[mythtv-users] Experience with upgrade of Xubuntu 18.04 to 20.04

[Tim Pletcher]

>
> An alternative workaround to specifying the i965 driver is to add the
> following to the device section of xorg.conf:
>
> Option "DRI" "3"
>
> The problem appears to be a known issue with intel UHD500 / latest Mesa
> and intel driver (
> https://gitlab.freedesktop.org/xorg/driver/xf86-video-intel/-/issues/193
> ).
>
>
If using the default modern kernel modesetting intel driver rather than the
legacy intel xorg driver package (xserver-xorg-video-intel), the issue with
opengl applications is altogether avoided.  However, without xorg.conf
options provided by the legacy driver, I had to rework my approach for
ensuring the system always boots to the correct resolution / refresh rate
in XFCE whether receiver/television are on or off and for enabling RGB
Broadcast Full for proper colorspace once x display is available.

I have also discovered another issue on 20.04 with this hardware (Apollo
Lake J3455 - Intel Gen 9 graphics) when using VAAPI deinterlacing.  The
installation now defaults to the iHD driver rather than i965 and the iHD
driver does not correctly expose all of the supported VAAPI functionality
as available.

This was causing validation of the VAAPI deinterlacers (motion_adaptive
motion_compensated etc) in mythfrontend to fail according to the
mythfrontend.log. It wasn't obvious in the video without inspecting the log
since myth will fall back to opengl deinterlacing gracefully. The issue can
also be verified by comparing the output of vainfo using iHD vs i965.

To work around, you must force the use of the i965 driver by invoking
mythfrontend as follows:
  $ LIBVA_DRIVER_NAME=i965 mythfrontend

Take away is anyone on 20.04 using VAAPI for hardware deinterlacing with
the iHD driver might want to verify whether it is working or not for their
combination of hardware and driver version.  Possibly related to the issue
under discussion here (https://github.com/intel/media-driver/issues/804) so
hopefully will get fixed in a future iHD driver release.
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