diff options
Diffstat (limited to 'doc/rfc/rfc8846.txt')
| -rw-r--r-- | doc/rfc/rfc8846.txt | 3262 |
1 files changed, 3262 insertions, 0 deletions
diff --git a/doc/rfc/rfc8846.txt b/doc/rfc/rfc8846.txt new file mode 100644 index 0000000..05b5d74 --- /dev/null +++ b/doc/rfc/rfc8846.txt @@ -0,0 +1,3262 @@ + + + + +Internet Engineering Task Force (IETF) R. Presta +Request for Comments: 8846 S P. Romano +Category: Standards Track University of Napoli +ISSN: 2070-1721 January 2021 + + + An XML Schema for the Controlling Multiple Streams for Telepresence + (CLUE) Data Model + +Abstract + + This document provides an XML schema file for the definition of CLUE + data model types. The term "CLUE" stands for "Controlling Multiple + Streams for Telepresence" and is the name of the IETF working group + in which this document, as well as other companion documents, has + been developed. The document defines a coherent structure for + information associated with the description of a telepresence + scenario. + +Status of This Memo + + This is an Internet Standards Track document. + + This document is a product of the Internet Engineering Task Force + (IETF). It represents the consensus of the IETF community. It has + received public review and has been approved for publication by the + Internet Engineering Steering Group (IESG). Further information on + Internet Standards is available in Section 2 of RFC 7841. + + Information about the current status of this document, any errata, + and how to provide feedback on it may be obtained at + https://www.rfc-editor.org/info/rfc8846. + +Copyright Notice + + Copyright (c) 2021 IETF Trust and the persons identified as the + document authors. All rights reserved. + + This document is subject to BCP 78 and the IETF Trust's Legal + Provisions Relating to IETF Documents + (https://trustee.ietf.org/license-info) in effect on the date of + publication of this document. Please review these documents + carefully, as they describe your rights and restrictions with respect + to this document. Code Components extracted from this document must + include Simplified BSD License text as described in Section 4.e of + the Trust Legal Provisions and are provided without warranty as + described in the Simplified BSD License. + +Table of Contents + + 1. Introduction + 2. Terminology + 3. Definitions + 4. XML Schema + 5. <mediaCaptures> + 6. <encodingGroups> + 7. <captureScenes> + 8. <simultaneousSets> + 9. <globalViews> + 10. <captureEncodings> + 11. <mediaCapture> + 11.1. captureID Attribute + 11.2. mediaType Attribute + 11.3. <captureSceneIDREF> + 11.4. <encGroupIDREF> + 11.5. <spatialInformation> + 11.5.1. <captureOrigin> + 11.5.2. <captureArea> + 11.6. <nonSpatiallyDefinable> + 11.7. <content> + 11.8. <synchronizationID> + 11.9. <allowSubsetChoice> + 11.10. <policy> + 11.11. <maxCaptures> + 11.12. <individual> + 11.13. <description> + 11.14. <priority> + 11.15. <lang> + 11.16. <mobility> + 11.17. <relatedTo> + 11.18. <view> + 11.19. <presentation> + 11.20. <embeddedText> + 11.21. <capturedPeople> + 11.21.1. <personIDREF> + 12. Audio Captures + 12.1. <sensitivityPattern> + 13. Video Captures + 14. Text Captures + 15. Other Capture Types + 16. <captureScene> + 16.1. <sceneInformation> + 16.2. <sceneViews> + 16.3. sceneID Attribute + 16.4. scale Attribute + 17. <sceneView> + 17.1. <mediaCaptureIDs> + 17.2. sceneViewID Attribute + 18. <encodingGroup> + 18.1. <maxGroupBandwidth> + 18.2. <encodingIDList> + 18.3. encodingGroupID Attribute + 19. <simultaneousSet> + 19.1. setID Attribute + 19.2. mediaType Attribute + 19.3. <mediaCaptureIDREF> + 19.4. <sceneViewIDREF> + 19.5. <captureSceneIDREF> + 20. <globalView> + 21. <people> + 21.1. <person> + 21.1.1. personID Attribute + 21.1.2. <personInfo> + 21.1.3. <personType> + 22. <captureEncoding> + 22.1. <captureID> + 22.2. <encodingID> + 22.3. <configuredContent> + 23. <clueInfo> + 24. XML Schema Extensibility + 24.1. Example of Extension + 25. Security Considerations + 26. IANA Considerations + 26.1. XML Namespace Registration + 26.2. XML Schema Registration + 26.3. Media Type Registration for "application/clue_info+xml" + 26.4. Registry for Acceptable <view> Values + 26.5. Registry for Acceptable <presentation> Values + 26.6. Registry for Acceptable <sensitivityPattern> Values + 26.7. Registry for Acceptable <personType> Values + 27. Sample XML File + 28. MCC Example + 29. References + 29.1. Normative References + 29.2. Informative References + Acknowledgements + Authors' Addresses + +1. Introduction + + This document provides an XML schema file for the definition of CLUE + data model types. For the benefit of the reader, the term "CLUE" + stands for "Controlling Multiple Streams for Telepresence" and is the + name of the IETF working group in which this document, as well as + other companion documents, has been developed. A thorough definition + of the CLUE framework can be found in [RFC8845]. + + The schema is based on information contained in [RFC8845]. It + encodes information and constraints defined in the aforementioned + document in order to provide a formal representation of the concepts + therein presented. + + The document specifies the definition of a coherent structure for + information associated with the description of a telepresence + scenario. Such information is used within the CLUE protocol messages + [RFC8847], enabling the dialogue between a Media Provider and a Media + Consumer. CLUE protocol messages, indeed, are XML messages allowing + (i) a Media Provider to advertise its telepresence capabilities in + terms of media captures, capture scenes, and other features + envisioned in the CLUE framework, according to the format herein + defined and (ii) a Media Consumer to request the desired telepresence + options in the form of capture encodings, represented as described in + this document. + +2. Terminology + + The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", + "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and + "OPTIONAL" in this document are to be interpreted as described in + BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all + capitals, as shown here. + +3. Definitions + + This document refers to the same definitions used in [RFC8845], + except for the "CLUE Participant" definition. We briefly recall + herein some of the main terms used in the document. + + Audio Capture: Media Capture for audio. Denoted as "ACn" in the + examples in this document. + + Capture: Same as Media Capture. + + Capture Device: A device that converts physical input, such as + audio, video, or text, into an electrical signal, in most cases to + be fed into a media encoder. + + Capture Encoding: A specific encoding of a Media Capture, to be sent + by a Media Provider to a Media Consumer via RTP. + + Capture Scene: A structure representing a spatial region captured by + one or more Capture Devices, each capturing media representing a + portion of the region. The spatial region represented by a + Capture Scene may correspond to a real region in physical space, + such as a room. A Capture Scene includes attributes and one or + more Capture Scene Views, with each view including one or more + Media Captures. + + Capture Scene View (CSV): A list of Media Captures of the same media + type that together form one way to represent the entire Capture + Scene. + + CLUE Participant: This term is imported from the CLUE protocol + document [RFC8847]. + + Consumer: Short for Media Consumer. + + Encoding or Individual Encoding: A set of parameters representing a + way to encode a Media Capture to become a Capture Encoding. + + Encoding Group: A set of encoding parameters representing a total + media encoding capability to be subdivided across potentially + multiple Individual Encodings. + + Endpoint: A CLUE-capable device that is the logical point of final + termination through receiving, decoding and rendering, and/or + initiation through capturing, encoding, and sending of media + streams. An endpoint consists of one or more physical devices + that source and sink media streams, and exactly one participant + [RFC4353] (which, in turn, includes exactly one SIP User Agent). + Endpoints can be anything from multiscreen/multicamera rooms to + handheld devices. + + Media: Any data that, after suitable encoding, can be conveyed over + RTP, including audio, video, or timed text. + + Media Capture: A source of Media, such as from one or more Capture + Devices or constructed from other media streams. + + Media Consumer: A CLUE-capable device that intends to receive + Capture Encodings. + + Media Provider: A CLUE-capable device that intends to send Capture + Encodings. + + Multiple Content Capture (MCC): A Capture that mixes and/or switches + other Captures of a single type (for example, all audio or all + video). Particular Media Captures may or may not be present in + the resultant Capture Encoding depending on time or space. + Denoted as "MCCn" in the example cases in this document. + + Multipoint Control Unit (MCU): A CLUE-capable device that connects + two or more endpoints together into one single multimedia + conference [RFC7667]. An MCU includes a Mixer, similar to those + in [RFC4353], but without the requirement to send media to each + participant. + + Plane of Interest: The spatial plane within a scene containing the + most-relevant subject matter. + + Provider: Same as a Media Provider. + + Render: The process of generating a representation from Media, such + as displayed motion video or sound emitted from loudspeakers. + + Scene: Same as a Capture Scene. + + Simultaneous Transmission Set: A set of Media Captures that can be + transmitted simultaneously from a Media Provider. + + Single Media Capture: A capture that contains media from a single + source capture device, e.g., an audio capture from a single + microphone or a video capture from a single camera. + + Spatial Relation: The arrangement of two objects in space, in + contrast to relation in time or other relationships. + + Stream: A Capture Encoding sent from a Media Provider to a Media + Consumer via RTP [RFC3550]. + + Stream Characteristics: The media stream attributes commonly used in + non-CLUE SIP/SDP environments (such as media codec, bitrate, + resolution, profile/level, etc.) as well as CLUE-specific + attributes, such as the Capture ID or a spatial location. + + Video Capture: A Media Capture for video. + +4. XML Schema + + This section contains the XML schema for the CLUE data model + definition. + + The element and attribute definitions are formal representations of + the concepts needed to describe the capabilities of a Media Provider + and the streams that are requested by a Media Consumer given the + Media Provider's ADVERTISEMENT [RFC8847]. + + The main groups of information are: + + <mediaCaptures>: the list of media captures available (Section 5) + + <encodingGroups>: the list of encoding groups (Section 6) + + <captureScenes>: the list of capture scenes (Section 7) + + <simultaneousSets>: the list of simultaneous transmission sets + (Section 8) + + <globalViews>: the list of global views sets (Section 9) + + <people>: metadata about the participants represented in the + telepresence session (Section 21) + + <captureEncodings>: the list of instantiated capture encodings + (Section 10) + + All of the above refer to concepts that have been introduced in + [RFC8845] and further detailed in this document. + + <?xml version="1.0" encoding="UTF-8" ?> + <xs:schema + targetNamespace="urn:ietf:params:xml:ns:clue-info" + xmlns:tns="urn:ietf:params:xml:ns:clue-info" + xmlns:xs="http://www.w3.org/2001/XMLSchema" + xmlns="urn:ietf:params:xml:ns:clue-info" + xmlns:xcard="urn:ietf:params:xml:ns:vcard-4.0" + elementFormDefault="qualified" + attributeFormDefault="unqualified" + version="1.0"> + + <!-- Import xCard XML schema --> + <xs:import namespace="urn:ietf:params:xml:ns:vcard-4.0" + schemaLocation= + "https://www.iana.org/assignments/xml-registry/schema/ + vcard-4.0.xsd"/> + + <!-- ELEMENT DEFINITIONS --> + <xs:element name="mediaCaptures" type="mediaCapturesType"/> + <xs:element name="encodingGroups" type="encodingGroupsType"/> + <xs:element name="captureScenes" type="captureScenesType"/> + <xs:element name="simultaneousSets" type="simultaneousSetsType"/> + <xs:element name="globalViews" type="globalViewsType"/> + <xs:element name="people" type="peopleType"/> + + <xs:element name="captureEncodings" type="captureEncodingsType"/> + + + <!-- MEDIA CAPTURES TYPE --> + <!-- envelope of media captures --> + <xs:complexType name="mediaCapturesType"> + <xs:sequence> + <xs:element name="mediaCapture" type="mediaCaptureType" + maxOccurs="unbounded"/> + </xs:sequence> + </xs:complexType> + + + <!-- DESCRIPTION element --> + <xs:element name="description"> + <xs:complexType> + <xs:simpleContent> + <xs:extension base="xs:string"> + <xs:attribute name="lang" type="xs:language"/> + </xs:extension> + </xs:simpleContent> + </xs:complexType> + </xs:element> + + <!-- MEDIA CAPTURE TYPE --> + <xs:complexType name="mediaCaptureType" abstract="true"> + <xs:sequence> + <!-- mandatory fields --> + <xs:element name="captureSceneIDREF" type="xs:IDREF"/> + <xs:choice> + <xs:sequence> + <xs:element name="spatialInformation" + type="tns:spatialInformationType"/> + </xs:sequence> + <xs:element name="nonSpatiallyDefinable" type="xs:boolean" + fixed="true"/> + </xs:choice> + <!-- for handling multicontent captures: --> + <xs:choice> + <xs:sequence> + <xs:element name="synchronizationID" type="xs:ID" + minOccurs="0"/> + <xs:element name="content" type="contentType" minOccurs="0"/> + <xs:element name="policy" type="policyType" minOccurs="0"/> + <xs:element name="maxCaptures" type="maxCapturesType" + minOccurs="0"/> + <xs:element name="allowSubsetChoice" type="xs:boolean" + minOccurs="0"/> + </xs:sequence> + <xs:element name="individual" type="xs:boolean" fixed="true"/> + </xs:choice> + <!