Apparatus and method for generating a frequency enhanced signal using temporal smoothing of subbands

• US 10,354,665 B2
• Filed: 07/26/2017
• Issued: 07/16/2019
• Est. Priority Date: 01/29/2013
• Status: Active Grant

• Current Assignee: Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V.
• Original Assignee: Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V.
• Inventors: Disch, Sascha, Geiger, Ralf, Helmrich, Christian, Multrus, Markus, Schmidt, Konstantin
• Primary Examiner(s): Chawan, Vijay B
• Application Number:
  US15/660,899
• Publication Number:
  US 20170323651A1
• Time in Patent Office: 720 Days
• Field of Search: 704205, 704208, 704210, 704230, 704500-504, 704211, 704203, 375240, 381 731, 381 943
• CPC Class Codes: G10L 19/0204 using subband decomposition
• CPC Class Codes: G10L 19/032 Quantisation or dequantisation of spectral components
• CPC Class Codes: G10L 19/06 Determination or coding of the spectral characteristics, e.g. of the short-term prediction coefficients
• CPC Class Codes: G10L 19/12 the excitation function being a code excitation, e.g. in code excited linear prediction [CELP] vocoders
• CPC Class Codes: G10L 2019/0012 Smoothing of parameters of the decoder interpolation
• CPC Class Codes: G10L 2019/0016 Codebook for LPC parameters
• CPC Class Codes: G10L 21/038 using band spreading techniques
• CPC Class Codes: G10L 21/0388 Details of processing therefor
• CPC Class Codes: G10L 25/18 the extracted parameters being spectral information of each sub-band

Abstract

An apparatus for generating a frequency enhancement signal has: a signal generator for generating an enhancement signal from a core signal, the enhancement signal having an enhancement frequency range not included in the core signal, wherein a current time portion of the enhancement signal or the core signal has subband signals for a plurality of subbands; a controller for calculating the same smoothing information for the plurality of subband signals of the enhancement frequency range or the core signal, and wherein the signal generator is configured for smoothing the plurality of subband signals of the enhancement frequency range or the core signal using the same smoothing information.

Claims

1. Apparatus for generating a frequency enhancement audio signal, comprising:

a signal generator configured for generating the frequency enhancement audio signal from a core audio signal, the frequency enhancement audio signal comprising an enhancement frequency range not included in the core audio signal, wherein a current time portion of the frequency enhancement audio signal or the core audio signal comprises subband signals for a plurality of subbands; and

a controller configured for calculating the same smoothing information for the plurality of subband signals of the enhancement frequency range or the core audio signal in the current time portion,

wherein the signal generator is configured for smoothing the plurality of subband signals of the enhancement frequency range or the core audio signal in the current time portion using the same smoothing information, and

wherein one or more of the signal generator and the controller is implemented, at least in part, by one or more hardware elements of the apparatus.

2. Apparatus of claim 1,

wherein the same smoothing information is a single correction factor for the plurality of subband signals of the enhancement frequency range, and wherein the signal generator is configured to apply the single correction factor to the plurality of subband signals of the enhancement frequency range.

3. Apparatus in accordance with claim 1,

further comprising a filterbank or a provider configured for providing the plurality of subband signals of the core audio signal for a plurality of time-subsequent filterbank slots,

wherein the signal generator is configured to derive the plurality of subband signals of the enhancement frequency range for the plurality of time-subsequent filterbank slots using the plurality of subband signals of the core audio signal, and

wherein the controller is configured to calculate an individual smoothing information for each filterbank slot.

4. Apparatus in accordance with claim 1,

wherein the controller is configured to calculate a smoothing intensity control value based on the core audio signal or the frequency enhancement audio signal of the current time portion and one or more preceding time portions, and

wherein the controller is configured to calculate the same smoothing information using the smoothing intensity control value in such a way that the smoothing intensity varies dependent on a difference between an energy of the core audio signal or the frequency enhancement audio signal in the current time portion and an average energy in the core audio signal or the frequency enhancement audio signal of one or more preceding time portions.

5. Apparatus in accordance with claim 1,

wherein the controller is configured to calculate the same smoothing information based on the following equation:

6. Apparatus in accordance with claim 1, wherein the signal generator is configured for shaping the core audio signal or the frequency enhancement audio signal in addition to the smoothing the plurality of subband signals.

7. Apparatus of claim 6,

wherein the current time portion and at least one further time portion form a whole frame,

wherein the signal generator is configured for applying an identical shaping information for the whole frame, and wherein the signal generator is configured for smoothing using an individual smoothing information for the current time portion and another individual smoothing information for the at least one further time portion within the frame.

