Apparatus and method for encoding or decoding an audio signal with intelligent gap filling in the spectral domain

An apparatus for encoding an audio signal, comprising:

• a time-spectrum converter for converting an audio signal comprising a sampling rate into a spectral representation;
• a spectral analyzer for analyzing the spectral representation for determining a first set of first spectral portions to be encoded with a first spectral resolution and a different second set of second spectral portions to be encoded with a second spectral resolution, the second spectral resolution being smaller than the first spectral resolution, wherein a first spectral portion is placed, with respect to frequency, between two second spectral portions;
• a spectral domain audio encoder for generating a first encoded representation of the first set of spectral portions comprising the first spectral resolution;
• and
• a parametric coder for calculating spectral envelope information for the second set of second spectral portions comprising the second spectral resolution.

A method of decoding an encoded audio signal, comprising:

• generating a first decoded representation of a first set of first spectral portions, the decoded representation comprising a first spectral resolution;
• generating a second decoded representation of a second set of second spectral portions comprising a second spectral resolution being lower than the first spectral resolution;
• regenerating a reconstructed second spectral portion comprising the first spectral resolution using a first spectral portion and spectral envelope information for the second spectral portion;
• and
• converting the first decoded representation and the reconstructed second spectral portion into a time representation.

A method for encoding an audio signal, comprising:

• converting an audio signal comprising a sampling rate into a spectral representation;
• analyzing the spectral representation for determining a first set of first spectral portions to be encoded with a first spectral resolution and a different second set of second spectral portions to be encoded with a second spectral resolution, the second spectral resolution being smaller than the first spectral resolution, wherein a first spectral portion is placed, with respect to frequency, between two second spectral portions;
• for generating a first encoded representation of the first set of spectral portions comprising the first spectral resolution;
• and
• calculating spectral envelope information for the second set of second spectral portions comprising the second spectral resolution.

A non-transitory digital storage medium having a computer program stored thereon to perform the method of decoding an encoded audio signal, comprising:

• generating a first decoded representation of a first set of first spectral portions, the decoded representation comprising a first spectral resolution;
• generating a second decoded representation of a second set of second spectral portions comprising a second spectral resolution being lower than the first spectral resolution;
• regenerating a reconstructed second spectral portion comprising the first spectral resolution using a first spectral portion and spectral envelope information for the second spectral portion;
• and
• converting the first decoded representation and the reconstructed second spectral portion into a time representation,
• when said computer program is run by a computer.

A non-transitory digital storage medium having a computer program stored thereon to perform the method for encoding an audio signal, comprising:

• converting an audio signal comprising a sampling rate into a spectral representation;
• analyzing the spectral representation for determining a first set of first spectral portions to be encoded with a first spectral resolution and a different second set of second spectral portions to be encoded with a second spectral resolution, the second spectral resolution being smaller than the first spectral resolution, wherein a first spectral portion is placed, with respect to frequency, between two second spectral portions;
• for generating a first encoded representation of the first set of spectral portions comprising the first spectral resolution;
• and
• calculating spectral envelope information for the second set of second spectral portions comprising the second spectral resolution,
• when said computer program is run by a computer.