WO2016133366A1

WO2016133366A1 - Multichannel signal processing method, and multichannel signal processing apparatus for performing same

Info

Publication number: WO2016133366A1
Application number: PCT/KR2016/001613
Authority: WO
Inventors: 백승권; 서정일; 성종모; 이태진; 장대영; 최진수
Original assignee: 한국전자통신연구원
Priority date: 2015-02-17
Filing date: 2016-02-17
Publication date: 2016-08-25

Abstract

Disclosed are a multichannel signal encoding method, an encoding apparatus for performing the encoding method, a multichannel signal processing method, and a decoding apparatus for performing a decoding method. The decoding method comprises the steps of: identifying a downmix signal of an N/2 channel which has been derived from an input signal of an N channel; and generating an output signal of the N channel from the downmix signal of the identified N/2 channel by using a plurality of OTT boxes. The number of the plurality of OTT boxes may be the same as N/2 which is the number of channels of the downmix signal, if there is no LFE channel in the output signal.

Description

Multi-channel signal processing method and multi-channel signal processing device performing the method

The present invention relates to a multi-channel signal processing method and a multi-channel signal processing apparatus for performing the method, and more particularly to a method and apparatus that can be compressed without deterioration of sound quality even if the number of channels of the multi-channel signal increases.

MPS (MPEG Surround) is a codec for coding multichannel signals such as 5.1 channel and 7.1 channel. By MPS, multi-channel signals can be compressed and transmitted at a high compression rate.

However, the encoding / decoding process has a limitation of backward compatibility. In other words, the bitstream of the multi-channel signal generated through the MPS is required to be backward compatible to be reproduced in mono or stereo format through the existing codec.

Therefore, even if a multi-channel signal having more than the number of channels defined in the MPS is input to the MPS, the signal output and transmitted from the MPS should be expressed in mono or stereo as in the MPS. The decoder may then recover the multi-channel signal from the bitstream using the additional information received from the encoder. In this case, the decoder may restore the multi-channel signal with additional information for upmixing.

However, as the communication environment improves recently, as the transmission bandwidth increases, the bandwidth allocated to the signal also increases. Therefore, technology is being developed to maintain the sound quality of the original multichannel signal rather than excessively compressing it to correspond to the bandwidth. Even so, in order to process multichannel signals with very large numbers of channels, compression is still required when transmitting.

Therefore, when processing an input signal having a greater number of channels than the number of channels defined in the MPS standard, there is a demand for a method capable of reducing the amount of data through a predetermined level or more while maintaining the quality of a multichannel signal.

The present invention provides a method and apparatus for processing a multichannel signal through an N-N / 2-N structure.

Multi-channel signal processing method according to an embodiment of the present invention comprises the steps of identifying the downmix signal of the N / 2 channel derived from the input signal of the N channel; And generating an N-channel output signal from the identified N / 2 channel downmix signal using a plurality of OTT boxes, wherein the number of the plurality of OTT boxes includes no LFE channel in the output signal. In this case, the number of channels of the downmix signal may be equal to N / 2.

Each of the plurality of OTT boxes may generate an output signal of two channels using an uncorrelated signal generated from a decorrelator corresponding to each of the plurality of OTT boxes and a downmix signal of one channel. .

When the number N of channels of the output signal exceeds a preset channel number M, the decorrelator includes a first decorrelator corresponding to a channel of M or less and a second decorrelator corresponding to more than M channels; The second decorrelator may reuse a filter set of the first decorrelator.

An OTT box whose output is an LFE channel among the plurality of OTT boxes may generate two channels of downmix signals without using an uncorrelated signal.

Each of the plurality of OTT boxes may generate two channel output signals using the residual signal and one channel downmix signal instead of the uncorrelated signal when the transmitted residual signal exists.

The generating of the N-channel output signal may include generating an N-channel output signal using a pre decorrelator matrix M1 and a mix matrix M2.

Each of the plurality of OTT boxes may generate an output signal of N channels using a channel level difference (CLD).

The number N of channels of the output signal may be an even number from 10 to 32.

In accordance with another aspect of the present invention, there is provided a method of processing a multichannel signal, the method including: decoding a downmix signal of an N / 2 channel encoded according to a first coding scheme; And generating an output signal of the N channel from the downmix signal of the N / 2 channel according to a second coding scheme, wherein the second coding scheme, when the output signal does not include an LFE channel, One number of one-to-two (OTT) boxes equal to N / 2, which is the number of channels of the downmix signal, may be used.

The multi-channel signal processing apparatus according to an embodiment of the present invention includes a process for executing a multi-channel signal processing method, wherein the process identifies a downmix signal of the N / 2 channel derived from the input signal of the N channel and And generating an N-channel output signal from the identified N / 2 channel downmix signal using a plurality of OTT boxes, wherein the number of the plurality of OTT boxes is equal to the downmix when the LFE channel is not present in the output signal. It may be equal to N / 2 which is the number of channels of the signal.

The process may generate an output signal of the N channel using a pre decorrelator matrix M1 and a mix matrix M2.

The multi-channel signal processing apparatus according to another embodiment of the present invention includes a process for executing a multi-channel signal processing method, wherein the process decodes the downmix signal of the N / 2 channel encoded according to the first coding scheme and And generating an output signal of the N channel from the downmix signal of the N / 2 channel according to a second coding scheme, wherein the second coding scheme, when the output signal does not include an LFE channel, One number of one-to-two (OTT) boxes equal to the number of channels N / 2 may be used.

According to an embodiment of the present invention, by processing a multi-channel signal according to the N-N / 2-N structure, it is possible to efficiently process a multi-channel signal of a greater number of channels than the number of channels defined in MPS.

1 is a diagram illustrating an encoding apparatus and a decoding apparatus, according to an embodiment.

2 is a diagram illustrating detailed components of an encoding apparatus according to an embodiment.

3 is a diagram illustrating detailed components of an encoding apparatus according to another embodiment.

4 is a diagram for describing an operation of a first encoding unit, according to an exemplary embodiment.

5 is a diagram illustrating detailed components of a decoding apparatus according to an embodiment.

6 is a diagram illustrating detailed components of a decoding apparatus according to another exemplary embodiment.

7 is a diagram for describing an operation of a second decoding unit, according to an exemplary embodiment.

8 is a diagram illustrating a spatial audio processing procedure for an N-N / 2-N structure according to an embodiment.

9 illustrates a tree structure for performing spatial audio processing for the N-N / 2-N structure according to an embodiment.

FIG. 10 illustrates a process of generating an output signal of 24 channels from a 12-channel downmix according to an embodiment.

