MX2008009565A

MX2008009565A - Apparatus and method for encoding/decoding signal

Info

Publication number: MX2008009565A
Application number: MX/A/2008/009565A
Authority: MX
Inventors: Suk Pang Hee; Hyun Lim Jae; Won Jung Yang; Soon Kim Dong; O Oh Hyun
Original assignee: Won Jung Yang; Kim Dong Soo; Lg Electronics Inc; Hyun Lim Jae; O Oh Hyun; Suk Pang Hee
Priority date: 2006-02-07
Filing date: 2008-07-25
Publication date: 2008-10-03

Abstract

An encoding method and apparatus and a decoding method and apparatus are provided. The decoding method includes extracting a three-dimensional (3D) down-mix signal and spatial information from an input bitstream, removing 3D effects from the 3D down-mix signal by performing a 3D rendering operation on the 3D down-mix signal, and generating a multi-channel signal using the spatial information and a down-mix signal obtained by the removal. Accordingly, it is possible to efficiently encode multi-channel signals with 3D effects and to adaptively restore and reproduce audio signals with optimum sound quality according to the characteristics of a reproduction environment.

Description

DEVICE AND METHOD OF CODING / DECODING OF A SIGNAL TECHNICAL FIELD The present invention relates to a coding / decoding method and to an encoding / decoding apparatus, and more particularly to an encoding / decoding apparatus that can process an audio signal of such that three-dimensional (3D) sound effects and an encoding / decoding method using the encoding / decoding apparatus can be created. BACKGROUND OF THE PRACTICE The coding apparatus subjects a multi-channel signal to a reductive mix in a signal with fewer channels, and transmits the signal subjected to reductive mixing to a decoding apparatus. Then, the decoding apparatus restores a multichannel signal from the signal subjected to reductive mixing and reproduces the multichannel signal restored using three or more speakers, for example 5 speakers of a channel. Multichannel signals can be reproduced by 2-channel speakers such as headphones. In this case, for a user to feel as if the sounds produced by the 2-channel speakers were reproduced from three or more sound sources, it is necessary to develop three-dimensional (3D) processing techniques capable of coding or decode multichannel signals in such a way that 3D effects can be created. DISCLOSURE OF THE INVENTION TECHNICAL PROBLEM The present invention provides an encoding / decoding apparatus and an encoding / decoding method that can reproduce multichannel signals in various reproduction environments by efficiently processing signals with 3D effects. TECHNICAL SOLUTION In accordance with one aspect of the present invention, a decoding method is provided for restoring a multi-channel signal, the decoding method includes extracting a three-dimensional (3D) signal subjected to reductive mixing and spatial information from a bit stream input, remove the 3D effects of the 3D signal subjected to reductive mixing to perform a 3D presentation operation on the 3D signal subjected to reductive mixing, and generate a multi-channel signal using spatial information and a signal subjected to reductive mixing obtained by the removal. In accordance with another aspect of the present invention, there is provided a decoding method for restoring a multi-channel signal, the decoding method includes extracting a 3D signal subjected to reductive mixing and spatial information from an input bit stream, generate a multichannel signal using the 3D signal subjected to reductive mixing and spatial information, and remove the 3D effects of the multichannel signal by performing a 3D presentation operation on the multichannel signal. In accordance with another aspect of the present invention, there is provided a coding method for encoding a multi-channel signal with several channels, the coding method includes encoding the multichannel signal in a signal subjected to reductive mixing with fewer channels, generating spatial information on the several channels, generating a 3D signal subjected to reductive mixing by performing a 3D presentation operation on the signal subjected to reductive mixing, and generating a bitstream including the 3D signal subjected to reductive mixing and spatial information. In accordance with another aspect of the present invention, there is provided a coding method for encoding a multi-channel signal with several channels, the coding method includes performing a 3D presentation operation on the multichannel signal, the coding of a multichannel signal obtained by the 3D display operation in the 3D signal subjected to reductive mixing with fewer channels, generate spatial information on the plurality of channels, and generate a current that includes the 3D signal subjected to reductive mixing and information spatial In accordance with another aspect of the present invention, a decoding apparatus is provided for restoring a multi-channel signal, the decoding apparatus includes a bit unpacking unit that extracts a coded 3D signal subjected to reductive mixing and spatial information from an input bit stream, a mixing decoder Reductive decoding the 3D encoded signal subjected to reductive mixing, a 3D generation unit that removes the 3D effects of the decoded 3D signal subjected to reductive mixing obtained by the decoding performed by the reductive mixing decoder by performing a presentation operation 3D in the decoded signal subjected to reductive mixing and a multichannel decoder that generates a multichannel signal using spatial information and a signal subjected to reductive mixing obtained by the removal made by the 3D generation unit. In accordance with another aspect of the present invention, there is provided a decoding apparatus for restoring a multichannel signal, the decoding apparatus includes a bit unpacking unit that extracts a coded 3D signal subjected to reductive mixing and spatial information from a stream of input bits, a reductive mixing decoder that decodes the encoded 3D signalsubjected to reductive mixing, a multichannel decoder that generates a multichannel signal using the spatial information and the 3D signal subjected to reductive mixing obtained by the decoding performed by the reductive mixing decoder, and a 3D generation unit that removes the 3D effects of the multichannel signal by performing a 3D presentation operation on the multichannel signal. In accordance with another aspect of the present invention, there is provided an encoding apparatus for encoding a multi-channel signal with a plurality of channels, the coding apparatus includes a multi-channel encoder that encodes the multichannel signal in a signal subjected to reductive mixing with fewer channels and generates spatial information about the plurality of channels, a 3D generating unit that generates a 3D signal subjected to reductive mixing by performing a 3D presentation operation on the signal subjected to reductive mixing, a reductive mixing encoder that encodes the 3D signal subjected to reductive mixture; and a packet of bits that generates a bitstream including the encoded 3D signal subjected to reductive mixing and spatial information. In accordance with another aspect of the present invention, there is provided an encoding apparatus for encoding a multichannel signal with a plurality of channels, the encoding apparatus includes a 3D presentation unit which performs a 3D presentation operation on the multichannel signal, a multi-channel encoder that encodes a multichannel signal obtained in the 3D presentation operation in a 3D signal subjected to reductive mixing with fewer channels and generates a spatial information on the beach of the channels, a reductive mixing encoder that encodes the 3D signal subjected to reductive mixing, and a bit packet formation unit that generates a bitstream including the 3D signal subjected to encoded reductive mixing and spatial information. In accordance with another aspect of the present invention, there is provided a bit stream that includes a data field that includes information about a 3D signal subjected to reductive mixing, a filter information field including filter information identifying a used filter for the generation of the promised 3D signal to the reductive mixture, a first header field including information indicating whether the filter information field includes the filter information, a second header field including information indicating whether the information field filter includes filter coefficients or coefficients of an inverse filter of the filter, and a spatial information field that includes spatial information on a plurality of channels. In accordance with another aspect of the present invention, provides a computer readable recording medium having a computer program to execute any of the decoding methods described above and the coding methods described above. EFFECTIVE EFFECTS In accordance with the present invention, it is possible to efficiently encode multichannel signals with 3D effects and adaptively restore and reproduce audio signals with an optimum sound quality in accordance with the characteristics of a reproduction environment. BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a block diagram of an encoding / decoding apparatus in accordance with one embodiment of the present invention; FIGURE 2 is a block diagram of a coding apparatus in accordance with an embodiment of the present invention; FIGURE 3 is a block diagram of a decoding apparatus in accordance with one embodiment of the present invention; FIGURE 4 is a block diagram of a coding apparatus in accordance with another embodiment of the present invention; FIGURE 5 is a block diagram of a decoding apparatus according to another embodiment of the invention. present invention; FIGURE 6 is a block diagram of a decoding apparatus in accordance with another embodiment of the present invention; FIGURE 7 is a block diagram of a three-dimensional (3D) display apparatus in accordance with one embodiment of the present invention; FIGURES 8 to 11 illustrate bit streams in accordance with embodiments of the present invention; FIGURE 12 is a block diagram of an encoding / decoding apparatus for processing a signal subjected to arbitrary reductive mixing in accordance with an embodiment of the present invention; FIGURE 13 is a block diagram of an arbitrary signal compensation unit subjected to 3D reduction / display mixture in accordance with one embodiment of the present invention; FIGURE 14 is a block diagram of a decoding apparatus for processing a signal subject to compatible reductive mixing in accordance with an embodiment of the following invention; FIGURE 15 is a block diagram of a 3D reduction / rendering compatibility processing unit in accordance with one embodiment of the present invention; FIGURE 16 is a block diagram of a decoding apparatus for canceling the interference in accordance with one embodiment of the present invention. PREFERRED MODE OF THE INVENTION The present invention will now be described more fully with reference to the accompanying drawings in which exemplary embodiments of the present invention are shown. FIGURE 1 is a block diagram of an encoding / decoding apparatus in accordance with one embodiment of the present invention. With reference to FIGURE 1, a coding unit 100 includes a multi-channel encoder 110, a three-dimensional display unit (3D) 120, a reducing mixing encoder 130, and a packet formation unit of bits 140. The multi-channel encoder 110 submits a multichannel signal to a reductive mixture with a plurality of channels in a signal subjected to reductive mixing, such as for example a stereo signal or a mono signal and generates spatial information regarding the channels of the multichannel signal. Spatial information is necessary to restore a multichannel signal from a signal subjected to reductive mixing. Examples of spatial information include a channel level difference (CLD), which indicates the difference between the energy levels of a pair of channels, a coefficient of channel prediction (CPC), which is a prediction coefficient used to generate a three-channel signal based on a two-channel signal, a correlation between ICC channels), which indicates the correlation between a pair of channels, and a difference in channel time (CTD), which is the time interval between a pair of channels. The 3D display unit 120 generates a 3D signal subjected to reductive mixing based on the signal subjected to reductive mixing. The 3D signal subjected to reductive mixing can be a two-channel signal with three or more directivities and can therefore be reproduced by two-channel speakers such as 3D-effect headphones. In other words, the 3D signal subjected to reductive mixing can be reproduced by two-channel speakers in such a way that a user can feel as if the 3D signal subjected to reductive mixing was reproduced from a sound source with three or more channels. The direction of a sound source can be determined based on at least one of the difference between the intensities of two sounds respectively entered in both ears, the time interval between the two sounds and the difference between the phases of the two sounds. Accordingly, the 3D display unit 120 can convert the signal subjected to reductive mixing into a 3D signal subjected to reductive mixing based on the way humans can determine the 3D location of a sound source with a sense of hearing. The 3D presentation unit 120 can generate the 3D signal subjected to reductive mixing by filtering the signal subjected to reductive mixing using a filter. In this case the information related to the filter. For example, a filter coefficient, can be entered into the 3D presentation unit 120 by an external source. The display unit 3D 120 can use the spatial information provided by the multichannel encoder 110 to generate the 3D signal subjected to reductive mixing based on the signal subjected to reductive mixing. More specifically, the 3D display unit 120 can convert the signal subjected to reductive mixing into the 3D signal subjected to reductive mixing by converting it by the signal subjected to reductive mixing into an imaginary multichannel signal using the spatial information and filtering the imaginary multi-channel signal . The 3D display unit 120 can generate the 3D signal subjected to reductive mixing by filtering the signal subjected to reductive mixing using a header related transfer function filter (HRTF). An HRTF is a transfer function that describes the transmission of sound waves between a sound source in an arbitrary location and the eardrum, and returns a value that It varies according to the direction and height of a sound source. If a signal without directivity is filtered using the HRTF, the signal can be heard as if it were reproduced from a certain direction. The display unit 3D 120 can perform a 3D display operation in a frequency domain, for example, a discrete Fourier transformation domain (DFT) or a fast Fourier transformation domain (FFT). In this case, the 3D display unit 120 can perform DFT or FFT before the 3D display operation or it can perform reverse DFT (IDFT) or reverse FFT (IFFT) after the 3D presentation operation. The display unit 3D 120 can perform the 3D display operation in a quadrature mirror (QMF) / hybrid filter domain. In this case, the 3D presentation unit can perform QMF / hybrid analysis and synthesis operations before or after the 3D presentation operation. The display unit 3D 120 can perform the 3D presentation operation in a time domain. The display unit 3D 120 can determine in which domain the 3D display should be made according to the sound quality that is required and the operational capability of the coding / decoding apparatus. The reducing mixing encoder 130 encodes the output of signal subjected to reductive mixing by multichannel encoder 110 or signal output three subjected to reductive mixing by 3D display unit 