Yong Qiu Liu's Web Page--H.324

Networking service systems and related standards

*2. Network conferencing standards*
ITU has provided a series of network conferencing recommendations to specify their network configurations, video, audio codecs, data communications and other related aspects.	The commonly used conferencing standards are H.324 POTS video phone standard, H.320 ISDN conferencing standard and H.323 LAN videoconferencing standard.

2.1 H.324 Video phone standard

H.324 is an ITU (the International Telecommunications Union) recommendation that provides a foundation for interoperability and video, voice and data based phone calls. It specifies a common method for video, voice and data to be shared simultaneously over high speed modem connections. H.324 is the first standard to specify interoperability over a single analogue line.

H.324 uses a normal 28,800 bps V.80 modem connection between callers. It uses H.263 as its digital video compression method and G.723.1 as its voice compression method.

The maximum data rate is limited by the modem used, which is 28.8 Kbps. Where the bandwidth of the voice is around 6 Kbps and the rest bandwidth is devoted to the video and data ^[15].

The quantity of the voice is the same like the normal telephone, but the quality of the video is not as good as TV quality. Having only a 176 * 132 pixel window at the each end of the caller. Also the speed of the video picture is around 4 to 12 frames per second — nearly half the rate of that of a normal TV picture.

Last update April 1, 2002