We’re showing some fascinating music documentaries this week, and all of them deal in some way with cross-cultural influences. “Gilles Apap: Renegade Fiddler” spotlights a brilliant but controversial classical violinist whose musical interests are too eclectic to be contained by the western written tradition alone. “The Pied Piper of Hutzovina” focuses on the meeting point between “traditional” Russian Gypsy music and Punk. “Fangafrika” takes us to a huge hip hop festival in Burkina Faso, where that quintessentially American synthesis (rap) is being synthesized yet again. “Guca” introduces us to the brass band repertoire of the Balkans, a joyous offspring of the Turkish Janissary bands that accompanied the Ottoman troops so many generations ago. And as if to bookend our survey, “Brasileirinho” is about choro music, the cross between the western classical tradition, African improvisation and rhythms, and the saudade of Portuguese folk music. While we are sometimes daunted by the monolithic and jaded pop music of our time, it is incredibly refreshing to dip into these hybrids, and to know that music itself is always capable of infinite combinations, and that musicians will ever remain open to that process.