Point-to-Point vs. Multipoint Web Videoconferencing

Web videoconferencing is a popular and convenient technology that enables people in remote locations to come together in face-to-face, voice-to-voice meetings without the challenges of travel. Physical materials and presentations are shared just as if the meeting’s participants were in the same room. As bandwidth availability continues to grow and the costs related to videoconferencing continue to shrink, the choice to meet via streaming live video becomes more prevalent.

At base, there are two different types of videoconferencing: point-to-point and multipoint. The difference is in the logistics or number of locations participating in the meeting. The simplest configuration is the point-to-point videoconference. Two locations are simultaneously connected over the Internet. Given enough bandwidth, participants can exchange audio and visual content in real time. Each location may have one or more people present, but each location is considered one point on the network.

A multipoint videoconference is more complex. In this case, more than two locations are simultaneously connected over the Internet with the ability to exchange audio and visual content in real time. The complexity with multipoint videoconferencing is twofold. More bandwidth is required and you need to decide what type of videoconferencing session you want to have.

Most multipoint videoconference data is exchanged and managed with a bridge or multipoint control unit (MCU). An MCU is usually built into the videoconferencing software or application and makes for smoother audio and video streaming.

The management of audio and video streaming can be either centralized at the host location or decentralized, in which case each location engages in a direct exchange of audio and visual content. The benefit of decentralization is generally the delivery of higher quality content. This arrangement with no control point managing or relaying the content is also known as an ad-hoc connection and is the most popular choice.

Another decision to be made with a multipoint videoconference is whether to use continuous presence (CP) or voice-activated switching (VAS) mode for the pickup and delivery of streaming content. With CP mode, all locations are seen and heard simultaneously. The video is represented in a split-screen format so that each location sees all the other locations presented in a grid-type framework on a single screen or monitor.

With VAS mode, all locations see only the location of the speaker, and the view changes as the speaker changes. The functionality of VAS moves the video pickup to the location from which audio emanates. This switching can be ideal for presentations of detailed data in which a larger visual is important rather than the compressed visual in the split-screen of CP mode.

In a nutshell, if you have more than two locations participating in your virtual meeting, you will be engaging in a multipoint videoconference. On the other hand, you may be familiar with the point-to-point version if you’ve used the audio and video features of Skype, for example, to call your cousin in Karachi.

© Julie Pierce and Julie’s Portfolio, 2005-2013.

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