The tension is building and nerves are kicking in as we reach the semi-final stage of BBC Young Musician 2012. The five winners of the keyboard, brass, strings, woodwind and percussion categories go head-to-head at the Royal Welsh College of Music and Drama in Cardiff, each hoping to impress the jury and win one of three places in the final of this prestigious competition. Making the all-important decisions are composer and performer Tansy Davies; Marshall Marcus, director of the London Southbank Centre's Sistema Programme; prominent British pianist, composer and teacher Huw Watkins; and Gareth Jones, conductor and founder of Sinfonia Cymru. Clemency Burton-Hill goes behind the scenes to give us all the competition news and introduces profiles of the five talented semi-finalists, as well as highlights from their extraordinary performances.