This paper presents a novel beat detector that operates in the Huffman coded domain of a MP3 audio bitstream. We seek to answer two main questions. First, whether it is possible to extract beats without even partial decoding of a MP3 audio. Second, how to construct a low complexity algorithm to detect beats for multimedia applications in small devices such as mobile phones, if the answer to the first question is positive. Our investigation shows that beat detection in the Huffman coded domain can achieve fairly good results with a significantly reduced demand for computation. We also propose a graph-based algorithm to tackle the beat detection problem from an algorithmic perspective.