Similar to Chinese opera, there are no language restrictions on entries for film festivals. In recent years, more local film makers have incorporated non-standard Chinese varieties into their films. For example, the local movie "881" revived the popularity of getai after it was released. Getai, which is mainly conducted in Hokkien and Teochew, became more popular with the younger generations since the release of the movie. On the effect triggered by the release of the movie "881", Professor Chua Beng Huat, Head of the Department of Sociology in the National University of Singapore (NUS), commented in the Straits Times that """putting Hokkien on the silver screen gives Hokkien a kind of rebellious effect. It's like the return of the repressed"." The success of 881 is also reflected by album sales of "881" movie soundtrack, which became the first local film soundtrack to hit platinum in Singapore. In other instances, the movie "Singapore Ga Ga", a tissue seller sings a Hokkien song while "Perth" features a Singaporean taxi driver using Hokkien and Cantonese. Local directors have commented that non-standard Chinese varieties are vital as there are some expressions which just cannot be put across in Mandarin Chinese, and that the different Chinese varieties are an important part of Singapore that adds a sense of authenticity that locals will enjoy.