1、 International Telecommunication Union ITU-T H.230TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (03/2009) SERIES H: AUDIOVISUAL AND MULTIMEDIA SYSTEMSInfrastructure of audiovisual services Systems aspects Frame-synchronous control and indication signals for audiovisual systems Recommendation ITU-T
2、 H.230 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 aspects H.230H.239 Communication procedures H.240
3、H.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 architecture for audiovisual and multimedia services H.3
4、60H.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 Mobile multimedia collaboration applications and se
5、rvices 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.559Mobile multimedia collaboration inter-working procedures H.560H.569 BROADBAND, TRIPLE-PLAY AND
6、 ADVANCED MULTIMEDIA SERVICES Broadband multimedia services over VDSL H.610H.619 Advanced multimedia services and applications H.620H.629 IPTV MULTIMEDIA SERVICES AND APPLICATIONS FOR IPTV General aspects H.700H.719 IPTV terminal devices H.720H.729 IPTV middleware H.730H.739 IPTV application event h
7、andling H.740H.749 IPTV metadata H.750H.759 IPTV multimedia application frameworks H.760H.769 IPTV service discovery up to consumption H.770H.779 For further details, please refer to the list of ITU-T Recommendations. Rec. ITU-T H.230 (03/2009) i Recommendation ITU-T H.230 Frame-synchronous control
8、and indication signals for audiovisual systems Summary Digital audiovisual services are provided by a transmission system in which the relevant signals are multiplexed onto a digital path using the frame structure defined in Recommendation ITU-T H.221. In addition to the audio, video, user data and
9、telematic information, these signals include information for the proper functioning of the system. The additional information has been named control and indication (C means of transmitting numbers and characters; C for simple multipoint conferences not using protocol in the MLP channel; for channel
10、aggregation; and for the transfer of network addresses. The codepoint tables also indicate the circumstances under which the various functions may be mandatory or optional. This revised version of Recommendation ITU-T H.230 introduces a number of enhancements and clarifications to the previous versi
11、on, primarily the description on the usage of Unicode characters and ITU-T G.719 in H.320 systems. Source Recommendation ITU-T H.230 was approved on 16 March 2009 by ITU-T Study Group 16 (2009-2012) under Recommendation ITU-T A.8 procedures. ii Rec. ITU-T H.230 (03/2009) FOREWORD The International T
12、elecommunication 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 an
13、d tariff questions 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 R
14、ecommendations 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 Rec
15、ommendation, 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. interoper
16、ability or 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 c
17、ompliance with 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, vali
18、dity or applicability 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 requ
19、ired to implement 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 2009 All rights reserved. No part of this publication may be reproduc
20、ed, by any means whatsoever, without the prior written permission of ITU. Rec. ITU-T H.230 (03/2009) iii CONTENTS Page 1 Scope 1 2 Procedures 1 2.1 C b) transmission frame-synchronous, or otherwise requiring rapid response; c) conference, data, and telematic control not requiring frame synchronism,
21、governed by the multilayer protocol of Recommendations ITU-T T.122-T.125. This Recommendation concerns only those C LCV, LCD, LCA, LCO (for maintenance). In each case, the code is transmitted in the BAS position at an appropriate time. 2.2 Other C the first letter of this indicates the type; the sec
22、ond is C for command, I for indication; the third is for the specific function. Codepoint values are listed in Tables 1 and 2. For convenience, the occupancy of Table 1 is shown in Table 4. 2.2.1 SBE method The single-byte extension method involves two consecutive BAS codes. In the first, the code (
23、111) 10001 is transmitted. In the second, the code defined in Table 1 is transmitted. It should be noted that only one symbol is transmitted by this method the code in the subsequent sub-multiframe is again treated as a normal BAS code. 2 Rec. ITU-T H.230 (03/2009) 2.2.2 Double and triple SBE symbol
24、s A “double symbol“ consists of two SBE code-pairs, the second immediately following the first. The first is one of the symbols listed as having an associated SBE number or SBE character parameter to be conveyed by the second. Thus, a double symbol occupies four successive BAS positions, and takes 8
25、0 ms to transmit. A “triple symbol“ similarly consists of three SBE code-pairs in succession; the first is one of the symbols listed as having an associated numerical or character parameter to be conveyed by the second and third. Thus, a triple symbol occupies six successive BAS positions, and takes
26、 120 ms to transmit. A “quadruple symbol“ consists of four SBE code-pairs in succession, occupies eight successive BAS positions, and takes 160 ms to transmit. In the case of TII*1, it may be double or triple, or longer, but the succession of symbols shall end with the symbol TIS. 2.2.3 MBE method T
27、he multiple-byte extension method involves three or more consecutive BAS codes, in the following format: Start-MBE / N / / (N 1) bytes where: Start-MBE is specified in Table A.1/H.221; N is a binary number in the range 1223; is a value from Table 2. 3 Definitions of C terminals may repeat a request
28、that an MCU has already satisfied. It is important that terminals receiving SBE symbols that they do not recognize or cannot use shall ignore these and not enter any fault recovery process. Rec. ITU-T H.230 (03/2009) 11 MCV Multipoint Command Visualization-forcing Transmitted by a terminal to force
29、an associated MCU to broadcast its video signal used to transmit the picture of a chairman or VIP, alternatively to hold a picture source during the transmission of graphics. MIV Multipoint Indication Visualization Transmitted by an MCU to indicate to a terminal that its video signal is being seen b
