Add files using upload-large-folder tool

marked/H/T-REC-H.100-198811-I_PDF-E/raw.md

@@ -0,0 +1,236 @@
+
+
+![ITU logo](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) features the letters 'ITU' in a bold, sans-serif font, superimposed on a stylized globe with latitude and longitude lines.
+
+ITU logo
+
+INTERNATIONAL TELECOMMUNICATION UNION
+
+**ITU-T**
+
+**H.100**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**LINE TRANSMISSION  
+OF NON-TELEPHONE SIGNALS**
+
+---
+
+**VISUAL TELEPHONE SYSTEMS**
+
+**ITU-T Recommendation H.100**
+
+(Extract from the *Blue Book*)
+
+---
+
+# NOTES
+
+1 ITU-T Recommendation H.100 was published in Fascicle III.6 of the *Blue Book*. This file is an extract from the *Blue Book*. While the presentation and layout of the text might be slightly different from the *Blue Book* version, the contents of the file are identical to the *Blue Book* version and copyright conditions remain unchanged (see below).
+
+2 In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+# **VISUAL TELEPHONE SYSTEMS**
+
+*(former Recommendation H.61, Geneva, 1980;  
+amended at Malaga- Torremolinos, 1984  
+and at Melbourne, 1988)*
+
+## **1 Definition**
+
+The **visual telephone service** is generally a two-way telecommunication service which uses a switched network of broadband analogue and/or digital circuits to establish connections among subscriber terminals, primarily for the purpose of transmitting live or static pictures.
+
+Special application one-way systems, e.g. surveillance and some information retrieval systems, or a non-switched videoconference service, can be regarded as degenerate cases of the visual telephone service.
+
+The visual telephone service also includes the associated speech.
+
+## **2 Facilities to be offered**
+
+The design of the visual telephone service shall be such as to offer at least the following basic facilities:
+
+- a) Transmission of live pictures such as head and shoulders of one person or a small group of persons, with moderate definition.
+- b) Transmission of the associated speech.
+- c) Transmission of graphics information such as drawings and documents with high definition (e.g. 625 lines or 525 lines).
+- d) Video conference service, with or without the use of split-screen techniques.
+
+The above-mentioned services shall, in general, be bi-directional, although uni-directional operation should be possible. Also, some of the facilities can be omitted, if not required, in order to minimize costs.
+
+*Note* – At the subscriber terminal, the use of ancillary equipments, e.g. for document reproduction, video tape recordings, etc., shall be possible.
+
+## **3 System parameters**
+
+### **3.1 Picture standards**
+
+3.1.1 The video standards of the subscriber sets shall be compatible with, readily convertible to, or identical to, the local broadcast television standards.
+
+3.1.2 Two classes of picture standards are recommended for the visual telephone system. They are given in Table 1/H.100.
+
+TABLE 1/H.100
+
+#### **Picture standards**
+
+| Class    | Items                                         | The region to which the figures should be applied         |                                                           |
+|----------|-----------------------------------------------|-----------------------------------------------------------|-----------------------------------------------------------|
+|          |                                               | Regions where TV broadcasting uses 25 pictures per second | Regions where TV broadcasting uses 30 pictures per second |
+| <i>a</i> | Number of horizontal scanning lines . . . . . | 625                                                       | 525                                                       |
+|          | Pictures per second . . . . .                 | 25<br>(2:1 interleaved)                                   | 30<br>(2:1 interleaved)                                   |
+|          | Aspect ratio . . . . .                        | 4:3                                                       | 4:3                                                       |
+|          | Video bandwidth. . . . .                      | 5 MHz                                                     | 4 MHz                                                     |
+| <i>b</i> | Number of horizontal scanning lines . . . . . | 313                                                       | 263                                                       |
+|          | Pictures per second . . . . .                 | 25<br>(2:1 interleaved)                                   | 30<br>(2:1 interleaved)                                   |
+|          | Aspect ratio . . . . .                        | 4:3                                                       | 4:3                                                       |
+|          | Video bandwidth . . . . .                     | 1 MHz                                                     | 1 MHz                                                     |
+
+Class *a* standards are identical to the local broadcast video standards and will, in most cases, give sufficient definition for real-time picture transmission of a group of people (e.g. for conferencing) and of graphics material.
