KR20060122734A - Encoding and decoding method of audio signal with selectable transmission method of spatial bitstream - Google Patents

Abstract

A coding-decoding method of an audio signal capable of selecting a space information transmission method is provided to transmit a multi-channel audio signal to transmission media of various types like a medium capable of additionally transmitting space information and a medium incapable of additionally transmitting the space information by selecting a method for embedding a space information bit stream in a down-mixed audio signal and transmitting the audio signal, a method for additionally transmitting the space information bit stream, or a method for embedding the space information bit stream in the down-mixed audio signal and additionally transmitting the audio signal. A multi-channel audio signal is down-mixed(1002). Space information is extracted from the multi-channel audio signal(1003). A space information bit stream is generated by using the space information(1004). A transmission method of the generated space information bit stream is selected(1005). The entire bit stream including the space information bit stream and the down-mixed audio signal is generated according to the selected method(1006).

Description

ENCODED AND DECODING METHOD OF AUDIO SIGNAL WITH SELECTABLE TRANSMISSION METHOD OF SPATIAL BITSTREAM}

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a diagram illustrating a method for a human to recognize spatial information about an audio signal in the present invention.

2 is a block diagram of a spatial encoder according to the present invention.

Figure 3 is a detailed block diagram of the embedding portion constituting the spatial encoder of Figure 2 according to the present invention.

4 is a diagram of a first method of reordering spatial information bitstreams in accordance with the present invention.

5 is a diagram of a second method for reordering spatial information bitstreams in accordance with the present invention.

6A is a diagram of the configuration of a spatial information bitstream for embedding in accordance with the present invention.

FIG. 6B is a detailed diagram of the configuration of a spatial information bitstream for embedding in FIG. 6A; FIG.

7 is a block diagram of a spatial decoder according to the present invention.

8 is a detailed block diagram of an embedded signal decoder constituting a spatial decoder according to the present invention.

9 is a diagram of a case of reproducing an audio signal according to the present invention in a general PCM decoder.

10 is a flowchart of an encoding method for embedding a spatial information bitstream in a downmixed audio signal in accordance with the present invention.

11 is a flowchart of a method of decoding a spatial information bitstream embedded in a downmixed audio signal in accordance with the present invention.

12 illustrates a frame (or subframe) size of a spatial information bitstream embedded in a downmixed audio signal in accordance with the present invention.

13 illustrates a spatial information bitstream embedded in a downmixed audio signal with a constant size in accordance with the present invention.

FIG. 14A is a diagram illustrating a first method for solving a time alignment problem of a spatial information bitstream embedded at a fixed size. FIG.

FIG. 14B illustrates a second method for solving the time alignment problem of a spatial information bitstream embedded at a fixed size. FIG.

15 is a diagram illustrating that a spatial information bitstream is combined with a downmix audio signal in units of a frame size applied in a decoding step.

16 is a flow diagram of a method for encoding a spatial information bitstream embedded in various sizes in a downmixed audio signal in accordance with the present invention.

FIG. 17 is a flow diagram of a method for encoding a spatial information bitstream embedded with a constant size in a downmixed audio signal in accordance with the present invention. FIG.

18 illustrates a first method of embedding a spatial information bitstream in an audio signal downmixed into at least two channels in accordance with the present invention.

19 illustrates a second method of embedding a spatial information bitstream in an audio signal downmixed into at least two channels in accordance with the present invention.

20 illustrates a third method of embedding a spatial information bitstream in an audio signal downmixed into at least two channels in accordance with the present invention.

21 illustrates a fourth method of embedding a spatial information bitstream in an audio signal downmixed into at least two channels in accordance with the present invention.

FIG. 22 illustrates a fifth method for embedding a spatial information bitstream in an audio signal downmixed into at least two channels in accordance with the present invention. FIG.

23 illustrates a sixth method of embedding a spatial information bitstream in an audio signal downmixed into at least two channels in accordance with the present invention.

FIG. 24 illustrates a seventh method of embedding a spatial information bitstream in an audio signal downmixed into at least two channels in accordance with the present invention. FIG.

25 is a flowchart of a method for encoding a spatial information bitstream embedded in a downmixed audio signal of two channels in accordance with the present invention.

FIG. 26 is a flow diagram of a method of decoding a spatial information bitstream embedded in a downmixed audio signal of two channels in accordance with the present invention. FIG.

27 is a diagram of a first spatial encoder capable of selecting a method capable of transmitting spatial information bitstream in accordance with the present invention.

FIG. 28 is a diagram of a second spatial encoder capable of selecting a method for transmitting a spatial information bitstream in accordance with the present invention. FIG.