-- optional fields --> + <xs:element name="encGroupIDREF" type="xs:IDREF" minOccurs="0"/> + <xs:element ref="description" minOccurs="0" + maxOccurs="unbounded"/> + <xs:element name="priority" type="xs:unsignedInt" minOccurs="0"/> + <xs:element name="lang" type="xs:language" minOccurs="0" + maxOccurs="unbounded"/> + <xs:element name="mobility" type="mobilityType" + minOccurs="0" /> + <xs:element ref="presentation" minOccurs="0" /> + <xs:element ref="embeddedText" minOccurs="0" /> + <xs:element ref="view" minOccurs="0" /> + <xs:element name="capturedPeople" type="capturedPeopleType" + minOccurs="0"/> + <xs:element name="relatedTo" type="xs:IDREF" minOccurs="0"/> + </xs:sequence> + <xs:attribute name="captureID" type="xs:ID" use="required"/> + <xs:attribute name="mediaType" type="xs:string" use="required"/> + + </xs:complexType> + + <!-- POLICY TYPE --> + <xs:simpleType name="policyType"> + <xs:restriction base="xs:string"> + <xs:pattern value="([a-zA-Z0-9])+[:]([0-9])+"/> + </xs:restriction> + </xs:simpleType> + + <!-- CONTENT TYPE --> + <xs:complexType name="contentType"> + <xs:sequence> + <xs:element name="mediaCaptureIDREF" type="xs:string" + minOccurs="0" maxOccurs="unbounded"/> + <xs:element name="sceneViewIDREF" type="xs:string" + minOccurs="0" maxOccurs="unbounded"/> + <xs:any namespace="##other" processContents="lax" minOccurs="0" + maxOccurs="unbounded"/> + </xs:sequence> + <xs:anyAttribute namespace="##other" processContents="lax"/> + </xs:complexType> + + <!-- MAX CAPTURES TYPE --> + <xs:simpleType name="positiveShort"> + <xs:restriction base="xs:unsignedShort"> + <xs:minInclusive value="1"> + </xs:minInclusive> + </xs:restriction> + </xs:simpleType> + + <xs:complexType name="maxCapturesType"> + <xs:simpleContent> + <xs:extension base="positiveShort"> + <xs:attribute name="exactNumber" + type="xs:boolean"/> + </xs:extension> + </xs:simpleContent> + </xs:complexType> + + <!-- CAPTURED PEOPLE TYPE --> + <xs:complexType name="capturedPeopleType"> + <xs:sequence> + <xs:element name="personIDREF" type="xs:IDREF" + maxOccurs="unbounded"/> + </xs:sequence> + </xs:complexType> + + <!-- PEOPLE TYPE --> + <xs:complexType name="peopleType"> + <xs:sequence> + <xs:element name="person" type="personType" maxOccurs="unbounded"/> + </xs:sequence> + </xs:complexType> + + <!-- PERSON TYPE --> + <xs:complexType name="personType"> + <xs:sequence> + <xs:element name="personInfo" type="xcard:vcardType" + maxOccurs="1" minOccurs="0"/> + <xs:element ref="personType" minOccurs="0" + maxOccurs="unbounded" /> + <xs:any namespace="##other" processContents="lax" minOccurs="0" + maxOccurs="unbounded"/> + </xs:sequence> + <xs:attribute name="personID" type="xs:ID" use="required"/> + <xs:anyAttribute namespace="##other" processContents="lax"/> + </xs:complexType> + + <!-- PERSON TYPE ELEMENT --> + <xs:element name="personType" type="xs:string"> + <xs:annotation> + <xs:documentation> + Acceptable values (enumerations) for this type are managed + by IANA in the "CLUE Schema <personType>" registry, + accessible at https://www.iana.org/assignments/clue. + </xs:documentation> + </xs:annotation> + </xs:element> + + <!-- VIEW ELEMENT --> + <xs:element name="view" type="xs:string"> + <xs:annotation> + <xs:documentation> + Acceptable values (enumerations) for this type are managed + by IANA in the "CLUE Schema <view>" registry, + accessible at https://www.iana.org/assignments/clue. + </xs:documentation> + </xs:annotation> + </xs:element> + + <!-- PRESENTATION ELEMENT --> + <xs:element name="presentation" type="xs:string"> + <xs:annotation> + <xs:documentation> + Acceptable values (enumerations) for this type are managed + by IANA in the "CLUE Schema <presentation>" registry, + accessible at https://www.iana.org/assignments/clue. + </xs:documentation> + </xs:annotation> + </xs:element> + + <!-- SPATIAL INFORMATION TYPE --> + <xs:complexType name="spatialInformationType"> + <xs:sequence> + <xs:element name="captureOrigin" type="captureOriginType" + minOccurs="0"/> + <xs:element name="captureArea" type="captureAreaType" + minOccurs="0"/> + <xs:any namespace="##other" processContents="lax" minOccurs="0" + maxOccurs="unbounded"/> + </xs:sequence> + <xs:anyAttribute namespace="##other" processContents="lax"/> + </xs:complexType> + + + <!-- POINT TYPE --> + <xs:complexType name="pointType"> + <xs:sequence> + <xs:element name="x" type="xs:decimal"/> + <xs:element name="y" type="xs:decimal"/> + <xs:element name="z" type="xs:decimal"/> + </xs:sequence> + </xs:complexType> + + <!-- CAPTURE ORIGIN TYPE --> + <xs:complexType name="captureOriginType"> + <xs:sequence> + <xs:element name="capturePoint" type="pointType"></xs:element> + <xs:element name="lineOfCapturePoint" type="pointType" + minOccurs="0"> + </xs:element> + </xs:sequence> + <xs:anyAttribute namespace="##any" processContents="lax"/> + </xs:complexType> + + + <!-- CAPTURE AREA TYPE --> + <xs:complexType name="captureAreaType"> + <xs:sequence> + <xs:element name="bottomLeft" type="pointType"/> + <xs:element name="bottomRight" type="pointType"/> + <xs:element name="topLeft" type="pointType"/> + <xs:element name="topRight" type="pointType"/> + </xs:sequence> + </xs:complexType> + + + <!-- MOBILITY TYPE --> + <xs:simpleType name="mobilityType"> + <xs:restriction base="xs:string"> + <xs:enumeration value="static" /> + <xs:enumeration value="dynamic" /> + <xs:enumeration value="highly-dynamic" /> + </xs:restriction> + </xs:simpleType> + + <!-- TEXT CAPTURE TYPE --> + <xs:complexType name="textCaptureType"> + <xs:complexContent> + <xs:extension base="tns:mediaCaptureType"> + <xs:sequence> + <xs:any namespace="##other" processContents="lax" minOccurs="0" + maxOccurs="unbounded"/> + </xs:sequence> + <xs:anyAttribute namespace="##other" processContents="lax"/> + </xs:extension> + </xs:complexContent> + </xs:complexType> + + + <!-- OTHER CAPTURE TYPE --> + <xs:complexType name="otherCaptureType"> + <xs:complexContent> + <xs:extension base="tns:mediaCaptureType"> + <xs:sequence> + <xs:any namespace="##other" processContents="lax" minOccurs="0" + maxOccurs="unbounded"/> + </xs:sequence> + <xs:anyAttribute namespace="##other" processContents="lax"/> + </xs:extension> + </xs:complexContent> + </xs:complexType> + + <!-- AUDIO CAPTURE TYPE --> + <xs:complexType name="audioCaptureType"> + <xs:complexContent> + <xs:extension base="tns:mediaCaptureType"> + <xs:sequence> + <xs:element ref="sensitivityPattern" minOccurs="0" /> + <xs:any namespace="##other" processContents="lax" minOccurs="0" + maxOccurs="unbounded"/> + </xs:sequence> + <xs:anyAttribute namespace="##other" processContents="lax"/> + </xs:extension> + </xs:complexContent> + </xs:complexType> + + + <!-- SENSITIVITY PATTERN ELEMENT --> + <xs:element name="sensitivityPattern" type="xs:string"> + <xs:annotation> + <xs:documentation> + Acceptable values (enumerations) for this type are managed by + IANA in the "CLUE Schema <sensitivityPattern>" registry, + accessible at https://www.iana.org/assignments/clue. + </xs:documentation> + </xs:annotation> + </xs:element> + + + <!-- VIDEO CAPTURE TYPE --> + <xs:complexType name="videoCaptureType"> + <xs:complexContent> + <xs:extension base="tns:mediaCaptureType"> + <xs:sequence> + <xs:any namespace="##other" processContents="lax" minOccurs="0" + maxOccurs="unbounded"/> + </xs:sequence> + <xs:anyAttribute namespace="##other" processContents="lax"/> + </xs:extension> + </xs:complexContent> + </xs:complexType> + + <!-- EMBEDDED TEXT ELEMENT --> + <xs:element name="embeddedText"> + <xs:complexType> + <xs:simpleContent> + <xs:extension base="xs:boolean"> + <xs:attribute name="lang" type="xs:language"/> + </xs:extension> + </xs:simpleContent> + </xs:complexType> + </xs:element> + + <!-- CAPTURE SCENES TYPE --> + <!-- envelope of capture scenes --> + <xs:complexType name="captureScenesType"> + <xs:sequence> + <xs:element name="captureScene" type="captureSceneType" + maxOccurs="unbounded"/> + </xs:sequence> + </xs:complexType> + + <!-- CAPTURE SCENE TYPE --> + <xs:complexType name="captureSceneType"> + <xs:sequence> + <xs:element ref="description" minOccurs="0" maxOccurs="unbounded"/> + <xs:element name="sceneInformation" type="xcard:vcardType" + minOccurs="0"/> + <xs:element name="sceneViews" type="sceneViewsType" minOccurs="0"/> + <xs:any namespace="##other" processContents="lax" minOccurs="0" + maxOccurs="unbounded"/> + </xs:sequence> + <xs:attribute name="sceneID" type="xs:ID" use="required"/> + <xs:attribute name="scale" type="scaleType" use="required"/> + <xs:anyAttribute namespace="##other" processContents="lax"/> + </xs:complexType> + + <!-- SCALE TYPE --> + <xs:simpleType name="scaleType"> + <xs:restriction base="xs:string"> + <xs:enumeration value="mm"/> + <xs:enumeration value="unknown"/> + <xs:enumeration value="noscale"/> + </xs:restriction> + </xs:simpleType> + + <!-- SCENE VIEWS TYPE --> + <!-- envelope of scene views of a capture scene --> + <xs:complexType name="sceneViewsType"> + <xs:sequence> + <xs:element name="sceneView" type="sceneViewType" + maxOccurs="unbounded"/> + </xs:sequence> + </xs:complexType> + + <!-- SCENE VIEW TYPE --> + <xs:complexType name="sceneViewType"> + <xs:sequence> + <xs:element ref="description" minOccurs="0" maxOccurs="unbounded"/> + <xs:element name="mediaCaptureIDs" type="captureIDListType"/> + </xs:sequence> + <xs:attribute name="sceneViewID" type="xs:ID" use="required"/> + </xs:complexType> + + + <!-- CAPTURE ID LIST TYPE --> + <xs:complexType name="captureIDListType"> + <xs:sequence> + <xs:element name="mediaCaptureIDREF" type="xs:IDREF" + maxOccurs="unbounded"/> + </xs:sequence> + </xs:complexType> + + <!-- ENCODING GROUPS TYPE --> + <xs:complexType name="encodingGroupsType"> + <xs:sequence> + <xs:element name="encodingGroup" type="tns:encodingGroupType" + maxOccurs="unbounded"/> + </xs:sequence> + </xs:complexType> + + <!-- ENCODING GROUP TYPE --> + <xs:complexType name="encodingGroupType"> + <xs:sequence> + <xs:element name="maxGroupBandwidth" type="xs:unsignedLong"/> + <xs:element name="encodingIDList" type="encodingIDListType"/> + <xs:any namespace="##other" processContents="lax" minOccurs="0" + maxOccurs="unbounded"/> + </xs:sequence> + <xs:attribute name="encodingGroupID" type="xs:ID" use="required"/> + <xs:anyAttribute namespace="##any" processContents="lax"/> + </xs:complexType> + + <!-- ENCODING ID LIST TYPE --> + <xs:complexType name="encodingIDListType"> + <xs:sequence> + <xs:element name="encodingID" type="xs:string" + maxOccurs="unbounded"/> + </xs:sequence> + </xs:complexType> + + <!-- SIMULTANEOUS SETS TYPE --> + <xs:complexType name="simultaneousSetsType"> + <xs:sequence> + <xs:element name="simultaneousSet" type="simultaneousSetType" + maxOccurs="unbounded"/> + </xs:sequence> + </xs:complexType> + + <!-- SIMULTANEOUS SET TYPE --> + <xs:complexType name="simultaneousSetType"> + <xs:sequence> + <xs:element name="mediaCaptureIDREF" type="xs:IDREF" + minOccurs="0" maxOccurs="unbounded"/> + <xs:element name="sceneViewIDREF" type="xs:IDREF" + minOccurs="0" maxOccurs="unbounded"/> + <xs:element name="captureSceneIDREF" type="xs:IDREF" + minOccurs="0" maxOccurs="unbounded"/> + <xs:any namespace="##other" processContents="lax" minOccurs="0" + maxOccurs="unbounded"/> + </xs:sequence> + <xs:attribute name="setID" type="xs:ID" use="required"/> + <xs:attribute name="mediaType" type="xs:string"/> + <xs:anyAttribute namespace="##any" processContents="lax"/> + </xs:complexType> + + <!-- GLOBAL VIEWS TYPE --> + <xs:complexType name="globalViewsType"> + <xs:sequence> + <xs:element name="globalView" type="globalViewType" + maxOccurs="unbounded"/> + </xs:sequence> + </xs:complexType> + + <!-- GLOBAL VIEW TYPE --> + <xs:complexType name="globalViewType"> + <xs:sequence> + <xs:element name="sceneViewIDREF" type="xs:IDREF" + maxOccurs="unbounded"/> + <xs:any namespace="##other" processContents="lax" minOccurs="0" + maxOccurs="unbounded"/> + </xs:sequence> + <xs:attribute name="globalViewID" type="xs:ID"/> + <xs:anyAttribute namespace="##any" processContents="lax"/> + </xs:complexType> + + <!-- CAPTURE ENCODINGS TYPE --> + <xs:complexType name="captureEncodingsType"> + <xs:sequence> + <xs:element name="captureEncoding" type="captureEncodingType" + maxOccurs="unbounded"/> + </xs:sequence> + </xs:complexType> + + <!-- CAPTURE ENCODING TYPE --> + <xs:complexType name="captureEncodingType"> + <xs:sequence> + <xs:element name="captureID" type="xs:string"/> + <xs:element name="encodingID" type="xs:string"/> + <xs:element name="configuredContent" type="contentType" + minOccurs="0"/> + <xs:any namespace="##other" processContents="lax" minOccurs="0" + maxOccurs="unbounded"/> + </xs:sequence> + <xs:attribute name="ID" type="xs:ID" use="required"/> + <xs:anyAttribute namespace="##any" processContents="lax"/> + </xs:complexType> + + <!-- CLUE INFO ELEMENT --> + <xs:element name="clueInfo" type="clueInfoType"/> + + <!