[mythtv-users] Recommendations for front end replacement

Andre mythtv-list at dinkum.org.uk
Tue Dec 6 15:06:40 UTC 2011


On 6 Dec 2011, at 14:29, Kenni Lund wrote:

> 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.

I haven't yet seen any of these postprocessing modes that aren't dramatically improved by switching them off!

Yes, I have seen an awful lot of flat panel TVs.

Andre




> 
> 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
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