Android : Get audio playing speed android

let me describe my situation. I'm developing a music visualizer for android. thank to Visualizer class, i can get the waveform and fft data to visualize as graphic on the screen. Now i want something more, the speed of the effect must base on the mood/speed of current playing audio (ie: "romance" is slow, "wakawaka" is fast), I've spent a whole day for searching but got no ideas, please help me