[mythtv-users] Underscan/Overscan problem: how do I solve it?

Robin Smith 1canuck2 at gmail.com
Mon Jul 18 21:42:38 EDT 2005


Almost all TVs apply overscan to the signal they recieve. In other
words, the TV takes the 720 x 576 signal you are sending it, and
probably crops 5-10% off of each side, so you are likely losing 40-ish
pixels to the left and right and 30-ish to the top and bottom.

Supposedly, you can get a better modeline for your TV out that will
take care of the crop by giving you the correct timings and pixels,
"inside" of the 720x576, but I gave up and simply could not get it
working. Instead, I went the second best route and had my Myth GUI
display in a window (its in the Appearance section of settings. I then
messed with the offsets to get the top left corner where I wanted it,
then messed with the height/width to get the bottom right corner where
I wanted it.

BTW, the crop you are seeing in the GUI is also happening to your TV
playback, so once you get the GUI right, you might want to mess with
having Myth playback TV using the same setting as the GUI, there's a
menu option somewhere in Settings to let you do this, you'll see a lot
more of the picture once you do this.

Robin

On 7/18/05, Oscar Curero <oscar at naiandei.net> wrote:
> Hi,
> 
> I don't know if this problem belongs to mythtv or ivtv. Anyway, I can see the
> videos with great quality, but the mythtv menus (and kde, firefox...
> everything but videos is "too expanded". I mean, I can't see the borders of
> the image because they are out of the tv. I'm running X.org (suse 9.3) with
> PAL system and a widescreen tv (16:9):
> 
> xorg.conf:
> 
> Section "Monitor"
>   Identifier "PAL TV"
>   HorizSync 30-68
>   VertRefresh 50-120
>   Mode "720x576"
>   DotClock 42.6
>   HTimings 720 760 832 944
>   VTimings 576 577 580 602
>   Flags "-HSync" "-VSync"
>   EndMode
> EndSection
> 
> Section "Screen"
>   Identifier "TV Screen"
>   Device "Hauppauge PVR350"
>   Monitor "PAL TV"
>   DefaultDepth 24
>   DefaultFbbpp 32
>   Subsection "Display"
>   Depth 24
>   FbBpp 32
>   Modes "720x576"
>   EndSubsection
> EndSection
> 
> 
> Section "ServerLayout"
>  Identifier "Layout[all]"
>  InputDevice "Keyboard[0]" "CoreKeyboard"
>  InputDevice "Mouse[1]" "CorePointer"
>  Option "Clone" "off"
>  Option "Xinerama" "off"
>  Screen "TV Screen"
> EndSection
> 
> Section "DRI"
>   Group "video"
>   Mode 0660
> EndSection
> 
> Section "Device"
>   Identifier "Hauppauge PVR350"
>   Driver "ivtvdev"
>   Option "fbdev" "/dev/fb1"
>   BusID "2:9:0"
> EndSection
> 
> In mythtv there are some controls, I though that they could solve this
> problem, but they seems to do nothing (I read the mythtv documentation...).
> 
> What's the solution?
> --
> Oscar Curero - Linux user: 306877
> --    GPG keyID: 0xE0EA0B24    --
> 
> 
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> 
> 
> 
>


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