Patent ID: 8812327

Claim:
A method for hierarchically coding a digital audio frequency input signal as several frequency sub-bands comprising: a core coding of the input signal in a low frequency band according to a first bit rate, the core coding using a first binary allocation according to an energy criterion; and at least one improvement coding of a higher bit rate of a residual signal in a high frequency band, wherein the improvement coding comprises: calculation of a frequency masking threshold for at least part of the frequency bands processed by the improvement coding, the masking threshold being normalized by the value of the masking threshold at a last sub-band of the low frequency band and/or a first sub-band of the high frequency band; determination of a perceptual importance per frequency sub-band of the high frequency band as a function of the masking threshold calculated and as a function of the number of bits allocated for the core coding; second binary allocation of bits in the frequency sub-bands of the high frequency band processed by the improvement coding, as a function of the perceptual importance determined; and coding of the residual signal according to the second binary allocation of bits.