pub const LONG_FRAME_BELOW_HZ: Hz;Expand description
The median f0 below which harmonic analysis uses its long frame.
At 44.1 kHz the frame is 8192 samples below it, else 4096: a Hann main
lobe is about 4 bins wide, so harmonics f0 apart need
N >= 4 fs / f0. At another rate the length scales with the rate, see
Stem::frame_len.