Information storage medium, TS packet judgment apparatus, and data reproduction apparatus

The present invention provides an information storage medium in which a stream including basic data and extension data for next generation is stored, so as to allow a decoder capable of decoding only basic data to process such a stream including basic data and extension data. Such information storage medium is an information storage medium on which an audio stream including a plurality of TS packets is stored, wherein each of the TS packets includes one of (a) a first packet including basic data, and (b) a second packet including extension data related to the basic data, the basic data is data capable of being decoded into complete sound without requiring the extension data, and the extension data is data intended for improving the quality of audio generated from the basic data, and a header of each of the TS packets includes an identifier indicating whether the TS packet includes the first packet or the second packet.