Clarification needed: Setting up 'frame' directory in make_video.sh script from OpenDA documentation

[carbonatezero]

The script linked here attempts to make a video but there is some confusion about the frame directory. It would be helpful to have more detailed instructions on how to set up the frame directory and what its contents should be.

[nilsvanvelzen]

This script is not part of the course itself but is used to create a video of the running model for illustrative purpose. In #295 I have added some comments in the code of two scripts to clarify it a bit.