I would like to get the bpm of a song analyzing the spectrum of the volume. Doing a fft what I get is a peak at the origin and of course that can't be the frequency corresponding to the bpm, so I do the following:
$\overline{h} = h - \frac{1}{l}\sum_0^l h$
where $h$ is the fft of the volume and $l$ is the length of the signal.
Now I expect the bpm frequency to show up in the interval $[1 Hz,3Hz]$ but how can I recognize it?