# US 9,883,308 B2 · Multichannel audio signal processing method and device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,883,308 B2 - Document ID: US9883308B2 - Status: Granted - Kind: B2 - Application number: 15/323,028 - Filed: 2015-07-01 - Published: 2017-05-11 - Granted: 2018-01-30 - Earliest claimed: 2014-07-01 - Assignees: Electronics and Telecommunications Research Institute - Applicants: Electronics & Telecommunications Research Institute - Inventors: Seung Kwon Beack; Jeong Il Seo; Jong Mo Sung; Tae Jin Lee; Dae Young Jang; Jin Woong Kim - Web page: https://patentgrep.com/patent/US9883308B2 ## CPC - H04S 3/008: {in which the audio signals are in digital form, i.e. employing more than two discrete digital channels (data reduction aspects thereof based on psychoacoustics G10L19/02)} - G10L 19/008: Multichannel audio signal coding or decoding using interchannel correlation to reduce redundancy, e.g. joint-stereo, intensity-coding or matrixing - G10L 19/20: using sound class specific coding, hybrid encoders or object based coding - G10L 19/0204: {using subband decomposition} - H04S 2400/03: Aspects of down-mixing multi-channel audio to configurations with lower numbers of playback channels, e.g. 7.1 -> 5.1 (H04S2400/01 takes precedence) - H04S 2400/07: Generation or adaptation of the Low Frequency Effect [LFE] channel, e.g. distribution or signal processing - H04S: STEREOPHONIC SYSTEMS - G10L: SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING ## Abstract Disclosed are a multi-channel audio signal processing method and a multi-channel audio signal processing apparatus. The multi-channel audio signal processing method may generate N channel output signals from N/2 channel downmix signals based on an N-N/2-N structure. ## Claims ### Claim 1 A method of processing a multi-channel audio signal, the method comprising: identifying a residual signal and N/2 channel downmix signals generated from N channel input signals; applying the N/2 channel downmix signals and the residual signal to a first matrix; outputting a first signal that is input to each of N/2 decorrelators corresponding to N/2 one-to-two (OTT) boxes through the first matrix and a second output signal that is transmitted to a second matrix without being input to the N/2 decorrelators; outputting a decorrelated signal from the first signal through the N/2 decorrelators; applying the decorrelated signal and the second signal to the second matrix; and generating N channel output signals through the second matrix. ### Claim 2 (depends on 1) The method of claim 1, wherein, when a Low Frequency Enhancement (LFE) channel is not included in the N channel output signals, the N/2 decorrelators correspond to the N/2 OTT boxes. ### Claim 3 (depends on 1) The method of claim 1, wherein, when the number of decorrelators exceeds a reference value of a modulo operation, indices of the decorrelators are repeatedly reused based on the reference value. ### Claim 4 (depends on 1) The method of claim 1, wherein, when an LFE channel is included in the N channel output signals, the decorrelators corresponding to the remaining number excluding the number of LFE channels from N/2 are used, and the LTE channel does not use an OTT box decorrelator. ### Claim 5 (depends on 1) The method of claim 1, wherein, when a temporal shaping tool is not used, a single vector including the second signal, the decorrelated signal derived from the decorrelator, and the residual signal derived from the decorrelator is input to the second matrix. ### Claim 6 (depends on 1) The method of claim 1, wherein, when a temporal shaping tool is used, a vector corresponding to a direct signal including the second signal and the residual signal derived from the decorrelator and a vector corresponding to a diffuse signal including the decorrelated signal derived from the decorrelator are input to the second matrix. ### Claim 7 (depends on 6) The method of claim 6, wherein the generating of the N channel output signals comprises shaping a temporal envelope of an output signal by applying a scale factor based on the diffuse signal and the direct signal to a diffuse signal portion of the output signal, when a Subband Domain Time Processing (STP) is used. ### Claim 8 (depends on 6) The method of claim 6, wherein the generating of the N channel output signals comprises flattening and reshaping an envelope corresponding to a direct signal portion for each channel of N channel output signals when a Guided Envelope Shaping (GES) is used. ### Claim 9 (depends on 1) The method of claim 1, wherein a size of the first matrix is determined based on the number of downmix signal channels and the number of decorrelators to which the first matrix is to be applied, and an element of the first matrix is determined based on a Channel Level Difference (CLD) parameter or a Channel Prediction Coefficient (CPC) parameter. ### Claim 10 A method of processing a multi-channel