A DVD transport stream including a video and a sub-picture stream shall be transcoded to a broadcasting transport stream. For this a decoding-encoding-chain merging video and sub-picture into a single video bitstream to conserve the information of the sub-pictures although not in the broadcasting format reserved is provided. By performing a sub-picture macroblock analysis the transcoding can be controlled such that the motion estimation unit of a standard MPEG-2 encoder and/or the entire decoding loop within the encoder can be saved.