FIG. 11 illustrates an OTT box of the process of FIG. 10, according to an exemplary embodiment.

FIG. 12 illustrates a process of FIG. 11 according to an MPS standard according to an embodiment.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. According to the present invention, an N / 2 channel downmix signal is generated from an N channel input signal through an MPS encoder, and an N / 2 output signal is generated using an N / 2 channel downmix signal through an MPS decoder. Explain the process. At this time, the N / 2 channel represents more channels than the number of channels defined in the existing MPS standard. For example, the MPS decoder according to an embodiment of the present invention may satisfy the extended MPS standard for the MPEG-H 3D AUDIO standard.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In the present invention, the encoding apparatus and the decoding apparatus correspond to the multichannel signal processing apparatus.

According to an embodiment of the present invention, the encoding apparatus 100 may generate an N / 2 channel downmix signal by downmixing an N channel input signal. Then, the decoding apparatus 101 may generate an output signal of the N channel by using the downmix signal of the N / 2 channel. Here, N may be 10 or more.

Referring to FIG. 2, the encoding apparatus may include a first encoding unit 201, a sampling rate converter 202, and a second encoding unit 203. The first encoding unit 201 is defined as an MPS encoder. The second encoding unit 203 is defined as a USAC (Unified Speech and Audio Codec) encoder. That is, an N / 2 channel downmix signal may be generated by downmixing an input signal of N channels.

Then, the sampling rate converter 202 may convert the sampling rate for the downmix signal of the N / 2 channel. The sampling rate converter 202 may downsample the bit rate based on the bitrate allocated to the USAC encoder, which is the second encoder 203. If a sufficiently high bitrate is allocated to the USAC encoder, which is the second encoding unit 203, the sampling rate converter 202 may be bypassed.

Thereafter, the second encoding unit 203 may encode the core band of the downmix signal of the N / 2 channel whose sampling rate is converted. Then, the downmix signal of the N / 2 channel encoded through the second encoder 203 may be generated. The encoded downmix signal of the N / 2 channel may be a signal of the M channel (M is equal to or smaller than N / 2). Here, when the frequency band is extended through SBR (Spectral Band Replication) applied in the USAC encoder, the core band means a low frequency band in which the frequency band is not extended.

According to the existing MPS standard, the number of channels of the downmix signal output through the MPS encoder corresponding to the first encoding unit 201 is limited to one channel, two channels, and 5.1 channels. However, the first encoding unit 201 according to an embodiment of the present invention may exceed the number of channels of the downmix signal defined in the MPS standard. That is, the first encoding unit 201 may generate an N / 2 channel downmix signal by downmixing an input signal of N channels. Here, in the N / 2 channel downmix signal, the N / 2 channel may be 1, 2, 5.1, or 5.1 or more.

3 is the same as the component described in FIG. 2, but shows an embodiment in which the order is changed. Specifically, FIG. 2 illustrates an embodiment in which a sampling rate converter 202 exists between the first encoder 201 and the second encoder 203. However, FIG. 3 illustrates an embodiment in which the first encoding unit 302 and the second encoding unit 303 are disposed after the sampling rate converter 301.

4 illustrates a process of generating a downmix signal of N / 2 channels from an input signal of N channels. Referring to FIG. 4, the first encoding unit 401 may include a plurality of TTO boxes 402. Here, each of the plurality of TTO boxes 402 may downmix two input signals and output one downmix signal. That is, the first encoder 401 may include N / 2 TTO boxes 402 to downmix the input signals of the N channels input as shown in FIG. 4 to generate the downmix signals of the N / 2 channels. Can be.

If the first encoder 401 conforms to the existing MPS standard, the downmix signal generated by the first encoder 401 may be one channel, two channels, or 5.1 channels. However, according to an embodiment of the present invention, the first encoding unit 401 may generate an N / 2 channel downmix signal from the N channel input signal according to the MPS. Here, the N / 2 channel may be a channel of 5.1 channels or more as well as 1 channel, 2 channels or 5.1 channels. In this case, when the N channel is larger than the channel defined in the MPS, the first encoding unit 401 needs to consider an additional syntax to control the MPS. For example, the first encoding unit 401 may define an additional syntax for controlling the MPS by using a coding mode using an arbitrary tree.

5 shows a process of generating an output signal of the N channel from the downmix signal of the N / 2 channel. Referring to FIG. 5, the decoding apparatus may include a first decoding unit 501, a sampling rate converter 502, and a second decoding unit 503. The first decoding unit 501 may reconstruct the downmix signal of the N / 2 channel by decoding the encoded downmix signal of the N / 2 channel. Here, the first decoding unit 501 may be defined as a USAC decoder.

The sampling rate converter 502 may convert the sampling rate of the downmix signal of the N / 2 channel. In this case, the sampling rate converter 502 may convert the sampling rate of the audio signal converted by the encoding apparatus to the original sampling rate. In other words, when the sampling rate conversion is performed in FIG. 2 or FIG. 3, the sampling rate conversion unit 502 operates. If the sampling rate conversion is not performed in FIG. 2 or FIG. 3, the sampling rate conversion unit 502 may be bypassed without operation.

Meanwhile, the second decoding unit 503 may generate an N-channel output signal by upmixing the N / 2 channel downmix signal output from the sampling rate converter 502.

The downmix signal input to the conventional MPS decoder is limited to one channel, two channels, and 5.1 channels. However, the downmix signal input to the second decoding unit 503 according to an embodiment of the present invention may be extended to N / 2 channels as well as 1 channel, 2 channels, and 5.1 channels. Then, the second decoding unit 503 may generate the N-channel output signal by upmixing the N / 2 channel downmix signal. Here, since the N / 2 channel downmix signal input to the second decoding unit 503 means at least 5.1 channel or more, N may be 10.2 or more channels.

Unlike FIG. 5, FIG. 6 may process an audio signal in the order of the first decoding unit 601, the second decoding unit 602, and the sampling rate converter 603. The first decoding unit 601 may restore the downmix signal of the N / 2 channel. Then, the second decoding unit 602 may generate the output signal of the N channel by upmixing the downmix signal of the N / 2 channel. Thereafter, the sampling rate converter 603 may convert the sampling rate of the output signal of the N channel generated through the second decoder 602.

The second decoding unit 701 described with reference to FIGS. 5 and 6 may generate an output signal of the N channel by upmixing the downmix signal of the N / 2 channel. In this case, the second decoding unit 701 may include a plurality of OTT boxes 702. The OTT box 702 may generate two channels of output signals in stereo form by upmixing one channel of downmix signals.

