QUANTIZATION AND INVERSE QUANTIZATION FOR AUDIO

• US 20080021704A1
• Filed: 09/25/2007
• Published: 01/24/2008
• Est. Priority Date: 09/04/2002
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Thumpudi, Naveen, Chen, Wei-Ge
• Granted Patent: US 7,801,735 B2
• Time in Patent Office: Days
• US Class Current: 704/230
• 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
• CPC Class Codes: G10L 19/032 Quantisation or dequantisation of spectral components

Abstract

An audio encoder and decoder use architectures and techniques that improve the efficiency of quantization (e.g., weighting) and inverse quantization (e.g., inverse weighting) in audio coding and decoding. The described strategies include various techniques and tools, which can be used in combination or independently. For example, an audio encoder quantizes audio data in multiple channels, applying multiple channel-specific quantizer step modifiers, which give the encoder more control over balancing reconstruction quality between channels. The encoder also applies multiple quantization matrices and varies the resolution of the quantization matrices, which allows the encoder to use more resolution if overall quality is good and use less resolution if overall quality is poor. Finally, the encoder compresses one or more quantization matrices using temporal prediction to reduce the bitrate associated with the quantization matrices. An audio decoder performs corresponding inverse processing and decoding.

Claims

1-32. -32. (canceled)

33. In an audio decoder, a computer-implemented method comprising:

receiving encoded audio data;

decoding the audio data, including applying plural quantization matrices in inverse quantization, wherein the resolution of the plural quantization matrices varies during the decoding.

37. The method of claim 33 wherein the resolution varies due to changing of quantization of information for the plural quantization matrices.

38. The method of claim 33 wherein the resolution varies due to changing of quantization of elements of the plural quantization matrices.

39. The method of claim 33 wherein the resolution is set on a channel-by-channel basis.

34-36. -36. (canceled)

40. (canceled)

41. (canceled)

42. In an audio encoder, a computer-implemented method comprising:

receiving audio data;

computing plural quantization matrices; and

compressing at least one of the plural quantization matrices using temporal prediction.

45. The method of claim 42 wherein the audio data is in more than two channels.

46. The method of claim 42 further comprising:

decompressing the plural quantization matrices; and

quantizing the audio data, including applying the plural quantization matrices.

47. The method of claim 42 further comprising outputting information for the plural compressed quantization matrices.

48. The method of claim 42 wherein the temporal prediction is from an anchor matrix to a current matrix within a channel.

50. The method of claim 42 wherein the compressing further includes performing a resampling process on an anchor matrix for temporal prediction of a current matrix with a different size than the anchor matrix.

51. The method of claim 42 wherein the compressing includes:

computing a prediction for a current matrix relative to another matrix; and

computing a residual from the current matrix and the prediction.

43. (canceled)

44. (canceled)

49. (canceled)

52. (canceled)

53. (canceled)

54. In an audio decoder, a computer-implemented method comprising:

receiving encoded audio data;

retrieving information for plural quantization matrices; and

decompressing at least one of the plural quantization matrices using temporal prediction.

57. The method of claim 54 wherein the audio data is in one or more channels.

58. The method of claim 54 further comprising inverse quantizing the audio data, including applying the plural quantization matrices, wherein the decoder performs the inverse quantizing in a combined step for quantization, and wherein for each of plural coefficients the combined step includes a single multiplication by a total quantization amount.

60. The method of claim 54 wherein the temporal prediction is from an anchor matrix to a current matrix within a channel.

61. The method of claim 60 wherein the decoder resets anchor matrices at the beginning of each frame.

63. The method of claim 54 wherein the decompressing further includes performing a resampling process on an anchor matrix for temporal prediction of a current matrix with a different size than the anchor matrix.

64. The method of claim 63 wherein the size is in terms of number of bands.

65. The method of claim 54 wherein the decompressing includes:

computing a prediction for a current matrix relative to another matrix;

decoding a residual for the current matrix; and

adding the residual and the prediction for the current matrix.

67. The method of claim 54 wherein the decompressing includes:

computing a prediction for a current matrix relative to another matrix;

getting a bit that indicates the presence or absence of a residual for the current matrix; and

if the residual is present for the current matrix, decoding the residual and adding the residual and the prediction for the current matrix.

55. (canceled)

56. (canceled)

59. (canceled)

62. (canceled)

66. (canceled)

68. (canceled)