Chennai, Nov 25 (IANS): Director Vasanthabalan says double-Oscar winning composer A.R. Rahman's music in forthcoming Tamil period drama "Kaaviya Thalaivan" plays a pivotal role in the film.

He says the project was a challenge for the Mozart of Madras as well.

"Kaaviya Thalaivan", which releases in cinemas Friday, is the story of a group of musical theatre artists in the 1930s and 1940s.

"The reason we approached Rahman sir is because music drives the story in our film. We wanted someone who could promise us great music. Rahman sir spent nearly two years to give the kind of music, which plays a vital role in the story," Vasanthabalan told IANS.

"Even for Rahman sir, this project was challenging as he hasn't worked on something like this before. He even gave us most of the songs even before we went on floors with the film, contrary to how he usually works on a project," he said.

According to Rahman, "Kaaviya Thalaivan" allowed him to innovate with music.

"I haven't got the opportunity to compose folk music for films very often. This project gave me the freedom to innovate with that genre of music. I had to forego a Hollywood project to take out time for this film to compose 20 songs," Rahman had said earlier.

"Since it's a period film, I had to use a lot of folk tunes laced with ragas to do justice to the era in which the film is shot," Rahman said.

The film features Siddharth, Prithviraj, Vedhika Kumar, Anaika, Nassar and Thambi Ramaiah in the lead roles.