# US 10,872,613 B2 · Inter-channel bandwidth extension spectral mapping and adjustment > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,872,613 B2 - Document ID: US10872613B2 - Status: Granted - Kind: B2 - Application number: 16/673,733 - Filed: 2019-11-04 - Published: 2020-02-27 - Granted: 2020-12-22 - Earliest claimed: 2017-03-09 - Assignees: QUALCOMM Incorporated - Applicants: QUALCOMM Incorporated - Inventors: Venkata Subrahmanyam Chandra Sekhar Chebiyyam; Venkatraman Atti - Web page: https://patentgrep.com/patent/US10872613B2 ## CPC - G10L 19/008: Multichannel audio signal coding or decoding using interchannel correlation to reduce redundancy, e.g. joint-stereo, intensity-coding or matrixing - G10L 19/167: {Audio streaming, i.e. formatting and decoding of an encoded audio signal representation into a data stream for transmission or storage purposes} - G10L 21/038: using band spreading techniques - H04R 3/005: {for combining the signals of two or more microphones (specially adapted for hearing aids H04R25/407)} - H04R 3/12: for distributing signals to two or more loudspeakers {(specially adapted for hearing aids H04R25/407)} - H04S 1/007: {in which the audio signals are in digital form (data reduction aspects thereof based on psychoacoustics G10L19/02)} - H04S 5/02: of the pseudo four-channel type, e.g. in which rear channel signals are derived from two-channel stereo signals - G10L 19/0204: {using subband decomposition} - H04S 2400/15: Aspects of sound capture and related signal processing for recording or reproduction - H04S 2420/07: Synergistic effects of band splitting and sub-band processing - G10L: SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING - H04R: LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS (producing sounds with frequency not determined by supply frequency G10K) - H04S: STEREOPHONIC SYSTEMS ## Abstract A method includes generating a synthesized non-reference high-band channel based on a non-reference high-band excitation corresponding to a non-reference target channel. The method further includes estimating one or more spectral mapping parameters based on the synthesized non-reference high-band channel and a high-band portion of the non-reference target channel. The method also includes applying the one or more spectral mapping parameters to the synthesized non-reference high-band channel to generate a spectrally shaped synthesized non-reference high-band channel. The method further includes generating an encoded bitstream based on the one or more spectral mapping parameters and the spectrally shaped synthesized non-reference high-band channel. ## Claims ### Claim 1 A device comprising: an encoder configured to: identify a non-reference target channel based on temporal shift values in a current frame; generate a high-band portion of the non-reference target channel; generate a synthesized non-reference high-band channel based on a non-reference high-band excitation corresponding to the non-reference target channel; generate one or more spectral mapping parameters based on a maximum-likelihood measure applied to the synthesized non-reference high-band channel and the high-band portion of the non-reference target channel; apply the one or more spectral mapping parameters to the synthesized non-reference high-band channel to generate a spectrally shaped synthesized non-reference high-band channel; and generate an encoded bitstream based on the one or more spectral mapping parameters and the spectrally shaped synthesized non-reference high-band channel; and a transmitter configured to transmit the encoded bitstream to a second device. ### Claim 2 (depends on 1) The device of claim 1, wherein the encoder is further configured to: apply a first gain to a harmonic high-band excitation to generate a gain-adjusted harmonic high-band excitation; apply a second gain to modulated noise to generate gain-adjusted modulated noise; and combine the gain-adjusted harmonic high-band excitation and the gain-adjusted modulated noise to generate the non-reference high-band excitation. ### Claim 3 (depends on 1) The device of claim 1, wherein the synthesized non-reference high-band channel is generated using a linear prediction coefficient synthesis filter. ### Claim 4 (depends on 1) The device of claim 1, wherein the encoder is further configured to filter the synthesized non-reference high-band channel based on a spectral-mapping filter. ### Claim 5 (depends on 1) The device of claim 1, wherein the encoder is further configured to estimate a gain mapping parameter based on the spectrally shaped synthesized non-reference high-band channel, the gain mapping parameter distinct from the one or more spectral mapping parameters. ### Claim 6 (depends on 5) The device of claim 5, wherein the gain mapping parameter is further based on a high-band mid channel, a synthesized high-band mid channel, and a non-reference high-band channel. ### Claim 7 (depends on 1) The device of claim 1, wherein the one or more