E-learning/teaching

This page documents the setup of a Linux system for screencasting

On Screen Display

Show Keyboard commands

When showing software it's usefull for the students to see which keyboard shortcuts are pressed. If your screen resolution is smaller than 32767 pixels in either direction you can use screenkey, an on screen display (OSD) which be installed like this:

 apt install screenkey

will install the screenkey application. Run it from the taskbar:

Make sure to check "Show modifier sequences only" otherwise everyone can read your password inputs...

Show Mouse Clicks

no solution yet

Stream Canon 5D via USB

   modprobe v4l2loopback
   gphoto2 --stdout --capture-movie | gst-launch-1.0 fdsrc fd=0 ! decodebin name=dec ! queue ! videoconvert ! tee ! v4l2sink device=/dev/video0

Source: https://stackoverflow.com/questions/12278688/canon-dslr-video-loop-back-using-v4l2loopback-and-edsdk-liveview

Stream from OBS to a virtual camera source

We can't stream directly from OBS into Jitsi, BigBlueBitton, Google Meet, Skype, etc. For this wee need a virtual camera source.

  sudo modprobe v4l2loopback devices=1 video_nr=10 card_label="OBS Cam" exclusive_caps=1
  sudo apt install qtbase5-dev
  git clone --recursive https://github.com/obsproject/obs-studio.git
  git clone https://github.com/CatxFish/obs-v4l2sink.git
  cd obs-v4l2sink
  mkdir build && cd build
  cmake -DLIBOBS_INCLUDE_DIR="../../obs-studio/libobs" -DCMAKE_INSTALL_PREFIX=/usr ..
  make -j4
  sudo make install

Source: https://srcco.de/posts/using-obs-studio-with-v4l2-for-google-hangouts-meet.html

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