Audio encoder, audio decoder and related methods using two-channel processing within an intelligent gap filling framework

Patent metadata

Field	Value
Publication number	US-11735192-B2
Application number	US-202217576780-A
Country	US
Kind code	B2
Filing date	Jan 14, 2022
Priority date	Jul 22, 2013
Publication date	Aug 22, 2023
Grant date	Aug 22, 2023

Abstract

An apparatus for generating a decoded two-channel signal, comprising: a parametric decoder for providing parametric data for a second set of second spectral portions and a two-channel identification identifying for a second spectral portion of the second set of second spectral portions either a first two-channel representation for the second spectral portion of the second set of second spectral portions or a second two-channel representation for the second spectral portion of the second set of second spectral portions, the second two-channel representation being different from the first two-channel representation; and a frequency regenerator for regenerating the second spectral portion of the second set of second spectral portions depending on a first spectral portion of a first set of first spectral portions, the parametric data for the second spectral portion of the second set of second spectral portions and the two-channel identification for the second spectral portion of the second set of second spectral portions to acquire a regenerated second spectral portion of the second set of second spectral portions.

First claim

The invention claimed is:

1. Apparatus for generating a decoded two-channel signal, comprising:
a parametric decoder for providing parametric data for a second set of second spectral portions and a two-channel identification identifying for a second spectral portion of the second set of second spectral portions either a first two-channel representation for the second spectral portion of the second set of second spectral portions or a second two-channel representation for the second spectral portion of the second set of second spectral portions, the second two-channel representation being different from the first two-channel representation; and
a frequency regenerator for regenerating the second spectral portion of the second set of second spectral portions depending on a first spectral portion of a first set of first spectral portions, the parametric data for the second spectral portion of the second set of second spectral portions and the two-channel identification for the second spectral portion of the second set of second spectral portions to acquire a regenerated second spectral portion of the second set of second spectral portions.

2. Apparatus of claim 1 , wherein the first two-channel identification identifies a separate processing of two channels of the encoded two-channel signal and wherein the second two-channel identification identifies a joint processing of the two channels of the encoded two-channel signal, and
wherein the frequency regenerator is configured for regenerating the second spectral portion for a first channel of the two channels and the second spectral portion for a second channel of the two channels using the first spectral portion of the first channel and the first spectral portion of the second channel, wherein the first spectral portion of the first channel and the first spectral portion of the second channel are in the first two-channel representation or in the second two-channel representation as identified by the two-channel identification for the second spectral portion.

3. Apparatus of claim 1 ,
wherein the first two-channel identification identifies a separate processing of two channels of the encoded two-channel signal, and wherein the second two-channel identification identifies a joint processing of the two channels of the encoded two-channel signal, and
wherein the frequency regenerator is configured for regenerating a joint representation of the two channels in the second spectral portion as identified by the two-channel identification, and
wherein the frequency regenerator further comprises a representation transformer for transforming the joint representation of the second spectral portion into a separate representation for the second spectral portion.

4. Apparatus of claim 3 , wherein the representation transformer uses additional joint representation parameters for the representation transformation.

5. Apparatus of claim 3 , wherein the joint representation is a mid/side representation, and wherein the representation transformer is configured to operate based on the following equation:
leftTile=0.5*(midTile+sideTile)
rightTile=0.5*(midTile−sideTile)

wherein leftTile and rightTile are the separate representation for the second spectral portion, and wherein midTile and sideTile are the joint representation for the second spectral portion.

6. Apparatus of claim 3 , wherein the joint representation is a representation comprising an additional prediction coefficient, and wherein the representation transformer is configured to operate based on the following equation:
sideTile[ k ]=sideTile[ k ]−predictionCoeff·midTile[ k]

leftTile[ k ]=midTile[ k ]+sideTile[ k]
rightTile[ k ]=midTile[ k ]−sideTile[ k]

when a prediction direction is from mid to side, or
midTile[ k ]=midTile[ k ]−predictionCoeff·sideTile[ k]

leftTile[ k ]=midTile[ k ]−sideTile[ k]

rightTile[ k ]=midTile[ k ]+sideTile[ k]

when a prediction direction is indicated from side to mid,
wherein leftTile and rightTile are the separate representation for the second spectral portion, and wherein midTile and sideTile are the joint representation for the second spectral portion, and wherein predictionCoefficient is the additional prediction coefficient.

7. Apparatus of claim 1 ,
wherein the parametric data for the second set of second spectral portions is separately given for each channel of the two-channel representation, and
wherein the frequency regenerator is configured for transforming the parametric data for the second spectral portion into a joint representation for the second spectral portion and for applying the parametric data to a joint representation of the first spectral portion, when the two-channel identification identifies the joint representation for the second spectral portion.

8. Apparatus of claim 1 , wherein the second spectral portions correspond to frequency bands, and wherein the two-channel identification is an array of flags, one flag for each frequency band, and wherein the parametric decoder is configured to check, whether the flag is set or not and to control the frequency regeneration in accordance with the flag to use either a first two channel representation or a second two channel representation of the first spectral portion of the encoded two-channel signal.

9. Apparatus of claim 1 , wherein the parametric decoder is configured to provide a further two-channel identification for the first set of first spectral portions indicating either a first or a second different two-channel representation for the first spectral portion, and
wherein the apparatus is configured for decoding the second two-channel representation as indicated by the two-channel identification for the first spectral portion, and
wherein the frequency regenerator is configured for transforming the second two-channel representation into the first two-channel representation subsequent to a core decoding.

10. Apparatus of claim 1 , further comprising a combiner for combining the first set of first spectral portions generated by the audio processor and the reconstructed second spectral portion generated by the frequency regenerator to acquire the decoded two-channel signal.

11. Apparatus of claim 1 ,
wherein the parametric decoder is configured for additionally providing, for the second spectral portion, a source band identification indicating a specific first spectral portion to be used for regenerating the second spectral portion, and
wherein the frequency regenerator is configured to regenerate the second spectral portion using the first spectral portion identified by the source band identification.

12. Apparatus of claim 1 , wherein the audio processor is configured to decode the first set of first spectral portions in accordance with a further two-channel identification for the first set of the first spectral portions the further two-channel identification identifying either a first two-channel representation for a first spectral portion of the first set of first spectral portions or a second different two-channel representation for the first spectral portion of the first set of first spectral portions, and to transform the first set of first spectral portions so that a first two-channel representation of the first spectral portion of the first set of first spectral portions and a second two-channel representation of the first spectral portion of the first set of first spectral portions are acquired, and
wherein the frequency regenerator is configured to use either the first two-channel representation of the first set of first spectral portions or the second two-channel representation of the first set of first spectral portions

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

• G10L19/0204

  using subband decomposition · CPC title

• G10L19/025

  Detection of transients or attacks for time/frequency resolution switching · CPC title