Video Conferencing : SIP Protocol
Web cam chat conferencing, previously known as videoconferencing, brings people together at different locations by using the interface between audio and video. This can involve a point-to-point conversation between two people; or it can involve multi-point conversations between large groups at several locations. Not only can video web cam conferencing be used to share computer-displayed information, documents and whiteboards, it also uses audio and visual mediums to transmit meeting activities.
In the 1980s, digital telephony transmission networks assured a minimum bit rate for compressed video and audio transmission. As networks started to expand throughout the world, the first dedicated systems started to appear on the market. This evolution continued throughout the 1990s, when video teleconference systems went from being very expensive, privately held equipment, network requirements and software to technology available to the general public at an affordable cost.
During the 1990s, Internet Protocol (IP) based videoconferencing became a reality and more efficient video compression technologies were developed. That permitted personal computer-based videoconferencing and allowed for the arrival of web cam chat for almost everyone. Free services, webcam software and web plug-ins like NetMeeting, MSN Messenger, Skype, Yahoo Messenger and others brought cheap conferencing to the masses.
Multipoint conferencing is more complex
Multipoint conferencing is more complicated because it has to coordinate several different locations simultaneously. Since you can’t be in direct contact with several places at once while they are all in contact with others, you need one source that will tie them all together. In video conferencing, this is called a multipoint bridge or multipoint conferencing unit (MCU).
An MCU enables multi-location video conferencing by providing a sort of “central processing center” for all of the locations through which all the information flows. The MCU receives all information from the various locations and then sends it out to each location. In some cases the MCU is located on a particular PC, and in other cases it is located on a remote server (the most common structure, particularly for more powerful MCU networks).
Audio is usually sent and received simultaneously in all locations with an MCU with no problem because of the relatively small bandwidth needed for transmittal. It is broadcast in what is called “full duplex” mode, meaning everyone can talk and hear at the same time with no cutting off when one person or another speaks.
Video transmission, however, can be broadcast in a number of ways with an MCU depending upon the quality of the software and the complexity of the system. Some common types of video transmission for video conferencing include:
- Continuous Presence video conferencing, which allows up to four conference sites to be seen simultaneously on split screens. This is usually used if you have a small group or individuals in separate locations and will primarily be seeing close-up shots.
- Universal Control video conferencing is controlled by the initiating conference site. The primary site determines who sees what at all other sites.
- Voice Activated video conferencing is by far the most common type used today. The image with these systems shifts to the site that is currently activating the microphone so that you can always see whoever is speaking. However, if there is a good deal of background noise participants should mute their microphones when they aren’t talking in order to avoid the image jumping about needlessly.
Further, it should be able to house at least 20 to 30 at a time and meet the space requirements as set by the Association of Conferencing centers. As for the hardware requirements, there should be at least two or three large size LCD televisions or high definition televisions to enhance the conferencing process. There should at least be 5 to 6 telephone line for conversation and for providing connectivity for the conference to take place.
Overcoming firewall issues
There are, of course, obstacles to overcome when you take a look at how video conferencing works. After all, you’re sending vast amounts of translated data either directly or through a gatekeeper system (the MCU) that is switching and transferring information between a variety of computers. Just about any business these days has a firewall system to provide security and protect the system from potential viruses. Trouble is, many firewalls also block the transmission of data for video conferencing.
Recent innovations have largely circumvented these problems by designing firewall solutions that recognize video conferencing signaling requests and allow the information packets to bypass the firewall or router without disabling the firewall protection for other traffic. Even with this, however, there may be occasions when packets are dropped because of heavy traffic on the system, so investing in a firewall system that can handle substantial traffic is essential to quality video conferencing performance
Resource Author Francisco R. Higueras
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