This is a vocabulary for precisely describing a position in time and the passage of time itself, in both real and musical terms.

In addition to real time (e.g. seconds), two units of time are used: frames and beats. A frame is a numbered quantum of time. Frame time is related to real-time by the frame rate or sample rate, time:framesPerSecond. A beat is a single pulse of musical time. Beat time is related to real-time by the tempo, time:beatsPerMinute.

Musical time additionally has a meter which describes passage of time in terms of musical bars. A bar is a higher level grouping of beats. The meter describes how many beats are in one bar.

Reference

ClassesProperties

Classes

Position

In range ofposition
Position

A point in time and/or the speed at which time is passing. A position is both a point and a speed, which precisely defines a time within a timeline.

Rate

Subclass ofPosition
In domain ofbeatUnit
beatsPerBar
beatsPerMinute
framesPerSecond
speed
Rate

The rate of passage of time in terms of one unit with respect to another.

Time

Subclass ofPosition
In domain ofbar
barBeat
beat
frame
Time

A point in time in some unit/dimension.

Properties

bar

TypeDatatype Property
DomainTime
Rangexsd:long
bar

barBeat

TypeDatatype Property
DomainTime
Rangexsd:float
beat within bar

The beat number within the bar, from 0 to beatsPerBar.

beat

TypeDatatype Property
DomainTime
Rangexsd:double
beat

The global running beat number. This is not the beat within a bar like barBeat, but relative to the same origin as time:bar and monotonically increases unless the transport is repositioned.

beatUnit

TypeDatatype Property
DomainRate
Rangexsd:nonNegativeInteger

Beat unit, the note value that counts as one beat. This is the bottom number in a time signature: 2 for half note, 4 for quarter note, and so on.

beatsPerBar

TypeDatatype Property
DomainRate
Rangexsd:float
beats per bar

beatsPerMinute

TypeDatatype Property
DomainRate
Rangexsd:float
beats per minute

Tempo in beats per minute.

frame

TypeDatatype Property
DomainTime
Rangexsd:long
frame

framesPerSecond

TypeDatatype Property
DomainRate
Rangexsd:float
frames per second

Frame rate in frames per second.

position

TypeObject Property
RangePosition
position

speed

TypeDatatype Property
DomainRate
Rangexsd:float
speed

The rate of the progress of time as a fraction of normal speed. For example, a rate of 0.0 is stopped, 1.0 is rolling at normal speed, 0.5 is rolling at half speed, -1.0 is reverse, and so on.

History

Version 1.6 (2019-02-03)
  • Clarify time:beat origin.
Version 1.4 (2016-07-31)
  • Define LV2_TIME_PREFIX.
Version 1.2 (2012-10-14)
  • Use consistent label style.
Version 1.0 (2012-04-17)
  • Initial release.