Efficient combined harmonic transposition

Patent metadata

Field	Value
Publication number	US-11200874-B2
Application number	US-202016876793-A
Country	US
Kind code	B2
Filing date	May 18, 2020
Priority date	May 27, 2009
Publication date	Dec 14, 2021
Grant date	Dec 14, 2021

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.

First claim

The invention claimed is:

1. An audio signal processing device comprising one or more processors configured to generate a high frequency component of a signal from a low frequency component of the signal, wherein the one or more processors:
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;
determine a set of synthesis subband signals from the set of analysis subband signals; wherein the nonlinear processing unit is configured to determine an n th synthesis subband signal of the set of synthesis subband signals from a k th analysis subband signal and a (k+1) th analysis subband signal of the set of analysis subband signals; wherein a magnitude of the n th synthesis subband signal is determined from a product of an exponentiated magnitude of the k th analysis subband signal and an exponentiated magnitude of the (k+1) th analysis subband signal; and
generate the high frequency component of the signal based on the set of synthesis subband signals.

2. The audio signal processing device of claim 1 , wherein the one or more processors:
convert an encoded bit stream into the low frequency component of the signal;
convert the high frequency component into a plurality of QMF subband signals;
modify the QMF subband signals; and
generate a modified high frequency component from the modified QMF subband signals.

3. A method for generating a high frequency component of a signal from a low frequency component of the signal, the method comprising:
providing 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;
determining a set of synthesis subband signals from the set of analysis subband signals, such that an n th synthesis subband signal of the set of synthesis subband signals is determined from a k th analysis subband signal and a (k+1) th analysis subband signal of the set of analysis subband signals; wherein a magnitude of the n th synthesis subband signal is determined from a product of an exponentiated magnitude of the k th analysis subband signal and an exponentiated magnitude of the (k+1) th analysis subband signal; and
generating the high frequency component of the signal based on the set of synthesis subband signals.

4. The method of claim 3 , wherein
the set of analysis subband signals is generated from the low frequency component using an analysis filter bank; and
the high frequency component is generated from the set of synthesis subband signals using a synthesis filter bank.

5. A non-transitory computer readable storage medium comprising a sequence of instructions, wherein, when executed by an audio signal processing device, the sequence of instructions causes the device to perform a method for generating a high frequency component of a signal from a low frequency component of the signal, the method comprising:
providing 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; determining a set of synthesis subband signals from the set of analysis subband signals, such that an n th synthesis subband signal of the set of synthesis subband signals is determined from a k th analysis subband signal and a (k+1) th analysis subband signal of the set of analysis subband signals; wherein a magnitude of the n th synthesis subband signal is determined from a product of an exponentiated magnitude of the k th analysis subband signal and an exponentiated magnitude of the (k+1) th analysis subband signal; and
generating the high frequency component of the signal based on the set of synthesis subband signals.

Assignees

• Dolby Int Ab

Inventors

• Ekstrand Per
• Villemoes Lars
• Hedelin Per

Classifications

• G10L21/0388

  Details of processing therefor · CPC title

• G10L21/038 Primary

  using band spreading techniques · CPC title

• G10L19/265

  Pre-filtering, e.g. high frequency emphasis prior to encoding · CPC title

• H03M7/30

  Compression (speech analysis-synthesis for redundancy reduction G10L19/00; for image communication H04N); Expansion; Suppression of unnecessary data, e.g. redundancy reduction · CPC title

• G10L19/00

  Speech or audio signals analysis-synthesis techniques for redundancy reduction, e.g. in vocoders; Coding or decoding of speech or audio signals, using source filter models or psychoacoustic analysis (in musical instruments G10H) · CPC title