W3C

API for Media Resources 1.0

W3C Candidate Recommendation 22 November 2011

This version:
http://www.w3.org/TR/2011/CR-mediaont-api-1.0-20111122/
Latest published version:
http://www.w3.org/TR/mediaont-api-1.0/
Previous version:
http://www.w3.org/TR/2011/WD-mediaont-api-1.0-20110712/
Editors:
Florian Stegmaier, University of Passau
이원석(Wonsuk Lee), Samsung Electronics, Ltd.
Chris Poppe, Ghent University
Werner Bailer, JOANNEUM RESEARCH

Abstract

This specification defines an API to access metadata information related to media resources on the Web. The overall purpose is to provide developers with a convenient access to metadata information stored in different metadata formats. The API provides means to access the set of metadata properties defined in the Ontology for Media Resources 1.0 specification. These properties are used as a pivot vocabulary in this API. The core of this specification is the definition of API interfaces for retrieving metadata information in synchronous and asynchronous way as well as interfaces for structured return types along with the specification of the behavior of an API implementation. The API has been designed for both client and server side implementations.

Status of This Document

This section describes the status of this document at the time of its publication. Other documents may supersede this document. A list of current W3C publications and the latest revision of this technical report can be found in the W3C technical reports index at http://www.w3.org/TR/.

This is the Candidate Recommendation of the API for Media Resources 1.0 specification.

It has been produced by the Media Annotations Working Group, which is part of the W3C Video on the Web Activity. The Working Group expects to advance this specification to Recommendation Status.

Please send review comments about this Candidate Recommendation to the public mailing list public-media-annotation@w3.org mailing list (public archive). Use "[CR Comment API]" in the subject line of your email. We expect that sufficient feedback to determine its future will have been received by 31 December 2011. This specification will remain a Candidate Recommendation until at least 31 December 2011.

The Media Annotation Working Group will advance this specification to Proposed Recommendation when the following exit criteria have been met:

1. Sufficient reports of implementation experience have been gathered to demonstrate that the API features are implementable and are interpreted in a consistent manner. To do so, the Working Group will insure that all features in the API for Media Resources 1.0 specification have been implemented at least twice in an interoperable way. The following elements are considered features of the API and must be tested by the test suite:

The API is designed for both client- and server side implementations. Depending on whether the API is implemented in a user agent or plugin, or as a web service, different communication patterns are more appropriate. In the client side case, asynchronous access is typically preferred, while synchronous access is more appropriate for a web service. Thus the two version of the interface are not considered distinct features but different modes of access for the different use cases.

2. The implementations have been developed independently.

3. The Working Group has adopted a public test suite and has produced an implementation report for this API for Media Resources 1.0.

The Implementation results are publicly released and are intended solely to be used as proof of Media API 1.0 implementability. It is only a snap shot of the actual implementation behaviors at one moment of time, as these implementations may not be immediately available to the public. The interoperability data is not intended to be used for assessing or grading the performance of any individual implementation. Any feedback on implementation and use of this specification would be very welcome. To the extent possible, please provide a separate email message for each distinct comment.

For convenience, the differences between this CR version and the Second Last Call Working Draft are highlighted in the CR Diff file and listed in the change log in Annexe B.

This W3C Working Draft version of the API for Media Resources 1.0 specification incorporates requests for changes from comments sent during the first and second Last Call Review, as agreed with the commenters (see Disposition of Last Call comments for Ontology for Media Resources 1.0) and changes following implementation experiences from the Working Group.

Publication as a Candidate Recommendation does not imply endorsement by the W3C Membership. This is a draft document and may be updated, replaced or obsoleted by other documents at any time. It is inappropriate to cite this document as other than work in progress.

This document was produced by a group operating under the 5 February 2004 W3C Patent Policy. W3C maintains a public list of any patent disclosures made in connection with the deliverables of the group; that page also includes instructions for disclosing a patent. An individual who has actual knowledge of a patent which the individual believes contains Essential Claim(s) must disclose the information in accordance with section 6 of the W3C Patent Policy.

Table of Contents

1. Introduction

This specification defines an API to access metadata information related to media resources on the Web. The overall purpose is to provide developers with a convenient access to metadata information stored in different metadata formats. The core properties, defined in the Ontology for Media Resources 1.0 specification, will be used as a pivot vocabulary in this API. The description of relations between these core properties and the metadata formats in scope are documented in the Ontology for Media Resources 1.0 specification in order to provide cross-community data integration. This API is described using the interface definition language Web IDL [WEBIDL]. The decision to use Web IDL, which offers bindings for ECMAScript and Java, can be based on the Use Cases and Requirements for Ontology and API for Media Resources 1.0 [MEDIA-ANNOT-REQS].

This API defines/exposes interfaces that enables users/applications to consume metadata in an interoperable manner. Here, interoperability between metadata formats is ensured by the use of the Ontology for Media Resources 1.0 as pivot metadata format. This API offers operations to request particular metadata information represented in a certain metadata format related to media resources on the Web. Further it specifies the actual representation of the core properties and the behaviour of this API.

1.1 Formats in scope

Refers to the formats in scope of Ontology for Media Resources 1.0.

1.2 Formats out of scope

Refers to the Formats out of scope of Ontology for Media Resources 1.0.

1.3 Terminology

In this document the terms "Ontology", "Media Resource", "Property", "Mapping" and "Property value types" are to be interpreted as defined in Section 2 of Ontology for Media Resources 1.0.

2. Conformance

As well as sections marked as non-normative, all authoring guidelines, diagrams, examples, and notes in this specification are non-normative. Everything else in this specification is normative.

The key words must, must not, required, should, should not, recommended, may, and optional in this specification are to be interpreted as described in [RFC2119].

3. Design consideration

Before introducing the two example usage scenarios of this API, two modes of operations must be defined: asynchronous and synchronous mode. For this API the asynchronous mode is considered to be used as default where calls return without waiting for the request to finish its execution: a call-back function is provided to be invoked when the request terminates. In contrast to that, the synchronous mode implicates an immediate answer to every request.

We consider two scenarios, where this API could be implemented:

The two scenarios are shown in Figure 1.

Diagram showing 2 scenarios with different usage of the API.

Figure 1: Two scenarios with different usage of this API.

Note: This specification only defines this API for Media Resources. Other components depicted in Figure 1 (e.g., access/extraction/storage of metadata) are not covered.

Scenario 1: User agent
In this scenario, this API is implemented in a user agent (e.g., browser or browser plugin) and exposed as a JavaScript API (using the WebIDL JavaScript binding). Usually, such an implementation is per default an example for an asynchronous processing. Besides the "API for Media Resources 1.0", the user agent includes components for metadata access (and possibly extraction) and mappings for a supported set of formats, e.g., as defined in the property mapping table of the Ontology for Media Resources 1.0 specification. Further, the metadata sources (the media resource and/or metadata document(s)) must be retrievable, while the access (e.g., establish connection, retrieval) to the metadata sources is handled by the user agent.
Scenario 2: Web service
In the second scenario, this API is encapsulated in a Web Service following the principle of synchronous processing. Such an implementation would be typically used by a non-UI client, such as an agent harvesting metadata. However, this API could be also accessed from a user agent, and used the same way as described in scenario 1 with the help of a JavaScript library for accessing the Web Service. In the implementation of the Web Service, this scenario also allows supporting a media repository (e.g. content provider's archive database, movie store). With the help of such a service the user agent could retrieve metadata sources, which might have a custom metadata format not supported by a user agent. In contrast to an integrated component (see scenario 1), an implementation of this API in a web service could do more complex mappings on the fly than a component integrated in a user agent, and can be more flexible (e.g., supporting additional formats).

In both scenarios, this API serves as a mediator between a client application and the actual metadata sources. Interoperability is ensured by defining i) operations for accessing the metadata information, ii) common object structure and iii) API behaviour (e.g., status codes). Following this, an implementation has to implement this stack of components:

Note that, this API provides access to metadata information stored in different metadata formats. As such, different instances of the same property can exist.

4. API Description

This API defines a number of interfaces using [WEBIDL]. These can be grouped in the following categories:

Next, the different interfaces and exposed operations (in case of the MediaResource interfaces and its implementing interfaces) are discussed. Implementations of this API must support at least one of the versions and must support the other interfaces defined in this document. We have not specified exceptions on the operations or on accessing the attributes. Instead, a status code is returned (in the synchronous API) or can be accessed (in the asynchronous API) in case an error occurs indicating the state of processing (see Section 4.7).

Then, the interfaces for the return types, i.e., MediaAnnotation and its specializations, and MetadataSource are defined.

