Abstract In the transmission of image sequences over an ATM network variable bit-rate coding techniques can be implemented to optimize performances and to improve channel sharing efficiency. On the other hand the use in ATM networks of a packet switching technique introduces some problems related to packet delay, cell loss and packet delay jitter. One possible solution to these problems is the transmission of the video information over the network with different levels of protection with respect to the packet losses. The information used to guarantee a video connection with minimum acceptable quality is transmitted in a very protected way. On the contrary, the other information necessary to increase the quality of the coded images up to the desired level is not intrinsically protected against data loss. In the paper two different realizations of this type of video coder are presented and their performances are compared.