Perceptual weighting device and method for efficient coding of wideband signals

Abstract

A perceptual weighting device for producing a perceptually weighted signal in response to a wideband signal comprises a signal pre-emphasis filter, a synthesis filter calculator, and a perceptual weighting filter. The signal pre-emphasis filter enhances the high frequency content of the wideband signal to thereby produce a pre-emphasized signal. The signal pre-emphasis filter has a transfer function of the form: P(z)=1−μz⁻¹, wherein μ is a pre-emphasis factor having a value located between 0 and 1. The synthesis filter calculator is responsive to the pre-emphasized signal for producing synthesis filter coefficients. Finally, the perceptual weighting filter processes the pre-emphasized signal in relation to the synthesis filter coefficients to produce the perceptually weighted signal. The perceptual weighting filter has a transfer function, with fixed denominator, of the form: W(z)=A(z/γ₁)/(1−γ₂z⁻¹) where 0<γ₂<γ₁≦1.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a perceptual weighting device and method for producing a perceptually weighted signal in response to a wideband signal (0-7000 Hz) in order to reduce a difference between a weighted wideband signal and a subsequently synthesized weighted wideband signal. [0003] 2. Brief Description of the Prior Art [0004] The demand for efficient digital wideband speech / audio encoding techniques with a good subjective quality / bit rate trade-off is increasing for numerous applications such as audio / video teleconferencing, multimedia, and wireless applications, as well as Internet and packet network applications. Until recently, telephone bandwidths filtered in the range 200-3400 Hz were mainly used in speech coding applications. However, there is an increasing demand for wideband speech applications in order to increase the intelligibility and naturalness of the speech signals. A bandwidth in the rang...

AI Technical Summary

Benefits of technology

[0013] An object of the present invention is therefore to provide a perceptual weighting device and method adapted to wideband signals, using a modifi

Problems solved by technology

Some difficulties arise when applying the telephone-band optimized CELP model to wideband signals, and additional features need to be added to the model in order to obtain high quality wideband signals.

Wideband signals exhibit a much wider dynamic range compared to telephone-band signals, which results in precision problems when a fixed-point implementation of the algorithm is required (which is essential in wireless applications).

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