The IDL fragment in Appendix A of this specification must be interpreted as required for conforming IDL fragments, as described in the “Web IDL” specification. [WEBIDL]

4.1 MediaResource interface

The MediaResource interface is the core of this API and provides operations to access the metadata properties of a specific media resource. Here, a clear separation between asynchronous and synchronous mode of operation has been achieved by defining two implementing interfaces, the AsyncMediaResource and the SyncMediaResource interface. Objects of these interfaces will be created by calling createMediaResource of the MediaResource interface. The actual connection to a specified metadata source will be created with the execution of the getMediaProperty operation of AsyncMediaResource or SyncMediaResource interface.

interface MediaResource {
    short         getSupportedModes ();
    MediaResource createMediaResource (DOMString mediaResource, optional MetadataSource[] metadataSources, optional short mode);
};

4.1.1 Methods

createMediaResource
This operation instantiates an object of either AsyncMediaResource or SyncMediaResource interface. Further, it allows to set the specific media resource and metadata sources to which this API is applied.
Parameter Type Nullable Optional Description
mediaResource DOMString This attribute must set the specific media resource that should be processed by the API.
metadataSources MetadataSource[] This attribute should specify additional metadata sources.
mode short This attribute should specify the desired mode of operation. 1 for asynchronous and 2 for synchronous mode should be used.
No exceptions.
Return type: MediaResource
getSupportedModes
This operation is called to identify the implemented mode. The return codes should be as follows: 1 for asynchronous, 2 for synchronous and 3 for both modes.
No parameters.
No exceptions.
Return type: short

4.1.2 Examples in Javascript

Example for getSupportedModes:

ma = new MediaResource();
var mode = ma.getSupportedModes();

/** Resulting in:
 * { "supportedModes" : 3 }
 */

Example for createMediaResource:

metadataSources = new MetadataSource[2];
metadataSources[0] = new MetadataSource(
                         "http://www.w3.org/2008/WebVideo/Annotations/drafts/metadata_formats/DC_example1.xml","dc");
metadataSources[1] = new MetadataSource(
                         "http://www.w3.org/2008/WebVideo/Annotations/wiki/images/9/93/MAWG-Stockholm-20090626.JPG","exif");

mediaResource = new MediaResource();

if (mediaResource.getSupportedModes() == 1 || mediaResource.getSupportedModes() == 3) {
    aSyncObject = mediaResource.createMediaResource(
                         "http://www.w3.org/2008/WebVideo/Annotations/wiki/images/9/93/MAWG-Stockholm-20090626.JPG",
                         metadataSources, 1);
                             
} else if (mediaResource.getSupportedModes() == 2 || mediaResource.getSupportedModes() == 3)  {
    syncObject = mediaResource.createMediaResource(
                         "http://www.w3.org/2008/WebVideo/Annotations/wiki/images/9/93/MAWG-Stockholm-20090626.JPG",
                         metadataSources, 2);
}

4.2 AsyncMediaResource interface

The AsyncMediaResource interface provides a number of operations that allow accessing the metadata of a media resource. By calling the getMediaProperty operation with the argument "title" we can retrieve the title of the corresponding media resource.

Next, we give the Web IDL description of the AsyncMediaResource interface and describe the different operations that are part of it. The mediaResource argument identifies the media resource, for which the implementation of this API should try to find relevant metadata sources. Optionally, references to metadata sources can be passed using an array of objects, each implementing the MetadataSource interface. This interface holds an URI identifying the metadata source (metadataSource) and the name of the actual metadata format (sourceFormat).

In this section the MediaAnnotations interface is used in the interface definitions. It serves as a container to hold general values about properties enabling an iteration over a set of different properties. Its explanation can be found in Section 4.4

interface AsyncMediaResource : MediaResource {
    void getMediaProperty (DOMString[] propertyNames, PropertyCallback successCallback, ErrorCallback errorCallback, optional DOMString fragment, optional DOMString sourceFormat, optional DOMString language);
    void getOriginalMetadata (DOMString sourceFormat, MetadataCallback successCallback, ErrorCallback errorCallback);
};

4.2.1 Methods

getMediaProperty
This operation allows retrieval of the value of a specific property, several or all properties in an asynchronous manner. The specific property is passed as an argument and a list of objects is returned that hold the values according to the requested property. These objects implement the MediaAnnotation interface, described in Section 4.4. Depending on the requested property, the returned objects implement a different subtypes (inheriting from the MediaAnnotation interface). Requesting "title" gives back an array of objects implementing the Title interface, requesting "creator" results in objects implementing the Creator interface and so on. These interfaces are described in Section 4.5. An example can be found here.
Parameter Type Nullable Optional Description
propertyNames DOMString[] This argument identifies an array containing the properties for which the values need to be retrieved. For an empty array all properties carrying values will be retrieved. Optional arguments allow refining the request.
successCallback PropertyCallback This argument holds a callback object for asynchronous requests to the property. The successCallback object implements the PropertyCallback interface and holds a handleEvent operation that needs to be called once all data for the requested property is gathered. This handleEvent operation needs to be called with a new MediaAnnotation array.
errorCallback ErrorCallback This argument holds a callback object for failure of asynchronous requests to the property. The errorCallback object implements the ErrorCallback interface and holds a handleEvent operation that needs to be called if an attempt fails. This handleEvent operation needs to be called with a new DOMString representing the status code of the error (see Section 4.7 for details).
fragment DOMString This argument contains a URI identifying the specific media fragment for which the metadata is requested. The URI must conform to the URI for Media Fragment [MEDIA-FRAGMENTS] specification. This parameter is optional.
sourceFormat DOMString This argument identifies a specific metadata format. It should use the metadata format identifiers defined in the Ontology for Media Resources 1.0 specification. If a metadata format is defined, only the metadata available in the corresponding metadata format are retrieved. This parameter is optional.
language DOMString This argument allows to identify the language of the metadata. Values for the metadata will only be returned if it is available in the specified language. Recommended best practice is to use BCP 47 [BCP47]. This parameter is optional.
No exceptions.
Return type: void
getOriginalMetadata
This operation allows retrieval of the original metadata according to the specified source format in an asynchronous manner. An example can be found here.
Parameter Type Nullable Optional Description
sourceFormat DOMString This argument identifies a specific metadata format. It should use the metadata format identifiers defined in the Ontology for Media Resources 1.0 specification. If a metadata format is defined, only the metadata available in the corresponding metadata format are retrieved.
successCallback MetadataCallback This argument holds a callback object for asynchronous requests for the original metadata. The successCallback object implements the MetadataCallback interface and holds a handleEvent operation that needs to be called once all properties having values are listed. This handleEvent operation needs to be called with a new DOMString array holding the original metadata.
errorCallback ErrorCallback This argument holds a callback object for failure of asynchronous requests for the original metadata. The errorCallback object implements the ErrorCallback interface and holds a handleEvent operation that needs to be called if an attempt fails. This handleEvent operation needs to be called with a new DOMString representing the status code of the error (see Section 4.7 for details).
No exceptions.
Return type: void

4.2.2 Callback interfaces

4.2.2.1 PropertyCallback interface

The PropertyCallback interface holds a handleEvent operation that needs to be called once all data for the requested property has been gathered.

interface PropertyCallback {
    void handleEvent (MediaAnnotation[] mediaAnnotations);
};
4.2.2.1.1 Methods
handleEvent
This operation is called when all data is gathered corresponding to a request for values of one or more properties.
Parameter Type Nullable Optional Description
mediaAnnotations MediaAnnotation[] This argument holds a list of objects with values according to the requested property. These objects implement the MediaAnnotation interface, described in Section 4.4. Depending on the requested property, the returned objects implement a different subtypes (inheriting from the MediaAnnotation interface).
No exceptions.
Return type: void
4.2.2.2 MetadataCallback interface

The MetadataCallback interface holds a handleEvent operation that needs to be called once the requested metadata has been gathered.

interface MetadataCallback {
    void handleEvent (DOMString[] metadata);
};
4.2.2.2.1 Methods
handleEvent
This operation is called when all data is gathered corresponding to a request for the original metadata.
Parameter Type Nullable Optional Description
metadata DOMString[] This argument holds a list of DOMStrings representing the original metadata. Note that, multiple metadata instances can exist (e.g., one Dublin core and one MPEG-7 document).
No exceptions.
Return type: void

4.2.3 Examples in Javascript

Example for asynchronous getMediaProperty:

aSyncMediaResource = mediaResource.createMediaResource("http://www.imdb.com/title/tt0133152/", new Array(), 1);
aSyncMediaResource.getMediaProperty(["title"], successCallback, errorCallback, "", "", "");
                                
function successCallback(MediaAnnotation[] mediaAnnotations) {
    ...
}

/** Resulting in:
 * [ { "Title" : {
 *         "propertyName" : "title",
 *         "value" : "Planet of the apes",
 *         "language" : en-us",
 *         ...
 *         "statusCode" : 200
 *         }
 * },
 * { "Title" : {
 *         "propertyName" : "title",
 *         "value" : "Monkey Planet",
 *         "language" : en-us",
 *         ...,
 *         "statusCode" : 200
 *         }
 * },
 * { ...
 * } ]
 */
                
function errorCallback(DOMString error) {
    ...
}

/** Resulting in:
 * { error: { "statusCode" : 415 } }
 */

Example for asynchronous getOriginalMetadata :

aSyncMediaResource = mediaResource.createMediaResource(
                         "http://www.w3.org/2008/WebVideo/Annotations/wiki/images/9/93/MAWG-Stockholm-20090626.JPG",
                          new Array(), 1);
aSyncMediaResource.getOriginalMetadata("dc", successCallback, errorCallback);

function successCallback(DOMString[] metadata) {
    ...
}

/** Resulting in:
 * [ { "statusCode" : 200
 * },
 * {"originalMetadata" : "<metadata xmlns='http://example.org/myapp/'
 *                                        xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance'
 *                                        xsi:schemaLocation='http://example.org/myapp/ http://example.org/myapp/schema.xsd'
 *                                        xmlns:dc='http://purl.org/dc/elements/1.1/'>
 *                                          <dc:title>DC title</dc:title>
 *                                  </metadata>"
 * } ]
 */

