A multiplexer configured to multiplex audio data as TS (Transport Stream) packets of the same transport stream, comprising: first encoding means configured to encode said audio data using a first encoding method serving as a predetermined encoding method; second encoding means configured to encode said audio data using a second encoding method, which is a variable-length encoding method, and also differs from said first encoding method, arranged to add a timing value representing timing employed for a case of being decoded to each predetermined audio data unit; PES packetizing means configured to packetize said audio data encoded by said first encoding means, and said audio data encoded by said second encoding means to PES packets, and also add point-in-time information employed for a case of being decoded to a plurality of said packetized PES packets; TS packetizing means configured to packetize said PES packets PES-packetized by said PES packetizing means to TS packets, and also add the same ID to a plurality of said packetized TS packets including a TS packet comprising audio data encoded by said first encoding method and a TS packet comprising audio data encoded by said second encoding method, add identification information for identifying audio data encoded according to the first encoding method to TS packets comprising audio data encoded by said first encoding method, and add identification information for identifying audio data encoded according to the second encoding method to TS packets comprising audio data encoded by said second encoding method; determining means configured to determine TS packets to be multiplexed from a plurality of said TS packets packetized by said TS packetizing means; and multiplexing means configured to multiplex said TS packets determined by said determining means; wherein said PES packetizing means is configured to packetize said audio data encoded by said first encoding means, and said audio data encoded by said second encoding means to PES packets such that said audio data unit satisfying a predetermined cycle appears at the head of a PES payload; and wherein said determining means is configured to assume a first virtual decoder configured to decode said audio data encoded by said first encoding means, and a second virtual decoder configured to decode said audio data encoded by said second encoding means based on said timing value added to said audio data encoded by said second encoding means, and also to determine TS packets to be multiplexed based on multiplexing constraints arranged to randomly access said multiplexed TS packets. first encoding means configured to encode said audio data using a first encoding method serving as a predetermined encoding method; second encoding means configured to encode said audio data using a second encoding method, which is a variable-length encoding method, and also differs from said first encoding method, arranged to add a timing value representing timing employed for a case of being decoded to each predetermined audio data unit; PES packetizing means configured to packetize said audio data encoded by said first encoding means, and said audio data encoded by said second encoding means to PES packets, and also add point-in-time information employed for a case of being decoded to a plurality of said packetized PES packets; TS packetizing means configured to packetize said PES packets PES-packetized by said PES packetizing means to TS packets, and also add the same ID to a plurality of said packetized TS packets including a TS packet comprising audio data encoded by said first encoding method and a TS packet comprising audio data encoded by said second encoding method, add identification information for identifying audio data encoded according to the first encoding method to TS packets comprising audio data encoded by said first encoding method, and add identification information for identifying audio data encoded according to the second encoding method to TS packets comprising audio data encoded by said second encoding method; determining means configured to determine TS packets to be multiplexed from a plurality of said TS packets packetized by said TS packetizing means; and multiplexing means configured to multiplex said TS packets determined by said determining means; wherein said PES packetizing means is configured to packetize said audio data encoded by said first encoding means, and said audio data encoded by said second encoding means to PES packets such that said audio data unit satisfying a predetermined cycle appears at the head of a PES payload; and wherein said determining means is configured to assume a first virtual decoder configured to decode said audio data encoded by said first encoding means, and a second virtual decoder configured to decode said audio data encoded by said second encoding means based on said timing value added to said audio data encoded by said second encoding means, and also to determine TS packets to be multiplexed based on multiplexing constraints arranged to randomly access said multiplexed TS packets.