Hitachi, Ltd.

Taizo Kinoshita

Satoshi Tanaka

Minoru Nagata

Nobuo Kotera

Hirotoshi Tanaka

Koichi Shibata

Atsushi Saito

Kiichi Yamashita

Yoshitaka Takasaki

Katsumi Tada

Mitsuru Ikezawa

Shigeki Kitajima

Itaru Mimura

Hirotada Ueda

Junichi Kimura

Masahiro Kageyama

Toshiaki Suzuki

Tomoyuki Watanabe

Yoshizumi Eto

Hiroshi Yoshigi

Akira Date

Shigeo Sumino

Toru Matsushita

Hisao Tanabe

Tatsundo Suzuki

Yukio Kumagai

Akihiko Ohba

Tomoko Nakahashi

Fumio Noda

The video information recording and reproducing apparatus includes an inputting information part for receiving video information, a storing information part, an outputting information part for producing video information, an automatic indexing information part for automatically adding indexes to the inputted video information, a filtering video information part for automatically selecting video information to be stored from the inputting information part, and a controlling part for controlling the above elements, thereby actualizing the free time-shift viewing function, intelligent search function, and automatic video data base generation function.

Video information recording and reproducing apparatus

In a digital data transmission system of the present invention, the total transmission rate which changes with the passage of time in a plurality of video/audio signals multiplexed with a plurality of digital data on a transmission path is monitored without allocation of individual transmission rates to the plurality of video/audio signals so that encoders are controlled only when the total transmission rate exceeds the maximum transmission rate. Further, the plurality of digital data are transmitted within a range of the residual transmission rate obtained by subtracting the total transmission rate of the plurality of video/audio signals from the maximum transmission rate in the transmission path, whereby real-time transmission of video/audio signals and transmission of digital data can be made consistent with each other on one transmission path without reduction in video/audio quality of the transmitted video/audio signals.

Digital data transmission system

A method and system for information processing in a bidirectional information transmission system, particularly for transmitting information in accordance with a change in a transmission capacity of a transmission line. A system is provided which can change an information transmission rate in accordance with a room capacity of a transmission line. This information transmission system includes a plurality of information providers, a plurality of information receivers, an information storage and distribution unit connected to the information providers and receivers, and a plurality of information transmission lines for information transmission between the information providers and receivers and the information storage and distribution unit, wherein the information transmission rate of each information transmission line is changed.

Information transmission system with variable transmission rate

A multi-point video conference system includes a plurality of terminals and a network. Each terminal includes a coder to code and to packetize at least a motion picture in a block unit and a multi-point video decoder to sequentially receive and to decode packets sent from decoders at other points. The decoder includes a video processor to process video information in a time sharing manner, a channel selection controller to decide a transmission source of a received packet according to information of the packet and to notify the source to the video processor, a shared frame memory to store therein video information from the plural terminals, and a display frame memory to output therefrom the video information in a synchronous fashion.

Multi-point motion picture encoding and decoding apparatus

An image encoding apparatus, image decoding apparatus, or image encoding and decoding apparatus having a circuit for dividing a screen into sub-areas to conduct an encoding or decoding operation for each sub-area includes an image dividing circuit for dividing an input image into sub-areas each having a predetermined contour, sub-encoders for encoding the sub-areas respectively related thereto, a code integrating circuit for integrating the codes of the respective sub-areas, and a shared memory for storing images locally decoded by the sub-encoders.

Image encoding and decoding apparatus

A multi-point visual communication system which includes an adaptive filter part for controlling a spatial frequency characteristic of a video signal, a filter selector for selecting a video quality to be transmitted from its own site on the basis of integrated requests received from sites, and a filter control for adaptively controlling a filter characteristic taking both of a video information quantity and situations of a telecommunication network into consideration, and wherein a video signal processed by the adaptive filter part is subjected to an encoding operation and then transmitted to the telecommunication network. Thereby, the video quality can be selected according to users' requests, and the video quality of the multi-point visual communication can be improved without incurring an excessive increase of a video information quantity. Further, through the video signal processing taking both the video characteristic and the telecommunication network situations into consideration, a comparatively high quality of video transmission can be realized when viewed from an information quantity.

Multi-point visual communication system

A system and a user interface make it possible to easily edit important items of a program, such as a conference, in a short time using multimedia information. A retrieving file is generated by extracting a keyword from multimedia information input through a dynamic image input unit such as a camera, a voice input unit such as a microphone, a handwritten character input unit, a pointing unit such as a mouse, and a key-input unit such as a keyboard. A report preparation supporting system and a user interface make it possible to easily edit a report in a short time by referring to the retrieving file and retrieving and editing a scene in which an important item appears when the report is prepared.

