Apparatus and method for generating a bandwidth extended signal

Abstract

An apparatus for generating a bandwidth extended signal from an input signal includes a patch generator and a combiner. The input signal is represented for first and second bands by first and second resolution data, respectively, the second resolution being lower than the first. The patch generator generates first and second patches from the first band of the input signal according to first and second patching algorithms, respectively. A spectral density of the second patch generated using the second patching algorithm is higher than a spectral density of a first patch generated using the first patching algorithm. The combiner combines both patches and the first band of the input signal to obtain the bandwidth extended signal. The apparatus scales the input signal according to the first and second patching algorithms or scales the first and second patches, so that the bandwidth extended signal fulfills a spectral envelope criterion.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is a continuation of copending International Application No. PCT / EP2009 / 004603 filed Jun. 25, 2009, and also claims priority to U.S. Application No. 61 / 079,849, filed Jul. 11, 2008, which is incorporated herein by reference in its entiretyThis application is a reissue of U.S. Pat. No 8,880,410, issued Nov. 4, 2014, which was filed as U.S. application Ser. No. 13 / 004,314 on Jan. 11, 2011, which is a continuation of copending International Application No. PCT / EP2009 / 004603 filed Jun. 25, 2009, which claims priority from U.S. Application No. 61 / 079,849, filed Jul. 11, 2008, which are each incorporated herein in its entirety by this reference.[0002]Embodiments according to the invention relate to audio signal processing and, in particular, to an apparatus and a method for generating a bandwidth extended signal from an input signal, an apparatus and a method for providing a bandwidth reduced signal based on an input signal and...

AI Technical Summary

Benefits of technology

This patent describes a method for extending the frequency range of an audio signal by combining two patches, one with low spectral density and another with high spectral density, that are generated based on the input signal. This approach allows for a good approximation of the original audio signal and results in a high-quality bandwidth extended signal. The use of a harmonic patching algorithm and a mixing patching algorithm ensures a better filling of missing frequency lines and gaps, improving the overall quality of the signal.

Problems solved by technology

However, the coding used for this, in particular when operating at lowest bit rates, can lead to an reduction of subjective audio quality which is often mainly caused by an encoder side induced limitation of the audio signal bandwidth to be transmitted.

In particular, filterbank calculations and patching in the filterbank domain may become a high computational effort.

Adding noise may fill the gaps, but the audio quality or subjective quality may not be increased sufficiently.

Images