Picturetel Corporation

Louis J Kerofsky

Qin-Fan Zhu

A multipoint control unit (MCU) includes a plurality of segment processors arranged to extract segment data from a corresponding plurality of input video streams and a plurality of data queues, each one of the data queues being coupled to a corresponding one of the plurality of segment processors for storing segment data provided from the segment processors. The (MCU) also includes a data combiner coupled to the data queues for combining output data from the data queues and a controller coupled to the combiner for selectively providing data to the combiner in accordance with the amount of the data in the data queues. Several different approaches for determining what queues to obtain data from are described to reduce insertion delay Asymmetric picture rates are also used to reduce the video mixing delay. In addition, the multipoint control unit can optionally have the segment processors including a rate reducer and have the combiner controller send bit rate control information to the reducer to control the operation of the reducer.

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Acton, MA, United States of America

Louis J Kerofsky