120. Reductive mixing encoder 130 can encode the signal output subjected to reductive mixing by multichannel encoder 110 or the 3D signal output subjected to reductive mixing by the 3D presentation unit 120 using an audio coding method such as an advanced audio coding method (AAC), an MPEG (MP3) layer method, or a method of arithmetic coding with bits sections (BSAC). The reducing mixing encoder 130 may encode a signal subjected to a non-3D reductive mixture or a signal subjected to a 3D reductive mixture. In this case, the signal subjected to the non-3D coded reduction mixture and the signal subjected to the coded 3D reduction mixture can be included in a bitstream to be transmitted. The bit packet formation unit 140 generates a bit stream based on the spatial information and either the signal subjected to the encoded non-3D reduction mix or the signal subjected to the encoded 3D reduction mix. The bitstream generated by the bit packet formation unit 140 may include spatial information, reductive mixing identification information indicating whether a signal subjected to reductive mixing included in the bitstream is a signal subjected to non-3D reductive mixing or a signal subjected to 3D reductive mixing, and information identifying a filter used by the 3D presentation unit | (eg, HRTF coefficient information). In other words, the bitstream generated by the bit packet formation unit 140 can include at least one of a signal subjected to non-3D reductive mixing that has not yet been 3D processed and a signal subjected to a coded 3D reductive mixture that it is obtained through a 3D processing operation performed by an encoding apparatus, and identification information subjected to reductive mixing that identifies the type of signal subjected to reductive mixing included in the bit stream. It can be determined which of the signal subjected to non-3D reductive mixing and the signal subjected to the encoded 3D reductive mixture should be included in the bit stream generated by the bit packet formation unit 140 at the user's choice or according to the capabilities of the coding / decoding apparatus illustrated in FIGURE 1 and the characteristics of a reproduction environment. The HRTF coefficient information may include coefficients of an inverse function of an HRTF used by the 3D presentation unit 120. The HRTF coefficient information may include only a brief coefficient information of the HRTF used by the display unit 3D 120, for example, envelope information of the HRTF coefficients. If a bitstream including the coefficients of the inverse function of the HRTF is transmitted to a decoding apparatus, the decoding apparatus does not need to perform a coefficient conversion operation HRTF and consequently the amount of computing of the apparatus can be reduced. decoding The bitstream generated by the bit packet formation unit 140 can also include information about a variation of energy in the signal caused by filtering based on HRTF, ie, information about the difference between the energy of a signal to be filtered and the energy of a signal that has been filtered or the ratio between the energy of the signal to be filtered and the energy of the signal that has been filtered. A bit stream generated by the bit packet unit 140 may also include information indicating whether or not it includes HRTF coefficients. If HRTF coefficients are included in the bitstream generated by the bit packet unit 140, the bit stream may also information indicating whether or not it includes any of the HRTF coefficients used by the 3D display unit 120 or the coefficients of the inverse function HRTF. With reference to FIGURE 1, a first unit of decoding 200 includes a bit unpacking unit 210, a reductive mixing decoder 220, a 3D presentation unit 230, and a multi-channel decoder 240. The bit unpacking unit 210 receives an input bitstream from the unit 100 coding and extracts a coded signal subjected to reductive mixing and spatial information from the input bit stream. The reductive mixing decoder 220 decodes the coded signal subjected to reductive mixing. The reducing mixer decoder 220 can decode the signal subjected to encoded reduction mixing using an audio signal decoding method, for example an AAC method, an MP3 method, or a BSAC method. In accordance with what has been described above, the signal subjected to the encoded reduction mixture extracted from the input bit stream may be a signal subjected to a non-3D coded reduction mix or a signal subjected to a coded 3D reduction mix. The information indicating whether the signal subjected to the coded reduction mixture extracted from the input bit stream is a signal subjected to a non-3D coded reduction mix or a signal subjected to a coded 3D reduction mixture can be included in the bitstream entry . If the signal subjected to 3D coded reduction mix extracted from the input bit stream is a signal subject to 3D encoded reductive mixture, the signal subjected to the encoded reductive mixture may be possible to be reproduced after its decoding by the reductive mixer decoder 220. On the other hand, if the signal subjected to codered reductive mixtures extracted from the bit stream of input is a signal subjected to non-3D reductive mixing, the signal subjected to reductive mixing can be decoded by the reductive mixing decoder 220, and a signal subjected to reductive mixing obtained by decoding can be converted into a signal subjected to reductive mixing 3D decoded by a 3D display operation performed by the third display unit 233. The decoded 3D decoder signal can be easily reproduced. The presentation unit 3D 230 includes a first presenter 231, a second presenter 232 and a third presenter 233. The first presenter 231 generates a signal subjected to reductive mixing by performing a 3D presentation operation on a signal subjected to 3D reductive mixing. encoded by the reducing mixer decoder 220. For example, the first presenter 231 can generate a signal subjected to non-3D reductive mixing by removing the 3D effects of the signal subjected to the encoded 3D reduction mix. The 3D effects of the signal subject to 3D coded reduction mix can not be completely removed by the first presenter 231. In this case, a signal output subjected to reductive mixing by the first presenter 231 may have certain 3D effects. The first presenter 231 can convert the signal subjected to the 3D reductive mixture provided by the reductive mixing decoder 220 into a signal subjected to reductive mixing with 3D effects removed therefrom using a reverse filter of the filter used by the 3D presentation unit 120 of the coding unit 100. Information about the filter used by the display unit 3D 120 or the reverse filter of the filter used by the display unit 3D 120 may be included in the input bit stream. The filter used by the display unit 3D 120 can be a HRTF filter. In this case, the HRTF coefficients used by the coding unit 100 or the coefficients of the inverse function of the HRTF may also be included in the input bit stream. If the HRTF coefficients used by the coding unit 100 are included in the input bitstream, the HRTF coefficients can be inversely converted and the results of the inverse conversion can be used during the 3D rendering operation performed by the first presenter 231 If the coefficients of the inverse function of HRTF that is used by the coding unit 100 are included in the input bit stream, can be easily used during the 3D display operation performed by the first presenter 231 without being subject to any reverse conversion operation. In this case, the computation operation of the first decoding apparatus 100 can be shown. The input bitstream may also include a filter information per (eg, information indicating whether or not the HRTF coefficients used by the coding unit 100 are included in the input bitstream) and information indicating whether the filter has been inversely converted. The multi-channel decoder 240 generates a multi-channel 3D signal with three or more channels based on the signal subjected to reductive mixing with 3D effects removed therefrom and the spatial information extracted from the input bit stream. The second presenter 232 can generate a signal subjected to 3D reductive mixing with 3D effects by performing a .3D presentation operation on the signal committed to reductive mixing with 3D effects removed therefrom. In other words, the first presenter 231 removes the 3D effects of the signal submitted to the 3D coded reduction mixture provided by the reducing mixer decoder 220. Then, the second presenter 232 can generate a signal submitted to 3D reduction mixture combined with desired 3D effects by the first decoder apparatus 200 by performing a 3D display operation on the signal subjected to reductive mixing obtained by the removal performed by the first presenter 231, using a filter of the first decoding apparatus 200. The first decoding apparatus 200 may include a presenter in which two or more of the first presenter 231 ,, second presenter 232 and third presenter 233 which perform the same operations are integrated. A bit stream generated by the coding unit 100 can be input to a second decoding apparatus 300 having a different structure from the first decoding apparatus 200. The second decoding apparatus 300 can generate a signal subjected to 3D reduction mixing based on a signal subjected to a reductive mixture included in the input bit stream. More specifically, the second decoding apparatus 300 includes a bit unpacking unit 310, a reductive mixing decoder 320 and a 3D display unit 330. The bit unpacking unit 310 receives an input bitstream from the coding unit 100 and extracts a signal subjected to coded reduction mix and spatial information from the input bit stream. The mixing decoder Reductive 320 decodes the signal subjected to coded reductive mixing. The display unit 3D 330 performs a 3D display operation on the signal subjected to decoded reductive mixing in such a way that the signal subjected to decoded reductive mixing can be converted into a signal subjected to 3D reductive mixing. FIGURE 2 is a block diagram of a decoding apparatus in accordance with one embodiment of the present invention. With reference to FIGURE 2, the coding apparatus includes presentation units 400 and 420 and a multi-channel encoder 410. Detailed descriptions of the same coding processes as the coding processes of FIGURE 1 mode will be omitted. With reference to FIG. FIGURE 2, the 3D display units 400 and 420 can respectively be placed front and rear of the multichannel encoder 410. Accordingly, a multichannel auxiliary can be presented 3D through the 3D display unit 400 and then the multichannel signal presented 3D can to be coded by the multi-channel encoder 410, thereby generating a signal subjected to pre-processed, coded 3D reduction mix. Alternatively, the multichannel signal can be subjected to reductive mixing by the multichannel encoder 410 and then the signal subjected to reductive mixing can be presented 3D yet of 3D display 120 thereby generating a signal subjected to a coded, processed reducing mixture. Information indicating whether or not the multi-channel signal has been presented 3D before or after the reductive mixture can be included in a stream of bits to be transmitted. The presentation units 3D 400 and 420 can be placed both in front of or behind the multi-channel encoder 410. FIGURE 3 is a block diagram of a decoding apparatus in accordance with a present invention. With reference to FIGURE 3, the decoding apparatus includes 3D display units 430 and 450 and a multi-channel decoder 440. Detailed descriptions of the same decoding processes that the processes of the embodiment of FIGURE 1 were omitted. With reference to FIGURE 3, the 3D display units 430 and 450 may respectively be placed in front of and behind the multichannel decoder 440. The 3D display unit 430 may remove 3D effects from a signal submitted to a coded 3D reduction mix and enter a signal subjected to the reductive mixture obtained by the multi-channel decoding removal 430. Then, the multichannel decoder 430 can decode the signal subjected to reductive mixing and entered there, however a pre-processed multi-channel 3D signal. Alternatively, the multi-channel decoder 430 can restore a signal multichannel from the signal submitted to the 3D encoded reduction mix, and the 3D display unit 450 can remove the 3D effects of the restored multi-channel signal thereby generating a post-processed 3D multichannel signal. If a signal is submitted, the encoded 3D reduction mixture provided by an encoding apparatus has been generated by performing a 3D presentation operation and then an operation of. Reductive mixture, the signal subjected to 3D encoded reductive mixing can be decoded by performing a multi-channel decoding operation and then a 3D presentation operation. On the other hand, if the signal subjected to the encoded 3D reduction mixture has been generated during the performance of a reductive mixing operation and then a 3D presentation operation, the signal subjected to the 3D code reduction mix can be decoded by carrying out an operation 3D presentation and then a multi-channel decoding operation. Information indicating whether or not a signal subjected to 3D coded reduction mix has been obtained by performing a 3D rendering operation before or after a reductive mixing operation can be extracted from a bit stream transmitted by a coding apparatus. The presentation units 3D 430 and 450 can be placed both in front of or behind the multichannel decoder 440. FIGURE 4 is a block diagram of a coding apparatus in accordance with another embodiment of the present invention. With reference to FIGURE 4, the coding apparatus includes a multi-channel encoder 500, a 3D presentation unit 510, a reductive mixing encoder 520, and a bit packing unit 530. Detailed descriptions of the same coding processes as the Coding processes of the modality of FIGURE 1 will be omitted. With reference to FIGURE 4, the multichannel encoder 500 generates a signal subjected to reductive mixing and spatial information based on a multi-channel input signal. The presentation unit 3D 510 generates a signal subjected to 3D reduction mixing by performing a 3D presentation operation on the signal subjected to reductive mixing. It can be determined whether or not to perform a 3D presentation operation on the signal subject to reductive mixing at the choice of a user or in accordance with the capabilities of the coding apparatus, the characteristics of a reproduction environment, or the sound quality required . The reducing mix encoder 520 encodes the signal subjected to reductive mixing generated by the encoder multichannel 500 or the signal made to the 3D reduction mixture generated by the display unit 3D 510. The bit packer 530 generates a bit stream based on the spatial information or the signal subjected to a coded reduction mix or a signal submitted to 3D coded reduction mix. The bitstream generated by the bit packet unit 530 could include a reductive mix identifier information that indicates whether or not a signal subjected to the coded reductive mixture included in the bit stream is a signal subjected to non-3D reductive mixing without 3D effects or a signal submitted to 3D reduction mix encoded with 3D effects. More specifically, the reductive mixing identification information may indicate whether or not the bitstream generated by the bit packet unit 530 includes a signal subjected to non-3D reductive mixing, a signal subjected to a coded 3D reductive mixture, or both. FIGURE 5 is a block diagram of a decoding apparatus in accordance with another embodiment of the present invention. With reference to FIGURE 5, the decoding apparatus includes a bit packing unit 540, a mix decoder 550, and a 3D presentation unit 560. Detailed descriptions of the same decoding processes as the mode decoding processes of FIGURE 1 will be omitted.

