Apparatus and method for processing a time domain audio signal with a noise filling flag

• US 8,364,471 B2
• Filed: 11/04/2009
• Issued: 01/29/2013
• Est. Priority Date: 11/04/2008
• Status: Active Grant

• Current Assignee: LG Electronics, Inc. (LG Corporation)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: Yoon, Sung Yong, Lee, Hyun Kook, Kim, Dong Soo, Lim, Jae Hyun
• Primary Examiner(s): Lerner, Martin
• Application Number:
  US12/612,345
• Publication Number:
  US 20100114585A1
• Time in Patent Office: 1,182 Days
• Field of Search: 704/205, 704/206, 704/211, 704/226, 704/227, 704/500, 704/501, 704/229, 704/228, 704/230, 341/67
• US Class Current: 704/206
• CPC Class Codes: G10L 19/028 Noise substitution, i.e. substituting non-tonal spectral components by noisy source comfort noise for discontinuous speech transmission G10L19/012
• CPC Class Codes: G10L 19/035 Scalar quantisation
• CPC Class Codes: G10L 19/167 Audio streaming, i.e. formatting and decoding of an encoded audio signal representation into a data stream for transmission or storage purposes
• CPC Class Codes: G10L 21/038 using band spreading techniques

Abstract

An apparatus and method for processing an audio signal including extracting noise filling flag information indicating whether noise filling is used to a plurality of frames; extracting coding scheme information indicating whether a current frame included in the plurality of frames is coded in either a frequency domain or a time domain; when the noise filling flag information indicates that the noise filling is used for the plurality of frames and the coding scheme information indicates that the current frame is coded in the frequency domain, extracting noise level information for the current frame; when a noise level value corresponding to the noise level information meets a predetermined level, extracting noise offset information for the current frame; and, when the noise offset information is extracted, performs the noise-filling for the current frame based on the noise level value and the noise offset information.

Claims

1. A method for processing an audio signal, the method comprising:

extracting, by an audio processing apparatus, spectral data and noise filling flag information indicating whether noise filling is used for a plurality of frames, the spectral data being inverse-quantized;

extracting coding scheme information indicating whether a current frame included in the plurality of frames is coded in either a frequency domain or a time domain;

when the noise filling flag information indicates that the noise filling is used for the plurality of frames and the coding scheme information indicates that the current frame is coded in the frequency domain, extracting noise level information for the current frame, and noise offset information for modifying a scale factor for the current frame, wherein the noise offset information is provided for a spectral band having a loss area corresponding to spectral data of zero; and

performing the noise-filling for the current frame based on a noise level value and the noise offset information, the noise level value corresponding to the noise level information which comprises;

determining the loss area of the current frame based on the spectral data of the current frame;

generating a compensated spectral data of the current frame by filling the loss area with a random signal using the noise level value corresponding to the noise level information; and

generating a compensated scale factor by modifying the scale factor of the current frame based on the noise offset information,

wherein the compensated scale factor is applied to the spectral band corresponding to at least one spectral data.

2. The method of claim 1, further comprising:

extracting a level pilot value representing a reference value of a noise level, and an offset pilot value representing a reference value of a noise offset;

obtaining the noise level value by summing the level pilot value and the noise level information; and

when the noise offset information is extracted, obtaining a noise offset value by summing the offset pilot value and the noise offset information,

wherein the noise filling is performed using the noise level value and the noise offset value.

3. The method of claim 1, further comprising:

obtaining the noise level value of the current frame using a noise level value of a previous frame and the noise level information of the current frame; and

when the noise offset information is extracted, obtaining a noise offset value of the current frame using a noise offset value of the previous frame and the noise offset information of the current frame,

wherein the noise filling is performed using the noise level value and the noise offset value.

4. The method of claim 1, wherein both the noise level information and the noise offset information are extracted according to variable length coding scheme.

5. The method of claim 1, wherein the noise offset information is extracted when the noise level value meets a predetermined level.

6. An apparatus for processing an audio signal, the apparatus comprising:

a demultiplexer extracting, spectral data and noise filling flag information indicating whether noise filling is used for a plurality of frames, and coding scheme information indicating whether a current frame included in the plurality of frames is coded in either a frequency domain or a time domain, the spectral data being inverse-quantized;

a noise information decoding part using a processor, when the noise filling flag information indicates that the noise filling is used for the plurality of frames and the coding scheme information indicates that the current frame is coded in the frequency domain, extracting noise level information for the current frame, and noise offset information for modifying a scale factor for the current frame, wherein the noise offset information is provided for a spectral band having a loss area corresponding to spectral data of zero; and

a loss compensation part determining the loss area of the current frame based on the spectral data of the current frame, generating a compensated spectral data of the current frame by filling the loss area with a random signal using a noise level value corresponding to the noise level information, and generating a compensated scale factor by modifying the scale factor of the current frame based on the noise offset information,

wherein the scale factor is applied to the spectral band corresponding to at least one spectral data.

