Among the beneficial side effects of "Star Wars" and its success may be that people attracted to the rich and romantic John Williams score for the film will develop a greater appreciation of film music generally.

Sunday night's "Previn and the Pittsburgh," at 8 0'clock on Channel 26, should do anything but discourage this. Andre Previn conducts the Pittsburgh Symphony Orchestra in a splendid program of film music by Aaron Copland, Erich Wolfgang Korngold, Jerry Goldsmith and others, and then Williams himself takes the podium to conduct his own new suite of the "Star Wars" score.

It's perhaps the most attractive setting for the main themes yet, and it brings out the score's haunting, mystical qualities rather than its Korngoldian swashbuckle.

During a brief interview with Previn, Williams proves a shy and civilized chap. He tells Previn that he and director George Lucas decided the music for a film in which the visuals were other-worldy should be old." It was one of the most crucial, brilliant decisions in the making of the film.

Previn expresses his admiration for the "Star Wars" music and then says to Williams, kind of charmingly, "There's the Pittsburgh Symphony. Would you go conduct it for me?"

Director Rodney Greenberg and producer Stephen Dick make "Previn and the Pittsburgh" the best-dressed musical program on public television. Greenberg's visual and musical sense is witty and articulate; he leaves shows like "In Performance at Wolf Trap," with its sloopy, distant squints at the musicians, and the Boston Pops concerts, with those dismembering diagonally split screens, far behind.

During a selection from William Walton's music for "Henry V," Greenberg cuts to a violinist just before she starts to play, so that we see her watch expectantly for the conductor's nod. This sort of touch constitutes heavenly punctuation for an already impeccable visual recording; so do a couple of movie-style "wipes" igeniously applied to the "Star Wars" section. It closes the program on a note of triumph that is spectacularly appropriate and satisfying.