LV2 Units

Units for LV2 values.

ID	http://lv2plug.in/ns/extensions/units
Version	5.12
Discuss	devel@lists.lv2plug.in (subscribe)

Index
API

This is a vocabulary for units typically used for control values in audio processing.

For example, to say that a gain control is in decibels:

@prefix units: <http://lv2plug.in/ns/extensions/units#> .
@prefix eg:    <http://example.org/> .

eg:plugin lv2:port [
    a            lv2:ControlPort , lv2:InputPort ;
    lv2:index    0 ;
    lv2:symbol   "gain" ;
    lv2:name     "Gain" ;
    units:unit   units:db
] .

Using the same form, plugins may also specify one-off units inline, to give better display hints to hosts:

eg:plugin lv2:port [
    a            lv2:ControlPort , lv2:InputPort ;
    lv2:index    0 ;
    lv2:symbol   "frob" ;
    lv2:name     "frob level" ;
    units:unit [
        a            units:Unit ;
        rdfs:label   "frobnication" ;
        units:symbol "fr" ;
        units:render "%f f"
    ]
] .

It is also possible to define conversions between various units, which makes it possible for hosts to automatically convert between units where possible. The units defined in this extension include conversion definitions where it makes sense to do so.

Index

Classes	Properties	Instances
Conversion Unit	conversion factor prefixConversion render symbol to unit	bar beat bpm cent cm coef db degree frame hz inch khz km m mhz midiNote mile min mm ms oct pc s semitone12TET

Classes

Conversion

Class

Label	Conversion
In domain of	factor
	to
In range of	conversion
	prefixConversion

A conversion from one unit to another.

Restriction on to: owl:cardinality 1
A conversion MUST have exactly 1 units:to property.

Unit

Class

Label	Unit
In domain of	conversion
	prefixConversion
	render
	symbol
In range of	to
	unit

A unit for a control value.

Properties

conversion

Property

Label	conversion
Domain	Unit
Range	Conversion
Type	Object Property

A conversion from this unit to another.

factor

Property

Label	conversion factor
Domain	Conversion
Type	Datatype Property

The factor to multiply the source value by in order to convert to the target unit.

prefixConversion

Property

Label	prefix conversion
Sub-property of	conversion
Domain	Unit
Range	Conversion
Type	Object Property

A conversion from this unit to another with the same base but a different prefix.

render

Property

Label	unit format string
Domain	Unit
Range	xsd:string
Type	Datatype Property

A printf format string for rendering a value (e.g., "%f dB").

symbol

Property

Label	unit symbol
Domain	Unit
Range	xsd:string
Type	Datatype Property

The abbreviated symbol for this unit (e.g., "dB").

to

Property

Label	conversion target
Domain	Conversion
Range	Unit
Type	Object Property

The target unit this conversion converts to.

unit

Property

Label	unit
Range	Unit
Type	Object Property

The unit used by the value of a port or parameter.

Instances

bar

Instance

Label	bars
Type	Unit
render	%f bars
symbol	bars

Musical bars or measures.

beat

Instance

Label	beats
Type	Unit
render	%f beats
symbol	beats

Musical beats.

bpm

Instance

Label

beats per minute

Type

prefixConversion

factor	0.0166666666
to	hz

%f BPM

BPM

Beats Per Minute (BPM), the standard unit for musical tempo.

cent

Instance

Label

cents

Type

factor	0.01
to	semitone12TET

%f ct

ct

Cents (hundredths of semitones).

cm

Instance

Label

centimetres

Type

factor	0.3937
to	inch

prefixConversion

factor	0.01
to	m

prefixConversion

factor	10
to	mm

prefixConversion

factor	0.00001
to	km

%f cm

cm

Centimetres (hundredths of metres).

coef

Instance

Label

coefficient

Type

factor	100
to	pc

* %f

A scale coefficient where 1 is unity, or 100 percent.

db

Instance

Label	decibels
Type	Unit
render	%f dB
symbol	dB

Decibels, a logarithmic relative unit where 0 is unity.

degree

Instance

Label	degrees
Type	Unit
render	%f deg
symbol	deg

An angle where 360 degrees is one full rotation.

frame

Instance

Label	audio frames
Type	Unit
render	%f frames
symbol	frames

Audio frames or samples.

hz

Instance

Label

hertz

Type

prefixConversion

factor	0.001
to	khz

prefixConversion

factor	0.000001
to	mhz

%f Hz

Hz

Hertz, or inverse seconds, the SI derived unit for frequency.

inch

Instance

Label

inches

Type

factor	0.0254
to	m

%f"

in

An inch, defined as exactly 0.0254 metres.

khz

Instance

Label

kilohertz

Type

prefixConversion

factor	1000
to	hz

prefixConversion

factor	0.001
to	mhz

%f kHz

kHz

Kilohertz (thousands of Hertz).

km

Instance

Label

kilometres

Type

factor	0.62138818
to	mile

prefixConversion

factor	1000
to	m

prefixConversion

factor	100000
to	cm

prefixConversion

factor	1000000
to	mm

%f km

km

Kilometres (thousands of metres).

m

Instance

Label

metres

Type

factor	39.37
to	inch

prefixConversion

factor	100
to	cm

prefixConversion

factor	1000
to	mm

prefixConversion

factor	0.001
to	km

%f m

m

Metres, the SI base unit for length.

mhz

Instance

Label

megahertz

Type

prefixConversion

factor	1000000
to	hz

prefixConversion

factor	0.001
to	khz

%f MHz

MHz

Megahertz (millions of Hertz).

midiNote

Instance

Label	MIDI note
Type	Unit
render	MIDI note %d
symbol	note

A MIDI note number.

mile

Instance

Label

miles

Type

factor	1609.344
to	m

%f mi

mi

A mile, defined as exactly 1609.344 metres.

min

Instance

Label

minutes

Type

factor	60.0
to	s

%f mins

min

Minutes (60s of seconds and 60ths of an hour).

mm

Instance

Label

millimetres

Type

factor	0.03937
to	inch

prefixConversion

factor	0.001
to	m

prefixConversion

factor	0.1
to	cm

prefixConversion

factor	0.000001
to	km

%f mm

mm

Millimetres (thousandths of metres).

ms

Instance

Label

milliseconds

Type

prefixConversion

factor	0.001
to	s

%f ms

ms

Milliseconds (thousandths of seconds).

oct

Instance

Label

octaves

Type

factor	12.0
to	semitone12TET

%f octaves

oct

Octaves, relative musical pitch where +1 octave doubles the frequency.

pc

Instance

Label

percent

Type

factor	0.01
to	coef

%f%%

%

Percentage, a ratio as a fraction of 100.

s

Instance

Label

seconds

Type

factor	0.0166666666
to	min

prefixConversion

factor	1000
to	ms

%f s

s

Seconds, the SI base unit for time.

semitone12TET

Instance

Label

semitones

Type

factor	0.083333333
to	oct

%f semi

semi

A semitone in the 12-tone equal temperament scale.