Dolby International Ab

Microsoft Technology Licensing, LLC

Skype Limited

Dolby Laboratories Licensing Corporation

Fraunhofer-Gesellschaft Zur Foerderung Der Angewandten Forschung E.V.

Pontus Carlsson

Heiko Purnhagen

Lars Villemoes

Kristofer Kjoerling

David Yuheng Zhao

Andrei Jefremov

Sergei Nikiforov

Magnus Hemmendorff

Sergey Silkin

Konrad Hofbauer

Michael Schug

Mattias Nilsson

Per Hedelin

Sergey Sablin

Ming-Chieh Lee

Leif Jonas Samuelsson

Amy Lu

Christopher Owen

Sascha Disch

Christian Helmrich

Johannes Hilpert

Nikolaus Rettelbach

Bernd Edler

Matthias Neusinger

Kristofer Kjörling

Renat Vafin

Sören Vang Andersen

Julien Robillard

Purnhagen Heiko

Jonas Samuelsson

Methods and systems for advanced stereo processing of an audio signal are disclosed. The methods and systems include selecting a coding mode of either transform coding or linear predictive coding and performing advanced stereo processing when in the selected coding mode. Both encoding and decoding operations are provided.

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

The invention provides methods and devices for stereo encoding and decoding using complex prediction in the frequency domain. In one embodiment, a decoding method, for obtaining an output stereo signal from an input stereo signal encoded by complex prediction coding and comprising first frequency-domain representations of two input channels, comprises the upmixing steps of:

MDCT-based complex prediction stereo coding

Selectable linear predictive or transform coding modes with advanced stereo coding

Methods and systems encoding a stereo audio signal having an original left channel and an original right channel are disclosed. The method includes generating a downmix signal and a residual signal based on the stereo audio signal and determining one or more stereo parameters based on the stereo audio signal. The residual signal covers only a part of an audio frequency range of the stereo signal, and the one or more stereo parameters describing a stereo image of the stereo audio signal. The method further includes analyzing the stereo audio signal and selecting, based on the analyzing, left/right perceptual encoding or mid/side perceptual encoding in a time variant manner.

Audio encoder with selectable L/R or M/S coding

The invention provides methods and devices for stereo encoding and decoding using complex prediction in the frequency domain. In one embodiment, a decoding method, for obtaining an output stereo signal from an input stereo signal encoded by complex prediction coding and comprising first frequency-domain representations of two input channels, comprises the upmixing steps of: (i) computing a second frequency-domain representation of a first input channel; and (ii) computing an output channel on the basis of the first and second frequency-domain representations of the first input channel, the first frequency-domain representation of the second input channel and a complex prediction coefficient. The upmixing can be suspended responsive to control data.

The invention provides methods and devices for outputting a stereo audio signal having a left channel and a right channel. The apparatus includes a demultiplexer, decoder, and upmixer. The upmixer is configured operate either in a prediction mode or a non-prediction mode based on a parameter encoded in the audio bitstream.

Audio upmixer operable in prediction or non-prediction mode

Methods and systems encoding a stereo audio signal having a left channel and a right channel are disclosed. The system includes a downmixer for generating a downmix signal and a residual signal from the stereo audio signal in selected frequency bands representing only part of a used audio frequency range of the stereo audio signal, and a decision module for selecting, in a time variant manner, either left/right perceptual encoding or mid/side perceptual encoding. The system also includes a parameter estimator for estimating stereo parameters for reconstructing a stereo image of a portion of the stereo audio signal, and a perceptual encoder for performing either left/right perceptual encoding or mid/side perceptual encoding based on the selecting to generate an encoded output signal. Finally, the system includes a bitstream generator for creating a bitstream signal comprising the encoded output signal.

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.

Growing community of inventors

Bromma, Sweden

Pontus Carlsson