.  Twinview isn't xinerama (it's an
>> NVIDIA-proprietary approach).
> And how do you make sure that you are not using xinerama?  I have my
> myth hooked up to one display (a tv) and triplechecked my xorg.conf to
> make sure there is no reference to xinerama or multiple displays, but
> I still have that setting available in appearances.  I am thinking it
> is causing some screwy stuff to go on, so fixing it would be nice.

If you're using NVIDIA drivers, there are some important issues.  Though
TwinView is not Xinerama and can be used without enabling Xinerama,
TwinView is compatible with Xinerama and can be used with Xinerama. 
However, TwinView can /only/ be used with the NVIDIA-driver-provided
Xinerama extension.

If you see a line:

    (++) Xinerama: enabled

in your X log, you're using the X server-provided Xinerama extension.
Without that line, (if Xinerama is in use), you're using the
NVIDIA-driver-provided Xinerama extension.  Therefore, lack of existence
of a line indicating Xinerama usage is not proof if non-usage.  :)

I recommend reading through:
and, of course,
where you'll find things like:

Option "TwinView" "boolean"

Oh, and BTW, certain hardware can only be used on one display at a
time--including video overlays.  If using TwinView without Xinerama,
this hardware cannot be used at all.  That's probably why you don't have
a video overlay (gray OSD) on the system that doesn't have it--you're
using TwinView without Xinerama.  By using Xinerama with TwinView or by
completely disabling TwinView, you can use the video overlay.


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