spectral mapping parameters are estimated based on a first autocorrelation value of the non-reference target channel at lag index one and a second autocorrelation value of the non-reference target channel at lag index zero. ### Claim 8 (depends on 1) The device of claim 1, wherein the one or more spectral mapping parameters include a spectral mapping parameter corresponding to a criteria satisfied by at least two spectral mapping parameter candidates to match a spectral shape of the non-reference target channel and a spectral shape of the spectrally shaped synthesized non-reference high-band channel. ### Claim 9 (depends on 8) The device of claim 8, wherein the spectral mapping parameter corresponds to a spectral mapping parameter of a previous frame if the at least two spectral mapping parameter candidates are non-real candidates. ### Claim 10 (depends on 8) The device of claim 8, wherein the spectral mapping parameter corresponds to a spectral mapping parameter of a previous frame if each spectral mapping parameter candidate of the at least two spectral mapping parameter candidates has an absolute value that is greater than one. ### Claim 11 (depends on 8) The device of claim 8, wherein the spectral mapping parameter corresponds to a spectral mapping parameter candidate having an absolute value less than one if only one spectral mapping parameter candidate of the at least two spectral mapping parameter candidates has an absolute value less than one. ### Claim 12 (depends on 8) The device of claim 8, wherein the spectral mapping parameter corresponds to a spectral mapping parameter candidate having a smallest value if more than one of the at least two spectral mapping parameter candidates have an absolute value less than one. ### Claim 13 (depends on 8) The device of claim 8, wherein the spectral mapping parameter corresponds to a spectral mapping parameter of a previous frame if more than one of the at least two spectral mapping parameter candidates have an absolute value less than one. ### Claim 14 (depends on 1) The device of claim 1, wherein the encoded bitstream corresponds to an inter-channel bandwidth extension (ICBWE) bitstream, the ICBWE bitstream based on a high-band reference channel indicator bitstream, a high-band spectral mapping bitstream, and a high-band gain mapping bitstream. ### Claim 15 (depends on 1) The device of claim 1, wherein the encoder is further configured to: generate a reference channel indicator based on a temporal mismatch between a first audio channel and a second audio channel; and select, based on the reference channel indicator, the first audio channel or the second audio channel as the non-reference target channel. ### Claim 16 (depends on 1) The device of claim 1, wherein the encoder and the transmitter are integrated into a mobile device. ### Claim 17 (depends on 1) The device of claim 1, wherein the encoder and the transmitter are integrated into a base station. ### Claim 18 A method of encoding audio data, the method comprising: identifying a non-reference target channel based on temporal shift values in a current frame; generating a synthesized non-reference high-band channel based on a non-reference high-band excitation corresponding to the non-reference target channel; estimating one or more spectral mapping parameters based on a maximum-likelihood measure applied to the synthesized non-reference high-band channel and a high-band portion of the non-reference target channel; applying the one or more spectral mapping parameters to the synthesized non-reference high-band channel to generate a spectrally shaped synthesized non-reference high-band channel; generating an encoded bitstream based on the one or more spectral mapping parameters and the spectrally shaped synthesized non-reference high-band channel; and transmitting the encoded bitstream to a second device. ### Claim 19 (depends on 18) The method of claim 18, further comprising: applying a first gain to a harmonic high-band excitation to generate a gain-adjusted harmonic high-band excitation; applying a second gain to modulated noise to generate gain-adjusted modulated noise; and combining the gain-adjusted harmonic high-band excitation and the gain-adjusted modulated noise to generate the non-reference high-band excitation. ### Claim 20 (depends on 18) The method of claim 18, further comprising generating the synthesized non-reference high-band channel based on a linear prediction coefficient synthesis filter. ### Claim 21 (depends on 18) The method of claim 18, wherein the one or more spectral mapping parameters include a spectral mapping parameter corresponding to a criteria satisfied by at least two spectral mapping parameter candidates to match a spectral shape of the non-reference target channel and a spectral shape of the spectrally shaped synthesized non-reference high-band channel. ### Claim 22 (depends on 21) The method of claim 21, wherein the spectral mapping parameter corresponds to a spectral mapping