Abstract: Provided is a terminal unit that, even in case video image is suspended by a handover, video reproduction is possible real-time at immediately after an end of the handover. In a video transmission system comprising a wireless LAN accommodated switch for switching over the connection relationship of a terminal unit and an access point, an access point for receiving video data sent from a terminal unit and sending it to another terminal unit, and a terminal unit for receiving video data sent from the access point thereby displaying a video image and carrying out an association establishment or release of a wireless channel to an access point, the terminal unit operates such that, when a calling party releases a wireless channel, the opposite terminal unit determines that the calling party has started a handover and makes an operation to change a video data encoding into an intra-frame encoding.

Abstract: Provided is a server apparatus and terminal unit for realizing a video transmission system that, even in case the video image is suspended by a handover, reproduction can be resumed at a video image of upon suspension. In a video transmission system having a video server for sending video data to a terminal unit through an access point and a terminal unit for receiving and displaying the video data sent from the access point and for establishing an association and releasing of a wireless channel to the access point, the terminal unit releases the access point and wireless channel and requests the video server to suspend the transmission and store video data. In case an association is established with a new access point, the terminal unit requests the video server to re-send the video data, etc. stored in the duration of from the release to an association establishment.

Abstract: The invention provides a television meeting unit that is capable of displaying a picture smoothly on a middle participation terminal. To realize such television meeting unit, the multicast meeting unit is provided with a picture coding means for coding an input picture, a picture transmission means for transmitting the coded picture by mean of multicast, a picture receiving means for receiving the transmitted coded picture, a picture decoding means for decoding the received picture, a picture display means for displaying the decoded picture, a middle participation notice means for notifying middle participation in a meeting, and a middle participation terminal detection means for detecting the middle participation notice and for transmitting it to the picture coding means. The picture coding means, upon receiving the middle participation notice from the middle participation terminal detection means, changes the coding format to the in-frame coding format.

Abstract: The invention provides a television meeting unit that is capable of displaying a picture smoothly on a middle participation terminal. To realize such television meeting unit, the multicast meeting unit is provided with a picture coding means for coding an input picture, a picture transmission means for transmitting the coded picture by mean of multicast, a picture receiving means for receiving the transmitted coded picture, a picture decoding means for decoding the received picture, a picture display means for displaying the decoded picture, a middle participation notice means for notifying middle participation in a meeting, and a middle participation terminal detection means for detecting the middle participation notice and for transmitting it to the picture coding means. The picture coding means, upon receiving the middle participation notice from the middle participation terminal detection means, changes the coding format to the in-frame coding format.

Abstract: A conference terminal is incorporated in a multicast conferencing system. The conference terminal receives a request for division into groups. The request includes information indicating that the terminal belongs to which group. The terminal then produces, in response to the request, only the stream data coming from one or more other conference terminals belonging to the same group as the terminal. This production is realized by selectively accepting such stream data at a reception unit to which all stream data are transmitted from all the terminals having the same multicast address. Alternatively, the production is realized by selectively re-writing stream data at a scene re-writer. Thus, the produced stream data are replayed and displayed. The division of an entire group into plural small groups can be performed without additionally issuing multicast addresses.