Abstract: The useful signal of a sampled video line is, at least partially, spliced to two adjacent segments (AB, BC), each of which has at least two states. The splicing point (B) between the two segments is synchronously defined in a pseudo-random manner at transmission and reception. Upon transmission, at each line and in a pseudo-random manner, one of two possible scrambling schemes is selected. The first scheme involves local reversing of the second segment, and the second scheme involves a reversing of the second segment followed by a permutation with the first segment. Upon reception, the processing is the inverse of the processing which occurred at transmission and is applied in order to reintroduce intelligibility to the video signal. That is the locally reversed segments are received and reversed, following the permutation used at transmission. The process applies to a MAC signal.