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 a signal from a low frequency component of the 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 analysis filter bank has a frequency resolution of Δf; a first nonlinear processing unit configured to determine a first set of synthesis subband signals from the set of analysis subband signals using a first transposition order P1; a second nonlinear processing unit configured to determine a second set of synthesis subband signals from the set of analysis subband signals using a second transposition order P2; wherein the second nonlinear processing unit is configured to determine a set of intermediate synthesis subband signals having a frequency resolution of P2Δf; and interpolate one or more intermediate synthesis subband signals to determine the synthesis subband signal of the second set of synthesis subband signals having the frequency resolution of FΔf, with F being a resolution factor, with F≧1; a combining unit configured to combine the first and the second set of synthesis subband signals; thereby yielding a combined set of synthesis subband signals; and a synthesis filter bank configured to generate the high frequency component of the signal from the combined set of synthesis subband signals; wherein the synthesis filter bank has a frequency resolution of FΔf.