To create a screencast using Linux command line tools I have used the methods outlined on this page:

https://sandilands.info/sgordon/multimedia-on-linux-command-line

(Ctrl-F screencast)

This might not be the easiest method, but it was simple enough for me and uses only tools that I had installed already.

There are two scripts:

• https://sandilands.info/sgordon/doc/code/screencast captures sound from mic and video from screen, produces 2 files; and
• https://sandilands.info/sgordon/doc/code/audioscreen2video combines audio and video into one video file

You will have to make sure that the packages sox and ffmpeg are installed, using your package manager.

I copied and pasted these script into files ~/bin/screencast and ~/bin/audioscreen2video and made them executable by chmod 755 ~/bin/screencast and chmod 755 ~/bin/audioscreen2video.

You will have to modify the screencast script to set your screen resolution correctly, as follows. After the line starting # Set the screen size ... the author has included various resolution settings for his own setup, such as lenovo, home, lecture, etc, by checking the first input argument of the script using various if/elif blocks. The default setting is in the last else block screenSize=800x600. I changed this to my own screen resolution, i.e. screenSize=2560x1440, and give the script a computer name it doens't know as its first argument, e.g. stefan. You can find out your screen resolution with the xrandr command, cf. https://askubuntu.com/a/584692.

To bring the filesize down a little, I also changed the line starting with screenOptions to

screenOptions=" -preset ultrafast "

After doing this, start recording a screencast by

~/bin/screencast stefan /tmp/MTH3028

There is a 5 seconds delay before recording starts. To end the recording you hit z (in the terminal window where the screencast script is running).

This should create two files /tmp/MTH3028-audio.flac and /tmp/MTH3028-screen.mp4.

To combine the files into a single video file, use the audioscreen2video script:

~/bin/audioscreen2video /tmp/MTH3028 2020-03-16

The first argument is the same as the second argument given to screencast.

The resulting file is called /tmp/MTH3028-video-2020-03-16.mp4.