+
+Class *b* standards give sufficient definition for real-time transmission of a head and shoulder picture of one person or a small group. For the transmission of graphics information or other still pictures with high definition, a slow-scan technique has to be applied. For instance, a system using 625 or 525 horizontal scanning lines and 5, or less, pictures per second which gives a Class *a* definition in the 1 MHz bandwidth.
+
+Further study is required to define slow scanning parameters.
+
+## 4 Characteristics relating to split-screen techniques for Class *a* television conference systems<sup>1)</sup>
+
+In television conference systems which use split-screen techniques to make more effective use of the picture area, the following features for the terminals and transmitted signals are recommended. Preferred seating arrangement for such systems are given in Annex A.
+
+### 4.1 *Picture format*
+
+The transmitted picture should be 4 : 3 aspect ratio, split into upper and lower halves corresponding to the groups of seats. Viewed from the camera system, the left-hand group should be in the upper half and the right-hand group in the lower half.
+
+The split should occur at the end of lines 166 and 479 for 625-line television systems and at the end of line 142 in Field 1 and line 141 in Field 2 for 525-line television systems, as shown in Figure 1/H.100.
+
+Before display, the receive equipment may discard half lines and first and last lines which are liable to be averaged during standards conversion or vertical aperture correction of mixed signals.
+
+### 4.2 *Identification signal for split-screen system*
+
+#### 4.2.1 *Analogue video signals*
+
+The identification signal for split-screen system should be inserted in the vertical blanking period, because the control is required for each television frame or field.
+
+<sup>1)</sup> Split-screen techniques for systems using Class *b* standards require future study.
+
+The line where the identification signal is inserted and its signal format are under study.
+
+#### 4.2.2 *Digital video signals*
+
+An identification signal for split-screen system should be provided. In the case of codecs in Recommendations H.120 and H.130 the format shall be that specified in Recommendation H.130.
+
+### 4.3 *Compatibility with non-split-screen systems*
+
+The simplest kind of a video telephone terminal is composed of a single camera and other equipments. These terminals may be interconnected with split-screen system terminals. In that case, mechanical masks (if used) for the two split-screen displays (aspect ratio = 4 : 1.5) need to be removed, or if a display with 4 : 3 aspect ratio needs to be installed additionally.
+
+### 4.4 *Cameras and displays arrangement*
+
+The entrance pupils of the TV camera optical system should be as near as possible to the centre of the TV display showing remote conferees, in order to minimize errors in eye contact angle.
+
+Unless means are employed to place these pupils in line with the display, e.g. by use of half-silvered mirrors, the camera system should be sited above the display and central to it.
+
+In order to keep the maximum horizontal errors as small as possible, the cameras used had better be in a cross-fire system, as for example in Figure A-1/H.100, and the camera/display assembly should be sited on the central axis of the terminal. However, in some cases, adoption of parallel-fire system as shown also in Figure A-1/H.100 is necessary due to a restriction in equipment arrangement.
+
+Whether the two cameras are arranged in cross-fire or parallel-fire is left open to each Administration since the selection does not affect the interconnection of different systems.
+
+### 4.5 *Picture processing methods at transmitting terminals*
+
+In order to obtain the correct relationship between the signals from the two cameras for split-screen working, the cameras should be synchronized but the vertical drive pulses should be rephased. The drive to one should be advanced by one quarter of the vertical period while the drive to the other should be retarded by the same amount. This causes a central strip of the target of each camera tube to be used and so minimizes the effects of distortions in the corners of the targets. Figure B-1a)/H.100 illustrates the preferred method.
+
+Alternative methods which are not recommended although they do not give rise to problems of end-to-end compatibility are compared in Annex B.
+
+### 4.6 *Receiving equipment*
+
+The receiving equipment should be capable of working with discontinuities in the received signal that may be caused by switching between non-synchronous video sources.
+
+*Note* – A split-screen device should be capable of working with a codec with the input and output frequency tolerances as specified in Recommendation H.120.
+
+![Diagram of the 625-line television system vertical format. It shows two fields, Field 1 and Field 2, each divided into 'Left hand Group' and 'Right hand Group'. Line numbers are marked at the top: 23 1/2, 166, 167, 310, 336, 479, 480, 623 1/2. The number of lines for each segment is marked at the bottom: 25, 143 1/2, 144, 25, 144, 143 1/2. The total number of lines for each field is 312 1/2.](547f726730e589392f239257a833ede3_img.jpg)
+
+Diagram of the 625-line television system vertical format. It shows two fields, Field 1 and Field 2, each divided into 'Left hand Group' and 'Right hand Group'. Line numbers are marked at the top: 23 1/2, 166, 167, 310, 336, 479, 480, 623 1/2. The number of lines for each segment is marked at the bottom: 25, 143 1/2, 144, 25, 144, 143 1/2. The total number of lines for each field is 312 1/2.