                                                
function errorCallback(DOMString error) {
   ...
}

/** Resulting in:
 * { error: { "statusCode" : 415 } }
 */

4.3 SyncMediaResource interface

The SyncMediaResource interface provides a number of operations to access the metadata of a media resource. Next, we give the Web IDL description of the SyncMediaResource interface for synchronous requests and describe the different operations that are part of it. The MediaResource defines a constructor that can be called to construct the object based on an identifier of the media resource and optionally some metadata sources. The mediaResource argument identifies the media resource, for which the implementation of this API should try to find relevant metadata sources. Optionally, references to metadata sources can be passed using an array of objects, each implementing the MetadataSource interface. This interface holds two attributes, namely an URI identifying the metadata source (metadataSource) and the name of the actual metadata format (sourceFormat). An example, how to create this object can be found here.

interface SyncMediaResource : MediaResource {
    MediaAnnotation[] getMediaProperty (DOMString[] propertyNames, optional DOMString fragment, optional DOMString sourceFormat, optional DOMString language);
    DOMString[]       getOriginalMetadata (DOMString sourceFormat);
};

4.3.1 Methods

getMediaProperty
This operation allows retrieval of the metadata of a specific property, several or all properties in a synchronous manner. The passed array holds the requested properties and a array of objects is returned. If the array is empty, every property holding values will be requested and returned. The returned objects implement the MediaAnnotation interface (see Section 4.3). Depending on the requested property, the returned objects implement a different subtypes (inheriting from the MediaAnnotation interface). Requesting "title" gives back an array of objects implementing the Title interface, requesting "creator" results in objects implementing the Creator interface and so on. These subtypes are described in Section 4.4. The operation returns a MediaAnnotation array holding the requested properties. If an error occurs during retrieval, a MediaAnnotation object with the corresponding status code (e.g., 400, 404 or 415) will be generated and inserted at the first position of the array. An example can be found here.

In this section the MediaAnnotations interface is used in the interface definitions. It serves as a container to hold general values about properties enabling an iteration over a set of different properties. Its explanation can be found in Section 4.4

Parameter Type Nullable Optional Description
propertyNames DOMString[] This argument holds the requested properties as an array. If the array is empty, each property holding values will be returned.
fragment DOMString This argument contains a URI identifying the specific media fragment for which the metadata is requested. The URI must conform to the URI for Media Fragment[MEDIA-FRAGMENTS] specification. This parameter is optional.
sourceFormat DOMString This argument identifies a specific metadata format. It should use the metadata format identifiers defined in the Ontology for Media Resources 1.0 specification. If a metadata format is defined, only the metadata available in the corresponding metadata format is retrieved. This parameter is optional.
language DOMString This argument allows to identify the language of the metadata. Values for the metadata will only be returned if it is available in the specified language. Recommended best practice is to use BCP 47 [BCP47]. This parameter is optional.
No exceptions.
Return type: MediaAnnotation[]
getOriginalMetadata
This operation allows retrieval of the original metadata according to the specified source format in a synchronous manner. The operation returns a DOMString array holding the status code of the request at the first and the original metadata at the second position. An example can be found here.
Parameter Type Nullable Optional Description
sourceFormat DOMString This argument identifies a specific metadata format. It should use the metadata format identifiers defined in the Ontology for Media Resources 1.0 specification. If a metadata format is defined, only the metadata available in the corresponding metadata format is retrieved.
No exceptions.
Return type: DOMString[]

4.3.2 Examples in Javascript

The examples in this section use getMediaProperty() to get an object implementing the MediaAnnotation interface. The noErrorStatus function ensures that no error is present and the requested properties carry values.

We give some JavaScript examples on how to use the synchronous MediaResource interface and it's operations.

Example for synchronous getMediaProperty:

syncMediaResource = mediaResource.createMediaResource("http://www.imdb.com/title/tt0133152/",
                          new Array(), 2);
title = syncMediaResource.getMediaProperty(["title"], "", "", "");

if (noErrorStatus(title[0].statusCode) == true) {
   ...
}                                                

/** Resulting in:
 * [ { "Title" : {
 *         "propertyName" : "title",
 *         "value" : "Planet of the apes",
 *         "language" : en-us",
 *         ...,
 *         "statusCode" : 200
 *         }
 * },
 * { "Title" : {
 *         "propertyName" : "title",
 *         "value" : "Planet der Affen",
 *         "language" : "de-de",
 *         ...,
 *         "statusCode" : 200
 *         }
 * },
 * { ...
 * } ]
 */

Example for synchronous getOriginalMetadata:

syncMediaResource = mediaResource.createMediaResource("http://www.w3.org/2008/WebVideo/Annotations/wiki/images/9/93/MAWG-Stockholm-20090626.JPG",
                         new Array(), 2);
dcMetadata = syncMediaResource.getOriginalMetadata("DC");

if (noErrorStatus(dcMetadata[0].statusCode) == true) {
    ...
}

/** Resulting in:
 * [ { "statusCode" : 200
 * },
 * {"originalMetadata" : "<metadata xmlns='http://example.org/myapp/'
 *                                        xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance'
 *                                        xsi:schemaLocation='http://example.org/myapp/ http://example.org/myapp/schema.xsd'
 *                                        xmlns:dc='http://purl.org/dc/elements/1.1/'>
 *                                          <dc:title>DC title</dc:title>
 *                                  </metadata>"
 * } ]
 */

4.4 MediaAnnotation interface

MediaAnnotation interface is used as the return type of MediaResource.getMediaProperty operation. It is a container to hold general values about properties enabling an iteration over a set of different properties. Depending on the requested property, this interface will be enlarged by more specific attributes.

As several properties are complex types, specific derived types of MediaAnnotation have been defined, added these properties with the appropriate types. However, MediaAnnotation can be used as a generic return type to access a printable string representation of the property (in the value attribute). It also includes a status code. In case of general errors, the first element of the returned MediaAnnotation array contains the global error code, otherwise the status can be given for each of the returned properties.

The following design considerations have been used for specifying the derived types for each of the properties:

interface MediaAnnotation {
    attribute DOMString propertyName;
    attribute DOMString value;
    attribute DOMString language;
    attribute DOMString sourceFormat;
    attribute DOMString fragmentIdentifier;
    attribute DOMString mappingType;
    attribute short     statusCode;
};

4.4.1 Attributes

fragmentIdentifier of type DOMString
This attribute should be an URI determining the fragment for which the metadata is relevant.
No exceptions.
language of type DOMString
This attribute should hold the language of the metadata. The attribute is empty if language is not applicable for a specific property. Recommended best practice is to use BCP 47 [BCP47].
No exceptions.
mappingType of type DOMString
This attribute specifies the kind of mapping as discussed in the semantic level mappings. The value of this attribute should be one of the mapping characteristics.
No exceptions.
propertyName of type DOMString
The name of the property must be specified and should correspond to the property names defined in the Ontology for Media Resources 1.0 specification.
No exceptions.
sourceFormat of type DOMString
This attribute allows to specify the metadata source from which the metadata was retrieved. It should use the metadata format identifiers defined in theOntology for Media Resources 1.0 specification.
No exceptions.
statusCode of type short
This attribute must specify the status code for the associated property (e.g., 264 indicating a structured return value).
No exceptions.
value of type DOMString
This attribute must be filled with an printable string representation.
No exceptions.

4.4.2 Example in JavaScript

The noErrorStatus function ensures that no error is present and the requested properties carry values. The MediaAnnotation interface will be never instantiated - only the implementing subtypes will be created. These must be filled at least with the parameters specified in the MediaAnnotation interface and may be filled with the specific attributes.

mediaAnnotation = image.getMediaProperty(["title"], "", "", "");

if (noErrorStatus(mediaAnnotation[0].statusCode) == true) {                    
   ...
}

/** Resulting in:
 * [ { "Title" : {
 *         "propertyName" : "title",
 *         "value" : "Gone with the Wind",
 *         "language" : "en-us",
 *         "sourceFormat" : "mpeg7",
 *         "fragmentIdentifier" : "http://www.example.com/video.ogv#t=10,20",
 *         "mappingType" : "Exact match",
 *         "statusCode" : 200
 *         } 
 * } ]

4.5 Properties

This section describes the different properties that can be requested through the MediaResource.getMediaProperty() operation. When invoking this operation, objects implementing the MediaAnnotation interface are returned that represent the specified property. All properties are represented with an interface inherited from the MediaAnnotation interface (following the design guidelines described above).

