1. A data processing device for processing a stream of data, comprising: a first memory circuit operable to hold at least a first frame of the stream of data, the first frame of data having a preselected number of data words, the memory circuit connected to an address bus and to a data bus; a port for transferring the stream of data to another device; means for determining a first presentation time for the frame of data; means for determining a first reference time; a processing unit connected to the first memory circuit and to the port; the processing unit operable to transfer the first frame of data to the port, the processing unit being further operable to determine a first time difference between the first presentation time and the first reference time; and means for transferring only a first portion of the first frame in accordance with the first time difference, whereby synchronism between a second presentation time of a second frame of data and a second reference time is improved.