It is Shankar Mahadevan[Ehsaan Loy]. http://www.shankarehsaanloy.com/
By closly working with ARR in his projects, Shankar, it seems, has learned the magic of weaving original melodies, and music. IMO,H J's music appears to be repetitive and all the songs have the same feeling. Amir http://dreamspringmelodies.com
