FILTERING PROCESSING METHOD AND FILTERING PROCESSOR

摘要

PROBLEM TO BE SOLVED: To reduce the number of operation times on a filtering processing in the decoding of a digital signal and to reduce cost required for decoding. SOLUTION: A filtering processing method is performed when the digital signal is decoded in a time area from a frequency area. The method includes a first step for obtaining an output data string constituted of a plurality of data blocks by multiplying a conversion matrix smaller than an inverse MDCT conversion matrix obtained by resolving a conversion matrix for inversely MDCT-converting an input data string constituted of a plurality of data blocks into super matrixes by the input data string, a second step for storing prescribed data included in the respective data blocks of the output data string and a third step for generating the digital signal of the time area based on the respective data blocks obtained in the first step and on prescribed data stored in the second step of the processing of the data block in a preceding stage.