Working with Measures

Measures are the dashed vertical lines that divide the workspace into bars. They are notes — a special kind, with a start time and nothing else — and you build them into chains, where each bar starts where the last one ended.

Prerequisites: Note Dependencies, Add Rhythm.

Tempo lives on the BaseNote

Click the BaseNote and you get rows for startTime, frequency, tempo, beatsPerMeasure, and instrument. The defaults:

Property	Default
tempo	100 BPM
beatsPerMeasure	4

Click any ordinary note and you get startTime, duration, frequency, color and instrument — no tempo row. Tempo is a property of the piece, not of a note.

From tempo, two derived quantities fall out:

beat(base)              # one beat, in seconds: 60 / tempo
measure(base)           # one measure, in seconds: beatsPerMeasure × 60 / tempo

At the defaults, beat(base) is 0.6 s and measure(base) is 2.4 s.

Helpers are input sugar

You type measure(base) and tempo(base); the app stores the same bytecode as base.ml and base.tempo, and that is what the Raw: field will show you afterwards. beat() is the one helper that survives the round trip and is displayed back to you as beat(...). All three forms are equivalent — do not be surprised when your measure([1]) reappears as [1].ml.

Build a measure chain

1. Click the BaseNote, Clean Slate the workspace, and click the BaseNote again.
2. Find the row labelled Add New Measure Chain and click Add.

A dashed vertical line appears at time 0 with a small triangle at the top. That triangle is the measure's handle. The widget re-opens on it, titled Measure [1] Variables.

3. With Measure 1 selected, the widget now offers Add Measure. Click Add.

Measure 2 appears one measure-length later. Click Add again for Measure 3, and again for Measure 4.

INFO

Add Measure only appears on the last measure of a chain. If you select a measure in the middle, the button is not there — you cannot insert a bar into the middle of a chain from the widget.

Select any measure and read its startTime:

[1].t + [1].ml

"Start where measure 1 starts, plus measure 1's length." That is the chain. Each bar depends on the one before it, so lengthening any bar pushes every later bar along.

A measure widget is nearly empty

Click a measure triangle and you get:

• a startTime row,
• a Measure Duration row,
• Add Measure, if it is the last in its chain,
• EVALUATE (Evaluate to BaseNote only — no Liberate),
• DELETE NOTE.

No frequency, no duration, no colour, no instrument, and no ADD NOTE / SILENCE section. You cannot hang a note directly off a measure bar from the widget — but you can drag a library module onto one, and you can reference it from any note's expression.

Change a time signature

The Measure Duration row edits that measure's beatsPerMeasure — how many beats the bar holds.

1. Click Measure 3's triangle.
2. In the Measure Duration row, the Raw: field shows 4 (inherited from the BaseNote).
3. Change it to 3.
4. Click Save.

Measure 3 becomes a 3-beat bar. It visibly narrows, and Measure 4 and everything after it slide left, because they are chained to it. You have a 4/4, 4/4, 3/4, 4/4 piece.

WARNING

The Save button on this row is hidden until you type in the field, and the row has no Evaluated: readout — you get the raw value only. Odd meters work too: (7/8) and (5/4) are both valid.

To change the whole piece's meter instead, set beatsPerMeasure on the BaseNote. Every measure that has not overridden it follows.

Positioning notes by measure

On a bar line

The cleanest way to say "start at measure 3" is to reference measure 3. Put this in the note's startTime:

[3].t

This is robust: it stays correct even if you change the length of measure 1 or 2. Use it.

Counting from the BaseNote

base.t                          # measure 1
base.t + measure(base)          # measure 2
base.t + measure(base) * 2      # measure 3

WARNING

This arithmetic only works while every measure is the same length. The moment you give one bar a different beatsPerMeasure, measure(base) * 2 stops being "the start of measure 3". Reference the measure bar instead.

A beat inside a measure

Beat 3 of measure 2 — two beats past the bar line:

[2].t + beat(base) * 2

Beats are counted from zero, so "beat 3" is * 2.

Practical: a kick-snare pattern

Four bars of the workspace, a note on beat 1 and beat 3 of each.

Build a measure chain of four bars first, then create notes from the BaseNote and set their start times:

Note	startTime	duration
Kick, bar 1	[1].t	beat(base)
Snare, bar 1	[1].t + beat(base) * 2	beat(base)
Kick, bar 2	[2].t	beat(base)
Snare, bar 2	[2].t + beat(base) * 2	beat(base)

Now change the BaseNote's tempo. The bars, the kicks and the snares all move together, and the pattern stays a pattern. Change measure 2's Measure Duration to 3 and the second bar's snare lands correctly inside the shorter bar, while measure 3 slides left to meet it.

On per-note tempo

There is no tempo change mid-composition

The note widget exposes no tempo field on an ordinary note, so a tempo change cannot be authored in the app. Tempo is a BaseNote property, and one piece has one tempo.

You may see beat([1]) in an expression — the app writes that form itself when you drag a note. It reads note 1's tempo and, because no ordinary note can carry one, falls back to the BaseNote's. So in practice beat([N]) and beat(base) give the same answer for every note you can build in the app.

One duration this page adds

The note-length table — whole through triplet eighth, all as multiples of beat(base) — is in Add Rhythm. Measures add one entry to it: a duration of one full bar is measure(base), or equivalently beat(base) * base.bpm. Both are tempo-independent, like every duration written in beats.

Exercises

1. A waltz

Set the BaseNote's beatsPerMeasure to 3 and its tempo to 150. Build a four-bar chain and put a note on each beat. Compare with the shipped Greensleeves and Bach Minuet in G melodies in the library, both of which are in 3.

2. A hemiola

Give measures 1 and 2 a Measure Duration of 3, and measure 3 a Measure Duration of 2. Watch the chain re-flow.

3. Two chains

From the BaseNote, click Add New Measure Chain a second time. You get a second chain starting at base.t, independent of the first. Both anchor to the BaseNote; neither depends on the other.

4. Drop a melody onto a bar line

Drag Ode to Joy from the library's Melodies section onto a measure triangle. Its timing anchors to that bar; its pitches stay anchored to base.f, because a measure bar has no frequency to inherit.

What you learned

• Tempo and beatsPerMeasure live on the BaseNote; ordinary notes have neither.
• Measure chains are built with Add New Measure Chain and Add Measure, and each bar depends on the one before it.
• Measure Duration sets a per-measure time signature.
• Reference a bar ([3].t) rather than counting measure lengths.

Next

• Microtonal Composition — alternative tunings
• Complex Dependencies — deeper structures
• beatsPerMeasure reference — the property in full