Use Cases and Requirements for Ontology and API for Media Resource 1.0

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WonSuk Lee, Electronics and Telecommunications Research Institute (ETRI)
Tobias Bürger, University of Innsbruck
Felix Sasaki, Potsdam University of Applied Sciences
Véronique Malaisé, VU University of Amsterdam


This document specifies use cases and requirements as an input for the development of the "Ontology for Media Resource 1.0" and the "API for Media Resource 1.0". The ontology will be a simple ontology to support cross-community data integration of information related to media resources on the Web. The API will provide read access and potentially write access to media resources, relying on the definitions from the ontology.

The main scope of this document are videos. Metadata for other media resources like audio or images will be taken into account if it is applicable for videos as well.

Status of this Document

Table of Contents

1 Introduction
2 Purpose of this draft publication
3 Purpose of the Ontology and the API
4 Terminology
5 Use Cases
    5.1 Interoperability between media resources across Cultural Heritage Institutions
    5.2 Recommendation across different media types
    5.3 Life Log
    5.4 Access via web client to metadata in heterogeneous formats
    5.5 User generated Metadata
    5.6 Use cases: to be done
6 Requirements
    6.1 Requirement r01: Providing methods for getting metadata information stored in different formats
    6.2 Requirement r02: Providing methods for setting metadata information stored in different formats
    6.3 Requirement r03: Providing in the API a means for supporting structured annotations
    6.4 Requirement r04: Providing a means to access user-defined metadata
    6.5 Requirement r05: Providing the ontology as a simple set of properties
    6.6 Requirement r06: Specifying an internal or external format for the ontology
    6.7 Requirement r07: Introducing several abstraction levels in the ontology
    6.8 Requirement r08: Being able to apply the ontology / API for collections of metadata
    6.9 Requirement r09: Supporting the provenance information of metadata properties
    6.10 Requirement r10: Being able to describe fragments of media resources
    6.11 Requirement r11: Providing the ontology in slices of conformance
    6.12 Requirement r12: Providing support for controlled vocabularies for the values of different properties
    6.13 Requirement r13: Allowing for different return types for the same property
    6.14 Requirement r14: Providing support for policy information
    6.15 Requirement r15: Providing support for discovery of named and track fragments


A References
B References (Non-Normative)
C Change Log (Non-Normative)
D Acknowledgements (Non-Normative)

1 Introduction

Anticipating the increase in online video and audio in the upcoming years, we can foresee that it will become progressively more difficult for viewers to find the content using current search tools. In addition, video services on the web that allow for upload of video, need to display selected information about the media documents which could be facilitated by a uniform access to selected metadata across a variety of file formats.

Unlike hypertext documents, it is more complex and sometimes impossible to deduce meta information about a medium, such as its title, author, or creation date from its content. There has been a proliferation of media metadata formats for the document's authors to express this metadata information. For example, an image could potentially contain EXIF, IPTC and XMP information. There are also several metadata solutions for media related content, including MPEG-7, Yahoo! MEDIA RSS, Google Videositemaps, VODCSV, TVAnytime and EBU P-Meta. Many of these formats have been extensively discussed in the deliverables XGR Vocabularies and XGR Image Annotation of the W3C Multimedia Semantics Incubator Group , which provide a major input to this Working Group.

The "Ontology for Media Resource 1.0" will address the intercompatiblity problem by providing a common set of properties to define the basic metadata needed for media resources and the semantic links between their values in different existing vocabularies. It will help circumventing the current proliferation of video metadata formats by providing full or partial translation and mapping from properties in formats to a common set of properties in the ontology. The ontology will be accompanied by an API that provides uniform access to all elements defined by the ontology.

This document specifies the use cases and requirements that are motivating the development of the "Ontology for Media Resource 1.0". The scope is mainly video media resources, but we take also other media resources into account if their metadata information is related to video.

The development of the requirements has three major inputs: Use cases, analysis of existing standards, and a description of canonical media processes.

2 Purpose of this draft publication

This initial version of this document contains only a small set of use cases and requirements. Nevertheless it is being published to gather wide feedback on the general direction of the Working Group. Hence, we would like to encourage especially feedback on 6 Requirements, the requirements which we are planning to implement, or others which we are planning not to take into account.

Currently, there is an additional section under development, describing a top-down modeling approach to describe the media annotation problem. The Working Group is considering to publish that section in an updated version of this document.

3 Purpose of the Ontology and the API

The following figure visualizes the purpose of the ontology, the purpose of the API and their relation to applications.