Accordingly, the second decoding unit 701 generates N / 2 OTT boxes 702 in order for the second decoding unit 701 to upmix the N / 2 channel downmix signal to generate the N channel output signal. It may include.

If the second decoding unit 701 conforms to the existing MPS standard, the number of channels of the downmix signal input to the second decoding unit 701 and processed may be one channel, two channels, or 5.1 channels. However, according to an embodiment of the present invention, the second decoding unit 701 may generate an output signal of the N channel according to the MPS from the downmix signal of the N / 2 channel. Here, N may be 10.2 or more.

In this case, the second decoding unit 701 needs to consider additional syntax to control the MPS. For example, the second decoding unit 701 may define an additional syntax for controlling the MPS by using a coding mode using an arbitrary tree.

The MPS decoder illustrated in FIGS. 8 to 12 is related to the second decoding unit 503 of FIG. 5 and the second decoding unit 602 of FIG. 6.

8 illustrates a process of processing a multichannel signal according to an N-N / 2-N configuration.

8 shows an N-N / 2-N structure in which the structure defined in MPEG SURROUND is changed. In the case of MPEG SURROUND, spatial synthesis may be performed in a decoder as shown in Table 1. Spatial synthesis can transform the input signals from the time domain into a non-uniform subband domain through a hybrid Quadrature Mirror Filter (QMF) analysis bank. Here, the term irregular corresponds to a hybrid.

The decoder then operates in the hybrid subband. The decoder may generate an output signal from the input signals by performing spatial synthesis based on the spatial parameters passed by the encoder. The decoder can then use the hybrid QMF synthesis bank to inverse the output signals from the hybrid subband to the time domain.

8 illustrates a process of processing a multi-channel signal through a mixed matrix of spatial synthesis performed by a decoder. Basically, MPEG SURROUND defines a 5-1-5 structure, a 5-2-5 structure, a 7-2-7 structure, and a 7-5-7 structure, but the present invention proposes an N-N / 2-N structure.

In the case of the N-N / 2-N structure, after the input signal of the N channel is converted to the downmix signal of the N / 2 channel, the output signal of the N channel is generated from the downmix signal of the N / 2 channel. The decoder according to an embodiment of the present invention may generate the N-channel output signal by upmixing the N / 2 channel downmix signal. Basically, the number of N channels in the N-N / 2-N structure of the present invention is not limited. That is, the N-N / 2-N structure may support not only a channel structure supported by the MPS but also a channel structure of a multichannel signal not supported by the MPS.

In FIG. 8, N / 2 means the number of channels of the downmix signal derived through the MPS. NumInCh means the number of channels of the downmix signal, NumOutCh means the number of channels of the output signal. Specifically, NumInCh, which is the number of channels of the downmix signal, is N / 2. In other words, NumInCh is N / 2 and NumOutCh is N.

In FIG. 8, the downmix signals X ₀ to X _NumInch ₋ ₁ and the residual signals res of the N / 2 channels form an input vector X. In FIG. 8, since NumInCh is N / 2, X ₀ to X _NumInCh ₋ ₁ represent downmix signals of N / 2 channels. Since the number of one-to-two (OTT) boxes is N / 2, N, the number of channels of the output signal, must be even to process the downmix signal of the N / 2 channel. According to an embodiment of the present invention, N may be from 10 to 32.

In FIG. 8, the decorrelators, uncorrelated signals, and residual signals labeled from 1 to M (NumInCh-NumLfe) correspond to different OTT boxes. The reconstruction process for the multi-channel signal to which the N-N / 2-N structure is applied can be visualized in a tree structure.

Vector corresponding to matrix M1

The input vector X to be multiplied by means a vector including the downmix signal of the N / 2 channel. When the low frequency effect (LFE) channel is not included in the output signal of the N channel in the output signal of the N channel, the number of decorrelators generating the uncorrelated signal may be N / 2 at the maximum. However, if N, the channel number of the output signal, exceeds 20, the filters of the decorrelator can be reused.

In order to ensure orthogonality of the output signals of the decorrelator, some N decorator indexes are repeated because N is 20, the number of available decorrelators needs to be limited to a certain number (ex. 10). Can be. Therefore, according to a preferred embodiment of the present invention, N, which is the number of channels of the output signal in the N-N / 2-N structure, needs to be less than twice the limited specific number (ex. N <20). If the LFE channel is included in the output signal, the N channel needs to be configured with a smaller number of channels (eg, N <24) than more than twice the specific number in consideration of the number of LFE channels.

And, the output result of the decorrelators may be replaced with the residual signal for a specific frequency region depending on the bitstream. If the LFE channel is one of the outputs of the OTT box, no decorrelator is used for the OTT box based on the upmix.

In FIG. 8, the decorrelators labeled M (ex. NumInCh-NumLfe) from 1, the output result of the decorrelator (uncorrelated signal), and residual signals correspond to different OTT boxes. d ₁ ~ d _M means uncorrelated signal which is the output result of the decorrelator (D ₁ ~ D _M ), res ₁ ~ res _M means the residual signal which is the output result of the decorrelator (D ₁ ~ D _M ) do. The decorrelators D1 to DM correspond to different OTT boxes, respectively.

In the following, vectors and matrices used in the NN / 2-N structure are defined. Input signals to decorators in N-2 / NN structures are vectors

Is defined as

vector

Can be determined differently depending on whether a temporal shaping tool is used or not.

(1) When a term shaping tool is not used

Vector if no temporal shaping tool is used

Is based on Equation 1

Corresponding to matrix M1

Is derived by. And,

Is the matrix of the first column in the Nth row.

In this case, the vector in Equation 1

Of elements in

To

May be input directly to the matrix M2 without being input to the N / 2 decorrelators corresponding to the N / 2 OTT boxes. so,

To

May be defined as a direct signal. And vector

Of elements in

To

Signals other than

To

) May be input to the N / 2 decorrelators corresponding to the N / 2 OTT boxes.

vector

Is composed of a direct signal, d ₁ to d _M which are decorrelated signals output from decorrelators, and res ₁ to res _{M which} are residual signals output from decorrelators. vector

May be determined by Equation 2 below.

In equation (2)

Defined as

Is

Means a set of all k satisfying And,

Signal

Fall decorator

When input to, it means the uncorrelated signal output from the decorator. Especially,

Is the OTT box is OTTx and the residual signal is

In the case of means the signal output from the decorator.

The subbands of the output signal can be defined dependently for all time slots n and all hybrid subbands k. Output signal

Can be determined by Equation 3 through the vector w and the matrix M2 .

here,

Denotes a matrix M2 composed of NumOutCh rows and NumInCh-NumLfe columns.