+
+Left hand group: first complete lines 24 and 336  
+last complete lines 166 and 479  
+Right hand group: first complete lines 167 and 480  
+last complete lines 310 and 622
+
+Lines 16-20 inclusive and 329-333 inclusive may contain identification, control or test signals.
+
+#### *a) 625-line television system*
+
+![Diagram of the 525-line television system vertical format. It shows two fields, Field 1 and Field 2, each divided into 'Left hand Group' and 'Right hand Group'. Line numbers are marked at the top: 22, 142, 143, 263 1/2, 21 1/2, 141, 142, 262. The number of lines for each segment is marked at the bottom: 21, 121, 120 1/2, 21, 120 1/2, 121. The total number of lines for each field is 262 1/2. A small code 'CCITT-32372' is visible at the bottom right.](f6d72d7c790e7f585532140f3971639a_img.jpg)
+
+Diagram of the 525-line television system vertical format. It shows two fields, Field 1 and Field 2, each divided into 'Left hand Group' and 'Right hand Group'. Line numbers are marked at the top: 22, 142, 143, 263 1/2, 21 1/2, 141, 142, 262. The number of lines for each segment is marked at the bottom: 21, 121, 120 1/2, 21, 120 1/2, 121. The total number of lines for each field is 262 1/2. A small code 'CCITT-32372' is visible at the bottom right.
+
+Left hand group: first complete lines 22 (Field 1, 2)  
+last complete lines 142 (Field 1), 141 (Field 2)  
+Right hand group: first complete lines 143 (Field 1), 142 (Field 2)  
+last complete lines 262 (Field 1, 2)
+
+Lines 10-21 inclusive in Field 1 and 9 1/2-21 1/2 inclusive in Field 2 may contain identification, control or test signals.
+
+#### *b) 525-line television system*
+
+*Note 1* — The method of defining the line number is following Fig. 2-1 of CCIR Report 624 for 625 system, and Fig. 2-3 for 525 system.
+
+*Note 2* — The notation which is used for line numbers is as follows. Line 23 1/2 means that the picture starts (or finishes) half-way along line number 23. When totalling lines, a half-line is shown separately, e.g. 143 + 1/2.
+
+FIGURE 1/H.100  
+Vertical format of split-screen video signal
+
+## ANNEX A (to Recommendation H.100)
+
+### **Seating arrangements when applying split-screen techniques for class a system**
+
+Preferred arrangements for video conferences using split-screen techniques are:
+
+A.1 The conference terminal accommodation should be for 6 primary seats in two adjacent groups of 3 as shown in Figure A.1/H.100.
+
+Provision for additional seating behind may be made, so long as allowance is made for the central gap between the two halves. For example, 4 additional persons may be seated on a second row as in the Figure.
+
+A.2 The chairman's position should be in the centre of the left-hand group of seats (viewed from the camera) with user controls accessible from both this position and the one of the chairman's left.
+
+Consequently, when split-screen pictures are displayed, stacked as received (i.e. shown as 3 over 3), the chairman's position is standardized as top centre.
+
+The suite of 3 chairs containing the chairman's position should also be regarded as the primary position for occasions when only half of a studio is in use. Such standardization is necessary for connection of 3 studios in conference using time-division multiplex of pairs of TV signals to share a common trunk between two studios.
+
+![Studio plan view diagram showing seating arrangements and camera positions.](9791722d75115ddcc599b07d7bc35d73_img.jpg)
+
+The diagram illustrates a studio plan view for video conferencing. It shows a semi-circular arrangement of seats divided into two main groups: 'Primary seating (2 groups of 3)' and 'Secondary seating (2 groups of 2)'. The 'Preferred position for chairman' is marked in the center of the left-hand primary seating group. A 'Desk' is positioned in front of the seating area. Two 'Cameras' are shown on the right, with 'Optical axes' indicated by dashed lines. The cameras are labeled 'CCITT - 32351'. The diagram is divided into 'Top half scene' and 'Bottom half scene' by a horizontal line. A note indicates that solid line cameras are for cross-fire and dashed line cameras are for parallel-fire. The total seating in camera is 6 primary and 4 secondary.
