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

• US 10,152,983 B2
• Filed: 12/28/2011
• Issued: 12/11/2018
• Est. Priority Date: 09/15/2010
• 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:
  US13/977,906
• Publication Number:
  US 20130282368A1
• Time in Patent Office: 2,540 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 down-sample an input signal, perform core coding on the down-sampled input signal, perform frequency transformation on the input signal, and perform bandwidth extension coding by using a base signal of the input signal in a frequency domain.

Claims

1. A coding method comprising:

receiving an input signal which is a time domain signal;

determining a core coding mode of a low-frequency signal of the input signal, based on characteristics of the low-frequency signal of the input signal;

extracting a linear prediction coefficient (LPC) from the low-frequency signal of the input signal, and quantizing the LPC;

performing, by using at least one processor, code excited linear prediction (CELP) coding on an LPC excitation signal of the low-frequency signal of the input signal, when the core coding mode of the low-frequency signal of the input signal is determined to be a CELP coding mode;

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

performing audio coding on the LPC excitation signal, when the core coding mode of the low-frequency signal of the input signal is determined to be an audio coding mode;

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

generating a bitstream based on either (1) a result of the CELP coding and a result of TD extension coding, or (2) a result of the audio coding and a result of the FD extension coding; and

transmitting the bitstream to a decoding side for reproduction,

wherein the performing of the FD extension coding comprises;

generating a base excitation signal for a high band using the input signal;

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

obtaining an energy signal of the sub-band in the frame from the input signal;

controlling, by using the at least one processor, the energy signal based on the energy control factor, for the sub-band in the frame; and

quantizing the controlled energy signal, and

wherein the controlling of the energy signal is performed when the frame is a harmonic frame or a normal frame other than a transient frame.

2. The coding method of claim 1, wherein the performing of the FD extension coding comprises performing energy quantization by sharing a same codebook at different bitrates.

3. The coding method of claim 1, wherein the bitstream according to the result of the audio coding includes previous frame mode information.

4. A non-transitory computer readable recording medium having recorded thereon a computer program for executing the method of claim 1.

5. The coding method of claim 1, wherein in the obtaining of the energy signal, the energy signal is extracted corresponding to each of frequency bands.

6. The coding method of claim 1, wherein in the quantizing of the controlled energy signal, the energy signal is vector-quantized by assigning a weight to a low-frequency band of high perceptual importance.

7. The coding method of claim 1, wherein in the quantizing of the controlled energy signal, the energy signal is quantized by assigning a larger number of bits to a low-frequency band of high perceptual importance than to a high-frequency band.

8. The coding method of claim 1, wherein the obtaining the energy control factor is based on a ratio between tonality of the base excitation signal and tonality of the input signal.

9. The coding method of claim 1, wherein the quantizing the controlled energy signal comprises quantizing the controlled energy signal based on a weighted mean square error (WMSE).

10. The coding method of claim 1, wherein the quantizing the controlled energy signal comprises quantizing the controlled energy signal based on an interpolation process.

11. The coding method of claim 1, wherein the quantizing the controlled energy signal comprises quantizing the controlled energy signal by using a multi-stage vector quantization.

12. The coding method of claim 1, wherein the quantizing the controlled energy signal comprises selecting a plurality of vectors from among energy vectors and quantize the selected vectors and an error obtained by interpolating the selected vectors.