# US 11,451,919 B2 · All-pass network system for colorless decorrelation with constraints > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,451,919 B2 - Document ID: US11451919B2 - Status: Granted - Kind: B2 - Application number: 17/180,643 - Filed: 2021-02-19 - Published: 2022-08-25 - Granted: 2022-09-20 - Earliest claimed: 2021-02-19 - Assignees: Boomcloud 360, Inc. - Applicants: Boomcloud 360, Inc. - Inventors: Joseph Anthony Mariglio, III - Web page: https://patentgrep.com/patent/US11451919B2 ## CPC - H04S 5/00: Pseudo-stereo systems, e.g. in which additional channel signals are derived from monophonic signals by means of phase shifting, time delay or reverberation - H04S 5/02: of the pseudo four-channel type, e.g. in which rear channel signals are derived from two-channel stereo signals - H04S: STEREOPHONIC SYSTEMS ## Abstract A system includes one or more computing devices that decorrelates a monaural channel into a plurality of output channels. A computing device determines a target amplitude response defining one or more constraints on a summation of the plurality of channels. The target amplitude response is defined by relationships between amplitude values of the summation and frequency values of the summation. The computing device determines a transfer function of a single-input, multi-output all pass filter based on the target amplitude response and determines coefficients of the allpass filter based on the transfer function. The computing devices processes the monaural channel with the coefficients of the allpass filter to generate the plurality of channels. ## Claims ### Claim 1 A system for generating a plurality of channels from a monaural channel, comprising: one or more computing devices configured to: determine a target amplitude response defining one or more constraints on a summation of the plurality of channels, the target amplitude response being defined by relationships between amplitude values of the summation and frequency values of the summation; determine a transfer function of a single-input, multi-output allpass filter based on the target amplitude response; determine coefficients of the allpass filter based on the transfer function; and process the monaural channel with the coefficients of the allpass filter to generate the plurality of channels. ### Claim 2 (depends on 1) The system of claim 1, wherein the one or more constraints include a target broadband attenuation for the summation of the plurality of channels. ### Claim 3 (depends on 1) The system of claim 1, wherein the one or more constraints include a target subband attenuation for the summation of the plurality of channels. ### Claim 4 (depends on 1) The system of claim 1, wherein the one or more constraints include a critical point defining on curvature of the target amplitude response. ### Claim 5 (depends on 4) The system of claim 4, wherein the critical point defines a frequency at which the target amplitude response −3 dB. ### Claim 6 (depends on 4) The system of claim 4, wherein the critical point defines a frequency at which the target amplitude response is −∞ dB. ### Claim 7 (depends on 1) The system of claim 1, wherein the one or more constraints include a filter characteristic in the summation of the plurality of channels. ### Claim 8 (depends on 7) The system of claim 7, wherein the filter characteristic includes one of: a high-pass filter characteristic; a low-pass filter characteristic; a band-pass filter characteristic; or a band-reject filter characteristic. ### Claim 9 (depends on 1) The system of claim 1, wherein the one or more constraints include a critical point and a filter characteristic. ### Claim 10 (depends on 1) The system of claim 1, wherein the one or more constraints include a target broadband attenuation, a critical point, and a filter characteristic. ### Claim 11 (depends on 1) The system of claim 1, wherein the one or more computing devices configured to determine the coefficients of the allpass filter based on the transfer function includes the one or more computing devices being configured to use an inverse discrete fourier transform (idft). ### Claim 12 (depends on 1) The system of claim 1, wherein the one or more computing devices configured to determine the coefficients of the allpass filter based on the transfer function includes the one or more computing devices being configured to use a phase-vocoder. ### Claim 13 (depends on 1) The system of claim 1, wherein the transfer function defines a rotation of a first phase angle of a first channel of the plurality of channels relative to a second phase angle of a second channel of the plurality of channels. ### Claim 14 (depends on 1) The system of claim 1, wherein the one or more computing devices are further configured to combine the plurality of channels into a monaural output channel. ### Claim 15 (depends on 1) The system of claim 1, wherein the one or more computing devices are further configured to provide the plurality of channels to a user device via a network. ### Claim 16 A method for generating a plurality of channels from a monaural channel, comprising, by a circuitry: determining a target amplitude response defining one or more constraints on a summation of the plurality of channels, the target amplitude response being defined by relationships between amplitude values of the summation and frequency values of the summation; determining a transfer function of a single-input, multi-output allpass filter based on the target amplitude response; determining coefficients of the allpass filter based on the transfer function; and processing the monaural channel with the coefficients of the allpass filter to generate the plurality of channels. ### Claim 17 (depends on 16) The method of claim 16, wherein the one or more constraints include a target broadband attenuation for the summation of the plurality of channels. ### Claim 18 (depends on 16) The method of claim 16, wherein the one or more constraints include a target subband attenuation for the summation of the plurality of channels. ### Claim 19 (depends on 16) The method of claim 16, wherein