+
+Studio plan view diagram showing seating arrangements and camera positions.
+
+*Note* – Solid line cameras are for cross-fire. Dashed line cameras are for parallel-fire.
+
+FIGURE A-1/H.100  
+Studio plan view
+
+## ANNEX B
+
+(to Recommendation H.100)
+
+### **Picture processing methods in transmitting terminals**
+
+Alternative methods of obtaining the split-screen signal which are compatible with the recommended method and which might be useful for experiments and demonstrations are shown in *b)* and *c)* of Figure B-1/H.100. In method *b)*, the two cameras are directed upward and downward to pick up right and left halves of the conferencing room, respectively. Since circumferences of target and scanning areas are used, geometric and brightness distortions tend to occur. In method *c)*, vertical deflection currents are biased by the quantity corresponding to  $\pm 1/4$  of target height. Vertical deflection bias adjustment is needed every time cameras are exchanged. In method *a)*, the vertical driving pulses are phase-shifted by  $\pm 1/4$  V. The recommended method, *a)*, avoids the problems of methods *b)* and *c)*.
+
+![Diagram (a) showing vertical driving pulses being phase shifted. A camera on the left points to two processing blocks labeled 'Shifted VD1' and 'Shifted VD2'. These blocks output to two intermediate frames showing people. The top frame has regions labeled B' and B, with a dashed line between them. The bottom frame has regions labeled A' and A, also with a dashed line. Both intermediate frames then point to a final frame on the right, which is divided into regions A and B by a dashed line.](ebff22fb5dd6f50a90e44dca0f82f285_img.jpg)
+
+Diagram (a) showing vertical driving pulses being phase shifted. A camera on the left points to two processing blocks labeled 'Shifted VD1' and 'Shifted VD2'. These blocks output to two intermediate frames showing people. The top frame has regions labeled B' and B, with a dashed line between them. The bottom frame has regions labeled A' and A, also with a dashed line. Both intermediate frames then point to a final frame on the right, which is divided into regions A and B by a dashed line.
+
+a) Vertical driving pulses are phase shifted
+
+![Diagram (b) showing cameras directed upward and downward. A camera on the left has two output paths labeled 'Up' and 'Down'. The 'Up' path goes to a processing block and then to a frame with regions B' and B. The 'Down' path goes to a block labeled 'VD' and then to a frame with regions A' and A. Both frames point to a final frame on the right divided into regions A and B.](562f471e8153729557e6a4ee6343c32c_img.jpg)
+
+Diagram (b) showing cameras directed upward and downward. A camera on the left has two output paths labeled 'Up' and 'Down'. The 'Up' path goes to a processing block and then to a frame with regions B' and B. The 'Down' path goes to a block labeled 'VD' and then to a frame with regions A' and A. Both frames point to a final frame on the right divided into regions A and B.
+
+b) Cameras are directed upward and downward
+
+![Diagram (c) showing vertical deflection currents being biased. A camera on the left points to two processing blocks. The top block outputs to a frame with a 'Scan area' (top part) and a 'Target area' (bottom part), labeled with B' and B. The bottom block, labeled 'VD', outputs to a frame with regions A' and A. Both frames point to a final frame on the right divided into regions A and B. The text 'CCITT-49981' is in the bottom right corner.](7a0db9703b68b3d06cdaeefc084c0006_img.jpg)
+
+Diagram (c) showing vertical deflection currents being biased. A camera on the left points to two processing blocks. The top block outputs to a frame with a 'Scan area' (top part) and a 'Target area' (bottom part), labeled with B' and B. The bottom block, labeled 'VD', outputs to a frame with regions A' and A. Both frames point to a final frame on the right divided into regions A and B. The text 'CCITT-49981' is in the bottom right corner.
+
+c) Vertical deflection currents are biased
+
+VD = vertical deflection
+
+FIGURE B-1/H.100  
+Picture processing method at transmitting terminals

marked/H/T-REC-H.200-199303-I_PDF-E/raw.md

@@ -0,0 +1,221 @@
+
+
+![ITU logo: A globe with a lightning bolt and the letters ITU.](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg)
+
+ITU logo: A globe with a lightning bolt and the letters ITU.
