1
Scope
2 Definitions
3 System description
3.1 Block diagram and identification
of elements
3.2 Signals
3.3 Bit rate options and
infrastructure
3.3.1 Communication modes of visual telephone
3.3.2 Terminal types of visual telephone
3.3.3 Video codec
3.3.4 Audio codec
3.3.5 Frame structure
3.3.6 Control and Indication (C&I)
3.3.7 Communication procedure
3.4 Call control arrangements
3.4.1 Establishment of a visual telephone call – Normal procedure
3.4.2 Exceptional procedures for phases A and B
3.4.3 Exceptional procedures during phase C
3.4.4 Addition and dropping of channels during a visual telephone call
3.4.5 Transmission and presentation of audiovisual information at the start
of a visual telephone call
3.5 Optional enhancements
3.5.1 Data ports
3.5.2 Encryption
3.5.3 Restricted networks
4 Terminal requirements
4.1 Environments
4.2 Audio and video arrangements
4.2.1 Audio arrangements
4.2.2 Video arrangements
4.3 Delay compensation in the audio
path
4.4 Control and Indications (C&I)
4.5 Multipoint operation
5 Intercommunications
5.1 Intercommunication between
different visual telephone terminal types
5.2 Intercommunication with telephony
5.2.1 Intercommunication with ISDN telephones
5.2.2 Intercommunication with PSTN telephones
5.3 Intercommunication with other
audiovisual terminals
5.3.1 Intercommunication with H.324 terminals on GSTN
5.3.2 Intercommunication with H.322
terminals on Guaranteed QoS LANs
5.3.3 Intercommunication with H.323 terminals on Non‑guaranteed QoS
LANs
5.3.4 Intercommunication with H.310/H.321 terminals on ATM networks
6 Maintenance
7 Human factor aspects
7.1 Physical section
7.2 Logical section
Annex A – Optional enhanced video algorithms for H.320
systems
A.1 Introduction to enhanced video
algorithms
A.2 Use of Recommendation H.262 in H.320 systems
A.2.1 Image formats
A.2.2 Forward error correction
A.2.3 Syntax and semantics of video frame synchronous C&I
A.2.4 Generic usage of ITU‑T_extension()
A.3 Use of Recommendation H.263 in
H.320 systems
A.4 Enhanced video algorithm hierarchy