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Media Annotations Working Group Publishes Drafts

Posted by Brian Sletten on Mar 30, 2010

Sections: Enterprise Architecture,; Architecture & Design
Topics: Semantic Web ,; W3C ,; Architecture ,; Specifications ,; Ontology ,; Dublin Core ,; RDFa

The W3C Media Annotations Working Group has recently posted drafts of its Ontology for Media Resource 1.0 and API for Media Resource 1.0 efforts. They have also updated the Use Cases document to reflect some of the intentions of these projects.

The basic goal of the Working Group is to produce an API and domain model for handling the explosion of media content on the Web. There is not and never will be a single set of audio and video formats used by all residents of the Internet, so they felt the need to establish a mechanism for describing this content and connecting it to other content of different formats. Leveraging the power of Semantic Web technologies, they want to be able to do things such as:

Retrieve media metadata in a common form, even if it is stored differently in different formats
Define a mapping between the metadata supported by the source formats
Manage user-specified metadata for the media resources (e.g. reviews, ratings, tagging)
Handle structured annotations from the various sources

The drafts support twenty-five different formats including Cable Labs's Video-On-Demand formats, Dublin Core publication metadata, the exchangeable image file format (EXIF) for digital camera, Digital Bazaar's Video Metadata, MPEG ID3 tags, QuickTime, Adobe's XMP, YouTube's Data API Protocol, etc.

The ontology reuses many terms from popular vocabularies such as Dublin Core, but wanted to define its key ideas in its own terminology. The draft not only defines these terms, but also specifies a one-way mapping into the metadata and annotations of the native formats.

The properties include terms such as:

Name	Description
ma:identifier	URI for the resource
ma:title	Title of the resource
ma:language	BCP 47 language used in the resource
ma:locator	URL associated with the content
ma:creator	A primary author of the content
ma:contributor	A contributing agent to the content
ma:location	Where resource was filmed or recorded
ma:createDate	Date/time of creation
ma:keyword	Tags associated with the content
ma:description	A short textual description of the resource
ma:genre	Genre associated with the resource (pref. EBU)
ma:copyright	Description of the copyright associated with the resource
ma:publisher	Person or organization responsible for publishing the content
ma:compression	Compression codecs used
ma:duration	Duration (in s)
ma:samplingrate	Audio sampling rate (in sps)
ma:framerate	Video frame rate (in fps)
ma:bitrate	Average bit rate (in kpbs)

Not every property maps to every format, but where there is overlap it should be possible to handle disparate content similarly to make it easier for people to find and describe these files. As an example, the "ma:creator" property maps to the "com.apple.quicktime.author" property in QuickTime, "dc:creator" in Dublin Core and "media:credit@role" in the YouTube Data API. Because of subtleties between the intended meanings of the different properties, it is not currently possible to map between the different formats, only to the common terminology.

The API being defined is intended to manage these mappings and provide a common programming model for interacting with the content so that format-specific code is not required. The API can be used by either client or server-side code as suggested by the two different scenarios depicted here:

Scenarios for the Media Annotation Working Group Specifications

Original source: http://www.w3.org/TR/2010/WD-mediaont-api-1.0-20100309/API_options.png

Additionally, there are several Candidates for Additional Elements being considered by the Working Group for inclusion in the specification.

This is very much a work in progress, but shows promising signs of producing useful abstractions and working code for managing the commonalities between these and potentially other media formats.