the one or more constraints include a critical point defining on curvature of the target amplitude response. ### Claim 20 (depends on 19) The method of claim 19, wherein the critical point defines a frequency at which the target amplitude response −3 dB. ### Claim 21 (depends on 19) The method of claim 19, wherein the critical point defines a frequency at which the target amplitude response is −∞ dB. ### Claim 22 (depends on 16) The method of claim 16, wherein the one or more constraints include a filter characteristic in the summation of the plurality of channels. ### Claim 23 (depends on 22) The method of claim 22, wherein the filter characteristic includes one of: a high-pass filter characteristic; a low-pass filter characteristic; a band-pass filter characteristic; or a band-reject filter characteristic. ### Claim 24 (depends on 16) The method of claim 16, wherein the one or more constraints include a critical point and a filter characteristic. ### Claim 25 (depends on 16) The method of claim 16, wherein the one or more constraints include a target broadband attenuation, a critical point, and a filter characteristic. ### Claim 26 (depends on 16) The method of claim 16, wherein determining the coefficients of the allpass filter based on the transfer function includes using an inverse discrete fourier transform (idft). ### Claim 27 (depends on 16) The method of claim 16, wherein determining the coefficients of the allpass filter based on the transfer function includes using a phase-vocoder. ### Claim 28 (depends on 16) The method of claim 16, wherein the transfer function defines a rotation of a first phase angle of a first channel of the plurality of channels relative to a second phase angle of a second channel of the plurality of channels. ### Claim 29 (depends on 16) The method of claim 16, further comprising, by the processing circuitry, combining the plurality of channels into a monaural output channel. ### Claim 30 (depends on 16) The method of claim 16, further comprising, by the processing circuitry, providing the plurality of channels to a user device via a network. ### Claim 31 A non-transitory computer readable medium comprising stored instructions for generating a plurality of channels from a monaural channel, the instructions that, when executed by at least one processor, configure the at least one processor to: determine a target amplitude response defining one or more constraints on a summation of the plurality of channels, the target amplitude response being defined by relationships between amplitude values of the summation and frequency values of the summation; determine a transfer function of a single-input, multi-output allpass filter based on the target amplitude response; determine coefficients of the allpass filter based on the transfer function; and process the monaural channel with the coefficients of the allpass filter to generate the plurality of channels. ### Claim 32 (depends on 31) The non-transitory computer readable medium of claim 31, wherein the one or more constraints include a target broadband attenuation for the summation of the plurality of channels. ### Claim 33 (depends on 31) The non-transitory computer readable medium of claim 31, wherein the one or more constraints include a target subband attenuation for the summation of the plurality of channels. ### Claim 34 (depends on 31) The non-transitory computer readable medium of claim 31, wherein the one or more constraints include a critical point defining on curvature of the target amplitude response. ### Claim 35 (depends on 34) The non-transitory computer readable medium of claim 34, wherein the critical point defines a frequency at which the target amplitude response −3 dB. ### Claim 36 (depends on 34) The non-transitory computer readable medium of claim 34, wherein the critical point defines a frequency at which the target amplitude response is −∞ dB. ### Claim 37 (depends on 31) The non-transitory computer readable medium of claim 31, wherein the one or more constraints include a filter characteristic in the summation of the plurality of channels. ### Claim 38 (depends on 37) The non-transitory computer readable medium of claim 37, wherein the filter characteristic includes one of: a high-pass filter characteristic; a low-pass filter characteristic; a band-pass filter characteristic; or a band-reject filter characteristic. ### Claim 39 (depends on 31) The non-transitory computer readable medium of claim 31, wherein the one or more constraints include a critical point and a filter characteristic. ### Claim 40 (depends on 31) The non-transitory computer readable medium of claim 31, wherein the one or more constraints include a target broadband attenuation, a critical point, and a filter characteristic. ### Claim 41 (depends on 31) The non-transitory computer readable medium of claim 31, wherein the instructions that configure the at least one processor to determine the coefficients of the allpass filter based on the transfer function configures the at least one processor to use an inverse discrete fourier transform (idft). ### Claim 42 (depends on 31) The non-transitory computer readable medium of claim 31, wherein the instructions that configure the at least one processor to determine the coefficients of the allpass filter based on the transfer function configures the at least one processor to use a phase-vocoder. ### Claim 43 (depends on 31) The non-transitory computer readable medium of claim 31, wherein the transfer function defines a rotation of a first phase angle of a first channel of the plurality of channels relative to a second phase angle of a second channel of the plurality of channels. ### Claim 44 (depends on 31) The non-transitory computer readable medium of claim 31, wherein the instructions further configure the at least one processor to combine the plurality of channels into a monaural output channel. ### Claim 45 (depends on 31) The non-transitory computer readable medium of claim 31, wherein the instructions further configure the at least one processor to provide the plurality of channels to a user device via a network.