At the Pacific Film Archives, Berkeley, a series of films about music and musicians continues Wednesdays through July. Last week, Step Across the Border played to a largely artist/musician audience. The film, with cinematography by Oscar Salgado, follows improv musician/composer and local resident Fred Frith collecting sounds and making music around the world. The film, grainy, stark black & white, made this a visual as well as aural experience. Frith was heard in person this spring at 21 Grand Gallery, Oakland. Next up in the series: A Tickle in the Heart.