29 is a diagram illustrating the configuration of a bitstream for separately transmitting a spatial information bitstream in the form of an MPEG bitstream according to the present invention.

30 is a flowchart of a method for transmitting a spatial information bitstream in accordance with the present invention.

FIG. 31 is a diagram of a first spatial decoder capable of decoding the spatial information bitstream transmitted in accordance with the present invention. FIG.

32 illustrates a second spatial decoder capable of decoding the spatial information bitstream transmitted in accordance with the present invention.

33 is a diagram of a third spatial decoder capable of decoding the spatial information bitstream transmitted in accordance with the present invention.

34 is a flowchart of a method of decoding using a first spatial decoder according to the present invention.

35 is a flowchart of a method of decoding using a second spatial decoder according to the present invention.

36 is a flowchart of a method of decoding using a third spatial decoder according to the present invention.

* Explanation of symbols for main parts of the drawings

101.Remote sound source 102.Direct sound wave

104. Reflected Sound Wave 201. Multichannel Audio Signal

202. Artistic downmix signal 203. Downmix section

204. Spatial information extraction unit 205. Downmixed audio signal

206. Spatial information encoding section 207. Embed section

208 Embedded audio signal 303 Buffer

304. Masking limit calculation unit 305. Bitstream reconstruction unit

306. Encoding unit 401. Spatial information bitstream

402.Bitplane 405.Frame

601.Header 602.Frame data

603.Sinkword 604.k Value

606. Error detection code or error correction code 702. Embedded signal decoder

703. Spatial information decoder 704. Multichannel generator

902. Sync word search unit 903. Header decoding unit

904.Data Inverse Deformer 1302.TS Header

1303.TS (Transport Stream) 1406.TS Syncword

1408.Flag 1409.Position value

2704. Spatial information extraction section 2708. Transmission method selection section

2903.Extended Bitstream 2906.Auxiliary Data Header

2907.Secondary Data Bitstream

The present invention relates to an encoding-decoding method for spatial information of a multichannel audio signal.

Recently, various coding techniques and methods for digital audio signals have been developed, and related products have been produced. In addition, coding methods for converting a mono or stereo audio signal into a multichannel in a decoding step using spatial information of a multichannel audio signal have been developed, and a product for this has been put into practical use. In this case, the mono or stereo audio signal and the spatial information are compressed and transmitted using various compression methods such as AAC (Advanced Audio Coding).

However, some recording media do not have an area for storing spatial information. Therefore, in the above case, the audio signal reproduced through decoding by storing or transmitting only a mono or stereo audio signal is reproduced as a mono or stereo audio signal rather than a multichannel, so that the sound quality is monotonous. In addition, when spatial information is transmitted only by one method together with the downmixed audio signal, various types of decoders cannot be used.

Accordingly, an object of the present invention, which is proposed to solve the above problems, is to provide an encoding method capable of selecting a method of transmitting spatial information in coding a multichannel audio signal. Another object of the present invention is to provide a method for decoding spatial information encoded and transmitted in the above manner.

In order to achieve the above object, the present invention comprises the steps of downmixing the multichannel audio signal and extracting spatial information from the multichannel audio signal; Generating a spatial information bitstream using the spatial information; Selecting a method of transmitting the generated spatial information bitstream; According to the selected method, generating a full bitstream including the spatial information bitstream and the downmix audio signal; provides a method of encoding a multi-channel audio signal comprising a. Here, the transmission method is a method of embedding the spatial information bitstream in the downmix audio signal, and transmitting the spatial information bitstream separately from the downmix audio signal, or the spatial information bitstream. May be embedded in the downmixed audio signal and transmitted separately from the downmixed audio signal.

In addition, to achieve the above object, the present invention comprises the steps of downmixing the multichannel audio signal, and extracting spatial information from the multichannel audio signal; Generating a spatial information bitstream using the spatial information; Embedding the generated spatial information bitstream into the downmix audio signal; Generating an entire bitstream such that the spatial information bitstream includes an embedded downmix audio signal, and determining whether to include the spatial information bitstream separately in the entire bitstream; A method of encoding a channel audio signal is provided. The entire bitstream may be configured not to include the spatial information bitstream separately, or may be configured to include the spatial information bitstream separately. The entire bitstream may include identification information about the transmission method.

In addition, in order to achieve the above object, the present invention comprises the steps of: receiving an entire bitstream including a downmix audio signal in which the spatial information bitstream is embedded; Extracting a spatial information bitstream embedded in the downmix audio signal; And converting the downmix audio signal into a multichannel audio signal using the spatial information obtained by decoding the spatial information bitstream. Here, identification information indicating that the spatial information bitstream is embedded in the downmix audio signal may be extracted from the entire bitstream, and the spatial information bitstream may be extracted using the extracted identification information.

