An apparatus for use in a packet-based communication system, comprises an input and an output. The apparatus is configured to receive a stream of data packets, having an inter-packet spacing, and store the received data packets and information representing the inter-packet spacing in a buffer, wherein the data packets are no longer than a common maximum data-packet length. The apparatus is further configured to schedule, at intervals, all the contents of the buffer except for a constant amount, into a respective container of a sequence of containers and, if the container then contains an incomplete data packet, schedule the remainder of the incomplete packet into the container. The apparatus is further configured to send the sequence of containers, wherein the positions of the data packets within the containers depend on the received inter-packet spacing, and wherein the constant amount is equal to or greater than the common maximum data-packet length.