Video conferencing actually encompasses a range of technologies used in a wide range of situations, often it is not just video and audio that is transmitted, but also data, allowing collaborative working though shared applications. All of this means having sufficient bandwidth supporting your network is the critical performance factor.
Video conferencing may be......
* One-to-one meetings, also known as point to point communications, usually involving full two-way audio and video.
* One-to-many involving full audio and video broadcast from the main site, where other sites may be able to send audio. For example in a lecture situation, students could ask questions.
* Many-to-many, known as multi-point communication, provides audio and video between more than two sites. With most multi-point systems only one site in a conference can be seen at time, with switching between sites either controlled manually or voice activated (i.e., the loudest site is on screen).
Physically, the most common scenarios of video conferencing are:
* desktop video conferencing - usually a small camera is located on top of the PC or workstation monitor. The actual video is usually displayed in a small window, and shared applications, such as a shared whiteboard are often used.
* studio-based systems - a studio is specially equipped for video conferencing. This will normally include one or more cameras, microphones, one or more large monitors, and possibly other equipment such as an overhead camera for document viewing. Usually used for more formal meetings
In practice a 'studio' may not be a dedicated room, but a standard seminar room with portable equipment that can be set up when required.
Bandwidth and Compression......
The bandwidth, or baud rate, is the amount of information which can be transmitted every second. The higher the bandwidth, the better quality the signal that can be transmitted. For a video conference audio and video signals must be transmitted in real time, i.e., a lot of information has to be sent every second, requiring a very high bandwidth. For example a 'true colour' image will need 24 bits (3 bytes) per pixel. A full screen image might be 640x480 pixels, over 7 million bits. For full motion video, the image is refreshed 25 times per second. This adds to over 184 million bits per second. It is not realistically possible to transmit this amount of information, and your PC certainly could not receive it at this rate. Therefore for digital video some form of compression is required. The type and degree of compression used varies from system to system. It is interesting to note that for most uses, we are more tolerant of poor video than poor audio, and so some systems concentrate on providing consistently good audio.
How To Get The Right Bandwidth To Meet Your Needs.......
Don't take a chance at guessing what bandwidth you'll need.....or in selecting the provider for that bandwidth. You may need a fractional, full, integrated, or bonded T1, DS3, or OC3 network depending on many factors. Solutions offered by providers will vary by cost, Quality of Service (QoS), and Service Level Agreement (SLA). I strongly recommend you use the services of an independant Telecommunications Consultant to help you assess your needs and find the provider who best meets your requirements. For unbiased free advice....as well as real time rate quotes from multiple providers, indepth research, and negotiations with providers on your behalf....I recommend you use FreedomFire Communications. |
