A new interframe coding system with an adaptive vector quantizer which is controlled by the movement detecting parameters is presented and simulated. This interframe coding system consists of the specific function units ; the interframe DPCM coder by k= m×n lattice samples, the movement detector, the conditional replenishment frame memory, the adaptive vector quantizer, the variable length coder and the transmission buffer. In this system the bit rate of video signals is reduced by means of vector quantizing the movement area block by block. The coding performance has been given for the overall movement area ratio about 30% with the overall S_<p-p>/N_<rms> ratio about 37.2 dB at 0.4 bit/pel/frame. The good picture quality for teleconferencing use is provided.
Reservation based Communication is indispensable for video teleconferencing. For this communication, 5 functions are needed. They are sending/receiving reservation information from/to reservation terminals. reservation accepting control function, resource assigning function, file managing function and connection control function for broadband communication lines. In the experimental Broadband Communication System, Reservation based Communication Controller (RCC) performs the above mentioned functions, except for the connection control function, which Broadband Switching System (BS) performs. Reservation information is transmitted between RCC and customer's reservation terminals via the telephone network. Pushbutton telephone sets and Display Phone are adopted for reservation terminals. The connection control function is transmitted from RCC to BS via the electrical bus. Seven reservation accepting services are provided. They are new communication call reservation, reservation modification, reservation reference, etc. RCC is controlled with function shared 16-bit processor modules, so that the addition and modification of service specification can be dealt with easily. Reservation based communication control software is written is C language. Meetings held via video teleconferencing can be held punctually on schedule without block.