1、ETSI TECHNICAL REPORT ETR 176 December 1995 Source: ETSI TC-TE Reference: DTR/TE-O1050 ICs: 33,35.180 Key words: multimedia, interworking, interoperabiliiy, retrieval services, audiovisual services, Videotex - Terminal Equipment (TE); Interworking and interoperabiltiy of retrieval services and audio
2、visual services on narrow band networks ETSI European Telecommunications Standards Institute ETSI Secretariat Postal address: F-O6921 Sophia Antipolis CEDEX - FRANCE Office address: 650 Route des Lucioles - Sophia Antipolis - Valbonne - FRANCE X.400: c=fr, a=atlas, p=etsi, s=secretariat - Internet:
3、secretariata etsi.fr Tel.: +33 92 94 42 O0 - Fax: +33 93 65 47 16 Copyright Notification: No part may be reproduced except as authorized by written permission. The copyright and the foregoing restriction extend to reproduction in all media. Q European Telecommunications Standards Institute 1995. All
4、 rights resewed. Whilst every care has been taken in the preparation and publication of this document, errors in content, typographical or otherwise, may occur. If you have comments concerning its accuracy, please write to “ETSI Editing and Committee Support Dept.“ at the address shown on the title
5、page. ETSI ETR*lb 95 3400855 0073386 52T . Page 3 ETR 176: December 1995 Contents . Foreword . 7 1 Scope 9 2 References 9 3 Definitions and abbreviations 11 3.1 Definitions 11 3.2 Abbreviations . 12 4 Interworking environment 12 4.1 Retrieval services . 12 4.2 Audiovisual conversational services . 1
6、3 4.3 Multipoint services 13 4.4 Terminal equipment and networks 13 5 PSTN videotelephony terminal 14 5.1 Terminal without data-facility 14 5.1.1 Access to a PSTN videotelephony service centre . 15 5.1.1.1 Description . 15 5.1.1.2 Applications . 15 5.1.1.3 Constraints . 15 5.1.1.4 Protocols 15 Acces
7、s to a Videotex service centre . 15 5.1.2.1 Description . 15 5.1.2.2 Applications . 16 5.1.2.3 Constraints . 16 5.1.2.4 Protocols 16 5.1.2.5 Interworking Unit (IWU) . 16 Terminal with data-facility . 17 5.2.1 5.2.2 Access to a Videotex service centre . 17 5.2.2.1 Description . 17 5.2.2.2 Application
8、s . 17 5.2.2.3 Constraints . 17 5.2.2.4 Protocols 18 5.2.2.5 Interworking Unit . 18 5.1.2 5.2 Access to a PSTN videotelephony service centre . 17 6 ISDN terminals 18 Videotex terminal enhanced with H.261 18 6.1.1 Description . 18 6.1.2 Applications 19 6.1.3 Constraints . 19 6.1.4 Protocols 19 Combin
9、ed Videotex and AV(D) terminal . 19 6.2.1 Access to an ITU-T Recommendation H.320 service centre 20 6.2.2 Access to a Videotex service centre . 20 6.2.3 Access to a Videotex/AV(D) service centre . 20 6.2.3.1 Description . 20 6.2.3.2 Applications . 20 6.2.3.3 Constraints . 20 6.2.3.4 Protocols 21 H.3
10、20 terminal without data-facility . 21 6.3.1 Access to an H.320 service centre 22 Description . 22 6.3.1.1 Applications . 22 6.3.1.2 6.1 6.2 6.3 ETSI ETR*L7b 95 D 3400855 0073187 4bb Page 4 ETR 176: December 1995 7 6.4.2.1 6.4.2.2 6.4.2.3 6.4.2.4 6.3.1.3 Constraints 22 6.3.1.4 Protocols . . 23 Acces
11、s to a Videotex service centre 23 6.3.2.1 Description 23 6.3.2.2 Applications 23 6.3.2.3 Constraints 23 6.3.2.4 Protocols . 24 6.3.2.5 Interworking Unit 24 H.320 terminal with data-facility . 24 6.4.1 Without Videotex decoder . 24 6.4.1.1 Access to an H.320 service centre 24 6.4.1.1.1 Description 24
12、 6.4.1.1.2 Applications . 25 6.4.1.1.3 Constraints 25 6.4.1.1.4 Protocols . 25 Access to a Videotex service centre 25 6.4.1.2.1 Description 25 6.4.1.2.2 Applications . 25 6.4.1.2.3 Constraints 26 6.4.1.2.4 Protocols . 26 6.4.1.2.5 Interworking Unit 26 Access to a Videotex centre via an MCU 26 6.4.1.