30、y at least one other terminal (otherwise known as “On-air“ or “SeenByAtLeastOneOther“ indication). MVC Multipoint Visualization Capability Included in the cap-set of an MCU or terminal to show that it can properly generate or process the codes MVA and MVR. MVA Multipoint Visualization Achieved Trans
31、mitted by an MCU to indicate that it has granted visualization in response to the command MCV. MVR Multipoint Visualization Refused/Revoked Transmitted by an MCU when it cannot comply with the command MCV, when visualization status has been withdrawn due to a higher priority switch request, e.g., VC
32、B, or as a response to Cancel-MCV. MCC Multipoint Command Conference Transmitted by an MCU. An endpoint receiving MCC shall make its outgoing transfer rate equal to its incoming transfer rate, and its outgoing audio rate equal to its incoming audio rate. NOTE 1 The command could also be used to invo
33、ke an on-screen user indication. MCS Multipoint Command Symmetrical data-transmission Transmitted by an MCU when setting up data broadcasting. On receipt, a terminal shall prepare itself for data reception and ensure, by mode change if necessary, that its outgoing data channel occupies the same capa
34、city as its incoming data channel. A terminal in receipt of MCS cannot initiate data broadcasting. MCN Multipoint Command Negating MCS Transmitted by an MCU at the completion of data broadcasting. On receipt, a terminal shall close any outgoing data channel which it has opened as a result of the pre
35、vious reception of MCS. Following the end of data reception and the receipt of MCN, a terminal is permitted to initiate data broadcasting. MMS Multipoint command Mode-Symmetrize Transmitted by an MCU. When in receipt of MMS, endpoints shall respond to the MCU with whatever mode they receive, includi
36、ng audio coding algorithm and rate, data path(s), and video coding algorithm and image format, and also image Profile in the case of Rec. ITU-T H.262. NOTE 2 If MMS has not been received, terminals are free to follow the mode asymmetry allowed by MCC, e.g., to send H.263 while receiving H.261. MIZ M
37、ultipoint Indication Zero-communication Transmitted by an MCU to a terminal for information, with the meaning that no other terminals are yet connected to the MCU. MIS Multipoint Indication Secondary-status Transmitted by an MCU to a terminal for information, with the meaning that since other termin
38、als of higher capability are participating in the conference-call, this terminal will not necessarily receive all the signals that are sent to those other terminals (see Rec. ITU-T H.243). MIM Multipoint Indicate Master-MCU Transmitted by an MCU which has claimed the master-MCU role. MIL* Multipoint
39、 Indication Loop See clause 10 of Rec. ITU-T H.243; shall be followed by an SBE number. MIH Multipoint Indicate Hierarchy This capability value indicates that the MCU can operate as a master, a slave, or a sub-slave, in a multi-level hierarchy. MIJ Multipoint Indicate Joined_Real_Conference Sent by
40、an MCU to a terminal to indicate that the terminal has joined an actual conference, and that any terminal numbers or identifiers previously transmitted are no longer valid. RAN* Random Number Must be followed by a random SBE number in the range 0-223. TIA* Terminal Indicate Assignment Used by an MCU
41、 to transmit the assigned terminal number to another MCU or to a terminal; shall be followed by . 12 Rec. ITU-T H.230 (03/2009) TIN* Terminal Indicate Number Used to pass information concerning terminal number assignments made; shall be followed by . TIL Terminal Indicate List MBE message used to tr
42、ansmit list of terminal numbers currently added into the conference; the message has the form start-MBE/N/(N 2) values of , where has the value given in Table 2, is a one-byte number assigned to an MCU, and each value of is a one-byte value assigned to a terminal by its local MCU. One such message w
43、ill be sent for each MCU participating. TID* Terminal Indicate Dropped Used to pass information concerning any terminal number no longer effective; shall be followed by . TCU Terminal Command Update Transmitted by a terminal or MCU to an MCU to request an updated list of terminals connected. TIF* Te
44、rminal Indicate Floor-request Transmitted by a terminal to its MCU; shall be followed by when forwarded from one MCU to another, is that of the terminal requesting the floor; when transmitted by the terminal itself, shall follow. TIC Terminal Indicate Capability Included in the initial cap-set of a
45、terminal to tell an MCU that it can recognize TIA and return TIX in the additional channels; included in the cap-set of an MCU to say that it can accept additional calls to the same access number and correctly associate additional channels according to the procedure described in Rec. ITU-T H.243. TI
46、X* Terminal Indicate additional-channel-X Sent by a terminal having capability TIC in response to TIA; shall be followed by . TCI Terminal Command Identify Sent by an MCU to a directly-connected terminal or vice versa to exact identification by means of a symbol TII*. TCS-n Terminal Command String S
47、ent by an MCU to a directly-connected terminal or vice versa to exact information in the form of a symbol IIS; the meaning according to the different values of n is thus: n = 0: reserved n = 1: password n = 2: ASCII identity (person or terminal) n = 3: conference identity n = 4: extension address n
48、= 5: Unicode identity (person or terminal) n = 6 to 31: reserved TII* Terminal Indicate Identity Sent in response to TCI; shall be followed by an SBE alphanumeric character according to clause 3.4, the content being prescribed by the MCU service provider. IIS Information Indicate String An MBE messa
49、ge sent in response to TCS-n; the message has the form start-MBE/N/(N 2) characters where has the value given in Table 2, where n corresponds to the value of n in TCS-n; characters are as specified for TIP. When n = 5, the message has the form start-MBE/N/languageID/(N 4) characters where languageID and characters are as specified for TIP-5. TIS Terminal Indicate identity-Stop End-marker to indicate the end of a sequence of TII symbols.