+
+INTERNATIONAL TELECOMMUNICATION UNION
+
+**ITU-T**
+
+**H.200**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+(03/93)
+
+**LINE TRANSMISSION  
+OF NON-TELEPHONE SIGNALS**
+
+---
+
+**FRAMEWORK FOR RECOMMENDATIONS  
+FOR AUDIOVISUAL SERVICES**
+
+**ITU-T Recommendation H.200**
+
+(Previously "CCITT Recommendation")
+
+---
+
+# FOREWORD
+
+The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of the International Telecommunication Union. The ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations 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 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 (ITU), the CCITT ceased to exist as of 28 February 1993. In its place, the ITU Telecommunication Standardization Sector (ITU-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 text to references containing the acronyms "CCITT, CCIR or IFRB" 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 In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+# CONTENTS
+
+|                                                                        | <i>Page</i> |
+|------------------------------------------------------------------------|-------------|
+| 1 Audiovisual services .....                                           | 1           |
+| 2 Harmonization of audiovisual services .....                          | 1           |
+| 3 Purpose of this Recommendation.....                                  | 1           |
+| 4 Framework .....                                                      | 2           |
+| 5 List of audiovisual services covered .....                           | 2           |
+| 6 List of networks covered.....                                        | 2           |
+| Annex A – Framework for Recommendations for audiovisual services ..... | 3           |
+
+
+
+# **FRAMEWORK FOR RECOMMENDATIONS FOR AUDIOVISUAL SERVICES**
+
+*(Melbourne, 1988; amended at Helsinki, 1993)*
+
+## **1 Audiovisual services**
+
+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 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).
+
+## **2 Harmonization of audiovisual services**
+
+While the various audiovisual services may easily be distinguished in terms of their user-application, common methods are used for the transport of signals representing speech, 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 layers wherever possible, in order to:
+
+- a) Maximize 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 scope for commonality includes: audio and video input/output parameters, audio and video codecs, the control/indication 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 all members of the set take into account all other members.
+
+## **3 Purpose of this Recommendation**
+
+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 adopted 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 members of the Recommendation H.200 set are developed in parallel 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 include new members of the set formally adopted.
+
+## 4 Framework
+
+Recommendations in the H.200 set are arranged in three main sections:
+
+- a) *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.
+- b) *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.
+- c) *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.
+
+## 5 List of audiovisual services covered
+
+The following audiovisual services shall be included in the harmonized set:
+
+- narrowband videophone ( $p \times 64$  kbit/s);
+- broadband videophone (a teleservice for broadband ISDN);
+- narrowband videoconferencing ( $p \times 64$  kbit/s);
+- broadband videoconferencing (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.
+
+## 6 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).
+
+# Annex A
+
+(to Recommendation H.200)
+
+## Framework for Recommendations for audiovisual services
+
+(This annex forms an integral part of this Recommendation)
+
+## A.1 Service definition
+
+*Recommendation No.*
+
+|        |                                                            |                                       |
+|--------|------------------------------------------------------------|---------------------------------------|
+| AV.100 | General AV services                                        | Draft available                       |
+| AV.101 | Teleconference service                                     | F.701 (F.710<br>in <i>Blue Book</i> ) |
+| 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<br>in <i>Blue Book</i> ) |
+
+## A.2 Infrastructure
+
+|        |                                                                                                                             |       |
+|--------|-----------------------------------------------------------------------------------------------------------------------------|-------|
+| AV.200 | (General AV infrastructure)                                                                                                 |       |
+| AV.210 | (Reference networks)                                                                                                        |       |
+| AV.220 | (Transmission multiplex structure)                                                                                          |       |
+| AV.221 | 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)                                                                                              |       |
+| AV.233 | Confidentiality system for audiovisual services                                                                             | H.233 |
+| 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<br>(DIS 11172 Part 3)   |
+| AV.260 | (Video coding)                                                               |                                    |
+| AV.261 | Video codec for audiovisual services at $p \times 64$ 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<br>(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
+
+|        |                                        |                 |
+|--------|----------------------------------------|-----------------|
+| 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
+
+|        |                                       |  |
+|--------|---------------------------------------|--|
+| AV.400 | (Other aspects)                       |  |
+| AV.410 | (Reservation systems)                 |  |
+| AV.420 | [Call control (including multipoint)] |  |
+| AV.440 | (Multipoint call set-up)              |  |
+
+NOTE – Entries in parentheses are indicative of the purpose of the various positions in the framework.