Estimation of mixing factors to generate high-band excitation signal

• US 10,410,652 B2
• Filed: 05/23/2018
• Issued: 09/10/2019
• Est. Priority Date: 10/11/2013
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Atti, Venkatraman S., Krishnan, Venkatesh
• Primary Examiner(s): Hang, Vu B
• Application Number:
  US15/987,840
• Publication Number:
  US 20180268839A1
• Time in Patent Office: 475 Days
• CPC Class Codes: G10L 19/0208 Subband vocoders
• CPC Class Codes: G10L 19/087 using mixed excitation models, e.g. MELP, MBE, split band LPC or HVXC
• CPC Class Codes: G10L 21/0208 Noise filtering
• CPC Class Codes: G10L 21/0216 characterised by the method used for estimating noise
• CPC Class Codes: G10L 21/038 using band spreading techniques
• CPC Class Codes: G10L 25/78 Detection of presence or absence of voice signals switching of direction of transmission by voice frequency in two-way loud-speaking telephone systems H04M9/10

Abstract

A method includes generating a high-band residual signal based on a high-band portion of an audio signal. The method also includes generating a harmonically extended signal at least partially based on a low-band portion of the audio signal. The method further includes determining a mixing factor based on the high-band residual signal, the harmonically extended signal, and modulated noise. The modulated noise is at least partially based on the harmonically extended signal and white noise.

Claims

1. An apparatus comprising:

a receiver configured to receive an encoded bit-stream, the encoded bit-stream corresponding to an encoded version of an audio signal and including data representative of a mixing factor, wherein the mixing factor is determined based on an encoder-side high-band residual signal, an encoder-side first harmonically extended signal and an encoder-side first modulated noise, wherein an encoder-side high-band excitation signal is based on the encoder-side first harmonically extended signal and the encoder-side first modulated noise, wherein the encoder-side first modulated noise is at least partially based on the encoder-side first harmonically extended signal and an encoder-side white noise; and

a decoder coupled to the receiver, the decoder configured to;

generate a second harmonically extended signal at least partially based on a low-band excitation signal associated with the encoded bit-stream;

scale the second harmonically extended signal based on the mixing factor to generate a first scaled signal;

scale second modulated noise based on the mixing factor to generate a second scaled signal;

combine the first scaled signal and the second scaled signal to generate a high-band excitation signal; and

reconstruct the audio signal based on the high-band excitation signal, wherein the reconstructed audio signal is outputted via a speaker.

2. The apparatus of claim 1, wherein the decoder is further configured to estimate a low-band time-domain envelope based on the second harmonically extended signal.

3. The apparatus of claim 2, wherein the decoder is further configured to combine the low-band time-domain envelope with second white noise to generate the second modulated noise.

4. The apparatus of claim 1, wherein the

mixing factor is further based on low-band voicing parameter associated with the audio signal.

5. The apparatus of claim 1, wherein the mixing factor is based on an error signal between the encoder-side high-band residual, the encoder-side first harmonically extended signal, and the encoder-side first modulated noise.

6. The apparatus of claim 1, wherein the receiver and the decoder are integrated into a mobile device.

7. A method comprising:

receiving an encoded bit-stream at a speech decoder, the encoded bit-stream corresponding to an encoded version of an audio signal and including data representative of a mixing factor, wherein the mixing factor is determined based on an encoder-side high-band residual signal, an encoder-side first harmonically extended signal and an encoder-side first modulated noise, wherein an encoder-side high-band excitation signal is based on the encoder-side first harmonically extended signal and the encoder-side first modulated noise, wherein the encoder-side first modulated noise is at least partially based on the encoder-side first harmonically extended signal and an encoder-side white noise;

generating, at the speech decoder, a second harmonically extended signal at least partially based on a low-band excitation signal associated with the encoded bit-stream;

scaling, at the speech decoder, the second harmonically extended signal based on the mixing factor to generate a first scaled signal;

scaling, at the speech decoder, second modulated noise based on the mixing factor to generate a second scaled signal;

combining, at the speech decoder, the first scaled signal and the second scaled signal to generate a high-band excitation signal; and

reconstructing the audio signal based on the high-band excitation signal, wherein the reconstructed audio signal is outputted via a speaker.

8. The method of claim 7, further comprising estimating, at the speech decoder, a low-band time-domain envelope based on the second harmonically extended signal.

9. The method of claim 8, further comprising combining, at the speech decoder, the low-band time-domain envelope with second white noise to generate the second modulated noise.

10. The method of claim 7, wherein the

mixing factor is further based on low-band voicing parameter associated with the audio signal.

11. The method of claim 7, wherein the mixing factor is based on an error signal between the encoder-side high-band residual, the encoder-side first harmonically extended signal, and the encoder-side first modulated noise.

12. The method of claim 7, wherein the speech decoder is integrated into a mobile device.

13. A non-transitory computer-readable medium comprising instructions that, when executed by a processor within a speech decoder, cause the speech decoder to perform operations comprising:

receiving an encoded bit-stream, the encoded bit-stream corresponding to an encoded version of an audio signal and including data representative of a mixing factor, wherein the mixing factor is determined based on an encoder-side high-band residual signal, an encoder-side first harmonically extended signal and an encoder-side first modulated noise, wherein an encoder-side high-band excitation signal is based on the encoder-side first harmonically extended signal and the encoder-side first modulated noise, wherein the encoder-side first modulated noise is at least partially based on the encoder-side first harmonically extended signal and an encoder-side white noise;

generating a second harmonically extended signal at least partially based on a low-band excitation signal associated with the encoded bit-stream;

scaling the second harmonically extended signal based on the mixing factor to generate a first scaled signal;

scaling second modulated noise based on the mixing factor to generate a second scaled signal;

combining the first scaled signal and the second scaled signal to generate a high-band excitation signal; and

reconstructing the audio signal based on the high-band excitation signal, wherein the reconstructed audio signal is outputted via a speaker.

14. The non-transitory computer-readable medium of claim 13, wherein the operations further comprise estimating a low-band time-domain envelope based on the second harmonically extended signal.

15. The non-transitory computer-readable medium of claim 14, wherein the operations further comprise combining the low-band time-domain envelope with second white noise to generate the second modulated noise.

16. The non-transitory computer-readable medium of claim 13, wherein the

mixing factor is further based on low-band voicing parameter associated with the audio signal.

17. The non-transitory computer-readable medium of claim 13, wherein the mixing factor is based on an error signal between the encoder-side high-band residual, the encoder-side first harmonically extended signal, and the encoder-side first modulated noise.