# LV2 Time

http://lv2plug.in/ns/ext/time
Properties for describing time.

Version | 1.4
Date | 2018-03-16
Discuss | devel@lists.lv2plug.in (subscribe)
Developer | David Robillard

- Index
- Reference
- History
- API

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.

## Index

Classes | Properties | Files
--- | --- | ---
Position Rate Time | bar barBeat beat beatUnit beatsPerBar beatsPerMinute frame framesPerSecond position speed | lv2-time.doap.ttl time.h time.ttl

## Reference

### Class time:Position

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.

In range of | time:position

### Class time:Rate

Rate

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

Sub-class of | time:Position
In domain of | time:beatsPerMinute
| time:beatsPerBar
| time:framesPerSecond
| time:beatUnit
| time:speed

### Class time:Time

Time

A point in time in some unit/dimension.

Sub-class of | time:Position
In domain of | time:beat
| time:frame
| time:barBeat
| time:bar

### Property time:bar

bar

OWL Type | Datatype Property
Domain | time:Time
Range | xsd:long

### Property time:barBeat

beat within bar

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

OWL Type | Datatype Property
Domain | time:Time
Range | xsd:float

### Property time:beat

beat

OWL Type | Datatype Property
Domain | time:Time
Range | xsd:double

### Property time:beatUnit

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.

OWL Type | Datatype Property
Domain | time:Rate
Range | xsd:nonNegativeInteger

### Property time:beatsPerBar

beats per bar

OWL Type | Datatype Property
Domain | time:Rate
Range | xsd:float

### Property time:beatsPerMinute

beats per minute

Tempo in beats per minute.

OWL Type | Datatype Property
Domain | time:Rate
Range | xsd:float

### Property time:frame

frame

OWL Type | Datatype Property
Domain | time:Time
Range | xsd:long

### Property time:framesPerSecond

frames per second

Frame rate in frames per second.

OWL Type | Datatype Property
Domain | time:Rate
Range | xsd:float

### Property time:position

position

OWL Type | Object Property
Range | time:Position

### Property time:speed

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.

OWL Type | Datatype Property
Domain | time:Rate
Range | xsd:float

## History

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.