Patent ID: 7577570

Claim:
Apparatus for spectral envelope adjustment of a signal, comprising: means for providing a plurality of subband signals, a subband signal having associated therewith a channel number k indicating a frequency range covered by the subband signal, the subband signal originating from a channel filter having the channel number k in an analysis filterbank having a plurality of channel filters, wherein the channel filter having the channel number k has a channel response which is overlapped with a channel response of an adjacent channel filter having a channel number k−1 in an overlapping range; means for examining the subband signal having associated therewith the channel number k and for examining an adjacent subband signal having associated therewith the channel number k−1 to determine, whether the subband signal and the adjacent subband signal have aliasing generating signal components in the overlapping range, wherein the means for examining is operative to calculate signs of subband signals based on coefficients of prediction polynomials for the subband signal and the adjacent subband signal, and to indicate a positive result, the positive result being that the subband signal and the adjacent subband signal have aliasing generating signal components in the overlapping range, when the signs have a predetermined relationship to each other, wherein the means for examining is operative to calculate the sign for a subband signal based on the following equation: sign ⁡ ( k ) = { ( - 1 ) k if ⁢ ⁢ α 1 < 0 ( - 1 ) k + 1 if ⁢ ⁢ α 1 ≥ 0 , 0 < k < M , wherein k is the channel number, and α 1 is the first-order coefficient of a prediction polynomial; means for calculating a first gain adjustment value and a second gain adjustment value for the subband signal and the adjacent subband signal in response to the positive result of the means for examining, wherein the means for calculating is operative to determine the first gain adjustment value and the second gain adjustment value dependent on each other; and means for gain adjusting the subband signal and the adjacent subband signal using the first and the second gain adjusting values or for outputting the first and the second gain adjustment values for transmission or storing.