Abstract: An arrangement for decoding and deciphering signals having been subjected to an encoding of the MAC type and to an enciphering by cyclic permutation at one point of cut, i.e. by cyclic permutation of the assembly of the chrominance and luminance signals C and Y, respectively, from an abscissa a situated in the chrominance signal, by using a sampling frequency f.sub.o, or at two points of cut, i.e. by cyclic permutation independent of the chrominance and luminance signals C and Y, respectively, from abscissa a.sub.c and a.sub.y, respectively, by using a sampling frequency f.sub.o, especially characterized in that upon reception a sampling frequency f.sub.r is used different from f.sub.o and connected with the latter by the relation ##EQU1## p and q being integers, and in that the new address (es) of the point(s) of cut is (are) chosen equal in the first case to the integral value closest to the result a' of the operation, ##EQU2## and in the second case to the integral values closest to the results a'.sub.

Abstract: Television system in which the digital data, the chrominance signals and the luminance signals are time-division multiplexed. This system, adapted for transmitting pictures having an aspect ratio of approximately 5/3, is such that the compatibility with receivers capable of receiving and processing the signal in accordance with the MAC system with an aspect ratio of 4/3 is ensured without any change in the instantaneous digital flow rate, nor in the compression factor of the video signals. In addition, the horizontal extension of the picture to the aspect ratio 5/3 is obtained by reducing the length of the data burst preceding the video signals and by suppressing a certain number of video lines located at top and/or at bottom of the picture, in order to make it possible to place the data suppression in the bursts in the position of these video lines and within a certain number of previously non-utilized line periods during the field retrace.