Several of the following return type interfaces can hold the value of the property as both URI (i.e., a pointer to a controlled vocabulary) or as free text. The URI is preferred, and the respective attribute of the return value shall be filled whenever possible (i.e., when the information is included in or can be constructed from the source metadata).

In the following, for each property, a (synchronous) JavaScript example illustrates the usage of the property specific attributes. In any case, the genereal attributes of the MediaAnnotation interface could be also requested.

4.5.1 Identification Properties

4.5.1.1 Identifier

When the MediaResource.getMediaProperty operation is invoked with "identifier" as a value of the propertyName parameter, an object implementing the Identifier interface is returned representing the identifier property (defined in the Ontology for Media Resources 1.0 specification).

interface Identifier : MediaAnnotation {
    attribute DOMString identifierLink;
};
4.5.1.1.1 Attributes
This attribute holds a URI identifying the media resource.
No exceptions.
4.5.1.1.2 Example in JavaScript
id = image.getMediaProperty(["identifier"]);
                                     
/** Resulting in:
 * [ { "Identifier" : {
 *         "propertyName" : "identifier",
 *         "identifierLink" : "urn:uuid:36a87260-1102-11df-8a39-0800200c9a66",                    
 *         "statusCode" : 200
 *         } 
 * } ]
 */
4.5.1.2 Title

When the MediaResource.getMediaProperty operation is invoked with "title" as a value of the propertyName parameter, an object implementing the Title interface is returned representing the title property (defined in the Ontology for Media Resources 1.0 specification).

interface Title : MediaAnnotation {
    attribute DOMString titleLabel;
    attribute DOMString typeLink;
    attribute DOMString typeLabel;
};
4.5.1.2.1 Attributes
titleLabel of type DOMString
This attribute hold the title as a plain string.
No exceptions.
typeLabel of type DOMString
This attribute holds the type of the title as a plain string.
No exceptions.
This attribute holds the type of the title as a URI.
No exceptions.
4.5.1.2.2 Example in JavaScript
title = song.getMediaProperty(["title"]);
                    
/** Resulting in:
 * [ { "Title" : {
 *         "propertyName" : "title",
 *         "titleLabel" : "Artificial Horizon" ,
 *         "typeLink" : "http://www.ebu.ch/metadata/cs/ebu_ObjectTypeCodeCS.xml#21",
 *         "typeLabel" : "Album title",
 *         "statusCode" : 200
 *         }
 * } ]
 */
4.5.1.3 Language

When the MediaResource.getMediaProperty operation is invoked with "language" as a value of the propertyName parameter, an object implementing the Language interface is returned representing the language property (defined in the Ontology for Media Resources 1.0 specification).

interface Language : MediaAnnotation {
    attribute DOMString languageLink;
    attribute DOMString languageLabel;
};
4.5.1.3.1 Attributes
languageLabel of type DOMString
This attribute represents the language of the media resource as a plain string, which can be filtered on in the getMediaProperty operation. Recommended best practice is to use BCP 47 [BCP47].
No exceptions.
This attribute represents the language of the media resource as a URI.
No exceptions.
4.5.1.3.2 Example in JavaScript
language = video.getMediaProperty(["language"]);
        
/** Resulting in:
 * [ { "Language" : {
 *         "propertyName" : "language",
 *         "languageLabel" : "en-us",                    
 *         "statusCode" : 200
 *         }
 * } ]
 */
4.5.1.4 Locator

When the MediaResource.getMediaProperty operation is invoked with "locator" as a value of the propertyName parameter, an object implementing the Locator interface is returned representing the locator property (defined in the Ontology for Media Resources 1.0 specification).

interface Locator : MediaAnnotation {
    attribute DOMString locatorLink;
};
4.5.1.4.1 Attributes
This attribute specifies the location of the media resource by a URI.
No exceptions.
4.5.1.4.2 Example in JavaScript
locator = image.getMediaProperty(["locator"]);

/** Resulting in:
 * [ { "Locator" : {
 *         "propertyName" : "locator",
 *         "locatorLink" : "http://www.w3.org/2008/WebVideo/Annotations/wiki/images/9/93/MAWG-Stockholm-20090626.JPG",                    
 *         "statusCode" : 200
 *         } 
 * } ]
 */

4.5.2 Creation Properties

4.5.2.1 Contributor

When the MediaResource.getMediaProperty operation is invoked with "contributor" as a value of the propertyName parameter, an object implementing the Contributor interface is returned representing the contributor property (defined in the Ontology for Media Resources 1.0 specification).

interface Contributor : MediaAnnotation {
    attribute DOMString contributorLink;
    attribute DOMString contributorLabel;
    attribute DOMString roleLink;
    attribute DOMString roleLabel;
};
4.5.2.1.1 Attributes
contributorLabel of type DOMString
This attribute represents the contributor (i.e., the agent making the contribution) as a plain string
No exceptions.
This attribute represents the contributor (i.e., the agent making the contribution) as a URI.
No exceptions.
roleLabel of type DOMString
This attribute represents the role of the contributor as a plain string.
No exceptions.
This attribute represents the role of the contributor as URI.
No exceptions.
4.5.2.1.2 Example in JavaScript
contributor = video.getMediaProperty(["contributor"]);

/** Resulting in:
 * [ { "Contributor" : {
 *         "propertyName" : "contributor",
 *         "contributorLink" : "http://en.wikipedia.org/wiki/Tim_Burton",
 *         "contributorLabel" : "Tim Burton",
 *         "roleLink" : "http://www.imdb.com/name/nm0000318/",
 *         "roleLabel" : "director",                    
 *         "statusCode" : 200
 *         } 
 * } ]
 */
4.5.2.2 Creator

When the MediaResource.getMediaProperty operation is invoked with "creator" as a value of the propertyName parameter, an object implementing the Creator interface is returned representing the creator property (defined in the Ontology for Media Resources 1.0 specification).

interface Creator : MediaAnnotation {
    attribute DOMString creatorLink;
    attribute DOMString creatorLabel;
    attribute DOMString roleLink;
    attribute DOMString roleLabel;
};
4.5.2.2.1 Attributes
creatorLabel of type DOMString
This attribute represents the creator (i.e., the agent participating in the creation of the media resource) as a plain string.
No exceptions.
This attribute represents the creator (i.e., the agent participating in the creation of the media resource) as a URI.
No exceptions.
roleLabel of type DOMString
This attribute represents the role of the creator as a plain string.
No exceptions.
This attribute represents the role of the creator as URI.
No exceptions.
4.5.2.2.2 Example in JavaScript
creator = video.getMediaProperty(["creator"]);

/** Resulting in:
 * [ { "Creator" : {
 *         "propertyName" : "creator",
 *         "creatorLink" : "http://dbpedia.org/resource/William_Shakespeare",
 *         "creatorLabel" : "William Shakespeare",
 *         "roleLink" : "http://www.ebu.ch/metadata/cs/ebu_RoleCodeCS.xml#22.5",
 *         "roleLabel" : "playwright",                    
 *         "statusCode" : 200
 *         }
 * } ]
 */
4.5.2.3 MADate

When the MediaResource.getMediaProperty operation is invoked with "date" as a value of the propertyName parameter, an object implementing the Date interface is returned representing the date property (defined in the Ontology for Media Resources 1.0 specification). This property has been renamed from "Date" into "MADate" since the appearance of naming conflicts is possible in web applications.

interface MADate : MediaAnnotation {
    attribute DOMString date;
    attribute DOMString typeLink;
    attribute DOMString typeLabel;
};
4.5.2.3.1 Attributes
date of type DOMString
This attribute represents date related to the media resource. A date value must be represented using one of the specific date/time data types of XML Schema, depending on the available precision: gYear gYearMonth, date, dateTime, or dateTimeStamp.
No exceptions.
typeLabel of type DOMString
This attribute defines the category of date (e.g. creation date, broadcast date, release date, date recorded and date edited) as a plain string.
No exceptions.
This attribute defines the category of date (e.g. creation date, broadcast date, release date, date recorded and date edited) as a URI.
No exceptions.
4.5.2.3.2 Example in JavaScript
maDate = video.getMediaProperty(["date"]);

/** Resulting in:
 * [ { "MADate" : {
 *         "propertyName" : "date",
 *         "date": "2009-06-26T15:30:00",
 *         "typeLink" : "urn:smpte:ul:06.0E.2B.34.01.01.01.02.07.02.01.10.02.03.00.00",
 *         "typeLabel" : "modification date",
 *         "statusCode" : 200
 *         }
 * } ]
 */
4.5.2.4 Location

When the MediaResource.getMediaProperty operation is invoked with "location" as a value of the propertyName parameter, an object implementing the Location interface is returned representing the location property (defined in the Ontology for Media Resources 1.0 specification).