With reference to FIGURE 5, the unpacking unit of bits 540 extracts a signal subjected to coded reduction mixing, spatial information, as well as reductive mixing identification information of an input bit stream. The reductive mixing identification information indicates whether or not the signal subjected to the encoded reductive mixture is a signal subjected to non-3D reductive mixing encoded without 3D effects or a signal subjected to 3D reductive mixing encoded with 3D effects. If the input bitstream includes both a signal subjected to non-3D reductive mixing and a signal subjected to reductive 3D mixing, only one of the signal subjected to non-3D reductive mixing and the signal subjected to the reductive 3D mixture can be extracted from the reductive current. input bits of a user's choice or in accordance with the capabilities of the decoding apparatus, the characteristics of a reproduction environment or the required sound quality. The reducing mixer decoder 550 decodes the signal subjected to the coded reduction mix. If the signal subjected to the reductive mixture obtained by the decoding made by the reductive mixing decoder 550 is a signal subjected to a 3D encoded reductive mixture obtained by performing a 3D presentation operation, the signal subjected to reductive mixing can be easily reproduced. On the other hand, if the signal subjected to reductive mixing obtained by the decoding performed by the reductive mixing decoder 550 is a signal subjected to reductive mixing without 3D effects, the 3D presentation unit 560 can generate a signal subjected to decoded 3D reductive mixing by performing a 3D presentation operation in the signal submitted to the reductive mixture obtained by the decoding performed by the reductive mixing decoder 550. FIGURE 6 is a block diagram of a decoding apparatus according to another embodiment of the present invention. With reference to FIGURE 6, the decoding apparatus includes a bit unpacking unit 600, a reductive mixing decoder 610, a first display unit of 3D 620, a second display unit 3D 630, and a storage unit of filter information 640. Detailed descriptions of the same decoding processes that the decoding processes of the FIGURE 1 mode were omitted. The unpacking unit of bits 600 extracts a signal subjected to a coded 3D reduction mixture and a spatial information from an input bit stream. The reductive mixing decoder 610 decodes the signal subjected to encoded 3D reductive mixing. The first 3D display unit 620 removes the 3D effects of a signal submitted to a 3D encoded reduction mix obtained by the decoding performed by the mixing decoder 610, using a reverse filter of a filter of a coding apparatus used to perform a 3D display operation. The second display unit 630 generates a signal subjected to 3D reduction mixing combined with 3D effects by performing a 3D display operation on a signal subjected to reductive mixing obtained by the removal effected by the first display unit 3D 620, using a filter stored in the decoding device. The second 3D display unit 630 can perform a 3D display operation using a filter having different characteristics of the filter of the coding unit used to perform a 3D display operation. For example, the second display unit 3D 630 may perform a 3D display operation using an HRTF having coefficients different from the coefficients of a HRTF used by an encoding apparatus. The filter information storage unit 640 stores filter information on a filter used to make a 3D presentation, for example, HRTF coefficient information. The second 3D display unit 630 can generate a combined 3D reduction mix using the filter information stored in the unit of storage of filter information 640. The filter information storage unit 640 can store several filter information corresponding to several filters respectively. In this case, one of the various filter information may be selected at the choice of a user or according to the capabilities of the decoding apparatus or as required by the sound quality. People of different races may have different auditory structures. Therefore, optimized HRTF coefficients for different individuals may differ between them. The decoding apparatus illustrated in FIGURE 6 can generate a signal subject to 3D reduction mix optimized for the user. In addition, the decoding apparatus illustrated in FIGURE 6 can generate a signal subject to 3D reduction mixing with 3D effects corresponding to a HRTF filter desired by the user, regardless of the HRTF type provided by a signal provider subject to 3D reduction mixing. FIGURE 7 is a block diagram of a 3D display apparatus in accordance with one embodiment of the present invention. With reference to FIGURE 7, the 3D presentation apparatus includes a first domain conversion unit 700 and a second domain conversion unit 720 and a 3D presentation unit 710. To effect a 3D display operation in a predetermined domain, the first domain conversion unit 700 and the second domain conversion unit 720 may be placed, respectively, in front of and behind the display unit 3D 710. With reference to FIGURE 7, a signal subjected to reductive input mixing is converted into a signal subjected to frequency domain reductive mixing by the first domain conversion unit 700. More specifically, the first domain conversion unit 700 can convert the signal subjected to mixing Reductive input in a signal subjected to DFT domain reductive mixture or in a signal subjected to FFT domain reductive mixture by performing DFT or FFT. The 3D display unit 710 generates a multi-channel signal by applying spatial information to the signal subjected to the frequency domain reducing mixture provided by the first domain conversion unit 700. Next, the 3D display unit 710 generates a signal submitted to 3D reduction mix by filtering the multichannel signal. The . signal submitted to 3D reduction mix with the display unit 3D 710 is converted into a signal subjected to time domain 3D reduction mix by the second domain conversion unit 720. More specifically, the second domain conversion unit 720 can perform IDFT or IFFT on the signal subjected to 3D reduction mixture generated by the 3D presentation unit 710. During the conversion of a signal subjected to frequency domain 3D reduction mix into a signal subjected to mixing Reductive 3D time domain, a data loss or a data distortion, for example, overlap may occur. In order to generate a multichannel signal and a signal subjected to 3D reduction mixing in a frequency domain, the spatial information for each parameter band can be mapped in the frequency domain and several filter coefficients can be converted into the domain of frequency. The 3D display unit 710 can generate a signal subjected to 3D reduction mixing by multiplying the signal subjected to the frequency domain reducing mixture provided by the first domain conversion unit 700, the spatial information and the filter coefficients. A time domain signal obtained by multiplying a signal subjected to reductive mixing, spatial information and a plurality of filter coefficients all represented in a frequency domain of M points has M valid signals. In order to represent the signal subjected to reductive mixing, the spatial information and the filter in the frequency domain of M points, can be perform DTF of M points or FFT of M points. Valid signals are signals that do not necessarily have a value of 0. For example, a total of x valid signals can be generated by obtaining x signals from an audio signal through sampling. Between x valid signals, and valid signals can be filled with zeros. Then the number of valid signals is | reduced to (x-y). Subsequently, a signal with valid signals and a signal with b valid signals are subjected to convolution, thereby obtaining a total of (a + £ > -l) valid signals. The multiplication of the signal subjected to the reductive mixture, the spatial information and the filter coefficients in the frequency domain of M points can offer the same effect as the convolution of the signal subjected to the reductive mixture, the spatial information, and the coefficients of filter in a time domain. A signal with (3 * M-2) valid signals can be generated by converting the signal subjected to reductive mixing, spatial information and filter coefficients in the frequency domain of M points' to a time domain and submit to convolution the results of the conversion. Accordingly, the number of valid signals of a signal obtained by multiplying a signal subjected to reductive mixing, spatial information, and coefficients of filter in a frequency domain and the conversion of the multiplication result to a time domain may differ from the number of valid signals of a signal obtained by the convolution of the signal subjected to the reductive mixture, the spatial information and the filter coefficients in the time domain. As a result, overlapping may occur during the conversion of a signal subjected to 3D reductive mixing in a frequency domain into a time domain signal. In order to avoid overlapping, the sum of the number of valid signals of a signal subjected to reductive mixing in a time domain, the number of valid signals of spatial information mapped in a frequency domain, and the number of filter coefficients they must not be greater than M. The number of valid signals of spatial information mapped in a frequency domain can be determined through the number of points in the frequency domain. In other words, if the spatial information represented by each parameter band is mapped in a frequency domain of N points. With reference to FIGURE 7, the first domain conversion unit 700 includes a first zero padding unit 701 and a first frequency domain conversion unit 702. The third display unit 710 includes a mapping unit 711, a domain conversion unit of time 712, a second zero-fill unit 713, a second frequency-domain conversion unit 714, a multi-channel signal generation unit 715, a third zero-fill unit 716, a third frequency-domain unit 717 , and a signal generation unit subjected to 3D reduction mixture 718. The first zero filling unit 701 performs a zeroing operation in a signal subjected to reductive mixing with X samples in a time domain such that the number of samples of the signal subjected to reductive mixing can be implemented from X to M. The first frequency domain conversion unit 702 converts the signal subjected to reductive mixture filled with zeros into a frequency domain signal of M points. The signal subjected to reductive mixture filled with zeros has M samples. Among the M samples of the signal subjected to reductive mixture filled with zeros, only X samples are valid signals. The mapping unit 711 maps spatial information for each parameter band to a frequency domain of N points. The time domain conversion unit 712 converts the spatial information obtained by the mapping performed by the mapping unit 711 into a time domain. The spatial information obtained by the conversion made by the time domain conversion unit 712 has N samples The second zero-fill unit 713 performs a zero-fill operation on the spatial information with N samples in the time domain such that the number of spatial information samples can be increased from N to M. The second unit frequency domain conversion 714 converts spatial information filled with zeros into a frequency domain signal of N points. The spatial information filled with zeros has N samples. Among the N samples of spatial information filled with zeros, only N samples are valid. The multi-channel signal generation unit 715 generates a multichannel signal by multiplying the signal subjected to the reductive mixture provided by the first frequency domain conversion unit 712 and the spatial information provided by the second frequency domain conversion unit 714 The multi-channel signal generated by the multi-channel signal generation unit 715 has M valid signals. On the other hand, a multi-channel signal obtained by convolution, in the time domain, of the signal subjected to the reductive mixture provided by the first frequency domain conversion unit 712 and the spatial information provided by the second domain conversion unit of frequency 714 has (X + Nl) valid signals.

