"Der Rock ist in Wien" is totally wrong / está totalmente errado.
It means that the "Rock" is currently there in Wien.
Isso significa que o "Rock" está atualmente em Wien.
But "Der Rock ist aus Wien" means:
That you either have bought it there (in Wien) and brought it with you (e.g vacation); or that the designer maybe has made it there and is himself living in Wien...or presented it on a big show there.