Abstract: To be able to transmit television pictures in a digital format on a medium having a limited bandwidth, the picture are subjected to a coding operation and thereby converted into a series of transmission bit blocks TRB.sub.n of variable length (for example DCT and variable length coding). Each transmission bit block is divided into a main block H.sub.n having at least the most important code words and an auxiliary block S.sub.n comprising the other code words. By carrying out a formatting operation, a group of transmission bit blocks is converted into a channel bit block consisting of a number of sub-channel bit blocks SCB.sub.n of equal length. The main blocks are accommodated at the first bit positions of the sub-channel bit blocks and the bits of the auxiliary blocks are spread over the remaining bit positions. It is thereby achieved that the most important information is always found at fixed locations so that the influence of sync losses is reduced considerably.