The third zero padding unit 716 can perform a padding operation with zeroes in filter coefficients Y plotted in the time domain such that the number of samples can be increased to M. The third frequency domain conversion unit 717 converts the filter coefficients filled with zeros in the frequency domain of M points. The filter coefficients filled with zeros have M samples. Among the M samples, only Y samples are valid signals. The signal generation unit subjected to 3D reduction mixtures 718 generates a signal subjected to 3D reductive mixing by multiplying the multichannel signal generated by the multi-channel signal generation unit 715 and a plurality of filter coefficients provided by the third unit. frequency domain conversion 717. The signal subjected to 3D reduction mixture generated by the signal generation unit subjected to 3D reduction mixture 718 has M valid signals. On the other hand, a signal subjected to 3D reduction mixture obtained by the convolution, in the time domain, of the multichannel signal generated by the multi-channel signal generation unit 715 and the filter coefficients provided by the third domain conversion unit frequency 717 has (X + N + Y-2) valid signals. It is possible to avoid overlapping by adjusting the domain of frequency M points used for the first frequency domain conversion unit 702, the second frequency domain conversion unit 714, and the third frequency domain conversion unit 717 to meet the following equation: = (X + N + Y-2). In other words, it is possible to avoid overlapping by enabling the first, second and third frequency domain conversion units 702, 714, and 717 to perform DFT of M points or FFT points that meet the following equation: M = (X + N + Y-2). The conversion to a frequency domain can be done using a filter bank other than a DFT filter bank, an FFT filter bank and a QMF bank. The generation of a signal subjected to a 3D reduction mixture can be carried out using a HRTF filter. The number of valid signals of spatial information can be adjusted using a method different from the methods mentioned above or it can be adjusted using one of the methods mentioned above that is more efficient and requires the least amount of computation. The overlap can occur not only during the conversion of a signal, a coefficient or spatial information from a frequency domain to a time domain or vice versa but also during the conversion of a signal, a coefficient or a spatial information from a QMF domain to a hybrid domain or vice versa. Methods mentioned above to avoid overlapping can also be used to avoid overlapping during the conversion of a signal, a coefficient or spatial information from a QMF domain to a hybrid domain or vice versa. The spatial information used to generate a multichannel signal or a signal subject to 3D reductive mixing may vary. As a result of the variation of spatial information, signal discontinuities can occur as noise in an output signal. The noise in the output signal can be reduced using a method of flattening through which spatial information can be prevented from changing rapidly. For example, when the first spatial information applied to a first frame differs from the second spatial information applied to a second frame when the first frame and the second frame are adjacent to each other, it is highly probable that a discontinuity occurs between the first frame and the second frame. second box. In this case, the second spatial information can be compensated using the first spatial information or the first spatial information can be compensated using the second spatial information in such a way that the difference between the first spatial information and the second spatial information can be reduced and that the noise caused by the discontinuity between the first frame and the second box can be reduced. More specifically, at least one of the first spatial information and second spatial information can be replaced with the mean of the first spatial information and the second spatial information, thereby reducing the noise. It is also likely that the noise is generated due to a discontinuity between a pair of bands of adjacent parameters. For example, when a third spatial information corresponding to a first parameter band differs from a fourth spatial information corresponding to a second parameter band when the first parameter band and the second parameter band are adjacent to each other, it is likely that a discontinuity occurs between the first band of parameter y. the second parameter band. In this case, the third spatial information can be compensated using the fourth spatial information or the fourth spatial information can be compensated using the third spatial information in such a way that the difference between the third spatial information and the fourth spatial information can be reduced and that the noise caused by the discontinuity between the first parameter band and the second parameter band may be reduced. More specifically, at least one of the third spatial information and fourth spatial information can be replaced with the mean of the third spatial information and fourth spatial information, thereby reducing the noise. The noise caused by a discontinuity between a pair of adjacent frames or a pair of adjacent parameter bands can be reduced using methods other than the methods mentioned above. More specifically, each frame can be multiplied by a window, for example, a Hanning window, and a "splice and add" scheme can be applied to the multiplication results in such a way that the variations between the frames can be reduced . Alternatively, an output signal to which various spatial information is applied can be smoothed in such a way that the presence of variations between several frames of the output signal can be avoided. The de-correlation between channels in a DFT domain that uses the spatial information, for example, ICC, can be adjusted in the following manner. The large decorrelation can be adjusted by multiplying a coefficient of a signal input to a one-to-two (OTT) or two-to-three (TTP) box by a predetermined value. The default value can be defined through the following equation: (A + (1-A * A) A0.5 * i) where A indicates an ICC value applied to a predetermined band of the OTT box or TTT e "i" indicates an imaginary part. The imaginary part can be positive or negative. The default value may accompany a weighting factor in accordance with the characteristics of the signal, for example, a signal energy level, the energy characteristics of each frequency of the signal or the type of box to which the value is applied. A of ICC. As a result of the introduction of the weighting factor, the degree of decorrelation can be further adjusted and a inter-frame flattening or interpolation can be applied.

In accordance with what has been described above, with reference to FIGURE 7, a signal subjected to 3D reductive mixing can be generated in a frequency domain by using a HRTF or a pulse response related to the header (HRIR), which is converted to the frequency domain. Alternatively, a signal subjected to 3D reductive mixing can be generated by convolving a HRIR and a signal subjected to reductive mixing in a time domain. A signal subjected to a 3D reduction mixture generated in a frequency domain can be left in the frequency domain without being subjected to reverse domain transformation. In order to subject a HRIR and a signal subjected to reductive mixing in a time domain to convolution, A finite filter response (FIR) or an infinite impulse response (IIR) can be used. In accordance with what is described above, a coding apparatus or a decoding apparatus in accordance with the embodiment of the present invention can generate a signal subjected to 3D reduction mixing using a first method that includes the use of a HRTF in a frequency line. or a HRIR converted to a frequency domain, a second method that includes the convolution of a HRIR in a time domain, or the combination of the first method and the second method. FIGURES 8 to 11 illustrate bit streams in accordance with embodiments of the present invention. With reference to FIGURE 8, a bitstream includes a multichannel decoding information field that includes the information necessary to generate a multi-channel signal, a 3D presentation information field that includes the information necessary for the generation of a signal submitted to 3D reducing mix, and a header field that includes the header information necessary for the use of the information included in the field of multichannel decoding information of the information included in the field of 3D presentation information. The bit stream may include only one or two of the multi-channel decoding information field, the field of the 3D presentation information, and the header field. With reference to FIGURE 9, a bit stream containing the information to be clarified necessary for a decoding operation may include a specific configuration header field that includes header information of a whole encoded signal and several frame data fields that they include collateral information on several tables. More specifically, each of the frame data fields may include a field of a frame header that includes header information of a corresponding frame and a frame parameter data field that includes spatial information of the corresponding frame. Alternatively, for one of the frame data fields it may include a frame parameter data field only. Each of the frame parameter data fields includes several modules, each module includes a flag and parameter data. The modules are a set of data that includes parameter data, for example, spatial information or other data, such as, for example, reductive mixing gain and flattening data that are necessary to improve the sound quality of a signal. If you receive information about module data specified by the box header fields without any flags additional, if the information specified by the box header fields are further classified, or if an additional flag and data are received in relation to the information not specified by the box header, the module data may not include any flags. Collateral information about a signal subjected to 3D reduction mixing, for example, HRTF coefficient information, may be included in at least one of the specific configuration header field, table header fields, and parameter data fields of frame.