interface Location : MediaAnnotation {
    attribute DOMString locationLink;
    attribute DOMString locationLabel;
    attribute double    longitude;
    attribute double    latitude;
    attribute double    altitude;
    attribute DOMString coordinateSystemLabel;
    attribute DOMString coordinateSystemLink;
};
4.5.2.4.1 Attributes
altitude of type double
This attribute holds the altitude of the location, w.r.t. the coordinate system specified by the coordiateSystem attribute (default is WGS84).
No exceptions.
coordinateSystemLabel of type DOMString
This attribute identified the coordinate system used by its name.
No exceptions.
This attribute identified the coordinate system used by a URI.
No exceptions.
latitude of type double
This attribute holds the latitude of the location, w.r.t. the coordinate system specified by the coordiateSystem attribute (default is WGS84).
No exceptions.
locationLabel of type DOMString
This attribute identifies the location by its name as a plain string.
No exceptions.
This attribute identifies the location as a URI.
No exceptions.
longitude of type double
This attribute holds the longitude of the location, w.r.t. the coordinate system specified by the coordiateSystem attribute (default is WGS84).
No exceptions.
4.5.2.4.2 Example in JavaScript
location = video.getMediaProperty(["location"]);

/** Resulting in:
 * [ { "Location" : {
 *         "propertyName" : "location",
 *         "locationLink" : "http://en.wikipedia.org/wiki/San_Jose,_California",
 *         "locationLabel" : "San Jose",
 *         "longitude" : 37.33986481118008,
 *         "latitude" : -121.88507080078125,
 *         "altitude" : 0,
 *         "coordinateSystemLabel" : "WGS84",
 *         "coordinateSystemLink" : "http://www.w3.org/2003/01/geo/wgs84_pos#Point",
 *         "statusCode" : 200
 *         }
 * } ]
 */

4.5.3 Content Properties

4.5.3.1 Description

When the MediaResource.getMediaProperty operation is invoked with "description" as a value of the propertyName parameter, an object implementing the Description interface is returned representing the description property (defined in the Ontology for Media Resources 1.0 specification).

interface Description : MediaAnnotation {
    attribute DOMString descriptionLabel;
};
4.5.3.1.1 Attributes
descriptionLabel of type DOMString
This attribute contains a description of the content of the media resource.
No exceptions.
4.5.3.1.2 Example in Javascript
description = image.getMediaProperty(["description"]);

/** Resulting in:
 * [ { "Description" : {
 *         "propertyName" : "description",
 *         "descriptionLabel" : "Group picture of the W3C MAWG at the F2F meeting in Stockholm.",
 *         "statusCode" : 200
 *         }
 * } ]
 */
4.5.3.2 Keyword

When the MediaResource.getMediaProperty operation is invoked with "keyword" as a value of the propertyName parameter, an object implementing the Keyword interface is returned representing the keyword property (defined in the Ontology for Media Resources 1.0 specification).

interface Keyword : MediaAnnotation {
    attribute DOMString keywordLabel;
    attribute DOMString keywordLink;
};
4.5.3.2.1 Attributes
keywordLabel of type DOMString
This attribute contains a keyword describing the content as a plain string.
No exceptions.
This attribute contains a URI representing a keyword describing the content.
No exceptions.
4.5.3.2.2 Example in Javascript
keyword = image.getMediaProperty(["keyword"]);

/** Resulting in:
 * [ { "Keyword" : {
 *         "propertyName" : "keyword",
 *         "keywordLabel" : "meeting with people from outside the organisation",
 *         "keywordLink" : "http://sw.opencyc.org/2008/06/10/concept/en/MeetingWithOrganizationalOutsiders",                    
 *         "statusCode" : 200
 *         }
 * }, 
 * { "Keyword" : {
 *         "propertyName" : "keyword",
 *         "keywordLabel" : "standardisation",
 *         "keywordLink" : "http://purl.org/vocabularies/princeton/wn30/synset-standardization-noun-1",                    
 *         "statusCode" : 200
 *         } 
 * } ]
 */
4.5.3.3 Genre

When the MediaResource.getMediaProperty operation is invoked with "genre" as a value of the propertyName parameter, an object implementing the Genre interface is returned representing the genre property (defined in the Ontology for Media Resources 1.0 specification).

interface Genre : MediaAnnotation {
    attribute DOMString genreLabel;
    attribute DOMString genreLink;
};
4.5.3.3.1 Attributes
genreLabel of type DOMString
This attribute represents the genre of the media resource as a plain string.
No exceptions.
This attribute represents the genre of the media resource as a URI.
No exceptions.
4.5.3.3.2 Example in Javascript
genre = image.getMediaProperty(["genre"]);

/** Resulting in:
 * [ { "Genre" : {
 *         "propertyName" : "genre",
 *         "genreLabel" : "Sports",
 *         "genreLink" : "http://www.ebu.ch/metadata/cs/ebu_ContentGenreCS.xml#3.1.1.9"                    
 *         "statusCode" : 200
 *         } 
 * } ]
 */
4.5.3.4 Rating

When the MediaResource.getMediaProperty operation is invoked with "rating" as a value of the propertyName parameter, an object implementing the Rating interface is returned representing the rating property (defined in the Ontology for Media Resources 1.0 specification).

interface Rating : MediaAnnotation {
    attribute double    ratingValue;
    attribute DOMString ratingSystemLabel;
    attribute DOMString ratingSystemLink;
    attribute double    minimum;
    attribute double    maximum;
};
4.5.3.4.1 Attributes
maximum of type double
This attribute specifies the maximum rating value in the rating system.
No exceptions.
minimum of type double
This attribute specifies the minimum rating value in the rating system.
No exceptions.
ratingSystemLabel of type DOMString
This attribute identifies the rating system by a plain string.
No exceptions.
This attribute identifies the rating system as a URI.
No exceptions.
ratingValue of type double
This attribute contains the value of the rating.
No exceptions.
4.5.3.4.2 Example in Javascript
rating = image.getMediaProperty(["rating"]);

/** Resulting in:
 * [ { "Rating" : {
 *         "propertyName" : "rating",
 *         "ratingValue" : 10.0,
 *         "ratingSystemLabel" : "John Doe",
 *         "ratingSystemLink" : "http://individuals.example.com/JohnDoe",
 *         "minimum" : 0,
 *         "maximum" : 10.0,                    
 *         "statusCode" : 200
 *         } 
 * } ]
 */

4.5.4 Relational Properties

4.5.4.1 Relation

When the MediaResource.getMediaProperty operation is invoked with "relation" as a value of the propertyName parameter, an object implementing the Relation interface is returned representing the relation property (defined in the Ontology for Media Resources 1.0 specification).

interface Relation : MediaAnnotation {
    attribute DOMString targetLink;
    attribute DOMString targetLabel;
    attribute DOMString typeLink;
    attribute DOMString typeLabel;
};
4.5.4.1.1 Attributes
targetLabel of type DOMString
This attribute identifies the related resource by a plain string.
No exceptions.
This attribute identifies the related resource by a URI.
No exceptions.
typeLabel of type DOMString
This attribute specifies the type of relationship by a plain string.
No exceptions.
This attribute specifies the type of relationship by a URI.
No exceptions.
4.5.4.1.2 Example in Javascript
relation = image.getMediaProperty(["relation"]);

/** Resulting in:
 * [ { "Relation" : {
 *         "propertyName" : "relation",
 *         "targetLink" : "http://www.w3.org/2008/WebVideo/Annotations/wiki/Image:MAWG-Stockholm-20090626_thumb.JPG",
 *         "targetLabel" : "Group picture of MAWG in Stockholm",
 *         "typeLink" : "http://www.ebu.ch/metadata/cs/ebu_HowRelatedCS.xml#19",
 *         "typeLabel" : "thumbnail",                    
 *         "statusCode" : 200
 *         }
 * } ]
 */
4.5.4.2 Collection

When the MediaResource.getMediaProperty operation is invoked with "collection" as a value of the propertyName parameter, an object implementing the Collection interface is returned representing the collection property (defined in the Ontology for Media Resources 1.0 specification).

interface Collection : MediaAnnotation {
    attribute DOMString collectionLink;
    attribute DOMString collectionLabel;
};
4.5.4.2.1 Attributes
collectionLabel of type DOMString
This attribute holds the name of the collection from which the media resource originates as a plain string.
No exceptions.
This attribute holds the name of the collection from which the media resource originates as URI.
No exceptions.
4.5.4.2.2 Example in Javascript
collection = image.getMediaProperty(["collection"]);

/** Resulting in:
 * [ { "Collection" : {
 *         "propertyName" : "collection",
 *         "collectionLink" : "http://individuals.example.com/JohnDoe/myWorkPictures/",
 *         "collectionLabel" : "My Work Pictures",                    
 *         "statusCode" : 200
 *         } 
 * } ]
 */

4.5.5 Rights Properties

4.5.5.2 Policy

When the MediaResource.getMediaProperty operation is invoked with "policy" as a value of the propertyName parameter, an object implementing the Policy interface is returned representing the policy property (defined in the Ontology for Media Resources 1.0 specification).

interface Policy : MediaAnnotation {
    attribute DOMString statementLink;
    attribute DOMString statementLabel;
    attribute DOMString typeLink;
    attribute DOMString typeLabel;
};
4.5.5.2.1 Attributes
statementLabel of type DOMString
This attribute contains a plain string of the policy statement.
No exceptions.
This attribute contains a URI of the policy statement.
No exceptions.
typeLabel of type DOMString
This attribute identifies the type of the policy as a URI as a plain string.
No exceptions.
This attribute identifies the type of the policy as a URI.
No exceptions.
4.5.5.2.2 Example in Javascript
policy = image.getMediaProperty(["policy"]);

