Apparatus and method for encoding and decoding an encoded audio signal using temporal noise/patch shaping

Patent metadata

Field	Value
Publication number	US-11049506-B2
Application number	US-201916417471-A
Country	US
Kind code	B2
Filing date	May 20, 2019
Priority date	Jul 22, 2013
Publication date	Jun 29, 2021
Grant date	Jun 29, 2021

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 being spectral prediction residual values; a frequency regenerator for generating a reconstructed second spectral portion using a first spectral portion of the first set of first spectral portions, wherein the reconstructed second spectral portion additionally includes spectral prediction residual values; and an inverse prediction filter for performing an inverse prediction over frequency using the spectral residual values for the first set of first spectral portions and the reconstructed second spectral portion using prediction filter information included in the encoded audio signal.

First claim

The invention claimed is:

1. Apparatus for decoding an encoded audio signal, comprising:
a spectral domain audio decoder configured for generating a decoded representation of a first set of first spectral portions, the decoded representation of the first set of first spectral portions comprising first set spectral prediction residual values;
a frequency regenerator configured for generating reconstructed spectral prediction residual values of a reconstructed second spectral portion using the first set spectral prediction residual values of a first spectral portion of the first set of first spectral portions, wherein the reconstructed second spectral portion is different, with respect to frequency, from the first spectral portion of the first set of first spectral portions; and
an inverse prediction filter configured for performing an inverse prediction over frequency using, as a filter input, the first set spectral prediction residual values for the first set of first spectral portions and the reconstructed spectral prediction residual values for the reconstructed second spectral portion using prediction filter information comprised in the encoded audio signal.

2. Apparatus for decoding of claim 1 ,
further comprising a spectral envelope shaper configured for shaping a spectral envelope of the first set spectral prediction residual values for the first set of first spectral portions and the reconstructed spectral prediction residual values for the reconstructed second spectral portion, as an input signal of the inverse prediction filter, or for shaping a spectral envelope of an output signal of the inverse prediction filter.

3. Apparatus for decoding of claim 2 ,
wherein the encoded audio signal comprises spectral envelope information for the second spectral portion, the spectral envelope information comprising a second spectral resolution, the second spectral resolution being lower than a first spectral resolution associated with the first set spectral prediction residual values of the decoded representation,
wherein the spectral envelope shaper is configured to apply a spectral envelope shaping operation on the output of the inverse prediction filter, wherein the filter information has been determined by using an audio signal before prediction filtering, or
wherein the spectral envelope shaper is configured to apply a spectral envelope shaping operation on the input of the inverse prediction filter, when the prediction filter information has been determined by using an audio signal subsequent to a prediction filtering in an encoder.

4. Apparatus for decoding of claim 1 ,
further comprising a frequency time-converter configured for converting an output of the inverse prediction filter or an envelope shaped output of the inverse prediction filter into a time representation.

5. Apparatus for decoding of claim 1 ,
wherein the inverse prediction filter is a complex filter defined by the prediction filter information.

6. Apparatus for decoding of claim 1 ,
wherein the spectral domain audio decoder is configured to generate the first set spectral prediction residual values of the decoded representation so that the first set spectral prediction residual values of the decoded representation comprise a Nyquist frequency equal to a sampling rate of a time domain signal generated by a frequency-time conversion of an output of the inverse prediction filter.

7. Apparatus for decoding of claim 1 ,
wherein the spectral domain audio decoder is configured so that a maximum frequency represented by a first set spectral prediction residual value for the maximum frequency of the decoded representation is equal to a maximum frequency comprised in a time representation generated by frequency-time converting an output of the inverse prediction filter, wherein the first set spectral prediction residual value for the maximum frequency in the first representation is zero or different from zero.

8. Apparatus for decoding of claim 1 ,
wherein the first set spectral prediction residual values of the decoded representation of the first set of first spectral portions comprises real-valued spectral prediction residual values,
wherein the apparatus further comprises an estimator configured for estimating imaginary spectral prediction residual values for the first set spectral prediction residual values of the first set of first spectral portions from the real-valued spectral prediction residual portions values, wherein the inverse prediction filter is a complex inverse prediction filter defined by complex-valued prediction filter information and wherein the complex inverse prediction filter is configured to perform the inverse prediction over frequency using the real-valued spectral prediction residual values and the imaginary spectral prediction residual values, and wherein the apparatus further comprises a frequency-time converter configured for performing a conversion of a complex-valued spectrum output by the complex inverse prediction filter into a time domain audio signal.

9. Apparatus for decoding of claim 1 ,
wherein the inverse prediction filter is configured to apply a plurality of subfilters to the first set spectral prediction residual values for the first set of first spectral portions and to the reconstructed spectral prediction residual values for the reconstructed second spectral portion, wherein a frequency border of each subfilter coincides with a frequency border of a reconstruction band comprising a reconstructed second spectral portion coinciding with a frequency tile.

10. Apparatus for encoding an audio signal, comprising:
a time frequency converter configured for converting the audio signal into a spectral representation comprising spectral values;
a prediction filter configured for performing a prediction over frequency on the spectral values of the spectral representation, as a filter input, to generate first set spectral prediction residual values for a first set of first spectral portions and to generate second set spectral prediction residual values for a second set of second spectral portions, the prediction filter being defined by filter information derived from the audio signal;
an audio coder configured for encoding the first set spectral prediction residual values of the first set of first spectral portions to acquire encoded first set spectral prediction residual values of the first set of first spectral portions comprising a first spectral resolution;
a parametric coder configured for parametrically coding the second set spectral prediction residual values for the second set of second spectral portions or for parametrically coding the spectral values of the spectral representation with a second spectral resolution being lower than the first spectral resolution to obtain a parametrically encoded second set of second spectral portions, wherein the second spectral portions of the second set of second spectral portions are different, with respect to frequency, from the first spectral portions of the first set of first spectral portions; and
an output interface configured for outputting an encoded signal, the encoded signal comprising the parametrically encoded second set of first spectral portions, the encoded first set spectral prediction residual values of the first set and the filter information.

11. Apparatus for encoding of claim 10 ,
wherein the time frequency converter is configured for performing a modified discrete cosine transform, and wherein the first set spectral prediction residual values are first set modified discrete cosine transform spectral prediction residual values and the second set spectral prediction residual values are second set modified discrete cosine tra

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