Screencasting from Qubes OS

User Support
#1

For quick tutorials and demos, I make screencasts to share with clients and colleagues, typically using OBS Studio. What is a sane approach to achieving this in Qubes OS?

Required:

  • Screencast of mouse pointer and multiple Windows
  • Real-time voice recording

Nice to have:

  • Real-time webcam recording
  • As viewed from dom0 (to demo Qubes OS itself, but this is low priority for me)

Options that I can make out are:

  • Running an AppVM in full-screen mode, giving it access to the mic/webcam, installing OBS Studio and making screencasts in that context

  • As above without full-screen mode, not clear to me what this would look like

  • Installing OBS Studio (or some other tool) in dom0, and recording the whole Qubes OS desktop, but even if possible I assume this is not a good idea

Are any of these options obviously worth/not worth pursuing? Any options I’ve missed?

#2

This seems to work well with OBS Studio, though it doesn’t give you the dom0 view:

Create a nested X server via Xephyr. The Arch Linux wiki has a good description of how to do this: https://wiki.archlinux.org/index.php/Xephyr . Then share the nested X server. You can have an arbitrary number of windows there and even start any window manager in this X server instance.

#3

Capture card setup

There is also this setup I found interesting:

setup

Qubes —HDMI—> Capture Card (HDMI to USB) —USB–> Qubes --> AppVM w/ OBS -> jitsi

Explanation from within Qubes (youtube link!) and from the outside perspective of the user (youtube link!).

3 Likes
Video streaming one monitor
#4

Create a nested X server via Xephyr. The Arch Linux wiki has a good description of how to do this: https://wiki.archlinux.org/index.php/Xephyr . Then share the nested X server. You can have an arbitrary number of windows there and even start any window manager in this X server instance.
Hi,
personally I am completely new to Arch Linux. Therefore please tell me with what commands I can install Xephyr within Fedora 32 or Debian 10. In order to screencast my Qube manager and my VMs with OBS-Studio.
Thank you.

#5

Debian: the package is xserver-xephyr (install via sudo apt install xserver-xephyr)

Fedora: the package is xorg-x11-server-Xephyr (install via sudo dnf install xorg-x11-server-Xephyr)

#6

Thank you for your help. I managed to install Xephyr successfully in Fedora 32. Also I achieved to execute Xephyr -br -ac -noreset -screen 800x600 :1 . However that was it. So far I don`t understand how to record my screen with OBS Studio and Xephyr. Please help me. Stay healthy & safe. Thank you.

#7

Just to make sure we are on the same page, this will enable you to record what is happening in the black window started by running the Xephyr command. This window is a virtual screen or more properly a new virtual server. This won’t let you record the entire desktop.

To make things show up in this virtual screen, you have to prepend your commands with DISPLAY=:1 as explained in the Arch Wiki page. For instance, DISPLAY=:1 firefox should open Firefox in this virtual screen. You may also want to start a window manager in this screen first (see the wiki for an example as well).

If you run OBS in the same qube, there should be an option to select the screen/X server environment you want to share. You should be able to select :1 or something like that. At least it worked in the past. In the worst case, start OBS in the same screen. I think this is required for something like Zoom for instance (so DISPLAY=:1 zoom).

Let me know if you run into any roadblocks and we can work from there.