1、 I n t e r n a t i o n a l T e l e c o m m u n i c a t i o n U n i o n ITU-T H.248.96 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (11/2015) SERIES H: AUDIOVISUAL AND MULTIMEDIA SYSTEMS Infrastructure of audiovisual services Communication procedures Gateway control protocol: ITU-T H.248 Stream gr
2、ouping and aggregation Recommendation ITU-T H.248.96 ITU-T H-SERIES RECOMMENDATIONS AUDIOVISUAL AND MULTIMEDIA SYSTEMS CHARACTERISTICS OF VISUAL TELEPHONE SYSTEMS H.100H.199 INFRASTRUCTURE OF AUDIOVISUAL SERVICES General H.200H.219 Transmission multiplexing and synchronization H.220H.229 Systems asp
3、ects H.230H.239 Communication procedures H.240H.259 Coding of moving video H.260H.279 Related systems aspects H.280H.299 Systems and terminal equipment for audiovisual services H.300H.349 Directory services architecture for audiovisual and multimedia services H.350H.359 Quality of service architectu
4、re for audiovisual and multimedia services H.360H.369 Telepresence H.420H.429 Supplementary services for multimedia H.450H.499 MOBILITY AND COLLABORATION PROCEDURES Overview of Mobility and Collaboration, definitions, protocols and procedures H.500H.509 Mobility for H-Series multimedia systems and s
5、ervices H.510H.519 Mobile multimedia collaboration applications and services H.520H.529 Security for mobile multimedia systems and services H.530H.539 Security for mobile multimedia collaboration applications and services H.540H.549 Mobility interworking procedures H.550H.559 Mobile multimedia colla
6、boration inter-working procedures H.560H.569 BROADBAND, TRIPLE-PLAY AND ADVANCED MULTIMEDIA SERVICES Broadband multimedia services over VDSL H.610H.619 Advanced multimedia services and applications H.620H.629 Ubiquitous sensor network applications and Internet of Things H.640H.649 IPTV MULTIMEDIA SE
7、RVICES AND APPLICATIONS FOR IPTV General aspects H.700H.719 IPTV terminal devices H.720H.729 IPTV middleware H.730H.739 IPTV application event handling H.740H.749 IPTV metadata H.750H.759 IPTV multimedia application frameworks H.760H.769 IPTV service discovery up to consumption H.770H.779 Digital Si
8、gnage H.780H.789 E-HEALTH MULTIMEDIA SERVICES AND APPLICATIONS Personal health systems H.810H.819 Interoperability compliance testing of personal health systems (HRN, PAN, LAN, TAN and WAN) H.820H.859 Multimedia e-health data exchange services H.860H.869 For further details, please refer to the list
9、 of ITU-T Recommendations. Rec. ITU-T H.248.96 (11/2015) i Recommendation ITU-T H.248.96 Gateway control protocol: ITU-T H.248 Stream grouping and aggregation Summary Recommendation ITU-T H.248.96 discusses how ITU-T H.248 Streams may be grouped according to a particular semantic and how they are ag
10、gregated or deaggregated internally in the Context for the execution of ITU-T H.248 control actions. It defines an ITU-T H.248 package that allows an explicit grouping semantic to be assigned to a group of streams. It also introduces the concept and support for a new type of ITU-T H.248 Stream, the
11、aggregation stream, the deaggregation stream and the component stream, to be used only in combination with stream grouping. The ability to group streams and to provide an explicit semantic allows the media gateway controller (MGC) to control the processing of multiple streams. The concept of aggrega
12、tion allows Signals, Events, Statistics and Topology to be applied to an aggregation stream with benefits including, for example: the ability to report cumulative Statistics rather than multiple individual Statistics or report a single Event rather multiple Events on the component streams. The conce
13、pt of deaggregation allows a better handling of multiple streams that share the same transport, for example, with regard to the different time dynamics of the transport layer and the upper layer streams. History Edition Recommendation Approval Study Group Unique ID* 1.0 ITU-T H.248.96 2015-11-29 16
14、11.1002/1000/12638 * To access the Recommendation, type the URL http:/handle.itu.int/ in the address field of your web browser, followed by the Recommendations unique ID. For example, http:/handle.itu.int/11.1002/1000/11830-en. ii Rec. ITU-T H.248.96 (11/2015) FOREWORD The International Telecommunic
15、ation Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff qu
