Live Video Conferencing - Real Time Video Conferencing
Live video streaming requires more resources than streaming archived video files. That makes live video
conferencing or broadcasting more expensive than other types of video streaming.
The main difference between live video streaming and Video On Demand is that a streaming server MUST be used for
live broadcasts or conferences. VOD can sometimes be hosted on a regular HTTP server if the demand for the video is
not too high, but the nature of live video streaming requires the use of a specialized streaming server.
It is true that JAVA applications hosted on HTTP servers can be used for live video, but the video stream is
quite slow compared to using a dedicated streaming server. Think one frame per second for JAVA as opposed to 15 -
25 frames per second for live webcasting or conferencing.
Video streaming requires that the video material be encoded. Encoding compresses the original material and saves
it in a particular streaming format. Encoding for VOD can be done on any desktop computer because it is a non
realtime process. For live webcasts or webconferences, however, encoding must be done on the fly before the video
signal can be sent out over the Internet. This requires the use of a dedicated computer that is connected directly
to the video camera. Encoders can usually accept inputs from several video cameras at the same time.
Because the speed of data transmission is critical, especially for webconferencing, digital video cameras must
be used. There can be no analog to digital conversion process which would delay the webcast signal.
VOD streaming is accomplished by setting up a communication channel between the server and the viewer's
computer. This makes the streaming video accessible to anyone at any time.
Webcasts are different. They are also available to anyone with a computer, but only at one specified time. Since
thousands of people could be watching a webcast, setting up individual data streams between each computer and the
central server could overwhelm the server.
So instead of setting up individual streaming channels, webcasts are transmitted with a protocol known as
multicast. This allows a limited number of video streams to be watched by a potentially unlimited number of
Multicasting can also be used for web conferencing when a large number of participants in various locations are
involved. In this case, each participant is delivering a multicast data stream while receiving several multicast
streams from the other participants. This is a cost effective method of allowing many people in widely separated
locations to participate in a web conference.
Web video conferencing can present new challenges, however, depending on the complexity of the setup. If each
participant is at an individual computer, a simple webcam and microphone is sufficient. However, sometimes web
conferences will consist of several groups of participants, each gathered in a large conference room. This kind of
setup requires more planning and there should be technicians on hand to deal with the details of setting up and
maintaining data connections.