[mythtv] Merging the 'render' branch

[Andreas Mayer]

>> When using the NVidia graphics card (driver version 430.26 first,
>>   now 440.31) with playback profile "NVDEC Standard":
>>   SD LiveTV and UHD Live LiveTV works fine but channel change to
>>     HD channels and sometimes to UHD channel results in
>>     SEGV in cuda_buffer_free (backtrace something like ...
>>     mythfrontend.TVMenuCallback -> mythfrontend.startTVNormal -> libmythtv.* ->
>>       libmythavutil.buffer_replace, buffer_pool_free,
>>       cuda_buffer_free, will provide more details as soon as possible)

>Don't worry about backtrace/more details - I've found the issue. Not
>just a CUDA/NVDEC problem - bit of on an issue with live tv channel
>switching/transitions. Now to try and fix it.

Switched to master today, no SEGV anymore (and TV db schema version OK), thank you Mark!

>> Until now I was not able to run mythfronend without X (eglfs) on both
>> systems using the Intel graphics (did not even try NVidia)
> If you still have issues, Qt may give you a hint about the problem
> with extra logging enabled:
> export QT_LOGGING_RULES=qt.qpa.*=true
The problem on the Intel system with the extra Nvidia card was that
eglfs.kms selected the Nvidia card by default (/dev/dri/card0):
qt.qpa.eglfs.kms: Found the following video devices: ("/dev/dri/card0", "/dev/dri/card1")
qt.qpa.eglfs.kms: Using "/dev/dri/card0"
drmModeGetResources failed (Operation not supported)
no screens available, assuming 24-bit color

So I had to force the use of the Intel card by using QT_QPA_EGLFS_KMS_CONFIG
and a configuration file specifing /dev/dri/card1.

The next problem was that the (default) Qt style gtk2 was trying to use a X display:
(mythfrontend:2481): Gtk-WARNING **: 21:20:35.470: cannot open display:

After setting QT_STYLE_OVERRIDE=Fusion or Windows mythfrontend was able to start,
first LiveTV tests were successful.

On the other system (with the old OS) I'm getting:
qt.qpa.egldeviceintegration: EGL device integration plugin keys: ("eglfs_kms_egldevice", "eglfs_x11")
qt.qpa.egldeviceintegration: EGL device integration plugin keys (sorted): ("eglfs_kms_egldevice", "eglfs_x11")
qt.qpa.egldeviceintegration: Trying to load device EGL integration "eglfs_kms_egldevice"
qt.qpa.eglfs.kms: New DRM/KMS on EGLDevice integration created
qt.qpa.egldeviceintegration: Using EGL device integration "eglfs_kms_egldevice"
EGL_EXT_device_base missing
So I guess I need to update the OS here first ...

My next steps will be:
Find out why eglfs does not work for the Nvidia card.
Finally find a configuration capable to be used with my UHD TV with 3840x2160 at 50/60Hz and HDR(BT2020).
Testing with RPi4B (has to arrive first).

Thank you!

Regards,
Andreas