MMUSIC J-P. Luoma Internet-Draft Nokia Expires: June 18, 2004 J. Peltotalo S. Peltotalo Tampere University of Technology December 19, 2003 A Metadata Framework for Internet Media Guides: Baseline Data Model draft-luoma-mmusic-img-metadata-03 Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http:// www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on June 18, 2004. Copyright Notice Copyright (C) The Internet Society (2003). All Rights Reserved. Abstract This document defines the base metadata format for Internet Media Guides (IMGs), applicable to a wide variety of Internet hosts and communication links. IMG metadata describes files, resources and multimedia programs available for streaming or downloading via multicast or unicast. An IMG metadata model and semantics of the IMG media metadata entities are defined. The aim is to reuse existing metadata standards for the IMG metadata format where possible. Luoma, et al. Expires June 18, 2004 [Page 1] Internet-Draft IMG Metadata December 2003 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Conventions Used in This Document . . . . . . . . . . . . . 4 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . 5 4. IMG Metadata Model . . . . . . . . . . . . . . . . . . . . . 7 4.1 The Relational Part of IMG Metadata . . . . . . . . . . . . 7 4.1.1 IMG Root . . . . . . . . . . . . . . . . . . . . . . . . . . 9 4.1.2 Category . . . . . . . . . . . . . . . . . . . . . . . . . . 10 4.1.3 IP Service Portal . . . . . . . . . . . . . . . . . . . . . 10 4.1.4 IP Service Unit . . . . . . . . . . . . . . . . . . . . . . 11 4.1.5 IP Service . . . . . . . . . . . . . . . . . . . . . . . . . 11 4.1.6 IP Service Bundle . . . . . . . . . . . . . . . . . . . . . 12 4.1.7 Access Info . . . . . . . . . . . . . . . . . . . . . . . . 12 4.2 The Session Part of IMG Metadata . . . . . . . . . . . . . . 12 4.2.1 IP Session . . . . . . . . . . . . . . . . . . . . . . . . . 12 4.2.2 IP Session Component . . . . . . . . . . . . . . . . . . . . 13 4.2.3 Scheduling Info . . . . . . . . . . . . . . . . . . . . . . 14 4.2.4 Transport Channel . . . . . . . . . . . . . . . . . . . . . 14 4.3 The Content Part of IMG Metadata . . . . . . . . . . . . . . 14 4.3.1 Content . . . . . . . . . . . . . . . . . . . . . . . . . . 15 4.3.2 Content Item . . . . . . . . . . . . . . . . . . . . . . . . 15 4.3.3 Content Bundle . . . . . . . . . . . . . . . . . . . . . . . 16 4.3.4 Access Info . . . . . . . . . . . . . . . . . . . . . . . . 16 4.3.5 Scheduling Info . . . . . . . . . . . . . . . . . . . . . . 16 5. IMG Metadata Format . . . . . . . . . . . . . . . . . . . . 17 6. Security Considerations . . . . . . . . . . . . . . . . . . 18 7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 19 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 20 Normative References . . . . . . . . . . . . . . . . . . . . 21 Informative References . . . . . . . . . . . . . . . . . . . 22 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 22 Intellectual Property and Copyright Statements . . . . . . . 23 Luoma, et al. Expires June 18, 2004 [Page 2] Internet-Draft IMG Metadata December 2003 1. Introduction This document defines the Internet Media Guide (IMG) metadata model and the IMG media metadata elements. This is intended as a baseline specification of the IMG metadata format that can be supplemented by other specifications, e.g. for application-specific extensions. The scope and background of the work on Internet Media Guides have been described in the IMG requirements [2] and IMG framework [3] specifications. The purpose of the IMG metadata is to provide machine- and human-readable information describing the files, resources and multimedia programs available for streaming or downloading via multicast or unicast. The IMG metadata format will be used in the IMG framework [3] as a payload format for IMG transport protocols, such as MUPPET [8]. The IMG media metadata (or references to it) is encapsulated into, or associated with, an IMG transfer envelope [9] before actual transport. The aim is to reuse existing metadata standards for the IMG metadata format where possible. Luoma, et al. Expires June 18, 2004 [Page 3] Internet-Draft IMG Metadata December 2003 2. Conventions Used in This Document The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [1]. Luoma, et al. Expires June 18, 2004 [Page 4] Internet-Draft IMG Metadata December 2003 3. Terminology Internet Media Guide (IMG) An IMG is a generic term to describe the formation, delivery and use of IMG metadata. The definition of the IMG is intentionally left imprecise. IMG Element The smallest atomic element of IMG metadata that can be transmitted separately and referenced individually from other IMG elements. IMG Media Metadata Includes the relational part, session part and content part of IMG metadata. Does not include the metadata relating to IMG transport, e.g. the fields of the IMG transfer envelope [9]. IMG Metadata A set of metadata consisting of one or more IMG elements. IMG metadata describes the features of multimedia content used to enable selection of and access to media sessions containing content. For