US 7,382,886 B2 · Efficient and scalable parametric stereo coding for low bitrate audio coding applications

Abstract

The present invention provides improvements to prior art audio codecs that generate a stereo-illusion through post-processing of a received mono signal. These improvements are accomplished by extraction of stereo-image describing parameters at the encoder side, which are transmitted and subsequently used for control of a stereo generator at the decoder side. Furthermore, the invention bridges the gap between simple pseudo-stereo methods, and current methods of true stereo-coding, by using a new form of parametric stereo coding. A stereo-balance parameter is introduced, which enables more advanced stereo modes, and in addition forms the basis of a new method of stereo-coding of spectral envelopes, of particular use in systems where guided HFR (High Frequency Reconstruction) is employed. As a special case, the application of this stereo-coding scheme in scalable HFR-based codecs is described.

Claims34

Dependent claims

A method for coding of stereo properties of a first channel and a second channel of an input signal, the input signal being a two channel signal or a multichannel signal having the first channel and the second channel, comprising:

calculating a stereo width parameter from the first channel and the second channel, wherein the stereo-width parameter represents a degree of similarity between the first channel and the second channel, and wherein the stereo width-parameter is a value from a finite set of values covering a range between a mono situation and a wide stereo situation between the first channel and the second channel;
calculating a balance-parameter, wherein the balance-parameter represents a localization in a stereo field of the first channel and the second channel, and
transmitting or storing the width parameter and the balance parameter so that a decoder, when receiving the width parameter and the balance parameter is adapted to generate a first output channel and a second output channel of an output signal, the output signal being a two channel output signal or a multichannel output signal having the first output channel and the second output channel, using the stereo width-parameter to control a stereo-width between the first output channel and the second output channel of the output signal and using the balance-parameter to control a localization in the stereo field between the first output channel and the second output channel of the output signal.

A method for synthesizing a first output channel and a second output channel of an output signal, the output signal being a two channel output signal or a multichannel output signal having the first output channel and the second output channel, using a stereo width-parameter representing a degree of similarity between a first channel and a second channel of an original signal, the original signal being a two channel signal or a multichannel signal having the first channel and the second channel, the stereo width-parameter being a value from a finite set of values covering a range between a mono situation and a wide stereo situation between the first channel and the second channel of the original signal, and a balance-parameter, representing a localization in a stereo field of the first channel and the second channel of the original signal, and a mono signal derived from the first channel and the second channel of the original signal, comprising:

parametric stereo decoding for generating a synthesized stereo output signal from the mono signal by using the stereo width-parameter to control a stereo-width between the first output channel and the second output channel of the output signal, and using the balance-parameter to control a localization in the stereo field between the first output channel and the second output channel of the output signal.

Dependencies are inferred from the claim text.

Efficient and scalable parametric stereo coding for low bitrate audio coding applications

Life of this patent

Efficient and scalable parametric stereo coding for low bitrate audio coding applications

Life of this patent

Abstract

Claims34