Patent ID: 7003451

Claim:
An apparatus for estimating a level of spectral whitening to be applied to a signal prior to a high-frequency regeneration step or after the high-frequency regeneration step to be performed when generating a high-frequency regenerated signal having a highband which is based on a lowband signal, wherein the spectral whitening is obtained by filtering using a spectral whitening filter, the spectral whitening filter being an adaptive filter being adaptable by means of a filter parameter, the apparatus comprising: an estimator for estimating a tonal character of an original signal to be encoded, at a given time, wherein the original audio signal is to be encoded by an audio coder to obtain an encoded audio signal representing only a lowband of the original audio signal, the estimated tonal character including an estimated tonal character of a highband of the original audio signal, which is not included in the encoded audio signal; a determinator for determining a varying filter parameter of the spectral whitening filter based on the estimated tonal character; and an associator for associating the varying filter parameter to the encoded audio signal to obtain a bit stream having the encoded audio signal having the varying filter parameter, the varying filter parameter being dependent on the encoded audio signal.