As the power of telecommunications comes into broader use, there is an increasing demand for data security to preserve corporate secrets and the privacy of individuals. Digital encryption has been used as an effective means of satisfying this demand. Achieving encryption for multimedia communications, which includes audiovisual data, requires both the development of high-speed encryption technology and the development of communication processing technology, such as a cipher communication protocol for synchronizing encryption on the transmitting end and decryption on the receiving end. This report discusses technical issues concerning the encryption of multimedia communications and examples of recent developments. CCITT draft recommendation concerning security system for ISDN visual telephones are also described.

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This paper proposes future OA environment featured by "My-Desk" which is a new intelligent terminal, It is an integrated office system for total support by using/delivering the multimedia information and processing office applications. The system is composed of the My-Desk, Service Integrator and Media Integrator, which are connected by LAN (ATM/FDDI) and ISDN. In this paper, we describe the purpose of the new future OA environment, then gives an outline of its functions, constructions and services.

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We introduce the content of teleconference System which based H11 (1.536Mbps) channel provided by ISDN service and developed for the network of Hokkaido Erectric Power Co. Inc. As the definition of H10 connection. 1472Kbps (23B) is allocated to the communication band and we can efficiently use the transmission line by setting both B channel and D channel on ISDN Primary Rate Interface.

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The system which has been announced is the world' s first Desktop all-in-one Video Conferencing system. It includes several functions that are essential elements of video conferencing such as transmission of documents, acoustic echo cancelation, adjustable lip-syncronization control, and the system controling console. This paper describes the development of the Video Conferencing system - the DP-200 and the CA-200 with these functions. With this development, a new concept of multi-media AV communication has been realized.

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In the field of the CCITT activity, it was agreed to use Multi Layer Protocol (MLP) path on H.221 frame for multipoint control in future teleconferencing systems. This paper first explains about CCITT Draft Rec. T.122 which defines Mulitipoint Communication Service (MCS) using MLP path. Next we propose how to apply MCS to multipoint video conference. We pick up some elements from MCS and show a sequence to open a multipoint video conference using these elements. We also studied the difference of delay between using MLP path and using MLP path, including multiple MCUs. As a result, we show MCS and MLP path are useful enough for multipoint control.

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A multiwindow system has drawbacks in window operability especially when it is used in a multimedia teleconference system, which simultaneously displays many windows like participants facial images, data, or documents. We, therefore, proposed a window auto-management system to reduce tedious window operations. To realize truly usable and natural auto-interface, we established the rules on how to layout overlapped windows based upon experiments and observations. The rule, discussed herin, is about how much portion of a window is allowed to be overlapped (minimum expose ratio), depending upon the overlapping position, the size of the window, and media.

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In this paper, a quality enhancement method is proposed for efficient coding of video in teleconference systems. The method precisely encodes the talker's face area without increasing average encoded bit rate. To specify the talker's face, delay value is calculated from stereophonic speeches by estimating cross-channel transfer function. Computer simulation results showed that the quality enhancement was well controlled by dynamically tracking the talker's face location using stereophonic speeches.

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Many applications on neural networks have been proposed and effectiveness on applications l have been reported. Particularly in the pattern recognition problem, networks offerd effective mechanism and this applications are used frequently. In this paper, we propose an application to classification of remote sensing data. Pattern recognition problem and classification problem resemble each other and are confusedly understood. In the classification problem, all patterns must be divided to some classes prepared before processing, while in the pattern recognition problem, a pattern attributes a class or does not attribute any class. In the classification of remote sensing data. patterns observed by LANDSAT satellite sensor are divided to all classes. Therefore, if we don't prepare sufficient classes or remote sensing data is influenced by any element, misclassification will occur. We introduce an application of neural networks to remote sensing data and discuss some weak points in this application.

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