Is

Can be defined by Equation 4 below.

here,

Is defined as And,

Can be smoothed according to Equation 5 below.

here,

Denotes a function where the first row is hybrid band k and the second row is the corresponding processing band.

Corresponds to the last parameter set of the previous frame.

Meanwhile,

By means the hybrid subband signals that can be synthesized in the time domain through the hybrid synthesis filter bank. Here, the hybrid synthesis filter bank is a combination of the QMF synthesis bank through the Nyquist synthesis banks,

Can be transformed from the hybrid subband domain to the time domain through a hybrid synthesis filterbank.

(2) when temporal shaping tools are used

If temporal shaping tools are used, vectors

Is the same as described above, but the vector

May be divided into two vectors as shown in Equations 6 and 7 below.

Denotes a direct signal input directly to the matrix M2 and residual signals output from the decorrelator without passing through the decorrelators,

Means uncorrelated signal output from the decorrelator. And,

Is defined as

Is

Means a set of all k satisfying Also, decorator

Input signal to

Is entered,

Decorator

Means the uncorrelated signal output from.

As defined in Equation 6 and Equation 7.

Wow

The final output signal is

Wow

It can be divided into.

Includes a direct signal,

Includes a diffuse signal. In other words,

Is the result derived from the direct signal input directly to the matrix M2 without passing through the decorrelator,

Is the result derived from the spread signal output from the decorrelator and input to the matrix M2.

If Subband Domain Temporal Processing (STP) is used for the NN / 2-N structure, Guided Envelope Shaping (GES) is used for the NN / 2-N structure. Separately

Wow

Is derived. At this time,

Wow

Is identified by the datastream element bsTempShapeConfig.

In order to synthesize the degree of decorrelation between the channels of the output signal, a spreading signal is generated through the decorrelator for spatial synthesis. In this case, the generated spread signal may be mixed with the direct signal. In general, the temporal envelope of the spread signal does not match the envelope of the direct signal.

At this time, subband domain time processing is used to shape the envelope of each spreading signal portion of the output signal to match the temporal shape of the downmix signal transmitted from the encoder. Such processing may be implemented with envelope estimation, such as envelope ratio calculation for direct and spread signals or shaping of the upper spectral portion of the spread signal.

That is, the temporal energy envelope of the portion corresponding to the direct signal and the portion corresponding to the spread signal in the output signal generated through upmixing can be estimated. The shaping factor may be calculated as the ratio between the temporal energy envelope for the portion corresponding to the direct signal and the portion corresponding to the spread signal.

STP

May be signaled as. if,

If, the spread signal portion of the output signal generated through upmixing can be processed via STP.

On the other hand, in order to reduce the need for delay alignment of the transmitted original downmix signal relative to the spatial upmix for generating the output signal, the downmix of the spatial upmix is approximated with the transmitted original downmix signal ( approximation).

For the N-N / 2-N structure, the direct downmix signal for (NumInCh-NumLfe) may be defined by Equation 8 below.

here,

Includes a pair-wise output signal corresponding to channel d of the output signal for the NN / 2-N structure.

May be defined as shown in Table 2 below for the NN / 2-N structure.

The envelopes of the downmix broadband envelopes and the spread signal portion of each upmix channel can be estimated using Equation 9 below using normalized direct energy.

here,

Means a bandpass factor,

Denotes a spectral flattering factor.

Since there is a direct signal for NumInCh-NumLfe in the NN / 2-N structure,

Energy of the direct signal satisfying

Can be obtained in the same manner as the 5-1-5 structure defined in MPEG Surround. The scale factor for the final envelope process may be defined as in Equation 10 below.

In Equation 10, the scale factor for the NN / 2-N structure

Can be defined. The scale factor is then applied to the spread signal portion of the output signal, thereby mapping the temporal envelope of the output signal to substantially the temporal envelope of the downmix signal. Then, the spread signal portion processed by the scale factor in each channel of the output signals of the N channels may be mixed with the direct signal portion. Then, it may be signaled whether the extension signal portion has been processed in the scale factor for each channel of the output signal. (

) Indicates that the extension signal portion was processed with the scale factor.)

When temporal shaping is performed on the extended signal portion of the output signal described above, characteristic distortion may occur. Thus, Guided Envelope Shaping (GES) can improve temporal / spatial quality while solving distortion problems. The decoder processes the direct signal portion and the extension signal portion of the output signal separately, but when GES is applied, only the direct signal portion of the upmixed output signal can be changed.

GES can recover the broadband envelope of the synthesized output signal. GES includes a modified upmixing process after flattening and reshaping the envelope for the direct signal portion for each channel of the output signal.

For reshaping, additional information of a parametric broadband envelope included in the bitstream may be used. The additional information includes the envelope ratio of the envelope of the original input signal and the envelope of the downmix signal. The envelope ratio at the decoder may be applied to the direct signal portion of each time slot included in the frame for each channel of the output signal. The GES does not alter the spread signal portion for each channel of the output signal.

if,

If, the GES process may proceed. If GES is available, the extension signal and the direct signal of the output signal may be respectively synthesized using the post mixing matrix M2 modified in the hybrid subband domain according to Equation 11 below.

In Equation 11, the direct signal portion for the output signal y provides the direct signal and the residual signal, and the extension signal portion for the output signal y provides the extension signal. In total, only the direct signal can be processed by the GES.

The result of processing the GES may be determined according to Equation 12 below.

The GES can extract an envelope for a particular channel of the upmixed output signal from the downmix signal by the downmix signal and decoder that performs spatial synthesis except the LFE channel depending on the tree structure.

Output signal in NN / 2-N structure

May be defined as shown in Table 3 below.

And, the input signal in the NN / 2-N structure

May be defined as shown in Table 4 below.

Also, downmix signals in NN / 2-N structures

May be defined as shown in Table 5 below.

In the following, the matrix M1 (defined for all time slots n and all hybrid subbands k)

) And the matrix M2 (

) Will be described. These matrices are defined for a given parameter time slot and given processing band m based on the parameter time slot and the CLD, ICC and CPC parameters valid for the processing band.

And

Interpolated version of.

Corresponding to matrix M1 in the NN / 2-N structure of FIG. 8

Describes how the downmix signal is input to the decorrelators used in the decoder. Matrix M1 may be expressed as a free matrix.

The size of the matrix M1 depends on the number of channels of the downmix signal input to the matrix M1 and the number of decorrelators used in the decoder. On the other hand, the elements of the matrix M1 may be derived from the CLD and / or CPC parameters. M1 may be defined by Equation 13 below.

