One of the most highly regarded and popular figures in the classical world, Gustavo Dudamel is best known for his talents as a conductor. But in October, the music director of the Los Angeles Philharmonic will unveil his maiden voyage as a film composer.

The Liberator,” which opens Oct. 3, spans the critical decades that shaped Simon Bolivar into the leader who rallied a revolution in South America in the early 19th century. It’s a Venezuelan/Spanish co-production and stars Venezuela native Edgar Ramirez (who also produced) as Bolivar.

It was Dudamel’s friendship with director Alberto Arvelo that involved him as a music adviser in the film’s early stages. Both men also hail from Venezuela and met in 2006 when the director made a documentary about the country’s music education program, El Sistema — Dudamel’s alma mater and the model for the L.A. Phil’s Youth Orchestra Los Angeles (Yola).

“Gustavo was helping me conceive the film’s musical style and helping me find references for the shooting,” Arvelo says. “He started suggesting melodies and brilliant ideas, (then) orchestrations … and suddenly he was already composing the music. I remember the moment, leaning on the piano at his home, when we both realized that Gustavo was already the composer.”

Dudamel began writing in summer 2012. Though a celebrity in the concert hall, he’s composed very little music since his amateur efforts as a teenager (“Let’s say they were not very deep or great pieces,” he laughs). He’s been fascinated with film music from his youth, though, and called on an experienced friend for advice.

“I invite John Williams to my house to play for him,” he says. “When he arrived I was so afraid, and very nervous. I started to play, (and he told) me, ‘Look, with this simple theme you can create a complete film score.’ It was amazing, because I started to write — in the beginning — in a very symphonic, modern way. But at the end, was not like that.”

Dudamel built the score around a simple motif inspired, partly, by Aaron Copland’s “Fanfare for the Common Man.” “This common guy became such a hero for us,” he says. “He put all his soul, even his money, for the freedom of people.” He scored the film’s battle scenes with a counterintuitive, introspective approach. “The battle of Boyaca, for example, is presented with a miserere a cappella,” Arvelo says.

Throughout the score, which was performed by the Simon Bolivar Symphony Orchestra in Caracas in January 2013, Dudamel spotlights instruments indigenous to Latin America, including the cuatro and an arsenal of unique flutes made by their player, Pedro Eustache.

“(Pedro) recorded the same music like three times with different flutes,” says Dudamel. “He even played a flute he made of an ostrich egg. Insane wonderful.”

It’s somewhat unexpected that Dudamel, who conducts and champions modern concert music, composed such an emotionally sincere and accessible score. “At the end, it’s very simple,” he says. “It’s harmony, it’s three or four motifs happening all the time, and the rhythmical ethnic thing. Nothing else. Because the image is so charged (with) beauty, and everything else that comes, that if you put too much it becomes a wedding cake.”