The world preem of “Mistaken for Strangers,” a new doc about the relationship of two brothers on a road tour for the band the National, will open the 2013 Tribeca Film Festival on April 17.

The film, directed by Tom Berninger — brother of National frontman Matt Berninger — makes for a less high-profile opener than the studio pics that have opened the fest in prior years, including Universal’s “The Five-Year Engagement” (in 2012) and Dreamworks Animation’s “Shrek Forever After” (in 2010). As a nonfiction title with links to a music act, it falls more in line with “The Union,” the Cameron Crowe chronicle of the collaboration between Elton John and Leon Russell that kicked off Tribeca’s 2011 edition.

“To me, it’s very much about showcasing a film that captures the independent spirit and this generation’s attitude of how you find your place in the world,” said Geoff Gilmore, Tribeca’s chief creative officer. “The agenda of Tribeca is broad and multifaceted, and we’re trying to do something here that’s really appropriate as a mark of the eclecticism that defines Tribeca.”

Particularly in its early years, Tribeca has been dogged with questions about its defining identity and its place in the fest-circuit ecosystem ever. Documentary filmmaking is one of the areas in which the festival has made its mark, launching attention-getting docs including “Bully” and “Taxi to the Dark Side.”

“Mistaken for Strangers” follows filmmaker Tom Berninger as he joins his brother and his brother’s band on the act’s largest tour to date, while Berninger’s documentarian aspirations stir up tour-bus tensions. Marshall Curry exec produces with producers Matt Berninger, Carin Besser and Craig Charland.

Announcement of the festival’s opener comes in advance of the full slate next week.

As with the “Union” preem, the Tribeca screening of “Mistaken for Strangers” will be followed by a live perf from the music act that is central to the film. Venue for the screening hasn’t yet been locked, but at the moment it looks like it’ll play the Tribeca Performing Arts Center, the 915-seat venue where many of the festival’s larger events have taken place in the past.

The 12th edition of the festival runs through April 28.