-- CLUE INFO TYPE --> + <xs:complexType name="clueInfoType"> + <xs:sequence> + <xs:element ref="mediaCaptures"/> + <xs:element ref="encodingGroups"/> + <xs:element ref="captureScenes"/> + <xs:element ref="simultaneousSets" minOccurs="0"/> + <xs:element ref="globalViews" minOccurs="0"/> + <xs:element ref="people" minOccurs="0"/> + <xs:any namespace="##other" processContents="lax" minOccurs="0" + maxOccurs="unbounded"/> + </xs:sequence> + <xs:attribute name="clueInfoID" type="xs:ID" use="required"/> + <xs:anyAttribute namespace="##other" processContents="lax"/> + </xs:complexType> + </xs:schema> + + The following sections describe the XML schema in more detail. As a + general remark, please notice that optional elements that don't + define what their absence means are intended to be associated with + undefined properties. + +5. <mediaCaptures> + + <mediaCaptures> represents the list of one or more media captures + available at the Media Provider's side. Each media capture is + represented by a <mediaCapture> element (Section 11). + +6. <encodingGroups> + + <encodingGroups> represents the list of the encoding groups organized + on the Media Provider's side. Each encoding group is represented by + an <encodingGroup> element (Section 18). + +7. <captureScenes> + + <captureScenes> represents the list of the capture scenes organized + on the Media Provider's side. Each capture scene is represented by a + <captureScene> element (Section 16). + +8. <simultaneousSets> + + <simultaneousSets> contains the simultaneous sets indicated by the + Media Provider. Each simultaneous set is represented by a + <simultaneousSet> element (Section 19). + +9. <globalViews> + + <globalViews> contains a set of alternative representations of all + the scenes that are offered by a Media Provider to a Media Consumer. + Each alternative is named "global view", and it is represented by a + <globalView> element (Section 20). + +10. <captureEncodings> + + <captureEncodings> is a list of capture encodings. It can represent + the list of the desired capture encodings indicated by the Media + Consumer or the list of instantiated captures on the provider's side. + Each capture encoding is represented by a <captureEncoding> element + (Section 22). + +11. <mediaCapture> + + A media capture is the fundamental representation of a media flow + that is available on the provider's side. Media captures are + characterized by (i) a set of features that are independent from the + specific type of medium and (ii) a set of features that are media + specific. The features that are common to all media types appear + within the media capture type, which has been designed as an abstract + complex type. Media-specific captures, such as video captures, audio + captures, and others, are specializations of that abstract media + capture type, as in a typical generalization-specialization + hierarchy. + + The following is the XML schema definition of the media capture type: + + <!-- MEDIA CAPTURE TYPE --> + <xs:complexType name="mediaCaptureType" abstract="true"> + <xs:sequence> + <!-- mandatory fields --> + <xs:element name="captureSceneIDREF" type="xs:IDREF"/> + <xs:choice> + <xs:sequence> + <xs:element name="spatialInformation" + type="tns:spatialInformationType"/> + </xs:sequence> + <xs:element name="nonSpatiallyDefinable" type="xs:boolean" + fixed="true"/> + </xs:choice> + <!-- for handling multicontent captures: --> + <xs:choice> + <xs:sequence> + <xs:element name="synchronizationID" type="xs:ID" + minOccurs="0"/> + <xs:element name="content" type="contentType" minOccurs="0"/> + <xs:element name="policy" type="policyType" minOccurs="0"/> + <xs:element name="maxCaptures" type="maxCapturesType" + minOccurs="0"/> + <xs:element name="allowSubsetChoice" type="xs:boolean" + minOccurs="0"/> + </xs:sequence> + <xs:element name="individual" type="xs:boolean" fixed="true"/> + </xs:choice> + <!-- optional fields --> + <xs:element name="encGroupIDREF" type="xs:IDREF" minOccurs="0"/> + <xs:element ref="description" minOccurs="0" + maxOccurs="unbounded"/> + <xs:element name="priority" type="xs:unsignedInt" minOccurs="0"/> + <xs:element name="lang" type="xs:language" minOccurs="0" + maxOccurs="unbounded"/> + <xs:element name="mobility" type="mobilityType" minOccurs="0" /> + <xs:element ref="presentation" minOccurs="0" /> + <xs:element ref="embeddedText" minOccurs="0" /> + <xs:element ref="view" minOccurs="0" /> + <xs:element name="capturedPeople" type="capturedPeopleType" + minOccurs="0"/> + <xs:element name="relatedTo" type="xs:IDREF" minOccurs="0"/> + </xs:sequence> + <xs:attribute name="captureID" type="xs:ID" use="required"/> + <xs:attribute name="mediaType" type="xs:string" use="required"/> + </xs:complexType> + +11.1. captureID Attribute + + The "captureID" attribute is a mandatory field containing the + identifier of the media capture. Such an identifier serves as the + way the capture is referenced from other data model elements (e.g., + simultaneous sets, capture encodings, and others via + <mediaCaptureIDREF>). + +11.2. mediaType Attribute + + The "mediaType" attribute is a mandatory attribute specifying the + media type of the capture. Common standard values are "audio", + "video", and "text", as defined in [RFC6838]. Other values can be + provided. It is assumed that implementations agree on the + interpretation of those other values. The "mediaType" attribute is + as generic as possible. Here is why: (i) the basic media capture + type is an abstract one; (ii) "concrete" definitions for the standard + audio, video, and text capture types [RFC6838] have been specified; + (iii) a generic "otherCaptureType" type has been defined; and (iv) + the "mediaType" attribute has been generically defined as a string, + with no particular template. From the considerations above, it is + clear that if one chooses to rely on a brand new media type and wants + to interoperate with others, an application-level agreement is needed + on how to interpret such information. + +11.3. <captureSceneIDREF> + + <captureSceneIDREF> is a mandatory field containing the value of the + identifier of the capture scene the media capture is defined in, + i.e., the value of the sceneID attribute (Section 16.3) of that + capture scene. Indeed, each media capture MUST be defined within one + and only one capture scene. When a media capture is spatially + definable, some spatial information is provided along with it in the + form of point coordinates (see Section 11.5). Such coordinates refer + to the space of coordinates defined for the capture scene containing + the capture. + +11.4. <encGroupIDREF> + + <encGroupIDREF> is an optional field containing the identifier of the + encoding group the media capture is associated with, i.e., the value + of the encodingGroupID attribute (Section 18.3) of that encoding + group. Media captures that are not associated with any encoding + group cannot be instantiated as media streams. + +11.5. <spatialInformation> + + Media captures are divided into two categories: (i) non spatially + definable captures and (ii) spatially definable captures. + + Captures are spatially definable when at least it is possible to + provide (i) the coordinates of the device position within the + telepresence room of origin (capture point) together with its + capturing direction specified by a second point (point on line of + capture) or (ii) the represented area within the telepresence room, + by listing the coordinates of the four coplanar points identifying + the plane of interest (area of capture). The coordinates of the + above mentioned points MUST be expressed according to the coordinate + space of the capture scene the media captures belong to. + + Non spatially definable captures cannot be characterized within the + physical space of the telepresence room of origin. Captures of this + kind are, for example, those related to recordings, text captures, + DVDs, registered presentations, or external streams that are played + in the telepresence room and transmitted to remote sites. + + Spatially definable captures represent a part of the telepresence + room. The captured part of the telepresence room is described by + means of the <spatialInformation> element. By comparing the + <spatialInformation> element of different media captures within the + same capture scene, a consumer can better determine the spatial + relationships between them and render them correctly. Non spatially + definable captures do not embed such elements in their XML + description: they are instead characterized by having the + <nonSpatiallyDefinable> tag set to "true" (see Section 11.6). + + The definition of the spatial information type is the following: + + <!-- SPATIAL INFORMATION TYPE --> + <xs:complexType name="spatialInformationType"> + <xs:sequence> + <xs:element name="captureOrigin" type="captureOriginType" + minOccurs="0"/> + <xs:element name="captureArea" type="captureAreaType" + minOccurs="0"/> + <xs:any namespace="##other" processContents="lax" minOccurs="0" + maxOccurs="unbounded"/> + </xs:sequence> + <xs:anyAttribute namespace="##other" processContents="lax"/> + </xs:complexType> + + The <captureOrigin> contains the coordinates of the capture device + that is taking the capture (i.e., the capture point) as well as, + optionally, the pointing direction (i.e., the point on line of + capture); see Section 11.5.1. + + The <captureArea> is an optional field containing four points + defining the captured area covered by the capture (see + Section 11.5.2). + + The scale of the points coordinates is specified in the scale + attribute (Section 16.4) of the capture scene the media capture + belongs to. Indeed, all the spatially definable media captures + referring to the same capture scene share the same coordinate system + and express their spatial information according to the same scale. + +11.5.1. <captureOrigin> + + The <captureOrigin> element is used to represent the position and + optionally the line of capture of a capture device. <captureOrigin> + MUST be included in spatially definable audio captures, while it is + optional for spatially definable video captures. + + The XML schema definition of the <captureOrigin> element type is the + following: + + <!-- CAPTURE ORIGIN TYPE --> + <xs:complexType name="captureOriginType"> + <xs:sequence> + <xs:element name="capturePoint" type="pointType"/> + <xs:element name="lineOfCapturePoint" type="pointType" + minOccurs="0"/> + </xs:sequence> + <xs:anyAttribute namespace="##any" processContents="lax"/> + </xs:complexType> + + <!-- POINT TYPE --> + <xs:complexType name="pointType"> + <xs:sequence> + <xs:element name="x" type="xs:decimal"/> + <xs:element name="y" type="xs:decimal"/> + <xs:element name="z" type="xs:decimal"/> + </xs:sequence> + </xs:complexType> + + The point type contains three spatial coordinates (x,y,z) + representing a point in the space associated with a certain capture + scene. + + The <captureOrigin> element includes a mandatory <capturePoint> + element and an optional <lineOfCapturePoint> element, both of the + type "pointType". <capturePoint> specifies the three coordinates + identifying the position of the capture device. <lineOfCapturePoint> + is another pointType element representing the "point on line of + capture", which gives the pointing direction of the capture device. + + The coordinates of the point on line of capture MUST NOT be identical + to the capture point coordinates. For a spatially definable video + capture, if the point on line of capture is provided, it MUST belong + to the region between the point of capture and the capture area. For + a spatially definable audio capture, if the point on line of capture + is not provided, the sensitivity pattern should be considered + omnidirectional. + +11.5.2. <captureArea> + + <captureArea> is an optional element that can be contained within the + spatial information associated with a media capture. It represents + the spatial area captured by the media capture. <captureArea> MUST be + included in the spatial information of spatially definable video + captures, while it MUST NOT be associated with audio captures. + + The XML representation of that area is provided through a set of four + point-type elements, <bottomLeft>, <bottomRight>, <topLeft>, and + <topRight>, that MUST be coplanar. The four coplanar points are + identified from the perspective of the capture device. The XML + schema definition is the following: + + <!-- CAPTURE AREA TYPE --> + <xs:complexType name="captureAreaType"> + <xs:sequence> + <xs:element name="bottomLeft" type="pointType"/> + <xs:element name="bottomRight" type="pointType"/> + <xs:element name="topLeft" type="pointType"/> + <xs:element name="topRight" type="pointType"/> + </xs:sequence> + </xs:complexType> + +11.6. <nonSpatiallyDefinable> + + When media captures are non spatially definable, they MUST be marked + with the boolean <nonSpatiallyDefinable> element set to "true", and + no <spatialInformation> MUST be provided. Indeed, + <nonSpatiallyDefinable> and <spatialInformation> are mutually + exclusive tags, according to the <choice> section within the XML + schema definition of the media capture type. + +11.7. <content> + + A media capture can be (i) an individual media capture or (ii) an + MCC. An MCC is made by different captures that can be arranged + spatially (by a composition operation), or temporally (by a switching + operation), or that can result from the orchestration of both the + techniques. If a media capture is an MCC, then it MAY show in its + XML data model representation the <content> element. It is composed + by a list of media capture identifiers ("mediaCaptureIDREF") and + capture scene view identifiers ("sceneViewIDREF"), where the latter + ones are used as shortcuts to refer to multiple capture identifiers. + The referenced captures are used to create the MCC according to a + certain strategy. If the <content> element does not appear in an + MCC, or it has no child elements, then the MCC is assumed to be made + of multiple sources, but no information regarding those sources is + provided. + + <!