A local storage (200) contains PlayList inforamtion. The PlayList information includes main path information and sub path information. The sub path information specifies one of AV Clips as a sub clip and defines a reproduction section as a slave to be synchronized with a reproduction section as a master for the sub clip. The local storage (200) contains an audio stream specified as the sub clip. The audio stream is formed by a plurality of PES packets. Each of the PES packets has a packet identifier (PID). The packet identifier has an upper-node field and a lower-node field. The upper-node field indicates that the audio stream formed by the packet is a secondary audio stream and its audio output is mixed with the audio output of a primary audio stream.