Virtual Conferencing Glossary

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MAC (Media Access Control) - A system of rules used to move data from one physical medium to another.

MBONE (Multicast / Multimedia Backbone) - A collection of Internet routers that support IP multi-casting. The MBONE is used as a "broadcast" channel on which various public and private audio and video programs are sent.

Mbps - Megabits per second or approximately one million bits per second.

MCU (Multipoint Control Unit) - Videoconferencing equipment that allows more than three individual videoconference units to connect together to form a multiparty videoconference session. The MCU uses fast switching techniques to patch the presenters or speaker's input to the output ports representing the other participants.

MLP (Multi-layer Protocol) - for data in H.221. MLP data and audio can only be placed in the first 64Kbps channel of a connection. T.120 must use the MLP or HMLP channel.

Modem - A device used to transmit digital data across analog telephone circuits.

Modulator - A device which modulates a carrier. Modulators are found as components in broadcasting transmitters and in videoconference transponders.

Modulation - The process of manipulating the frequency or amplitude of a carrier in relation to an incoming video, voice or data signal.

MPEG - Moving Picture Experts Group. Generally used to refer to coding standards for video images sent over INTERNET. MPEG coding is a common standard for which a number of public domain players exist.

Multicast - An Internet technology for transmitting data simultaneously to many receivers without the need to replicate the data.

Multicasting - Conferencing applications that typically use packet-switched transmission to broadcast a signal that can be received by multiple recipients, all of whom are listening on a single multicasting address.

Multimedia - Multimedia is more than one concurrent presentation medium (for example, on CD-ROM or a Web site). Al-though still images are a different medium than text, multimedia is typically used to mean the combination of text, sound, and/or motion video. Multimedia can arguably be distinguished from traditional motion pictures or movies both by the scale of the production (multimedia is usually smaller and less expensive) and by the possibility of audience interactivity or involvement (in which case, it is usually called interactive multimedia). Interactive elements can include: voice command, mouse manipulation, text entry, touch screen, video cap-ture of the user, or live participation (in live presentations).

Multiplexer - Electronic device that divides the bandwidth of a channel by frequency or time to enable multiple devices to share the channel.

Multiplexing - In data transmission, a function that permits two or more data sources to share a common transmission me-dium with each data source having its own channel. The process of combing multiple signals onto a single circuit using various means.

Multipoint - Communication configuration in which several terminals or stations are connected. Compare to point-to-point, where communication is between two stations only.

MVIP - Multiple Vendor Integration Protocol. A set of standards which include a digital telephony bus, a telephone switching capability, and the software conventions needed for an integrated system. The bus is designed to connect cards within a PC using a forty-pin ribbon cable. The bus consists of 16 serial operating at 2.048 Mbps each, that is 32, 64 kbps channel each.