[winswitch] issue with forwarding x to a lower res monitor from a virtual Xvfb

Antoine Martin antoine at nagafix.co.uk
Sun Nov 15 09:12:57 GMT 2015

On 15/11/15 14:44, Zenny wrote:
> Hi,
> xpra is very interesting, but I am encountering an issue or say cannot
> figure out exactly how to achieve the following.
> 1. Start a xvfb based virtual x instance in a resolution say 4k
> (3840x2160) in one machine (server) with say libreoffice impress, and
> broadcast using 'xpra shadow :10"
Please include the exact command line used for starting the Xvfb and 
> 2. Access that instance from another machine (laptop) using 'xpra
> attach ssh:hostname:10'
> 3. Screencapture the :10 inside the same machine at 4K.
Using which tool?
> But it does not allow me to capture in 4K but at the same resolution
> as of the rendering laptop.
I have tested here with Xdummy and that worked fine.
> I checked Xdummy related to Ubuntu instruction at
> https://www.xpra.org/trac/wiki/Xdummy, but to no avail.
Are you using Xvfb or Xdummy? What distribution and version?
> Any hints would be highly appreciated. Thanks!
You may also be interested in the following 0.16 features:
* ability to NOT change the virtual display to match the client's 
resolution using:
XPRA_RANDR=0 xpra start ...
Shadow mode is A LOT less efficient than the regular "start" mode.
* desktop scaling, which allows you to upscale or downscale the server 
resolution when displayed on the client:
So you could render at 4k and display at 2k for example (though the main 
purpose of this ticket is to do the opposite to save bandwidth).
* "sync-xvfb" fix for screen capture tools:


> Cheers,
> /z
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