convert to upper case letters in the beginning of a word

[parafux]

i need the regular expression to convert all words of a filename so every word begins with an upper case letter

e.g.

the file
my favorite song.mp3
gets converted to
My Favorite Song.mp3

any suggestions?

[antp]

You can't use the action dedicated to that? ("change case")

I am not sure it is possible via regular expressions to do character replacement like that