YOVISTO - Academic Video Search

Abstract

Linked Open Data has become one of the driving forces for the emerging Semantic Web, which enables interlinking and integrating former proprietary data to the global linked data by using RDF as a standard data format. We have published the database of yovisto.com in RDF and made it accessible via SPARQL.

This page specifies the yovisto ontology and shows some examples on how to use this ontology with our SPARQL endpoint.

OWL-DL Ontology: http://www.yovisto.com/ontology/0.9/index.owl

SPARQL-Endpoint: http://sparql.yovisto.com/

Further information:

Overview

Namespaces


The following namespaces are used:

Prefix	URI	Comment
yo	http://www.yovisto.com/ontology/0.9/	the yovisto base ontology
foaf	http://xmlns.com/foaf/0.1/	the friend of a friend namespace [more info]
owl	http://www.w3.org/2002/07/owl#	the Web Ontology Language [more info]
dc	http://purl.org/dc/elements/1.1/	Dublin Core Metadata Element Set, Version 1.1 - the Dublin Core ontology [more info]
dcterms	http://purl.org/dc/terms/	DCMI Metadata Terms - the Dublin Core ontology with element refinements [more info]
rdf	http://www.w3.org/1999/02/22-rdf-syntax-ns#	the RDF base namespace [more info]
rdfs	http://www.w3.org/2000/01/rdf-schema#	the RDFSchema namespace [more info]
tag	http://www.holygoat.co.uk/owl/redwood/0.1/tags/	the tag/tagging ontology [more info]
mpeg7	http://rhizomik.net/ontologies/2005/03/Mpeg7-2001.owl#	the mpeg7 ontology [more info]
skos	http://www.w3.org/2008/05/skos#	the Simple Knowledge Organization System, a common data model for sharing and linking knowledge organization systems [more info]

Classes

Category:

Every video collection usually belongs to a category, as e.g., Computer Science or Physics. You can find an overview on yovisto's categories here.

Constraint	Property
exactly 1	dc:identifier
exactly 1	dc:title
maximal 1	skos:related

Collection:

A collection is a series of videos (videofiles) or a Podcast consisting of episodes. A collection also represents a lecture series consisting of several classes.

Collection is a part of Category.

Constraint	Property
exactly 1	dc:identifier
	dc:title
	dc:creator	all values from Organization
maximal 1	dc:subject	all values from Category
maximal 1	dc:coverage

Video

A video is a digital asset, e.g., a lecture recording.

Constraint	Property
exactly 1	dc:identifier
	dc:title
	dcterms:extent
	dcterms:isPartOf	only Collection
maximal 1	dc:subject	all values from Category
	dc:coverage
	dc:description
	dc:format
	dc:language
	dcterms:alternative
minimal 1	dc:contributer	all values from Speaker
minimal 0	mpeg7:MediaTime

VideoSegment:

A videosegement is a part of a video. Videosegments are examined with scene detection algorithms specialized on lecture recordings automatically.

VideoSegment is a part of exactly 1 Video.

Constraint	Property
exactly 1	dcterms:isPartOf	only Video
exactly 1	mpeg7:MediaTime
maximal 1	dc:description
maximal 1	dc:title

MediaTimeType:

The MediaTimeType specifies any time intervall in a video. Usually, a MediaTimeType has a start time point and a duration. MediaTimeType is used to specify the time reference of video segments and tags in a certain video. See also: mpeg-7 ontology

MediaTimeType is a part of the mpeg7 ontology.

Constraint	Property
Multiple	mpeg7:MediaTimePoint
	mpeg7:duration
	tag:tag	all values from Tagging

Tagging:

Tagging describes the process when a user tags a video. See also: tag ontology

Tagging is a part of the tag ontology.

Constraint	Property
Multiple	tag:associatedTag
exactly 1	tag:taggedBy	all values from User

Tag:

Usage Examples

Hints:

The classes Video and VideoSegment are linked over the property mpeg7:MediaTime to mp7:MediaTimeType
which has two properties: mp7:MediaTimePoint and mp7:duration.

Because of the allocation of tags just for a special segment in one video these segments are distinguished with these information.
So the mp7:MediaTimePoint tags the startpoint of this segment and the mp7:duration tags the duration
how long the segment is on and the tag is valid in one video.

Although Video keeps the property dcterms:extent which only means the duration of the whole video. Don't confuse it with mp7:duration!

Examples:

The following example shows a SPARQL query which delivers the 10 most assigned tags in yovisto:

				
PREFIX tag: <http://www.holygoat.co.uk/owl/redwood/0.1/tags/>
PREFIX mpeg7: <http://rhizomik.net/ontologies/2005/03/Mpeg7-2001.owl#>

SELECT ?name, COUNT(*) FROM <http://www.yovisto.com>
WHERE {
  ?video mpeg7:MediaTime ?mediaTimeType .
  ?mediaTimeType tag:tag ?tagging .
  ?tagging tag:associatedTag ?tag .
  ?tag tag:name ?name .
}
GROUP BY ?name
ORDER BY DESC 2
LIMIT 10

[execute query]

And similar to the query above you can search for all videos which are tagged with "ipv6":

				
PREFIX tag: <http://www.holygoat.co.uk/owl/redwood/0.1/tags/>
PREFIX mpeg7: <http://rhizomik.net/ontologies/2005/03/Mpeg7-2001.owl#>

SELECT ?video FROM <http://www.yovisto.com>
WHERE {
  ?video mpeg7:MediaTime ?mediaTimeType .
  ?mediaTimeType tag:tag ?tagging .
  ?tagging tag:associatedTag ?tag .
  ?tag tag:name "ipv6" .
}

[execute query]

This query delivers all videos and their titles which belong to the category "Biology":

				
PREFIX dc: <http://purl.org/dc/elements/1.1/>

SELECT ?video, ?title FROM <http://www.yovisto.com>
WHERE {
  ?video dc:subject ?category ;
    dc:title ?title .
  ?category dc:title "Biology" .
}

[execute query]

Description of yovisto ontology

Abstract

Table of Content

Overview

Namespaces

Classes

Usage Examples

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