1、 International Telecommunication Union ITU-T H.248.19TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (03/2013) SERIES H: AUDIOVISUAL AND MULTIMEDIA SYSTEMSInfrastructure of audiovisual services Communication procedures Gateway control protocol: Decomposed multipoint control unit, audio, video and da
2、ta conferencing packages Recommendation ITU-T H.248.19 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 a
3、spects H.230H.239 Communication procedures H.240H.259Coding 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 architect
4、ure for audiovisual and multimedia services H.360H.369 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 services H.510H.519 Mobi
5、le 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 collaboration inter-working
6、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 SERVICES AND APPLICATIONS
7、 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 Signage H.780H.789 For fu
8、rther details, please refer to the list of ITU-T Recommendations. Rec. ITU-T H.248.19 (03/2013) i Recommendation ITU-T H.248.19 Gateway control protocol: Decomposed multipoint control unit, audio, video and data conferencing packages Summary Recommendation ITU-T H.248.19 describes the functionality
9、of a decomposed multipoint control unit, in particular the interface between a media controller and media processor which is based on Recommendation ITU-T H.248.1. This Recommendation contains guidelines for the use of a decomposed gateway that may support audio, video and data conferencing. This Re
10、commendation contains packages for floor control, volume control, video windows, audio and video mixing for point-to-point, multi-cast and hybrid conferencing scenarios. This revision incorporates corrections to fix a duplicated binary Release Event identity and a duplicated Result parameter binary
11、identity. History Edition Recommendation Approval Study Group 1.0 ITU-T H.248.19 2004-03-15 16 1.1 ITU-T H.248.19 (2004) Amd. 1 2006-05-29 16 1.2 ITU-T H.248.19 (2004) Amd. 2 2009-03-16 16 2.0 ITU-T H.248.19 2013-03-16 16 ii Rec. ITU-T H.248.19 (03/2013) FOREWORD The International Telecommunication
12、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 question
13、s 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 Recommendations on
14、 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, the
15、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 or appl
16、icability) 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 with
17、the Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTS ITU 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 applica
18、bility 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 impleme
19、nt 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 2013 All rights reserved. No part of this publication may be reproduced, by any mean
20、s whatsoever, without the prior written permission of ITU. Rec. ITU-T H.248.19 (03/2013) 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 2 5 Conferencing architecture . 2 6 Sp
21、eaking and listening in a conference 4 7 Determination and management of conferencing capabilities 4 8 Simultaneous support of media types . 5 9 MCUs and multiplexed media bearers . 5 10 Floor control . 5 10.1 Floor Control Package 6 10.2 Floor Action Package . 8 10.3 Indication of being viewed pack
22、age . 8 10.4 Floor Control Policy Package . 10 10.5 Floor Status Change Handling Package . 12 10.6 Floor Control Signalling Package 15 11 Audio conferencing 18 11.1 Volume Control Package 18 11.2 Volume Detection Package 19 11.3 Volume Level Mixing Package 20 11.4 Mixing Volume Level Control Package
23、 . 21 11.5 Include Participant in Mix Package 23 11.6 Speaker Reporting Package 24 12 Video conferencing . 26 12.1 Voice Activated Video Switch Package . 26 12.2 Lecture Video Mode Package 29 12.3 Contributing Video Source Package 30 12.4 Video Window Package . 32 12.5 Tiled Window Package . 35 12.6
24、 Text Overlay Package . 37 12.7 Border and Background Package . 42 13 Data conferencing . 43 13.1 Chat and messaging conferencing 43 13.2 Additional data conferencing . 44 Bibliography. 45 Rec. ITU-T H.248.19 (03/2013) 1 Recommendation ITU-T H.248.19 Gateway control protocol: Decomposed multipoint c
25、ontrol unit, audio, video and data conferencing packages 1 Scope The scope of this Recommendation is the interface between the media controller and media processor in a decomposed multipoint control unit. This Recommendation does not describe the call control functions associated with conferencing s
26、ervices nor does it describe the capabilities of terminals. The specification of service information for “Dial in“ or “Dial out“ conferences (e.g., meet me numbers) is out of scope of this Recommendation. It is also assumed that the media controller part of the multipoint control unit is responsible
27、 for the management of conference identities. This Recommendation describes packages and functions associated with the ITU-T H.248 interface for audio, video and data conferencing. This includes the specification of mixing, conference capabilities and core ITU-T H.248.1 protocol usage. The packages
28、and functionality described in this Recommendation are optional according to the rules of ITU-T H.248.1. A multipoint control unit may implement one or more of the packages described in this Recommendation. 2 References The following ITU-T Recommendations and other references contain provisions whic
29、h, 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 Recommendation are therefore encouraged to investigate the possibility of ap
30、plying 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, as a stand-alone document, the status of a Recommendation. ITU
