A multipoint control unit (MCU) is a type of video conferencing hardware that bridges terminals involved into a multi-point conference system.
MCU makes it possible for a multipoint audio/video conference to be controlled and moderated from a single location. Multi-stream audio/video conferencing is bandwidth-intensive, easily requiring up to 6 Gbps, depending on the number of members. The units gather bandwidth data for all connected points and then adjust quality so that all points are capable of good performance. MCU are connected near the WAN, often contained in a rack server configuration.
MCU allow a user control different modes of displaying conferenced terminals. Modes include:
- All individuals displayed on a split screen.
- Voice-activated selection of displayed speakers.
- Individual conference points displayed full screen and switched between manually by a human moderator.
See an introduction to Cisco's MCU: