Efficient combined harmonic transposition
First Claim
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 set of analysis subband signals comprises at least two analysis subband signals;
wherein the analysis filter bank has a frequency resolution of Δ
f;
a nonlinear processing unit configured to determine a set of synthesis subband signals from the set of analysis subband signals;
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; and
a synthesis filter bank configured to generate the high frequency component of the signal based on the set of synthesis subband signals;
wherein the synthesis filter bank has a frequency resolution of FΔ
f;
with F being a resolution factor, with F≧
1;
wherein the analysis filter bank and the synthesis filter bank are evenly stacked such that a center frequency of an analysis subband is given by kΔ
f and a center frequency of a synthesis subband is given by nFΔ
f;
wherein the analysis filter bank, the nonlinear processing unit, or the synthesis filter bank are implemented at least in part in hardware;
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; and
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.
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Accused Products
Abstract
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.
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Citations
15 Claims
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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 set of analysis subband signals comprises at least two analysis subband signals;
wherein the analysis filter bank has a frequency resolution of Δ
f;a nonlinear processing unit configured to determine a set of synthesis subband signals from the set of analysis subband signals;
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; anda synthesis filter bank configured to generate the high frequency component of the signal based on the set of synthesis subband signals;
wherein the synthesis filter bank has a frequency resolution of FΔ
f;
with F being a resolution factor, with F≧
1;
wherein the analysis filter bank and the synthesis filter bank are evenly stacked such that a center frequency of an analysis subband is given by kΔ
f and a center frequency of a synthesis subband is given by nFΔ
f;wherein the analysis filter bank, the nonlinear processing unit, or the synthesis filter bank are implemented at least in part in hardware;
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; and
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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method for generating a high frequency component of a signal from a low frequency component of the signal, the method comprising:
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providing a set of analysis subband signals from the low frequency component of the signal using an analysis filter bank;
wherein the set of analysis subband signals comprises at least two analysis subband signals;
wherein the analysis filter bank has a frequency resolution of Δ
f;determining a set of synthesis subband signals from the set of analysis subband signals, such that an nth synthesis subband signal of the set of synthesis subband signals is determined from a kth analysis subband signal and a (k+1)th analysis subband signal of the set of analysis subband signals; and generating the high frequency component of the signal based on the set of synthesis subband signals using a synthesis filter bank;
wherein the synthesis filter bank has a frequency resolution of FΔ
f;
with F being a resolution factor, with F>
1;
wherein the analysis filter bank and the synthesis filter bank are evenly stacked such that a center frequency of an analysis subband is given by kΔ
f and a center frequency of a synthesis subband is given by nFΔ
f;
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; and
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.
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Specification