-- CONTENT TYPE --> + <xs:complexType name="contentType"> + <xs:sequence> + <xs:element name="mediaCaptureIDREF" type="xs:string" + minOccurs="0" maxOccurs="unbounded"/> + <xs:element name="sceneViewIDREF" type="xs:string" + minOccurs="0" maxOccurs="unbounded"/> + <xs:any namespace="##other" processContents="lax" minOccurs="0" + maxOccurs="unbounded"/> + </xs:sequence> + <xs:anyAttribute namespace="##other" processContents="lax"/> + </xs:complexType> + +11.8. <synchronizationID> + + <synchronizationID> is an optional element for multiple content + captures that contains a numeric identifier. Multiple content + captures marked with the same identifier in the <synchronizationID> + contain at all times captures coming from the same sources. It is + the Media Provider that determines what the source is for the + captures. In this way, the Media Provider can choose how to group + together single captures for the purpose of keeping them synchronized + according to the <synchronizationID> element. + +11.9. <allowSubsetChoice> + + <allowSubsetChoice> is an optional boolean element for multiple + content captures. It indicates whether or not the Provider allows + the Consumer to choose a specific subset of the captures referenced + by the MCC. If this attribute is true, and the MCC references other + captures, then the Consumer MAY specify in a CONFIGURE message a + specific subset of those captures to be included in the MCC, and the + Provider MUST then include only that subset. If this attribute is + false, or the MCC does not reference other captures, then the + Consumer MUST NOT select a subset. If <allowSubsetChoice> is not + shown in the XML description of the MCC, its value is to be + considered "false". + +11.10. <policy> + + <policy> is an optional element that can be used only for multiple + content captures. It indicates the criteria applied to build the + multiple content capture using the media captures referenced in the + <mediaCaptureIDREF> list. The <policy> value is in the form of a + token that indicates the policy and an index representing an instance + of the policy, separated by a ":" (e.g., SoundLevel:2, RoundRobin:0, + etc.). The XML schema defining the type of the <policy> element is + the following: + + <!-- POLICY TYPE --> + <xs:simpleType name="policyType"> + <xs:restriction base="xs:string"> + <xs:pattern value="([a-zA-Z0-9])+[:]([0-9])+"/> + </xs:restriction> + </xs:simpleType> + + At the time of writing, only two switching policies are defined; they + are in [RFC8845] as follows: + + | SoundLevel: This indicates that the content of the MCC is + | determined by a sound-level-detection algorithm. The loudest + | (active) speaker (or a previous speaker, depending on the index + | value) is contained in the MCC. + | + | RoundRobin: This indicates that the content of the MCC is + | determined by a time-based algorithm. For example, the + | Provider provides content from a particular source for a period + | of time and then provides content from another source, and so + | on. + + Other values for the <policy> element can be used. In this case, it + is assumed that implementations agree on the meaning of those other + values and/or those new switching policies are defined in later + documents. + +11.11. <maxCaptures> + + <maxCaptures> is an optional element that can be used only for MCCs. + It provides information about the number of media captures that can + be represented in the multiple content capture at a time. If + <maxCaptures> is not provided, all the media captures listed in the + <content> element can appear at a time in the capture encoding. The + type definition is provided below. + + <!-- MAX CAPTURES TYPE --> + <xs:simpleType name="positiveShort"> + <xs:restriction base="xs:unsignedShort"> + <xs:minInclusive value="1"> + </xs:minInclusive> + </xs:restriction> + </xs:simpleType> + + <xs:complexType name="maxCapturesType"> + <xs:simpleContent> + <xs:extension base="positiveShort"> + <xs:attribute name="exactNumber" + type="xs:boolean"/> + </xs:extension> + </xs:simpleContent> + </xs:complexType> + + When the "exactNumber" attribute is set to "true", it means the + <maxCaptures> element carries the exact number of the media captures + appearing at a time. Otherwise, the number of the represented media + captures MUST be considered "<=" the <maxCaptures> value. + + For instance, an audio MCC having the <maxCaptures> value set to 1 + means that a media stream from the MCC will only contain audio from a + single one of its constituent captures at a time. On the other hand, + if the <maxCaptures> value is set to 4 and the exactNumber attribute + is set to "true", it would mean that the media stream received from + the MCC will always contain a mix of audio from exactly four of its + constituent captures. + +11.12. <individual> + + <individual> is a boolean element that MUST be used for single- + content captures. Its value is fixed and set to "true". Such + element indicates the capture that is being described is not an MCC. + Indeed, <individual> and the aforementioned tags related to MCC + attributes (from Sections 11.7 to 11.11) are mutually exclusive, + according to the <choice> section within the XML schema definition of + the media capture type. + +11.13. <description> + + <description> is used to provide human-readable textual information. + This element is included in the XML definition of media captures, + capture scenes, and capture scene views to provide human-readable + descriptions of, respectively, media captures, capture scenes, and + capture scene views. According to the data model definition of a + media capture (Section 11)), zero or more <description> elements can + be used, each providing information in a different language. The + <description> element definition is the following: + + <!-- DESCRIPTION element --> + <xs:element name="description"> + <xs:complexType> + <xs:simpleContent> + <xs:extension base="xs:string"> + <xs:attribute name="lang" type="xs:language"/> + </xs:extension> + </xs:simpleContent> + </xs:complexType> + </xs:element> + + As can be seen, <description> is a string element with an attribute + ("lang") indicating the language used in the textual description. + Such an attribute is compliant with the Language-Tag ABNF production + from [RFC5646]. + +11.14. <priority> + + <priority> is an optional unsigned integer field indicating the + importance of a media capture according to the Media Provider's + perspective. It can be used on the receiver's side to automatically + identify the most relevant contribution from the Media Provider. The + higher the importance, the lower the contained value. If no priority + is assigned, no assumptions regarding relative importance of the + media capture can be assumed. + +11.15. <lang> + + <lang> is an optional element containing the language used in the + capture. Zero or more <lang> elements can appear in the XML + description of a media capture. Each such element has to be + compliant with the Language-Tag ABNF production from [RFC5646]. + +11.16. <mobility> + + <mobility> is an optional element indicating whether or not the + capture device originating the capture may move during the + telepresence session. That optional element can assume one of the + three following values: + + static: SHOULD NOT change for the duration of the CLUE session, + across multiple ADVERTISEMENT messages. + + dynamic: MAY change in each new ADVERTISEMENT message. Can be + assumed to remain unchanged until there is a new ADVERTISEMENT + message. + + highly-dynamic: MAY change dynamically, even between consecutive + ADVERTISEMENT messages. The spatial information provided in an + ADVERTISEMENT message is simply a snapshot of the current + values at the time when the message is sent. + +11.17. <relatedTo> + + The optional <relatedTo> element contains the value of the captureID + attribute (Section 11.1) of the media capture to which the considered + media capture refers. The media capture marked with a <relatedTo> + element can be, for example, the translation of the referred media + capture in a different language. + +11.18. <view> + + The <view> element is an optional tag describing what is represented + in the spatial area covered by a media capture. It has been + specified as a simple string with an annotation pointing to an IANA + registry that is defined ad hoc: + + <!-- VIEW ELEMENT --> + <xs:element name="view" type="xs:string"> + <xs:annotation> + <xs:documentation> + Acceptable values (enumerations) for this type are managed + by IANA in the "CLUE Schema <view>" registry, + accessible at https://www.iana.org/assignments/clue. + </xs:documentation> + </xs:annotation> + </xs:element> + + The current possible values, as per the CLUE framework document + [RFC8845], are: "room", "table", "lectern", "individual", and + "audience". + +11.19. <presentation> + + The <presentation> element is an optional tag used for media captures + conveying information about presentations within the telepresence + session. It has been specified as a simple string with an annotation + pointing to an IANA registry that is defined ad hoc: + + <!-- PRESENTATION ELEMENT --> + <xs:element name="presentation" type="xs:string"> + <xs:annotation> + <xs:documentation> + Acceptable values (enumerations) for this type are managed + by IANA in the "CLUE Schema <presentation>" registry, + accessible at https://www.iana.org/assignments/clue. + </xs:documentation> + </xs:annotation> + </xs:element> + + The current possible values, as per the CLUE framework document + [RFC8845], are "slides" and "images". + +11.20. <embeddedText> + + The <embeddedText> element is a boolean element indicating that there + is text embedded in the media capture (e.g., in a video capture). + The language used in such an embedded textual description is reported + in the <embeddedText> "lang" attribute. + + The XML schema definition of the <embeddedText> element is: + + <!-- EMBEDDED TEXT ELEMENT --> + <xs:element name="embeddedText"> + <xs:complexType> + <xs:simpleContent> + <xs:extension base="xs:boolean"> + <xs:attribute name="lang" type="xs:language"/> + </xs:extension> + </xs:simpleContent> + </xs:complexType> + </xs:element> + +11.21. <capturedPeople> + + This optional element is used to indicate which telepresence session + participants are represented in within the media captures. For each + participant, a <personIDREF> element is provided. + +11.21.1. <personIDREF> + + <personIDREF> contains the identifier of the represented person, + i.e., the value of the related personID attribute (Section 21.1.1). + Metadata about the represented participant can be retrieved by + accessing the <people> list (Section 21). + +12. Audio Captures + + Audio captures inherit all the features of a generic media capture + and present further audio-specific characteristics. The XML schema + definition of the audio capture type is reported below: + + <!-- AUDIO CAPTURE TYPE --> + <xs:complexType name="audioCaptureType"> + <xs:complexContent> + <xs:extension base="tns:mediaCaptureType"> + <xs:sequence> + <xs:element ref="sensitivityPattern" minOccurs="0" /> + <xs:any namespace="##other" processContents="lax" minOccurs="0" + maxOccurs="unbounded"/> + </xs:sequence> + <xs:anyAttribute namespace="##other" processContents="lax"/> + </xs:extension> + </xs:complexContent> + </xs:complexType> + + An example of audio-specific information that can be included is + represented by the <sensitivityPattern> element (Section 12.1). + +12.1. <sensitivityPattern> + + The <sensitivityPattern> element is an optional field describing the + characteristics of the nominal sensitivity pattern of the microphone + capturing the audio signal. It has been specified as a simple string + with an annotation pointing to an IANA registry that is defined ad + hoc: + + <!-- SENSITIVITY PATTERN ELEMENT --> + <xs:element name="sensitivityPattern" type="xs:string"> + <xs:annotation> + <xs:documentation> + Acceptable values (enumerations) for this type are managed by + IANA in the "CLUE Schema <sensitivityPattern>" registry, + accessible at https://www.iana.org/assignments/clue. + </xs:documentation> + </xs:annotation> + </xs:element> + + The current possible values, as per the CLUE framework document + [RFC8845], are "uni", "shotgun", "omni", "figure8", "cardioid", and + "hyper-cardioid". + +13. Video Captures + + Video captures, similarly to audio captures, extend the information + of a generic media capture with video-specific features. + + The XML schema representation of the video capture type is provided + in the following: + + <!-- VIDEO CAPTURE TYPE --> + <xs:complexType name="videoCaptureType"> + <xs:complexContent> + <xs:extension base="tns:mediaCaptureType"> + <xs:sequence> + <xs:any namespace="##other" processContents="lax" minOccurs="0" + maxOccurs="unbounded"/> + </xs:sequence> + <xs:anyAttribute namespace="##other" processContents="lax"/> + </xs:extension> + </xs:complexContent> + </xs:complexType> + +14. Text Captures + + Similar to audio captures and video captures, text captures can be + described by extending the generic media capture information. + + There are no known properties of a text-based media that aren't + already covered by the generic mediaCaptureType. Text captures are + hence defined as follows: + + <!-- TEXT CAPTURE TYPE --> + <xs:complexType name="textCaptureType"> + <xs:complexContent> + <xs:extension base="tns:mediaCaptureType"> + <xs:sequence> + <xs:any namespace="##other" processContents="lax" minOccurs="0" + maxOccurs="unbounded"/> + </xs:sequence> + <xs:anyAttribute namespace="##other" processContents="lax"/> + </xs:extension> + </xs:complexContent> + </xs:complexType> + + Text captures MUST be marked as non spatially definable (i.e., they + MUST present in their XML description the <nonSpatiallyDefinable> + (Section 11.6) element set to "true"). + +15. Other Capture Types + + Other media capture types can be described by using the CLUE data + model. They can be represented by exploiting the "otherCaptureType" + type. This media capture type is conceived to be filled in with + elements defined within extensions of the current schema, i.e., with + elements defined in other XML schemas (see Section 24 for an + example). The otherCaptureType inherits all the features envisioned + for the abstract mediaCaptureType. + + The XML schema representation of the otherCaptureType is the + following: + + <!