With reference to FIGURE 10, a stream of bits may include a plurality of multichannel decoding information fields that include the information necessary for the generation of multichannel signals and a plurality of 3D presentation information fields that include the information necessary to generate signals subjected to 3D reduction mix. When the bitstream is received, a decoding apparatus may use either the multi-channel decoding information fields or the 3D presentation information field to perform a decoding operation and skip the multi-channel decoding information fields and fields of 3D presentation information that are not used in the decoding operation. In this case, you can determine which of the Multichannel decoding information fields and 3D presentation information fields must be used to perform a decoding operation in accordance with the type of signals to be reproduced. In other words, to generate multichannel signals, a decoding apparatus can skip the 3D presentation information fields and read the information included in the multichannel decoding information fields. On the other hand, in order to generate signals subject to 3D reduction mixing, a decoding apparatus may skip the multi-channel decoding information fields and read information included in the 3D presentation information fields. Below are methods for skipping some of the various fields in a stream of bits. First, a field length information that refers to the size in bits of a field may be included in a bit stream. In this case, the field can be skipped by jumping a number of bits that correspond to the bit size of the field. The field length information can be placed at the beginning of the field. Second, a synchronization word can be placed at the end or at the beginning of a field. In this case, the field can be skipped by locating the field based on the location of the synchronization word.

Third, if the length of a field is determined in advance and set, the field can be skipped by jumping a quantity of data corresponding to the length of the field. A fixed field length information on the field length may be included in a bit stream or it may be stored in a decoding apparatus. Fourth, one of several fields can be skipped using the combination of two or more of the field jump methods mentioned above. The field hop information which is information necessary to skip a field such as field length information, synchronization words, or fixed field length information may be included in one of the specific configuration header field, header fields of frame, and data fields of frame parameters illustrated in FIGURE 9 or may be included in a field different from the fields illustrated in FIGURE 9. For example, in order to generate multichannel signals, a decoding apparatus may jumping the 3D presentation information fields, with reference to the field length information, a synchronization word or fixed field length information placed at the beginning of each of the fields of 3D presentation information, and read information included in the multichannel decoding information fields. On the other hand, for the purpose of generating signals subject to 3D reduction mixing, a decoding apparatus may bypass the multichannel decoding information fields with reference to the field length information, a synchronization word, or field length information. fixed at the beginning of each of the multichannel decoding information fields, and read information included in the 3D presentation information fields. A bitstream may include information indicating whether or not data included in the bitstream is required to generate multichannel signals or to generate signals subject to 3D reduction mixing. However, even if a bitstream does not include any spatial information, such as CLD but only includes data (eg, HRTF filter coefficients) necessary to generate a signal subjected to 3D reductive mixing, a multi-channel signal can be reproduced at through decoding using the necessary data to generate a signal subjected to 3D reduction mixing without requiring spatial information. For example, a stereo parameter, which is spatial information on two channels, is obtained from a signal subjected to reductive mixing. After, the stereo parameter is converted into spatial information on several channels to be reproduced, and a multichannel signal is generated by the application of the spatial information obtained by the conversion to the signal subjected to reductive mixing. On the other hand, even if a bit stream includes only data necessary to generate a multichannel signal, a signal subjected to reductive mixing can be reproduced without requiring an additional decoding operation or a signal subjected to reductive mixing 3D can be reproduced by the made to perform 3D processing on the signal subjected to reductive mixing using an additional HRTF filter. If a bitstream includes both data necessary to generate a multichannel signal and data necessary to generate a multichannel signal and data necessary to generate a signal subjected to 3D reduction mixing, a user may decide whether or not to reproduce a multichannel signal or a signal submitted to 3D reduction mix. Methods for skipping data will be described below in greater detail with reference to the respective corresponding syntaxes. Syntax 1 indicates a method for decoding an audio signal in frame units. [Syntax 1] SpatialFrame () Framinglnfo (); bsIndependencyFlag; OttData () TttDataO SmgData () TempShapeData (); if (bsArbitraryDownmix). { ArbitaryDownmixData (); } if (bsResidualCoding). { ResidualData (); } } In Syntax 1, OttData () and TttDataO are modules that represent parameters (such as spatial information that includes a CLD, ICC, and CPC) needed to restore a multichannel signal from a signal subjected to reductive mixing, and SmgData ( ), TempShapeData (), ArbitraryDo nmixData (), and ResidualData () are modules that represent the information needed to improve sound quality by correcting for signal distortions that may have occurred during a coding operation. For example, if a parameter such as CLD, ICC or CPC and information included in the ArbitraryDownmixData () module are used only during a decoding operation, the SmgDataO and TempShapeData () modules, which are placed between the TttDataO and ArbitaryDownmixData () modules, may be unnecessary. Therefore, it is efficient to skip the SmgDataO and TempShapeData () modules. A method for skipping the modules in accordance with an embodiment of the present invention will now be described in detail with reference to Syntax 2 below. [Syntax 2] TttData (); SkipDataO. { t, | bsSkipBits; } SmgData (); TempShapeData (); if (bsArbitraryDownmxx). { ArbitraryDownmixData O; } With reference to Syntax 2, a SkipDataO module may be placed in front of a module to be skipped, and the size in bits of the module to be skipped is specified in the module SkipData () as bsSkipBits. In other words, considering the SmgData () and TempShapeData () modules to be skipped, and the size in bits of the combined SmgData () and TempShapeData () modules is 150, the SmgData () and TempShapeData ^) modules can be skipped setting bsSkipBits to 150. A method for skipping modules in accordance with another embodiment of the present invention will be described below with details with reference to Syntax 3. [Syntax 3] TttData (); bsSkipSyncflag; SmgData (); TempShapeData (); bsSkipSyncword; if (bsArbitraryDownmix). { ArbitraryDownmixData (); } With reference to Syntax 3, an unnecessary module can be skipped by using bsSkipSyncflag which is a flag indicating whether or not to use a synchronization word, and bsSkipSyncword, which is a synchronization word that can be placed at the end of a module to jump.

