The invention relates to a device for coding video data comprising means to code a video stream as groups of pictures, each group of pictures comprising at least one description unit relevant to the coding of the said group of pictures. According to the invention, the coding device comprises means to insert in the stream of data at least one message indicating whether the description unit of the current group of pictures is identical to the description unit relevant to the preceding group of pictures. The invention also relates to a device for decoding video data comprising means to decode a stream of data coded with a device according to one of the preceding claims. According to the invention, the decoding device comprises means to analyse the said messages, means to decode the at least one next description unit if the said message indicates that this unit is different from the preceding description unit, otherwise, if it is identical, not to decode it.