-- OTHER CAPTURE TYPE --> + <xs:complexType name="otherCaptureType"> + <xs:complexContent> + <xs:extension base="tns:mediaCaptureType"> + <xs:sequence> + <xs:any namespace="##other" processContents="lax" minOccurs="0" + maxOccurs="unbounded"/> + </xs:sequence> + <xs:anyAttribute namespace="##other" processContents="lax"/> + </xs:extension> + </xs:complexContent> + </xs:complexType> + + When defining new media capture types that are going to be described + by means of the <otherMediaCapture> element, spatial properties of + such new media capture types SHOULD be defined (e.g., whether or not + they are spatially definable and whether or not they should be + associated with an area of capture or other properties that may be + defined). + +16. <captureScene> + + A Media Provider organizes the available captures in capture scenes + in order to help the receiver in both the rendering and the selection + of the group of captures. Capture scenes are made of media captures + and capture scene views, which are sets of media captures of the same + media type. Each capture scene view is an alternative to completely + represent a capture scene for a fixed media type. + + The XML schema representation of a <captureScene> element is the + following: + + <!-- CAPTURE SCENE TYPE --> + <xs:complexType name="captureSceneType"> + <xs:sequence> + <xs:element ref="description" minOccurs="0" maxOccurs="unbounded"/> + <xs:element name="sceneInformation" type="xcard:vcardType" + minOccurs="0"/> + <xs:element name="sceneViews" type="sceneViewsType" minOccurs="0"/> + <xs:any namespace="##other" processContents="lax" minOccurs="0" + maxOccurs="unbounded"/> + </xs:sequence> + <xs:attribute name="sceneID" type="xs:ID" use="required"/> + <xs:attribute name="scale" type="scaleType" use="required"/> + <xs:anyAttribute namespace="##other" processContents="lax"/> + </xs:complexType> + + Each capture scene is identified by a "sceneID" attribute. The + <captureScene> element can contain zero or more textual <description> + elements, as defined in Section 11.13. Besides <description>, there + is the optional <sceneInformation> element (Section 16.1), which + contains structured information about the scene in the vCard format, + and the optional <sceneViews> element (Section 16.2), which is the + list of the capture scene views. When no <sceneViews> is provided, + the capture scene is assumed to be made of all the media captures + that contain the value of its sceneID attribute in their mandatory + captureSceneIDREF attribute. + +16.1. <sceneInformation> + + The <sceneInformation> element contains optional information about + the capture scene according to the vCard format, as specified in the + xCard specification [RFC6351]. + +16.2. <sceneViews> + + The <sceneViews> element is a mandatory field of a capture scene + containing the list of scene views. Each scene view is represented + by a <sceneView> element (Section 17). + + <!-- SCENE VIEWS TYPE --> + <!-- envelope of scene views of a capture scene --> + <xs:complexType name="sceneViewsType"> + <xs:sequence> + <xs:element name="sceneView" type="sceneViewType" + maxOccurs="unbounded"/> + </xs:sequence> + </xs:complexType> + +16.3. sceneID Attribute + + The sceneID attribute is a mandatory attribute containing the + identifier of the capture scene. + +16.4. scale Attribute + + The scale attribute is a mandatory attribute that specifies the scale + of the coordinates provided in the spatial information of the media + capture belonging to the considered capture scene. The scale + attribute can assume three different values: + + "mm": the scale is in millimeters. Systems that know their + physical dimensions (for example, professionally installed + telepresence room systems) should always provide such real- + world measurements. + + "unknown": the scale is the same for every media capture in the + capture scene, but the unity of measure is undefined. Systems + that are not aware of specific physical dimensions yet still + know relative distances should select "unknown" in the scale + attribute of the capture scene to be described. + + "noscale": there is no common physical scale among the media + captures of the capture scene. That means the scale could be + different for each media capture. + + <!-- SCALE TYPE --> + <xs:simpleType name="scaleType"> + <xs:restriction base="xs:string"> + <xs:enumeration value="mm"/> + <xs:enumeration value="unknown"/> + <xs:enumeration value="noscale"/> + </xs:restriction> + </xs:simpleType> + +17. <sceneView> + + A <sceneView> element represents a capture scene view, which contains + a set of media captures of the same media type describing a capture + scene. + + A <sceneView> element is characterized as follows. + + <!-- SCENE VIEW TYPE --> + <xs:complexType name="sceneViewType"> + <xs:sequence> + <xs:element ref="description" minOccurs="0" maxOccurs="unbounded"/> + <xs:element name="mediaCaptureIDs" type="captureIDListType"/> + </xs:sequence> + <xs:attribute name="sceneViewID" type="xs:ID" use="required"/> + </xs:complexType> + + One or more optional <description> elements provide human-readable + information about what the scene view contains. <description> is + defined in Section 11.13. + + The remaining child elements are described in the following + subsections. + +17.1. <mediaCaptureIDs> + + <mediaCaptureIDs> is the list of the identifiers of the media + captures included in the scene view. It is an element of the + captureIDListType type, which is defined as a sequence of + <mediaCaptureIDREF>, each containing the identifier of a media + capture listed within the <mediaCaptures> element: + + <!-- CAPTURE ID LIST TYPE --> + <xs:complexType name="captureIDListType"> + <xs:sequence> + <xs:element name="mediaCaptureIDREF" type="xs:IDREF" + maxOccurs="unbounded"/> + </xs:sequence> + </xs:complexType> + +17.2. sceneViewID Attribute + + The sceneViewID attribute is a mandatory attribute containing the + identifier of the capture scene view represented by the <sceneView> + element. + +18. <encodingGroup> + + The <encodingGroup> element represents an encoding group, which is + made by a set of one or more individual encodings and some parameters + that apply to the group as a whole. Encoding groups contain + references to individual encodings that can be applied to media + captures. The definition of the <encodingGroup> element is the + following: + + <!-- ENCODING GROUP TYPE --> + <xs:complexType name="encodingGroupType"> + <xs:sequence> + <xs:element name="maxGroupBandwidth" type="xs:unsignedLong"/> + <xs:element name="encodingIDList" type="encodingIDListType"/> + <xs:any namespace="##other" processContents="lax" minOccurs="0" + maxOccurs="unbounded"/> + </xs:sequence> + <xs:attribute name="encodingGroupID" type="xs:ID" use="required"/> + <xs:anyAttribute namespace="##any" processContents="lax"/> + </xs:complexType> + + In the following subsections, the contained elements are further + described. + +18.1. <maxGroupBandwidth> + + <maxGroupBandwidth> is an optional field containing the maximum + bitrate expressed in bits per second that can be shared by the + individual encodings included in the encoding group. + +18.2. <encodingIDList> + + <encodingIDList> is the list of the individual encodings grouped + together in the encoding group. Each individual encoding is + represented through its identifier contained within an <encodingID> + element. + + <!-- ENCODING ID LIST TYPE --> + <xs:complexType name="encodingIDListType"> + <xs:sequence> + <xs:element name="encodingID" type="xs:string" + maxOccurs="unbounded"/> + </xs:sequence> + </xs:complexType> + +18.3. encodingGroupID Attribute + + The encodingGroupID attribute contains the identifier of the encoding + group. + +19. <simultaneousSet> + + <simultaneousSet> represents a simultaneous transmission set, i.e., a + list of captures of the same media type that can be transmitted at + the same time by a Media Provider. There are different simultaneous + transmission sets for each media type. + + <!-- SIMULTANEOUS SET TYPE --> + <xs:complexType name="simultaneousSetType"> + <xs:sequence> + <xs:element name="mediaCaptureIDREF" type="xs:IDREF" + minOccurs="0" maxOccurs="unbounded"/> + <xs:element name="sceneViewIDREF" type="xs:IDREF" + minOccurs="0" maxOccurs="unbounded"/> + <xs:element name="captureSceneIDREF" type="xs:IDREF" + minOccurs="0" maxOccurs="unbounded"/> + <xs:any namespace="##other" processContents="lax" minOccurs="0" + maxOccurs="unbounded"/> + </xs:sequence> + <xs:attribute name="setID" type="xs:ID" use="required"/> + <xs:attribute name="mediaType" type="xs:string"/> + <xs:anyAttribute namespace="##any" processContents="lax"/> + </xs:complexType> + + Besides the identifiers of the captures (<mediaCaptureIDREF> + elements), the identifiers of capture scene views and capture scenes + can also be exploited as shortcuts (<sceneViewIDREF> and + <captureSceneIDREF> elements). As an example, let's consider the + situation where there are two capture scene views (S1 and S7). S1 + contains captures AC11, AC12, and AC13. S7 contains captures AC71 + and AC72. Provided that AC11, AC12, AC13, AC71, and AC72 can be + simultaneously sent to the Media Consumer, instead of having 5 + <mediaCaptureIDREF> elements listed in the simultaneous set (i.e., + one <mediaCaptureIDREF> for AC11, one for AC12, and so on), there can + be just two <sceneViewIDREF> elements (one for S1 and one for S7). + +19.1. setID Attribute + + The "setID" attribute is a mandatory field containing the identifier + of the simultaneous set. + +19.2. mediaType Attribute + + The "mediaType" attribute is an optional attribute containing the + media type of the captures referenced by the simultaneous set. + + When only capture scene identifiers are listed within a simultaneous + set, the media type attribute MUST appear in the XML description in + order to determine which media captures can be simultaneously sent + together. + +19.3. <mediaCaptureIDREF> + + <mediaCaptureIDREF> contains the identifier of the media capture that + belongs to the simultaneous set. + +19.4. <sceneViewIDREF> + + <sceneViewIDREF> contains the identifier of the scene view containing + a group of captures that are able to be sent simultaneously with the + other captures of the simultaneous set. + +19.5. <captureSceneIDREF> + + <captureSceneIDREF> contains the identifier of the capture scene + where all the included captures of a certain media type are able to + be sent together with the other captures of the simultaneous set. + +20. <globalView> + + <globalView> is a set of captures of the same media type representing + a summary of the complete Media Provider's offer. The content of a + global view is expressed by leveraging only scene view identifiers, + put within <sceneViewIDREF> elements. Each global view is identified + by a unique identifier within the "globalViewID" attribute. + + <!-- GLOBAL VIEW TYPE --> + <xs:complexType name="globalViewType"> + <xs:sequence> + <xs:element name="sceneViewIDREF" type="xs:IDREF" + maxOccurs="unbounded"/> + <xs:any namespace="##other" processContents="lax" minOccurs="0" + maxOccurs="unbounded"/> + </xs:sequence> + <xs:attribute name="globalViewID" type="xs:ID"/> + <xs:anyAttribute namespace="##any" processContents="lax"/> + </xs:complexType> + +21. <people> + + Information about the participants that are represented in the media + captures is conveyed via the <people> element. As it can be seen + from the XML schema depicted below, for each participant, a <person> + element is provided. + + <!-- PEOPLE TYPE --> + <xs:complexType name="peopleType"> + <xs:sequence> + <xs:element name="person" type="personType" maxOccurs="unbounded"/> + </xs:sequence> + </xs:complexType> + +21.1. <person> + + <person> includes all the metadata related to a person represented + within one or more media captures. Such element provides the vCard + of the subject (via the <personInfo> element; see Section 21.1.2) and + its conference role(s) (via one or more <personType> elements; see + Section 21.1.3). Furthermore, it has a mandatory "personID" + attribute (Section 21.1.1). + + <!-- PERSON TYPE --> + <xs:complexType name="personType"> + <xs:sequence> + <xs:element name="personInfo" type="xcard:vcardType" maxOccurs="1" + minOccurs="0"/> + <xs:element ref="personType" minOccurs="0" maxOccurs="unbounded" /> + <xs:any namespace="##other" processContents="lax" minOccurs="0" + maxOccurs="unbounded"/> + </xs:sequence> + <xs:attribute name="personID" type="xs:ID" use="required"/> + <xs:anyAttribute namespace="##other" processContents="lax"/> + </xs:complexType> + +21.1.1. personID Attribute + + The "personID" attribute carries the identifier of a represented + person. Such an identifier can be used to refer to the participant, + as in the <capturedPeople> element in the media captures + representation (Section 11.21). + +21.1.2. <personInfo> + + The <personInfo> element is the XML representation of all the fields + composing a vCard as specified in the xCard document [RFC6351]. The + vcardType is imported by the xCard XML schema provided in Appendix A + of [RFC7852]. As such schema specifies, the <fn> element within + <vcard> is mandatory. + +21.1.3. <personType> + + The value of the <personType> element determines the role of the + represented participant within the telepresence session organization. + It has been specified as a simple string with an annotation pointing + to an IANA registry that is defined ad hoc: + + <!