Format conversion apparatus, the format conversion method and a moving picture decoding system

A format converter for converting the format of input contents data from a first format standard to a second format standard includes an extraction section ( 30 ), a judgment section ( 40 ), a determination section ( 60 ) and a conversion section ( 70 ). The extraction section ( 30 ) extracts information related to encoding of the input contents data. The judgment section ( 40 ) judges whether or not the contents data satisfies a constraint placed by the second format standard based on the extracted information. The determination section ( 60 ) determines whether or not decoding of the contents data is necessary for the format conversion based on the judgment result. The conversion section ( 70 ) performs the format conversion by converting data structure when it is determined that the decoding is unnecessary.