Audiovisual Services – Framework
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Audiovisual Services – Framework
A number of 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 H.200 concerns a set of such services which should be treated in a harmonized way; it is convenient to refer to the members of this set as ” audiovisual services “(abbreviated to AV services).
Framework
Recommendations in the H.200 set are arranged in three main sections:
- Service definitions – These specify the service as seen by the user, including basic service, optional enhancements, quality, and intercommunication requirements, together with operational aspects; technical implementation methods are taken into account but not defined herein.
- Infrastructure – This section includes all the Recommendations which are applicable to two or more distinct services: these encompass network configuration, frame structures, control/indications, communication/intercommunication, and audio/video coding. The “infrastructure” includes this generality of signals which flow on unrestricted digital bearers on established network connections – it does not include the methods of call establishment and control, orchestrated by signals outside these bearers.
- Systems and terminal equipment – This section deals with the technical implementation of specific services: it, therefore, includes service-specific equipment for the application layer and draws upon the infrastructure Recommendations to identify the detailed processes required for the particular service.
An “other aspects” section is included, covering such matters as call control, including aspects which are particular to AV services but, some involving out-of-band signals, do not come within the scope of the infrastructure section above.
Framework for Recommendations for audiovisual services
A.1 | Service definition | Recommendation No |
AV.100 | General AV services | Draft available |
AV.101 | Teleconference service | F.701 (F.710 in Blue Book) |
AV.110 | General principles for audiographic conference service | F.710 |
AV.111 | Audiographic conference service | F.711 |
AV.120 | Videotelephony services – General | F.720 |
AV.121 | Basic narrow band videophone service in the ISDN | F.721 |
AV.122 | Broadband videotelephony services | F.722 |
AV.130 | Videoconference service – General | F.730 |
AV.131 | Videoconference services – General |
|
AV.132 | Broadband videoconference services | F.732 |
AV.140 | Audiovisual interactive services – General | F.740 |
AV.150 | (Other AV services not yet defined) |
|
AV.160 | (Audiovisual service applications) |
|
AV.161 | Service-oriented requirements for telewriting applications | F.761 (F.730 in Blue Book) |
A.2 | Infrastructure | Recommendation No |
AV.200 | (General AV infrastructure) |
|
AV.210 | (Reference networks) |
|
AV.220 | (Transmission multiplex structure) |
|
AV.221
| A frame structure for a 64 to 1920 kbit/s channel in audiovisual teleservices | H.221 |
AV.230
| Frame-synchronous control and indication signals for audiovisual systems | H.230 |
AV.231
| Multipoint control units for audiovisual systems using digital channels up to 2 Mbit/s | H.231
|
AV.232 | (Broadband multipoint control) | H.233 |
AV.233 | Confidentiality system for audiovisual services |
|
AV.240 | (Communication – Principles) |
|
AV.241 | System aspects for the use of the 7 kHz audio codec | G.725
|
AV.242 | System for establishing communication between audiovisual terminals using digital channels up to | H.242
|
AV.243 | Procedures for establishing communication between | H.243
|
AV.250 | (Audio Coding) |
|
AV.251 | Pulse code modulation (PCM) of voice frequencies | G.711 |
AV.252 | 7 kHz audio-coding within 64 kbit/s | G.722 |
AV.253 | (Audio coding at 24/32 kbit/s) |
|
AV.254 | Coding of speech at 16 kbit/s using low-delay code | G.728
|
AV.255 | Audio coding for storage/retrieval | MPEG audio (DIS 11172 Part 3) |
AV.260 | (Video Coding) |
|
AV.261 | Video codec for audiovisual services at p × 64 kbit/s | H.261 |
AV.262 | (Video coding for use on B-ISDN) |
|
AV.263 | Video coding for storage/retrieval up to about | MPEG-1 Video (DIS 11172 Part 2) |
AV.264 | (Video coding for storage/retrieval at less than | MPEG-2 |
AV.266 | (Video coding for distribution) |
|
AV.270 | Overview of AGC Recommendations | T.120 |
AV.271 | Audiographic conferencing | T.121 |
AV.272 | Generic conference control | T.124 |
AV.273 | Protocol stacks for audiographic and audiovisual teleconference applications | T.123
|
AV.274 | Multipoint communications service | T.122 |
AV.280 | (For future purposes) |
|
AV.290 | (Interworking with pre-existing systems) |
|
AV.291 | (Interworking with H.120/H.130 systems) |
|
A.3 | Systems and terminal equipment | Recommendation No |
AV.300 | (General AV systems/terminals) |
|
AV.310 | (TC systems and equipment) |
|
AV.311 | Audiographic teleconference | Draft available |
AV.320 | Visual telephone systems and equipment | H.320 |
AV.321 | (Broadband visual telephone) |
|
AV.330 | (Equipment for AV retrieval, systems) |
|
AV.331 | Broadcasting type multipoint systems | H.331 |
A.4 | Other aspects | Recommendation No |
AV.400 | (Other aspects) |
|
AV.410 | (Reservation systems) |
|
AV.420 | [Call control (including multipoint)] |
|
AV.440 | (Multipoint call set-up) |
|
List of audiovisual services covered
The following audiovisual services shall be included in the harmonized set:
- narrowband videophone (p × 64 kbit/s);
- broadband videophone (a teleservice for broadband ISDN);
- narrowband videoconferencing (p × 64 kbit/s);
- broadband video conferencing (a teleservice for broadband ISDN);
- audiographic teleconferencing;
- telephony (a degenerate case of an AV service, included for intercommunication purposes);
- telesurveillance
The following audiovisual services are in the process of being defined, and consideration should be given to their inclusion in the set for either of the reasons given in 2.
- video mail;
- videotex (including pictures and sound);
- video retrieval;
- high-resolution image retrieval;
- distribution services.
List of networks covered
The possible use of the following networks is taken into account:
- ISDN (basic and primary access);
- B-ISDN (using ATM);
- analogue (PSTN);
- LANs (e.g. FDDI);
- mobile/radio;
- leased lines (digital).
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