In the DVR or Blu-ray application format, a clip consists of a clip information file, through which it can be accessed from playlists, and an audio-visual data stream file. The data stream includes data units, which in turn include multiple source packets. When such stream shall be split between source packets into two substreams, and the splitting position is within such a data unit, the employed file system may not allow splitting single data units. According to the invention, the smallest possible data unit that includes the intended splitting position is declared as a separate tile, having separate clip information and data stream files. The first and second substreams are accessible via one or more RealPlaylists and/or VirtualPlaylists. The first substream comprises data from the first and second clips, and the second substream comprises data from the second and third clips.