More specifically, if the bsSkipSyncflag flag is set in such a way that a synchronization word can be used, one or more modules between the bsSkipSyncflag flag and the synchronization word bsSkipSyncword, that is, the SmgDataO and TempShapeData () modules can be skipped. With reference to FIGURE 11, a bit stream may include a multi-channel header field that includes the header information necessary to reproduce a multichannel signal, a 3D presentation header field that includes the header information necessary to reproduce a signal submitted to 3D reduction mix, and a plurality of multichannel decoding information fields, which include the data necessary to reproduce a multichannel signal. In order to reproduce a multichannel signal, a decoding apparatus can skip the 3D presentation header field, and read data from the multichannel header field and the multi-channel decoding information fields. A method for skipping the 3D presentation header field is the same as the methods for jumping field described above with reference to FIGURE 10 and therefore a detailed description of said method will be omitted. With the objective of . play a signal subjected to mixing 3D reduction, a decoding apparatus can read data from the multi-channel decoding information fields and the 3D presentation header field. For example, a decoding apparatus can generate a signal subjected to 3D reductive mixing using a signal subjected to reductive mixing included in the multi-channel decoding information field and the HRTF coefficient information included in the signal subjected to 3D reductive mixing. FIGURE 12 is a block diagram of the coding / decoding apparatus for processing an arbitrary signal subjected to reductive mixing in accordance with one embodiment of the present invention. With reference to FIGURE 12, an arbitrary signal subjected to reductive mixing is a signal subjected to reductive mixing different from a signal subjected to reductive mixing generated by a multichannel encoder 801 included in an 800 coding apparatus. Detailed descriptions of the same processes as the processes of the modality of FIGURE 1 will be omitted. With reference to FIGURE 12, the coding apparatus 800 includes the multichannel encoder 801, a spatial information synthesis unit 802 and a comparison unit 803. The multi-channel encoder 801 subjects to reductive mixing a multi-channel signal input to a signal subjected to stereo or mono reduction mix, and general spatial information necessary to restore the multichannel signal from the signal subjected to the reductive mixture. Comparison unit 803 compares the signal subjected to reductive mixing with a signal subjected to arbitrary reductive mixing, and generates compensation information based on the result of the comparison. The compensation information is necessary to compensate the signal subjected to arbitrary reductive mixing in such a way that the signal subjected to arbitrary reductive mixing can be converted to be approximately the signal subjected to reductive mixing. A decoding apparatus can compensate for the signal subjected to arbitrary reductive mixing using the compensation information and restore a multichannel signal using the signal subjected to compensated arbitrary reductive mixing. The restored multi-channel signal is more similar than a multi-channel signal restored from the signal subjected to arbitrary reductive mixing generated by the multi-channel encoder 801 to the original multi-channel input signal. The compensation information may be a difference between the signal subjected to reductive mixing and the signal subjected to arbitrary reductive mixing. A decoding apparatus can compensate the signal subjected to arbitrary reductive mixing by adding, to the signal subjected to arbitrary reductive mixing, the difference between the signal subjected to reductive mixing and the signal subjected to reductive mixing. arbitrary The difference between the signal subjected to reductive mixing and the signal subjected to arbitrary reductive mixing can be the reductive mixing gain indicating the difference between the energy levels of the signal subjected to reductive mixing and the signal subjected to arbitrary reductive mixing. The reductive mixing gain can be determined for each frequency band, for each time / segment of time and / or for each channel. For example, a part of the reductive mixing gain can be determined for each frequency band, and another part of the reductive mixing gain can be determined for each time segment. The reductive mixing gain can be determined for each parameter band or for each frequency band optimized for the signal subjected to arbitrary reductive mixing. Parameter bands are frequency intervals to which spatial information of parameter type is applied. The deference between the energy levels of the signal subjected to reductive mixing and the signal subjected to arbitrary reductive mixing can be quantified. The resolution of the quantization levels to quantify the difference between the energy levels of the signal subjected to reductive mixing and the signal subjected to arbitrary reductive mixing can be the same or different in relation to the resolution of the quantization levels to quantify a CLD between the signal subjected to the reductive mixture and the signal subjected to the arbitrary reductive mixture. In addition, the quantification of the difference between the energy levels of the signal subjected to reductive mixing and the signal subjected to arbitrary reductive mixing may involve the use of all or some of the quantization levels to quantify the CLD between the signal submitted a reductive mixture and the signal subjected to arbitrary reductive mixing. Since the resolution of the difference between the energy levels of the signal subjected to reductive mixing and the signal subjected to arbitrary reductive mixing is generally less than the resolution of CLD between the signal subjected to reductive mixing and the signal subjected to arbitrary reductive mixing , the resolution of quantization levels to quantify the difference between the energy levels of the signal subjected to reductive mixing and the signal subjected to arbitrary reductive mixing can have a minute value compared to the resolution of the quantization levels to quantify the CLD between the signal subjected to reductive mixing and the signal subjected to arbitrary reductive mixing. The compensation information to compensate for the signal subjected to arbitrary reductive mixing may be the extension information that includes residual information that specifies multichannel input signal components that can not be restored using the signal subjected to arbitrary reductive mixing or reductive mixing gain. A decoding apparatus can restore multichannel input signal components that can not be restored using the signal subjected to arbitrary reductive mixing or reductive mixing gain using the extension information, thereby restoring a signal that can hardly be distinguished from the multichannel original input signal. Methods to generate the extension information are presented below. The multichannel encoder 801 can generate information about the multichannel input signal components that are not considered by the signal subjected to reductive mixing as the first extension information. An encoding apparatus can restore a signal almost indistinguishable from the original multichannel input signal by applying the first extension information to the generation of a multichannel signal using the signal subjected to reductive mixing and basic spatial information. Alternatively, the multichannel encoder 801 can restore a multichannel signal using the signal subjected to reductive mixing and the basic spatial information, and generate the difference between the restored multi-channel signal and the multichannel signal of original entry as the first extension information. The comparison unit 803 can generate, as a second extension information, information on components of the signal subjected to reductive mixing which are not considered by the signal subjected to arbitrary reductive mixing, that is, components of the signal subjected to reductive mixing that do not they can be compensated for the use of the reductive mixing gain. A decoding apparatus can restore the signal almost indistinguishable from the signal subjected to reductive mixing using the signal subjected to arbitrary reductive mixing and the second extension information. The extension information can be generated using various residual coding methods other than the method described above. The reductive mixing gain and extension information can both be used as compensation information. More specifically, the reductive mixing gain and extension information can both be obtained for a whole frequency band of the signal subjected to reductive mixing and can be used together as compensation information. Alternatively, the reductive mixing gain can be used as compensation information for a part of the frequency band of the signal subjected to reductive mixing, and the extension information can be used as information of compensation for another part of the frequency band of the signal subjected to reductive mixing. For example, the extension information can be used as compensation information for a low frequency band of the signal subjected to reductive mixing and the reductive mixing gain can be used as compensation information for a high frequency band of the signal subjected a reductive mixture. An extension information about portions of the signal subjected to reductive mixing, different from the low frequency band of the signal subjected to reductive mixing, such as peaks or notches that can significantly affect the sound quality can also be used as compensation information . The spatial information synthesis unit 802 synthesizes the basic spatial information (for example, a CLD, CTC, ICC, and CTD) and the compensation information, thereby generating spatial information. In other words, the spatial information that is transmitted to a decoding apparatus may include the basic spatial information, the reductive mixing gain, and the first and second extension information. The spatial information may be included in a bit stream together with the signal subjected to arbitrary reductive mixing and the bitstream may be transmitted to a decoding device. The extension information and the signal subjected to arbitrary reductive mixing can be encoded using an audio coding method such as an AAC method, an mp3 method, a BSAC method. The extension information and the signal subjected to arbitrary reductive mixing can be encoded using the same audio coding method or different audio coding methods. If the extension information and the signal subjected to arbitrary reductive mixing are encoded using the same audio coding method, a decoding apparatus can decode both the extension information and the signal subjected to arbitrary reductive mixing using a single decoding method of Audio. In this case, since the signal subjected to arbitrary reductive mixing can always be decoded, the extension information can also be decoded. However, since the signal subjected to arbitrary reductive mixing is generally input to a decoding apparatus as a pulse code modulation (PCM) signal, the type of audio codec used to encode the signal subjected to arbitrary reductive mixing can not be easily identified and therefore the type of audio codec used to encode the extension information may not be easily identified either. Accordingly, audio code information about the type of audio codec used to encode the signal subjected to arbitrary reductive mixing and the extension information can be inserted into a bit stream. More specifically, the audio codec information can be inserted into a specific configuration header field of a bitstream. In this case, a decoding apparatus can extract the audio codee information from the specific configuration header field of the bit stream and use the extracted audio codec information to decode the signal subjected to arbitrary reductive mixing and the extension information. On the other hand, if the signal subjected to arbitrary reductive mixing and the extension information is encoded using different audio coding methods, the extension information can not be decoded. In this case, since the end of the extension information can not be identified, no further decoding operation can be performed. In order to solve this problem, the audio code information on the audio codec types respectively used to encode the signal subjected to arbitrary reductive mixing and the extension information can be inserted into a configuration header field specific to a bitstream. Then, a decoding apparatus can read the audio codee information from the specific configuration header field of the bit stream and use the read information to decode the extension information. If the decoding apparatus does not include any decoding unit that can decode the extension information, the decoding of the extension information can not proceed further and the information next to the extension information can be read. The audio codec information on the type of audio codec used to encode the extension information may be represented by a syntax element included in a specific configuration header field of a bit stream. For example, the audio codec information may be represented by bsResidualCodecType, which is a 4-bit syntax element, as indicated in Table 1 below. Table 1 bsResidualCodecType Codee 0 AAC 1 MP3 2 BSAC 3 ... 5 Reserved Extension information can include not only the residual information but also channel expansion information. Channel expansion information is information needed to amplify a multichannel signal obtained through decoding using the spatial information in a multichannel signal with more channels. For example, channel expansion information may be information necessary to extend a 5.1-channel signal or a 7.1-channel signal in a 9.1-channel signal. The extension information may be included in a bitstream and the bit stream may be transmitted to a decoding apparatus. Then, the decoding apparatus can compensate the signal subjected to reductive mixing or expand a multichannel signal using the extension information. However, the decoding apparatus may skip the extension information instead of extracting the extension information from the bit stream. For example, in the case of the generation of a multichannel signal using a signal subjected to a 3D reduction mixture included in the bit stream or to generate a signal subjected to a 3D reduction mixture using a signal subjected to a reductive mixture included in the bit stream , the decoding device can skip the extension information. A method for skipping the extension information included in a stream of bits may be the same as one of the field jump methods described above with reference to FIGURE 10. For example, the extension information may be skipped using at least one bit size information that is attached to the beginning of a bit stream that includes the extension information and indicates the size in bits of the extension information, a synchronization word attached to the beginning or end of the field that includes the extension information, and a fixed bit size information indicating a fixed bit size of the information of extension. The bit size information, the synchronization word, and the fixed bit size information may all be included in a bit stream. The fixed bit size information may also be stored in a decoding apparatus. With reference to FIGURE 12, a decoding unit 810 includes a reductive mixing compensation unit 811, a 3D presentation unit 815, and a multichannel decoder 816. Reduction mixing compensation unit 811 compensates for a signal subjected to reductive mixing arbitrary using compensation information included in spatial information, such as using a reductive mixing gain or extension information. The 3D presentation unit 815 generates one subject to mixing Reductive 3D decoded by performing a 3D presentation operation on the signal subjected to compensated reductive mixing. The multi-channel decoder 816 generates a 3D multi-channel signal using the signal subjected to compensated reductive mixing and the basic spatial information that is included in the spatial information. The reductive mixing compensation unit 811 can compensate for the signal subjected to arbitrary reductive mixing in the following manner. If the compensation information is reductive mixing gain, Reduction Mixing Compensation Unit 811 compensates the energy level of the signal subjected to arbitrary reductive mixing using the reductive mixing gain such that the signal subjected to arbitrary reductive mixing can be converted into a signal similar to a signal submitted a reductive mixture. If the compensation information is second extension information, the reductive mixing compensation unit 811 can compensate for the components that are not in the signal subjected to arbitrary reductive mixing using the second extension information. The multichannel decoder 816 can generate a multichannel signal by sequentially applying the pre-matrix MI, the matrix of the mixture M2 and the post-matrix M3 to a signal subjected to the reducing mixture. In this case, the second information of The extension can be used to compensate the signal subjected to reductive mixing during the application of the M2 mixing matrix to the signal subjected to reductive mixing. In other words, the second extension information may be used to compensate for a signal subjected to a reducing mixture to which the pre-matrix MI has been applied. In accordance with what is described above, each of several channels can be selectively compensated by applying the extension information to the generation of a multichannel signal. For example, if the extension information is applied to a center channel of the mixing matrix M2, the left and right channel components of the signal subjected to reductive mixing can be compensated by the extension information. If the extension information is applied to a left channel of the mixing matrix M2, the left channel component of the signal subjected to reductive mixing can be compensated by the extension information. The reductive mixing gain and extension information can both be used as the compensation information. For example, a low frequency band of the signal subjected to arbitrary reductive mixing can be compensated using the extension information, and a high frequency band of the signal subjected to arbitrary reductive mixing can be compensated using the mixing gain reductive In addition, portions of the signal subjected to arbitrary reductive mixing, other than the low frequency band of the signal subjected to arbitrary reductive mixing, for example, peaks or notches that can greatly affect the sound quality, can be compensated using the information of extension. Information about the portion to be compensated for the extension information may be included in a stream of bits. An information indicating whether or not a signal subjected to reductive mixing included in a bit stream is a signal subject to arbitrary reductive mixing or not and information indicating whether or not the bit stream includes a compensation information may be included in the bitstream. In order to avoid cutting the signal subjected to reductive mixing generated by the coding unit 800, a signal subjected to reductive mixing can be divided by predetermined gain. The default gain can have a static value or a dynamic value. The reductive mixing compensation unit 811 can restore the signal subjected to original reductive mixing by compensating the signal subjected to reductive mixing, which is weakened in order to avoid cutting, using the predetermined gain. A signal subjected to arbitrary reductive mixing compensated by the reducing mix compensation unit 811 can be easily reproduced. Alternatively, a signal subjected to arbitrary reductive mixing not yet compensated can be input to the 3D presentation unit 815 and can be converted to a signal subjected to 3D reductive mixing decoded by the 3D presentation unit 815. With reference to FIGURE 12, Reduction mixer compensation unit 811 includes a first domain convert 812, a compensation processor 813, and a second domain converter 814. The first domain converter 812 converts the domain of a signal subjected to arbitrary reductive mixing into a domain predetermined. The