Method for reduction of aliasing introduced by spectral envelope adjustment in real-valued filterbanks
First Claim
Patent Images
1. Method for reducing or eliminating intermodulation introduced by aliasing in a real-valued filterbank used for spectral envelope adjustment, comprising:
- analysing an input signal to obtain information; and
using the obtained information to restrain envelope adjustment capabilities of the real-valued filterbank by grouping gain-values of adjacent channels of the real-valued filterbank,wherein the real-valued filterbank is configured for generating a plurality of subband signals generated by filtering a signal using an analysis filterbank, the real-valued filterbank having subband filters, adjacent subband filters of the filterbank having transition bands overlapping in an overlapping range, andwherein the analysing comprises examining a subband signal originating from a subband filter and an adjacent subband signal originating from an adjacent subband filter to determine, whether the subband signal and the adjacent subband signal have aliasing generating signal components in the overlapping range to obtain grouped subband signals in response to a specific result of the examination, the specific result of the examination indicating that the subband signal and the adjacent subband signal have aliasing generating signal components in the overlapping range.
0 Assignments
0 Petitions
Accused Products
Abstract
The present invention proposes a new method for improving the performance of a real-valued filterbank based spectral envelope adjuster. By adaptively locking the gain values for adjacent channels dependent on the sign of the channels, as defined in the application, reduced aliasing is achieved. Furthermore, the grouping of the channels during gain-calculation, gives an improved energy estimate of the real valued subband signals in the filterbank.
44 Citations
11 Claims
-
1. Method for reducing or eliminating intermodulation introduced by aliasing in a real-valued filterbank used for spectral envelope adjustment, comprising:
-
analysing an input signal to obtain information; and using the obtained information to restrain envelope adjustment capabilities of the real-valued filterbank by grouping gain-values of adjacent channels of the real-valued filterbank, wherein the real-valued filterbank is configured for generating a plurality of subband signals generated by filtering a signal using an analysis filterbank, the real-valued filterbank having subband filters, adjacent subband filters of the filterbank having transition bands overlapping in an overlapping range, and wherein the analysing comprises examining a subband signal originating from a subband filter and an adjacent subband signal originating from an adjacent subband filter to determine, whether the subband signal and the adjacent subband signal have aliasing generating signal components in the overlapping range to obtain grouped subband signals in response to a specific result of the examination, the specific result of the examination indicating that the subband signal and the adjacent subband signal have aliasing generating signal components in the overlapping range. - View Dependent Claims (2, 3, 4)
-
-
5. Apparatus for reducing or eliminating intermodulation introduced by aliasing in a real-valued filterbank used for spectral envelope adjustment, comprising:
-
an analyser for analysing an input signal to obtain information; and a user configured for using the obtained information to restrain envelope adjustment capabilities of the real-valued filterbank by grouping gain-values of adjacent channels of the real-valued filterbank, wherein the real-valued filterbank is configured for generating a plurality of subband signals generated by filtering a signal using an analysis filterbank, the real-valued filterbank having subband filters, adjacent subband filters of the filterbank having transition bands overlapping in an overlapping range, and wherein the analyser comprises an examiner for examining a subband signal originating from a subband filter and an adjacent subband signal originating from an adjacent subband filter to determine, whether the subband signal and the adjacent subband signal have aliasing generating signal components in the overlapping range to obtain grouped subband signals in response to a specific result of the examination, the specific result of the examination indicating that the subband signal and the adjacent subband signal have aliasing generating signal components in the overlapping range. - View Dependent Claims (6, 7, 8, 9, 10, 11)
-
Specification