Audio signal decoder and method for producing a scaled reconstructed audio signal

• US 8,200,496 B2
• Filed: 12/29/2008
• Issued: 06/12/2012
• Est. Priority Date: 12/29/2008
• Status: Active Grant

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola Mobility, Inc. (Lenovo Group Ltd.)
• Inventors: Ashley, James P., Mittal, Udar
• Primary Examiner(s): Opsasnick, Michael N
• Application Number:
  US12/345,096
• Publication Number:
  US 20100169087A1
• Time in Patent Office: 1,261 Days
• Field of Search: 704/500
• US Class Current: 704/500
• CPC Class Codes: G10L 19/24 Variable rate codecs, e.g. for generating different qualities using a scalable representation such as hierarchical encoding or layered encoding

Abstract

A set of peaks in a reconstructed audio vector Ŝ of a received audio signal is detected and a scaling mask ψ(Ŝ) based on the detected set of peaks is generated. A gain vector g* is generated based on at least the scaling mask and an index j representative of the gain vector. The reconstructed audio signal is scaled with the gain vector to produce a scaled reconstructed audio signal. A distortion is generated based on the audio signal and the scaled reconstructed audio signal. The index of the gain vector based on the generated distortion is output.

Claims

1. An apparatus that decodes an audio signal, comprising:

a gain vector decoder of an enhancement layer decoder that receives a reconstructed audio vector Ŝ and

an index representative of a gain vector,

wherein a gain selector of the gain vector decoder receives the index representative of the gain vector;

a gain selector of the gain vector decoder that detects a set of peaks in the reconstructed audio vector, generates a scaling mask ψ

(Ŝ

) based on the detected set of peaks, and generates the gain vector g* based on at least the scaling mask and the index representative of the gain vector;

a scaling unit of the gain vector decoder that scales the reconstructed audio vector with the gain vector to produce a scaled reconstructed audio signal.

2. The apparatus of claim 1, further comprising:

an error signal decoder that generates an enhancement to the reconstructed audio vector; and

a signal combiner of the enhancement layer decoder that combines the scaled reconstructed audio signal and the enhancement to the reconstructed audio vector to generate an enhanced decoded signal.

3. The apparatus of claim 1, wherein the gain selector detects the set of peaks in accordance with a peak detection function given as:

4. The apparatus of claim 1, wherein the audio signal is embedded in multiple layers.

5. The apparatus of claim 1, wherein the reconstructed audio vector Ŝ

is in the frequency domain and the set of peaks are frequency domain peaks.

6. The apparatus of claim 1, further comprising:

a decoder that receives a coded audio signal, a coded balance factor and a coded gain value;

wherein the gain vector decoder of an enhancement layer decoder that generates a decoded gain value from the coded gain value;

wherein the scaling unit of the enhancement layer decoder that scales the coded audio signal with the decoded gain value to generate a scaled audio signal; and

further comprising;

a signal combiner that applies the coded balance factor to the scaled audio signal to generate a decoded multiple channel audio signal and outputs the decoded multiple channel audio signal.

7. A method for decoding an audio signal, the method comprising:

receiving a reconstructed audio vector Ŝ and

an index representative of a gain vector;

detecting a set of peaks in the reconstructed audio vector;

generating a scaling mask ψ

(Ŝ

) based on the detected set of peaks;

generating the gain vector g* based on at least the scaling mask and the index representative of the gain vector; and

scaling the reconstructed audio vector with the gain vector to produce a scaled reconstructed audio signal.

8. The method of claim 7, further comprising:

generating an enhancement to the reconstructed audio vector; and

combining the scaled reconstructed audio signal and the enhancement to the reconstructed audio vector to generate an enhanced decoded signal.

9. The method of claim 7, wherein detecting the set of peaks further comprises a peak detection function given as:

10. The method of claim 7, further comprising:

receiving a coded audio signal, a coded balance factor and a coded gain value;

generating a decoded gain value from the coded gain value;

scaling the coded audio signal with the decoded gain value to generate a scaled audio signal;

applying a coded balance factor to the scaled audio signal to generate a decoded multiple channel audio signal; and

outputting the decoded multiple channel audio signal.

11. A method for encoding an audio signal, the method comprising:

receiving an audio signal;

encoding the audio signal to generate a reconstructed audio vector Ŝ

;

detecting a set of peaks in the reconstructed audio vector Ŝ

of a received audio signal;

generating a scaling mask ψ

(Ŝ

) based on the detected set of peaks;

generating a plurality of gain vectors g_j based on the scaling mask;

scaling the reconstructed audio signal with the plurality of gain vectors to produce the plurality of scaled reconstructed audio signals;

generating a plurality of distortions based on the audio signal and a plurality of scaled reconstructed audio signals;

choosing a gain vector from the plurality of gain vectors based on the plurality of distortions; and

outputting for at least one of transmitting and storing the index representative of the gain vector.

13. The method of claim 11, wherein detecting the set of peaks further comprises a peak detection function given as:

14. The method of claim 11, wherein the audio signal is embedded in multiple layers.

15. The method of claim 11, wherein the reconstructed audio vector ŝ

is in the frequency domain and the set of peaks are frequency domain peaks.

12. The method of 11, wherein the gain vector is chosen that corresponds with a minimum distortion of the plurality of distortions.