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

[Zenny]

On 11/16/15, Antoine Martin <antoine at nagafix.co.uk> wrote:
> On 15/11/15 16:51, Zenny wrote:
>> On 11/15/15, Antoine Martin <antoine at nagafix.co.uk> wrote:
>>> 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
>>> libreoffice.
>> $ Xvfb :10 -screen 0 4096x2160x24+32 -fbdir /var/tmp &
>> $ export DISPLAY=:10.1
> Could this be a typo? I've used this instead:
> export DISPLAY=:10

Yep that was a typo. Apology for the oversight.

>> $ libreoffice & / i3 & / lxsession -s LUBUNTU -e LXDE
> Both libreoffice and lxsession crash when I try on Fedora 23, with Xvfb
> or Xdummy.
>> $ xpra shadow :10
>>>> 2. Access that instance from another machine (laptop) using 'xpra
>>>> attach ssh:hostname:10'
>> $ xpra attach ssh:HOSTNAME:10
>>>> 3. Screencapture the :10 inside the same machine at 4K.
>>> Using which tool?
>> initially with ffmpeg and then with xwd / maim
> Command lines?
> I started an xterm with "xterm -geometry 600x100" and captured it fine
> with scrot.
> Both with Xvfb and Xdummy.
>>>> 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.
>> With Xdummy, once I attach to the remote machine with xpra, the ffmpeg
>> fails as it says "the capturing region lies out of the range." or
>> something like this.
> Having the exact command line and error message may help.
>>>> 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?
>> Tried with Xvfb, didn't work and then with Xdummy. Still experimenting.
>> ;-)
>>
>> $ lsb_release -a
>> LSB
>> Version:	core-2.0-amd64:core-2.0-noarch:core-3.0-amd64:core-3.0-noarch:core-3.1-amd64:core-3.1-noarch:core-3.2-amd64:core-3.2-noarch:core-4.0-amd64:core-4.0-noarch:core-4.1-amd64:core-4.1-noarch:security-4.0-amd64:security-4.0-noarch:security-4.1-amd64:security-4.1-noarch
>> Distributor ID:	Ubuntu
>> Description:	Ubuntu 14.04.3 LTS
>> Release:	14.04
>> Codename:	trusty
>>
>> xpra  is at v0.15.8-2 and xvfb is at v1.15.1-0ubuntu2.7
> Xdummy is problematic on Ubuntu - it is disabled for most Ubuntu versions.

I have got xserver-xorg-video-dummy 1:0.3.7-1build1 installed. Yet do
you mean it will be problematic?!

>>>> 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 ...
>>> See:
>>> http://xpra.org/trac/changeset/11229
>>> 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:
>>> http://xpra.org/trac/ticket/976
>>> 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:
>>> http://xpra.org/trac/ticket/988
>> Very interesting. Is there a binary of this dev release?
> There are fairly recent builds here:
> http://xpra.org/beta
>
> Cheers
> Antoine
>
>>
>> Thanks for taking time to reply.
>>
>> Cheers,
>> /z
>>
>>> Cheers
>>> Antoine
>>>
>>>> Cheers,
>>>> /z
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>
>