audiovisual services

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:

  1. 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.
  2. 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.
  3. 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
within 64 kbit/s

G.725

 

AV.242

System for establishing communication between audiovisual terminals using digital channels up to
2
Mbit/s

H.242

 

AV.243

Procedures for establishing communication between
three or more audiovisual terminals using digital
channels up to 2 Mbit/s

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
excited linear prediction

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
1 Mbit/s

MPEG-1 Video

(DIS 11172 Part 2)

AV.264

(Video coding for storage/retrieval at less than
10 Mbit/s)

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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