example, metadata may consist of the URI, title, airtime, bandwidth needed, file size, text summary, genre and access restrictions. IMG Metadata Model Defines the information content, semantics and relations of the different IMG metadata entities. IMG Receiver A logical entity that receives media guides from an IMG sender, analogous to a client. IMG Sender A logical entity that delivers IMG metadata to one or more IMG receivers, analogous to a server. A sender shall provide bandwidth control or congestion control schemes on the output. A sender can additionally be a receiver - see IMG transceiver. IMG Transceiver Luoma, et al. Expires June 18, 2004 [Page 5] Internet-Draft IMG Metadata December 2003 A combination of an IMG receiver and sender. IMG Transport Protocol A protocol that transports IMG metadata from IMG sender to IMG receiver(s). Luoma, et al. Expires June 18, 2004 [Page 6] Internet-Draft IMG Metadata December 2003 4. IMG Metadata Model The media metadata in an Internet Media Guide is structured in three parts: a relatively static part known as the 'relational part' and the more dynamic parts known as the 'session part' and 'content part'. This chapter describes the metadata entities and their relations in the three parts of IMG metadata. This chapter describes a baseline metadata model for Internet Media Guides that includes metadata entities common for most IMG usage scenarios. It should be possible to extend the IMG metadata format, e.g. with application-specific parts, but such extensions are outside the scope of this document. Note, some metadata fields are marked 'optional' to indicate that it is optional whether to use these fields in the respective metadata. However, IMG receivers MUST be capable of parsing both 'mandatory' and 'optional' fields. 4.1 The Relational Part of IMG Metadata The relation part of the IMG metadata is used to relate the various parts of the metadata. This includes IP service portals based on the type of content, and to organize IP services into IP service portals. The metadata in the relational part is intended to be browsed by end-users and by end-user applications, allowing them to decide on what content to receive. For example, an IMG could be rendered as a simple hierarchy as shown in Figure 1. Luoma, et al. Expires June 18, 2004 [Page 7] Internet-Draft IMG Metadata December 2003 Root | +--News Category | | | +--CNN IP Service Portal | | | | | +--World news Category | | | | | | | +--LiveUpdate IP Service | | | | | +--Business news Category | | | | | +--Sports news Category | | | +--BBC World IP Service Portal | +--Entertainment Category | +--Music Category | +--Videos Category Figure 1: Example of an IMG service hierarchy The relations between the metadata elements that constitute an IMG hierarchy are shown in Figure 2. Note that the cardinalities between metadata elements in this and the other entity relationship diagrams are denoted as follows: o 0..1: Zero or one occurrences. o 1: Exactly one occurrence. o *: Zero or more occurrences. o 1..*: One or more occurrences. Luoma, et al. Expires June 18, 2004 [Page 8] Internet-Draft IMG Metadata December 2003 includes +---+ * | | 0..1 V | +----------+ includes +----------+ | IMG Root |---------->| Category | +----------+ 0..1 * +----------+ ^ is-a | | +-------------------+ | IP Service Portal | +-------------------+ | 1..* includes | V * includes +-------------------+ +-------------+ +----------------->| IP Service Unit |--------| Access Info | | 0..1 +-------------------+ 1 0..1 +-------------+ | ^ | | is-a | +-------------+-----------+ | | | | +-------------------+ +------------+ +----| IP Service Bundle | | IP Service | 0..1 +-------------------+ +------------+ | 1..* includes | V * +------------+ | IP Session | +------------+ Figure 2: Relational part of the IMG metadata The metadata elements of the relational part are described in the following subsections. Note that IP session belongs to the session part rather than the relational part of IMG metadata, and is only shown in Figure 2 to show the connection between the two parts - see Section 4.2.1 for definition of IP session. 4.1.1 IMG Root The IMG root is a logical entity that represents one IMG database. It is expected that both single logical receivers and single logical senders will maintain their own single IMG root (thus an IMG single database). Thus an IMG root is unique to a unique logical host. Luoma, et al. Expires June 18, 2004 [Page 9] Internet-Draft IMG Metadata December 2003 It may be desirable or a host to separate IMG roots from different senders (or senders in separately administered domains). Thus, a practical refinement is that one receiver may maintain more than one IMG root (in one or more actual databases). In this case the receiver is behaving as multiple logical receivers, possibly sharing actual processes, databases and user interfaces. The document does not impose any requirements on the relationships between the deployment of physical devices and of: logical senders; logical transceivers; and, logical receivers. IMG root is a container for the other IMG elements. The only information field in the IMG root