Abstract: A video codec for a videophone terminal of an integrated services digital network. The codec is organized to receive firstly image signals from a television camera so as to transmit them, after compressing and encoding them, to a remote video decoding unit, via a digital transmission line, and secondly similarly-processed image signals via the digital transmission line, so as to decompress and decode them for a television screen receiver locally connected to the video codec. The video codec includes a processing unit, of the integrated circuit type, co-operating with a single external memory plane both to compress and encode data to be transmitted, and also to decompress and decode received data, with the assistance of internal operational components time shared so as to apply known methods to transmission and to reception.

Abstract: The invention relates to the coding of analog signals. An analog signal is compared with a comparison signal increasing according to a given law, until equality with the analog signal is reached; then, the comparison signal remains constant during a predetermined time and resumes its original value. The transmission device includes a processing circuit at the transmission end and at the receiving end; at the transmission end, the processing circuit is preceded by a comparator receiving the analog signal, and the comparison signal supplied by a converter is fed thereto by the processing circuit; at the receiving end, the signal to be decoded is supplied to a forming circuit connected to the input of the processing circuit. The present invention is applicable to data transmission and to telephony in particular.