/** Resulting in:
 * [ { "Policy" : {
 *         "propertyName" : "policy",
 *         "statementLink" : "http://creativecommons.org/licenses/by/2.5/",
 *         "statementLabel" : "Attribution 2.5 Generic (CC BY 2.5)",
 *         "typeLabel" : "license",                    
 *         "statusCode" : 200
 *         }
 * } ]
 */

4.5.6 Distribution Properties

4.5.6.1 Publisher

When the MediaResource.getMediaProperty operation is invoked with "publisher" as a value of the propertyName parameter, an object implementing the Publisher interface is returned representing the publisher property (defined in the Ontology for Media Resources 1.0 specification).

interface Publisher : MediaAnnotation {
    attribute DOMString publisherLink;
    attribute DOMString publisherLabel;
};
4.5.6.1.1 Attributes
publisherLabel of type DOMString
This attribute represents the publisher as a plain string.
No exceptions.
This attribute represents the publisher as a URI.
No exceptions.
4.5.6.1.2 Example in Javascript
publisher = image.getMediaProperty(["publisher"]);

/** Resulting in:
 * [ { "Publisher" : {
 *         "propertyName" : "publisher",
 *         "publisherLabel" : "ACME",
 *         "publisherLink" : "http://company.example.com/ACME",                    
 *         "statusCode" : 200
 *         } 
 * } ]
 */
4.5.6.2 TargetAudience

When the MediaResource.getMediaProperty operation is invoked with "targetAudience" as a value of the propertyName parameter, an object implementing the TargetAudience interface is returned representing the targetAudience property (defined in the Ontology for Media Resources 1.0 specification).

interface TargetAudience : MediaAnnotation {
    attribute DOMString audienceLink;
    attribute DOMString audienceLabel;
    attribute DOMString classificationSystemLink;
    attribute DOMString classificationSystemLabel;
};
4.5.6.2.1 Attributes
audienceLabel of type DOMString
This attribute identifies the target audience by a plain string.
No exceptions.
This attribute identifies the target audience by a URI.
No exceptions.
classificationSystemLabel of type DOMString
This attribute specifies the classification system by a plain string.
No exceptions.
This attribute specifies the classification system by a URI.
No exceptions.
4.5.6.2.2 Example in Javascript
targetAudience = image.getMediaProperty(["targetAudience"]);

/** Resulting in:
 * [ { "TargetAudience" : {
 *         "propertyName" : "targetAudience",
 *         "audienceLink" : "http://www.mpaa.org/ratings/what-each-rating-means#NC-17",
 *         "audienceLabel" : "No One 17 and Under Admitted",
 *         "classificationSystemLink" : "http://www.mpaa.org/ratings",
 *         "classificationSystemLabel" : "MPAA",                    
 *         "statusCode" : 200
 *         }
 * } ]
 */

4.5.7 Fragments Properties

4.5.7.1 Fragment

When the MediaResource.getMediaProperty operation is invoked with "fragment" as a value of the propertyName parameter, an object implementing the Fragment interface is returned representing the fragment property (defined in the Ontology for Media Resources 1.0 specification).

interface Fragment : MediaAnnotation {
    attribute DOMString identifier;
    attribute DOMString roleLink;
    attribute DOMString roleLabel;
};
4.5.7.1.1 Attributes
identifier of type DOMString
This attribute identifies the fragment as Media Fragment URI (temporal, spatial or track).
No exceptions.
roleLabel of type DOMString
This attribute identifies the role of the fragment as a plain string, which can be filtered on in the getMediaProperty operation.
No exceptions.
This attribute identifies the role of the fragment as a URI, which can be filtered on in the getMediaProperty operation.
No exceptions.
4.5.7.1.2 Example in Javascript
fragment = movie.getMediaProperty(["fragment"]);

/** Resulting in:
 * [ { "Fragment" : {
 *         "propertyName" : "fragment",
 *         "identifier" : "http://www.example.com/video.ogv#t=10,20",
 *         "roleLabel" : "chapter",                    
 *         "statusCode" : 200
 *         }
 * } ]
 */
4.5.7.2 NamedFragment

When the MediaResource.getMediaProperty operation is invoked with "namedFragment" as a value of the propertyName parameter, an object implementing the NamedFragment interface is returned representing the namedFragment property (defined in the Ontology for Media Resources 1.0 specification).

interface NamedFragment : MediaAnnotation {
    attribute DOMString identifier;
    attribute DOMString label;
};
4.5.7.2.1 Attributes
identifier of type DOMString
This attribute identifies a named fragment by a Media Fragment URI.
No exceptions.
label of type DOMString
This attribute contains a plain text label of a named media fragment, which can be used to contruct a Media Fragment URI fro a named fragment.
No exceptions.
4.5.7.2.2 Example in Javascript
namedFragment = movie.getMediaProperty(["namedFragment"]);

/** Resulting in:
 * [ { "NamedFragment" : {
 *         "propertyName" : "namedFragment",
 *         "identifier" : "http://www.example.com/video.ogv#t=30,35",
 *         "label" : "kissScene",
 *         "statusCode" : 200
 *         } 
 * } ]
 */

4.5.8 Technical Properties

4.5.8.1 FrameSize

When the MediaResource.getMediaProperty operation is invoked with "frameSize" as a value of the propertyName parameter, an object implementing the FrameSize interface is returned representing the frameSize property (defined in the Ontology for Media Resources 1.0 specification).

interface FrameSize : MediaAnnotation {
    attribute double    width;
    attribute double    height;
    attribute DOMString unit;
};
4.5.8.1.1 Attributes
height of type double
This attribute represents the height of the frame.
No exceptions.
unit of type DOMString
This attribute represents the unit of the frame width/height. The default value is pixels.
No exceptions.
width of type double
This attribute represents the width of the frame.
No exceptions.
4.5.8.1.2 Example in Javascript
frameSize = image.getMediaProperty(["frameSize"]);

/** Resulting in:
 * [ { "FrameSize" : {
 *         "propertyName" : "framesize",
 *         "width" : 3072,
 *         "height" : 2304,
 *         "unit" : "pixels",                    
 *         "statusCode" : 200
 *         } 
 * } ]
 */
4.5.8.2 Compression

When the MediaResource.getMediaProperty operation is invoked with "compression" as a value of the propertyName parameter, an object implementing the Compression interface is returned representing the compression property (defined in the Ontology for Media Resources 1.0 specification).

interface FrameSize : MediaAnnotation {
    attribute DOMString compressionLink;
    attribute DOMString compressionLabel;
};
4.5.8.2.1 Attributes
compressionLabel of type DOMString
This attribute specifies the compression type of the media resource as a plain string.
No exceptions.
This attribute specifies the compression type of the media resource by a URI.
No exceptions.
4.5.8.2.2 Example in Javascript
compression = video.getMediaProperty(["compression"]);

/** Resulting in:
 * [ { "Compression" : {
 *         "propertyName" : "compression",
 *         "compressionLabel" : "H.264/AVC",
 *         "compressionLink" : "urn:example-org:codingnames2010#ITU-H264",                    
 *         "statusCode" : 200
 *         } 
 * } ]
 */
4.5.8.3 Duration

When the MediaResource.getMediaProperty operation is invoked with "duration" as a value of the propertyName parameter, an object implementing the Duration interface is returned representing the duration property (defined in the Ontology for Media Resources 1.0 specification).

interface Duration : MediaAnnotation {
    attribute double duration;
};
4.5.8.3.1 Attributes
duration of type double
This attribute represents the duration of the media resource (in seconds) as an double value.
No exceptions.
4.5.8.3.2 Example in Javascript
duration = video.getMediaProperty(["duration"]);
                    
/** Resulting in:
 * [ { "Duration" : {
 *         "propertyName" : "duration",
 *         "duration" : 3600,                    
 *         "statusCode" : 200
 *         } 
 * } ]
 */
4.5.8.4 Format

When the MediaResource.getMediaProperty operation is invoked with "format" as a value of the propertyName parameter, an object implementing the Format interface is returned representing the format property (defined in the Ontology for Media Resources 1.0 specification).

interface Format : MediaAnnotation {
    attribute DOMString formatLink;
    attribute DOMString formatLabel;
};
4.5.8.4.1 Attributes
formatLabel of type DOMString
This attribute specifies the MIME type of the media resource.
No exceptions.
This attribute identifies the MIME type of the media resource by a URI.
No exceptions.
4.5.8.4.2 Example in Javascript
format = image.getMediaProperty(["format"]);

/** Resulting in:
 * [ { "Format" : {
 *         "propertyName" : "format",
 *         "formatLabel" : "image/jpeg",
 *         "formatLink" : "http://dbpedia.org/resource/JPEG",                    
 *         "statusCode" : 200
 *         } 
 * } ]
 */
4.5.8.5 SamplingRate