At this time,

Is defined as

Meanwhile,

Can be smoothed by the following equation (14).

here,

Wow

First row in the hybrid subband

Where the second row is the processing band and the third row is the specific hybrid subband

Is a complex conjugation of

to be. And,

Means the last parameter set of the previous frame.

Matrix for Matrix M1

May be defined as follows.

(1) matrix R1

matrix

May control the number of signals input to the decorrelators. Since it does not add uncorrelated signals, it can only be expressed as a function of CLD and CPC.

matrix

May be defined differently according to the channel structure. In the NN / 2-N structure, in order to prevent OTT boxes from being cascaded, all channels of an input signal may be input in pairs by 2 channels to the OTT box. So, for the NN / 2-N structure, the number of OTT boxes is N / 2.

In this case, the matrix

Is a vector containing the input signal

It depends on the number of OTT boxes equal to its column size. However, Lfe upmixes based on OTT boxes are not considered in the NN / 2-N architecture since no decorrelator is needed. matrix

All elements of may be either 1 or 0.

In the NN / 2-N structure

May be defined by Equation 15 below.

All OTT boxes in the NN / 2-N architecture represent a parallel processing satge, not a cascade. Therefore, all OTT boxes in the NN / 2-N structure are not connected to any other OTT boxes. So, matrix is unit matrix

And unit matrix

It can be configured as. In this case, the unit matrix

May be a unit matrix of size N * N.

(2) Matrix G1

In order to handle downmix signals or externally supplied downmix signals prior to MPEG Surround decoding, a datastream controlled by correction factors may be applied. Calibration factor matrix

It can be applied to the downmix signal or an externally supplied downmix signal.

matrix

May ensure that the level of the downmix signal for a particular time frequency tile represented by the parameter is the same as the level of the downmix signal obtained when the spatial parameter is estimated at the encoder.

This is divided into three cases: (i) without external downmix compensation (

), (ii) with parameterized external downmix compensation (

And (iii) perform residual coding based on external downmix compensation (

) Can be separated. if,

If, the decoder does not support residual coding based on external downmix compensation.

And, if external downmix compensation is not applied in the NN / 2-N structure (

), Matrix in NN / 2-N structure

May be defined by Equation 16 below.

here,

Means a unit matrix indicating NumInch * NumInCh size,

Denotes a zero matrix representing NumInch * NumInCh size.

In contrast, if external downmix compensation is applied in the NN / 2-N structure (

), For the NN / 2-N structure

May be defined by Equation 17 below.

here,

Is defined as

On the other hand, when residual coding based on external downmix compensation is applied in the NN / 2-N structure (

),

May be defined by Equation 18 below.

here,

It can be defined as. And,

Can be updated.

(3) matrix H1

In the NN / 2-N structure, the number of channels of the downmix signal may be more than five. Thus, the inverse matrix H is a vector of input signals for all parameter sets and processing bands.

It may be a unit matrix having the same size as the number of columns of.

In NN / 2-N structure, matrix M2

Defines how to combine the direct and uncorrelated signals to regenerate the multi-channel output signal.

May be defined by Equation 19 below.

here,

Is defined as

Meanwhile,

Can be smoothed by the following equation (20).

here,

Wow

First row in the hybrid subband

About

Complex conjugation of

to be. And,

Means the last parameter set of the previous frame.

Matrix for Matrix M2

The element of can be calculated from the equivalent model of the OTT box. The OTT box includes a decorrelator and a mixing section. The mono input signal input to the OTT box is transmitted to the decorrelator and the mixing unit, respectively. The mixing unit may generate a stereo output signal using a mono input signal, an uncorrelated signal output through the decorrelator, and the CLD and ICC parameters. Here, the CLD controls localization in the stereo field, and the ICC controls the stereo wideness of the output signal.

Then, the result output from any OTT box can be defined by Equation 21 below.

OTT box

Labeling as (

),

Time slot for OTT box

And parameter bands

Denotes an element of an arbitrary matrix.

In this case, the post gain matrix may be defined as in Equation 22 below.

here,

, And

,ego,

And

Is defined as

Meanwhile,

(

for

Can be defined as

And,

Is defined as

At this time, in the NN / 2-N structure,

May be defined by Equation 23 below.

Here, CLD and ICC may be defined by Equation 24 below.

At this time,

It can be defined as.

In the N-N / 2-N structure, decorrelators may be performed by a reverberation filter in the QMF subband domain. Reverberation filters exhibit different filter characteristics based on which hybrid subband currently corresponds to all hybrid subbands.

The reverberation filter is an IIR grating filter. The IIR grating filters have different filter coefficients for different decorrelators to produce mutually uncorrelated orthogonal signals.

The uncorrelated process carried out by the decorator is carried out in several processes. First, the output of matrix M1

Is entered into the set of all-pass uncorrelated filters. The filtered signals can then be energy shaped. Here, energy shaping is shaping the spectral or temporal envelope to match uncorrelated signals more closely to the input signal.

Input signal input to any decorator

Vector

It is part of. In order to ensure orthogonality between uncorrelated signals derived through the plurality of decorrelators, the plurality of decorrelators have different filter coefficients.

The uncorrelated filter consists of a plurality of all-pass (IIR) regions preceded by a fixed frequency-dependent delay. The frequency axis may be divided into different regions so as to correspond to the QMF division frequency. In each region, the length of the delay and the length of the filter coefficient vectors are the same. And, the filter coefficients of the decorrelator with fractional delay due to additional phase rotation depend on the hybrid subband index.

As discussed above, the filters of the decorrelators have different filter coefficients to ensure orthogonality between the uncorrelated signals output from the decorrelators. In the N-N / 2-N structure, N / 2 decorrelators are required. At this time, in the N-N / 2-N structure, the number of decorrelators may be limited to ten. In the NN / 2-N structure where Lfe mode does not exist, when the number of OTT boxes, N / 2, exceeds 10, the decorators are more than 10 OTT boxes according to 10 basis modulo operations. It can be reused corresponding to the number of.

Table 6 below shows the index of the uncorrelator in the decoder of the NN / 2-N structure. Referring to Table 6, the N / 2 decorrelators are indexed by 10 units. That is, the 0th decorator and the 10th decorator

Have the same index. In detail, when the number of channels of the output signal exceeds the NDL preset channel number M, the decorrelator may include a first decorrelator corresponding to a channel less than or equal to M and a second decorrelator corresponding to more than M channels. Can be. In addition, the second decorrelator may reuse the filter set of the first decorrelator.

