Method and system for reduction of quantization-induced block-discontinuities and general purpose audio codec

• US 20050159940A1
• Filed: 03/09/2005
• Published: 07/21/2005
• Est. Priority Date: 05/27/1999
• Status: Active Grant

• Current Assignee: Meta Platforms, Inc. (f/k/a Facebook, Inc.)
• Original Assignee: America Online Inc. (Warner Bros. Discovery, Inc.)
• Inventors: Perlmutter, Keren, Mantegna, John, Wu, Shuwu
• Granted Patent: US 7,181,403 B2
• Time in Patent Office: Days
• US Class Current: 704/203
• 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 19/0212 using orthogonal transformation
• CPC Class Codes: G10L 19/022 Blocking, i.e. grouping of samples in time; Choice of analysis windows; Overlap factoring
• 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 19/038 Vector quantisation, e.g. TwinVQ audio
• CPC Class Codes: G10L 2019/0012 Smoothing of parameters of the decoder interpolation

Abstract

Compressing the digitized time-domain continuous input signal typically includes formatting the input signal into a plurality of time-domain blocks having boundaries, forming an overlapping time-domain block by prepending a fraction of a previous time-domain block to a current time-domain block, transforming each overlapping time-domain block to a transform domain block including a plurality of coefficients, partitioning the coefficients of each transform domain block into signal coefficients and residue coefficients, quantizing the signal coefficients for each transformed domain block and generating signal quantization indices indicative of such quantization, modeling the residue coefficients for each transform domain block as stochastic noise and generating residue quantization indices indicative of such quantization, and formatting the signal quantization indices and the residue quantization indices for each transform domain block as an output bit-stream. The continuous data may include audio data.

Claims

1-15. -15. (canceled)

16. A method for performing an adaptive cosine packet transform, including:

calculating bell window functions;

calculating a cosine packet transform table for at least one time splitting level utilizing the bell window functions;

determining whether a pre-split at the time splitting level is needed for a current frame;

recalculating the cosine packet transform table at selected levels depending on the pre-split determination;

building a statistics tree for only the selected levels;

generating an extended statistics tree from the statistics tree;

performing a best basis analysis to determine an extended best basis tree from the extended statistics tree; and

determining optimal transform coefficients from the extended best basis tree.

17. The method claim 16 further including:

determining how to perform the pre-split for the current cosine packet transform frame to form the pre-split subframes; and

performing the pre-split for the current cosine packet transform frame to form the pre-split subframes.

18. A method for performing an adaptive cosine packet transform, including:

determining whether a pre-split is needed for a current cosine packet transform frame to form pre-split subframes;

applying a cosine packet transform to the pre-split subframes based on the determination;

performing a best basis analysis; and

determining optimal transform coefficients.

19. The method claim 18 further including:

determining how to perform the pre-split for the current cosine packet transform frame to form the pre-split subframes; and

performing the pre-split for the current cosine packet transform frame to form the pre-split subframes.

20. The method of claim 18 further including:

calculating bell window functions; and

calculating a cosine packet transform table only for a time splitting level utilizing the bell window functions.

21. The method of claim 18 wherein performing the best basis analysis includes:

building a statistics tree for the pre-split subframes;

generating an extended statistics tree from the statistics tree; and

performing the best basis analysis to determine an extended best basis tree from the extended statistics tree.

22. The method of claim 21 wherein determining the optimal transform coefficients includes determining the optimal transform coefficients from the extended best basis tree.

23-42. -42. (canceled)

43. A method for performing an inverse adaptive cosine packet transform, including:

calculating bell window functions;

joining an extended best basis tree into a combined best basis tree; and

synthesizing a time-domain signal from optimal cosine packet coefficients using the bell window functions.

44. The method of claim 43 further including applying the inverse adaptive cosine packet transform to signal coefficients to generate a time-domain reconstructed signal waveform.

45-60. -60. (canceled)

61. A computer program, residing on a computer-readable medium, for performing an adaptive cosine packet transform, the computer program comprising instructions for causing a computer to:

calculate bell window functions;

calculate a cosine packet transform table for at least one time splitting level utilizing the bell window functions;

determine whether a pre-split at the time splitting level is needed for a current frame;

recalculate the cosine packet transform table at selected levels depending on the pre-split determination;

build a statistics tree for only the selected levels;

generate an extended statistics tree from the statistics tree;

perform a best basis analysis to determine an extended best basis tree from the extended statistics tree; and

determine optimal transform coefficients from the extended best basis tree.

