[mythtv-users] Recommendations for front end replacement

[Kenni Lund]

2011/12/6 Brent Bolin brent.bolin at gmail.com
> ION looks fine for OTA mpeg2 HD broadcast when the scenes are close up
> and slower.  Even some football games are pretty good.  But when you
> get a large panned scenery shots stutter shows up.

My guess is that the issue has nothing to do with the performance of
your ION frontend, but instead is due to the postprocessing performed
by your TV being incompatible with your selected resolution/refresh
rate. I think this is the case, since it sounds like the same issue
that I've been fighting with on VERY similar hardware.

You wrote that your frontend is a "ZOTAC IONITX-A-U" - I have a ZOTAC
IONITX-A-U as well. Connected to that frontend you have a new Samsung
55" LED with HDMI - I have a new Samung 46" LED with HDMI.

When I turned on the smoothness-enhancing stuff on the TV ("400Hz"
according to the Samsung marketing department), the issue was even
more visible - the picture was panning smoothly in short intervals,
but with very annoying stuttering. After a day of debugging and
searching on google, I realized that the Samsung TV has issues with
stuttering when the HDMI source does not use common refresh rates
normally used by various video sources (BluRay/DVD/etc). The default
output from the Zotac board with Mythbuntu 11.04 with an
auto-generated xorg.conf was 1920x1080 at 60Hz according to the Samsung
TV - this was the resolution causing the problem on my TV. Once I
added the right modelines to the xorg.conf (some worked, some didn't)
and told MythTV to change refresh rate according to the source video,
the problem disappeared completely.

If you want to give it a try, a guide can be found at the wiki:
http://www.mythtv.org/wiki/User_Manual:JudderFree

Just to avoid confusion, the problem I'm talking about has nothing to
do with the "judder" described in the guide above (caused when playing
back for example a 23.976fps video source on a 50Hz signal to the TV),
the problem I'm talking about is stuttering caused by a bug in the
postprocessing on recent Samsung TVs. The guide above just contains
the right modelines which works for the postprocessing (aka.
smoothness/400Hz) feature on my Samsung TV.

Best regards
Kenni