[MPlayer-users] wrong aspect on widescreen monitor

[kay]

I'd like to upgrade from a crt monitor which I run on 1024x768 resolution
to a tft widescreen monitor, resolution 1440x900.

But when I play a dvd or a file from disc, mplayer displays too wide,
with a wrong aspect, even though it detects that my monitor is running
at 1440x900.

Except for the (probably not relevant) line about "Uninit audio filters",
the only difference with running mplayer -v dvd://1 on the crt and tft
monitors, when I do a test, is

crt: vo: X11 running at 1024x768 with depth 24 and 32 bpp (":1.0" => local display)
tft: vo: X11 running at 1440x900 with depth 24 and 32 bpp (":0.0" => local display)

crt: [xv] dx: 0 dy: 0 dw: 768 dh: 576
tft: [xv] dx: 0 dy: 0 dw: 922 dh: 576

The lines about aspect were identical on crt and tft:
Movie-Aspect is 1.33:1 - prescaling to correct movie aspect.
VO Config (720x576->768x576,flags=0,'MPlayer',0x32315659)
VO: [xv] 720x576 => 768x576 Planar YV12
VO: Description: X11/Xv

On 1024x768 crt monitor this resulted in the correct aspect, on the 1440x900 tft
monitor in a to wide aspect. I can correct this manually with -x nnn but since
that uses a absolute number I have to find out the correct number for each different
movie, which is really inconvenient. For some reason Xine displays correctly, but
I would rather keep using mplayer.

Is there some way to persuade mplayer to display the correct aspect automatically?

TIA
kay