How to identify a word after "@" as an %artist%?

This is filename @Artist_name_1 feat @Artist_name_2 pres SingleName - Title.mp3

I want to add to %artist% tag only the first word inmediately after "@" and separate it with a ";":
%artist%: Artist_name_1; Artist_name_2;

I don't want to add "feat" or "pres SingleName".

  1. Convert: Filename - Tag
    Formatstring: %artist% feat %artist% pres %dummy%
    ... this will give ...
    ARTIST: @Artist_name_1 @Artist_name_2

  2. Action: Format value
    Field: ARTIST
    Formatstring: $trimLeft(%ARTIST%,'@')
    ... or ...
    Formatstring: $cutLeft(%ARTIST%,1)

  3. Action: Format value
    Field: ARTIST
    Formatstring: $replace(%ARTIST%,' @','; ')

  4. Action: Format value
    Field: ARTIST
    Formatstring: %ARTIST%'; '

Result:
ARTIST=Artist_name_1; Artist_name_2;

DD.20141227.1907.CET

All steps in one go ...

Action : Format value Field : ARTIST Formatstring: $regexp(%_filename%,'^@(.+?)\sfeat\s@(.+?)\spres.+$','$1; $2; ')

DD.20141227.1954.CET