16、estions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendati
17、ons on these topics. The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. NOTE In this Recommendation
18、, the expression “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability o
19、r applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words “shall“ or some other obligatory language such as “must“ and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance
20、 with the Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTSITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or ap
21、plicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to im
22、plement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2016 All rights reserved. No part of this publication may be reproduced, by any
23、 means whatsoever, without the prior written permission of ITU. Rec. ITU-T H.248.96 (11/2015) iii Table of Contents Page 1 Scope . 1 2 References . 1 3 Definitions 2 3.1 Terms defined elsewhere 2 3.2 Terms defined in this Recommendation . 2 4 Abbreviations and acronyms 3 5 Conventions 5 5.1 General
24、. 5 5.2 Terminology relationships related to grouping 5 5.3 Terminology relationships related to the semantic of “stream“ . 5 6 ITU-T H.248.1 defined stream grouping, aggregation and multiplexing . 6 6.1 ReserveGroup attribute . 6 6.2 Stream multiplexing using transport address information 6 7 Furth
25、er issues with existing ITU-T H.248 stream grouping mechanisms 8 7.1 Scope of Signals/Events and Statistics . 8 7.2 Scope of Topology . 8 8 Media Grouping package 8 8.1 Properties 9 8.2 Events . 10 8.3 Signals 10 8.4 Statistics 10 8.5 Error codes 10 8.6 Procedures 11 Annex A Codepoints for parameter
26、 Semantics of ITU-T H.248 property Group Semantics 30 A.1 Introduction and purpose 30 A.2 IETF defined codepoints 30 A.3 ITU-T defined codepoints 30 Appendix I Cascading of aggregation and deaggregation streams . 31 I.1 General . 31 I.2 Deaggregation to deaggregation 31 I.3 Deaggregation to aggregat
27、ion 32 I.4 Aggregation to deaggregation 35 I.5 Aggregation to aggregation 36 Appendix II Potential stream grouping use cases . 38 II.1 Use case #1: alternate speech-text telephony . 38 Bibliography. 47 Rec. ITU-T H.248.96 (11/2015) 1 Recommendation ITU-T H.248.96 Gateway control protocol: ITU-T H.24
28、8 Stream grouping and aggregation 1 Scope As described by the ITU-T H.248 connection model (clause 6 of ITU-T H.248.1) a Termination sources and/or sinks one or more streams. In a multimedia conference, a Termination can be multimedia that sources or sinks multiple media streams. The ITU-T H.248 pro
29、tocol uses the stream concept to model individual media flows. That is, typically, there is one media (and optional control flow) per ITU-T H.248 Stream. The characteristics of each stream are described through the use of the LocalControl, Local Descriptor (LD) and Remote Descriptors (RDs). Each Ter
30、mination contains a group of streams. ITU-T H.248 makes no assumptions as to the relationship between the streams on a Termination other than indicating that streams exiting a Termination shall be synchronised with each other (clause 7.1.4 of ITU-T H.248.1). Certain network technologies may require
31、a media gateway (MG) to have knowledge of how two or more streams relate to each other beyond simply knowing that they shall be synchronised. Where there is a multiplicity of streams there may be a different relation among different sets of streams. For the purposes of this Recommendation, the relat
32、ionship among streams is defined as the grouping semantic. Depending on the grouping semantic the MG may be required to apply certain processing to the media related to the streams. For example: one semantic may indicate that the media is duplicated on separate streams, another semantic may indicate
33、 media is only sent on one of two streams at a time. Some grouping semantics require that media flows from multiple streams are aggregated into a single flow. ITU-T H.248.1 does not support a means to describe grouping semantics. This Recommendation defines the media grouping package that allows a m
34、edia gateway controller (MGC) to group media from two or more ITU-T H.248 Streams according to a particular semantic and optionally to aggregate/deaggregate the media from the grouped streams according to the semantic. The grouping framework in IETF RFC 5888 can, in principle, be applied to any tran
