One theme in the documentary is the Maels’ lifelong interest in film, and their multiple near-misses in trying to bring their music to the big screen, including a proposed collaboration with the French comedian Jacques Tati and a project with Tim Burton. So it’s ironic that just weeks after “The Sparks Brothers” arrives, they have another movie release: “Annette,” a musical written by the Maels, directed by Leos Carax, and starring Adam Driver and Marion Cotillard. The story of a comedian and opera singer who give birth to a daughter with a “unique gift,” it will open the Cannes Film Festival in July.

“Even before we had a band, the merging of music and movies just seemed so perfect,” Ron, 75, said, adding, “To be sitting on a movie set in Brussels and watching Adam Driver and Marion Cotillard singing something you wrote — it’s surreal, way beyond what we expected.” (Carax was unavailable for comment.)

Wright presented his idea to the Maels that night he saw them onstage, but they expressed some trepidation, for the same reasons they had turned down previous offers for a documentary.

“We always say that we don’t like looking back because we think it kind of paralyzes you,” said Russell, 72, encapsulating the constant creative forward motion that has defined the band’s oddly incomparable history. “The proposition of doing a documentary is kind of the opposite of that, and in our minds we thought, is it like an obituary in some sense?”