audio signal, the method comprising: identifying N/2 channel downmix signals and N/2 channel residual signals; generating N channel output signals by inputting the N/2 channel downmix signals and the N/2 channel residual signals to N/2 one-to-two (OTT) boxes, wherein the N/2 OTT boxes are disposed in parallel without mutual connection, an OTT box to output a Low Frequency Enhancement (LFE) channel among the N/2 OTT boxes is configured to: (1) receive a downmix signal aside from a residual signal, (2) use a Channel Level Difference (CLD) parameter between the CLD parameter and an Inter channel Correlation/Coherence (ICC) parameter, and (3) not output a decorrelated signal through a decorrelator. ### Claim 11 An apparatus for processing a multi-channel audio signal, the apparatus comprising: a processor configured to perform a multi-channel audio signal processing method, wherein the multi-channel audio signal processing method comprises: identifying a residual signal and N/2 channel downmix signals generated from N channel input signals; applying the N/2 channel downmix signals and the residual signal to a first matrix; outputting a first signal that is input to each of N/2 decorrelators corresponding to N/2 one-to-two (OTT) boxes through the first matrix and a second output signal that is transmitted to a second matrix without being input to the N/2 decorrelators; outputting a decorrelated signal from the first signal through the N/2 decorrelators; applying the decorrelated signal and the second signal to the second matrix; and generating N channel output signals through the second matrix. ### Claim 12 (depends on 11) The apparatus of claim 11, wherein, when a Low Frequency Enhancement (LFE) channel is not included in the N channel output signals, the N/2 decorrelators correspond to the N/2 OTT boxes. ### Claim 13 (depends on 11) The apparatus of claim 11, wherein, when the number of decorrelators exceeds a reference value of a modulo operation, indices of the decorrelators are repeatedly recycled based on the reference value. ### Claim 14 (depends on 11) The apparatus of claim 11, wherein, when the LFE channel is included in the N channel output signals, the decorrelators corresponding to the remaining number excluding the number of LFE channels from N/2 are used, and the LTE channel does not use an OTT box decorrelator. ### Claim 15 (depends on 11) The apparatus of claim 11, wherein, when a temporal shaping tool is not used, a single vector including the second signal, the decorrelated signal derived from the decorrelator, and the residual signal derived from the decorrelator is input to the second matrix. ### Claim 16 (depends on 11) The apparatus of claim 11, wherein, when a temporal shaping tool is used, a vector corresponding to a direct signal including the second signal and the residual signal derived from the decorrelator and a vector corresponding to a diffuse signal including the decorrelated signal derived from the decorrelator are input to the second matrix. ### Claim 17 (depends on 16) The apparatus of claim 16, wherein the generating of the N channel output signals comprises shaping a temporal envelope of an output signal by applying a scale factor based on the diffuse signal and the direct signal to a diffuse signal portion of the output signal, when a Subband Domain Time Processing (STP) is used. ### Claim 18 (depends on 16) The apparatus of claim 16, wherein the generating of the N channel output signals comprises flattening and reshaping an envelope corresponding to a direct signal portion for each channel of N channel output signals when a Guided Envelope Shaping (GES) is used. ### Claim 19 (depends on 11) The apparatus of claim 11, wherein a size of the first matrix is determined based on the number of downmix signal channels and the number of decorrelators to which the first matrix is to be applied, and an element of the first matrix is determined based on a Channel Level Difference (CLD) parameter or a Channel Prediction Coefficient (CPC) parameter. ### Claim 20 An apparatus for processing a multi-channel audio signal, the apparatus comprising: a processor configured to perform a multi-channel audio signal processing method, wherein the multi-channel audio signal processing method comprises: identifying N/2 channel downmix signals and N/2 channel residual signals; generating N channel output signals by inputting the N/2 channel downmix signals and the N/2 channel residual signals to N/2 one-to-two (OTT) boxes, the N/2 OTT boxes are disposed in parallel without mutual connection, and an OTT box to output a Low Frequency Enhancement (LFE) channel among the N/2 OTT boxes is configured to: (1) receive a downmix signal aside from a residual signal, (2) use a Channel Level Difference (CLD) parameter between the CLD parameter and an Inter channel Correlation/Coherence (ICC) parameter, and (3) not output a decorrelated signal through a decorrelator.