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

Patent metadata

Field	Value
Publication number	US-11257505-B2
Application number	US-202017094791-A
Country	US
Kind code	B2
Filing date	Nov 10, 2020
Priority date	Jul 22, 2013
Publication date	Feb 22, 2022
Grant date	Feb 22, 2022

Abstract

An apparatus for generating a decoded two-channel signal includes: an audio processor for decoding an encoded two-channel signal to obtain a first set of first spectral portions; a parametric decoder for providing parametric data for a second set of second spectral portions and a two-channel identification identifying either a first or a second different two-channel representation for the second spectral portions; and a frequency regenerator for regenerating a second spectral portion depending on a first spectral portion of the first set of first spectral portions, the parametric data for the second portion and the two-channel identification for the second portion.

First claim

The invention claimed is:

1. An audio decoder for generating a decoded two-channel signal, the audio decoder comprising:
a parametric decoder configured for providing parametric data for a second set of second spectral portions and configured for providing a two-channel identification for a second spectral portion of the second set of second spectral portions identifying either a first two-channel representation for the second spectral portion of the second set of second spectral portions or a second different two-channel representation for the second spectral portion of the second set of second spectral portions; and
a frequency regenerator configured 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, wherein the decoded two-channel signal comprises the regenerated second spectral portion of the second set of second spectral portions.

2. The audio decoder of claim 1 , wherein the two-channel identification identifies either a separate processing of two channels of the encoded two-channel signal or 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 of the second set of second spectral portions for a first channel of the two channels and the second spectral portion of the second set of second spectral portions for a second channel of the two channels using the first portion of the first set of first spectral portions of the first channel and the first portion of the first set of first spectral portions of the second channel, wherein the first portion of the first set of first spectral portions of the first channel and the first portion of the first set of first spectral portions of the second channel are in the two-channel representation identified by the two-channel identification for the second spectral portion of the second set of second spectral portions.

3. The audio decoder of claim 1 , wherein the two-channel identification identifies either a separate processing of two channels of the encoded two-channel signal or a joint processing of the two channels of the encoded two-channel signal,
wherein the frequency regenerator is configured for regenerating a joint representation of the two channels of the second spectral portion of the second set of second spectral portions as identified by the two-channel identification, and
wherein the frequency regenerator further comprises a representation transformer configured for transforming the joint representation of the second spectral portion of the second set of second spectral portions into a separate representation for the second spectral portion of the second set of second spectral portions.

4. The audio decoder of claim 3 , wherein the representation transformer is configured for using additional joint representation parameters for the transforming the joint representation of the second spectral portion of the second set of second spectral portions.

5. The audio decoder of claim 3 , wherein the joint representation is a mid/side representation, and wherein the representation transformer is configured for operating 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 of the second set of second spectral portions, and wherein midTile and sideTile are the joint representation for the second spectral portion of the second set of second spectral portions.

6. The audio decoder of claim 3 , wherein the joint representation is a representation comprising an additional prediction coefficient, and wherein the representation transformer is configured for operating 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 indicated from mid to side, or
wherein the representation transformer is configured for operating based on the following equation
midTile1[ k ]=midTile[ k ]−predictionCoeff·sideTile[ k ]

leftTile[ k ]=midTile1[ k ]−sideTile[ k ]

rightTile[ k ]=midTile1[ 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 of the second set of second spectral portions, and wherein midTile and sideTile are the joint representation for the second spectral portion of the second set of second spectral portions, and wherein predictionCoefficient is the additional prediction coefficient.

7. The audio decoder 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 of the second set of second spectral portions into a joint representation for the second spectral portion of the second set of second spectral portions and for applying the parametric data to a joint representation of the first spectral portion of the first set of first spectral portions, when the two-channel identification identifies the joint representation for the second spectral portion of the second set of second spectral portions.

8. The audio decoder of claim 1 , wherein the second spectral portions of the second set of second spectral portions correspond to frequency bands, and wherein the two-channel identifications for the second spectral portions of the second set of second spectral portions comprise an array of flags, one flag for each frequency band, and wherein the parametric decoder is configured for checking, whether the flag for the frequency band is set or not and for controlling the regenerating the second spectral portion of the second set of second spectral portions in accordance with the flag to use either a first two channel representation of a first spectral portion of the first set of first spectral portions or a second two channel representation of the first spectral portion of the first set of first spectral portions of the encoded two-channel signal.

9. The audio decoder of claim 1 , wherein the parametric decoder is configured for providing a further two-channel identification for the first set of first spectral portions indicating either a first two-channel representation for the 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
wherein an audio processor is configured for decoding the second two-channel representation for the first spectral portion of the first set of first spectral portions as indicated by the two-channel identification for the first spectral portion of the first set of first spectral portions, and
wherein the frequency regenerator is configured for transforming the second two-channel representation for the first spectral portion of the first set of first spectral portions into the first two-channel representation for the first spectral portion of the first set of first spectral portions subsequent to the decoding the second two-channel representation for the firs

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