35、sport. It is the actual grouping stream semantics that imposes limitations, i.e., BUNDLE may only be applied to IP transports. As such, the media grouping package and the concept of an ITU-T H.248 aggregation stream can be, in principle, applied to any transport. The majority of defined stream seman
36、tics focus on IP-based transports. As such, this Recommendation describes the semantics with respect to IP. While some semantics may be used for any type of bearer technology the use of the semantics for these bearer technologies are not covered in this Recommendation. 2 References The following ITU
37、-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendatio
38、n are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it,
39、 as a stand-alone document, the status of a Recommendation. ITU-T H.248.1 Recommendation ITU-T H.248.1 (2013), Gateway control protocol: Version 3. ITU-T H.248.7 Recommendation ITU-T H.248.7 (2004), Gateway control protocol: Generic Announcement package. 2 Rec. ITU-T H.248.96 (11/2015) ITU-T H.248.3
40、9 Recommendation ITU-T H.248.39 (2014), Gateway control protocol: ITU-T H.248 SDP parameter identification and wildcarding. ITU-T H.248.47 Recommendation ITU-T H.248.47 (2008), Gateway control protocol: Statistic conditional reporting package. ITU-T H.248.58 Recommendation ITU-T H.248.58 (2008), Gat
41、eway control protocol: Packages for application level H.248 statistics. ITU-T H.248.61 Recommendation ITU-T H.248.61 (2013), Gateway control protocol: Packages for network level ITU-T H.248 statistics. ITU-T H.248.65 Recommendation ITU-T H.248.65 (2009), Gateway control protocol: Support of the reso
42、urce reservation protocol. IETF RFC 3524 IETF RFC 3524 (2003), Mapping of Media Streams to Resource Reservation Flows. IETF RFC 4566 IETF RFC 4566 (2006), SDP: Session Description Protocol. IETF RFC 4588 IETF RFC 4588 (2006), RTP Retransmission Payload Format. IETF RFC 5583 IETF RFC 5583 (2009), Sig
43、naling Media Decoding Dependency in the Session Description Protocol (SDP). IETF RFC 5888 IETF RFC 5888 (2010), The Session Description Protocol (SDP) Grouping Framework. IETF RFC 5956 IETF RFC 5956 (2010), Forward Error Correction Grouping Semantics in the Session Description Protocol. IETF RFC 710
44、4 IETF RFC 7104 (2014), Duplication Grouping Semantics in the Session Description Protocol. 3 Definitions 3.1 Terms defined elsewhere This Recommendation uses the following terms defined elsewhere: 3.1.1 media (section 2.1 of b-IETF RFC 7656, b-ITU-T H.248.95): A sequence of synthetic or physical St
45、imuli (sound waves, photons, key-strokes), represented in digital form. Synthesized media is typically generated directly in the digital domain. 3.1.2 (ITU-T H.248 media) stream (ITU-T H.248.1): Bidirectional media or control flow received/sent by a media gateway as part of a call or conference. 3.1
46、.3 RTP stream (clause 2.1.10 of b-IETF RFC 7656, b-ITU-T H.248.95): A stream of RTP packets containing media data, source or redundant. The RTP stream is identified by an SSRC belonging to a particular RTP session. 3.2 Terms defined in this Recommendation This Recommendation defines the following te
47、rms: 3.2.1 aggregation: The MG internal process of combining two or more component streams on entering the ITU-T H.248 Context in the MG into one single stream, called the aggregation stream. The way the component streams are combined is dependent on the stream grouping semantics defined for the com
48、ponent streams. It may consist of selecting one of the component streams, applying a reparation procedure to one of the component streams based on the information from another component stream, etc. In the reverse direction it may consist on delivering media to only one of them at a time, providing
49、a replica, generating repairing or redundancy information, etc. Rec. ITU-T H.248.96 (11/2015) 3 3.2.2 aggregation stream: A stream that sources media to two or more component streams and/ or sinks media from two or more component streams which are related to each other with a certain stream grouping semantics. The aggregation stream exists only in the interior of the Context whereas the component streams represent external streams. Within one Context a stream m