itself is the identifier of the Internet Media Guide represented by the IMG root: o IMG ID: The unique identifier of the IMG. 4.1.2 Category The category provides a classification for content, allowing end-users to browse available content according to category or client software to automatically filter content. Each category node MAY be associated with categories of the next lower hierarchy level. Except for root-level categories, one higher-level category node MUST be associated with every category node. The following information fields are included for a category: o Category ID: The unique identifier of the category. o Name: The name of the category. o Description (optional): Short description for the category. o Parental rating (optional): Minimum recommended age to access the category - if absent it is assumed there are no restrictions. o Additional information (optional): A URL for retrieving additional information. 4.1.3 IP Service Portal An IP service portal is a collection of services offered by a single service provider or a content provider. An IP service portal MUST be associated with one content category node. The path of content category nodes from the root of service hierarchy tree to the IP service portal (e.g., 'entertainment.music.videos') defines the Luoma, et al. Expires June 18, 2004 [Page 10] Internet-Draft IMG Metadata December 2003 category of the portal. IP Service Portal inherits the field of category and also uses: o Contact details (optional): A URL to human-readable contact info. o Logo (optional): A URL to a graphical logo of the service/content provider. 4.1.4 IP Service Unit Any number of IP service units can be included in an IP service portal. IP service unit is used here as an abstract entity that is realized either as an IP service or an IP service bundle. A separate access info element may be associated either with an IP service or an IP service bundle. 4.1.5 IP Service An IP service consists of a number of IP sessions and belongs to one or more content categories. The following information fields are included: o Service ID: The unique identifier of IP service. o Name: The name of the IP service. o Description (optional): Short description of the IP service. o Genre (optional): The genre of the IP service. o Parental rating: Minimum recommended age to access the IP service (optional - if absent it is assumed there are no restrictions). o Client content path (optional): Recommended path in the receiver's file system for storing the content of this service. This would be a relative path, which also requires a (receiving) application-specific base path to identify the complete local path. o Response URL (optional): A URL that can be used by clients to provide feedback, e.g. a five-star rating for the service. o Additional information (optional): A URL for retrieving additional information. Luoma, et al. Expires June 18, 2004 [Page 11] Internet-Draft IMG Metadata December 2003 4.1.6 IP Service Bundle An IP service bundle is a set consisting of IP services or other IP service bundles. For example, an IP service offering a number of sessions carrying sports-related content might be bundled together with an IP service carrying sessions that distribute movie content. The following information fields are included: o Bundle ID: The unique identifier of the IP service bundle. o Name: The name of the IP service bundle. 4.1.7 Access Info An access info describes the requirements or preconditions that must be met in order to access a particular IP service unit or content. For example, details of pricing/billing and age limits could be part of the access info. 4.2 The Session Part of IMG Metadata The session part of IMG metadata is used to describe the scheduling, transport and any audio/video codec parameters of media streams, as well as the binding of these media streams into IP sessions (see Figure 3). Using this part of IMG metadata, client-side applications are able to receive and present media streams belonging to IP sessions. +-----------------+ +------------+ | Scheduling Info |---------------| IP Session | +-----------------+ 1 1 +------------+ | 1 consists of | V 1..* +--------------------+ delivers +----------------------+ | Transport Channel |--------->| IP Session Component | +--------------------+ 1..* 1 +----------------------+ Figure 3: Session part of the IMG metadata 4.2.1 IP Session An IP session is the collection of related media streams used for delivering IP based content to clients. A session is associated with one or more IP services, and shares the category assigned to those IP services. The lifetime of an IP session is typically much shorter Luoma, et al. Expires June 18, 2004 [Page 12] Internet-Draft IMG Metadata December 2003 than that of an IP service. The following information fields are included in this metadata element: o Session ID: The unique identifier of the IP session. o Version: Version number of the session description. o Name: The name of the IP session. o Owner (optional): The name of the owner/creator of the IP session. o Bandwidth (optional): Total bandwidth requirements of the IP session. o Encryption info (optional): Type of content encryption used and related parameters. o Authentication info (optional): Type of content authentication used and related parameters. 