[mythtv-users] TV-out settings for old PAL TV using Intel 945

David Watkins watkinshome at gmail.com
Tue Dec 16 11:44:29 UTC 2008

> To be more precise, the TV
> playback is OK but the images does not fill the screen (I have cycled
> through using 'W' but even 16:9 the native size leaves about 3cm border
> and there is shape distortion at the top corners).

I'm using an nvidia card and had to set up overscan, using nvidia
settings, to remove the distorted edges.  I think this is normal.

> 1. modeline - xrandr lists a number of 'native' resultions but I am not
> sure which is the 'best' to use or how to match them with the resolution
> settings in the Myth setup. I have also tried to load in different
> modelines recommended on various web sites but xrandr complains and will
> not use them. I am also having problems getting the card to switch to
> PAL mode (details below).

I'm running SVideo into a 28" 16:9 CRT, and using an 800x600 modeline.
 The myth menu screens look excellent.  The TV picture is [mostly]
indistiguishable from my TV's analog tuner.  The exceptions are sports
(such as football or tennis) where the action is noticeable blurred
and not quite smooth; and scrolling text, that moves a bit unevenly.
I believe that this is due to inherent limitations in the refresh rate
of the nvidia SVideo output (my input is DVB-tT.  I did try using
higher resolution modelines, including wideangle aspect ratios, but
didn't notice significant improvement, again probably due to
constraints of the SVideo conversion.  I also tried  640x480, which to
be honest looked just the same, but was a bit limiting when outside

> 2. playback profiles
> (http://mythtv.org/wiki/index.php/Playback_profiles) I think that my box
> will nearly handle "High Quality" but should I use this for an old TV?
> Which is the 'best' setting for an old TV? Setting it to 'High Quality'
> does give reasonable results but is this the correct setting?

You possibly don't need to deinterlace(since your TV probably does
that for you), so the lower horsepower playback profiles should be OK.
 I think I'm actually using CPU+.

> 3. screen settings
> (http://mythtv.org/wiki/index.php/User_Manual:Detailed_configuration_Frontend#Appearance)
>  should the GUI Height/Width be set to the same as the resolution
> selected for the display by xrandr? Should I be trying to change the
> fonts or something else to improve the OSD?

I never had to bother with these. I did set the DISPLAYSIZE parameter
in xorg.conf to get an approximately 100dpi resolution.  Couldn't get
it exactly because of the aspect ratio of the TV.

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