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The musical model

Why Gloopy measures everything in beats, what the tempo map does, and how scales and tuning sit on top. This is background — for the exact definitions, see The Gloopy model.

Everything is in beats — and a beat is a quarter note

Every position and length in Gloopy — a note's start, a clip's length, a marker, a loop, an automation point — is expressed in beats, and a beat is always a quarter note. Not "one count of the current time signature", not seconds: a fixed, unambiguous quarter note.

That single choice buys a lot:

  • Tempo-independence. A note at beat 4 is at beat 4 whether the song is 90 BPM or 140. Change the tempo and the music stretches in time without any position being rewritten.
  • One unit everywhere. The piano roll, the step grid, automation, the API, and the file format all speak beats. There's no conversion layer to get wrong.
  • Stable files. Because clips store beats, not seconds or samples, the composition text doesn't churn when you change the tempo — the numbers are the same.

Notes are quarter-note-relative to their clip: a note's start is measured from the clip's beginning, and the clip's position on the timeline is where it lives in the song. Move the clip and every note moves with it, untouched.

Tempo and the tempo map

Most songs have one tempo — a single BPM. But a composition can also hold a tempo map: a sorted list of (beat, bpm) markers. Between two markers the tempo is constant, so the map is piecewise — a beat span integrates to seconds segment by segment. Before the first marker, the first marker's tempo applies; an empty map just means the one constant tempo.

This is the bridge between the two worlds: beats are the musical grid, but your ears (and the rendered WAV) live in seconds. The tempo map is the exact conversion between them, and the render honours it — so a mid-song accelerando comes out right.

Time signature and the bar grid

The time signature sets how many beats make a bar — it drives the bar ruler and the bar . beat . tick position readout. It does not change the beat unit: 3/4 and 4/4 both count in quarter notes; they differ only in where the barlines fall. That's why the position display and the underlying beat numbers can be reasoned about separately.

A piece can also change meter partway through — a 4/4 verse into a 6/8 bridge. Like the tempo map, this is a sorted list of changes, each taking effect at a bar line; the ruler renumbers the bars and spaces the barlines accordingly from that point on, and the metronome accents the new downbeats. Right-click the arrangement ruler to add or remove a change (or set the initial, bar-1 signature). Because clip and note positions are stored in beats — not bars — inserting a meter change never moves your existing material; only the barlines drawn over it move.

Scales and tuning

Two more layers sit on top of the beat grid, both optional:

  • A project scale — a root and a scale type (major, minor, …). It highlights in-scale rows in the piano roll and powers snap-to-scale when you draw or move notes. It's an aid to writing, not a constraint on what can sound.
  • A tuning — by default 12-tone equal temperament, but you can load a Scala .scl file for microtuning, which retunes the pitches themselves.

Scale is about which notes you pick; tuning is about what frequency each note is. They're independent.

See also