Purpose of the ontology and the API

The ontology will define mappings from properties in formats to a common set of properties. The API then will define methods to access heterogeneous metadata, using such mappings. An example: the property createDate from XMP XMP can be mapped to the property DateCreated from IPTC IPTC.

An important aspect of the above figure is that everything visualized above the API is left to applications. For example.

The ontology and the API provide merely a basic, simple means of interoperability for such applications.

4 Terminology

The keywords MUST, MUST NOT, SHOULD and SHOULD NOT are to be interpreted as defined in RFC 2119.

5 Use Cases

5.1 Interoperability between media resources across Cultural Heritage Institutions

Summary: Accessing media collections of different cultural heritage institutions (libraries, museums, archives, etc.) on the Web.

Related requirements:

Description / Example:

The collections of cultural heritage institutions (libraries, museums, archives, etc.) are increasingly digitised and made available on the Web. These collections range from text to image, video and audio (music and radio collections, for example). A comprehensive, professionally created documentation is usually available, however, often using domain specific or even proprietary metadata models. This hinders accessing these collections in an homogeneous or centralized way and linking them across collections.

For example, Jane is a TV journalist searching for material about some event in contemporary history. She is interested in television and radio broadcasts from this event, along with photos and newspaper articles. All these resources come from different collections, and some are in different languages. A homogeneous way of accessing them across the Web would improve her work.

5.2 Recommendation across different media types

Summary: Accessing heterogeneous media resources metadata as the input to the creation of recommendations which is based on user preferences.

Related requirements:

Description / Example:

People nowadays are able to enjoy large number of programs from different content providers (broadcasting companies, Internet video website, etc.). To achieve better user experience, reduce the user's experience of being overloaded, and hence retain users, some systems provide recommendations based on the user's history, ratings, or stated preferences. However, different content providers usually have their specific or proprietary metadata models, which is one of the key problems faced by recommendation service providers. A common ontology spanning different metadata sets can allow recommendation systems to return a better, larger, and more relevant selection than when the metadata systems are unrelated.

Company A is an IPTV add-value service provider. One of their services is to recommend programs that users might like, based on their watching history or explicit rating of programs. In this system, users are able to watch regular TV programs with electronic program guide (EPG) format metadata, videos such as from YouTube, with website-specific metadata, etc. In order to perform uniform and effective recommendation in the absence of a common set of vocabularies, they would need to design own integrated media annotation model.

5.3 Life Log

Use case summary: combining heterogeneous metadata from life logs, to allow searching personal life log information, potentially enriched with geolocation information.

Related requirements:

Description / Example:

With modern devices, a person can capture his or her experience, including all sorts of daily events, by creating images, audios and videos files, and publish them on the Web. These are called "Life Logs". These Life Logs contain various information such as time, location, creator's profile, relations between different people, and even emotion. If accessed via an ontology providing links between the different metadata used to describe these various information, a user could easily and efficiently search for his or her personal Life Log information, including emotional information ( this type of information can be described using a vocabulary like Emotions ML 1.0), or geolocation information on the Web (which can be described using the Geolocation API specification). Other people's Life Logs contents could also be searched and accessed via this ontology.

5.4 Access via web client to metadata in heterogeneous formats

Use case summary: Accessing metadata in heterogeneous formats for web developers

Related requirements:

Description / Example:

John is developing a JavaScript library for accessing metadata of media resources (e.g. video) in various formats. These resources are available within a database, such as that of a search engine indexing the internet or other web-accessible content (e.g. a corporate repository, library, etc.). His library can be used to make queries of the media resources like:

  • "Find me all media resources which have been created by a specified person"

  • "Find me all media resources which have been created this year"

  • "Find me all videos which are not longer than a specified time"

  • "Extract all user added tags from all media resources available"

This use case is related to many other use cases. Nevertheless it is mentioned separately since, at the difference from other requirements, its implementation requires only a small set of requirements. The difference from this use case to the Cultural Heritage use case is that the former is very strongly tied to the requirement of a read-only client side API.

5.5 User generated Metadata

Use case summary: Adding or linking to external metadata by different users.

Related requirements:

Description / Example:

John wants to publish comments on the last movies he has seen on http://example.cheap-vod.com/ . For each movie, he uses the description metadata field to provide a personal summary of the movie (with incentive to see or avoid the movie according to his own opinions), and the ranking metadata. John is also not satisfied with the genre classification of the website, so he uses the genre metadata field to provide his appreciation of the genre with regard to a better scheme. He then publishes these metadata on his blog (may be in the form of a podcast), but only links to the videos themselves.

