On Saturday, the Tribeca Film Festival hosted its closing night selection of “Begin Again,” the musical valentine shot in New York directed by John Carney.

Adam Levine, who makes his big-screen debut, said he never took any acting classes. “I acted like an actor,” he said. “It was very meta.”

Levine, the lead singer of Maroon 5, said he’d been offered film roles before, but he had always turned them down. “I’d thought about it, but the things that had come my way had been less than desirable,” Levine said. “John Carney made me want to do it. I was a huge fan of what John had done with ‘Once.’”

Keira Knightley, who sings throughout the film, said she took only two music lessons. “I mean, yeah, I sing in the shower,” said Knightley, adding, “I’m not a singer. Sometimes you can be scared, and it’s going to be all right.”

Knightley talked about why the film’s original title — “Can A Song Save Your Life” — changed since it debuted at the Toronto Film Festival last year and sold to the Weinstein Co. for about $7 million.

“I think they tested it and the test audiences didn’t like the old title pretty unanimously,” she said. “The test audiences unanimously liked this title.”

Carney said that the original name was never meant to stick.

“It was a thing I wrote down to remind me what the film was about,” he said. “It’s also kind of a pretentious title. We didn’t want to set something up like we were going to give all the answers to everything.”

Harvey Weinstein, who has slated “Begin Again” for a July 4 release, introduced the film and thanked Robert De Niro and Jane Rosenthal for starting the festival in 2002. The after-party, held at Tribeca Grill, included a visit from New York Mayor Bill de Blasio and his wife Chirlane McCray.

Rosenthal said she considered this year’s festival a big success. She was most proud of the opening night selection, the Nas documentary “Time Is Illmatic,” which was funded by the Tribeca Film Institute. “It was a film that was nurtured inside Tribeca, and it had the response that it did,” Rosenthal said. “It was amazing, and also to close with a movie like ‘Begin Again’ that was shot here in New York.”

Is she musically inclined herself? “I say that I sing,” she confessed. “If you ask anybody in my family, they say no.”

(Pictured: Adam Levine and Keira Knightley at the “Begin Again” party at Tribeca Grill)