For the N-N / 2-N structure, it may be implemented by the syntax of Table 7.

At this time, bsTreeConfig may be implemented by Table 8. At this time, bsTreeConfig may be implemented by Table 8. According to Table 8, when bsTreeConfig is 7, the configuration of the decoding apparatus of the N-N / 2-N structure according to an embodiment of the present invention. The number of OTT boxes numOttBoxes is equal to the number of channels NumInCh of the downmix signal. And the number of TTT boxes is zero.

At this time, when bsTreeConfig is 0, 1, 2, 3, 4, 5, 6, Table 40 of the MPS standard ISO / IEC 20003-1: 2007 is defined as Table 9.

In addition, bsNumInCh, which is the number of channels of the downmix signal in the N-N / 2-N structure, may be implemented as shown in Table 10 below.

In this case, NumInCh refers to the number of channels of the downmix signal input to the decoding apparatus of the NN / 2-N structure, and NumOutCh refers to the number of channels of the output signal to which the downmix signal is upmixed. In the NN / 2-N structure, N _{LFE which} is the number of LFE channels among the output signals may be implemented as shown in Table 11 below. NumLfe means the number of LFE channels (N _LFE ) in the NN / 2-N structure.

In the N-N / 2-N structure, the channel order of the output signal may be implemented as shown in Table 12 according to the number of channels of the output signal and the number of LFE channels.

In Table 7, bsHasSpeakerConfig is a flag indicating whether the layout of the output signal to be actually reproduced is different from the channel order specified in Table 12. If bsHasSpeakerConfig == 1, audioChannelLayout, which is the layout of the loudspeakers during actual playback, may be used for rendering.

And audioChannelLayout represents the layout of the loudspeaker Loudspeaker at the time of actual reproduction. If the output signal contains an LFE channel, the channel order of the LFE channel is determined by (i) a condition processed with a channel other than the LFE channel using an OTT box, and (ii) a condition located last in the channel list. Can be determined to satisfy. (E.g., L, Lv, R, Rv, Ls, Lss, Rs, Rss, C, LFE, Cvr, LFE2) For example, LFE channels are L, Lv, R, Rv, Ls, Lss It is located last in Rs, Rss, C, LFE, Cvr, and LFE2.

The N-N / 2-N structure shown in FIG. 8 may be represented in a tree form as shown in FIG. 9. In FIG. 9 all OTT boxes can regenerate two channels of output signals based on CLD, ICC, residual signal and input signal. OTT boxes and their corresponding CLD, ICC, residual and input signals may be numbered in the order in which they appear in the bitstream.

According to FIG. 9, there are N / 2 of the plurality of OTT boxes. In this case, the decoder, which is a multichannel signal processing apparatus, may generate N-channel output signals from N / 2-channel downmix signals using N / 2 OTT boxes. Here, N / 2 OTT boxes are not implemented through a plurality of layers. That is, the OTT boxes may perform upmixing in parallel for each channel of the downmix signal of the N / 2 channel. In other words, one OTT box is not connected to another OTT box.

The left tree structure of FIG. 9 shows an N-N / 2-N tree structure when no LFE channel is applied, and the right tree structure shows an N-N / 2-N tree structure when an LFE channel is applied. All OTT boxes shown in FIG. 9 may remix two channels of output signals by upmixing one channel of downmix signals (M).

In this case, when the LFE channel is not included in the output signal of the N channel, the N / 2 OTT boxes may generate the output signal of the N channel using the residual signal res and the downmix signal M. FIG. However, when the LFE channel is included in the output signal of the N channel, the OTT box in which the LFE channel is output among the N / 2 OTT boxes may use only the downmix signal except the residual signal.

In addition, when the LFE channel is included in the output signal of the N channel, the OTT box in which the LFE channel is not output among the N / 2 OTT boxes upmixes the downmix signal using CLD and ICC, but the LFE channel is The output OTT box can upmix the downmix signal using only the CLD.

If the LFE channel is included in the output signal of the N channel, the OTT box in which the LFE channel is not output among the N / 2 OTT boxes generates an uncorrelated signal through the decorrelator, but the OTT in which the LFE channel is output. The box does not perform uncorrelated processes and therefore does not generate uncorrelated signals.

According to an embodiment of the present invention, an N / 2 channel downmix signal may be generated from an N channel input signal through MPS encoding. The N-channel output signal may be generated from the downmix signal of the N / 2 channel through MPS decoding.

However, in the conventional MPS standard, the channels of the downmix signal output through the encoder are 1 channel, 2 channels, and 5.1 channels. However, the present invention is not limited thereto. However, additional syntax definition is required to support the number of channels of downmix signals that are not defined in the existing MPS standard.

In the MPS standard, input / output relationships can be defined through BsTreeConfig as shown in Table 9. BsTreeConfig defines the decoding process of input and output signals.

In the case of BsTreeConfig 0, a process of generating a downmix signal of one channel from an input signal of six channels (5.1 channels) and an output signal of six channels (5.1 channels) from a downmix signal of one channel is defined. To this end, the decoder needs five OTT boxes, and channel level difference (CLD) may be applied to each OTT box.

At this time, the CLD input to the OTT box may be defined up to defaultCLD [0 ~ 5] according to the position of the OTT box, and the CLD corresponding to the OTT box is enabled. That is, if CLD is enabled, CLD may be input to the OTT box. ottModeLfe also means that the LFE channel is output from the OTT box.

According to Table 9 defined in the current MPS standard, only defaultCLD [0 ~ 5] corresponding to six OTT boxes is defined. Thus, the current MPS standard does not cover the case where the channels of the input signal exceed 10 to produce more than 5 channels of downmix.

To this end, the present invention can process an input signal having a channel different from the channel defined in the existing MPS standard by using the reserved bit in the MPS standard. For example, when N, the channel number of the input signal, is 24, and the channel number of the downmix signal is 12, it may be defined as shown in Table 13.

10 shows a decoder implemented according to Table 13. Referring to FIG. 10, a process of generating an output signal of 24 channels including two LFE channels from a 12-channel downmix signal x _0- x ₁₁ is illustrated.

Referring to the vector x (1001) in FIG. 10, 12 channels of downmix signals (x0-x11) and 12 signals of residual signals (res ₁ -res ₁₁ ) are input, but will be described below except for the residual signal. do. The decoder of FIG. 10 may input a downmix signal of 12 channels to the decorrelator 1007 to generate an uncorrelated signal.

The vector v 1003 of FIG. 10 may be derived by applying the matrix M1 1002 to the vector x 1001. The vector v 1003 may be determined according to Equation 25 below.

