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

Patent metadata

Field	Value
Publication number	US-11289104-B2
Application number	US-201916286263-A
Country	US
Kind code	B2
Filing date	Feb 26, 2019
Priority date	Jul 22, 2013
Publication date	Mar 29, 2022
Grant date	Mar 29, 2022

Abstract

An apparatus for decoding an encoded audio signal, includes a spectral domain audio decoder for generating a first decoded representation of a first set of first spectral portions, the decoded representation having a first spectral resolution; a parametric decoder for generating a second decoded representation of a second set of second spectral portions having a second spectral resolution being lower than the first spectral resolution; a frequency regenerator for regenerating every constructed second spectral portion having the first spectral resolution using a first spectral portion and spectral envelope information for the second spectral portion; and a spectrum time converter for converting the first decoded representation and the reconstructed second spectral portion into a time representation.

First claim

The invention claimed is:

1. An apparatus for decoding an encoded audio signal, comprising:
a spectral domain audio decoder for generating a first decoded representation of a first set of first spectral portions, the first decoded representation comprising a first spectral resolution;
a parametric decoder for generating a second decoded representation of a second set of second spectral portions, the second decoded representation comprising spectral envelope information comprising a second spectral resolution being lower than the first spectral resolution;
a frequency regenerator for regenerating a reconstructed second spectral portion comprising the first spectral resolution using a first spectral portion of the first set of first spectral portions and spectral envelope information for a second spectral portion of the second set of second spectral portions; and
a spectrum time converter for converting the first decoded representation and the reconstructed second spectral portion into a time representation,
wherein the apparatus for decoding is configured to generate the first decoded representation so that the first spectral portion of the first set of first spectral portions is placed, with respect to frequency, between two second spectral portions of the second set of second spectral portions.

2. The apparatus according to claim 1 , wherein the parametric decoder is configured for generating the second decoded representation comprising matching information on the first spectral portion matching with the second spectral portion, and
wherein the frequency regenerator is configured for regenerating the reconstructed second spectral portion using the first spectral portion identified by the matching information.

3. The apparatus according to claim 1 , wherein the spectral domain audio decoder is configured to output a sequence of decoded frames of spectral values, a decoded frame of the sequence of decoded frames being the first decoded representation, wherein the frame comprises spectral values for the first set of first spectral portions and zero indications for the second set of second spectral portions,
wherein the apparatus for decoding further comprises a combiner configured for combining spectral values generated by the frequency regenerator for the second set of second spectral portions and spectral values of the first set of first spectral portions in a reconstruction band to acquire a reconstructed spectral frame comprising spectral values for the first set of the first spectral portions and the second set of second spectral portion, and
wherein the spectrum-time converter is configured to convert the reconstructed spectral frame into the time representation.

4. The apparatus according to claim 1 , wherein the spectrum-time converter is configured to perform an inverse modified discrete cosine transform, and further comprises an overlap-add stage configured for overlapping and adding subsequent time domain frames, each subsequent time domain frame originating from a spectrum representation comprising the first decoded representation and the reconstructed second spectral portion.

5. The apparatus according to claim 1 ,
wherein the spectral domain audio decoder is configured to generate the first decoded representation so that the first decoded representation has a Nyquist frequency defining a sampling rate being equal to a sampling rate of the time representation generated by the spectrum-time converter.

6. The apparatus according to claim 1 , wherein a maximum frequency represented by a spectral value for the maximum frequency in the first decoded representation is equal to a maximum frequency comprised by the time representation generated by the spectrum-time converter, wherein the spectral value for the maximum frequency in the first representation is zero or different from zero.

7. The apparatus according to claim 1 ,
wherein the encoded audio signal comprises a first encoded representation being a frequency domain encoded version of the first set of first spectral portions and a second encoded representation of the second set of second spectral portions,
wherein the apparatus further comprises a data stream parser configured for extracting the first encoded representation and configured for forwarding the first encoded representation to the spectral domain audio decoder and configured for extracting the second encoded representation and configured for forwarding the second encoded representation to the parametric decoder.

8. The apparatus according to claim 1 , wherein the encoded audio signal further comprises an encoded representation of a third set of third spectral portions to be reconstructed by noise filling, further comprising:
a noise filler configured for extracting noise filling information from the encoded representation of the third set of third spectral portions and configured for applying a noise filling operation in the third set of third spectral portions without using the first spectral portion of the first set of first spectral portions in a different frequency range to generate a reconstructed third spectral portion,
wherein the spectrum-time converter is configured for additionally converting the third set of third spectral portion into the time representation.

9. The apparatus according to claim 1 ,
wherein the spectral domain audio decoder is configured to generate the first decoded representation comprising the first spectral portions with frequency values being greater than a frequency being equal to a frequency in a middle of a frequency range covered by the time representation output by the spectrum-time converter.

10. The apparatus according to claim 1 ,
wherein the frequency regenerator is configured to generate a reconstruction band comprising a spectral portion of the first set of first spectral portions at a frequency in the reconstruction band being different from a center frequency of the reconstruction band, wherein the reconstruction band is a scale factor band, for which an energy value indicating a spectral envelope information is comprised by the second set of second spectral portions comprising the second spectral resolution.

11. A method of decoding an encoded audio signal, comprising:
generating a first decoded representation of a first set of first spectral portions, the first decoded representation comprising a first spectral resolution;
generating a second decoded representation of a second set of second spectral portions, the second decoded representation comprising spectral envelope information 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 of the first set of first spectral portions and the spectral envelope information for a second spectral portion of the second set of second spectral portions; and
converting the first decoded representation and the reconstructed second spectral portion into a time representation,
wherein the generating the first decoded representation generates the first decoded representation so that the first spectral portion of the first set of first spectral portions is placed, with respect to frequency, between two second spectral portions of the second set of second spectral portions.

12. A non-transitory digital storage medium having a computer program stored thereon to perform, when the computer program is run by a computer, the method of decoding an encoded audio signal, the method comprising:
generating a first decoded representation of a first set of first spectral portions, the first decoded representation com

Assignees

• Fraunhofer Ges Forschung

Inventors

• Disch Sascha
• Nagel Frederik
• Geiger Ralf
• Thoshkahna Balaji Nagendran
• Schmidt Konstantin
• Bayer Stefan
• Neukam Christian
• Edler Bernd
• Helmrich Christian

Classifications

• G10L19/022

  Blocking, i.e. grouping of samples in time; Choice of analysis windows; Overlap factoring · CPC title

• G10L21/038

  using band spreading techniques · CPC title

• G10L19/008 Primary

  Multichannel audio signal coding or decoding using interchannel correlation to reduce redundancy, e.g. joint-stereo, intensity-coding or matrixing · CPC title

• G10L25/21

  the extracted parameters being power information · CPC title

• G10L25/18

  the extracted parameters being spectral information of each sub-band · CPC title