7. The apparatus of claim 6, further comprising:

a data decoding part configured to;

extract a level pilot value representing a reference value of a noise level, and an offset pilot value representing a reference value of a noise offset,

obtain the noise level value by summing the level pilot value and the noise level information, and

when the noise offset information is extracted, obtain a noise offset value by summing the offset pilot value and the noise offset information,

wherein the noise filling is performed using the noise level value and the noise offset value.

8. The apparatus of claim 6, further comprising:

a data decoding part configured to;

obtain the noise level value of the current frame using a noise level value of a previous frame and the noise level information of the current frame, and

when the noise offset information is extracted, obtain a noise offset value of the current frame using a noise offset value of the previous frame and the noise offset information of the current frame,

wherein the noise filling is performed using the noise level value and the noise offset value.

9. The apparatus of claim 6, wherein both the noise level information and the noise offset information are extracted according to variable length coding scheme.

10. A method for processing an audio signal, the method comprising:

receiving, by an audio processing apparatus, a spectral data and a scale factor as a quantized signal, wherein the scale factor is applied to a spectral band corresponding to at least one spectral data;

generating a noise level value and a noise offset value based on the quantized signal;

generating noise filling flag information indicating whether noise filling is used to a plurality of frames;

generating coding scheme information indicating whether a current frame included in the plurality of frames is coded in either a frequency domain or a time domain;

when the noise filling flag information indicates that the noise filling is used to for the plurality of frames and the coding scheme information indicates that the current frame is coded in the frequency domain, inserting noise level information for the current frame corresponding to the noise level value and noise offset information corresponding to the noise offset value into a bitstream,

wherein the noise offset information is used for modifying the scale factor for the current frame, and the noise offset information is provided for a spectral band having a loss area corresponding to spectral data of zero.

11. The method of claim 10, wherein the noise offset information is inserted into the bitstream when the noise level value meets a predetermined level.

12. An apparatus for processing an audio signal, the apparatus comprising:

a loss compensation estimating part using a processor receiving a spectral data and a scale factor as a quantized signal, wherein the scale factor is applied to a spectral band corresponding to at least one spectral data, and generating a noise level value and a noise offset value based on the quantized signal, and noise filling flag information indicating whether noise filling is used for a plurality of frames;

a signal classifier generating coding scheme information indicating whether a current frame included in the plurality of frames is coded in either a frequency domain or a time domain; and

a noise information encoding part, when the noise filling flag information indicates that the noise filling is used for the plurality of frames and the coding scheme information indicates that the current domain is coded in the frequency domain, inserting noise level information for the current frame corresponding to the noise level value and noise offset information corresponding to the noise offset value into a bitstream,

wherein the noise offset information is used for modifying the scale factor for the current frame, and

wherein the noise offset information is provided for a spectral band having a loss area corresponding to spectral data of zero.

13. A non-transitory computer-readable medium having instructions stored thereon, which, when executed by a processor, causes the processor to perform operations, comprising:

extracting, by an audio processing apparatus, spectral data and noise filling flag information indicating whether noise filling is used for a plurality of frames, the spectral data being inverse-quantized;

extracting coding scheme information indicating whether a current frame included in the plurality of frames is coded in either a frequency domain or a time domain;

when the noise filling flag information indicates that the noise filling is used for the plurality of frames and the coding scheme information indicates that the current frame is coded in the frequency domain, extracting noise level information for the current frame and noise offset information for modifying a scale factor for the current frame, wherein the noise offset information is provided for a spectral band having a loss area corresponding to spectral data of zero; and

performing the noise-filling for the current frame based on a noise level value and the noise offset information, the noise level value corresponding to the noise level information which comprises;

determining the loss area of the current frame based on the spectral data of the current frame;

generating a compensated spectral data of the current frame by filling the loss area with a random signal using the noise level value corresponding to the noise level information; and

generating a compensated scale factor by modifying the scale factor of the current frame based on the noise offset information,

wherein the scale factor is applied to the spectral band corresponding to at least one spectral data.