Low bit-rate high-resolution spectral envelope coding for audio encoder and decoder

A decoder of an encoded signal generated by an encoder comprising an analysis filter bank, said decoder comprising

• deformatting means for extracting from said encoded signal one or more scaled values and differential coded representations of one or more scale factors,
• integrating means for generating scaled representations in response to said one or more scaled values and said differential coded representations, each scaled representation comprising a scaling factor associated with one or more scaled values, wherein each differential coded representation represents a difference between a respective scaling factor and a base value or another scaling factor and said integrating means is limited to integrating differences restricted in accordance with spectral selectivity of said analysis filter bank,
• inverse scaling means for generating a subband signal block comprising a plurality of subband signals, wherein one or more of said subband signals is generated in response to a respective one of said scaled representations, and
• inverse splitband means for generating one or more channels of output signals by applying to said subband signal block a signal synthesis filter bank inverse to said signal analysis filter bank.

An encoding method of one or more channels of input signals comprising signal samples, said encoding method comprising

• generating a subband signal block comprising a plurality of subband signals by applying a filter bank to said channels of input signals, each subband signal representing a respective frequency subband of said channels of input signals,
• generating scaled representations of two or more subband signals, each of said scaled representations comprising a scaling factor associated with one or more scaled values, wherein said generating scaled representations comprises adjusting the value of said scaling factor and said scaled values in a respective one of said scaled representations to restrict the magnitude of a difference between said scaling factor and a scaling factor in another of said scaled representations in accordance with frequency selectivity characteristics of said filter bank such that information requirements of an encoded signal are reduced,
• generating differential coded representations of one or more of said scaling factors, and
• generating an encoded signal comprising said scaled values and said differential coded representations.

A decoding method for decoding an encoded signal generated by an encoder comprising an analysis filter bank, said decoding method comprising

• extracting from said encoded signal one or more scaled values and differential coded representations of one or more scale factors, wherein said extracting is limited to extracting differential coded representations in which magnitudes of differentials are restricted in accordance with spectral selectivity of said analysis filter bank,
• generating scaled representations in response to said one or more scaled values and said differential coded representations, each scaled representation comprising a scaling factor associated with one or more scaled values, wherein each differential coded representation represents a difference between a respective scaling factor and a base value or another scaling factor,
• generating a subband signal block comprising a plurality of subband signals, wherein one or more of said subband signals is generated in response to a respective one of said scaled representations, and
• generating one or more channels of output signals by applying to said subband signal block a signal synthesis filter band inverse to said signal analysis filter bank.