[mythtv-users] Got smooth playback? please post your setup & configuratio

James Buckley xanium4332 at googlemail.com
Mon Aug 7 10:53:25 UTC 2006

I will have to create a modeline that gives exatly 50Hz, as my TV only
broadcasts 'Monitor' range values through EDID (as the DVI port is designed
for a PC). This makes it difficult to get exatly 50Hz, as most calculation
software/websites round the number to 2dp.

Still, if thats what I need then....

Couple of questions....
- what does "OpenGL vsync" do?
- should I try and get XvMC working?
- I remember someone saying to turn of OpenGL Vsync when using BOB, is this

Thanks in advance

On 07/08/06, Julian Edwards <myth at julian-edwards.com> wrote:
> James Buckley wrote:
> > I've been down this road before...
> >
> > I'm using an 37" LG 37LP1D. It takes 1360x768 @ 50Hz without a hitch
> > (infact it's taken almost every modeline I've ever given it!). But
> > it's getting the refresh to be exactly 50Hz which I find the hardest.
> > On xtiming, if I type 50 for the refresh rate, when it's calculated it
> > normally says something like "Actually 50.04". If I use a refresh like
> > 49.98, I can get it to say 50, but I think the value is still being
> > rounded. How important is it to get a perfect 50Hz refresh.
> >
> > Also, I think some of the jerkyness is caused by the rubbishy graphics
> > card. If I run glxgears, it uses 100% CPU (basically as much as it
> > can), and if I do some CPU intensive task (like opening openoffice.org
> > <http://openoffice.org> :P) it stutters really bad. I think that may
> > be causing some of the erratic stutters I get (on top of the generally
> > stuttery playback), and may be leading to the prebuffer pauses.
> >
> > I think I need a decent (i.e. normal) graphics card. :(
> >
> > Thanks so far
> There's nothing wrong with your graphics card!  glxgears doesn't use any
> kind of vertical sync so will attempt to draw as fast as possible, hence
> the high CPU load.
> Like Wim said, you need a 50Hz modeline (yes, it's important to get
> exactly 50Hz).  If you run X up with --logverbose 5 it will tell you
> more about the modelines that it's using and what the vertical refresh
> rate is.  In your X config, set VertRefresh to 50.0 and this will ensure
> it'll only pick a 50Hz vertical refresh rate.  You will also need to use
> OpenGL vsync in Myth.
> I am using an interlaced 50Hz modeline through svideo TV-out and OpenGL
> vsync, and it's perfectly smooth (I have interlacing issues but that's a
> different matter!)
> J
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