OVERSAMPLING IN A COMBINED TRANSPOSER FILTER BANK

摘要

The present invention relates to coding of audio signals, and in particular to high frequency reconstruction methods including a frequency domain harmonic transposer. A system and method for generating a high frequency component of a signal from a low frequency component of the signal is described. The system comprises an analysis filter bank (501) comprising an analysis transformation unit (601) having a frequency resolution of ? ; and an analysis window (611) having a duration of D A ; the analysis filter bank (501) being configured to provide a set of analysis subband signals from the low frequency component of the signal; a nonlinear processing unit (502, 650) configured to determine a set of synthesis subband signals based on a portion of the set of analysis subband signals, wherein the portion of the set of analysis subband signals is phase shifted by a transposition order T; and a synthesis filter bank (504) comprising a synthesis transformation unit (602) having a frequency resolution of Q? ; and a synthesis window (612) having a duration of D s ; the synthesis filter bank (504) being configured to generate the high frequency component of the signal from the set of synthesis subband signals; wherein Q is a frequency resolution factor with Q = 1 and smaller than the transposition order T; and wherein the value of the product of the frequency resolution ? and the duration D A of the analysis filter bank is selected based on the frequency resolution factor Q.