can s-video output be "tweaked"?

José Oliver Segura primijos at
Wed Nov 22 01:44:17 PST 2006

       Hi all, (hope not to be off-topic)

       I'm trying to configure s-video output from my laptop (Acer
travelmate 240, ATI Radeon Mobility 7500) to my TV (Sony  trinitron KV
32'') under Linux (Fedora Core 6).

       I'm able to see the desktop in the TV (just used atitvout to
activate s-video output), but I think the picture is not as good as it
could get: image doesn't feet 100% of the screen, is a little
displaced towards the left and, at the top, the line is not completely
straight, is a little bit curved as it gets next to the left border.
Also, when viewing some channels on dvb-t, I can see little
dots/slashes in this same place (the curved edge on the top right).
Picture also presents some little horizontal lines but only at
"objects/shapes limits" (don't know how to explain it better). I've
tried with "radeon" driver and "vesa" driver (both Xorg, I've not
tested ATI propietary drivers)

       I've tried the same s-video cable with another laptop (hp
nc8000 + windows) and it works ok (image size fits screen, no
horizontal lines at shapes edges).

      I've been looking around to see wether change some parameters in
xorg.conf file would end up with a better picture, but nothing has
worked (mainly, tested different modelines in xorg.conf), so I'm
starting to think that maybe I have some *big* misunderstanding of how
s-video output works, and maybe none of the parameters in xorg.conf
files affect that? maybe, as s-video is, in someway, "dedicated" to
TVs, everything is hardwired in the chip?

       Is it that way or is just that, maybe, I'm not getting the
right modelines/head configuration, whatever?

       Sorry about not posting xorg.conf/logs now, I'm at office and
have no access to my home's laptop, but since this is a question
related with general s-video tweaking (before going deep into details,
if it can be done), maybe is not necessary. If I get any "yes, it can
be configured!" answer, I'll be happy to continue the thread, posting
xorg.conf files :)

       In parallel to that, I'm trying also the vga<->scart option:
just bought a vga<->scart cable and plugged it from the laptop to AV/1
in the TV, but that's worse: no picture at all :-/ Maybe this case is
more sensible to modelines and TV refuses to show any signal that
doesn't fit exactly in their refresh/sync range? (I have not been able
to make this setup work undre windows, so I'm starting to blame the
vga<->scart cable, althoug the fact that a "crt" is attached to vga is
detected in bot: windows and linux)

       thanks a lot for any hit, have a good day!

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