Apparatus and method for stereo filling in multichannel coding

Patent metadata

Field	Value
Publication number	US-11727944-B2
Application number	US-202016918812-A
Country	US
Kind code	B2
Filing date	Jul 1, 2020
Priority date	Feb 17, 2016
Publication date	Aug 15, 2023
Grant date	Aug 15, 2023

Abstract

An apparatus for decoding an encoded multichannel signal of a current frame to obtain three or more current audio output channels is provided. A multichannel processor is adapted to select two decoded channels from three or more decoded channels depending on first multichannel parameters. Moreover, the multichannel processor is adapted to generate a first group of two or more processed channels based on the selected channels. A noise filling module is adapted to identify for at least one of the selected channels, one or more frequency bands, within which all spectral lines are quantized to zero, and to generate a mixing channel using, depending on side information, a proper subset of three or more previous audio output channels that have been decoded, and to fill the spectral lines of frequency bands, within which all spectral lines are quantized to zero, with noise generated using spectral lines of the mixing channel.

First claim

The invention claimed is:

1. Apparatus for decoding a previous encoded multichannel signal of a previous frame to acquire three or more previous audio output channels, and for decoding a current encoded multichannel signal of a current frame to acquire two or more current audio output channels,
wherein the apparatus comprises an interface, a channel decoder, a multichannel processor for generating the two or more current audio output channels, and a noise filling module,
wherein the channel decoder is adapted to decode the current encoded multichannel signal of the current frame to acquire a set of three or more decoded channels of the current frame,
wherein the multichannel processor is adapted to select a first selected pair of two decoded channels from the set of three or more decoded channels depending on first multichannel parameters of side information,
wherein the multichannel processor is adapted to generate a first group of two or more processed channels based on said first selected pair of two decoded channels to acquire an updated set of three or more decoded channels,
wherein, before the multichannel processor generates the first pair of two or more processed channels based on said first selected pair of two decoded channels, the noise filling module is adapted to identify for at least one of the two channels of said first selected pair of two decoded channels, one or more frequency bands, within which all spectral lines are quantized to zero, and to generate a mixing channel using two or more, but not all of the three or more previous audio output channels, and to fill the spectral lines of the one or more frequency bands, within which all spectral lines are quantized to zero, with noise generated using spectral lines of the mixing channel, wherein the noise filling module is adapted to select the two or more previous audio output channels that are used for generating the mixing channel from the three or more previous audio output channels depending on the side information.

2. An apparatus according to claim 1 ,
wherein the noise filling module is adapted to generate the mixing channel using exactly two previous audio output channels of the three or more previous audio output channels as the two or more of the three or more previous audio output channels;
wherein the noise filling module is adapted to select the exactly two previous audio output channels from the three or more previous audio output channels depending on the side information.

3. An apparatus according to claim 2 ,
wherein the noise filling module is adapted to generate the mixing channel using exactly two previous audio output channels based on the formula
D ch =( Ô 1 +Ô 2 )· d or based on the formula

D ch =( Ô 1 −Ô 2 )· d

wherein D ch is the mixing channel,
wherein Ô 1 is a first one of the exactly two previous audio output channels,
wherein Ô 2 is a second one of the exactly two previous audio output channels, being different from the first one of the exactly to previous audio output channels, and
wherein d is a real, positive scalar.

4. An apparatus according to claim 2 ,
wherein the noise filling module is adapted to generate the mixing channel using exactly two previous audio output channels based on the formula
Î ch =(cos α· Ô 1 +sin α· Ô 2 )· d or based on the formula

Î ch =(−sin α· Ô 1 +cos α· Ô 2 )· d

wherein Î ch is the mixing channel,
wherein Ô 1 is a first one of the exactly two previous audio output channels,
wherein Ô 2 is a second one of the exactly two previous audio output channels, being different from the first one of the exactly to previous audio output channels, and
wherein α is an rotation angle.

5. An apparatus according to claim 4 ,
wherein the side information is current side information being assigned to the current frame,
wherein the interface is adapted to receive previous side information being assigned to the previous frame, wherein the previous side information comprises a previous angle,
wherein the interface is adapted to receive the current side information comprising a current angle, and
wherein the noise filling module is adapted to use the current angle of the current side information as the rotation angle α, and is adapted to not use the previous angle of the previous side information as the rotation angle α.

6. An apparatus according to claim 2 , wherein the noise filling module is adapted to select the exactly two previous audio output channels from the three or more previous audio output channels depending on the first multichannel parameters.

7. An apparatus according to claim 2 ,
wherein the interface is adapted to receive the current encoded multichannel signal, and to receive the side information comprising the first multichannel parameters and second multichannel parameters,
wherein the multichannel processor is adapted to select a second selected pair of two decoded channels from the updated set of three or more decoded channels depending on the second multichannel parameters, at least one channel of the second selected pair of two decoded channels being one channel of the first pair of two or more processed channels, and
wherein the multichannel processor is adapted to generate a second group of two or more processed channels based on said second selected pair of two decoded channels to further update the updated set of three or more decoded channels.

8. An apparatus according to claim 7 ,
wherein, the multichannel processor is adapted to generate the first group of two or more processed channels by generating a first group of exactly two processed channels based on said first selected pair of two decoded channels;
wherein the multichannel processor is adapted to replace said first selected pair of two decoded channels in the set of three of more decoded channels by the first group of exactly two processed channels to acquire the updated set of three or more decoded channels;
wherein the multichannel processor is adapted to generate the second group of two or more processed channels by generating a second group of exactly two processed channels based on said second selected pair of two decoded channels, and
wherein the multichannel processor is adapted to replace said second selected pair of two decoded channels in the updated set of three of more decoded channels by the second group of exactly two processed channels to further update the updated set of three or more decoded channels.

9. An apparatus according to claim 8 ,
wherein the first multichannel parameters indicate two decoded channels from the set of three or more decoded channels;
wherein the multichannel processor is adapted to select the first selected pair of two decoded channels from the set of three or more decoded channels by selecting the two decoded channels being indicated by the first multichannel parameters;
wherein the second multichannel parameters indicate two decoded channels from the updated set of three or more decoded channels;
wherein the multichannel processor is adapted to select the second selected pair of two decoded channels from the updated set of three or more decoded channels by selecting the two decoded channels being indicated by the second multichannel parameters.

10. An apparatus according to claim 9 ,
where the apparatus is adapted to assign an identifier from a set of identifiers to each previous audio output channel of the three or more previous audio output channels, so that each previous audio output channel of the three or more previous audio output channels is assigned to exactly one identifier of the set of identifiers, and so that each identifier of the set of identifiers is assigned

Assignees

• Fraunhofer Ges Forschung

Inventors

• Dick Sascha
• Helmrich Christian
• Rettelbach Nikolaus
• Schuh Florian
• Fueg Richard
• Nagel Frederik

Classifications

• 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

• G10L19/028

  Noise substitution, i.e. substituting non-tonal spectral components by noisy source (comfort noise for discontinuous speech transmission G10L19/012) · CPC title

• G10L19/035

  Scalar quantisation · CPC title