US 5,812,971 A · Enhanced joint stereo coding method using temporal envelope shaping

Abstract

A method and apparatus for performing joint stereo coding of multi-channel audio signals using intensity stereo coding techniques. In particular, predictive filtering techniques are applied to the spectral coefficient data, thereby preserving the time structure of the output signal of each channel, while maintaining the benefit of the high bit rate savings offered by intensity stereo coding. In one illustrative embodiment of the invention, the input signal is decomposed into spectral coefficients by a high-resolution filterbank/transform; the time-dependent masking threshold of the signal is estimated using a perceptual model; a filter performing linear prediction in frequency is applied at the filterbank outputs for each channel; intensity stereo coding techniques are applied for coding both residual signals into one carrier signal; the spectral values of the carrier signal are quantized and coded according to the precision corresponding to the masking threshold estimate; and all relevant information (i.e., the coded spectral values, intensity scaling data and prediction filter data for each channel, as well as the additional side information) is packed into a bitstream and transmitted to the decoder.

Claims24

Dependent claims

A method of performing joint stereo coding of a multi-channel audio signal to generate an encoded signal, the method comprising the steps of:

(a) performing a spectral decomposition of a first audio channel signal into a plurality of first spectral component signals;
(b) generating a first prediction signal representative of a prediction of one of said first spectral component signals, said prediction based on one or more other ones of said first spectral component signals;
(c) comparing the first prediction signal with said one of said first spectral component signals to generate a first prediction error signal;
(d) performing a spectral decomposition of a second audio channel signal into a plurality of second spectral component signals;
(e) performing joint stereo coding of said one of said first spectral component signals and one of said second spectral component signals to generate a jointly coded spectral component signal, said coding based on the first prediction error signal;
and
(f) generating the encoded signal based on the jointly coded spectral component signal.

4 more elements

A method of decoding an encoded signal to generate a reconstructed multi-channel audio signal, the encoded signal comprising a joint stereo coding of an original multi-channel audio signal, the method comprising the steps of:

(a) performing joint stereo decoding of the encoded signal to generate a plurality of decoded channel signals, each decoded channel signal comprising a plurality of decoded spectral component prediction error signals;
(b) generating a first spectral component signal based on one or more of said spectral component prediction error signals comprised in a first one of said decoded channel signals;
(c) generating a first prediction signal representative of a prediction of a second spectral component signal, said prediction based on said first spectral component signal;
(d) generating the second spectral component signal based on the first prediction signal and on one or more of said spectral component prediction error signals comprised in the first one of said decoded channel signals;
and
(e) generating a first channel of the reconstructed multi-channel audio signal based on the first and second spectral component signals.

3 more elements

An encoder for performing joint stereo coding of a multi-channel audio signal to generate an encoded signal, the encoder comprising:

(a) a first filterbank which performs a spectral decomposition of a first audio channel signal into a plurality of first spectral component signals;
(b) a first prediction filter which generates a first prediction signal representative of a prediction of one of said first spectral component signals, said prediction filter responsive to one or more other ones of said first spectral component signals;
(c) a first comparator which compares the first prediction signal with said one of said first spectral component signals to generate a first prediction error signal;
(d) a second filterbank which performs a spectral decomposition of a second audio channel signal into a plurality of second spectral component signals;
(e) a joint stereo coder which performs joint stereo coding of said one of said first spectral component signals and one of said second spectral component signals to generate a jointly coded spectral component signal, said coding based on the first prediction error signal;
and
(f) a coder which generates the encoded signal based on the jointly coded spectral component signal.

4 more elements

A decoder for decoding an encoded signal to generate a reconstructed multi-channel audio signal, the encoded signal comprising a joint stereo coding of an original multi-channel audio signal, the method comprising:

(a) a joint stereo decoder which performs joint stereo decoding of the encoded signal to generate a plurality of decoded channel signals, each decoded channel signal comprising a plurality of decoded spectral component prediction error signals;
(b) means for generating a first spectral component signal based on one or more of said spectral component prediction error signals comprised in a first one of said decoded channel signals;
(c) a first prediction filter which generates a first prediction signal representative of a prediction of a second spectral component signal, said prediction based on said first spectral component signal;
(d) means for generating the second spectral component signal based on the first prediction signal and on one or more of said spectral component prediction error signals comprised in the first one of said decoded channel signals;
and
(e) a first filterbank which generates a first channel of the reconstructed multi-channel audio signal based on the first and second spectral component signals.

3 more elements

A storage medium having an encoded signal recording thereon, the encoded signal having been generated from a multi-channel audio signal by an encoding method comprising the steps of:

(a) performing a spectral decomposition of a first audio channel signal into a plurality of first spectral component signals;
(b) generating a first prediction signal representative of a prediction of one of said first spectral component signals, said prediction based on one or more other ones of said first spectral component signals;
(c) comparing the first prediction signal with said one of said first spectral component signals to generate a first prediction error signal;
(d) performing a spectral decomposition of a second audio channel signal into a plurality of second spectral component signals;
(e) performing joint stereo coding of said one of said first spectral component signals and one of said second spectral component signals to generate a jointly coded spectral component signal, said coding based on the first prediction error signal;
and
(f) generating the encoded signal based on the jointly coded spectral component signal.

4 more elements

Dependencies are inferred from the claim text.

Enhanced joint stereo coding method using temporal envelope shaping

Life of this patent

Enhanced joint stereo coding method using temporal envelope shaping

Life of this patent

Abstract

Claims24