CADÊNCIA

Conductors of small ensembles rehearse against metronomes built for solo practice. They want to set a tempo curve — sixteen bars at 92, ritardando into the bridge, settle at 86 — and have it play back through a single trustworthy click that the whole room can hear.

Every metronome app I tried treated tempo as a single dial. Music does not.

Tempo is a piecewise curve: a list of sections, each with a target BPM, a transition style (step, linear, exponential), and an optional accent pattern. Cadência renders that curve to a sample-accurate Web Audio click via Tone.js, scheduled ahead of audio time so the click never glitches even when the tab loses focus.

A bar/beat counter is wired to a quiet visual pulse on a second screen, so a conductor can glance at a tablet on the music stand without breaking eye contact with the section.

Rehearsal patches save the whole curve as a named preset; the conductor loads "Bach BWV 565 — second pass" and the room knows what is coming.

Used in real rehearsals by two ensembles I play with. The "no, slower" arguments shortened by an order of magnitude.

A small open-source piece, but the design choice — tempo-as-curve, not tempo-as-dial — is the bit I am proud of.