Apparatus For Encoding and Decoding Audio Signal and Method Thereof

• US 20080212803A1
• Filed: 06/30/2006
• Published: 09/04/2008
• Est. Priority Date: 06/30/2005
• Status: Active Grant

• Current Assignee: LG Electronics, Inc. (LG Corporation)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: Pang, Hee Suk, Lim, Jae Hyun, Jung, Yang Won, Kim, Dong Soo, Oh, Hyen O, Yoon, Sung Young
• Granted Patent: US 8,494,667 B2
• Time in Patent Office: Days
• US Class Current: 381/119
• CPC Class Codes: G10L 19/008 Multichannel audio signal coding or decoding using interchannel correlation to reduce redundancy, e.g. joint-stereo, intensity-coding or matrixing

Abstract

A method and/or apparatus for encoding and/or decoding an audio signal is disclosed, in which a downmix gain is applied to a downmix signal in an encoding apparatus which, in turn, transmits, to a decoding apparatus, a bit stream containing information as to the applied downmix gain. The decoding apparatus recovers the downmix signal, using the downmix gain information. A method and/or apparatus for encoding and/or decoding an audio signal is also disclosed, in which the encoding apparatus can apply an arbitrary downmix gain (ADG) to the downmix signal, and can transmit a bit stream containing information as to the applied ADG to the decoding apparatus. The decoding apparatus recovers the downmix signal, using the ADG information. A method and/or apparatus for encoding and/or decoding an audio signal is also disclosed, in which the method and/or apparatus can also vary the energy level of a specific channel, and can recover the varied energy level.

Claims

1-19. -19. (canceled)

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

receiving the audio signal;

extracting a downmix signal from the audio signal;

extracting downmix gain information from the audio signal; and

selectively applying a downmix gain to the downmix signal based on the extracted downmix gain information.

21. The method according to claim 20, wherein the downmix gain is applied to the downmix signal in a time domain.

22. The method according to claim 20, wherein the downmix gain is applied to the downmix signal in a frequency domain.

23. The method according to claim 20, wherein the downmix gain is applied to an entire portion of the downmix signal.

24. The method according to claim 20, wherein the downmix gain is variably applied to the downmix signal per a plurality of frames or per frame.

25. The method according to claim 24, wherein the downmix gain is variable within a range smaller than one increment of the downmix gain, or is variable by one increment or decrement of the downmix gain per a plurality of frames.

26. The method according to claim 23, wherein the downmix gain information is extracted from a header of a spatial information signal included in the audio signal.

27. The method according to claim 26, wherein the header is contained in the spatial information signal for each frame of the bitstream, or is contained in the spatial information signal per a plurality of frames.

28. The method according to claim 27, wherein the header is periodically or non-periodically contained in the spatial information signal per a plurality of frames.

29. The method according to claim 24, wherein the downmix gain information is extracted from a frame containing downmix signal bits.

30. The method according to claim 20, further comprising:

decoding the downmix gain information in accordance with one of a plurality of predetermined values.

31. The method according to claim 20, wherein the downmix gain information is at least one bit indicating whether or not to apply the downmix gain.

32. The method according to claim 20, wherein the downmix gain information includes at least two bits indicating a level of a downmix gain to apply.

33. The method according to claim 32, wherein the level is one of 1, 2, 3, 4, √

{square root over (2)}, 2, √

{square root over (2)}, 4/3, and 3/2.

34. The method according to claim 20, wherein the downmix gain information is embedded within one of

a header of the audio signal,

a frame of the extracted downmix signal, and

spatial information of the audio signal.

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

generating a downmix signal and a spatial information signal from a multi-channel audio signal;

applying a downmix gain to the downmix signal; and

multiplexing the downmix signal and the spatial information signal to create the audio signal, the audio signal having downmix gain information embedded therein.

36. The method according to claim 35, wherein the downmix gain information is embedded within one of

a header of the audio signal,

a frame of the downmix signal, and

the spatial information signal.

37. The method according to claim 35, further comprising:

measuring at least one of a frequency of a sound level variation and a degree of the sound level variation occurring during a generation of the downmix signal; and

determining the downmix gain, using the at least one of the frequency and the degree.

38. The method according to claim 35, wherein, when the downmix signal corresponds to

$\sum _{}^{}$

k = 1 N 

a k ·

x k 

( n ) ,

the downmix gain has a maximum value determined as follows;

$\underset{k=1}{\overset{N}{\sum <br><br>}}<br><br>a_k$

(where, x_k(n) represents each channel signal of the multi-channel audio signal, a_k is a constant, and N is the number of channels).

39. The method according to claim 38, wherein the downmix gain is quantized to have a value ranging between the maximum value and 1.

40. An apparatus for decoding an audio signal, comprising:

a demultiplexer configured to separate a downmix signal and a spatial information signal from a bitstream of the audio signal;

a downmix gain applying unit to apply a downmix gain to the downmix signal based on extracted downmix gain information; and

a multi-channel generating unit configured to transform the downmix gain-applied downmix signal to a multi-channel audio signal, using the spatial information signal.

41. The apparatus according to claim 40, further comprising:

a downmix gain extracting unit configured to extract the downmix gain information from the spatial information signal.

42. The apparatus according to claim 40, wherein the downmix gain information is embedded within one of

a header of the audio signal,

a frame of the extracted downmix signal, and

the spatial information signal.

43. An apparatus for encoding an audio signal, comprising:

a downmixing unit configured to generate a downmix signal from a multi-channel audio signal;

a spatial information generating unit configured to extract a spatial information signal from the multi-channel audio signal; and

a downmix gain applying unit configured to apply a downmix gain to the downmix signal and to embed downmix gain information into one of the downmix signal and the spatial information signal.