parameter of a previous frame if the at least two spectral mapping parameter candidates are non-real candidates. ### Claim 23 (depends on 21) The method of claim 21, wherein the spectral mapping parameter corresponds to a spectral mapping parameter of a previous frame if each spectral mapping parameter candidate of the at least two spectral mapping parameter candidates has an absolute value that is greater than one. ### Claim 24 (depends on 21) The method of claim 21, wherein the spectral mapping parameter corresponds to a spectral mapping parameter candidate having an absolute value less than one if only one spectral mapping parameter candidate of the at least two spectral mapping parameter candidates has an absolute value less than one. ### Claim 25 (depends on 21) The method of claim 21, wherein the spectral mapping parameter corresponds to a spectral mapping parameter candidate having a smallest value if more than one of the at least two spectral mapping parameter candidates have an absolute value less than one. ### Claim 26 (depends on 21) The method of claim 21, wherein the spectral mapping parameter corresponds to a spectral mapping parameter of a previous frame if more than one of the at least two spectral mapping parameter candidates have an absolute value less than one. ### Claim 27 (depends on 18) The method of claim 18, wherein estimating the one or more spectral mapping parameters and applying the one or more spectral mapping parameters are performed at a mobile device. ### Claim 28 (depends on 18) The method of claim 18, wherein estimating the one or more spectral mapping parameters and applying the one or more spectral mapping parameters are performed at a base station. ### Claim 29 A device comprising: means for identifying a non-reference target channel based on temporal shift values in a current frame; means for generating a high-band portion of the non-reference target channel; means for generating a synthesized non-reference high-band channel based on a non-reference high-band excitation corresponding to the non-reference target channel; means for estimating one or more spectral mapping parameters based on a maximum-likelihood measure applied to the synthesized non-reference high-band channel and the high-band portion of the non-reference target channel; means for applying the one or more spectral mapping parameters to the synthesized non-reference high-band channel to generate a spectrally shaped synthesized non-reference high-band channel; means for generating an encoded bitstream based on the one or more spectral mapping parameters and the spectrally shaped synthesized non-reference high-band channel; and means for transmitting the encoded bitstream to a second device. ### Claim 30 (depends on 29) The device of claim 29, wherein the means for estimating the one or more spectral mapping parameters and the means for applying the one or more spectral mapping parameters are integrated into a mobile device. ### Claim 31 (depends on 29) The device of claim 29, wherein the means for estimating the one or more spectral mapping parameters and the means for applying the one or more spectral mapping parameters are integrated into a base station. ### Claim 32 A device comprising: a decoder configured to: generate a reference channel and a non-reference target channel from a received low-band bitstream, the low-band bitstream received from an encoder of a second device; identify a non-reference target channel based on temporal shift values in a current frame; generate a synthesized non-reference high-band channel based on a maximum-likelihood measure applied to the non-reference high-band excitation corresponding to the non-reference target channel; extract one or more spectral mapping parameters from a received spectral mapping bitstream, the spectral mapping bitstream received from the encoder of the second device; generate a spectrally shaped synthesized non-reference high-band channel by applying the one or more spectral mapping parameters to the synthesized non-reference high-band channel; and generate an output signal based at least on the spectrally shaped synthesized non-reference high-band channel, the reference channel, and the non-reference target channel. ### Claim 33 (depends on 32) The device of claim 32, further comprising a playback device configured to render the output signal. ### Claim 34 (depends on 32) The device of claim 32, wherein the encoder is further configured to: scale the spectrally shaped synthesized non-reference high-band channel based on a quantized high-band gain shape to generate a scaled signal; and generate a decoded high-band non-reference channel based on the scaled signal, wherein the output signal is based at least on the decoded high-band non-reference channel. ### Claim 35 (depends on 32) The device of claim 32, wherein the decoder is integrated into a mobile device. ### Claim 36 (depends on 32) The device of claim 32, wherein the decoder is integrated into a base station.