A data stream (DS) comprises a time multiplex of coded data (D) and control data (C). The data stream (DS) may be, for example, of the MPEG type representing a sequence of pictures. The coded data (D) is transcoded (T) so as to obtain transcoded data (DT) which differs in size from the coded data (D). The control data (C) is adapted for the transcoded data (DT) so as to obtain adapted control data (CA) which does not substantially differ in size from the control data (C). The transcoded data (DT) and the adapted control data (CA) are written into a transcoder output buffer (TOB) and read from the transcoder output buffer (TOB) so as to obtain a transcoded data stream (DST). This allows an efficient use of a transmission channel via which the transcoded data stream (DST) is to be transmitted and, consequently, it allows a satisfactory transcoding quality. A size adjustment of the transcoded data (DT) on the basis of the amount of data contained in the transcoder output buffer (TOB) and control codes (CC) contained in the data stream (DS) further contributes to a satisfactory transcoding quality.