13、3.1 Description 26 6.4.1.3.2 Applications . 27 6.4.1.3.3 Constraints 27 6.4.1.3.4 Protocols . 27 6.4.1.3.5 Interworking Unit 27 6.4.1.3.6 MCU 27 With Videotex decoder 27 Access to an H.320 service centre 28 6.4.2.1.1 Description 28 6.4.2.1.2 Applications . 28 6.4.2.1.3 Constraints 28 6.3.2 6.4 6.4.1
14、.2 6.4.1.3 6.4.2 6.4.2.1.4 Protocols . 29 Access to a Videotex service centre 29 6.4.2.2.1 Description 29 6.4.2.2.2 Applications . 29 6.4.2.2.3 Constraints 29 6.4.2.2.4 Protocols . 29 6.4.2.2.5 Interworking Unit 29 6.4.2.3.1 Description 30 6.4.2.3.2 Applications . 30 6.4.2.3.3 Constraints 30 6.4.2.3
15、.4 Protocols . 30 6.4.2.3.5 Interworking Unit 31 Access to a Videotex centre via an MCU 31 6.4.2.4.1 Description 31 6.4.2.4.2 Applications . 31 6.4.2.4.3 Constraints 31 6.4.2.4.4 Protocols . 32 6.4.2.4.5 Interworking Unit 32 6.4.2.4.6 MCU 32 Access to a Videotex/AV(D) service centre . 30 Scenario an
16、d terminal relevance 32 7.1 Classification of terminals 32 7.1.1 Technical aspects 33 7.1.2 User aspects 35 7.2 Interactive protocols 36 7.3 Overall conclusions on scenarios 38 7.4 Overall conclusion on terminal types . 38 7.4.1 Short term interest . 38 7.4.2 Midlong term interest 39 ETSI ETRU176 95
17、 3400855 0073LBB 3T2 W Page 5 ETR 176: December 1995 Annex A: Considerations for H.320 terminals with MLP 40 History 41 - Page 6 ETR 176: December 1995 - ETSI ETR*176 95 3Y00855 0073389 239 m Blank page ETSI ETRr17b 95 3400855 0073390 T50 Page 7 ETR 176: December 1995 Foreword This ETSI Technical Re
18、port (ETR) has been produced by the Terminal Equipment (TE) Technical Committee of the European Telecommunications Standards Institute (ETSI). ETRs are informative documents resulting from ETSI studies which are not appropriate for European Telecommunication Standard (ETS) or Interim European Teleco
19、mmunication Standard (LETS) status. An ETR may be used to publish material which is either of an informative nature, relating to the use or the application of ETSs or I-ETSs, or which is immature and not yet suitable for formal adoption as an ETS or an LETS. ETSI ETR*37b 95 = 3400855 0073393 997 W P
20、age 8 ETR 176: December 1995 Blank page 1 Scope This ETR studies interworking and interoperability between retrieval services (Videotex, possibly including moving video) and audiovisual services (videotelephony, videoconferencing) on narrow band networks (Integrated Services Digital Network (ISDN) a
21、nd Public Switched Telephone Network(PSTN). Retrieval services include Videotex information retrieval applications possibly including moving video and applications based on retrieval of videotelephony ITU-T Recommendations H.320 14 and H.261 17 coded information. - The interworking and interoperabil
22、ity of retrieval services and audiovisual services support applications consisting of combinations of Videotex, videotelephony and/or videoconferencing applications. The services under consideration are Videotex, videotelephony and videoconferencing. This ETR investigates possible scenarios of inter
23、working and interoperability between retrieval services and audiovisual services on narrow band networks and the requirements on Terminal Equipment (TE). 2 References This ETR incorporates by dated or undated reference, provisions form other publications. These references are cited at the appropriat
24、e places in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this ETR only when incorporated in it by amendment or revision. For undated references the latest edition of the application referred to a
25、pplies. NOTE 1: NOTE 2: 131 i41 51 ETS 300 145: “Integrated Services Digital Network (ISDN); Audiovisual services; Videotelephone systems and terminal equipment operating on one or two 64 kbits channels“. ETS 300 145 is the ETSI equivalent of ITU-T Recommendation H.320 14. The scope of ETS 300 145 i
