[mythtv-users] Could someone just clarify a TV out question?
mail at simon-bell.net
Wed Oct 24 10:09:45 UTC 2007
> I have been doing a lot of reading on the subject of MythTV and
> outputting to a TV, due to a problem I'm having.
> The smooth playback I get from my 'off the shelf' digibox is not
> replicated by MythTV, camera 'pans' or news tickers etc.
> Would I be right in saying this can never be corrected just using a
> graphic boards TV out and that the only way to fix it is to use a TV
> card with a TV out also.
> And, does this problem apply to digital outs also eg. DVI or HDMI
> straight to a HD TV or does using digital eliminate the problem?
> Sorry if this means people repeating themselves, I just need it spelled out!
> > I don't think he's describing stuttering, but rather an interlacing
> > or frame rate issue. Maybe he could clarify if there's actual
> > stuttering, or if he's seeing camera pans and news tickers sort of
> > slowing and speeding up instead of moving smoothly. The latter is a
> > common symptom of the frame rate of the video and the frame rate of
> > the display not lining up. I see it pretty routinely when playing
> > back DVDs (24 fps) on my PC's monitor (60 Hz). There's no way to
> > evenly divide 24 into 60 so playback will never be perfectly smooth.
> > The original poster is playing back TV content on a TV, so in theory
> > it ought to be smooth. I've never set up TV out, though, so I'm not
> > sure what the problem could be or if there's a way to fix it. I'm
> > curious, though, because I *will* be setting up TV out soon.
> > > I'm curious about this as well. I have an fx5200 using the TVOut
> > > (actaully twinview using an LCD Monitor and the TVOut). Anyway, watching
> > > regular SD TV programs is fine, but it's not even close to good enough
> > > for sports, not even golf. I would love to be able to watch football and
> > > be able to replay things since the normal broadcasts seem to show less
> > > and less replays. Anyway, I've noticed if I put on LiveTV on a channel
> > > with a ticker the ticker is not smooth.
> > >
> > > If I play a program with a ticker and I look at the TV and at the
> > > Monitor (unfortunately not right next to each other) the TV seems vary
> > > between stuttering and smooth, while on the monitor it's much more
> > > consistent, but still not what I would call smooth.
> > >
> > > Does this sound more like you describe as an interlacing or frame rate
> > > issue?
> > >
> > > James
> > > > Yeah, that sounds like the classic symptoms of one.
> > > >
> > > > Unfortunately, I know it when I see it, but I'm not very familiar
> > > > with how to solve it!
> > > > > There has been some recent discussion around this subject in the thread
> > > > > "Video quality?":
> > > > > http://mythtv.org/pipermail/mythtv-users/2007-September/197063.html
> > > > >
> > > > > If you cannot get your monitor to use the same refresh rate as your
> > > > > source video signal (e.g. 50Hz for PAL) then you could be out of luck -
> > > > > as far as I can tell from what others say whilst some systems do a bit
> > > > > of cunning rate adaption in their deinterlacing algorithms, Myth
> > > > > currently doesn't.
> > > > >
> > > > > I'd be interested to hear if matching refresh to that of your source
> > > > > alleviates these issues - I've not had much luck this far with my
> > > > > monitor, but knowing it made a difference might motivate me to somehow
> > > > > "try harder" (or spend cash on different hardware :-/ )
> > > > >
> > > > > Regards,
> > > > >
> > > > > kev.
Just thought I would sum up what this topic is about with the above, as
it has been a while since it was started.
Well thanks for all the tips on soldering guys! I have now successfully
built a VGA to SCART converter :) (I documented it on the Gentoo wiki
And WOW! what a difference it makes, the picture quality is the same, if
not better than my digibox. SD TV-Out on graphics boards is poor in
As for the 'smoothness' with camera pans, news tickers and sports etc.
it is much better, far less frequent. More like a tiny pause every now
and then. It seems this issue is to do with refresh rates and syncing,
matching refresh rates with FPS etc. So I assume now it's just a case of
perfecting the modelines.
So if anyone can give me any tips that would be great! Likewise if
anyone needs help with setting up X and a VGA to SCART let me know!
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