compensation processor 813 compensates for the signal subjected to arbitrary reductive mixing in the predetermined domain, using compensation information, for example, reductive mixing gain or extension information. The compensation of the signal subjected to arbitrary reductive mixing can be effected in a QMF / hybrid domain. For this purpose, the first domain converter 812 can perform a QMF / hybrid analysis on the signal subjected to arbitrary reductive mixing. The first domain converter 812 can convert the domain of the signal subjected to arbitrary reductive mixing in a domain, different from the QMF / hybrid domain, for example, a frequency domain, for example, DFT or FFT domain. The compensation of the signal subject to arbitrary reductive mixing can also be performed in a domain, different from QMF / hybrid domain, eg, a frequency domain or a time domain. The second domain converter 814 converts the domain of the signal subjected to compensated arbitrary reductive mixing in the same domain as the signal subjected to the original arbitrary reductive mixture. More specifically, the second domain converter 814 converts the domain of the signal subjected to compensated arbitrary reductive mixing in the same domain as the signal subjected to the original arbitrary reductive mixture by the inverse realization of a domain conversion operation performed by the first converter domain 812. For example, the second domain converter 814 can convert the signal subjected to compensated arbitrary reductive mixing into a time domain signal by performing a QMF / hybrid synthesis on the signal subjected to compensated arbitrary reductive mixing. Also, the second domain converter 814 can perform IDFT or IFFT on the signal subjected to compensated arbitrary reductive mixing. The 3D presentation unit 815, such as the 3D display unit 710 illustrated in FIGURE 7, can perform a 3D display operation on the signal subjected to arbitrary reductive mixing compensated in a digital domain. frequency, a QMF / hybrid domain or a time domain. For this purpose, the 3D presentation unit 815 may include a domain converter (not illustrated). The domain converter converts the domain of the signal subjected to compensated arbitrary reductive mixing into a domain in which a 3D rendering operation must be performed or it converts the domain of a signal obtained by the 3D presentation operation. The domain in which the compensation processor 813 compensates for the signal subjected to arbitrary reductive mixing may be the same domain or a domain different from the domain in which the 3D presentation unit 815 performs a 3D presentation operation on the signal submitted to compensated arbitrary reductive mixture. FIGURE 13 is a block diagram of a 3D mixer / display mixer compensation unit 820 in accordance with one embodiment of the present invention. With reference to FIGURE 13, the 3D reduction / presentation mixer compensation unit 820 includes a first domain converter 821, a second domain converter 822, a 3D compensation / presentation processor 823, and a third domain converter 824. The 3D mixer / display mixer compensation unit 820 can perform both a compensation operation and a 3D presentation operation on a signal subjected to arbitrary reducing mixture in a single domain, thereby reducing the amount of computation of a decoding apparatus. More specifically, the converter of the first domain 821 converts the domain of the signal subjected to arbitrary reductive mixing into a first domain in which a compensation operation and a 3D presentation operation must be performed. The second domain converter 822 converts spatial information, including basic spatial information necessary for the generation of a multichannel signal and the compensation information necessary to compensate for the signal subjected to arbitrary reductive mixing, such that spatial information may become applicable in the first domain. The compensation information may include at least one of the following: reductive mixing gain and extension information. For example, the second domain converter 822 may map compensation information that corresponds to a parameter band in a QMF / hybrid domain to a frequency band such that the compensation information can easily become applicable in a frequency domain. . The first domain can be a frequency domain, for example a DFT or FFT domain, a QMF / hybrid domain or a time domain. Alternatively, the first domain can be a domain different from the domains presented here. During the conversion of the compensation information, a time delay may occur. In order to solve this problem, the second domain converter 822 can perform a time delay compensation operation in such a way that a time delay between the domain of the compensation information and the first domain can be compensated. The 3D compensation / display processor 823 performs a compensation operation on the signal subjected to arbitrary reductive mixing in the first domain using the converted spatial information and then performs a 3D display operation on the signal obtained by the compensation operation. The 3D compensation / display processor 823 can perform a compensation operation and a 3D display operation in a different order of order set here. The 3D compensation / display processor 823 can perform a compensation operation and a 3D display operation on the signal subjected to arbitrary reductive mixing at the same time. For example, the 3D 823 compensation / presentation processor can generate a signal subject to 3D reductive mixing compensated by performing a 3D operation on the signal subjected to arbitrary reductive mixing in the first domain using a new filter coefficient which is the combination of the compensation information and an existing filter coefficient typically used in the 3D presentation operation. The third domain converter 824 converts the domain of the signal subjected to the 3D reduction mixture generated by the 3D compensation / display processor 823 in a frequency domain. FIGURE 14 is a block diagram of a decoding apparatus 900 for processing a signal subjected to compatible reductive mixing according to one embodiment of the present invention. With reference to FIGURE 14, the decoding apparatus 900 includes a first multi-channel decoder 910, a reductive mixture compactibility processing unit 920, a second multi-channel decoder 930, and a 3D presentation unit 940. Detailed descriptions of the same decoding processes as the processes of the modality of FIGURE 1. A signal subjected to compatible reductive mixing is a signal subjected to reductive mixing that can be decoded by two or more multichannel decoders. In other words, a signal subjected to compatible reductive mixing is a signal subjected to reductive mixing initially optimized for a predetermined multichannel decoder and which can then be converted into a signal optimized for a multi-channel decoder, different from the predetermined multi-channel decoder, through a compatibility processing operation. With reference to FIGURE 14, we are going to consider that a signal subjected to compatible inlet reductive mix is optimized for the first multi-channel decoder 910. For the second multichannel decoder 930 to decode the signal subjected to compatible reductive input mix, the Reduce mix compatibility processing 920 can perform a compatibility processing operation on the signal subjected to reductive mixing compatible input so that the signal subjected to reductive mixing compatible input can be converted into a signal optimized for the second multichannel decoder 930. The first multi-channel decoder 910 generates a first multichannel signal by decoding the signal subjected to reductive mixing compatible input. The first multi-channel decoder 910 can generate a multi-channel signal through decoding simply by using the signal subjected to compatible input-reducing mix without the requirement of spatial information. The second multi-channel decoder 930 generates a second multi-channel signal using a signal subjected to reductive mixing obtained by the compatibility processing operation carried out by the processing unit of Reduce Mixing Compatibility 920. The 3D display unit 940 can generate a signal subjected to decoded 3D reductive mixing by performing a 3D presentation operation on the signal subjected to reductive mixing obtained by the compatibility processing operation performed per unit of 920. Redundant mixing compatibility request 920. A signal subjected to compatible reductive mixing optimized for a predetermined multichannel decoder can be converted into a signal subjected to reductive mixing used for a multi-channel decoder different from the predetermined multichannel decoder, using compatibility information, for example. investment matrix example. For example, when there is a first multichannel encoder and a second multichannel encoder using different coding methods and a first multichannel decoder and a second multichannel decoder using different coding / decoding methods, a coding apparatus can apply a matrix to a signal subjected to reductive mixing generated by the first multichannel encoder, thereby generating a signal subjected to compatible reductive mixing that is optimized for the second multichannel decoder. Then, a decoding apparatus can apply an inversion matrix to the signal subjected to compatible reductive mixing generated by the encoding apparatus, thereby generating a signal subject to compatible reductive mixing that is optimized for the first multichannel decoder. With reference to FIGURE 14, the reductive mixing compatibility processing unit 920 can perform a compatibility processing operation on the signal subjected to reductive mixing compatible input using an inversion matrix, thereby generating a signal subject to reductive mixing which is optimized for the second miliannal decoder 930. Information on the inversion matrix used by the reductive mixing compatibility processing unit 920 can be stored in the decoding apparatus 900 in advance or it can be included in a transmitted input bitstream. by an encoding device. In addition, the information indicating whether or not a signal subjected to reductive mixing is included in the input bit stream is a signal subjected to arbitrary reductive mixing or a signal subjected to reductive mixing can be included in the input bit stream. With reference to FIGURE 14, the reducing mix compatibility processing unit 920 includes a first domain converter 921, a compatibility processor 922, and a second domain converter 923. The first domain converter 921 converts the domain of the signal subjected to compatible reductive mixing input in a predetermined domain, and the compatibility processor 922 performs a compatibility processing operation using the compatibility operation such as for example an inversion matrix such that the signal subjected to compatible reductive mixing input in the predetermined domain can be converted into the optimized signal for the second multi-channel decoder 930. The compatibility processor 922 can perform a compatibility processing operation in a QMF / hybrid domain. For this purpose, the first domain converter 921 can perform a QMF / hybrid analysis on the signal subjected to the input compatible reductive mixture. Also, the first domain converter 921 can convert the domain of the signal subjected to reductive mixing compatible input into a domain, different from a QMF / hybrid domain, for example, a frequency domain such as, for example, a DFT domain or FFT, and the compatibility processor 922 can perform the compatibility processing operation in a domain, different from a QMF / hybrid domain, e.g., a frequency domain or a time domain. The second domain converter 923 converts into a domain of a signal subjected to compatible reductive mixing obtained by the compatibility processing operation. Plus specifically, the second domain converter 923 can convert the domain of the signal subject to the compatibility reducing mixture obtained by the compatibility processing operation in the same domain as the signal subjected to the original input compatible reductive mixture by the inverse realization of a domain conversion operation performed by the first domain converter 921. For example, the second domain converter 923 can convert a signal subjected to compatible reductive mixture obtained by the compatibility processing operation into the time domain signal by performing of a QMF / hybrid synthesis in the signal subjected to compatible reductive mixing obtained by the compatibility processing operation. Alternatively, the second domain converter 923 may perform IDFT or IFFT on the signal subjected to compatible reductive mixing obtained by the compatibility processing operation. The 3D display unit 940 can perform a 3D display operation on the signal subjected to compatible reductive mixing obtained by the compatibility processing operation in a frequency domain, a QMF / hybrid domain or a time domain. For this purpose, the 3D display unit 940 may include a domain converter (not shown). The domain converter converts the domain of the signal subjected to compatible reducing mix entry in a domain in which a 3D presentation operation must be performed or it converts the domain of a signal obtained by the 3D presentation operation. The domain in which the compatibility processor 922 performs a compatibility processing operation may be the same domain or a domain different from the domain in which the 3D presentation unit 940 performs a 3D presentation operation. FIGURE 15 is a block diagram of a 3D blend reduction / presentation compatibility processing unit 950 in accordance with one embodiment of the present invention. With reference to FIGURE 15, the redistribution / 3D rendering compatibility processing unit 950 includes a first domain converter 951, a second domain converter 952, a 3D 953 compatibility / presentation processor, and a third domain converter 954. The 3D blend reduction / presentation compatibility processing unit 950 performs a compatibility processing operation and a 3D display operation in a single domain, thereby reducing the amount of computation of a decoding apparatus. The first domain converter 951 converts a signal subject to a reductive mix compatible with input into a first domain in which a compatibility processing operation must be performed and in a 3D presentation operation. The second domain converter 952 converts the spatial information and the compatibility information, for example, an inversion matrix, in such a way that the spatial information and the compatibility information may become applicable in the first domain. For example, the second domain converter 952 maps an inversion matrix that corresponds to a parameter band in a QMF / hybrid domain to a frequency domain such that the investment matrix can easily become applicable in a frequency domain. The first domain can be a frequency domain, for example, a DFT domain or an FFT domain, a QMF / hybrid domain, or a time domain. Alternatively it may be a domain different from the domains established here. During the conversion of spatial information and compatibility information, a time delay may occur. In order to solve this problem, the second domain converter 952 can perform a time delay compensation operation in such a way that a time delay between the domain of the spatial information and the compensation information and the first domain can be compensated. The 3D 953 compatibility / rendering processor performs a compatibility processing operation on the signal subjected to compatible reductive mixing input in the first domain using the converted compatibility information and then performs a 3D presentation operation on a signal subjected to reductive mixing compatible obtained by the compatibility processing operation. The 3D 953 compatibility / presentation processor can perform a compatibility processing operation and a 3D presentation operation in a different order from that set forth herein. The 3D 953 compatibility / display processor can perform a compatibility processing operation and in the 3D display operation on the signal subjected to compatible input-reducing mix at the same time. For example, the 3D 953 compatibility / display processor can generate a signal subjected to 3D reductive mixing by performing a 3D presentation operation on the signal subjected to reductive mixing compatible input in the first domain using a new filter coefficient, which is the combination of the compatibility information and an existing filter coefficient typically used in the 3D presentation operation. The third domain converter 954 converts the domain of the signal subjected to 3D reduction mixing generated by the 3D 953 compatibility / presentation processor in a frequency domain. FIGURE 16 is a block diagram of a decoding apparatus for canceling - interference according to one embodiment of the present invention. With reference to FIGURE 16, the decoding apparatus includes a bit unpacking unit 960, a reductive mixing decoder 970, a 3D presentation unit 980, and an interference cancellation unit 990. Detailed descriptions of the same processing processes decoding that the decoding processes of the modality of FIGURE 1 were omitted. A signal output subjected to 3D reduction mixing by the 3D display unit 980 can be reproduced by a hearing aid. However, when the signal subjected to 3D reduction mixing is reproduced by distant speakers of a user, inter-channel interference is likely to occur. Accordingly, the decoding apparatus may include the interference cancellation unit 990 which performs an interference canceling operation on the signal subjected to 3D reduction mixing. The decoding apparatus can perform a sound field processing operation. A sound field information used in the sound field processing operation, that is, information 33 which identifies a virtual space the signal subjected to the 3D reduction mixture must be reproduced, it can be included in an input bit stream transmitted by an encoding apparatus or it can be selected by the decoding apparatus. The input bitstream may include reverberation time information. A filter used in the sound field processing operation can be controlled in accordance with the reverberation time information. A sound field processing operation may be performed differently for an initial part and a late reverberant part. For example, the initial part can be processed using an FIR filter, and the late reverberation part can be processed using an IIR filter. More specifically, a sound field processing operation can be performed in the initial part by performing a convolution operation in a time domain using an FIR filter or by performing a multiplication operation in a frequency domain and converting the result of the multiplication operation to a time domain. A sound field processing operation can be performed on the late reverberation part in a time domain. The present invention can be realized as readable code in computer written on a computer-readable recording medium. The computer-readable recording medium can be any type of recording device in which data is stored in a computer readable manner. Examples of computer-readable recording medium including ROM, RAM, CD-ROM, a magnetic tape, a floppy disk, optical data storage and a carrier wave (eg, data transmission over the Internet). The computer-readable recording medium can be distributed in several computer systems connected to a network in such a way that a computer-readable code is written there and executed from there in a decentralized manner. Functional programs, code and code segments required to perform the present invention can be easily interpreted by a person with ordinary skill in the art. In accordance with what has been described above, according to the present invention, it is possible to efficiently encode multichannel signals with 3D effects and adaptively restore and reproduce audio signals with optimum sound quality in accordance with the characteristics of a reproduction environment. INDUSTRIAL APPLICATION Other implementations are within the scope of the appended claims. For example, a grouping, data coding, and entropy coding in accordance with the present invention can be applied to various fields of application and various products. Storage means that store data to which an aspect of the present invention is applicable are within the scope of the present invention.