31、-T H.248.1 Recommendation ITU-T H.248.1 (2013), Gateway control protocol: Version 3. ITU-T H.248.2 Recommendation ITU-T H.248.2 (2013), Gateway control protocol: Facsimile, text conversation and call discrimination packages. ITU-T H.248.10 Recommendation ITU-T H.248.10 (2001), Gateway control protoc
32、ol: Media gateway resource congestion handling package. ITU-T H.248.27 Recommendation ITU-T H.248.27 (2003), Gateway control protocol: Supplemental tones packages. ITU-T T.140 Recommendation ITU-T T.140 (1998), Protocol for multimedia application text conversation. IETF RFC 4376 IETF RFC 4376 (2006)
33、, Requirements for Floor Control Protocols. IETF RFC 4582 IETF RFC 4582 (2006), The Binary Floor Control Protocol (BFCP). IETF RFC 4583 IETF RFC 4583 (2006), Session Description Protocol (SDP) Format for Binary Floor Control Protocol (BFCP) Streams. 2 Rec. ITU-T H.248.19 (03/2013) 3 Definitions 3.1
34、Terms defined elsewhere This Recommendation uses the following terms defined elsewhere: None. 3.2 Terms defined in this Recommendation This Recommendation defines the following terms: 3.2.1 listener: The user/endpoint who is receiving media. 3.2.2 speaker: The user/endpoint who is sending media. 3.2
35、.3 local image: The image of user A that is sent to user B. 3.2.4 remote image: The image of user B that user A receives. 3.2.5 floor: A permission to temporarily access or manipulate a specific shared resource or set of resources. 3.6 floor chair (floor controller): A logical entity that manages on
36、e floor (grants, denies or revokes a floor). 3.7 floor participant: A logical entity that requests floors. 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms: BFCP Binary Floor Control Protocol BNF Backus-Naur Form FCFS First-Come First-Served MC Media Con
37、troller MCU Multipoint Control Unit MP Media Processor SDP Session Description Protocol SIP Session Initiation Protocol TDM Time Division Multiplex 5 Conferencing architecture A multipoint control unit allows the mixing of one or more input streams of various media into one or more output streams of
38、 various media. A decomposed MCU is comprised of two components: the Media Controller (MC) and the Media Processor (MP). The Media Controller terminates call control signalling (e.g., ITU-T H.225, SIP) and is responsible for controlling the MP. It is also responsible for the service logic of any con
39、ferencing (e.g., it indicates the floor controller). The MP is responsible for initiating and terminating media streams. In the case of conferencing, it provides mixing, transcoding functions and, if necessary, any additional media-related functions. ITU-T H.248 is used between a media controller an
40、d media gateway, which also contain similar functions; thus, ITU-T H.248 may be used in a decomposed MCU. Figure 1 shows a decomposed MCU. Rec. ITU-T H.248.19 (03/2013) 3 H.248.19 (13)_F01Media Controller(MC)Media Processor(MP)Decomposed MCUITU-TH.248Figure 1 Decomposed MCU The ITU-T H.248.1 model a
41、llows for different types of conferencing. Typically, an MCU controls what is termed “multipoint“ conferences in ITU-T H.32x systems or using SIP terminology “lecture mode“, “dial-in“ or “dial-out“ conferences. An MCU may also control what is termed “point-to-point“ conferences in ITU-T H.32x system
42、s or using SIP terminology “end system mixing“ or “centralized signalling“. However, for the point-to-point mode, the MC will control the conference without any extra conferencing functionality needed to be implemented in the MP. Clause 6 of ITU-T H.248.1 describes the connection model. By placing t
43、he relevant terminations in the same or different contexts, it allows the MCU to perform the different types of “multipoint“ conferencing. Figure 2 shows the ITU-T H.248 modelling of a “Lecture mode“ conference. Termination A represents the “speaker“; terminations B, C or D represent the “listening“
44、 terminations. Stream 1 represents an audio stream and the stream mode is used to determine who “speaks“ and who “listens“. H.248.19-Amd.2(09)_F02MPContextTermination AStream 1 (Audio)Stream Mode (Receive)Termination BStream 1 (Audio)Stream Mode (Send)Termination CStream 1 (Audio)Stream Mode (Send)T
45、ermination DStream 1 (Audio)Stream Mode (Send)MixFigure 2 “Lecture mode“ conference Figure 3 shows the ITU-T H.248 modelling of a “Dial-in“ or “Dial out“ conference. The MP is unaware of the difference between “Dial-in“ and “Dial-out“ conferencing. All the terminations have both “speaking“ and “list
46、ening“ capabilities. Stream 1 represents a video stream. Stream mode of send/receive indicates that the user represented by the termination is both a “speaker“ and “listener“. 4 Rec. ITU-T H.248.19 (03/2013) H.248.19-Amd.2(09)_F03MPContextMixTermination AStream 1 (Video)Stream Mode (Send/Receive)Ter
47、mination BStream 1 (Video)Stream Mode (Send/Receive)Termination CStream 1 (Video)Stream Mode (Send/Receive)Termination DStream 1 (Video)Stream Mode (Send/Receive)Figure 3 Multipoint conference An example of the use of multiple contexts to perform a conference is when there is a centralized conferenc
48、e and a party is put on hold. According to the ITU-T H.248.1 connection model, a separate context is used for the held party. This results in a hybrid conference with two contexts. Another example on the use of multiple contexts is when there is a main conference in one context and side conference i
49、n another context. Rather than moving all the participants into one context, a separate call leg termination in both contexts may be used to join the conferences. As a result of the support of multiple context conferences, a conference bridge may be modelled as a central context with a side context for each call leg to a participant. 6 Speaking and listening in a conference As part of a conference who “speaks“ and who “listens“ may need to be controlled. This is achieved by setting the stream mode of the stream repre
