Telecom: Technology Student Papers: Nassar - California Western
Telecom: Technology Student Papers: Nassar

Internet Video Conferencing

by Maximilian Nassar

      Internet video conferencing (IVC) allows communication with crystal clear sound and live video via a computer. This method of communication is unhindered by standard telephone peak/off-peak rates. It creates the possibility of communicating for an unlimited duration at a cost of not much more than standard internet access.

      IVC has been said to be to the mid-1990s what the telephone was to the late 19th century. It is similar to the traditional telephone in that one person dials up another using an appropriate application. The other person then responds to the ring. IVC adds a visual element to the voice conversation. Furthermore, data can be transmitted during the course of the conversation. IVC allows users to see and speak to each other in real time and exchange data simultaneously using a desktop computer "hooked up" to the internet.

      How Does IVC Work? Caller 1 logs-on via a POT (a plain, old telephone line) to the internet site of a particular video conferencing service provider such as CU-SeeMe, VDOPhone or CineVideo, using that service provider's software. A second party, Caller 2, also logs on to the same service provider using the same software. Once both parties are at the server's site, both their names appear at an electronic phone directory. Caller 1 dials up Caller 2 using the server's software; Caller 2 then answers the call.

      With an attached camera and microphone, Caller 1's PC captures the images and sounds of Caller 1 and uses a codec (a compression-decompression algorithm) to prepare the video and voice transmission. The program compresses the recorded image and sound data and divides it into packets for transfer over the internet. Caller 2's PC uses a codec to reassemble and decompress the data for playback.

      Decompression is relatively simple compared to compression, so that the quality of Caller 2's reception will be limited by the ability of Caller 1's codec to compress the data. However, video and audio quality also depends on the type of internet connection. For instance, an internet connection via a relatively fast 28.8-kbps modem will produce mediocre audio-video quality when compared to what a T-1, Ethernet or ISDN connection could produce. (These connections are four or more times faster).

      The sound card determines whether both parties can talk at the same time or not. Full-duplex cards allow for phone-like communication, while half-duplex cards limit the conversation to one direction at a time, like a walkie-talkie.

      Most of the service providers are advertiser-supported. As the parties converse, small advertisements appear on the screen. A user may choose to ignore these ads, or can click on the ad for more information.

      IVC is still in its infancy. Thus, it does have some problems. First, the low frames per second rate (only 2-17 fps compared to 30-34 fps of full-motion video) makes the other party appear to be in slow motion. Furthermore, there is some voice lag since the internet causes a half to one second delay in voice transmissions. (Users of trans-Atlantic satellite telephone services in years past will recognize this lag.) Thus, voice-lip synchronization is faulty. As a result of these "quirks," many IVC users spend a great deal of time during their initial attempts "tweaking" the settings, such as microphone sensitivity, volume, and sampling rates, to achieve optimum results. Until IVC improves, one can take solace in the availability of this technology at trivial costs.

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