Apparatus and method for encoding/decoding for high frequency bandwidth extension

• US 10,453,466 B2
• Filed: 12/10/2018
• Issued: 10/22/2019
• Est. Priority Date: 12/29/2010
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Choo, Ki-hyun, Oh, Eun-mi, Sung, Ho-sang
• Primary Examiner(s): Opsasnick, Michael N
• Application Number:
  US16/215,079
• Publication Number:
  US 20190115037A1
• Time in Patent Office: 316 Days
• Field of Search: 704500-504
• CPC Class Codes: G10L 19/00 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 Class Codes: G10L 19/038 Vector quantisation, e.g. TwinVQ audio
• 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 19/24 Variable rate codecs, e.g. for generating different qualities using a scalable representation such as hierarchical encoding or layered encoding
• CPC Class Codes: G10L 21/038 using band spreading techniques

Abstract

A method and apparatus for performing coding and decoding for high-frequency bandwidth extension. The coding apparatus may classify a coding mode of a low-frequency signal of an input signal based on characteristics of the low-frequency signal of an input signal, perform code excited linear prediction coding or audio coding on the LPC excitation signal of the low-frequency signal of an input signal, and perform time-domain (TD) extension coding or frequency-domain (FD) extension coding on a high-frequency signal of an input signal. When the FD extension coding is performed, the coding apparatus may generate a base excitation signal for a high band using an input spectrum, obtain an energy control factor of a sub-band in a frame using the base excitation signal and the input spectrum, generate an energy signal based on the input spectrum and the energy control factor, for the sub-band in the frame, and quantize the energy signal.

Claims

1. An apparatus for coding an input signal comprising:

at least one of processor configured to;

classify a coding mode of a low-frequency signal of the input signal based on characteristics of the low-frequency signal of the input signal;

when the coding mode is classified as a speech coding mode, perform code excited linear prediction (CELP) coding on a linear prediction coefficient (LPC) excitation signal of the low-frequency signal of the input signal;

when the CELP coding is performed on the LPC excitation signal, perform time-domain (TD) extension coding on a high-frequency signal of the input signal;

when the coding mode is classified as an audio coding mode, perform audio coding on the LPC excitation signal of the low-frequency signal of the input signal; and

when the audio coding is performed on the LPC excitation signal, perform frequency-domain (FD) extension coding on the high-frequency signal of the input signal;

wherein said at least one of processor is further configured to;

when the frequency-domain extension coding is performed, generate a base excitation signal for a high band using an input spectrum;

obtain an energy control factor of a sub-band in a frame, using the base excitation signal and the input spectrum;

generate an energy signal based on the input spectrum and the energy control factor, for the sub-band in the frame; and

quantize the generated energy signal.

2. The apparatus of claim 1, wherein the at least one of processor is further configured to, when the frequency-domain extension coding is performed, perform energy quantization by sharing a same codebook at different bitrates.

3. The apparatus of claim 1, wherein the at least one of processor is further configured to vector-quantize the energy signal by assigning a weight to a low-frequency band of high perceptual importance.

4. The apparatus of claim 1, wherein the at least one of processor is further configured to quantize the energy signal by assigning a larger number of bits to a low-frequency band of high perceptual importance than to a high-frequency band.

5. The apparatus of claim 1, wherein the at least one of processor is further configured to obtain the energy control factor based on a ratio between tonality of the base excitation signal and tonality of the input spectrum.

6. The apparatus of claim 1, wherein the at least one of processor is further configured to quantize the energy signal based on a weighted mean square error (WMSE).

7. The apparatus of claim 1, wherein the at least one of processor is further configured to quantize the energy signal based on an interpolation process.

8. The apparatus of claim 1, wherein the at least one of processor is further configured to quantize the energy signal by using a multi-stage vector quantization.

9. The apparatus of claim 1, wherein the at least one of processor is further configured to select a plurality of vectors from among energy vectors and quantize the selected vectors and an error obtained by interpolating the selected vectors.

10. A method for coding an input signal, wherein the method comprising:

classifying a coding mode of a low-frequency signal of the input signal based on characteristics of the low-frequency signal of the input signal;

when the coding mode is classified as a speech coding mode, performing code excited linear prediction (CELP) coding on a linear prediction coefficient (LPC) excitation signal of the low-frequency signal of the input signal;

when the CELP coding is performed on the LPC excitation signal, performing time-domain (TD) extension coding on a high-frequency signal of the input signal;

when the coding mode is classified as an audio coding mode, performing audio coding on the LPC excitation signal of the low-frequency signal of the input signal; and

when the audio coding is performed on the LPC excitation signal, performing frequency-domain (FD) extension coding on the high-frequency signal of the input signal;

wherein the performing of the FD extension coding comprises;

generating a base excitation signal for a high band using an input spectrum;

obtaining an energy control factor of a sub-band in a frame, using the base excitation signal and the input spectrum;

generating an energy signal based on the input spectrum and the energy control factor, for the sub-band in the frame; and

quantizing the generated energy signal.

11. The method of claim 10, wherein the performing of the FD extension coding comprises performing energy quantization by sharing a same codebook at different bitrates.

12. The method of claim 10, wherein the quantizing of the generated energy signal comprises vector-quantizing the energy signal by assigning a weight to a low-frequency band of high perceptual importance.

13. The method of claim 10, wherein the quantizing of the generated energy signal comprises quantizing the energy signal by assigning a larger number of bits to a low-frequency band of high perceptual importance than to a high-frequency band.

14. The method of claim 10, wherein the obtaining of the energy control factor comprises obtaining the energy control factor based on a ratio between tonality of the base excitation signal and tonality of the input spectrum.

15. The method of claim 10, wherein the quantizing of the generated energy signal comprises quantizing the energy signal based on a weighted mean square error (WMSE).

16. The method of claim 10, wherein the quantizing of the generated energy signal comprises quantizing the energy signal based on an interpolation process.

17. The method of claim 10, wherein the quantizing of the generated energy signal comprises quantizing the energy signal by using a multi-stage vector quantization.

18. The method of claim 10, wherein the quantizing of the generated energy signal comprises selecting a plurality of vectors from among energy vectors and quantizing the selected vectors and an error obtained by interpolating the selected vectors.