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Multi-channel audio signal processing

An audio signal, multi-channel technology, applied in the direction of two-channel system, electrical components, transmission system, etc., can solve the problem of how to operate without description, achieve the effect of reducing noise and improving the output sound quality

Inactive Publication Date: 2013-11-06
NXP BV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Third, the system does not describe how to operate when the channel conditions are poor or very good

Method used

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  • Multi-channel audio signal processing
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Examples

Experimental program
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Effect test

no. 1 example

[0056] figure 2 A block diagram of a first embodiment of a signal processing device 200 according to the invention is shown in which an improved difference signal d is calculated under noisy signal conditions. The noisy sum signal s and the noisy difference signal d are input to the parameter estimation module 201 . Compute two gains g based on the signal power of the sum and difference signals and the cross-correlation of the sum and difference signals s and g sd . These two gains are used to define the following from the sum signal s and the decorrelated version of the sum signal s d to estimate the transfer function of the predicted signal d'.

[0057] d'=g s ·s+g sd ·s d

[0058] Compared to the way the difference signal is computed in WO 2008 / 087577, the above relation includes an additional decorrelated signal component term g sd ·s d .

[0059] The gain g can be calculated from the powers of the sum signal s and the difference signal d and the unnormalized c...

no. 2 example

[0069] According to the second embodiment, the signal processing apparatus of the first embodiment can be extended with noise information which can be obtained from the difference signal d. A trade-off can be made between signal properties corresponding to the stereo image and signal properties corresponding to the noise level of the signal, the two properties being separable to a certain extent.

[0070] Figure 3a yes figure 1 A reproduction of , showing a schematic representation of the power spectral density (PSD) of the input FM-multiplexed signal. The input signals include a baseband sum signal 301 (between 0 and 15 kHz), a 19 kHz pilot tone 302, and a double sideband suppressed carrier modulated difference signal 303 (between 23 and 53 kHz). There is also a noise signal 304 which increases with increasing frequency.

[0071] Effectively, the difference signal 303 is available twice, once in the frequency range from 23 to 38 kHz and once in the frequency range from 38...

no. 3 example

[0083] According to a third embodiment, the device of the second embodiment may be adapted to also allow scaling to be transparent to low noise levels. Figure 5 A signal processing device 500 according to the third embodiment is shown. In addition to the solution of the second embodiment of obtaining the SNNR estimate, in the third embodiment, the original difference signal d can also be used in another way. If the SNNR is above a certain threshold (eg 15dB), it is advantageous to use the raw difference signal instead of the synthesized difference signal d', the acquisition of which was described above in relation to the first and second embodiments. A hybrid scheme can be implemented where, for each T / F layer, a better quality can be obtained according to the actual SNNR.

[0084] In this embodiment as well as in the second embodiment, a metric needs to be used to control the behavior of the parameter estimation module 201 . This metric does not have to be the SNNR estimat...

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Abstract

The invention relates to multi-channel audio signal processing, in particular to a method of processing a multi-channel audio signal and to a signal processing device. A method of processing a multi-channel audio signal is disclosed, comprising the steps of: receiving an input sum signal (s) representing a sum of a first audio signal and a second audio signal; receiving an input difference signal (d) representing a difference between the first and second audio signals; decorrelating the sum signal to provide a decorrelated sum signal (s d ); calculating a first gain (g s ) from a cross-correlation of the sum and difference signals (s,d) and the power of the sum signal; calculating a second gain (g sd ) from a cross-correlation of the sum and difference signals (s,d) and the power of the sum and difference signals; calculating an output difference signal (d') from a sum of the first gain (g s ) applied to the sum signal (s) and the second gain (g sd ) applied to the decorrelated sum signal (s d ); and providing an output stereo audio signal (l,r) from a combination of the output difference signal (d') and the input sum signal (s).

Description

technical field [0001] The invention relates to multi-channel audio signal processing, in particular to a method for processing multi-channel audio signals and a signal processing device. Background technique [0002] FM radio was invented in the 1940s and expanded for stereo broadcasting in the 1960s. Such as figure 1 Schematically shown, the demodulated FM stereo signal includes a mono audio signal (L+R), a 19kHz pilot tone and a stereo difference signal (stereo difference signal) (L-R) modulated on a 38kHz subcarrier. From the mono sum signal 101 and the difference signal 103 the left and right channels are reconstructed. Although the received FM signal includes white noise, the demodulated signal includes components (denoted as noise signal 104) that increase linearly with frequency. Since the mono audio signal 101 exists in the low frequency region (below 15kHz), the mono audio signal 101 contains a substantially lower noise level than the difference signal 103, whic...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04B1/10H04B1/16
CPCH04S1/00
Inventor 埃里克·高苏努斯·彼突斯·舒伊斯塞巴斯蒂安·德波恩特
Owner NXP BV
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