Patent ID: 6675144
Filing Date: 2004-01-06
Classification: G10L

Abstract:
An audio coding system for encoding and decoding an audio signal, said system including an encoder and a decoder, said encoder comprising:means for decomposing said audio signal into an upper and a lower sub-band signal; lower sub-band coding means for encoding said lower sub-band signal; upper sub-band coding means for encoding at least the non-periodic component of said upper sub-band signal according to a source-filter model; said decoder means comprising means for decoding said encoded lower sub-band signal and said encoded upper sub-band signal, and for reconstructing therefrom an audio output signal, wherein said decoding means comprises filter means and excitation means for generating an excitation signal for being passed by said filter means to produce a synthesised audio signal, said excitation means being operable to generate an excitation signal which includes a substantial component of synthesised noise in an upper frequency band corresponding to the upper sub-band of said audio signal.