An assignment system adapted to accommodate video and audio signals is provided with a digital cross-point switching matrix which is controlled by a control device which enables connections between selected inputs and outputs of said matrix. The input signals are first applied to analog-to-digital converters, from which the signal is converted into serial form before entering the cross-point matrix. The output from the matrix is converted to parallel form and thereafter to an analog signal by digital-to-analog converters. At any one input the color burst information contained on the incoming video signal, is detected and this controls the rate of conversion of the signal into digital form. The horizontal synchronizing pulse information is detected from the incoming signal and is added to the serial data stream in a coded form and after switching of the data is detected and retrieved before reconversion of the data into analogue form.