(25) corresponds to (1). When the residual signal res does not exist in Equation 25, x _Mo to x _M11 may be mapped to v _M0 to v _M11 . The uncorrelated signal may be derived equal to the number of downmix signals.

The vector w 1004 may be determined according to Equation 26 below.

Equation 26 corresponds to Equation 2. The decorrelator 1007 operates when there is no residual signal. That is, if there is no residual signal, an uncorrelated signal may be generated. D () is used when the decorrelator generates an uncorrelated signal. In Equation 26, if a residual signal exists,

Is 0 otherwise 1. In other words,

When 1 is uncorrelated signal can be generated according to the equation (15).

In FIG. 10, the vector y 1006 may be derived by applying the matrix M2 1005 to the vector w 1004 according to Equation 27. Vector y 1006 corresponds to an output signal of N channels (N = 24).

The process of deriving the matrix M1 1002 and the matrix M2 1005 may be derived through the description of FIG. 8. R1 for deriving the matrix M1 1002 is represented by Equation 28 below, and R2 for deriving the mates M2 1005 is represented by Equation 29 below.

H _LL , H _LR , H _RL , and H _RR in Equation 29 may be derived from CLD and ICC corresponding to each OTT box.

The present invention proposes an OTT-based MPS (MPEG Surround) decoder having a parallel structure that generates N-channel output signals from N / 2 channel downmix signals according to newly defined bsTreeConfig information.

Referring to FIG. 11, each OTT box generates two channels of signals using a downmix signal of one channel and an uncorrelated signal generated through the decorrelator (D). In the OTT box, defaultCld [0] to defaultCld [9] corresponding to the CLD, and OttModelfe [0] and OttModelfe [1] corresponding to the LFE channel may be input. For example, when the output signal is 22.2 channels, the LFE channel may be included in the output signal. OttModelfe [0] and OttModelfe [1] are then enabled.

According to FIG. 12, a case in which 12 channels of downmix signals M _{0 to} M ₁₁ are input to each OTT box is illustrated. Then, the output signal y of 24 channels is generated. Here, CLD and ICC are also input to each OTT box. Although the residual signal is illustrated in FIG. 12 as being input to the OTT box, if there is no residual signal, an uncorrelated signal generated through the decorrelator from the downmix signal may be input to the OTT box instead of the residual signal.

Multi-channel audio signal processing method according to an embodiment of the present invention comprises the steps of identifying the downmix signal and the residual signal of the N / 2 channel generated from the input signal of the N channel; Applying a downmix signal and a residual signal of the N / 2 channel to a first matrix; Outputs a first signal input to the N / 2 decorrelators corresponding to N / 2 OTT boxes and a second signal transmitted to the second matrix without being input to the N / 2 decorrelators through the first matrix Making; Outputting uncorrelated signals from a first signal through the N / 2 decorrelators; Applying the uncorrelated signal and the second signal to a second matrix; And generating an output signal of the N channel through the second matrix.

When the LFE channel is not included in the output signal of the N channel, N / 2 decorrelators may correspond to the N / 2 OTT boxes.

If the number of decorrelators exceeds the reference value of the modulo operation, the index of the decorrelator may be repeatedly reused according to the reference value.

When the LFE channel is included in the output signal of the N channel, the decorrelator may use N / 2, except for the number of LFE channels, and the LFE channel may not use the decorrelator of the OTT box. .

When the temporal shaping tool is not used, the second matrix may be input with a vector including the second signal, the uncorrelated signal derived from the decorrelator, and the residual signal derived from the decorrelator. have.

When a temporal shaping tool is used, the second matrix is a spread comprising a vector corresponding to a direct signal consisting of the second signal and a residual signal derived from the decorrelator and an uncorrelated signal derived from the decorrelator. A vector corresponding to the signal may be input.

The generating of the N-channel output signal includes, when subband domain time processing (STP) is used, applying a scale factor based on a spread signal and a direct signal to a spread signal portion of the output signal to temporal envelope of the output signal. You can shape

The generating of the N-channel output signal may flatten and reshape the envelope of the direct signal portion for each channel of the N-channel output signal when guided envelope shaping (GES) is used.

The size of the first matrix may be determined according to the number of channels of the downmix signal applying the first matrix and the number of decorrelators, and the elements of the first matrix may be determined by the CLD parameter or the CPC parameter.

In accordance with another aspect of the present invention, there is provided a method of processing a multichannel audio signal, including: identifying a downmix signal of an N / 2 channel and a residual signal of the N / 2 channel; Inputting an N / 2 channel downmix signal and an N / 2 channel residual signal to the N / 2 OTT boxes to generate an N channel output signal, wherein the N / 2 OTT boxes are not connected to each other; The OTT box which is arranged in parallel without any other and outputs the LFE channel among the N / 2 OTT boxes receives (1) only the downmix signal except the residual signal, and (2) the CLD parameter among the CLD parameter and the ICC parameter. (3) Do not output uncorrelated signal through decorator.

An apparatus for processing a multichannel signal according to an embodiment of the present invention includes a processor for performing a multichannel signal processing method, and the multichannel signal processing method includes downmixing an N / 2 channel generated from an input signal of N channels. Identifying a signal and a residual signal; Applying a downmix signal and a residual signal of the N / 2 channel to a first matrix; Outputs a first signal input to the N / 2 decorrelators corresponding to N / 2 OTT boxes and a second signal transmitted to the second matrix without being input to the N / 2 decorrelators through the first matrix Making; Outputting uncorrelated signals from a first signal through the N / 2 decorrelators; Applying the uncorrelated signal and the second signal to a second matrix; And generating an output signal of the N channel through the second matrix.

In accordance with another aspect of the present invention, an apparatus for processing a multichannel signal includes a processor for performing a method for processing a multichannel signal, and the method for processing a multichannel signal includes: an N / 2 channel downmix signal and an N / 2 channel; Identifying a residual signal; Inputting an N / 2 channel downmix signal and an N / 2 channel residual signal to the N / 2 OTT boxes to generate an N channel output signal,

The N / 2 OTT boxes are arranged in parallel without being connected to each other, and an OTT box that outputs an LFE channel among the N / 2 OTT boxes receives (1) only a downmix signal except a residual signal, (2) It uses CLD parameter among CLD parameter and ICC parameter. (3) Does not output uncorrelated signal through decorator.