4.2.2 IP Session Component An IP session component refers to a single media stream that is part of an IP session, e.g. video, audio or data flow. Each media stream is delivered on one more logical transport channels. An IP session component is described using the following parameters: o Bandwidth (optional): Bandwidth requirements of the IP session component. o Addressing: The Layer 3 and Layer 4 addressing used for delivering the IP session component. o Transport: The transport protocol used. o Codec parameters (optional): The parameters of the audio/video codec needed to present the media stream. o Encryption info (optional): Type of content encryption used and related parameters. o Authentication info (optional): Type of content authentication used and related parameters. Luoma, et al. Expires June 18, 2004 [Page 13] Internet-Draft IMG Metadata December 2003 4.2.3 Scheduling Info A delivery schedule is always associated with an IP session. Both the start and the end time of an IP session are usually bounded. Either a single time period, or a repeating schedule may be specified. The following information fields are included: o Start (optional): The start time. o End (optional): The end time. o Repeat (optional): Information on the repetition pattern. o Timezone (optional): Information on any timezone adjustments taking place. 4.2.4 Transport Channel A logical transport channel in an IP network is defined here by the Layer 3 and Layer 4 protocols and addressing parameters used. It includes the following: o Source IP address: IPv4 or IPv6 address. o Destination/group IP address: IPv4 or IPv6 address. o Source port: Port number. o Destination port: Port number. o Transport protocol: Transport layer protocol(s) used, e.g. RTP/ UDP. o Additional transport parameters (optional): For example, additional Asyncronous Layered Coding (ALC) parameters. 4.3 The Content Part of IMG Metadata The content part of IMG metadata identifies and describes items of content delivered within IP sessions, and grouping of these content items into bundles of related content (see Figure 4). This part of the IMG metadata provides more details into the available content, helping end-users and client applications to decide on which IP sessions to receive. Luoma, et al. Expires June 18, 2004 [Page 14] Internet-Draft IMG Metadata December 2003 +------------+ | IP Session | +------------+ | 1..* delivers | V * includes +---------+ +-------------+ +------------------>| Content |----------| Access Info | | 1..* +---------+ 1 0..1 +-------------+ | ^ | | is-a | +---------+---------+ | | | | +----------------+ +--------------+ +-----| Content Bundle | | Content Item | 0..1 +----------------+ +--------------+ | 1 | | 0..1 +-----------------+ | Scheduling Info | +-----------------+ Figure 4: Content part of the IMG metadata The metadata elements of the content part are described in the following subsections. Note that IP session belongs to the session part rather than content part of IMG metadata, and is only shown in Figure 2 to show the connection between the two parts. See Section 4.2.1 for definition of IP session. 4.3.1 Content Any number of instances of content can be included in an IP session. Content is used here as an abstract entity that is realized either as a content item or a content bundle. 4.3.2 Content Item A content item is an atomic item of content delivered by the IP network and consumed by the end-user, such as an MP3 file or a real-time audio/video stream. The following information fields are included: o Content item ID: The unique identifier of the content item. o Name: The name of the content item. Luoma, et al. Expires June 18, 2004 [Page 15] Internet-Draft IMG Metadata December 2003 o Content location (optional): The URL or filename used for accessing the content item. o Genre (optional): The genre of the content item. o Creator (optional): The creator of the content item. o Owner (optional): The owner rights to this content item (note, the rights may be dependent on the context, e.g. copyright ownership for streaming delivery). o Description (optional): Short description of the content item. o Parental rating (optional): Minimum recommended age to access the content item. o Rating URL (optional): A URL that can be used by clients for rating the service. 4.3.3 Content Bundle A content bundle is a set of content items or other content bundles. For example, a set of PC game downloads can be defined as a content bundle. Similarly, a news broadcast that consists of the domestic, foreign and sports news as separate content items can be defined as a content bundle. The following information fields are included: o Bundle ID: The unique identifier of the content bundle. o Name: The name of the content bundle. 4.3.4 Access Info As described in Section 4.1.7. 