26、s restricted to 1B and 2B ISDN videophones. ETS 300 144: “Integrated Services Digital Network (ISDN), Audiovisual services, Frame structure for a 64 kbis to 1 920 kbit/s channel and associated syntax for inband signalling“. ETS 300 144 is the ETSI equivalent to ITU-T Recommendations H.221 15 and H.2
27、30 16. CCITT Recommendation 6.1 3 (1 988): “Terms and definitions“. ITU-T Recommendation F.300 (1 993): “Videotex service“. ETS 300 142: “Integrated Services Digital Network (ISDN) and other digital telecommunications networks; Line transmission of non-telephone signals; Video codec for audiovisual
28、services at p * 64 kbit/s ITU-T Recommendation H.261 (1 993) modified“. ETS 300 072: “Terminal Equipment (TE); Videotex presentation layer protocol, Videotex layer data syntax“. ETS 300 149: “Terminal Equipment (TE); Videotex; Audio syntax“. ETS 300 177: “Terminal Equipment (TE); Videotex; Photograp
29、hic syntax“. Draft ITU-T Recommendation T.120: “Transmission protocol for multimedia data“. ETC 300 143 (1994) and Al: “Integrated Services Digital Network (ISDN); Audiovisual services; Inband signalling procedures for audiovisual terminals using digital channels up to 2 048 kbits“. ETSI ETR*L76 95
30、9 3400855 0073193 76T m Page 10 ETR 176: December 1995 LETS 300 380 (1 995): “Universal Personal Telecommunication (UPT); Access devices Dual Tone Multi-Frequency (DTMF) sender for acoustic coupling to the microphone of a handset telephone“. ITU-T Recommendation H.231 (1 993): “Multipoint control un
31、its for audiovisual systems using digital channels up to 2 Mbis“. ITU-T Recommendation H.243: “System for Establishing Communication Between Three or More Audiovisual Terminals Using Digital Channels up to 2 Mbis“. ITU-T Recommendation H.320: “Narrow-band Visual Telephone Systems and Terminal Equipm
32、ent“. ITU-T Recommendation H.221: “Frame structure for a 64 to 1920 kbitls channels in audiovisual services“. ITU-T Recommendation H.230 (1 995): “Frame-synchronous controls and indications for audiovisual systems“. ITU-T Recommendation H.261 (1 993): “Video codec for audiovisual services at P x 64
33、kbis“. ETS 300 O01 : “Attachments to the Public Switched Telephone Network (PSTN); General technical requirements for equipment connected to an analogue subscriber interface in the PSTN“. ITU-T Recommendation T.122: Multipoint communication service for audiographics and audiovisual conferencing serv
34、ice definition“. ITU-T Recommendation T.123: “Protocol stacks for audiographic and audiovisual teleconference applications“. ITU-T Recommendation T.124: “Generic Conference Control“. ITU-T Recommendation T.125: “Multipoint communication service protocol specification“. ITU-T Recommendation X.25 (1 9
35、93): “Interface between data terminal equipment (DTE) and data circuit-terminating equipment (DCE) for terminals operating in the packet mode and connected to public data networks by dedicated circuit“. CCITT Recommendation G.711 (1988): “Pulse code modulation (PCM) of voice frequencies“. CCITT Reco
36、mmendation G.722 (1 988): “7 kHz audio coding within 64 kbis“ CCITT Recommendation G.728 (1992): “Coding of speech at 16 kbis using low-delay code excited linear prediction“. ITU-T Recommendation H.224 (1 994): “A real-time control protocol for simplex applications using the H.221 LSD/HSD/MLP channe
37、ls“. ETSI ETR*17b 95 3400855 0073394 bTb = Page 11 ETR 176: December 1995 3 Definitions and abbreviations 3.1 Definitions For the purposes of this ETR, the following definitions apply. audtovisuai conversational service: An interactive service which provides for bi-directional communication by means
