[winswitch] Fedora33 xpra h264 encoding support not working

Antoine Martin antoine at nagafix.co.uk
Fri May 21 13:10:39 BST 2021

On 21/05/2021 16:09, Terry Barnaby via shifter-users wrote:
> Hi,
> I am testing the usage of xpra between two Intel Fedora33 systems. It
> functions fine with default encoding (whatever is used) but I cannot
> enable h264 encoding to test with this.
> I have tried using the default Fedora RPM's "dnf install xpra
> xpra-codecs-freeworld xpra-html5 xpra-udev" as well as the
> https://github.com/Xpra-org/xpra RPM's.
Do not mix downstream packages like 'xpra-codecs-freeworld' and xpra's

And avoid downstream packages altogether:

> Both show the same issue.
> If I use "--encodings=h264" on a manually started server and client, the
> server messages have the error listed:
This is the wrong switch to use.
You need more than one 'encodings' enabled to be able to run correctly.

That said, with the xpra.org packages installed correctly, this doesn't
cause the problems you report below.

> "no common encodings found (server: rgb24, rgb32, grayscale, h264, auto
> vs client: h264, excluding: h264, vp8, vp9, h264+mp4, mpeg4+mp4, mpeg1,
> mpeg2, hevc)"
> So something is setting the "excluding:" part for some reason. I cannot
> find any information on why this would be.
> Any ideas on what may be happening ?
As per the documentation:
*Do not* second guess the server engine by specifying encoding(s), as
you will get it wrong and the behaviour is very likely to be sub-optimal.

If you really want to use 'h264' and not the other video encoders, you
can just use --video-encoders=x264,nvenc on the server side. Nothing
else is needed, server side or client side.
As I said, it's a bad idea but it does work and will use 'h264' whenever
it is suitable - which if far from always being the case. ie: if the
xpra server detects that the application in use is plain text (ie: a
terminal) then it will still not use a video encoding like h264. Which
is one of the reasons why you still need other encodings enabled.


> Terry
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