A decoder is provided which includes a demultiplexing unit for separating a multiplexed
stream into plural streams by a demultiplexing process and a decoding unit for
carrying out a decoding process for one of the plural separated streams, wherein
the decoder selects one of the plural separated streams to output the same to the
decoding unit such that a decoding process for one stream in the decoding unit
is switched to a decoding process for another stream. The decoder is thus able
to decode plural streams composing a multiplexed stream with one decoding unit.
