Screencast

Many users have asked how to make a screencast of their simulation. Here we show one solution to this question.

As mentioned in Ubuntu’s wiki, you can use may ways to record your desktop, from VLC to ffmpeg. Here we will show how to use recordmydesktop. This is a command line tool, although a graphical user interface version is also available (gtk-recordmydesktop).

Install using:

sudo apt-get install recordmydesktop

Here is a useful alias to select a window to record:

alias scast='recordmydesktop --v_bitrate 5000000 --full-shots --fps 10 --no-sound --windowid $(xwininfo | grep "Window id:" | sed -e "s/xwininfo\:\ Window id:\ // ;s/\ .*//")'

The most efficient way to make a screencast is to use low compression, so then you must know how to re-encode your video before sending it.

The official recommendations from YouTube and Vimeo (as of January 2015) are: MP4 + H.264 + AAC-LC.

You can use the following command to re-encode properly:

avconv -i out.ogv -vcodec libx264 -s hd720 -b 5000k -an out.mp4

Or, if you use sound:

avconv -i out.ogv -vcodec libx264 -acodec libfaac -s hd720 -b 5000k -ab 320k out.mp4