@prefix bioregistry: .
@prefix bioregistry.metaresource: .
@prefix bioregistry.schema: .
@prefix dcat: .
@prefix dcterms: .
@prefix foaf: .
@prefix rdfs: .
@prefix skos: .
@prefix tib.ts: .
@prefix xsd: .
bioregistry.metaresource:bioregistry dcterms:hasPart bioregistry:tib.ac .
bioregistry.metaresource:tib dcterms:hasPart tib.ts:ac .
bioregistry:tib.ac a bioregistry.schema:0000001 ;
rdfs:label "The Audio Commons Ontology" ;
dcterms:description """The Audio Commons Ontology has been created in the context of the European project [Audio Commons](https://www.audiocommons.org/), which were aimed at favouring sharing and reuse of audio content (both of musical and non-musical nature), specially using [Creative Commons](https://creativecommons.org/) licenses.
It is designed specifically to integrate access to multiple heterogeneously structured audio content providers. In particular the following ones have been considered in the project:
- [Freesound](https://freesound.org/), a collaborative database of Creative Commons Licensed sounds;
- [Jamendo](https://www.jamendo.com/), a music website for independent artists;
- [Europeana Sounds](https://www.eusounds.eu/), a European project collecting and sharing data from several archives of sounds and sound-related media;
- [Internet Archive](https://archive.org/), a non-profit library of millions of freely accessible media contents.
### The base model
The Audio Commons ontology is based on [Functional Requirements for Bibliographic Records (FRBR)](https://en.wikipedia.org/wiki/Functional_Requirements_for_Bibliographic_Records), a bibliographic model designed for user tasks of retrieval and access in online library catalogues and bibliographic databases. FRBR distinguish the products of intellectual or artistic endeavor in four main classes: work, expression, manifestation, item. It is available as RDF vocabulary at https://vocab.org/frbr/core. For further information on FRBR, check the [standard](https://repository.ifla.org/handle/123456789/811).
Another important model related to audio is the [Music Ontology](http://musicontology.com/), which is also based on the FRBR model. Our ontology is more generic than the Music Ontology but is interoperable with it to support the specificities of music-related audio content.
The Audio Commons ontology works also in conjunction with
- [Dublin Core](https://www.dublincore.org/specifications/dublin-core/dcmi-terms/) for basic metadata,
- [EBU Core](https://www.ebu.ch/metadata/ontologies/ebucore/) for technical properties of audio files,
- [SKOS](https://www.w3.org/TR/skos-primer/) to support taxonomic classifications,
- [Creative Commons Licensing schema](https://creativecommons.org/ns) to represent media licensing,
- [Event ontology](http://motools.sf.net/event/event.html) for the formalisation of events,
- [Audio Features Ontology](https://w3id.org/afo/onto/) for the characterisation of audio features.
### Ontology overview
The figure above shows the most general classes and properties of the Audio Commons ontology and their relationship with classes of the FRBR and the Music Ontology:
- **`ac:AudioExpression`**, the specific intellectual or artistic form that a work takes each time it is _realised_, in the audio domain, e.g., the recording or synthesis of music or sounds;
- **`ac:AudioManifestation`**, the physical embodiment of an audio expression, e.g., a musical track, a sound, an album;
- **`ac:AudioItem`**, a single exemplar of an audio manifestation, e.g., a copy of a CD or a specific media file.
The FRBR class Work, representing a distinct intellectual or artistic creation on a more conceptual level, has not been specialised in Audio Commons.
The Audio Commons ontology provides a generic schema for audio classification through the property **`ac:audioCategory`** that associates any audio expression, manifestation, or item to some generic **`ac:AudioCategory`**. These two terms can be specialised to provide spefic categorisations.
### Manifestations: audio clips and collections
The figure above shows classes and properties related to audio manifestations. An instance of **`ac:AudioClip`**, a subclass of `ac:AudioManifestation`, is any audio segment that has been published in some form or uploaded for consumption, for example, a track in a music label's repository or a sound in an audio repository, library or archive.
The class **`ac:AudioCollection`**, another subclass of `ac:AudioManifestation`, is used to represent collections of audio clips. The class **`ac:AudioCollectionNode`** is used to represent single nodes of a collection, offering local information like the index in the collection and pointers to previous and next nodes. The separation between the collection node and its actual content (e.g., an `ac:AudioClip`) permits the same content to be shared in multiple collections.
The content of each node of a collection is not limited to an `ac:AudioClip`, but may contain any `ac:AudioManifestation`. Collections can thus contain other collections to support specific cases, e.g. a mapping to the Music Ontology model where an `mo:Release` can contain multiple `mo:Record`(s) that can in turn contain multiple `mo:Track`(s).
### Items: audio files
An `ac:AudioItem` is a concrete exemplar of an audio manifestation. In our domain, the main exemplars are the actual audio files.
The corresponding class **`ac:AudioFile`** is a subclass of `ac:AudioItem`. It is subclass of `ebu:MediaResource` too and the corresponging properties of EBU Core can be used to describe the file (e.g., `ebu:hasEncodingFormat`, `ebu:fileSize`).
### Expressions: audio signals
While `ac:AudioFile` represents a concrete file encoded in a certain format, **`ac:DigitalSignal`** is the representation of the corresponding digital signal. `ac:DigitalSignal` is a subclass of `ac:MusicalExpression`.
The data properties `ac:sampleRate`, `ac:bitsPerSample`, and `ac:channels`, associate a signal with its basic features specific to digital representations.
The property `ac:publicationOf` can be used to associate an `ac:AudioClip` with the corresponding digital signal. The property `ac:encodes` instead, associates an `ac:AudioFile` with the encoded digital signal.
### Events: recording/syntesis
The description of temporal events is crucial to formalise and document transitions in the workflow of audio production and publication. The class `event:Event` of the Event Ontology is thus specialised for specific actions that are interesting for the audio domain.
Using the `event:Event` class, details of an event such as its location in time and space, its factor and its products may be explicitly described. Moreover, events can be composed using the property `event:sub_event`, to build complex events.
The class `ac:SignalProduction` represents the act of producing a `ac:Signal`, which could be either an `ac:AnalogSignal` or a `ac:DigitalSignal`. This is complemented by **`ac:Recording`**, representing the process of recording a sound (`ac:Sound`) or the product of **`ac:Synthesis`**, in case of artificially generated sounds.
### Events (continued): publication
The event **`ac:AudioPublication`** represents the public release of a piece of work, e.g., the release of a new album by a band.
### Usage Example
The figure above shows an example of use of the Audio Commons ontology to represent a sound from the Freesound database. For simplicity only the classes `ac:AudioClip`, `ac:AudioFile`, and `ac:AudioCategory` are used in this case."""^^xsd:string ;
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skos:exactMatch tib.ts:ac ;
dcat:keyword "engineering",
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foaf:homepage ;
bioregistry.schema:0000005 "AnalogSignal"^^xsd:string ;
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bioregistry.schema:0000024 "https://w3id.org/ac-ontology/aco#"^^xsd:string ;
bioregistry.schema:0000027 ;
bioregistry.schema:0000029 "tib.ac" .
tib.ts:ac dcterms:isPartOf bioregistry.metaresource:tib .