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

[Mike]

Thanks for recommending this it seems to have stopped the tearing!

The Zotac box seems to be pretty maxed out but now playing HDTV pretty smoothly.

I see if I start mythtv with sudo that its using RTC.  This is
inconvenient but at least works.

The last two mysteries I have are:
- is opengl important/preferable over RTC
- my screen size appears about 1cm wider than screen.

I've also read up on the second mystery.  I have ended up using NVIDIA
overscan feature to shrink the screen back to fit in the screen.  Pre
U10.10 (latest NVDIA drivers) I have had numerous problems with native
resolution vs screen/desktop resolution.  Right now, NVIDIA has picked
full-HD which is a pain to read anything on screen but fits if I use
overscan feature (set to 100).  This was a huge improvement from
U10.04 and older setup.  I also switched to HDMI which made audio more
interesting but seemed to make graphics more stable.

Is the screen-scaling problem affecting any performance?  So far I'm
fairly pleased with the display out using Temporal 1x de-interlacing
mode in Mythtv. Any guidence on what this should be for optimal
playback for ION chipset?  I assume it also depends on the attached
display capabilities... which is pretty basic in my setup.

There is a little blur on fast montion such as hockey games (the only
thing I actually want to watch!) but maybe this is as good as it gets?

I have a Panasonic 50" plasma... again, the NIDVIA U10.10 driver seems
to recognise it (unlike earlier Ubuntu installs) and this time around
has picked HD... but I'm not sure this is the native resolution of the
screen.  Changing thiswith NVIDIA  makes a desktop not fit on screen.
Changing the xorg.config file usually ends up with a balnk
screen/broken X11.

Thanks for everyones help thus far... a big improvement... with Mythtv
0.24 and a tweaked Xorg.conf file.
Mike.

On 23 February 2011 20:58, 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
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