Apparatus, method and computer program for generating a representation of a bandwidth-extended signal on the basis of an input signal representation using a combination of a harmonic bandwidth-extension and a non-harmonic bandwidth-extension

Patent metadata

Field	Value
Publication number	US-9697838-B2
Application number	US-99205110-A
Country	US
Kind code	B2
Filing date	Apr 1, 2010
Priority date	Apr 2, 2009
Publication date	Jul 4, 2017
Grant date	Jul 4, 2017

Abstract

An apparatus for generating a representation of a bandwidth-extended signal on the basis of an input signal representation includes a phase vocoder configured to obtain values of a spectral domain representation of a first patch of the bandwidth-extended signal on the basis of the input signal representation. The apparatus also includes a value copier configured to copy a set of values of the spectral domain representation of the first patch, which values are provided by the phase vocoder, to obtain a set of values of a spectral domain representation of a second patch, wherein the second patch is associated with higher frequencies than the first patch. The apparatus is configured to obtain the representation of the bandwidth-extended signal using the values of the spectral domain representation of the first patch and the values of the spectral domain representation of the second patch.

First claim

The invention claimed is:

1. An apparatus for generating a representation of a bandwidth-extended signal on the basis of an input signal representation, the apparatus comprising:
a phase vocoder configured to acquire values of a spectral domain representation of a first patch of the bandwidth-extended signal on the basis of the input signal representation; and
a value copier configured to copy a set of values of the spectral domain representation of the first patch, which values are provided by the phase vocoder, to acquire a set of values of a spectral domain representation of a second patch, wherein the second patch is associated with higher frequencies than the first patch;
wherein the apparatus is configured to acquire the representation of the bandwidth-extended signal using the values of the spectral domain representation of the first patch and the values of the spectral domain representation of the second patch; and
wherein the apparatus is implemented using a hardware apparatus, or using a computer, or using a combination of a hardware apparatus and a computer.

2. The apparatus according to claim 1 , wherein the phase vocoder is configured to copy a set of magnitude values associated with a plurality of given frequency subranges of the input signal representation, to acquire a set of magnitude values associated with corresponding frequency subranges of the first patch,
wherein a pair of a given frequency subrange of the input signal representation and of a corresponding frequency subrange of the first patch cover a pair of a fundamental frequency and a harmonic of the fundamental frequency,
wherein the phase vocoder is configured to multiply phase values associated with the plurality of given frequency subranges of the input signal representation with a predetermined factor, to acquire a set of phase values associated with the corresponding frequency subranges of the first patch, and
wherein the value copier is configured to copy a set of values associated with a plurality of given frequency subranges of the first patch, to acquire a set of values associated with corresponding frequency subranges of the second patch, wherein the value copier is configured to leave phase values unchanged in the copying.

3. The apparatus according to claim 2 , wherein the value copier is configured to copy the values such that a common spectral shift between values of the first patch and corresponding values of the second patch is acquired.

4. The apparatus according to claim 1 , wherein the phase vocoder is configured to acquire the values of the spectral domain representation of the first patch such that the values of the spectral domain representation of the first patch represent a harmonically up-converted version of a fundamental frequency range of the input signal representation; and
wherein the value copier is configured to acquire the values of the spectral domain representation of the second patch such that the values of the spectral domain representation of the second patch represent a frequency-shifted version of the audio content of the first patch.

