# US 11,114,110 B2 · Noise attenuation at a decoder > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,114,110 B2 - Document ID: US11114110B2 - Status: Granted - Kind: B2 - Application number: 16/856,537 - Filed: 2020-04-23 - Published: 2020-08-06 - Granted: 2021-09-07 - Earliest claimed: 2017-10-27 - Assignees: Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. - Applicants: Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. - Inventors: Guillaume Fuchs; Tom Bäckström; Sneha Das - Web page: https://patentgrep.com/patent/US11114110B2 ## CPC - G10L 19/26: Pre-filtering or post-filtering - G10L 21/0232: Processing in the frequency domain - G10L 19/032: Quantisation or dequantisation of spectral components - G10L 21/0264: characterised by the type of parameter measurement, e.g. correlation techniques, zero crossing techniques or predictive techniques - G10L 19/24: Variable rate codecs, e.g. for generating different qualities using a scalable representation such as hierarchical encoding or layered encoding - G10L: SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING ## Abstract There are provided examples of decoders and decoding methods. One decoder includes: a bitstream reader to provide a version of an input signal as a sequence of frames, each frame subdivided into a plurality of bins, each bin having a sampled value; a context definer to define a context for one bin under process, the context including at least one additional bin in a predetermined positional relationship with the bin under process; a statistical relationship and information estimator to provide statistical relationships between the bin under process and the at least one additional bin; and a value estimator to process and acquire an estimate of the value of the bin. There is included a noise relationship and information estimator providing statistical relationships and information regarding noise, which includes a noise matrix estimating relationships among noise signals among the bin under process and the at least one additional bin. ## Claims ### Claim 1 A decoder for decoding a frequency-domain input signal defined in a bitstream, the frequency-domain input signal being subjected to noise, the decoder comprising: a bitstream reader to provide, from the bitstream, a version of the frequency-domain input signal as a sequence of frames, each frame being subdivided into a plurality of bins, each bin comprising a sampled value; a context definer configured to define a context for one bin under process, the context comprising at least one additional bin in a predetermined positional relationship with the bin under process; a statistical relationship and information estimator configured to provide: statistical relationships between the bin under process and the at least one additional bin, the statistical relationships being provided in form of covariances or correlations; and information regarding the bin under process and the at least one additional bin, the information being provided in form of variances or autocorrelations, wherein the statistical relationship and information estimator comprises a noise relationship and information estimator configured to provide statistical relationships and information regarding noise, wherein the statistical relationships and information regarding noise comprise a noise matrix (ΛN) estimating relationships among noise signals among the bin under process and the at least one additional bin; a value estimator configured to process and acquire an estimate of the value of the bin under process on the basis of the estimated statistical relationships between the bin under process and the at least one additional bin and the information regarding the bin under process and the at least one additional bin, and the statistical relationships and information regarding noise, and a transformer to transform the estimate into a time-domain signal. ### Claim 2 (depends on 1) The decoder of claim 1, wherein noise is quantization noise. ### Claim 3 (depends on 1) The decoder according to claim 1, wherein noise is noise which is not quantization noise. ### Claim 4 (depends on 1) The decoder of claim 1, wherein the context definer is configured to choose the at least one additional bin among previously processed bins. ### Claim 5 (depends on 1) The decoder of claim 1, wherein the context definer is configured to choose the at least one additional bin based on the band of the bin. ### Claim 6 (depends on 1) The decoder of claim 1, wherein the context definer is configured to choose the at least one additional bin, within a predetermined position threshold, among those which have already been processed. ### Claim 7 (depends on 1) The decoder of claim 1, wherein the context definer is configured to choose different contexts for bins at different bands. ### Claim 8 (depends on 1) The decoder of claim 1, wherein the value estimator is configured to operate as a Wiener filter to provide an optimal estimation of the frequency-domain input signal. ### Claim 9 (depends on 1) The decoder of claim 1, wherein the value estimator is configured to acquire the estimate of the value of the bin under process from at least one sampled value of the at least one additional bin. ### Claim 10 (depends on 1) The decoder of claim 1, further comprising a measurer configured to provide