Advanced stereo coding based on a combination of adaptively selectable left/right or mid/side stereo coding and of parametric stereo coding

Patent metadata

Field	Value
Publication number	US-11017785-B2
Application number	US-201916369728-A
Country	US
Kind code	B2
Filing date	Mar 29, 2019
Priority date	Mar 17, 2009
Publication date	May 25, 2021
Grant date	May 25, 2021

Abstract

The application relates to audio encoder and decoder systems. An embodiment of the encoder system comprises a downmix stage for generating a downmix signal and a residual signal based on a stereo signal. In addition, the encoder system comprises a parameter determining stage for determining parametric stereo parameters such as an inter-channel intensity difference and an inter-channel cross-correlation. Preferably, the parametric stereo parameters are time- and frequency-variant. Moreover, the encoder system comprises a transform stage. The transform stage generates a pseudo left/right stereo signal by performing a transform based on the downmix signal and the residual signal. The pseudo stereo signal is processed by a perceptual stereo encoder. For stereo encoding, left/right encoding or mid/side encoding is selectable. Preferably, the selection between left/right stereo encoding and mid/side stereo encoding is time- and frequency-variant.

First claim

The invention claimed is:

1. An audio signal processing device for encoding a stereo signal to a bitstream signal, the audio signal processing device comprising one or more components that:
generate an intermediate stereo signal and stereo SBR parameters in response to the stereo signal;
generate a downmix signal, a residual signal, and one or more parametric stereo parameters based on the intermediate stereo signal, wherein the residual signal indicates an error associated with representing the intermediate signal by the downmix signal and the one or more parametric stereo parameters;
generate, in a frequency-variant or frequency-invariant manner, a first signal and a second signal based on either:
a sum of the downmix signal and the residual signal and a difference of the downmix signal and the residual signal; or
the downmix signal and the residual signal;

generating an encoded stereo signal by perceptual encoding the first signal and the second signal; and
generating the bitstream signal by combining the stereo SBR parameters, the parametric stereo parameters, and the encoded stereo signal.

2. The audio signal processing device of claim 1 , wherein perceptual encoding comprises:
generating, in a frequency-variant or frequency-invariant manner, the encoded stereo signal by performing either:
left/right perceptual encoding of the first signal and the second signal; or mid/side perceptual encoding of the first signal and the second signal.

3. The audio signal processing device of claim 2 , wherein perceptual encoding comprises selecting, in a frequency-variant or frequency-invariant manner and based on the first signal and the second signal, between either:
left/right perceptual encoding of the first signal and the second signal; or
mid/side perceptual encoding of the first signal and the second signal.

4. The audio signal processing device of claim 2 , wherein left/right perceptual encoding of the first signal and the second signal is performed for some frequency bands, and mid/side perceptual encoding of the first signal and the second signal is performed for other frequency bands.

5. A audio signal processing device for decoding a bitstream signal including stereo SBR parameters and one or more parametric stereo parameters to a stereo signal, the audio signal processing device comprising one or more components that:
generate a first signal and a second signal by perceptual decoding the bitstream signal;
generate, in a frequency-variant or frequency-invariant manner, a downmix signal and a residual signal based on either:
a sum of the first signal and of the second signal and a difference of the first signal and of the second signal; or
the first signal and the second signal;

generate an intermediate stereo signal by performing an upmix operation in response to the downmix signal, the residual signal, and the parametric stereo parameters, wherein the residual signal indicates an error associated with representing the first signal and the second signal by the downmix signal and the parametric stereo parameters; and
generate the stereo signal by performing a stereo SBR decoding operation in response to the intermediate stereo signal and the stereo SBR parameters.

6. The audio signal processing device of claim 5 , wherein perceptual decoding the bitstream signal comprises:
generating, in a frequency-variant or frequency-invariant manner, the first signal and the second signal by performing either:
left/right perceptual decoding of the bitstream signal; or
mid/side perceptual decoding of the bitstream signal.

7. The audio signal processing device of claim 6 , wherein left/right perceptual decoding of the bitstream signal is performed for some frequency bands, and mid/side perceptual decoding of the bitstream signal is performed for other frequency bands.

8. The audio signal processing device of claim 5 , wherein the parametric stereo parameters comprise:
a frequency-variant or a frequency-invariant parameter indicating an inter-channel intensity difference; and
a frequency-variant or a frequency-invariant parameter indicating an inter-channel cross-correlation.

9. A method, performed by an audio signal processing device, for decoding a bitstream signal including stereo SBR parameters and one or more parametric stereo parameters to a stereo signal, the method comprising:
generating a first signal and a second signal by perceptual decoding the bitstream signal;
generating, in a frequency-variant or frequency-invariant manner, a downmix signal and a residual signal based on either:
a sum of the first signal and of the second signal and based on a difference of the first signal and of the second signal; or
the first signal and the second signal;

generating an intermediate stereo signal by performing an upmix operation in response to the downmix signal, the residual signal, and the parametric stereo parameters, wherein the residual signal indicates an error associated with representing the first signal and the second signal by the downmix signal and the parametric stereo parameters; and
generating the stereo signal by performing a stereo SBR decoding operation in response to the intermediate stereo signal and the stereo SBR parameters;
wherein the method is performed, at least in part, by one or more components of the audio signal processing device.

10. A non-transitory computer readable storage medium comprising a sequence of instructions, wherein, when executed by an audio signal processing device, the sequence of instructions causes the audio signal processing device to perform the method of claim 9 .

Assignees

• Dolby Int Ab

Inventors

• Purnhagen Heiko
• Carlsson Pontus
• Kjoerling Kristofer

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

• H04S3/02

  of the matrix type, i.e. in which input signals are combined algebraically, e.g. after having been phase shifted with respect to each other · CPC title

• G10L19/18

  Vocoders using multiple modes · CPC title

• G10L19/002 Primary

  Dynamic bit allocation (for perceptual audio coders G10L19/032) · CPC title

• H04S2400/03

  Aspects of down-mixing multi-channel audio to configurations with lower numbers of playback channels, e.g. 7.1 -> 5.1 (H04S2400/01 takes precedence) · CPC title