Encode ffmpeg options command doesn't work with parentheses ( ), maybe other characters as well

[Masterjun3]

In the encode configuration, if I enter -vf scale=floor(iw/2):floor(ih/2) and try to encode something, I get the following error message (and no encode is generated):

sh: 1: Syntax error: "(" unexpected

It is possible to work around this by escaping the characters with \, so -vf scale=floor\(iw/2\):floor\(ih/2\).
Maybe there are more characters where it doesn't work, so it would be nice to know which symbols exactly we have to escape. Or maybe it could be done automatically.