1. A decoder, comprising: a pre-unit, for providing a packet information of a data stream; a database, for recording a plurality of setting parameter sets; at least one data filter, for comparing the data stream with a operation parameter set saved therein, and outputting a comparing result; and a scheduler, coupled to the pre-unit, the database, and the data filter, for fetching corresponding at least one setting parameter set from the database according to the packet information provided by the pre-unit and saving the setting parameter set fetched from the database into the data filter as the operation parameter set.