When the MediaResource.getMediaProperty operation is invoked with "samplingRate" as a value of the propertyName parameter, an object implementing the SamplingRate interface is returned representing the samplingRate property (defined in the Ontology for Media Resources 1.0 specification).

interface SamplingRate : MediaAnnotation {
    attribute double samplingRate;
};
4.5.8.5.1 Attributes
samplingRate of type double
This attribute specifies the samplingrate (in Hz) as a double.
No exceptions.
4.5.8.5.2 Example in Javascript
samplingrate = audio.getMediaProperty(["samplingRate"]);

/** Resulting in:
 * [ { "SamplingRate" : {
 *         "propertyName" : "samplingRate",
 *         "samplingRate" : 44100,                    
 *         "statusCode" : 200
 *         } 
 * } ]
 */
4.5.8.6 FrameRate

When the MediaResource.getMediaProperty operation is invoked with "frameRate" as a value of the propertyName parameter, an object implementing the FrameRate interface is returned representing the frameRate property (defined in the Ontology for Media Resources 1.0 specification).

interface FrameRate : MediaAnnotation {
    attribute double frameRate;
};
4.5.8.6.1 Attributes
frameRate of type double
This attribute specifies the framerate (in fps) as a double value.
No exceptions.
4.5.8.6.2 Example in Javascript
framerate = video.getMediaProperty(["frameRate"]);

/** Resulting in:
 * [ { "FrameRate" : {
 *         "propertyName" : "frameRate",
 *         "frameRate" : 30,                    
 *         "statusCode" : 200
 *         } 
 * } ]
 */
4.5.8.7 AverageBitRate

When the MediaResource.getMediaProperty operation is invoked with "averageBitRate" as a value of the propertyName parameter, an object implementing the AverageBitRate interface is returned representing the averageBitRate property (defined in the Ontology for Media Resources 1.0 specification).

interface AverageBitRate : MediaAnnotation {
    attribute double averageBitRate;
};
4.5.8.7.1 Attributes
averageBitRate of type double
This attribute specifies the average bitrate (in kbps) as a double value.
No exceptions.
4.5.8.7.2 Example in Javascript
bitrate = video.getMediaProperty(["averageBitRate"]);

/** Resulting in:
 * [ { "AverageBitRate" : {
 *         "propertyName" : "averageBitRate",
 *         "averageBitRate" : 45.06,                    
 *         "statusCode" : 200
 *         }
 * } ]
 */
4.5.8.8 NumTracks

When the MediaResource.getMediaProperty operation is invoked with "numTracks" as a value of the propertyName parameter, an object implementing the NumTracks interface is returned representing the numTracks property (defined in the Ontology for Media Resources 1.0 specification).

interface NumTracks : MediaAnnotation {
    attribute short     number;
    attribute DOMString typeString;
};
4.5.8.8.1 Attributes
number of type short
This attribute specifies the number of tracks as an integer value.
No exceptions.
typeString of type DOMString
This attribute specifies the type of the tracks that are counted as a plain string (e.g., audio, subtitle).
No exceptions.
4.5.8.8.2 Example in Javascript
numTracks = video.getMediaProperty(["numTracks"]);

/** Resulting in:
 * [ { "NumTracks" : {
 *         "propertyName" : "numTracks",
 *         "number" : 2,
 *         "typeString" : "audio",                    
 *         "statusCode" : 200
 *         }
 * } ]
 */

4.6 MetadataSource interface

MetadataSource interface is used to identify other metadata sources.

interface MetadataSource {
    attribute DOMString metadataSource;
    attribute DOMString sourceFormat;
};

4.6.1 Attributes

metadataSource of type DOMString
An URI identifying the metadata source.
No exceptions.
sourceFormat of type DOMString
The name of the actual metadata format. It should use the metadata format identifiers defined in the Ontology for Media Resources 1.0 specification.
No exceptions.

4.6.2 Examples in Javascript

metadataSources = new MetadataSource("http://www.w3.org/2008/WebVideo/Annotations/drafts/metadata_formats/DC_example1.xml","dc");

4.7 API Status Codes

This section introduces a set of status codes for the defined API to indicate the system behavior. As described in section 4.4, the status code is returned as one of the attributes of the MediaAnnotation object returned by a method call to the API. These status codes are used on the API level, and applied to either client side or server side implementations.

Later versions of this document may include additional status codes.

Numerical Code Textual Description Example
200 OK property delivered correctly
204 No Content property retrieved without content
206 Partial Content only a subset of the available data stored in the result set
400 Bad Request syntactical error
404 Not Found the queries resource is not found
415 Unsupported Media Type get duration call on an image data store
462 Property not defined in Source Format location is not defined in MediaRSS
500 Internal Server Error internal library (e.g., extractor) crashes
562 Property not supported a subset of properties implemented

5. Usage examples

5.1 Usage as JavaScript API

This part illustrates some examples how to use this API using JavaScript in actual implementations. Moreover, in these examples it is assumed that the implementation of this API knows where to find the metadata that corresponds to a specific media resource (if necessary the location of the metadata can be configured by the use of the MetadataSource interface). The implementation should provide the mappings of different metadata formats to the core properties of the Ontology for Media Resources 1.0 specification.

Example 1: Return the name of the director of the movie "Apocalypse now".
//search the video array for the one with title "Apocalypse now" 
for (var i = 0; i < mediaResourceVideoArray.length; i++) { 

    //request for the titles of the video, the variable "titles"
    //will be filled with an array of MediaAnnotation objects. 
    titles = mediaResourceVideoArray[i].getMediaProperty(["title"], "", "", ""); 
    
    //check if the request is finished correctly
    if (noErrorStatus(titles[0].statusCode) == true) {

        for (var j = 0; j < titles.length; j++) { 

            //check if the title matches 
            if (titles[j].titleLabel == "Apocalypse Now") {

                //request for the director of the video, the variable "results" 
                //will be filled with an array of MediaAnnotation objects. 
                tempResults = mediaResourceVideoArray[i].getMediaProperty(["contributor"], "", "", "");

                for (var k = 0; k < tempResults.length; k++) {
                    if (tempResults[i].roleLabel == "director") {
                        result = tempResults[i];
                        break;
                    }
                }  
            } 
        } 
    }
}

/** Resulting in:
 * [ { "Contributor" : {
 *         "propertyName" : "contributor",
 *         "value" : "Francis Ford Coppola",
 *         ...,                    
 *         "statusCode" = 200
 *         }
 * } ]
 */ 
Example 2: Retrieve the title of the second song from the album "Joshua Tree" by U2.
//get the id of the second song using the fragments property 
tracks = albumMediaResource.getMediaProperty(["fragment"], "", "", "");
trackIdentifier = tracks[1].identifier; 

//use this identifier to get the mediaResource object that represents the track 
mediaResource = new MediaResource(); 
if (mediaResource.getSupportedModes() == 2 || mediaResource.getSupportedModes() == 3) {
    syncMediaResource = mediaResource.createMediaResource(trackIdentifier, new Array(), 2);
}

//get the title of the track 
title = syncMediaResource.getMediaProperty(["title"], "", "", "");

/** Resulting in:
 * [ { "Title" : {
 *         "propertyName" : "title",
 *         "value" : "I Still Haven't Found What I'm Looking For",
 *         ...,                    
 *         "statusCode" = 200          
 *         } 
 * } ]
 */
Example 3: Return the genre of the movie "Apocalypse Now".
genre = movie.getMediaProperty(["genre"], "", "", "en-us"); 

/** Resulting in: 
 * [ { "Genre" : {
 *         "propertyName" : "genre",
 *         "value" : "Action",
 *         ...,                    
 *         "statusCode" = 200
 *         }
 * },
 * { "Genre" : {
 *         "propertyName" : "genre",
 *         "value" : "Drama",
 *         ...,                    
 *         "statusCode" = 200
 *         }
 * },
 * { ...
 *  } ]
 */

5.2 Usage as Web Service

This part illustrates how this API could be implemented using web services. Note that, Web IDL currently does not provide bindings for web services. The given examples correspond to the examples given in Section 4.5 for each property.

The following examples illustrate how to request values for the different properties.

6. Security Considerations

This specification defines a API to access metadata information related to media resources on the Web. These APIs will provide means for requesting metadata information, which can already be accessed in one or different formats, either as separate document or embedded in media resources. As such, this API introduces no additional security issue.

One should nevertheless note that some metadata could be used to access personal information about someone without declaration of agreement. For example, temporal and geographic information about a media resource could indirectly provide information about its creator.

There are related activities and technical documents in W3C working on this topics, such as Policy Requirements [POLICY-REQS] in DAP WG, ODRL 1.1 [ODRL11], P3P 1.1 [P3P11] and PLING Wiki [PLING-WIKI].

