H320
H.320 is the international ITU standard for video conferencing over ISDN. Several standards are defined for video and audio transmission. For ISDN, the minimum required transmission rate is 64 kbit/s, the maximum 1,920 kbit/s.
The ITU standard is also valid for leased lines with X.21, with a maximum data rate of 2.048 Mbit/s.
H.320, as the higher- level standard, describes the basic technical functions for the terminal equipment, which must fulfill the lower-level standards H.261 for video coding, H. 221 for multiplexing, H. 230, H. 231 and H.243 for multipoint connections and control, as well as the interface according to I.400. This includes the specifications for the codec, packaging and transmission of multimedia data, and signaling. Audio coding is specified according to G.711, G.722 and G.728.
H.320 supports the most important television norms and television standards; the NTSC television standard as well as the PAL television standard.