-- PERSON TYPE ELEMENT --> + <xs:element name="personType" type="xs:string"> + <xs:annotation> + <xs:documentation> + Acceptable values (enumerations) for this type are managed + by IANA in the "CLUE Schema <personType>" registry, + accessible at https://www.iana.org/assignments/clue. + </xs:documentation> + </xs:annotation> + </xs:element> + + The current possible values, as per the CLUE framework document + [RFC8845], are: "presenter", "timekeeper", "attendee", "minute + taker", "translator", "chairman", "vice-chairman", and "observer". + + A participant can play more than one conference role. In that case, + more than one <personType> element will appear in its description. + +22. <captureEncoding> + + A capture encoding is given from the association of a media capture + with an individual encoding, to form a capture stream as defined in + [RFC8845]. Capture encodings are used within CONFIGURE messages from + a Media Consumer to a Media Provider for representing the streams + desired by the Media Consumer. For each desired stream, the Media + Consumer needs to be allowed to specify: (i) the capture identifier + of the desired capture that has been advertised by the Media + Provider; (ii) the encoding identifier of the encoding to use, among + those advertised by the Media Provider; and (iii) optionally, in case + of multicontent captures, the list of the capture identifiers of the + desired captures. All the mentioned identifiers are intended to be + included in the ADVERTISEMENT message that the CONFIGURE message + refers to. The XML model of <captureEncoding> is provided in the + following. + + <!-- CAPTURE ENCODING TYPE --> + <xs:complexType name="captureEncodingType"> + <xs:sequence> + <xs:element name="captureID" type="xs:string"/> + <xs:element name="encodingID" type="xs:string"/> + <xs:element name="configuredContent" type="contentType" + minOccurs="0"/> + <xs:any namespace="##other" processContents="lax" minOccurs="0" + maxOccurs="unbounded"/> + </xs:sequence> + <xs:attribute name="ID" type="xs:ID" use="required"/> + <xs:anyAttribute namespace="##any" processContents="lax"/> + </xs:complexType> + +22.1. <captureID> + + <captureID> is the mandatory element containing the identifier of the + media capture that has been encoded to form the capture encoding. + +22.2. <encodingID> + + <encodingID> is the mandatory element containing the identifier of + the applied individual encoding. + +22.3. <configuredContent> + + <configuredContent> is an optional element to be used in case of the + configuration of MCC. It contains the list of capture identifiers + and capture scene view identifiers the Media Consumer wants within + the MCC. That element is structured as the <content> element used to + describe the content of an MCC. The total number of media captures + listed in the <configuredContent> MUST be lower than or equal to the + value carried within the <maxCaptures> attribute of the MCC. + +23. <clueInfo> + + The <clueInfo> element includes all the information needed to + represent the Media Provider's description of its telepresence + capabilities according to the CLUE framework. Indeed, it is made by: + + * the list of the available media captures (see "<mediaCaptures>", + Section 5) + + * the list of encoding groups (see "<encodingGroups>", Section 6) + + * the list of capture scenes (see "<captureScenes>", Section 7) + + * the list of simultaneous transmission sets (see + "<simultaneousSets>", Section 8) + + * the list of global views sets (see "<globalViews>", Section 9) + + * metadata about the participants represented in the telepresence + session (see "<people>", Section 21) + + It has been conceived only for data model testing purposes, and + though it resembles the body of an ADVERTISEMENT message, it is not + actually used in the CLUE protocol message definitions. The + telepresence capabilities descriptions compliant to this data model + specification that can be found in Sections 27 and 28 are provided by + using the <clueInfo> element. + + <!-- CLUE INFO TYPE --> + <xs:complexType name="clueInfoType"> + <xs:sequence> + <xs:element ref="mediaCaptures"/> + <xs:element ref="encodingGroups"/> + <xs:element ref="captureScenes"/> + <xs:element ref="simultaneousSets" minOccurs="0"/> + <xs:element ref="globalViews" minOccurs="0"/> + <xs:element ref="people" minOccurs="0"/> + <xs:any namespace="##other" processContents="lax" minOccurs="0" + maxOccurs="unbounded"/> + </xs:sequence> + <xs:attribute name="clueInfoID" type="xs:ID" use="required"/> + <xs:anyAttribute namespace="##other" processContents="lax"/> + </xs:complexType> + +24. XML Schema Extensibility + + The telepresence data model defined in this document is meant to be + extensible. Extensions are accomplished by defining elements or + attributes qualified by namespaces other than + "urn:ietf:params:xml:ns:clue-info" and "urn:ietf:params:xml:ns:vcard- + 4.0" for use wherever the schema allows such extensions (i.e., where + the XML schema definition specifies "anyAttribute" or "anyElement"). + Elements or attributes from unknown namespaces MUST be ignored. + Extensibility was purposefully favored as much as possible based on + expectations about custom implementations. Hence, the schema offers + people enough flexibility as to define custom extensions, without + losing compliance with the standard. This is achieved by leveraging + <xs:any> elements and <xs:anyAttribute> attributes, which is a common + approach with schemas, while still matching the Unique Particle + Attribution (UPA) constraint. + +24.1. Example of Extension + + When extending the CLUE data model, a new schema with a new namespace + associated with it needs to be specified. + + In the following, an example of extension is provided. The extension + defines a new audio capture attribute ("newAudioFeature") and an + attribute for characterizing the captures belonging to an + "otherCaptureType" defined by the user. An XML document compliant + with the extension is also included. The XML file results are + validated against the current XML schema for the CLUE data model. + + <?xml version="1.0" encoding="UTF-8" ?> + <xs:schema + targetNamespace="urn:ietf:params:xml:ns:clue-info-ext" + xmlns:tns="urn:ietf:params:xml:ns:clue-info-ext" + xmlns:clue-ext="urn:ietf:params:xml:ns:clue-info-ext" + xmlns:xs="http://www.w3.org/2001/XMLSchema" + xmlns="urn:ietf:params:xml:ns:clue-info-ext" + xmlns:xcard="urn:ietf:params:xml:ns:vcard-4.0" + xmlns:info="urn:ietf:params:xml:ns:clue-info" + elementFormDefault="qualified" + attributeFormDefault="unqualified"> + + <!-- Import xCard XML schema --> + <xs:import namespace="urn:ietf:params:xml:ns:vcard-4.0" + schemaLocation= + "https://www.iana.org/assignments/xml-registry/schema/ + vcard-4.0.xsd"/> + + <!-- Import CLUE XML schema --> + <xs:import namespace="urn:ietf:params:xml:ns:clue-info" + schemaLocation="clue-data-model-schema.xsd"/> + + <!-- ELEMENT DEFINITIONS --> + <xs:element name="newAudioFeature" type="xs:string"/> + <xs:element name="otherMediaCaptureTypeFeature" type="xs:string"/> + + </xs:schema> + + <?xml version="1.0" encoding="UTF-8" standalone="yes"?> + <clueInfo xmlns="urn:ietf:params:xml:ns:clue-info" + xmlns:ns2="urn:ietf:params:xml:ns:vcard-4.0" + xmlns:ns3="urn:ietf:params:xml:ns:clue-info-ext" + clueInfoID="NapoliRoom"> + <mediaCaptures> + <mediaCapture + xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" + xsi:type="audioCaptureType" + captureID="AC0" + mediaType="audio"> + <captureSceneIDREF>CS1</captureSceneIDREF> + <nonSpatiallyDefinable>true</nonSpatiallyDefinable> + <individual>true</individual> + <encGroupIDREF>EG1</encGroupIDREF> + <ns3:newAudioFeature>newAudioFeatureValue + </ns3:newAudioFeature> + </mediaCapture> + <mediaCapture + xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" + xsi:type="otherCaptureType" + captureID="OMC0" + mediaType="other media type"> + <captureSceneIDREF>CS1</captureSceneIDREF> + <nonSpatiallyDefinable>true</nonSpatiallyDefinable> + <encGroupIDREF>EG1</encGroupIDREF> + <ns3:otherMediaCaptureTypeFeature>OtherValue + </ns3:otherMediaCaptureTypeFeature> + </mediaCapture> + </mediaCaptures> + <encodingGroups> + <encodingGroup encodingGroupID="EG1"> + <maxGroupBandwidth>300000</maxGroupBandwidth> + <encodingIDList> + <encodingID>ENC4</encodingID> + <encodingID>ENC5</encodingID> + </encodingIDList> + </encodingGroup> + </encodingGroups> + <captureScenes> + <captureScene scale="unknown" sceneID="CS1"/> + </captureScenes> + </clueInfo> + +25. Security Considerations + + This document defines, through an XML schema, a data model for + telepresence scenarios. The modeled information is identified in the + CLUE framework as necessary in order to enable a full-fledged media + stream negotiation and rendering. Indeed, the XML elements herein + defined are used within CLUE protocol messages to describe both the + media streams representing the Media Provider's telepresence offer + and the desired selection requested by the Media Consumer. Security + concerns described in [RFC8845], Section 15 apply to this document. + + Data model information carried within CLUE messages SHOULD be + accessed only by authenticated endpoints. Indeed, authenticated + access is strongly advisable, especially if you convey information + about individuals (<personalInfo>) and/or scenes + (<sceneInformation>). There might be more exceptions, depending on + the level of criticality that is associated with the setup and + configuration of a specific session. In principle, one might even + decide that no protection at all is needed for a particular session; + here is why authentication has not been identified as a mandatory + requirement. + + Going deeper into details, some information published by the Media + Provider might reveal sensitive data about who and what is + represented in the transmitted streams. The vCard included in the + <personInfo> elements (Section 21.1) mandatorily contains the + identity of the represented person. Optionally, vCards can also + carry the person's contact addresses, together with their photo and + other personal data. Similar privacy-critical information can be + conveyed by means of <sceneInformation> elements (Section 16.1) + describing the capture scenes. The <description> elements + (Section 11.13) also can specify details about the content of media + captures, capture scenes, and scene views that should be protected. + + Integrity attacks to the data model information encapsulated in CLUE + messages can invalidate the success of the telepresence session's + setup by misleading the Media Consumer's and Media Provider's + interpretation of the offered and desired media streams. + + The assurance of the authenticated access and of the integrity of the + data model information is up to the involved transport mechanisms, + namely the CLUE protocol [RFC8847] and the CLUE data channel + [RFC8850]. + + XML parsers need to be robust with respect to malformed documents. + Reading malformed documents from unknown or untrusted sources could + result in an attacker gaining privileges of the user running the XML + parser. In an extreme situation, the entire machine could be + compromised. + +26. IANA Considerations + + This document registers a new XML namespace, a new XML schema, the + media type for the schema, and four new registries associated, + respectively, with acceptable <view>, <presentation>, + <sensitivityPattern>, and <personType> values. + +26.1. XML Namespace Registration + + URI: urn:ietf:params:xml:ns:clue-info + + Registrant Contact: IETF CLUE Working Group <clue@ietf.org>, Roberta + Presta <roberta.presta@unina.it> + + XML: + + <CODE BEGINS> + <?xml version="1.0"?