38、 of real-time (no store-and-forward) end-to-end audiovisual information transfer from user to user or between user and host. Combined Videotex and Audio-Visual (Data) (AV(D) terminal: A TE that consists of a combination of an ISDN Videotex terminal and an ITU-T Recommendation H.320 I41 terminal. Bot
39、h logical terminals can be active each at a time or together. When operated together, each terminal part will use a B-channel, or two B-channels are allocated for use by H.320 and the ISDN D-channel for use by a Videotex protocol. H.320 terminal without data-facility: A TE that conforms to the metho
40、ds described in ETS 300 145 l, but does not offer data capabilities. In the scope of this ETR it implies that the terminal is at least capable of receiving audio and video sent in a framed structure (ETS 300 144 2). And that the terminal is at least capable of sending audio and video in a framed str
41、ucture (ETS 300 144 2). H.320 terminal with data-facliity: A TE that conforms to the methods described in ETS 300 145 I. In the scope of this report it implies that the terminal is at least capable of receiving audio, video and data sent in a framed structure (ETS 300 144 2). And that the terminal i
42、s at least capable of sending audio, video and data in a framed structure (ETS 300 144 2). interactive protocol: A means to interact between the terminal and service centre on the application layer. Interworking Unit (IWU): A unit that transforms information streams according to the appropriate prot
43、ocols. PSTN vfdeotelephony terminal: A TE that is able to exchange audio, video (still or moving images) and possibly data over the PSTN. retrieval service: An interactive service which provides the capability of accessing information stored in databases centres. The information will be sent to the
44、user on demand only. The information can be retrieved on an individual basis, .e., the time at which an information sequence is to start under the control of the user (CCITT Recommendation 8.13 3). service centre: A computer system used by a service provider to authorise access to a service. Other f
45、unctions of the service centre may include assistance to users in selecting the particular application required (either provided by the service centre or by other host computers), as well as management facilities such as billing, statistics gathering, etc. The same computer may also be a host comput
46、er and/or provide a gateway function (definition derived from ITU-T Recommendation F.300 4). Videotex terminal enhanced with H.261: A TE that uses the Videotex protocols over the ISDN network and, in addition, is able to decode and represent video images encoded according to the schemes defined in E
47、TC 300 142 5. - ETSI ETR*:L7b 95 3400855 0073195 532 D Page 12 ETR 176: December 1995 3.2 Abbreviations For the purposes of this ETR, the following abbreviations apply. AP AV AVD BAS CIF DB DTMF HSD ISDN IWU LS D MCU MLP PC PSPDN PSTN QCIF SBV TE TFI uus VPh ws Access Point Audio Visual Audio Visual
48、 Data Bitrate Allocation Signal Common Intermediate Format Data Base Dual Tone Multi Frequency High Speed Data Integrated Services Digital Network Interworking Unit Low Speed Data Multiple Control Unit Multi Layer Protocol Personal Computer Packet Switched Public Data Network Public Switched Telepho
49、ne Network Quarter Common Intermediate Format Syntax Based Videotex Terminal Equipment Terminal Facility Identifier User-To-User Signalling Videotelep hony Work Station 4 Interworking environment This ETR examines the interworking between interactive services with retrieval facility and audiovisual conversational services. The approach taken describes a number of existing and predictable terminal types for audiovisual conversational services in view of communication with retrieval services. For each terminal type, the scenarios for accessing an
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