Videoconferencing Standards

H.320

The dominant videoconferencing standard developed by the ITU-T (International Telecommunications Union-Telecommunications Standards Section). It is a standard for describing videoconferencing terminals, but the term H.320 has come to represent a whole suite of specifications for enabling a compliant videoconferencing session. It was originally adopted for room-based videoconferencing and for digital lines such as ISDN.

H.261

The compression component of H.320. It specifies a range of intraframe and interframe compression algorithms that can work with Px64 digital channels (64 Kbps to 2.048 Mbps).

CIF

Common Intermediate Format. The optional high-resolution display format at 352- pixel (horizontal) by 288-pixel (vertical) resolution.

QCIF

Quarter CIF. The minimum display format of 176-pixel (hori zontal) by 144-pixel (vertical) resolution.

H.231 and H.243

These standards cover MCUs (Multipoint Control Units). H.231 defines how three or more H.320-com-patible videoconferencing systems link together in a single conference. H.243 defines the MCU protocol standard.

H.233 and H.KEY

H.233 specifies the data-encryption methodologies supported under H.320. H.KEY standardizes the electronic management of encryption keys.

T.120

A standard-in-development, T.120 will cover document-sharing protocols. Once T.120 is adopted, compliant whiteboard applications will be able to talk to one another. Today, you must have the same whiteboard software on both ends of a conference.