8. Apparatus in accordance with claim 1,

wherein the signal generator is configured for performing an energy limitation on the frequency enhancement audio signal or the core audio signal in order to make sure that a frequency enhanced signal obtained by a synthesis filterbank is so that an energy of a higher band is, at the most, equal to an energy in a lower band or greater than, at the most, by a predefined threshold of 3dB or less.

9. Apparatus of in accordance with claim 1,

wherein the signal generator is configured for mirroring a single subband signal of the core audio signal or the plurality of subband signals of the core audio signal when calculating the plurality of subband signals of the frequency enhancement audio signal.

10. Method of generating a frequency enhancement audio signal, comprising:

generating the frequency enhancement audio signal from a core audio signal, the frequency enhancement audio signal comprising an enhancement frequency range not included in the core audio signal, wherein a current time portion of the frequency enhancement audio signal or the core audio signal comprises subband signals for a plurality of subbands;

calculating the same smoothing information for the plurality of subband signals of the enhancement frequency range or the core audio signal in the current time portion, and

wherein the generating comprises smoothing the plurality of subband signals of the enhancement frequency range or the core audio signal in the current time portion using the same smoothing information, and

wherein one or more of the generating and the calculating is implemented, at least in part, by one or more hardware elements of an audio signal processing device.

11. System for processing an audio signals, comprising:

an encoder configured for generating an encoded core audio signal from the audio signal; and

an apparatus for generating a frequency enhancement audio signal, the apparatus comprising;

a signal generator configured for generating the frequency enhancement audio signal from a core audio signal derived from the encoded core audio signal, the frequency enhancement audio signal comprising an enhancement frequency range not included in the core audio signal, wherein a current time portion of the enhancement signal or the core audio signal comprises subband signals for a plurality of subbands; and

a controller configured for calculating the same smoothing information for the plurality of subband signals of the enhancement frequency range or the core audio signal in the current time portion,

wherein the signal generator is configured for smoothing the plurality of subband signals of the enhancement frequency range or the core audio signal using the same smoothing information, and

wherein one or more of the encoder, the signal generator and the controller is implemented, at least in part, by one or more hardware elements of the apparatus.

12. Method of processing an audio signal, comprising:

generating an encoded core audio signal from the audio signal; and

generating a frequency enhancement audio signal using a method of generating the frequency enhancement audio signal, the method of generating the frequency enhancement audio signal comprising;

generating the frequency enhancement audio signal from a core audio signal derived from the encoded core audio signal, the frequency enhancement audio signal comprising an enhancement frequency range not included in the core audio signal, wherein a current time portion of the frequency enhancement audio signal or the core audio signal comprises subband signals for a plurality of subbands;

calculating the same smoothing information for the plurality of subband signals of the enhancement frequency range or the core audio signal, and

wherein the generating comprises smoothing the plurality of subband signals of the enhancement frequency range or the core audio signal in the current time portion using the same smoothing information,

wherein one or more of the generating the encoded core audio signal, the generating the enhancement signal and the calculating is implemented, at least in part, by one or more hardware elements of an audio signal processing device.

13. A non-transitory digital storage medium having a computer program stored thereon to perform, when running on a computer, a method of generating a frequency enhancement audio signal, the method comprising:

generating the frequency enhancement audio signal from a core audio signal, the frequency enhancement audio signal comprising an enhancement frequency range not included in the core audio signal, wherein a current time portion of the frequency enhancement audio signal or the core audio signal comprises subband signals for a plurality of subbands;

calculating the same smoothing information for the plurality of subband signals of the enhancement frequency range or the core audio signal in the current time portion, and

wherein the generating comprises smoothing the plurality of subband signals of the enhancement frequency range or the core audio signal in the current time portion using the same smoothing information.

14. A non-transitory digital storage medium having a computer program stored thereon to perform, when running on a computer, a method of processing an audio signal, the method comprising:

generating an encoded core audio signal from the audio signal; and

generating a frequency enhancement audio signal using a method of generating the frequency enhancement audio signal, the method of generating the frequency enhancement audio signal comprising;

generating the frequency enhancement audio signal from a core audio signal derived from the encoded core audio signal, the frequency enhancement audio signal comprising an enhancement frequency range not included in the core audio signal, wherein a current time portion of the frequency enhancement audio signal or the core audio signal comprises subband signals for a plurality of subbands;

calculating the same smoothing information for the plurality of subband signals of the enhancement frequency range or the core audio signal in the current time portion, and

wherein the generating comprises smoothing the plurality of subband signals of the enhancement frequency range or the core audio signal in the current time portion using the same smoothing information.