“Get Low,” the first feature directed by Aaron Schneider, is based on one of those true stories that seem indistinguishable from legend. In the late 1930s a man from East Tennessee named Felix Breazeale decided to give himself a funeral before he was even dead. It was, by all accounts, a lively affair, with musical entertainment and a raffle to attract the public, and it left behind a vapor trail of mystery. Who was this character? What was he thinking?

The film’s answer to the second question is a bit unsatisfying, which is forgivable since its answer to the first question is Robert Duvall. This means that though the story sometimes wanders into hazy, corny sentiment, its protagonist (called Felix Bush, which was apparently a nickname or alias of Breazeale’s) is vivid, enigmatic and unpredictable. Mr. Duvall, now 79, has recently specialized in small, indelible character parts: the police department patriarch in “We Own the Night”; the blind survivor speaking in apocalyptic riddles in “The Road”; the sobered-up bar owner helping Jeff Bridges’s Bad Blake through “Crazy Heart.”

These contained, welcome appearances are reminders that this actor has gone nearly 50 years in movies virtually without a false note. And “Get Low,” giving him time and room to explore the crevices of a wily, wounded soul, proves that Mr. Duvall is still able to carry a movie easily and gracefully.

It is a lesser movie than “The Apostle” (1997), which he wrote and directed and which remains on of the most astute screen treatments of American religion and the American South. But Felix Bush shows an unmistakable kinship with the Apostle E. F., the wayward holy man he played in that earlier film. Mr. Duvall is too rough, too strange, too capable of surprising himself and everyone around him to be any kind of type.