beatsPerMeasure

The beatsPerMeasure property defines the number of beats in one measure, equivalent to the numerator of a time signature.

Default Value

new Fraction(4)  // 4 beats per measure (4/4 time)

Expression Examples

Common Time Signatures

new Fraction(4)  // 4/4 (common time)
new Fraction(3)  // 3/4 (waltz time)
new Fraction(2)  // 2/4 (march time)
new Fraction(6)  // 6/8 (compound duple)

Reference BaseNote

module.baseNote.getVariable('beatsPerMeasure')

How It Affects Measure Length

The measure length (in seconds) is calculated as:

measureLength = beatsPerMeasure / tempo * 60

// At 120 BPM with 4 beats per measure:
// 4 / 120 * 60 = 2 seconds

Access via:

module.findMeasureLength(module.baseNote)

Common Time Signatures

Time Signature	beatsPerMeasure	Description
4/4	4	Common time, most popular
3/4	3	Waltz, minuet
2/4	2	March, polka
6/8	6	Compound duple (two groups of 3)
5/4	5	Irregular meter
7/8	7	Irregular meter

Measure-Relative Timing

Use beatsPerMeasure for measure-aligned timing:

// Start at measure 2
module.findMeasureLength(module.baseNote).mul(new Fraction(2))

// Duration of half a measure
module.findMeasureLength(module.baseNote).mul(new Fraction(1, 2))

Visualization

• Vertical dashed lines on the workspace indicate measure boundaries
• Measure lines are spaced according to the calculated measure length
• The spacing changes if tempo or beatsPerMeasure changes

Changing Time Signature

To change the time signature for the composition:

1. Click the BaseNote (orange circle)
2. Find beatsPerMeasure in the Variable Widget
3. Set the new value (e.g., new Fraction(3) for 3/4 time)

All measure-relative expressions will automatically update.

Mixed Meters

While most compositions use a single time signature, you can create meter changes by having certain notes define their own beatsPerMeasure. Notes referencing these will use the new meter.

See Also

• tempo - Speed in BPM
• duration - Note length
• Working with Measures - Measure tutorial