1、CCITT RECMN*H.200 (REV+L) 93 W 48b2591 0580441 93T W INTERNATIONAL TELECOMMUN KATION UN ION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU LINE TRANSMISSION OF NONITELEPHONE SIGNALS H.200 (03193) FRAMEWORK FOR RECOMMENDATIONS FOR AUDIOVISUAL SERVICES ITU-T Recommendation H.200 (Previously “CC
2、IlT Recommendation”) CCITT RECMN*H.200 (REV*L) 93 48b259L 0580442 87b m FOREWORD The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of the International Telecom- munication Union. The ITU-T is responsible for studying technical, operating and tariff questions and issuing R
3、ecommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Conference (WTSC), which meets every four years, established the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these
4、topics. ITU-T Recommendation H.200 was revised by the ITU-T Study Group XV (1988-1993) and was approved by the WTSC (Helsinki, March 1-12, 1993). NOTES 1 As a consequence of a reform process within the International Telecommunication Union (IT), the CCITT ceased to exist as of 28 February 1993. In i
5、ts place, the ITU Telecornmuunication Standardization Sector (U-T) was created as of 1 March 1993. Similarly, in this reform process, the CCIR and the IFRB have been replaced by the Radiocommunication Sector. In order not to delay publication of this Recommendation, no change has been made in the te
6、xt to references containing the acronyms ?CCITT, CCIR or IFRl3? or their associated entities such as Plenary Assembly, Secretariat, etc. Future editions of this Recommendation will contain the proper terminology related to the new ITU structure. 2 telecommunication administration and a recognized op
7、erating agency. In this Recommendation, the expression ?Administration? is used for conciseness to indicate both a O IT 1993 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, wit
8、hout permission in writing from the ITU. CCITT RECMN*H.ZOO (REV+L) 93 B 4862593 0580443 702 = CONTENTS 1 Audiovisual services 1 2 Harmonization of audiovisual services . 1 1 Purpose of this Recommendation . 4 Framework 2 5 List of audiovisual services covered 2 6 List of networks covered 2 Annex A -
9、 Framework for Recommendations for audiovisual services Page 3 3 Recommendation H.200 (03/93) i CCITT RECMN*H=200 (REVtli) 93 4862593 0580444 649 Recommendation H.20 FRAMEWORK FOR RECOMMENDATIONS FOR AUDIOVISUAL SERVICES (Melbourne, 1988; amended a Helsinki, 1993) 1 Audiovisual services A number of
10、services are, or will be, defined in CCITT having as their common characteristic the transmission of speech together with other information reaching the eventual user in visual form. This Recommendation concerns a set of such services which should be treated in a harmonized way; it is convenient to
11、refer to the members of this set as “audiovisual services (abbreviated to AV services). 2 Harmonization of audiovisual senices While the various audiovisual services may easily be distinguished in terms of their user-application, common methods are used for the transport of signais representing spee
12、ch, moving or still pictures, and associated controls/indications, and also telematic auxiliary facilities. The standardization process seeks the greatest possible harmonization of these common features, confining the distinction to the application iayers wherever possible, in order to: a) Maximize
13、the possibilities for intercommunication between terminals intended for different applications; b) Maximize the commonality of hardware and software in the interests of economies of scale. The mpe for commonality includes: audio and video inpudoutput parameters, audio and video codecs, the controlhd
14、ication set, frame structures and multiplexing, call control procedures (including multipoint). The embodiment of this harmonization policy will be a consistent set of Recommendations, consistent in the sense that ail members of the set take into account ail other members. 3 Purpose of this Recommen
15、dation The purpose of this Recommendation is to define the set that shall be consistent. In fulfilling this function it is important to distinguish, at a given time, between Recommendations and draft Recommendations. Recommendations are members of the set by virtue of their consistency with other ad
16、opted members of the set: these are listed in Annex A. It is of course necessary to ensure continued consistency when amendments are introduced. Draft Recommendations range from mere titles or outline contents through varying stages of maturity to a stable final draft. As many different intended mem
17、bers of the RecommendationH.200 set are developed in parailel to ensure consistency they should be treated as “provisional” members of the set. The list of set members including provisional items does not form part of this Recommendation, but this Recommendation should be updated in the future to in
18、clude new members of the set formally adopted. Recommendation H.20 (03/93) 1 CCITT RECMNxH-200 (REV*1) 93 4862591 0580445 585 4 Framework Recommendations in the H.200 set are arranged in hree main sections: a) Service demitions - These specify the service as seen by the user, including basic service
19、, optional enhancements, quality, and intercommunication requirements, together with operational aspects; technical implementation methods are taken into munt but not defined herein. b) Znfratructure - This section includes ali the Recommendations which are applicable to two or more distinct service