a measured value associated to the previously performed estimate(s) of the least one additional bin of the context, wherein the value estimator is configured to acquire an estimate of the value of the bin under process on the basis of the measured value. ### Claim 11 (depends on 10) The decoder of claim 10, wherein the measured value is a value associated to the energy of the at least one additional bin of the context. ### Claim 12 (depends on 10) The decoder of claim 10, wherein the measured value is a gain (γ) associated to the at least one additional bin of the context. ### Claim 13 (depends on 12) The decoder of claim 12, wherein the measurer is configured to acquire the gain as the scalar product of vectors, wherein a first vector comprises value(s) of the at least one additional bin of the context, and the second vector is the transpose conjugate of the first vector. ### Claim 14 (depends on 1) The decoder of claim 1, wherein the statistical relationship and information estimator is configured to provide the statistical relationships and information as pre-defined estimates or expected statistical relationships between the bin under process and the at least one additional bin of the context. ### Claim 15 (depends on 1) The decoder of claim 1, wherein the statistical relationship and information estimator is configured to provide the statistical relationships and information as relationships based on positional relationships between the bin under process and the at least one additional bin of the context. ### Claim 16 (depends on 1) The decoder of claim 1, wherein the statistical relationship and information estimator is configured to provide the statistical relationships and information irrespective of the values of the bin under process or the at least one additional bin of the context. ### Claim 17 (depends on 1) The decoder of claim 1, wherein the statistical relationship and information estimator is configured to provide the statistical relationships and information in the form of a matrix establishing relationships of variance and covariance values, or correlation and autocorrelation values, between the bin under process and the at least one additional bin of the context. ### Claim 18 (depends on 1) The decoder of claim 1, wherein the statistical relationship and information estimator is configured to provide the statistical relationships and information in the form of a normalized matrix establishing relationships of variance and covariance values, or correlation and autocorrelation values, between the bin under process and the at least one additional bin of the context. ### Claim 19 (depends on 17) The decoder of claim 17, wherein the value estimator is configured to scale elements of the matrix by an energy-related or gain value, so as to keep into account the energy and gain variations of the bin under process and the at least one additional bin of the context. ### Claim 20 (depends on 1) The decoder of claim 1, wherein the value estimator is configured to acquire the estimate of the value of the bin under process on the basis of a relationship {circumflex over (x)}=ΛX(ΛX+ΛN)−1y, where ΛX, ΛN∈(C+1)×(C+1) are noise and covariance matrices, respectively, and y∈c+1 is a noisy observation vector with c+1 dimensions, c being the context length. ### Claim 21 (depends on 1) The decoder of claim 1, wherein the statistical relationships between and information regarding the bin under process and the at least one additional bin comprises a normalized covariance matrix ΛX∈(C+1)×(C+1), wherein the statistical relationships and information regarding the noise comprises a noise matrix ΛN∈(C+1)×(C+1), wherein a noisy observation vector y∈c+1 is defined with c+1 dimensions, c being the context length, wherein the noisy observation vector is y=[yC0 yC1 yC2 yC3 . . . yC10] and comprises a noisy input yC0 associated to the bin under process and yC1 yC2 yC3, . . . yC10 being the at least one additional bin, wherein the value estimator is configured to acquire the estimate of the value of the bin under process on the basis of the relationship {circumflex over (x)}=γΛX(γΛX+ΛN)−1y, γ being the gain. ### Claim 22 (depends on 1) The decoder of claim 1, wherein the value estimator is configured to acquire the estimate of the value of the bin under process provided that the sampled values of each of the additional bins of the context correspond to the estimated value of the additional bins of the context. ### Claim 23 (depends on 1) The decoder of claim 1, wherein the value estimator is configured to acquire the estimate of the value of the bin under process provided that the sampled value of the bin under process is expected to be between a ceiling value and a floor value. ### Claim 24 (depends on 1) The decoder of claim 1, wherein the value estimator is configured to acquire the estimate of the value of the bin under process on the basis of a maximum of a likelihood function. ### Claim 25 (depends on 1) The decoder of claim 1, wherein the value estimator is configured to acquire the estimate of the value of the bin under process on the basis of an expected value. ### Claim 26 (depends on 1) The decoder of claim 1, wherein the value estimator is configured to acquire the estimate of the value of the bin under process on the basis of the expectation of a multivariate