APPARATUS AND METHOD FOR ENCODING/DECODING AN AUDIO SIGNAL USING AN ALIASING SWITCH SCHEME

摘要

AN APPARATUS FOR ENCODING AN AUDIO SIGNAL COMPRISES THE WINDOWER (11) FOR WINDOWING A FIRST BLOCK OF THE AUDIO SIGNAL USING AN ANALYSIS WINDOW HAVING AN ALIASING PORTION AND A FURTHER PORTION. THE APPARATUS FURTHERMORE COMPRISES A PROCESSOR (12) FOR PROCESSING THE FIRST SUB-BLOCK OF THE AUDIO SIGNAL ASSOCIATED WITH THE ALIASING PORTION BY TRANSFORMING THE SUB-BLOCK FROM A DOMAIN INTO A DIFFERENT DOMAIN SUBSEQUENT TO WINDOWING THE FIRST SUB-BLOCK TO OBTAIN THE PROCESSED FIRST SUB-BLOCK, AND FOR PROCESSING A SECOND SUB-BLOCK OF THE AUDIO SIGNAL ASSOCIATED WITH THE FURTHER PORTION BY TRANSFORMING THE SECOND SUB-BLOCK FROM THE DOMAIN INTO THE DIFFERENT DOMAIN BEFORE WINDOWING THE SECOND SUB-BLOCK TO OBTAIN A PROCESSED SECOND SUB-BLOCK. THE APPARATUS FURTHERMORE COMPRISES A TRANSFORMER (13) FOR CONVERTING THE PROCESSED FIRST SUB-BLOCK AND THE PROCESSED SECOND SUB-BLOCK FROM THE DIFFERENT DOMAIN INTO A FURTHER DIFFERENT DOMAIN USING THE SAME BLOCK TRANSFORM RULE TO OBTAIN A CONVERTED FIRST BLOCK WHICH MAY THEN BE COMPRESSED USING ANY OF THE WELL-KNOWN DATA COMPRESSION ALGORITHMS. THUS, A CRITICALLY SAMPLED SWITCH BETWEEN TWO CODING MODES CAN BE OBTAINED, SINCE ALIASING PORTIONS OCCURRING IN TWO DIFFERENT DOMAINS ARE MATCHED TO EACH OTHER.