5. The apparatus according to claim 1 , wherein the apparatus is configured to receive input audio data,
to down-sample the input audio data, in order to acquire down-sampled audio data,
to window the down-sampled audio data, in order to acquire windowed input data,
to convert or transform the windowed input data into a spectral domain, in order to acquire the input signal representation in the form of a spectral domain representation,
to compute magnitude values α k and phase values φ k representing a frequency bin comprising index k of the input signal representation,
to use a plurality of magnitude values α k representing frequency bins comprising frequency bin indices k of the input signal representation, to acquire magnitude values α 2k representing frequency bins comprising frequency bin indices sk of the first patch,
when s is a stretching factor with s between 1.5 and 2.5, and
to copy and scale phase values φ k associated to frequency bins comprising frequency bin indices k of the input signal representation, to acquire copied and scaled phase values φ 2k =sφ k associated with frequency bins comprising frequency bin indices 2k of the first patch,
to copy values β k−iζ associated with frequency bins comprising frequency bin indices k−iζ of the spectral domain representation of the first patch, to acquire values β k of the spectral domain representation of the second patch,
to convert the representation of the bandwidth-extended signal into the time-domain, to acquire a time-domain representation, and
to apply a synthesis window to the time-domain representation.

6. The apparatus according to claim 1 , wherein the apparatus comprises a time-domain to spectral-domain converter configured to provide, as the input signal representation, values of a spectral-domain representation of an input audio signal, or of a pre-processed version of the input audio signal; and
wherein the apparatus comprises a spectral-domain-to-time-domain converter configured to provide a time-domain representation of the bandwidth-extended signal using values of the spectral-domain representation of the first patch and values of the spectral-domain representation of the second patch;
wherein the spectral-domain-to-time-domain converter is configured such that a number of different spectral values received by the spectral-domain-to-time-domain converter is larger than a number of different spectral values provided by the time-domain-to-spectral-domain converter, such that the spectral-domain-to-time-domain converter is configured to process a larger number of frequency bins than the time-domain-to-spectral-domain converter.

7. The apparatus according to claim 1 , wherein the apparatus comprises an analysis windower configured to window a time-domain input audio signal, to acquire a windowed version of the time-domain input audio signal, which forms the basis for acquiring the input signal representation in the form of a spectral domain representation; and
wherein the apparatus comprises a synthesis windower configured to window a portion of a time-domain representation of the bandwidth-extended signal, to acquire a windowed portion of the time-domain representation of the bandwidth-extended signal.

8. The apparatus according to claim 7 , wherein the apparatus is configured to process a plurality of temporally overlapping time-shifted portions of the time-domain input audio signal, to acquire a plurality of temporally overlapping time-shifted windowed portions of the time-domain representation of the bandwidth-extended signal,
wherein a time offset between temporally adjacent time-shifted portions of the time-domain input audio signal is smaller than or equal to one fourth of a window length of the analysis windower.

9. The apparatus according to claim 1 , wherein the apparatus comprises a transient information provider configured to provide an information indicating the presence of a transient in the input signal; and
wherein the apparatus comprises a first processing branch for providing a representation of a bandwidth-extended signal portion on the basis of a non-transient portion of the input signal representation and a second processing branch for providing a representation of a bandwidth-extended signal portion on the basis of a transient portion of the input signal representation;
wherein the second processing branch is configured to process a spectral-domain representation of the input signal comprising a higher spectral resolution than a spectral-domain representation of the input signal processed by the first processing branch.

10. The apparatus according t

Assignees

• Nagel Frederik
• Neuendorf Max
• Rettelbach Nikolaus
• Lecomte Jeremie
• Multrus Markus
• Grill Bernhard
• Disch Sascha
• Fraunhofer-Gesellschaft Zur Foerderung Der Angewandten Forschung E V

Inventors

• Nagel Frederik
• Neuendorf Max
• Rettelbach Nikolaus
• Lecomte Jeremie
• Multrus Markus
• Grill Bernhard
• Disch Sascha

Classifications

• G10L21/038

  using band spreading techniques · CPC title

• G10L19/18 Primary

  Vocoders using multiple modes · CPC title

• G10L19/008 Primary

  Multichannel audio signal coding or decoding using interchannel correlation to reduce redundancy, e.g. joint-stereo, intensity-coding or matrixing · CPC title

• G10L19/02

  using spectral analysis, e.g. transform vocoders or subband vocoders · CPC title

• G10L21/04 Primary

  Time compression or expansion · CPC title