20、s: these encompass network configuration, frame structures, control/indications, communicationlintunication, and audidvideo coding. The “infrasaucture” includes this generality of signals which flow on unrestricted digital bearers on established network connections - it does not include the methods
21、of cai1 establishment and control, orchesirated by signals outside these bearers. Systems and terminui equipment - This section deals with the technical implementation of specific services: it therefore includes service-specinc equipment for the application iayer, and draws upon the infrastructure R
22、ecommendations to identify the detailed processes requked for the particular service. An “other aspects” section is included, covering such maers as cai control, including aspects which are particular to AV services but, some involving out-of-band signais, do not come within the scope of the infkasr
23、ucture section above. c) 5 List of audiovisual services covered The following audiovisual services sha be included in the harmonized set: - - - - - audiographic teleconferencing; - - telesurveiiiance. narrowband videophone (p x 64 kbit/s); broadband videophone (a teleservice For broadband ISDN); nar
24、rowband videoconferencing (p x 64 kbids); broadband videoconferencing (a teleservice for broadband ISDN); telephony (a degenerate case of an AV service, included for intercommunication purposes); The following audiovisual services are in the process of being defined, and consideration should be give
25、n to their inclusion in the set for either of the reasons given in 2. - videomail, - - videoretrieval; - high resolution image retrieval; - distribution services. videotex (including pictures and sound); 6 List of networks covered The possible use of the following networks is taken into account: - I
26、SDN (basic and primary access); - B-ISDN (Ushg ATM); - analogue (PSTN); - LANs (e.g. FDDI); - mobildradio; - leased lines (digital). 2 Recommendation H.200 (03/93) CCITT RECMN*H-200 (REV*L) 93 m 4862593 058044b 433 Annex A (to Recommendation H.200) Framework for Recommendations for audiovisual servi
27、ces (This annex forms an integral part of this Recommendation) A.l Service definition AV. 100 AV.101 AV.110 AV.111 AV.120 AV.121 AV. 122 AV. 130 AV.131 AV.132 AV.140 AV.150 AV.160 AV.161 General AV services Teleconference service General principles for audiographic conference service Audiographic co
28、nference service Videotelephony services - General Basic narrow band videophone service in the ISDN Broadband videotelephony services Videoconference service - General Videoconference services - General Broadband videoconference services Audiovisual interactive services - General (Other AV services
29、not yet defined) (Audiovisual service applications) Service oriented requirements for telewriting applications Recommendation No. Draft available E701 (F.710 in Blue Book) F.7 10 F.711 F.720 F.721 F.722 F.730 E732 F.740 F.761 (F.730 in Blue Book) A.2 Infrastructure AV.200 AV.210 AV.220 AV.221 AV.230
30、 AV.23 1 AV.232 AV.233 AV.240 AV.241 AV.242 AV.243 AV.250 AV.251 (General AV infrastructure) (Reference networks) (Transmission multiplex structure) Frame structure for a 64 to 1920 kbWs channel in audiovisual teleservices Frame-synchronous control and indication signals for audiovisual systems Mult
31、ipoint control units for audiovisual systems using digital channels up to 2 Mbit/s (Broadband multipoint control) Confidentiality system for audiovisual services (Communication - Principles) System aspects for the use of the 7 kHz audio codec within 64 kbit/s System for establishing communication be
32、tween audiovisual terminals using digital channels up to 2 Mbit/s Procedures for establishing communication between three or more audiovisual terminals using digital channels up to 2 Mbit/s (Audio coding) Pulse code modulation (EM) of voice frequencies H.221 H.230 H.23 1 H.233 G.725 H.242 H.243 G.71
33、1 Recommendation Ha00 (0-3) 3 CCITT RECMN*H.200 (REV*&) 93 W V8b2591 0580447 358 W AV.252 AV.253 AV.254 AV.255 AV.260 AV.261 AV.262 AV.263 AV.264 AV.266 AV.270 AV.271 AV.272 AV.273 AV.274 AV.280 AV.290 AV.29 1 A.3 AV.300 AV.310 AV.3 11 AV.320 AV.321 AV.330 AV.331 A.4 AV.400 AV.410 AV.420 AV.440 4 7
34、kHz audio-coding within 64 kbit/s (Audio coding at 24/32 kbit/s) Coding of speech at 16 kbit/s using low-delay code excited linear prediction Audio coding for storagdreaieval (Video coding) Video codec for audiovisual services at p x 64 kbit/s (Video coding for use on B-ISDN) Video coding for storag
35、dretrieval up to about 1 Mbit/s (Video coding for storage/retrieval at less than 10 Mbids) (Video coding for distribution) Overview of AGC Recommendations Audiographic conferencing Generic conference control Protocol stach for audiographic and audiovisual teleconference applications Multipoint Commu
36、nications service (For future purposes) (interworking with preexisting systems) (interworking with H.120D-I.130 systems) Systems and terminal equipment (General AV systemdkrmhals) (TC systems and equipment) Audiographic teleconference Visual telephone systems and equipment (Broadband visual telephon
37、e) (Equipment for AV retrieval, systems) Broadcasting type multipoint systems G.728 MPEG audio (DIS 11 172 Part 3) H.261 WEG-1 Video (DIS 11172 Part 2) WEG-2 T.120 . T.121 T.124 T. 123 T.122 Draft available H.320 H.33 1 Other aspects (other aspects) (Reservation systems) Call control (including multipoint) (Multipoint ca set-up) NOTE - Entries in parentheses are indicative of the purpose of the various positions in the framework. Recommendation H.200 (03B3)
