Efficient combined harmonic transposition

摘要

The present document relates to audio coding systems which make use of a harmonic transposition method for high frequency reconstruction (HFR), and to digital effect processors, e.g. so-called exciters, where generation of harmonic distortion adds brightness to the processed signal. In particular; a system configured to generate a high frequency component of a signal from a low frequency component of the signal is described, The system may comprise an analysis filter bank (501) configured to provide a set of analysis subband signals from the low frequency component of the signal; wherein the set of analysis subband signals comprises at least two analysis subband signals; wherein the analysis filter bank (501) has a frequency resolution of Δf, The system further comprises a nonlinear processing unit (502) configured to determine a set of synthesis subband signals from the set of analysis subband signals using a transposition order P; wherein the set of synthesis subband signals comprises a portion of the set of analysis subband signals phase shifted by an amount derived from the transposition order P; and a synthesis filter bank (504) configured to generate the high frequency component of the signal from the set of synthesis subband signals; wherein the synthesis filter bank (504) has a frequency resolution of FΔf; with F being a resolution factor, with F≧1; wherein the transposition order P is different from the resolution factor F.

主权项

1. A system configured to generate a high frequency component of an audio signal from a low frequency component of the audio signal, the system comprising:
an analysis filter bank configured to provide a set of analysis subband signals from the low frequency component of the signal; wherein the set of analysis subband signals comprises at least two analysis subband signals; wherein the analysis filter bank has a frequency resolution of Δf ; wherein the analysis filter bank has a number LA of analysis subbands, with LA>1, where k is an analysis subband index with k=0, . . . , LA−1; a nonlinear processing unit configured to determine a set of synthesis subband signals from the set of analysis subband signals using a transposition order P; wherein the set of synthesis subband signals is determined based on a portion of the set of analysis subband signals phase shifted by an amount derived from the transposition order P; and a synthesis filter bank configured to generate the high frequency component of the signal from the set of synthesis subband signals; wherein the synthesis filter bank has a frequency resolution of FΔf ; with F being a resolution factor, with F≧1; wherein the transposition order P is different from the resolution factor F ; wherein the synthesis filter bank has a number LS of synthesis subbands, with LS>0, where n is a synthesis subband index with n=0, . . . , LS−1; wherein the nonlinear processing unit is configured to determine an nth synthesis subband signal of the set of synthesis subband signals from a kth analysis subband signal and a (k+1)th analysis subband signal of the set of analysis subband signals.