Patent ID: 7519275

Claim:
A reproducing apparatus comprising: a reading unit arranged to: read main data recorded in a bitstream, the main data comprising audio data and/or video data; read sub data, corresponding to the main data, recorded in a bitstream that is separate from the bitstream of the main data; read navigation information recorded in a bitstream that is separate from the bitstream of the main data and the bitstream of the sub data, the navigation information defining a relation between the main data and the sub data that enables the sub data to be reproduced in synchronization with the main data; and a mixer arranged to mix the main data and the sub data read by the reading unit based on the navigation information read by the reading unit to obtain mixed main data and sub data; wherein: the navigation information comprises: identifiers for the main data; and playback time information for the sub data; and the main data, the sub data, and the navigation information are asynchronously recorded.