A. Web IDL description

Follow this link to download the WebIDL description as IDL file.

module mawg {

    interface MediaResource {
        short getSupportedModes();
        MediaResource createMediaResource(in DOMString mediaResource,
                          in optional MetadataSource[] metadataSources, in optional short mode);
    };

    interface AsyncMediaResource : MediaResource {
        void getMediaProperty(in DOMString[] propertyNames, in PropertyCallback successCallback,
                          in ErrorCallback errorCallback, in optional DOMString fragment,
                          in optional DOMString sourceFormat, in optional DOMString language );
        void getOriginalMetadata (in DOMString sourceFormat, in MetadataCallback successCallback,
                          in ErrorCallback errorCallback);
    };

    interface PropertyCallback {
        void handleEvent (in MediaAnnotation[] mediaAnnotations);
    };

    interface MetadataCallback {
        void handleEvent (in DOMString[] metadata);
    };

    interface ErrorCallback {
        void handleEvent (in DOMString errorStatus);
    };
    
    interface SyncMediaResource : MediaResource {
        MediaAnnotation[] getMediaProperty(in DOMString[] propertyNames,
                            in optional DOMString fragment, in optional DOMString sourceFormat,
                            in optional DOMString language);
        DOMString[] getOriginalMetadata (in DOMString sourceFormat);
    };
    
    interface MetadataSource {
        attribute DOMString metadataSource;
        attribute DOMString sourceFormat;
    };
    
    interface MediaAnnotation {
        attribute DOMString propertyName;
        attribute DOMString value;
        attribute DOMString language;
        attribute DOMString sourceFormat;
        attribute DOMString fragmentIdentifier;
        attribute DOMString mappingType;
        attribute short     statusCode;
    };

    interface Identifier : MediaAnnotation {
        attribute DOMString identifierLink;
    };

    interface Title : MediaAnnotation {
        attribute DOMString titleLabel;
        attribute DOMString typeLink;
        attribute DOMString typeLabel;
    };

    interface Language : MediaAnnotation {
        attribute DOMString languageLink;
        attribute DOMString languageLabel;
    };  

    interface Locator : MediaAnnotation {
        attribute DOMString locatorLink;
    };

    interface Contributor : MediaAnnotation {
        attribute DOMString contributorLink;
        attribute DOMString contributorLabel;
        attribute DOMString roleLink;
        attribute DOMString roleLabel;
    };

    interface Creator : MediaAnnotation {
        attribute DOMString creatorLink;
        attribute DOMString creatorLabel;
        attribute DOMString roleLink;
        attribute DOMString roleLabel;
    };

    interface MADate : MediaAnnotation {
        attribute DOMString date; 
        attribute DOMString typeLink;
        attribute DOMString typeLabel;
    };

    interface Location : MediaAnnotation {
        attribute DOMString locationLink;
        attribute DOMString locationLabel;
        attribute double    longitude;
        attribute double    latitude;
        attribute double    altitude;
        attribute DOMString coordinateSystemLabel;
        attribute DOMString coordinateSystemLink;
    };

    interface Description : MediaAnnotation {
        attribute DOMString descriptionLabel;
    };

    interface Keyword : MediaAnnotation {
        attribute DOMString keywordLink;
        attribute DOMString keywordLabel;
    };

    interface Genre : MediaAnnotation {
        attribute DOMString genreLink;
        attribute DOMString genreLabel;
    };

    interface Rating : MediaAnnotation {
        attribute double ratingValue;
        attribute DOMString ratingSystemLink;
        attribute DOMString ratingSystemLabel;
        attribute double    min;
        attribute double    max; 
    };

    interface Relation : MediaAnnotation {
        attribute DOMString targetLink;
        attribute DOMString targetLabel;
        attribute DOMString typeLink;
        attribute DOMString typeLabel;
    };

    interface Collection : MediaAnnotation {
        attribute DOMString collectionLink;
        attribute DOMString collectionLabel;
    };

    interface Copyright : MediaAnnotation {
        attribute DOMString copyrightLabel;
        attribute DOMString holderLink;
        attribute DOMString holderLabel;
    };

    interface Policy : MediaAnnotation {
        attribute DOMString statementLink;
        attribute DOMString statementLabel;
        attribute DOMString typeLink;
        attribute DOMString typeLabel;
    };

    interface Publisher : MediaAnnotation {
        attribute DOMString publisherLink;
        attribute DOMString publisherLabel;
    };

    interface TargetAudience : MediaAnnotation {
        attribute DOMString audienceLink;
        attribute DOMString audienceLabel;
        attribute DOMString classificationSystemLink;
        attribute DOMString classificationSystemLabel;
    };

    interface Fragment : MediaAnnotation {
        attribute DOMString identifier;
        attribute DOMString roleLink;
        attribute DOMString roleLabel;
    };

    interface NamedFragment : MediaAnnotation {
        attribute DOMString identifier;
        attribute DOMString label;
    };

    interface FrameSize : MediaAnnotation {
        attribute double width;
        attribute double height;
        attribute DOMString unit;
    };

    interface Compression : MediaAnnotation {
        attribute DOMString compressionLink;
        attribute DOMString compressionLabel;
    };

    interface Duration : MediaAnnotation {
        attribute double duration;
    };

    interface Format : MediaAnnotation {
        attribute DOMString formatLink;
        attribute DOMString formatLabel;
    };

    interface SamplingRate : MediaAnnotation {
        attribute double samplingRate;
    };

    interface FrameRate : MediaAnnotation {
        attribute double frameRate;
    }; 

    interface AverageBitRate : MediaAnnotation {
        attribute double averageBitRate;
    };

    interface NumTracks : MediaAnnotation {
        attribute short  number;
        attribute DOMString typeString;
    };
                
};

B. Change log

Note: The following subsections lists all significant changes applied to the API for Media Resources 1.0 specification received in LC.

-- General changes ---

---[LC 2406] 2001-09-10 ---

---[LC 2410] 2001-09-10 ---

---[LC 2419] 2001-09-10 ---

---[LC 2394] 2001-09-10 ---

The following subsection lists all significant changes applied to the API for Media Resources 1.0 specification. These have been decided during the 10th Face-to-face meeting hosted by Apple in Silicon Valley, Ca, USA.

The following subsection lists all significant changes applied to the API for Media Resources 1.0 specification. These have been decided during the 12th Face-to-face meeting hosted by JOANNEUM, Graz, Austria.

C. Acknowledgements

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 ((public) Invited expert), Eric Carlson (Apple, Inc.), Pierre-Antoine Champin (Université de Lyon), Ashish Chawla ((public) Invited expert), Jaime Delgado (Universitat Politècnica de Catalunya), Jean-Pierre Evain ((public) Invited expert), Martin Höffernig (JOANNEUM RESEARCH), Philip Jägenstedt (Opera Software), Ralf Klamma ((public) Invited expert), WonSuk Lee (Samsung Electronics Co., Ltd.), 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), Victor Rodríguez (Universitat Politècnica de Catalunya), Felix Sasaki (DFKI GmbH), David Singer (Apple, Inc.), Florian Stegmaier ((public) Invited expert), John Strassner ((public) Invited expert), Joakim Söderberg (ERICSSON), Mari Carmen Suárez-Figueroa ((public) Invited expert) Thai Wey Then (Apple, Inc.), Ruben Tous (Universitat Politècnica de Catalunya), Raphaël Troncy (EURECOM), 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.

D. References

D.1 Normative references

[MEDIA-FRAGMENTS]
Raphael Troncy; Erik Mannens; Silvia Pfeiffer and Davy Van Deursen. Media Fragments URI 1.0. W3C Working Draft 17 March 2011. URL: http://www.w3.org/TR/2011/WD-media-frags-20110317/
[RFC2119]
S. Bradner. Key words for use in RFCs to Indicate Requirement Levels. March 1997. Internet RFC 2119. URL: http://www.ietf.org/rfc/rfc2119.txt
[WEBIDL]
Cameron McCormack. Web IDL. 19 December 2008. W3C Working Draft. (Work in progress.) URL: http://www.w3.org/TR/2008/WD-WebIDL-20081219

D.2 Informative references

[BCP47]
A. Phillips; M. Davis. Tags for Identifying Languages September 2009. IETF Best Current Practice. URL: http://tools.ietf.org/html/bcp47
[MEDIA-ANNOT-REQS]
WonSuk Lee; Felix Sasaki; Tobias Bürger; Véronique Malaisé. Use Cases and Requirements for Ontology and API for Media Object 1.0.W3C Working Draft 21 January 2010. URL: http://www.w3.org/TR/2010/WD-media-annot-reqs-20100121/
[ODRL11]
Renato Iannella. Open Digital Rights Language (ODRL) Version 1.1. W3C Note. 19 September 2002. URL: http://www.w3.org/TR/odrl
[P3P11]
Matthias Schunter; Rigo Wenning. The Platform for Privacy Preferences 1.1 (P3P1.1) Specification. 13 November 2006. W3C Note. URL: http://www.w3.org/TR/2006/NOTE-P3P11-20061113
[PLING-WIKI]
Policy Languages Interest Group (PLING). PLING Wiki. URL: http://www.w3.org/Policy/pling/
[POLICY-REQS]
Laura Arribas; Paddy Byers; Marcin Hanclik; Frederick Hirsch; David Rogers. Device API Policy Requirements. 13 April 2010. W3C Editor's Draft. (Work in progress.) URL: http://dev.w3.org/2009/dap/policy-reqs/