Director Clint Eastwood saw three versions of the Tony Award- winning musical before casting the film adaptation of Jersey Boys, charting the rise of 1960s pop-vocal group The Four Seasons from the mean streets of New Jersey to the top of the charts.

With hit songs like Sherry, Rag Doll, Dawn and Big Girls Don’t Cry, the rags-to-riches tale of the group’s struggle to overcome their humble beginnings, Jersey Boys won four Tonys, including best musical, in 2006.

Eastwood, 84, knew that finding the right actors was the key to transforming the hit jukebox musical, among the longest running shows on Broadway, into the film that opened on Friday.

“Casting for me is one of the most important things next to the writing,” Eastwood, a double Oscar winner for Unforgiven and Million Dollar Baby, said.

“If properly cast it takes place very easily, but if not you are fighting an uphill battle.”

Instead of opting for Hollywood names, Eastwood went back to the stage to find his stars.

John Lloyd Young recreates his Tony-winning role as singer Frankie Valli, whose falsetto tenor propelled the group to the big time.

The four main actors: John Lloyd Young, Vincent Piazza, Erich Bergen and Michael Lomenda discuss a few points in Jersey Boys.

Erich Bergen, as songwriter/keyboard player Bob Gaudio, who composed many of the group’s hits, and Michael Lomenda, as bass guitarist Nick Massi, reprise their touring company roles.

Boardwalk Empire’s Vincent Piazza, who plays hot-headed manager and lead guitarist Tommy DeVito, knows the only way out of the neighbourhood is to join the army or the mob or get famous. Piazza is the only member of the group who was not in a stage production.

Christopher Walken, another Oscar winner, plays mobster Gyp DeCarlo, the group’s godfather figure and mentor to Valli.

Eastwood admired the musical and just tried to “open it up, give it a certain realism” in the film.

In an unusual twist, the actors speak directly to the camera, giving audiences personal insights.

I wanted to open up the musical, give it a certain realism

“It is my favourite thing about the film, so unexpected and a little bit disconcerting at first,” said Bergen, who in one scene is shown watching Eastwood in the 1960s TV show Rawhide.

“But what I think it does is keep the audience completely engaged,” he added. “It keeps the audience feeling like we are watching them. In a way it recreates the theatrical experience in the film.”

Eastwood, a jazz buff who directed Bird, a biographical film about saxophonist Charlie Parker and produced a documentary about pianist Dave Brubeck, met Valli many years ago and was a fan of The Four Seasons.

“I love doing films that have music and musicians, and in this case, singers,” said Eastwood. “I think Can’t Take My Eyes Off You is one of the real classic songs of that era and would have been a classic song in the ‘40s, ‘50s or ‘30s, or any time.”