Jane, a friend of John's and another cheap-vod customer, can now configure her cheap-vod account or her browser, to have John's metadata added to or replacing the original metadata embedded in each file.

Now Jane wants to study more particularly the characters of the movie. For making this easier, she defines one custom metadata field for each of the main characters, and sets these fields to "yes" or "no" for each sequence, to indicate if they contain that character or not. For example:

dc:title "Meeting Tom Baxter" ;
dc:description "Cecilia sees the movie several times when...." ;
custom:cecilia "yes" ;
custom:tom "yes" ;
custom:gil "no" ;
custom:monk "no".

In this context, the ontology would enhance the interoperability between different users.

5.6 Use cases: to be done

Editorial note 
In a future draft of this document, the following use cases will be spelled out separately, integrated into existing use cases or dropped.

6 Requirements

This sections describes requirements for the ontology and the API. The Working Group has agreed to implement the following requirements. For the other requirements, there is no agreement yet, and the Working Group is asking reviewers of this document for feedback about their implementation.

The requirements which the Working Group currently does not have agreement to take into account are the following:

6.4 Requirement r04: Providing a means to access user-defined metadata

Description: It MUST be possible to access user-defined metadata to media resources. "user-defined metadata" means metadata that is not defined in a standardized format, but which is being created entirely by the user.

Rationale: The ability to access user-defined metadata is necessary for the use case user generated metadata.

Target (API and / or ontology): API which needs to provide a method to add user-defined metadata, and the ontology which needs to provide an extensibility mechanism.


"Accessing user-defined metadata" may mean setting or getting such metadata. We have not decided whether we will be able to support the process of setting metadata, see issues mentioned at Requirement r02: Providing methods for setting metadata in media resources in different formats.

6.7 Requirement r07: Introducing several abstraction levels in the ontology

Description: The ontology MUST provide several abstraction levels.

Rationale: Several metadata standards like FRBR or CIDOC allow referring to multimedia resources on several abstraction levels, in order to separate e.g. a movie, a DVD which contains the movie and a specific copy of the DVD. Especially for collections of multimedia resources, knowledge about such abstraction levels is helpful, as a means for accessing the resources on each level.

Target (API and / or ontology): ontology and potentially API, if we want to provide access to metadata and multimedia resources on several abstraction levels.

6.15 Requirement r15: Providing support for discovery of named and track fragments

Description: The ontology MUST provide properties to query the list tracks that exist in a media resource as well as the list of named fragments.

Rationale: The Media Fragments WG is interested in technologies that enable track and named fragments discovery, i.e., the UA needs a way to know for which tracks are available in a particular media resource, and which named fragments have been annotated.

Source: Input from Media Fragments WG

Target (API and / or ontology): Ontology and API

A References

[RFC 2119]
S. Bradner. Key Words for use in RFCs to Indicate Requirement Levels. IETF RFC 2119, March 1997. Available at http://www.ietf.org/rfc/rfc2119.txt.

B References (Non-Normative)

