[mythtv-users] 0.24+fixes - tearing, /dev/rtc permissions and getting openGL to work

Andrew Herron totallymaxed at gmail.com
Thu Feb 24 02:37:08 UTC 2011


On Thu, Feb 24, 2011 at 1:58 AM, Mark Kendall <mark.kendall at gmail.com>wrote:

> On 24 February 2011 09:33, Mike <mythtv at dtmc.ca> wrote:
> > In the pursuit of a perfect mythtv frontend, I have recently bought a
> > Zotac Nvidia ION frontend which I have compiled and installed mythtv
> > 0.24+fixes on U10.10.
> >
> > HD playback works with three things that are bugging me and I can't
> > find a solution despite scanning fourms & blogs.
> >
> > i) very slight tearing about midway across the screen typically on
> > horizonatl panning
> > ii) /dev/rtc is symlinked to /dev/rtc0 which only have root access
> permissions
> > iii) Player(0): Waited 100ms for video buffers messages occasionally
> > iv)  I have seen, with usleep moreso, the sound lagging the video
> >
> > The tearing problem is likely related to Vsync and OpenGL.  I have
> > instructed nvidia-settings to enable this feature.  However, in (ii) I
> > see it using usleep unless I start mythfrontend as sudo/root.  Then I
> > see RTC.  I've never seen OpenGL method.
>
> Enabling OpenGL vsync in nvidia-settings will do nothing for VDPAU
> tearing. NVIDIA's VDPAU implementation is entirely standalone in that
> respect and manages vsync separately.
>
> There is no OpenGL vsync in MythTV as of 0.24.
>
> > What I would like to know is how to ensure/check/enable OpenGL as this
> > seems to be a problem with tearing and possibly the timing method.
> > Problem (iv) seems to be much better when RTC is used so how do I fix
> > (ii)?  I can change the permissions but they dont persist a reboot.
> >
> > I see OpenGL is available as I have advanced desktop effects working.
>
> This is the root cause of your problems. You need to disable the
> composite extension (search the wiki and/or the list archives). Using
> the composite extension will not only hurt performance (you want those
> GPU cycles for deinterlacing etc - especially on an ION board) but
> will also break vsync. From memory, there may be a compiz setting that
> works around the vsync issue but you're really better off without it.
>
> regards
>
> Mark
>
>
Hi Mark,

Add the following to your xorg.conf to disable composite;

Section "Extensions"
        Option  "Composite" "disable"
EndSection

This certainly got rid of tearing for me on my Revo's.

All the best


Andrew

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