Conference multimedia summary support system and method

A display system for displaying a plurality of video windows on a display screen. A receiving element is included for receiving video data packets from a plurality of video sources in a time sharing manner, each of the video data packets including: coded video information for representing a partial image contained within one of a plurality of blocks constituting a video frame; attribute information for indicating at least a location of a block corresponding thereto within the video frame; and identification information of the video source. A decoder element is connected to the receiving element for decoding the coded video information extracted from each of the video data packets and for outputting a partial image corresponding to one of the blocks in the video frame. A set of frame memories are included for assembling partial images into video frames, each of the frame memories having a plurality of window areas located in a predetermined layout defined therein, and a set of the window areas each located at a same location within respective frame memories being associated with a same video source with respect to each other. A writing element is included for writing each partial image derived from the decoder element into one of the window areas within one of the frame memories which is specified in accordance with the identification information extracted from a video data packet related to the partial image and a utilization status of the window areas. Finally, an outputting element is included for selectively outputting contents of the frame memories on a display screen by changing over the frame memories depending upon a display position on the display screen thereby to present a plurality of video frames at a plurality of window areas on the display screen.

A real time visual communication system capable of improving a correspondence between a received video signal and a received audio signal in real time and improving reality. An AV signal is separated into a video signal and an audio signal, and the output state of the video or audio signal is controlled by the characteristics of the audio or video signal. For example, the sound field, reverberation, and the like are controlled in accordance with the characteristics of the video signal. A suitable image pickup unit is selected in accordance with the characteristics of the audio signal to make the sights of conversation participants coincide with each other. It is possible to reproduce sounds of audio signals well matching video signals and to provide visual communication having good reality because of the combination of matched audio and video signals.

Apparatus for integrally controlling audio and video signals in real

Multi-point video conference system wherein each terminal comprises a

A variable length image coding system for multiplexing multi channel parallel data at a specified speed after making variable length coding, and capable of suppressing the variation of amount of code generated upon multiplexing to within a specified range. In order that the total output of the sub-buffer memories is suppressed to within a certain range, the bit calculator calculates the amounts of code generated from the coders of each of the variable length coder sets, selects suitable ones of the coders for the respective channels, and controls the selectors, the output time zones of data from the sub-buffer memories, and the multiplexer. The coder buffer memory reads data in synchronism with the transmission speed and controls the variable length coder sets by feedback or stops the output of data by supplying a dummy in order to prevent the overflow and underflow. Since the amount of code for each n blocks is limited, the freedom of the assignment of amount of code to each block can be increased as compared with the case of single-block unit processing.

Variable length image coding system

A video signal transmitting method comprising: a sending method including the steps of: dividing an analog video signal in a unit corresponding to integer times of a number of bits composing an information field of one packet in packet transmission and converting into a digital video signal, forming a digitalized video signal into a plurality of packets, forming a plurality of packets into a first packet block in M lines.times.N columns, adding an error correction code which corrects a longitudinal error of data in a first packet block as a second packet block in P lines.times.N columns in an (M+1)th line and thereafter, and sending a packet; and a receiving method including the steps of: recomposing the same packet block as that composed on a sending side from plurality of received packets, recovering a video signal with packet loss information from an exchange and an error correction code formed into a packet, and regenerating an analog video signal from a digital video signal after recovery.

Video signal transmitting method and equipment of the same

A wide-band and high-gain differential amplifier adapted to amplifying transmitted optical signals of the GHz band is constituted by GaAs MESFET's. Two MESFET's Q1 and Q2 are differentially connected to each other. Drains of Q1 and Q2 are connected to load resistances R.sub.L and R.sub.L via a source-drain path of other MESFET's Q3 and Q4 whose gates are grounded in AC-wise. Current by-passing means 4, 4 are connected to the sources of other MESFET's Q3, Q4. DC bias currents of the differential pair of MESFET's Q1, Q2 are set to relatively large values to increase the mutual conductance gm of the differential pair of MESFET's Q1, Q2. Despite a large DC bias current, the current by-passing means 4, 4 decrease the DC voltage drops across the load resistances R.sub.L, R.sub.L, and enable the differntial amplifier to operate on a low power source voltage.

Amplifying circuit

This invention relates to a threshold voltage detection circuit for detecting the threshold voltage of field effect transistors (FETs) and to a semiconductor circuit capable of a stable operation irrespective of the fluctuation of the threshold voltage by utilizing this threshold voltage detection circuit. The source-drain path of first FET is connected in series with that of second FET having substantially the same threshold voltage as that of the first FET and the conductances of these first and second FETs are set to a predetermined ratio to generate a voltage drop associated with the threshold voltage in the first FET. This voltage drop can be used for detecting the threshold voltage and for level-shifting. The output of the series connection of the first and second FETs is applied to the gate of a constant current FET having the same threshold voltage as that of the first and second FETs and the drain current of the constant current FET can thus be set irrespective of the fluctuation of the threshold voltage.

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Musashimurayama, Japan

Taizo Kinoshita