[mythtv-users] IONITX-C tearing 1080p

Jim Stichnoth stichnot at gmail.com
Mon Dec 7 23:39:01 UTC 2009

On Sat, Dec 5, 2009 at 9:39 PM, Chad Voelker <chad.voelker at gmail.com> wrote:
> Hello,
> I have the Zotec ION ITX C board as a FE. It is showing considerable tearing
> on 1080i, but perfect video with 720p both coming from a HD Homerun.
> I've validated the following already:
> * VDPAU is set up in the playback profile
> * Running the most current nvidia driver (190.42)
> * Added the "Composite" "Disable" option to the "Extensions" section of
> xorg.config
> * Added "TripleBuffer" "True" option to the "Device" section of xorg.config
> * Sync to VBlank checked in OpenGL Settings section of NVIDIA X Server
> Settings
> * These recordings display fine on my laptop
> Some other details about my setup:
> * I boot from a USB thumb drive and connect to the backend via Gig Ethernet
> * Running Mythbuntu 8.10 upgraded with the Avenard repository
> * It has one 2 Gig stick of RAM
> * It is currently running at 65 degrees C
> It would be unfortunate to have to transcode. Any thoughts?

I have 3 of these boards, all displaying HDHR recordings perfectly
without tearing.  VDPAU, 190.42, netbooting, trunk.  They were also
fine when I was running 0.21 modified with VDPAU support.  One TV
displays 1280x720, and the other 2 TVs are Vizio 1366x768 models.

However, early on I had problems with tearing.  I was tearing my hair
out trying to figure out why one Vizio was fine while the other had
tearing.  I finally compared all the settings page by page, and found
the difference/culprit.  "Enable OpenGL vertical sync for timing"
needed to be UNchecked.  This is on page 1 of Setup : TV Settings :
Playback.  At the time, I believe I was running 0.21 with VDPAU
support, and probably the 185 nVidia driver.

By the way, I had another problem with the Vizio that's worth sharing,
but may not be completely relevant.  The same TV with tearing was also
experiencing some occasionally jumpy playback.  I was using a custom
modeline based on parameters from the owner's manual in order to drive
at the native 1366x768 resolution, which was not available via HDMI
EDID.  The parameters in the manual actually resulted in a frame rate
of something like 59.8 Hz, slightly lower than the 59.94 Hz of many of
my recordings.  This caused the frontend to drop a few frames from
time to time to catch up, which was noticeable at least in the 0.21
code.  Once I modified the modeline to be slightly higher than 59.94
Hz, the jumpiness went away.


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