Systems and methods of blind bandwidth extension

Patent metadata

Field	Value
Publication number	US-9524720-B2
Application number	US-201414334921-A
Country	US
Kind code	B2
Filing date	Jul 18, 2014
Priority date	Dec 15, 2013
Publication date	Dec 20, 2016
Grant date	Dec 20, 2016

Abstract

Systems and methods of performing blind bandwidth extension are disclosed. In an embodiment, a method includes determining, based on a set of low-band parameters of an audio signal, a first set of high-band parameters and a second set of high-band parameters. The method further includes generating a predicted set of high-band parameters based on a weighted combination of the first set of high-band parameters and the second set of high-band parameters.

First claim

What is claimed is:

1. A method comprising:
determining, based on multiple quantized low-band parameters and a set of low-band parameters of an audio signal, a first set of high-band parameters and a second set of high-band parameters, wherein a number of the multiple quantized low-band parameters is changed from frame to frame of the audio signal; and
predicting a set of high-band parameters based on a weighted combination of the first set of high-band parameters and the second set of high-band parameters.

2. The method of claim 1 , wherein the first set of high-band parameters and the second set of high-band parameters are determined based on weighted differences between the multiple quantized low-band parameters and the set of low-band parameters of the audio signal, wherein the number of the multiple quantized low-band parameters is adaptively changed from frame to frame of the audio signal, and further comprising extracting the set of low-band parameters from a signal received at a mobile device and converting the predicted set of high-band parameters from a non-linear domain to a linear domain to obtain a set of linear domain high-band parameters.

3. The method of claim 1 , wherein the set of low-band parameters are included in a narrowband bitstream received at a speech vocoder, and wherein the set of low-band parameters includes a first set of low-band parameters corresponding to a first frame of the audio signal.

4. The method of claim 3 , wherein determining the first set of high-band parameters and the second set of high-band parameters comprises:
selecting a first state from a plurality of states of a vectorization table based on the first set of low-band parameters; and
selecting a second state from the plurality of states of the vectorization table based on the first set of low-band parameters,
wherein the first state is associated with the first set of high-band parameters and the second state is associated with the second set of high-band parameters.

5. The method of claim 4 , further comprising:
selecting a particular state of the first state and the second state;
receiving a second set of low-band parameters corresponding to a second frame of the audio signal;
determining, based on entries in a transition probability matrix, bias values associated with transitions from the particular state to candidate states;
determining differences between the second set of low-band parameters and the candidate states based on the bias values; and
selecting a state corresponding to the second frame based on the differences.

6. The method of claim 3 , further comprising:
receiving a second set of low-band parameters corresponding to a second frame of the audio signal;
classifying the first set of low-band parameters as voiced or unvoiced;
classifying the second set of low-band parameters as voiced or unvoiced; and
selectively adjusting a gain parameter of the second frame based on a first classification of the first set of low-band parameters, a second classification of the second set of low-band parameters, a first energy value corresponding to the first set of low-band parameters, and a second energy value corresponding to the second set of low-band parameters.

7. The method of claim 6 , wherein selectively adjusting the gain parameter comprises, when the first set of low-band parameters is classified as voiced and the second set of low-band parameters is classified as voiced:
when the first energy value exceeds a threshold energy value and when the second energy value exceeds the threshold energy value, adjusting the gain parameter in response to the gain parameter exceeding a threshold gain.

8. The method of claim 6 , wherein selectively adjusting the gain parameter comprises, when the first set of low-band parameters is classified as unvoiced and the second set of low-band parameters is classified as voiced:
when the second energy value exceeds a threshold energy value and when the second energy value exceeds a first multiple of the first energy value, adjusting the gain parameter in response to the gain parameter exceeding a threshold gain.

9. The method of claim 6 , wherein selectively adjusting the gain parameter comprises, when the first set of low-band parameters is classified as voiced and the second set of low-band parameters is classified as unvoiced:
when the second energy value exceeds a threshold energy value and when the second energy value exceeds a second multiple of the first energy value, adjusting the gain parameter in response to the gain parameter exceeding a threshold gain.

10. The method of claim 6 , wherein selectively adjusting the gain parameter comprises, when the first set of low-band parameters is classified as unvoiced and the second set of low-band parameters is classified as unvoiced:
when the second energy value exceeds a third multiple of the first energy value and when the second energy value exceeds a threshold energy value, adjusting the gain parameter in response to the gain parameter exceeding a threshold gain.

11. The method of claim 1 , wherein the determining and the predicting are performed within a device that comprises a mobile communication device.

12. The method of claim 1 , wherein the determining and the predicting are performed within a device that comprises a fixed location communication unit.

13. An apparatus comprising:
a processor; and
a memory storing instructions executable by the processor to perform operations comprising:
determining, based on multiple quantized low-band parameters and a set of low-band parameters of an audio signal, a first set of high-band parameters and a second set of high-band parameters, wherein a number of the multiple quantized low-band parameters is changed from frame to frame of the audio signal; and
predicting a set of high-band parameters based on a weighted combination of the first set of high-band parameters and the second set of high-band parameters.

14. The apparatus of claim 13 , wherein the operations further comprise converting the predicted set of high-band parameters from a non-linear domain to a linear domain to obtain a set of linear domain high-band parameters, wherein the set of low-band parameters includes a first set of low-band parameters corresponding to a first frame of the audio signal, and wherein determining the first set of high-band parameters and the second set of high-band parameters comprises:
selecting a first state from a plurality of states of a vectorization table based on the first set of low-band parameters; and
selecting a second state from the plurality of states of the vectorization table based on the first set of low-band parameters,
wherein the first state is associated with the first set of high-band parameters and the second state is associated with the second set of high-band parameters.

15. The apparatus of claim 14 , wherein the operations further comprise:
selecting a particular state of the first state and the second state;
receiving a second set of low-band parameters corresponding to a second frame of the audio signal;
determining, based on entries in a transition probability matrix, bias values associated with transitions from the particular state to candidate states;
determining differences between the second set of low-band parameters and the candidate states based on the bias values; and
selecting a state corresponding to the second frame based on the differences.

16. The apparatus of claim 13 , wherein the set of low-band parameters includes a first set of low-band parameters corresponding to a first frame of the au

Assignees

• Qualcomm Inc

Inventors

• Li Sen
• Villette Stephane Pierre
• Sinder Daniel J
• Ramadas Pravin Kumar

Classifications

• G10L21/0388 Primary

  Details of processing therefor · CPC title

• G10L19/00 Primary

  Speech or audio signals analysis-synthesis techniques for redundancy reduction, e.g. in vocoders; Coding or decoding of speech or audio signals, using source filter models or psychoacoustic analysis (in musical instruments G10H) · CPC title

• G10L19/0017

  Lossless audio signal coding; Perfect reconstruction of coded audio signal by transmission of coding error (G10L19/24 takes precedence) · CPC title