N. Crofts, M. Doerr, T. Gill, S. Stead, M. Stiff. Definition of the CIDOC Conceptual Reference Model, Version 5.0. Technical specification December 2008. Available at http://cidoc.ics.forth.gr/docs/cidoc_crm_version_5.0_Dec08.pdf.
[EBU P-Meta]
EBU-P Metadata European Broadcasting Union specification 2007. Available at http://tech.ebu.ch/docs/tech/tech3295v2.pdf.
[EBU Core]
EBU CORE European Broadcasting Union specification 2008. Available at http://tech.ebu.ch/docs/tech/tech3293-2008.pdf.
[Emotions ML 1.0]
P. Baggia, F. Burkhardt. J. C. Martin, C. Pelachaud, C. Peter, B. Schuller, I. Wilson and E. Zovato. Elements of an EmotionML 1.0 . W3C Incubator Group Report 20 November 2008 . Available at http://www.w3.org/2005/Incubator/emotion/XGR-emotionml-20081120/.
Exchangeable image file format for digital still cameras: Exif Version 2.2. JEITA Technical specification August 2002. Available at http://www.digicamsoft.com/exif22/exif22/html/exif22_1.htm.
Functional Requirements for Bibliographic Records - Final Report. Technical specification 1998. Available at http://archive.ifla.org/VII/s13/frbr/frbr.htm.
[Geolocation API]
A. Popescu. Geolocation API Specification. W3C Working Draft 22 December 2008. Available at http://www.w3.org/TR/2008/WD-geolocation-API-20081222/. The latest version of the Geolocation API specification is available at http://www.w3.org/TR/geolocation-API/ .
IPTC Standard Photo Metadata 2008. IPTC Core Specification Version 1.1, IPTC Extension Specification Version 1.0, Document Revision 2, June 2008. Available at http://www.iptc.org/std/photometadata/2008/specification/IPTC-PhotoMetadata-2008.pdf
Yahoo! Media RSS Module - RSS 2.0 Module. Technical specification March 2008. Available at http://search.yahoo.com/mrss.
Information Technology - Multimedia Content Description Interface (MPEG-7). Standard No. ISO/IEC 15938:2001, International Organization for Standardization(ISO), 2001.
R. Lannella, Open Digital Rights Language (ODRL) Version 1.1. W3C Note 19 September 2002. Available at http://www.w3.org/TR/odrl/
Platform for Privacy Preferences (P3P) Project. Available at http://www.w3.org/P3P/
TV-Anytime The specifications and schemas can be downloaded free of charge from http://www.etsi.org/WebSite/Standards/StandardsDownload.aspx .
Google Video Sitemap. Example available at http://www.google.com/support/webmasters/bin/answer.py?answer=80472&topic=10079 .
Video-On-Demand Content Specification Version 2.0. CableLabs technical specification January 2007. Available at http://www.cablelabs.com/specifications/MD-SP-VOD-CONTENT2.0-I02-070105.pdf.
[XGR Image Annotation]
M. Hausenblas. Multimedia Vocabularies on the Semantic Web. W3C Incubator Group Report 24 July 2007. Available at http://www.w3.org/2005/Incubator/mmsem/XGR-vocabularies-20070724/.
[XGR Vocabularies]
R. Troncy, J. v. Ossenbruggen, J. Z. Pan and G. Stamou. Image Annotation on the Semantic Web. W3C Incubator Group Report 14 August 2007. Available at http://www.w3.org/2005/Incubator/mmsem/XGR-image-annotation-20070814/.
XML TV Project. Available at http://wiki.xmltv.org/index.php/XMLTVProject.
XMP Specification Part 2 - Standard Schemas. Technical specification, Adobe 2008. Available at http://www.adobe.com/devnet/xmp/pdfs/XMPSpecificationPart2.pdf .

C Change Log (Non-Normative)

2009-01-19Initial publication.
2009-03-16Integrated comments from the Media Fragments Working Group, and Raphaël Troncy. See editing summary.
2009-03-16Editing of the Cultural Heritage Institutions use case.
2009-03-19Integrated comments from Jean-Pierre Evain.
2009-04-02Removed the mobile use case.
2009-04-29Integrated comments from David Singer, except the "More structural comments".
2009-04-29Added a health warning to the status section about ongoing terminology discussions.
2009-12-24Added r14 and r15 to 6 Requirements.
2009-12-24Revised r09 with concrete description.
2009-12-24Changed the term of Media Object with Media Resource.

D Acknowledgements (Non-Normative)

This document is the work of the W3C Media Annotations Working Group.

Members of the Working Group are (at the time of writing, and by alphabetical order): Werner Bailer (JOANNEUM RESEARCH), Tobias Bürger (University of Innsbruck), Eric Carlson (Apple, Inc.), Pierre-Antoine Champin ((public) Invited expert), Ashish Chawla ((public) Invited expert), Jaime Delgado (Universitat Politècnica de Catalunya), Jean-Pierre EVAIN ((public) Invited expert), Philip Jägenstedt (Opera Software), Ralf Klamma ((public) Invited expert), WonSuk Lee (Electronics and Telecommunications Research Institute (ETRI)), Véronique Malaisé (Vrije Universiteit), Erik Mannens (IBBT), Hui Miao (Samsung Electronics Co., Ltd.), Thierry Michel (W3C/ERCIM), Frank Nack (University of Amsterdam), Soohong Daniel Park (Samsung Electronics Co., Ltd.), Silvia Pfeiffer (W3C Invited Experts), Chris Poppe (IBBT), Víctor Rodríguez (Universitat Politècnica de Catalunya), Felix Sasaki (Potsdam University of Applied Sciences), David Singer (Apple, Inc.), Florian Stegmaier ((public) Invited expert), John Strassner ((public) Invited expert), Joakim Söderberg (ERICSSON), Thai Wey Then (Apple, Inc.), Ruben Tous (Universitat Politècnica de Catalunya), Raphaël Troncy (CWI), Vassilis Tzouvaras (K-Space), Davy Van Deursen (IBBT).

The people who have contributed to discussions on public-media-annotation@w3.org are also gratefully acknowledged.