Filmmaker Omung Kumar says Aishwarya Rai Bachchan, whom he has directed in "Sarbjit", is a director39s actor.Omung, who earlier worked with Priyanka Chopra in "Mary Kom", believes "half the battle is won" for a director "if the casting is good".He told IANS: "First, I signed Aishwarya. I wanted a mature actress for this role who would could play a 22-year-old and a 45-year-old as well. She was planning to make her comeback and I knew her for a long time. She is a director39s actor.""Sarbjit" will narrate the struggle of Dalbir Kaur, whose sole aim in life was to get her brother, who had been mistakenly taken to be an Indian spy, out of the Pakistani jail. Randeep plays Sarabjit Singh, while Aishwarya is seen essaying his sister.Omung also believes that biopics need stars to reach a wider audience."It is important to have a star in a biopic if you want that reach. I could have made this with a newcomer also, but it would have been a smaller film. Big actors obviously help a film," he said.Asked if it was a conscious effort to make a biopic yet again post the success of "Mary Kom", Omung said: "I don39t make biopics with any such intentions, and it was not a conscious effort at all. Last year, when I got this script, I really liked it. Whatever I make a film on, my only motive is that it should be an actor39s best role.""That39s the highlight of my film."