> + <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML Basic 1.0//EN" + "http://www.w3.org/TR/xhtml-basic/xhtml-basic10.dtd"> + <html xmlns="http://www.w3.org/1999/xhtml"> + <head> + <meta http-equiv="content-type" + content="text/html;charset=iso-8859-1"/> + <title>CLUE Data Model Namespace</title> + </head> + <body> + <h1>Namespace for CLUE Data Model</h1> + <h2>urn:ietf:params:xml:ns:clue-info</h2> + <p>See + <a href="https://www.rfc-editor.org/rfc/rfc8846.txt">RFC 8846</a>. + </p> + </body> + </html> + <CODE ENDS> + +26.2. XML Schema Registration + + This section registers an XML schema per the guidelines in [RFC3688]. + + URI: urn:ietf:params:xml:schema:clue-info + + Registrant Contact: CLUE Working Group (clue@ietf.org), Roberta + Presta (roberta.presta@unina.it). + + Schema: The XML for this schema can be found in its entirety in + Section 4 of this document. + +26.3. Media Type Registration for "application/clue_info+xml" + + This section registers the "application/clue_info+xml" media type. + + To: ietf-types@iana.org + + Subject: Registration of media type application/clue_info+xml + + Type name: application + + Subtype name: clue_info+xml + + Required parameters: (none) + + Optional parameters: charset Same as the charset parameter of + "application/xml" as specified in [RFC7303], Section 3.2. + + Encoding considerations: Same as the encoding considerations of + "application/xml" as specified in [RFC7303], Section 3.2. + + Security considerations: This content type is designed to carry data + related to telepresence information. Some of the data could be + considered private. This media type does not provide any + protection and thus other mechanisms such as those described in + Section 25 are required to protect the data. This media type does + not contain executable content. + + Interoperability considerations: None. + + Published specification: RFC 8846 + + Applications that use this media type: CLUE-capable telepresence + systems. + + Additional Information: + + Magic Number(s): none + File extension(s): .clue + Macintosh File Type Code(s): TEXT + + Person & email address to contact for further information: Roberta + Presta (roberta.presta@unina.it). + + Intended usage: LIMITED USE + + Author/Change controller: The IETF + + Other information: This media type is a specialization of + "application/xml" [RFC7303], and many of the considerations + described there also apply to "application/clue_info+xml". + +26.4. Registry for Acceptable <view> Values + + IANA has created a registry of acceptable values for the <view> tag + as defined in Section 11.18. The initial values for this registry + are "room", "table", "lectern", "individual", and "audience". + + New values are assigned by Expert Review per [RFC8126]. This + reviewer will ensure that the requested registry entry conforms to + the prescribed formatting. + +26.5. Registry for Acceptable <presentation> Values + + IANA has created a registry of acceptable values for the + <presentation> tag as defined in Section 11.19. The initial values + for this registry are "slides" and "images". + + New values are assigned by Expert Review per [RFC8126]. This + reviewer will ensure that the requested registry entry conforms to + the prescribed formatting. + +26.6. Registry for Acceptable <sensitivityPattern> Values + + IANA has created a registry of acceptable values for the + <sensitivityPattern> tag as defined in Section 12.1. The initial + values for this registry are "uni", "shotgun", "omni", "figure8", + "cardioid", and "hyper-cardioid". + + New values are assigned by Expert Review per [RFC8126]. This + reviewer will ensure that the requested registry entry conforms to + the prescribed formatting. + +26.7. Registry for Acceptable <personType> Values + + IANA has created a registry of acceptable values for the <personType> + tag as defined in Section 21.1.3. The initial values for this + registry are "presenter", "timekeeper", "attendee", "minute taker", + "translator", "chairman", "vice-chairman", and "observer". + + New values are assigned by Expert Review per [RFC8126]. This + reviewer will ensure that the requested registry entry conforms to + the prescribed formatting. + +27. Sample XML File + + The following XML document represents a schema-compliant example of a + CLUE telepresence scenario. Taking inspiration from the examples + described in the framework specification [RFC8845], the XML + representation of an endpoint-style Media Provider's ADVERTISEMENT is + provided. + + There are three cameras, where the central one is also capable of + capturing a zoomed-out view of the overall telepresence room. + Besides the three video captures coming from the cameras, the Media + Provider makes available a further multicontent capture of the + loudest segment of the room, obtained by switching the video source + across the three cameras. For the sake of simplicity, only one audio + capture is advertised for the audio of the whole room. + + The three cameras are placed in front of three participants (Alice, + Bob, and Ciccio), whose vCard and conference role details are also + provided. + + Media captures are arranged into four capture scene views: + + 1. (VC0, VC1, VC2) - left, center, and right camera video captures + + 2. (VC3) - video capture associated with loudest room segment + + 3. (VC4) - video capture zoomed-out view of all people in the room + + 4. (AC0) - main audio + + There are two encoding groups: (i) EG0, for video encodings, and (ii) + EG1, for audio encodings. + + As to the simultaneous sets, VC1 and VC4 cannot be transmitted + simultaneously since they are captured by the same device, i.e., the + central camera (VC4 is a zoomed-out view while VC1 is a focused view + of the front participant). On the other hand, VC3 and VC4 cannot be + simultaneous either, since VC3, the loudest segment of the room, + might be at a certain point in time focusing on the central part of + the room, i.e., the same as VC1. The simultaneous sets would then be + the following: + + SS1: made by VC3 and all the captures in the first capture scene + view (VC0,VC1,and VC2) + + SS2: made by VC0, VC2, and VC4 + + <?xml version="1.0" encoding="UTF-8" standalone="yes"?> + <clueInfo xmlns="urn:ietf:params:xml:ns:clue-info" + xmlns:ns2="urn:ietf:params:xml:ns:vcard-4.0" + clueInfoID="NapoliRoom"> + <mediaCaptures> + <mediaCapture + xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" + xsi:type="audioCaptureType" captureID="AC0" + mediaType="audio"> + <captureSceneIDREF>CS1</captureSceneIDREF> + <spatialInformation> + <captureOrigin> + <capturePoint> + <x>0.0</x> + <y>0.0</y> + <z>10.0</z> + </capturePoint> + <lineOfCapturePoint> + <x>0.0</x> + <y>1.0</y> + <z>10.0</z> + </lineOfCapturePoint> + </captureOrigin> + </spatialInformation> + <individual>true</individual> + <encGroupIDREF>EG1</encGroupIDREF> + <description lang="en">main audio from the room + </description> + <priority>1</priority> + <lang>it</lang> + <mobility>static</mobility> + <view>room</view> + <capturedPeople> + <personIDREF>alice</personIDREF> + <personIDREF>bob</personIDREF> + <personIDREF>ciccio</personIDREF> + </capturedPeople> + </mediaCapture> + <mediaCapture + xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" + xsi:type="videoCaptureType" captureID="VC0" + mediaType="video"> + <captureSceneIDREF>CS1</captureSceneIDREF> + <spatialInformation> + <captureOrigin> + <capturePoint> + <x>-2.0</x> + <y>0.0</y> + <z>10.0</z> + </capturePoint> + </captureOrigin> + <captureArea> + <bottomLeft> + <x>-3.0</x> + <y>20.0</y> + <z>9.0</z> + </bottomLeft> + <bottomRight> + <x>-1.0</x> + <y>20.0</y> + <z>9.0</z> + </bottomRight> + <topLeft> + <x>-3.0</x> + <y>20.0</y> + <z>11.0</z> + </topLeft> + <topRight> + <x>-1.0</x> + <y>20.0</y> + <z>11.0</z> + </topRight> + </captureArea> + </spatialInformation> + <individual>true</individual> + <encGroupIDREF>EG0</encGroupIDREF> + <description lang="en">left camera video capture + </description> + <priority>1</priority> + <lang>it</lang> + <mobility>static</mobility> + <view>individual</view> + <capturedPeople> + <personIDREF>ciccio</personIDREF> + </capturedPeople> + </mediaCapture> + <mediaCapture + xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" + xsi:type="videoCaptureType" captureID="VC1" + mediaType="video"> + <captureSceneIDREF>CS1</captureSceneIDREF> + <spatialInformation> + <captureOrigin> + <capturePoint> + <x>0.0</x> + <y>0.0</y> + <z>10.0</z> + </capturePoint> + </captureOrigin> + <captureArea> + <bottomLeft> + <x>-1.0</x> + <y>20.0</y> + <z>9.0</z> + </bottomLeft> + <bottomRight> + <x>1.0</x> + <y>20.0</y> + <z>9.0</z> + </bottomRight> + <topLeft> + <x>-1.0</x> + <y>20.0</y> + <z>11.0</z> + </topLeft> + <topRight> + <x>1.0</x> + <y>20.0</y> + <z>11.0</z> + </topRight> + </captureArea> + </spatialInformation> + <individual>true</individual> + <encGroupIDREF>EG0</encGroupIDREF> + <description lang="en">central camera video capture + </description> + <priority>1</priority> + <lang>it</lang> + <mobility>static</mobility> + <view>individual</view> + <capturedPeople> + <personIDREF>alice</personIDREF> + </capturedPeople> + </mediaCapture> + <mediaCapture + xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" + xsi:type="videoCaptureType" captureID="VC2" + mediaType="video"> + <captureSceneIDREF>CS1</captureSceneIDREF> + <spatialInformation> + <captureOrigin> + <capturePoint> + <x>2.0</x> + <y>0.0</y> + <z>10.0</z> + </capturePoint> + </captureOrigin> + <captureArea> + <bottomLeft> + <x>1.0</x> + <y>20.0</y> + <z>9.0</z> + </bottomLeft> + <bottomRight> + <x>3.0</x> + <y>20.0</y> + <z>9.0</z> + </bottomRight> + <topLeft> + <x>1.0</x> + <y>20.0</y> + <z>11.0</z> + </topLeft> + <topRight> + <x>3.0</x> + <y>20.0</y> + <z>11.0</z> + </topRight> + </captureArea> + </spatialInformation> + <individual>true</individual> + <encGroupIDREF>EG0</encGroupIDREF> + <description lang="en">right camera video capture + </description> + <priority>1</priority> + <lang>it</lang> + <mobility>static</mobility> + <view>individual</view> + <capturedPeople> + <personIDREF>bob</personIDREF> + </capturedPeople> + </mediaCapture> + <mediaCapture + xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" + xsi:type="videoCaptureType" captureID="VC3" + mediaType="video"> + <captureSceneIDREF>CS1</captureSceneIDREF> + <spatialInformation> + <captureArea> + <bottomLeft> + <x>-3.0</x> + <y>20.0</y> + <z>9.0</z> + </bottomLeft> + <bottomRight> + <x>3.0</x> + <y>20.0</y> + <z>9.0</z> + </bottomRight> + <topLeft> + <x>-3.0</x> + <y>20.0</y> + <z>11.0</z> + </topLeft> + <topRight> + <x>3.0</x> + <y>20.0</y> + <z>11.0</z> + </topRight> + </captureArea> + </spatialInformation> + <content> + <sceneViewIDREF>SE1</sceneViewIDREF> + </content> + <policy>SoundLevel:0</policy> + <encGroupIDREF>EG0</encGroupIDREF> + <description lang="en">loudest room segment</description> + <priority>2</priority> + <lang>it</lang> + <mobility>static</mobility> + <view>individual</view> + </mediaCapture> + <mediaCapture + xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" + xsi:type="videoCaptureType" captureID="VC4" + mediaType="video"> + <captureSceneIDREF>CS1</captureSceneIDREF> + <spatialInformation> + <captureOrigin> + <capturePoint> + <x>0.0</x> + <y>0.0</y> + <z>10.0</z> + </capturePoint> + </captureOrigin> + <captureArea> + <bottomLeft> + <x>-3.0</x> + <y>20.0</y> + <z>7.0</z> + </bottomLeft> + <bottomRight> + <x>3.0</x> + <y>20.0</y> + <z>7.0</z> + </bottomRight> + <topLeft> + <x>-3.0</x> + <y>20.0</y> + <z>13.0</z> + </topLeft> + <topRight> + <x>3.0</x> + <y>20.0</y> + <z>13.0</z> + </topRight> + </captureArea> + </spatialInformation> + <individual>true</individual> + <encGroupIDREF>EG0</encGroupIDREF> + <description lang="en">zoomed-out view of all people + in the room</description> + <priority>2</priority> + <lang>it</lang> + <mobility>static</mobility> + <view>room</view> + <capturedPeople> + <personIDREF>alice</personIDREF> + <personIDREF>bob</personIDREF> + <personIDREF>ciccio</personIDREF> + </capturedPeople> + </mediaCapture> + </mediaCaptures> + <encodingGroups> + <encodingGroup encodingGroupID="EG0"> + <maxGroupBandwidth>600000</maxGroupBandwidth> + <encodingIDList> + <encodingID>ENC1</encodingID> + <encodingID>ENC2</encodingID> + <encodingID>ENC3</encodingID> + </encodingIDList> + </encodingGroup> + <encodingGroup encodingGroupID="EG1"> + <maxGroupBandwidth>300000</maxGroupBandwidth> + <encodingIDList> + <encodingID>ENC4</encodingID> + <encodingID>ENC5</encodingID> + </encodingIDList> + </encodingGroup> + </encodingGroups> + <captureScenes> + <captureScene scale="unknown" sceneID="CS1"> + <sceneViews> + <sceneView sceneViewID="SE1"> + <mediaCaptureIDs> + <mediaCaptureIDREF>VC0</mediaCaptureIDREF> + <mediaCaptureIDREF>VC1</mediaCaptureIDREF> + <mediaCaptureIDREF>VC2</mediaCaptureIDREF> + </mediaCaptureIDs> + </sceneView> + <sceneView sceneViewID="SE2"> + <mediaCaptureIDs> + <mediaCaptureIDREF>VC3</mediaCaptureIDREF> + </mediaCaptureIDs> + </sceneView> + <sceneView sceneViewID="SE3"> + <mediaCaptureIDs> + <mediaCaptureIDREF>VC4</mediaCaptureIDREF> + </mediaCaptureIDs> + </sceneView> + <sceneView sceneViewID="SE4"> + <mediaCaptureIDs> + <mediaCaptureIDREF>AC0</mediaCaptureIDREF> + </mediaCaptureIDs> + </sceneView> + </sceneViews> + </captureScene> + </captureScenes> + <simultaneousSets> + <simultaneousSet setID="SS1"> + <mediaCaptureIDREF>VC3</mediaCaptureIDREF> + <sceneViewIDREF>SE1</sceneViewIDREF> + </simultaneousSet> + <simultaneousSet setID="SS2"> + <mediaCaptureIDREF>VC0</mediaCaptureIDREF> + <mediaCaptureIDREF>VC2</mediaCaptureIDREF> + <mediaCaptureIDREF>VC4</mediaCaptureIDREF> + </simultaneousSet> + </simultaneousSets> + <people> + <person personID="bob"> + <personInfo> + <ns2:fn> + <ns2:text>Bob</ns2:text> + </ns2:fn> + </personInfo> + <personType>minute taker</personType> + </person> + <person personID="alice"> + <personInfo> + <ns2:fn> + <ns2:text>Alice</ns2:text> + </ns2:fn> + </personInfo> + <personType>presenter</personType> + </person> + <person personID="ciccio"> + <personInfo> + <ns2:fn> + <ns2:text>Ciccio</ns2:text> + </ns2:fn> + </personInfo> + <personType>chairman</personType> + <personType>timekeeper</personType> + </person> + </people> + </clueInfo> + +28. MCC Example + + Enhancing the scenario presented in the previous example, the Media + Provider is able to advertise a composed capture VC7 made by a big + picture representing the current speaker (VC3) and two picture-in- + picture boxes representing the previous speakers (the previous one, + VC5, and the oldest one, VC6). The provider does not want to + instantiate and send VC5 and VC6, so it does not associate any + encoding group with them. Their XML representations are provided for + enabling the description of VC7. + + A possible description for that scenario could be the following: + + <?xml version="1.0" encoding="UTF-8" standalone="yes"?