Video Conferencing

The next dimension in Internet communication is the videophone.

Video conferencing is a two-way videophone conversation among multiple participants.

Protocols for Video Conferencing

With the advent of Internet, communication formats such as video conferencing and chat etc. have gained popularity.

Here you will learn about some common protocols for video conferencing.

The most common video conferencing protocols are:

  • H.323
  • Session Initiation Protocol (SIP)

Video Conferencing Protocol H.323

H.323 is a standard that specifies the components, protocols and procedures that provide multimedia communication services, real-time audio, video, and data communications, over packet-based networks, including the Internet.

H.323 is part of a family of ITU-T (International Telecommunications Union) recommendations called H.32x that provides multimedia communication services over a variety of networks. These standards define how components that are built in compliance with H.323 set up calls, exchange compressed audio and video, participate in multiunit conferences, and operate with non-H.323 endpoints.

H.323 provides various services, and therefore can be applied in a wide variety of areas, consumer, business, and entertainment applications. It can be applied in a variety of mechanisms given here:

  • audio only (IP telephony)
  • audio and video (video telephony)
  • audio and data
  • audio, video, and data
  • multipoint-multimedia communications

Video Conferencing Protocol SIP

SIP stands for Session Initiation Protocol, is an IP telephony signalling protocol used to establish, modify, and terminate VoIP telephone calls.

SIP works with both IPv4 and IPv6.

For Internet telephone sessions, SIP works as: Callers and callees are identified by SIP addresses. When making a SIP call, a caller first locates the appropriate server and then sends a SIP request. The most common SIP operation is the invitation. Instead of directly reaching the intended callee, a SIP request may be redirected or may trigger a chain of new SIP requests by proxies. Users can register their location(s) with SIP servers. SIP addresses (URL) can be embedded in Web pages and therefore can be integrated as part of powerful implementations such as Click to talk.

SIP can establish, modify, and terminate multimedia sessions such as Internet telephony calls (VoIP or Voice over IP).

SIP can also invite participants to already existing sessions such as multicast conferences. Media can be added to, and removed from, an existing session.

SIP transparently supports name mapping and redirection services, which supports personal mobility.

SIP has taken the VoIP world by storm. The protocol resembles the HTTP protocol, is text based, and very open and flexible. It has therefore largely replaced the H.323 standard.

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