62. The computer program of claim 61 further including instructions for causing the computer to:

determine how to perform the pre-split for the current cosine packet transform frame to form the pre-split subframes; and

perform the pre-split for the current cosine packet transform frame to form the pre-split subframes.

63. A computer program, residing on a computer-readable medium, for performing an adaptive cosine packet transform, the computer program comprising instructions for causing a computer to:

determine whether a pre-split is needed for a current cosine packet transform frame to form pre-split subframes;

apply a cosine packet transform to the pre-split subframes based on the determination;

perform a best basis analysis; and

determine optimal transform coefficients.

64. The computer program of claim 63 further including instructions for causing the computer to:

determine how to perform the pre-split for the current cosine packet transform frame to form the pre-split subframes; and

perform the pre-split for the current cosine packet transform frame to form the pre-split subframes.

65. The computer program of claim 63 further including instructions for causing the computer to:

calculate bell window functions; and

calculate a cosine packet transform table only for a time splitting level utilizing the bell window functions.

66. The computer program of claim 63 wherein the instructions for causing the computer to perform the best basis analysis includes instructions for causing the computer to:

build a statistics tree for the pre-split subframes;

generate an extended statistics tree from the statistics tree; and

perform the best basis analysis to determine an extended best basis tree from the extended statistics tree.

67. The computer program of claim 66 wherein the instructions for causing the computer to determine the optimal transform coefficients includes instructions for causing the computer to determine the optimal transform coefficients from the extended best basis tree.

68-87. -87. (canceled)

88. A computer program, residing on a computer-readable medium, for performing an inverse adaptive cosine packet transform, the computer program comprising instructions for causing a computer to:

calculate bell window functions;

join an extended best basis tree into a combined best basis tree; and

synthesize a time-domain signal from optimal cosine packet coefficients using the bell window functions.

89. The computer program of claim 88 further including instructions for causing the computer to apply the inverse adaptive cosine packet transform to signal coefficients to generate a time-domain reconstructed signal waveform.

90-105. -105. (canceled)

106. A system for performing an adaptive cosine packet transform, including:

means for calculating bell window functions;

means for calculating a cosine packet transform table for at least one time splitting level utilizing the bell window functions;

means for determining whether a pre-split at the time splitting level is needed for a current frame;

means for recalculating the cosine packet transform table at selected levels depending on the pre-split determination;

means for building a statistics tree for only the selected levels;

means for generating an extended statistics tree from the statistics tree;

means for performing a best basis analysis to determine an extended best basis tree from the extended statistics tree; and

means for determining optimal transform coefficients from the extended best basis tree.

107. The system claim 106 further including:

means for determining how to perform the pre-split for the current cosine packet transform frame to form the pre-split subframes; and

means for performing the pre-split for the current cosine packet transform frame to form the pre-split subframes.

108. A system for performing an adaptive cosine packet transform, including:

means for determining whether a pre-split is needed for a current cosine packet transform frame to form pre-split subframes;

means for applying a cosine packet transform to the pre-split subframes based on the determination;

means for performing a best basis analysis; and

means for determining optimal transform coefficients.

109. The system of claim 108 further including:

means for determining how to perform the pre-split for the current cosine packet transform frame to form the pre-split subframes; and

means for performing the pre-split for the current cosine packet transform frame to form the pre-split subframes.

110. The system of claim 108 further including:

means for calculating bell window functions; and

means for calculating a cosine packet transform table only for a time splitting level utilizing the bell window functions.

111. The system of claim 108 wherein the means for performing the best basis analysis includes:

means for building a statistics tree for the pre-split subframes;

means for generating an extended statistics tree from the statistics tree; and

means for performing the best basis analysis to determine an extended best basis tree from the extended statistics tree.

112. The system of claim 111 wherein the means for determining the optimal transform coefficients includes means for determining the optimal transform coefficients from the extended best basis tree.

113-132. -132. (canceled)

133. A system for performing an inverse adaptive cosine packet transform, including:

means for calculating bell window functions;

means for joining an extended best basis tree into a combined best basis tree; and

means for synthesizing a time-domain signal from optimal cosine packet coefficients using the bell window functions.

134. The system of claim 133 further including means for applying the inverse adaptive cosine packet transform to signal coefficients to generate a time-domain reconstructed signal waveform.