[mythtv-users] mythfrontend under KVM

Eyal Lebedinsky eyal at eyal.emu.id.au
Mon May 3 13:44:23 UTC 2021

On 03/05/2021 22.16, Darac Marjal wrote:
> On 03/05/2021 12:39, Eyal Lebedinsky wrote:
>> For a while I avoided using mythfrontend under kvm as it was mostly
>> useless for me.
>> Today I tried again and it works better, but playback, while
>> watchable, is not smooth at all.
>> On the VM, watching FHD, when paused it consumes 75% of a cpu, when
>> playing 100%.
>> Watching HD (720p) it uses 65% playing or paused.
>> The host and VM are f32 (soon to be f34).
>> The host is an 8 core "i7-9700 CPU @ 3.00GHz" with Intel GPU on board
>> and no second GPU.
> 1. What display method are you using between the client and the VM? VNC
> is a relatively "dumb" protocol and can be quite bandwidth heavy for
> full-screen video, where many pixels change each frame. Consider,
> instead, using SPICE which allows for some considerable acceleration, as
> well as forwarding of sound from the VM to the client.

I do use spice for video.

> 2. Is the Intel GPU new enough to support GVT? GVT allows certain Intel
> and NVIDIA cards to offer a "virtual card" to VMs. The virtual card can
> be used by the host for OpenGL and VAAPI acceleration. While you still
> hit the problem of how to get the image from the VM to the screen, being
> able to offload MPEG decoding from the virtual CPU to the virtual GPU
> might also help you.
> https://wiki.archlinux.org/title/Intel_GVT-g gives a nice overview of
> the process for getting GVT to work.

I think that I looked into it before and found that this does not provide 4k virtual GPU.
I will need to add the necessary boot options to see the actual resolutions offered. The GPU is:
   0000:00:02.0 VGA compatible controller [0300]: Intel Corporation CoffeeLake-S GT2 [UHD Graphics 630] [8086:3e98] (rev 02)

I try to limit experimenting on this machine but will consider this option.

>> What KVM/MythTV settings should I use for optimal performance?
>> TIA

Eyal Lebedinsky (eyal at eyal.emu.id.au)

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