【 Weak current College 】 audio, video, related international standards introduction---Power By 【 China power house network 】

International standards are all brands of all kinds of video conference a necessary condition for mutual exchange. IMTC and ITU two defining these standards by the International Committee of the
IMTC: International Multimedia Teleconferencing Alliance is a world-class organizations, including more than 150 companies, to define compatible, based on open standards for multimedia solutions
ITU-International Telecommunication Union (previously known as CCITT: International Telegraph and telephone Consultative Committee) is a branch of the United Nations Headquarters in Geneva. ITU-T (International Telecommunication Union-telecommunications) defines the world telecom standards.

The main criteria defined ITU-T:
H.320: based on link exchange network connections, such as ISDN
H.323: TCP/IP-based packet-switched networks (Ethernet, LAN)
H.324 based on the simulation (telephone) Internet connections. Such networks can not provide video of high-speed data transfer.
T.120: data transfer standard in the H.320 standards under many sub standard defines the audio and video compatibility.

Audio standard:
G.722: it gives 7kHz audio signal needs 64Kb/s. This standard ensures very good sound quality, but the downside is that require a large amount of bandwidth.
G.711: this standard gives an audio signal using 3.4kHz from 32 to 64Kb/s bandwidth
G.728: 3.4kHz audio signal, as long as the compiled on 16Kb/s.

Video standard:
H.261: ITU-T recommended video encoding to P×64Kb/s output. (P in the range 1 to 32). This standard defines the animation quality of two standards: CIF (also for FCIF): 352 x 288 pixel line QCIF (also by 4 × FCIF): 704 lines × 576 pixels
ITU-T H.263: this is in accordance with the recommended for H.320 video coding standard. H.263 restart first H.324 for H.323/design, its encoding quality above H.261, especially suitable for lines in poor condition.

Exchange standards:
H.281: H.320 connection of camera remote control
H.282: H.323 connections under camera remote control

MCU standards:
H.243 defines communication established processes and procedures to control MCU

In addition to introduce our multimedia electronic room key criteria:
--GYJ25-86 the auditoria system performance indicators
--GB4959-95 the auditoria characteristic measurement law
--GBJ76-84 the conferencing system motor and audio performance requirements
--GB/T4197-93 the sound system equipment interconnection application connectors "
--GB/T4197-94 the sound system equipment interconnection with optimum configuration of the connector
--GB/15644-95 audiovisual systems equipment interconnection application connectors >
--GB/15859-1995 audio, video and TV system equipment interconnection optimization with value
--GB12060-89 sound system equipment General terminology explained and calculation methods
-JGJ/T16-92 civil construction electricity design specification
--GBJ232-82 the electrical equipment installation engineering acceptance of
--GA/T74-1994 the People's Republic of China public security industry standards