[mythtv-users] Is my MythTV an UpConverting DVD Player?

Jonathan Rogers jonner at teegra.net
Fri Nov 9 04:04:23 UTC 2007

On Nov 8, 2007 10:43 PM, MythTV User <mythuser at mydean.com> wrote:

>  yeah, this confuses me too, whether its the linux box or the display...
> on the same note, isnt it when I record, say a 720p program OTA, and my
> Xorg is 1080p, Myth upscales it to 1080p? Im assuming that it is the same
> case with playing the DVD...

Unfortunately, the answers to these questions can vary depending on your X
server's configuration, the MythTV configuration, and how the display is
connected to the video device in the computer. To determine the X server's
current resolution, you can look at the output of the xdpyinfo command:
"xdpyinfo |grep dimensions:" should give dimensions like 640x480 or
1600x1200 or 1920x1080. When MythTV plays video, it generally gets scaled by
the video card to those dimensions. If that's the native resolution of the
display, such as an LCD TV or monitor, those should be the exact pixels that
you see.

However, everything is complicated by MythTV's ability to switch resolutions
and the display's internal scaling. I have MythTV leave the video mode
alone, so Xorg generally has a resolution of 1280x768 or 1368x768 while
playing video through DVI on my 1366x768 native resolution LCD TV. Since I
can't match the TV's native resolution exactly (it doesn't seem to have a
1:1 pixel mapping mode even for DVI input), the TV is always scaling the
image too. Although this redundant scaling bothered me a lot initially and
makes small text look jaggy, I realized that for MythTV playing full screen
video, it has little impact on image quality. Obviously, a better design of
display would allow the video card to control individual pixels via DVI or

Jonathan Rogers
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