> + <clueInfo xmlns="urn:ietf:params:xml:ns:clue-info" + xmlns:ns2="urn:ietf:params:xml:ns:vcard-4.0" clueInfoID="NapoliRoom"> + <mediaCaptures> + <mediaCapture + xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" + xsi:type="audioCaptureType" captureID="AC0" + mediaType="audio"> + <captureSceneIDREF>CS1</captureSceneIDREF> + <spatialInformation> + <captureOrigin> + <capturePoint> + <x>0.0</x> + <y>0.0</y> + <z>10.0</z> + </capturePoint> + <lineOfCapturePoint> + <x>0.0</x> + <y>1.0</y> + <z>10.0</z> + </lineOfCapturePoint> + </captureOrigin> + </spatialInformation> + <individual>true</individual> + <encGroupIDREF>EG1</encGroupIDREF> + <description lang="en">main audio from the room + </description> + <priority>1</priority> + <lang>it</lang> + <mobility>static</mobility> + <view>room</view> + <capturedPeople> + <personIDREF>alice</personIDREF> + <personIDREF>bob</personIDREF> + <personIDREF>ciccio</personIDREF> + </capturedPeople> + </mediaCapture> + <mediaCapture + xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" + xsi:type="videoCaptureType" captureID="VC0" + mediaType="video"> + <captureSceneIDREF>CS1</captureSceneIDREF> + <spatialInformation> + <captureOrigin> + <capturePoint> + <x>0.5</x> + <y>1.0</y> + <z>0.5</z> + </capturePoint> + <lineOfCapturePoint> + <x>0.5</x> + <y>0.0</y> + <z>0.5</z> + </lineOfCapturePoint> + </captureOrigin> + </spatialInformation> + <individual>true</individual> + <encGroupIDREF>EG0</encGroupIDREF> + <description lang="en">left camera video capture + </description> + <priority>1</priority> + <lang>it</lang> + <mobility>static</mobility> + <view>individual</view> + <capturedPeople> + <personIDREF>ciccio</personIDREF> + </capturedPeople> + </mediaCapture> + <mediaCapture + xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" + xsi:type="videoCaptureType" captureID="VC1" + mediaType="video"> + <captureSceneIDREF>CS1</captureSceneIDREF> + <spatialInformation> + <captureOrigin> + <capturePoint> + <x>0.0</x> + <y>0.0</y> + <z>10.0</z> + </capturePoint> + </captureOrigin> + <captureArea> + <bottomLeft> + <x>-1.0</x> + <y>20.0</y> + <z>9.0</z> + </bottomLeft> + <bottomRight> + <x>1.0</x> + <y>20.0</y> + <z>9.0</z> + </bottomRight> + <topLeft> + <x>-1.0</x> + <y>20.0</y> + <z>11.0</z> + </topLeft> + <topRight> + <x>1.0</x> + <y>20.0</y> + <z>11.0</z> + </topRight> + </captureArea> + </spatialInformation> + <individual>true</individual> + <encGroupIDREF>EG0</encGroupIDREF> + <description lang="en">central camera video capture + </description> + <priority>1</priority> + <lang>it</lang> + <mobility>static</mobility> + <view>individual</view> + <capturedPeople> + <personIDREF>alice</personIDREF> + </capturedPeople> + </mediaCapture> + <mediaCapture + xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" + xsi:type="videoCaptureType" captureID="VC2" + mediaType="video"> + <captureSceneIDREF>CS1</captureSceneIDREF> + <spatialInformation> + <captureOrigin> + <capturePoint> + <x>2.0</x> + <y>0.0</y> + <z>10.0</z> + </capturePoint> + </captureOrigin> + <captureArea> + <bottomLeft> + <x>1.0</x> + <y>20.0</y> + <z>9.0</z> + </bottomLeft> + <bottomRight> + <x>3.0</x> + <y>20.0</y> + <z>9.0</z> + </bottomRight> + <topLeft> + <x>1.0</x> + <y>20.0</y> + <z>11.0</z> + </topLeft> + <topRight> + <x>3.0</x> + <y>20.0</y> + <z>11.0</z> + </topRight> + </captureArea> + </spatialInformation> + <individual>true</individual> + <encGroupIDREF>EG0</encGroupIDREF> + <description lang="en">right camera video capture + </description> + <priority>1</priority> + <lang>it</lang> + <mobility>static</mobility> + <view>individual</view> + <capturedPeople> + <personIDREF>bob</personIDREF> + </capturedPeople> + </mediaCapture> + <mediaCapture + xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" + xsi:type="videoCaptureType" captureID="VC3" + mediaType="video"> + <captureSceneIDREF>CS1</captureSceneIDREF> + <spatialInformation> + <captureArea> + <bottomLeft> + <x>-3.0</x> + <y>20.0</y> + <z>9.0</z> + </bottomLeft> + <bottomRight> + <x>3.0</x> + <y>20.0</y> + <z>9.0</z> + </bottomRight> + <topLeft> + <x>-3.0</x> + <y>20.0</y> + <z>11.0</z> + </topLeft> + <topRight> + <x>3.0</x> + <y>20.0</y> + <z>11.0</z> + </topRight> + </captureArea> + </spatialInformation> + <content> + <sceneViewIDREF>SE1</sceneViewIDREF> + </content> + <policy>SoundLevel:0</policy> + <encGroupIDREF>EG0</encGroupIDREF> + <description lang="en">loudest room segment</description> + <priority>2</priority> + <lang>it</lang> + <mobility>static</mobility> + <view>individual</view> + </mediaCapture> + <mediaCapture + xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" + xsi:type="videoCaptureType" captureID="VC4" + mediaType="video"> + <captureSceneIDREF>CS1</captureSceneIDREF> + <spatialInformation> + <captureOrigin> + <capturePoint> + <x>0.0</x> + <y>0.0</y> + <z>10.0</z> + </capturePoint> + </captureOrigin> + <captureArea> + <bottomLeft> + <x>-3.0</x> + <y>20.0</y> + <z>7.0</z> + </bottomLeft> + <bottomRight> + <x>3.0</x> + <y>20.0</y> + <z>7.0</z> + </bottomRight> + <topLeft> + <x>-3.0</x> + <y>20.0</y> + <z>13.0</z> + </topLeft> + <topRight> + <x>3.0</x> + <y>20.0</y> + <z>13.0</z> + </topRight> + </captureArea> + </spatialInformation> + <individual>true</individual> + <encGroupIDREF>EG0</encGroupIDREF> + <description lang="en"> + zoomed-out view of all people in the room + </description> + <priority>2</priority> + <lang>it</lang> + <mobility>static</mobility> + <view>room</view> + <capturedPeople> + <personIDREF>alice</personIDREF> + <personIDREF>bob</personIDREF> + <personIDREF>ciccio</personIDREF> + </capturedPeople> + </mediaCapture> + <mediaCapture + xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" + xsi:type="videoCaptureType" captureID="VC5" + mediaType="video"> + <captureSceneIDREF>CS1</captureSceneIDREF> + <spatialInformation> + <captureArea> + <bottomLeft> + <x>-3.0</x> + <y>20.0</y> + <z>9.0</z> + </bottomLeft> + <bottomRight> + <x>3.0</x> + <y>20.0</y> + <z>9.0</z> + </bottomRight> + <topLeft> + <x>-3.0</x> + <y>20.0</y> + <z>11.0</z> + </topLeft> + <topRight> + <x>3.0</x> + <y>20.0</y> + <z>11.0</z> + </topRight> + </captureArea> + </spatialInformation> + <content> + <sceneViewIDREF>SE1</sceneViewIDREF> + </content> + <policy>SoundLevel:1</policy> + <description lang="en">previous loudest room segment + per the most recent iteration of the sound level + detection algorithm + </description> + <lang>it</lang> + <mobility>static</mobility> + <view>individual</view> + </mediaCapture> + <mediaCapture + xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" + xsi:type="videoCaptureType" captureID="VC6" + mediaType="video"> + <captureSceneIDREF>CS1</captureSceneIDREF> + <spatialInformation> + <captureArea> + <bottomLeft> + <x>-3.0</x> + <y>20.0</y> + <z>9.0</z> + </bottomLeft> + <bottomRight> + <x>3.0</x> + <y>20.0</y> + <z>9.0</z> + </bottomRight> + <topLeft> + <x>-3.0</x> + <y>20.0</y> + <z>11.0</z> + </topLeft> + <topRight> + <x>3.0</x> + <y>20.0</y> + <z>11.0</z> + </topRight> + </captureArea> + </spatialInformation> + <content> + <sceneViewIDREF>SE1</sceneViewIDREF> + </content> + <policy>SoundLevel:2</policy> + <description lang="en">previous loudest room segment + per the second most recent iteration of the sound + level detection algorithm + </description> + <lang>it</lang> + <mobility>static</mobility> + <view>individual</view> + </mediaCapture> + <mediaCapture + xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" + xsi:type="videoCaptureType" captureID="VC7" + mediaType="video"> + <captureSceneIDREF>CS1</captureSceneIDREF> + <spatialInformation> + <captureArea> + <bottomLeft> + <x>-3.0</x> + <y>20.0</y> + <z>9.0</z> + </bottomLeft> + <bottomRight> + <x>3.0</x> + <y>20.0</y> + <z>9.0</z> + </bottomRight> + <topLeft> + <x>-3.0</x> + <y>20.0</y> + <z>11.0</z> + </topLeft> + <topRight> + <x>3.0</x> + <y>20.0</y> + <z>11.0</z> + </topRight> + </captureArea> + </spatialInformation> + <content> + <mediaCaptureIDREF>VC3</mediaCaptureIDREF> + <mediaCaptureIDREF>VC5</mediaCaptureIDREF> + <mediaCaptureIDREF>VC6</mediaCaptureIDREF> + </content> + <maxCaptures exactNumber="true">3</maxCaptures> + <encGroupIDREF>EG0</encGroupIDREF> + <description lang="en">big picture of the current + speaker + pips about previous speakers</description> + <priority>3</priority> + <lang>it</lang> + <mobility>static</mobility> + <view>individual</view> + </mediaCapture> + </mediaCaptures> + <encodingGroups> + <encodingGroup encodingGroupID="EG0"> + <maxGroupBandwidth>600000</maxGroupBandwidth> + <encodingIDList> + <encodingID>ENC1</encodingID> + <encodingID>ENC2</encodingID> + <encodingID>ENC3</encodingID> + </encodingIDList> + </encodingGroup> + <encodingGroup encodingGroupID="EG1"> + <maxGroupBandwidth>300000</maxGroupBandwidth> + <encodingIDList> + <encodingID>ENC4</encodingID> + <encodingID>ENC5</encodingID> + </encodingIDList> + </encodingGroup> + </encodingGroups> + <captureScenes> + <captureScene scale="unknown" sceneID="CS1"> + <sceneViews> + <sceneView sceneViewID="SE1"> + <description lang="en">participants' individual + videos</description> + <mediaCaptureIDs> + <mediaCaptureIDREF>VC0</mediaCaptureIDREF> + <mediaCaptureIDREF>VC1</mediaCaptureIDREF> + <mediaCaptureIDREF>VC2</mediaCaptureIDREF> + </mediaCaptureIDs> + </sceneView> + <sceneView sceneViewID="SE2"> + <description lang="en">loudest segment of the + room</description> + <mediaCaptureIDs> + <mediaCaptureIDREF>VC3</mediaCaptureIDREF> + </mediaCaptureIDs> + </sceneView> + <sceneView sceneViewID="SE5"> + <description lang="en">loudest segment of the + room + pips</description> + <mediaCaptureIDs> + <mediaCaptureIDREF>VC7</mediaCaptureIDREF> + </mediaCaptureIDs> + </sceneView> + <sceneView sceneViewID="SE4"> + <description lang="en">room audio</description> + <mediaCaptureIDs> + <mediaCaptureIDREF>AC0</mediaCaptureIDREF> + </mediaCaptureIDs> + </sceneView> + <sceneView sceneViewID="SE3"> + <description lang="en">room video</description> + <mediaCaptureIDs> + <mediaCaptureIDREF>VC4</mediaCaptureIDREF> + </mediaCaptureIDs> + </sceneView> + </sceneViews> + </captureScene> + </captureScenes> + <simultaneousSets> + <simultaneousSet setID="SS1"> + <mediaCaptureIDREF>VC3</mediaCaptureIDREF> + <mediaCaptureIDREF>VC7</mediaCaptureIDREF> + <sceneViewIDREF>SE1</sceneViewIDREF> + </simultaneousSet> + <simultaneousSet setID="SS2"> + <mediaCaptureIDREF>VC0</mediaCaptureIDREF> + <mediaCaptureIDREF>VC2</mediaCaptureIDREF> + <mediaCaptureIDREF>VC4</mediaCaptureIDREF> + </simultaneousSet> + </simultaneousSets> + <people> + <person personID="bob"> + <personInfo> + <ns2:fn> + <ns2:text>Bob</ns2:text> + </ns2:fn> + </personInfo> + <personType>minute taker</personType> + </person> + <person personID="alice"> + <personInfo> + <ns2:fn> + <ns2:text>Alice</ns2:text> + </ns2:fn> + </personInfo> + <personType>presenter</personType> + </person> + <person personID="ciccio"> + <personInfo> + <ns2:fn> + <ns2:text>Ciccio</ns2:text> + </ns2:fn> + </personInfo> + <personType>chairman</personType> + <personType>timekeeper</personType> + </person> + </people> + </clueInfo> + +29. References + +29.1. Normative References + + [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate + Requirement Levels", BCP 14, RFC 2119, + DOI 10.17487/RFC2119, March 1997, + <https://www.rfc-editor.org/info/rfc2119>. + + [RFC5646] Phillips, A., Ed. and M. Davis, Ed., "Tags for Identifying + Languages", BCP 47, RFC 5646, DOI 10.17487/RFC5646, + September 2009, <https://www.rfc-editor.org/info/rfc5646>. + + [RFC6351] Perreault, S., "xCard: vCard XML Representation", + RFC 6351, DOI 10.17487/RFC6351, August 2011, + <https://www.rfc-editor.org/info/rfc6351>. + + [RFC7303] Thompson, H. and C. Lilley, "XML Media Types", RFC 7303, + DOI 10.17487/RFC7303, July 2014, + <https://www.rfc-editor.org/info/rfc7303>. + + [RFC7852] Gellens, R., Rosen, B., Tschofenig, H., Marshall, R., and + J. Winterbottom, "Additional Data Related to an Emergency + Call", RFC 7852, DOI 10.17487/RFC7852, July 2016, + <https://www.rfc-editor.org/info/rfc7852>. + + [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for + Writing an IANA Considerations Section in RFCs", BCP 26, + RFC 8126, DOI 10.17487/RFC8126, June 2017, + <https://www.rfc-editor.org/info/rfc8126>. + + [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC + 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, + May 2017, <https://www.rfc-editor.org/info/rfc8174>. + + [RFC8845] Duckworth, M., Ed., Pepperell, A., and S. Wenger, + "Framework for Telepresence Multi-Streams", RFC 8845, + DOI 10.17487/RFC8845, January 2021, + <https://www.rfc-editor.org/info/rfc8845>. + + [RFC8847] Presta, R. and S P. Romano, "Protocol for Controlling + Multiple Streams for Telepresence (CLUE)", RFC 8847, + DOI 10.17487/RFC8847, January 2021, + <https://www.rfc-editor.org/info/rfc8847>. + + [RFC8850] Holmberg, C., "Controlling Multiple Streams for + Telepresence (CLUE) Protocol Data Channel", RFC 8850, + DOI 10.17487/RFC8850, January 2021, + <https://www.rfc-editor.org/info/rfc8850>. + +29.2. Informative References + + [RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V. + Jacobson, "RTP: A Transport Protocol for Real-Time + Applications", STD 64, RFC 3550, DOI 10.17487/RFC3550, + July 2003, <https://www.rfc-editor.org/info/rfc3550>. + + [RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, + DOI 10.17487/RFC3688, January 2004, + <https://www.rfc-editor.org/info/rfc3688>. + + [RFC4353] Rosenberg, J., "A Framework for Conferencing with the + Session Initiation Protocol (SIP)", RFC 4353, + DOI 10.17487/RFC4353, February 2006, + <https://www.rfc-editor.org/info/rfc4353>. + + [RFC6838] Freed, N., Klensin, J., and T. Hansen, "Media Type + Specifications and Registration Procedures", BCP 13, + RFC 6838, DOI 10.17487/RFC6838, January 2013, + <https://www.rfc-editor.org/info/rfc6838>. + + [RFC7667] Westerlund, M. and S. Wenger, "RTP Topologies", RFC 7667, + DOI 10.17487/RFC7667, November 2015, + <https://www.rfc-editor.org/info/rfc7667>. + +Acknowledgements + + The authors thank all the CLUE contributors for their valuable + feedback and support. Thanks also to Alissa Cooper, whose AD review + helped us improve the quality of the document. + +Authors' Addresses + + Roberta Presta + University of Napoli + Via Claudio 21 + 80125 Napoli + Italy + + Email: roberta.presta@unina.it + + + Simon Pietro Romano + University of Napoli + Via Claudio 21 + 80125 Napoli + Italy + + Email: spromano@unina.it |