Claims

CLAIMS 1. A decoding method to restore a multi-channel signal, the decoding method comprises: extracting a signal subjected to three-dimensional (3D) reductive mixing and spatial information from an input bit stream; remove the 3D effects of the signal submitted to the 3D reduction mix by performing a 3D presentation operation on the signal submitted to the 3D reduction mixture; and generating a multichannel signal using the spatial information and a signal subjected to reductive mixing obtained by the removal. The decoding method according to claim 1, wherein the removal comprises the use of a reverse filter of a filter used to generate the signal subjected to 3D reduction mixing. 3. The decoding method according to claim 2, wherein the information about the filter is extracted from the input bit stream. The decoding method according to claim 1, wherein the removal comprises the use of an inverse function of a header-related transfer function (HRTF) used to generate the signal subjected to 3D reduction mixing. 5. The decoding method according to claim 4, wherein the information on coefficients of the HRTF or coefficients of the inverse function of the HRTF is extracted from the input bit stream. The decoding method according to claim 1, wherein the input bit stream includes at least one of the information indicating whether or not the input bitstream includes filter information that identifies a filter used for perform the 3D presentation operation and the information indicating whether or not the filter information specifies a reverse filter of a filter used to generate the signal subjected to 3D reductive mixing. The decoding method according to claim 1, wherein the removal comprises performing the 3D display operation on one of a discrete Fourier transformation domain (DFT), a fast Fourier transformation domain (FFT) , a quadrature mirror filter (QMF) / hybrid domain, and a time domain. 8. The decoding method according to claim 1, further comprising decoding the signal subjected to 3D reduction mixing. 9. A decoding method to restore a multi-channel signal, the decoding method comprises: extracting a signal subjected to 3D reduction mixture and spatial information from an input bit stream; generate a multichannel signal using the signal subjected to 3D reduction mix and spatial information; and remove 3D effects from the multichannel signal by performing a 3D presentation operation on the multichannel signal. 10. An encoding method for encoding a multi-channel signal with several channels, the coding method comprising: encoding the multichannel signal in a signal subjected to reductive mixing with fewer channels; generate spatial information about the plurality of channels; generating a signal subjected to 3D reductive mixing by performing a 3D presentation operation on the signal subjected to reductive mixing; and generating a bitstream including the signal subjected to 3D reduction mixing and spatial information. The coding method according to claim 10, wherein the generation of the signal subjected to 3D reductive mixing comprises carrying out the 3D presentation operation using a HRTF. 12. The coding method in accordance with the claim 11, wherein the bit stream includes at least one information on coefficients of the HRTF and information on coefficients of the inverse function of the HRTF. The coding method according to claim 10, wherein the generation of the signal subjected to 3D reductive mixing comprises performing the 3D presentation operation in a DFT domain, an FFT domain, a QMF / hybrid domain, and a time domain. 14. A coding method for encoding a multichannel signal with several channels, the coding method comprising: performing a 3D presentation operation on the multichannel signal; encoding a multichannel signal obtained by the 3D display operation in a signal subjected to 3D reduction mixing with fewer channels; generate spatial information about the various channels; and generating a bitstream including the signal subjected to 3D reduction mixing and spatial information. 15. A decoding apparatus for restoring a multichannel signal, the decoding apparatus comprising: a bit unpacking unit that extracts a signal subjected to encoded 3D reduction mixing and spatial information from an input bit stream; a reductive mixing decoder that decodes the signal subjected to encoded 3D reduction mixing; a 3D display unit that removes 3D effects from the signal subjected to decoded 3D reductive mixing obtained by the decoding performed by the reductive mixing decoder by performing a 3D presentation operation on the signal subjected to decoded 3D reductive mixing; and a multichannel decoder that generates a multichannel signal using spatial information and a signal subjected to reductive mixing obtained by the removal performed by the 3D presentation unit. 16. A decoding apparatus for restoring a multichannel signal, the decoding apparatus comprising: a bit unpacking unit that extracts a signal subjected to coded 3D reduction mixing and spatial information from an input bit stream; a reductive mixing decoder that decodes the signal subjected to encoded 3D reduction mixing; a multichannel decoder that generates a multichannel signal using the spatial information and a signal subjected to 3D reduction mixture obtained by the decoding performed by the reductive mixing decoder; and a 3D presentation unit that removes 3D effects from the multichannel signal by performing an operation of 3D presentation in multichannel signal. 17. An encoding apparatus for encoding a multi-channel signal with several channels, the coding apparatus comprising: a multi-channel encoder that encodes the multichannel signal in a signal subjected to reductive mixing with fewer channels and generates spatial information on the various channels; a 3D presentation unit that generates a signal subjected to 3D reduction mixing by performing a 3D presentation operation on the signal subjected to reductive mixing; a reductive mixing encoder that encodes the signal subjected to 3D reductive mixing; a bit packet unit that generates a bitstream including the signal subjected to encoded 3D reduction mix and the spatial information. 18. An encoding apparatus for encoding a multi-channel signal with several channels, the coding apparatus comprising: a 3D display unit performing a 3D display operation on the multichannel signal; a multichannel encoder that encodes a multichannel signal obtained by the 3D display operation in a signal subjected to 3D reduction mixing with fewer channels and generates a spatial information on the various channels; a reductive mixing encoder that encodes the signal subjected to reductive mixture; and a bit packet unit that generates a bitstream including the signal subjected to encoded 3D reduction mix and the spatial information. 19. A computer readable recording medium having a computer program for executing the decoding method of any of claims 1 to 9 or the encoding method of claims 10 to 14. 20. A bit stream comprising: a data field including information about a signal subjected to 3D reduction mixing; a filter information field that includes a filter information that identifies a filter used to generate the signal subjected to 3D reduction mixing; a first header field including information indicating whether the filter information field includes the filter information; a second header field including information indicating whether the filter information field includes filter coefficients or coefficients of a filter inverse of the filter; and a spatial information field that includes spatial information on several channels.