4.3.5 Scheduling Info There may be a delivery schedule associated with an individual content item. This information content of this entity is as defined in Section 4.2.3. Luoma, et al. Expires June 18, 2004 [Page 16] Internet-Draft IMG Metadata December 2003 5. IMG Metadata Format If necessary an XML schema can be defined for some parts of the IMG metadata that cannot be implemented using existing standards. Currently, the following standards are being considered for IMG metadata: o MPEG-7 [4] (content part of IMG media metadata). o SDP [5] or SDPng [10] (session part of IMG media metadata). o XPath [6] or XPointer [7] (references to IMG metadata elements). Luoma, et al. Expires June 18, 2004 [Page 17] Internet-Draft IMG Metadata December 2003 6. Security Considerations IMG receivers should only trust IMG metadata received from a trusted source, with data integrity and authentication of the original IMG sender provided at IMG metadata level or by IMG transport protocol. IMG receivers also should not trust IMG metadata modified by an IMG transceiver, unless the IMG transceiver is trusted and the integrity and authenticity of the changes can be similarly verified. However, to operate in a typical network environment lacking infrastructure for key distribution and trust verification, IMG receivers may also be configured to accept untrusted IMG metadata. There may also be need to provide access control to the content described by the IMG or to protect the confidentiality of an individual user requesting a particular subset of an IMG. Such privacy requirements are met by the use of encryption at IMG metadata level or by IMG transport protocol. Luoma, et al. Expires June 18, 2004 [Page 18] Internet-Draft IMG Metadata December 2003 7. Contributors Rod Walsh Nokia Research Center P.O. Box 100 (Visiokatu 1) FIN-33721 Tampere Finland EMail: rod.walsh@nokia.com Toni Paila Nokia Ventures Organization P.O. Box 209 (Itamerenkatu 11-13) FIN-00181 Helsinki Finland EMail: toni.paila@nokia.com Luoma, et al. Expires June 18, 2004 [Page 19] Internet-Draft IMG Metadata December 2003 8. Acknowledgements The authors' wishes to thank Yuji Nomura, Henning Schulzrinne and Rami Lehtonen for providing comments on IMG metadata design. Luoma, et al. Expires June 18, 2004 [Page 20] Internet-Draft IMG Metadata December 2003 Normative References [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", RFC 2119, BCD 14, March 1997. [2] Nomura, Y., Walsh, R., Luoma, J-P., Ott, J. and H. Schulzrinne, "Protocol Requirements for Internet Media Guides", draft-ietf-mmusic-img-req-01 (work in progress), December 2003. [3] Nomura, Y., Walsh, R., Luoma, J-P., Asaeda, H. and H. Schulzrinne, "A Framework for the Usage of Internet Media Guides", draft-ietf-mmusic-img-framework-01 (work in progress), December 2003. [4] ISO (International Organization for Standardization), "Overview of the MPEG-7 standard", ISO Standard ISO/IEC JTC1/SC29/WG11 N4509, International Organization for Standardization, Geneva, Switzerland, December 2001. [5] Handley, M. and V. Jacobson, "SDP: Session Description Protocol", RFC 2327, April 1998. [6] Clark, J. and Steven. DeRose, "XML Path Language (XPath) Version 1.0", W3C Recommendation REC-xpath-19991116, November 1999. [7] Grosso, P., Maler, E., Marsh, J. and N. Walsh, "XPointer Framework", W3C Recommendation REC-xptr-framework-20030325, March 2003. Luoma, et al. Expires June 18, 2004 [Page 21] Internet-Draft IMG Metadata December 2003 Informative References [8] Luoma, J-P., Peltotalo, J. and S. Peltotalo, "MUPPET: Internet Media Guide Unidirectional Point-to-Multipoint Transport", draft-luoma-mmusic-img-muppet-04 (work in progress), December 2003. [9] Luoma, J-P., Peltotalo, J. and S. Peltotalo, "A Metadata Framework for Internet Media Guides: Metadata Envelope", draft-luoma-mmusic-img-metadata-envelope-00 (work in progress), December 2003. [10] Ott, J., Bormann, C. and D. Kutscher, "Session Description and Capability Negotiation", draft-ietf-mmusic-sdpng-07 (work in progress), October 2003. Authors' Addresses Juha-Pekka Luoma Nokia P.O. Box 100 (Visiokatu 1) Tampere FIN-33721 Finland EMail: juha-pekka.luoma@nokia.com Jani Peltotalo Tampere University of Technology P.O. Box 553 (Korkeakoulunkatu 1) Tampere FIN-33101 Finland EMail: jani.peltotalo@tut.fi Sami Peltotalo Tampere University of Technology P.O. Box 553 (Korkeakoulunkatu 1) Tampere FIN-33101 Finland EMail: sami.peltotalo@tut.fi Luoma, et al. Expires June 18, 2004 [Page 22] Internet-Draft IMG Metadata December 2003 Intellectual Property Statement The IETF takes no position regarding the validity or scope of any intellectual property or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; neither does it represent that it has made any effort to identify any such rights. Information on the IETF's procedures with respect to rights in standards-track and standards-related documentation can be found in BCP-11. Copies of claims of rights made available for publication and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementors or users of this specification can be obtained from the IETF Secretariat. 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Expires June 18, 2004 [Page 23] Internet-Draft IMG Metadata December 2003 HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Luoma, et al. Expires June 18, 2004 [Page 24]