Function full_band_track 

pub fn full_band_track(
    mono: &[f64],
    rate: SampleRate,
    (from, to): (Seconds, Seconds),
    f0: Hz,
) -> LevelTrack

The full-band level track of a span.

It is the centred RMS of the mono mix in dB over one period of f0, or the fewest whole periods that span 2 ms, on a 1 ms hop from from to to. It reads only the samples of the span and half a window either side, so a note costs its own length, not the stem’s.