The apparatus described above may be implemented as a hardware component, a software component, and / or a combination of hardware components and software components. For example, the devices and components described in the embodiments may be, for example, processors, controllers, arithmetic logic units (ALUs), digital signal processors, microcomputers, field programmable arrays (FPAs), It may be implemented using one or more general purpose or special purpose computers, such as a programmable logic unit (PLU), microprocessor, or any other device capable of executing and responding to instructions. The processing device may execute an operating system (OS) and one or more software applications running on the operating system. The processing device may also access, store, manipulate, process, and generate data in response to the execution of the software. For convenience of explanation, one processing device may be described as being used, but one of ordinary skill in the art will appreciate that the processing device includes a plurality of processing elements and / or a plurality of types of processing elements. It can be seen that it may include. For example, the processing device may include a plurality of processors or one processor and one controller. In addition, other processing configurations are possible, such as parallel processors.

The software may include a computer program, code, instructions, or a combination of one or more of the above, and configure the processing device to operate as desired, or process it independently or collectively. You can command the device. Software and / or data may be any type of machine, component, physical device, virtual equipment, computer storage medium or device in order to be interpreted by or to provide instructions or data to the processing device. Or may be permanently or temporarily embodied in a signal wave to be transmitted. The software may be distributed over networked computer systems so that they may be stored or executed in a distributed manner. Software and data may be stored on one or more computer readable recording media.

The method according to the embodiment may be embodied in the form of program instructions that can be executed by various computer means and recorded in a computer readable medium. The computer readable medium may include program instructions, data files, data structures, etc. alone or in combination. The program instructions recorded on the media may be those specially designed and constructed for the purposes of the embodiments, or they may be of the kind well-known and available to those having skill in the computer software arts. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tape, optical media such as CD-ROMs, DVDs, and magnetic disks, such as floppy disks. Magneto-optical media, and hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. Examples of program instructions include not only machine code generated by a compiler, but also high-level language code that can be executed by a computer using an interpreter or the like. The hardware device described above may be configured to operate as one or more software boxes to perform the operations of the embodiments, and vice versa.

Although the embodiments have been described by the limited embodiments and the drawings as described above, various modifications and variations are possible to those skilled in the art from the above description. For example, the described techniques may be performed in a different order than the described method, and / or components of the described systems, structures, devices, circuits, etc. may be combined or combined in a different form than the described method, or other components. Or even if replaced or substituted by equivalents, an appropriate result can be achieved. Therefore, other implementations, other embodiments, and equivalents to the claims are within the scope of the claims that follow.

Claims

Identifying a downmix signal of the N / 2 channel derived from the input signal of the N channel;

Generating an N-channel output signal from the identified N / 2 channel downmix signal using a plurality of OTT boxes

Including,

And the number of the plurality of OTT boxes is equal to N / 2 which is the number of channels of the downmix signal when there is no LFE channel in the output signal.
The method of claim 1,

Each of the plurality of OTT boxes,

The multi-channel signal processing method of generating a two-channel output signal using a non-correlation signal and a one-channel downmix signal generated from a decorrelator corresponding to each of the plurality of OTT boxes.
The method of claim 2,

When N, the channel number of the output signal, exceeds the preset channel number M,

The decorrelator includes a first decorrelator corresponding to a channel less than or equal to M and a second decorrelator corresponding to a channel greater than or equal to M,

And the second decorrelator reuses a filter set of the first decorrelator.
The method of claim 2,

The OTT box of which the output is an LFE channel among the plurality of OTT boxes generates a two-channel downmix signal without using an uncorrelated signal.
The method of claim 2,

Each of the plurality of OTT boxes,

The multi-channel signal processing method for generating a two-channel output signal using the residual signal and the one-channel downmix signal in place of the uncorrelated signal, if there is a transmitted residual signal.
The method of claim 1,

Generating the output signal of the N channel,

A multi-channel signal processing method for generating an N-channel output signal using a pre decorrelator matrix M1 and a mix matrix M2.
The method of claim 1,

Each of the plurality of OTT boxes, the multi-channel signal processing method for generating an output signal of the N channel using a channel level difference (CLD).
The method of claim 1,

The channel number N of the output signal is an even number from 10 to 32 multi-channel signal processing method.
Decoding the downmix signal of the N / 2 channel encoded according to the first coding scheme; And

Generating an output signal of the N channel from the downmix signal of the N / 2 channel according to a second coding scheme

Including,

The second coding scheme is

When the output signal does not include an LFE channel, the multi-channel signal processing method using the same number of one-to-two (OTT) boxes equal to N / 2 which is the number of channels of the downmix signal.
In the multi-channel signal processing apparatus,

A process for executing a multi-channel signal processing method,

The process is

Identify the downmix signal of the N / 2 channel derived from the input signal of the N channel,

Generating an N-channel output signal from the identified N / 2 channel downmix signal using a plurality of OTT boxes,

And the number of the plurality of OTT boxes is equal to N / 2 which is the number of channels of the downmix signal when there is no LFE channel in the output signal.
The method of claim 10,

Each of the plurality of OTT boxes,

And a two-channel output signal using a non-correlation signal generated from a decorrelator corresponding to each of the plurality of OTT boxes and a downmix signal of one channel.
The method of claim 11,

When N, the channel number of the output signal, exceeds the preset channel number M,

The decorrelator includes a first decorrelator corresponding to a channel less than or equal to M and a second decorrelator corresponding to a channel greater than or equal to M,

And the second decorrelator reuses a filter set of the first decorrelator.
The method of claim 11,

An OTT box whose output is an LFE channel among the plurality of OTT boxes generates a downmix signal of two channels without using an uncorrelated signal.
The method of claim 11,

Each of the plurality of OTT boxes,

The multi-channel signal processing apparatus for generating a two-channel output signal using the residual signal and the one-channel downmix signal in place of the uncorrelated signal, if there is a transmitted residual signal.
The method of claim 10,

The process is

A multi-channel signal processing apparatus for generating an output signal of the N channel by using a pre decorrelator matrix M1 and a mix matrix M2.
The method of claim 10,

Each of the plurality of OTT boxes, the multi-channel signal processing device for generating an output signal of the N channel using a channel level difference (CLD).
The method of claim 10,

And a channel number N of the output signal is an even number ranging from 10 to 32.
In the multi-channel signal processing apparatus,

A process for executing a multi-channel signal processing method,

The process is

Decode the downmix signal of the N / 2 channel encoded according to the first coding scheme,

Generating an output signal of the N channel from the downmix signal of the N / 2 channel according to a second coding scheme,

The second coding scheme is

When the output signal does not include an LFE channel, the multi-channel signal processing apparatus using the same number of one-to-two (OTT) boxes equal to N / 2 which is the number of channels of the downmix signal.