Gaussian random variable. ### Claim 27 (depends on 1) The decoder of claim 1, wherein the value estimator is configured to acquire the estimate of the value of the bin under process on the basis of the expectation of a conditional multivariate Gaussian random variable. ### Claim 28 (depends on 1) The decoder of claim 1, wherein the sampled values are in the Log-magnitude domain. ### Claim 29 (depends on 1) The decoder of claim 1, wherein the sampled values are in the perceptual domain. ### Claim 30 A decoder for decoding a frequency-domain input signal defined in a bitstream, the frequency-domain input signal being subjected to noise, the decoder comprising: a bitstream reader to provide, from the bitstream, a version of the frequency-domain input signal as a sequence of frames, each frame being subdivided into a plurality of bins, each bin comprising a sampled value; a context definer configured to define a context for one bin under process, the context comprising at least one additional bin in a predetermined positional relationship with the bin under process; a statistical relationship and information estimator configured to provide statistical relationships between the bin under process and the at least one additional bin and information regarding the bin under process and the at least one additional bin, wherein the relationships and information comprise a variance-related and/or standard-deviation-value-related value on the basis of variance-related and covariance-related relationships between the bin under process and the at least one additional bin of the context to a value estimator, wherein the statistical relationship and information estimator comprises a noise relationship and information estimator configured to provide statistical relationships and information regarding noise, wherein the statistical relationships and information regarding noise comprise, for each bin, a ceiling value and a floor value for estimating the signal on the basis of the expectation of the signal to be between the ceiling value and the floor value; the value estimator being configured to process and acquire an estimate of the value of the bin under process on the basis of the estimated statistical relationships between the bin under process and the at least one additional bin and the information regarding the bin under process and the at least one additional bin, and the statistical relationships and information regarding noise; and the decoder further comprising a transformer to transform the estimate into a time-domain signal. ### Claim 31 (depends on 30) The decoder of claim 30, wherein the statistical relationship and information estimator is configured to provide an average value of the signal to the value estimator. ### Claim 32 (depends on 30) The decoder of claim 30, wherein the statistical relationship and information estimator is configured to provide an average value of the clean signal on the basis of the variance-related and covariance-related relationships between the bin under process and at least one additional bin of the context. ### Claim 33 (depends on 30) The decoder of claim 30, wherein the statistical relationship and information estimator is configured to provide an average value of the clean signal on the basis of the expected value of the bin under process. ### Claim 34 (depends on 33) The decoder of claim 33, wherein the statistical relationship and information estimator is configured to update an average value of the signal based on the estimated context. ### Claim 35 (depends on 30) The decoder of claim 30, wherein the version of the frequency-domain input signal comprises a quantized value which is a quantization level, the quantization level being a value chosen from a discrete number of quantization levels. ### Claim 36 (depends on 35) The decoder of claim 35, wherein the number or values or scales of the quantization levels are signaled in the bitstream. ### Claim 37 (depends on 1) The decoder of claim 1, wherein the value estimator is configured to acquire the estimate of the value of the bin under process in terms of x ^ = E ⁡ [ P ⁡ ( X | X c = x ^ c ) ] ⁢ ⁢ subjectto l ≤ X ≤ u . where {circumflex over (x)} is the estimate of the bin under process, l and u are the lower and upper limits of the current quantization bins, respectively, and P(a1|a2) is the conditional probability of a1, given a2, {circumflex over (x)}c being an estimated context vector. ### Claim 38 (depends on 30) The decoder of claim 30, wherein the value estimator is configured to acquire the estimate of the value of the bin under process in terms of x ^ = E ⁡ [ P ⁡ ( X | X c = x ^ c ) ] ⁢ ⁢ subjectto l ≤ X ≤ u . where {circumflex over (x)} is the estimate of the bin under process, l and u are the lower and upper limits of the current quantization bins, respectively, and P(a1|a2) is the conditional probability of a1, given a2, {circumflex over (x)}c being an estimated context vector. ### Claim 39 (depends on 1) The decoder of claim 1, wherein the value estimator is configured to acquire the estimate of the value of the bin under process on the basis of the expectation E ⁡ ( X | l < X < u ) = μ - σ ⁢ 2 π ⁡ [ f 1 ⁡ ( u ) - f 1 ⁡ ( l ) f 2 ⁡ ( u ) - f 2 ⁡ ( l ) ] wherein X is a particular value of the bin under process expressed as a truncated Gaussian random variable, with l