Module tempo 

Tempo detection for audio items, stored at import as bpm.

Eagle runs a beat tracker over the decoded audio (the first minutes of long files) and stores the tempo it settles on, between 60 and 200 BPM, with up to three decimals. Falcon estimates the same quantity its own way: a loudness-rise (“onset”) envelope at about 100 frames a second, whose autocorrelation is scored by a comb of beat periods over 60–200 BPM, with a mild preference for tempos near 120 to settle octave ties.

Constants

MAX_BPM

MIN_BPM

The tempo range searched, in beats per minute.

Functions

analysed_seconds

How much of a file Eagle analyses, by its length in seconds: the first minute of files over an hour, two minutes past ten minutes, three past three, otherwise all of it.

bpm

The tempo of an audio file in BPM, rounded to three decimals, or None if it can’t be decoded or holds no beat (silence, too short).

estimate

Estimates the tempo of mono samples at rate Hz, in BPM rounded to three decimals.

json_value

bpm as Eagle’s JSON holds it: a whole tempo without a fraction.