In addition, in order to achieve the above object, the present invention comprises the steps of: receiving an entire bitstream comprising a spatial information bitstream and a downmix audio signal; Extracting a spatial information bitstream transmitted separately from the downmix audio signal from the entire bitstream; And converting the downmix audio signal into a multichannel audio signal using the spatial information obtained by decoding the spatial information bitstream. The spatial information bitstream may be stored and transmitted in a data track of a CD, stored and transmitted in an extended bitstream of an MPEG bitstream, or stored and transmitted in an auxiliary data area in a core codec bitstream of an MPEG bitstream. Further, the decoding method includes extracting identification information indicating that the spatial information bitstream was transmitted separately from the downmix audio signal from the entire bitstream before step (b).

In addition, in order to achieve the above object, the present invention comprises the steps of receiving a full bitstream including a downmix audio signal embedded with the spatial information bitstream and the spatial information bitstream transmitted separately; Extracting a spatial information bitstream from the downmix audio signal, decoding the extracted spatial information bitstream, or decoding the separately transmitted spatial information bitstream; And converting the downmix audio signal into a multichannel audio signal using the spatial information obtained by decoding the spatial information bitstream. In this case, identification information indicating that the spatial information bitstream is embedded and transmitted in the downmix audio signal and is transmitted separately from the downmix audio signal may be extracted from the entire bitstream.

In addition, in order to achieve the above object, the present invention comprises the steps of downmixing the multichannel audio signal and extracting spatial information from the multichannel audio signal; Generating a spatial information bitstream for each frame using the spatial information; The spatial information bitstream and the downmixed audio signal are combined to form an entire bitstream, wherein the frame size (N) of the spatial information bitstream is the downlink by the frame size (S) to which spatial information is decoded and applied. Combined with the mixed audio signal; provides a method of encoding a multi-channel audio signal comprising a. In this case, location information regarding an application range of the spatial information bitstream may be inserted into a header of the spatial information bitstream. In addition, a sync word for a start position of the spatial information bitstream may be inserted in a header for the spatial information bitstream.

In addition, in order to achieve the above object, the present invention comprises the steps of: receiving an entire bitstream comprising a downmixed audio signal combined with a spatial information bitstream; Extracting and decoding the spatial information bitstream combined with the downmixed audio signal in a frame size (S) unit in which spatial information is decoded and applied from the entire bitstream. Provides a method for decoding into a signal. Here, position information to which the spatial information bitstream is applied may be read from the entire bitstream.

In addition, in order to achieve the above object, the present invention is generated such that an audio signal includes a downmixed audio signal and a spatial information bitstream, and the spatial information bitstream is combined with the downmixed audio signal to form an entire bitstream. Comprising a configuration, but provides a method for generating an audio signal characterized in that it is generated to be combined with the downmix audio signal in the unit of the frame size (S) to be applied by decoding the spatial information bitstream.

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention that can specifically realize the above object will be described.

1 shows a method for a human to recognize spatial information about an audio signal in the present invention. The coding method for a multichannel audio signal is based on the fact that a human perceives the audio signal as a three-dimensional space. I use it. Such parameters, called "spatial parameters" for indicating spatial information of a multichannel audio signal, include channel level differences (CLD), inter channel coherences (ICC), channel time differences (CTD), and the like. The CLD denotes an energy difference between two channels, the ICC denotes a correlation between two channels, and the CTD denotes a time difference between two channels.

How a human perceives an audio signal spatially and how the concept of the spatial parameter is generated is shown in FIG. 1. Direct sound wave 103 from the remote source 105 arrives at the human left ear 107, and another direct sound wave 102 is diffracted around the head to the right ear 106. Will be reached. The two sound waves 102 and 103 show a difference in arrival time and energy level, and this difference generates the CTD and CLD parameters. Also, if the reflected sound waves 104 and 105 reach both ears, or if the sound source 105 is dispersed, uncorrelated sound waves will reach both ears, which will generate the ICC parameter. . By using the spatial parameters generated as described above, the multichannel audio signal may be transmitted as a mono or stereo signal and then output again to the multichannel. The present invention provides a method in which the spatial information, that is, the spatial parameters are embedded in the mono or stereo audio signal, transmitted, and then reproduced as a multichannel audio signal.

2 shows a block diagram of a spatial encoder according to the present invention. As shown, first the spatial encoder receives a multichannel audio signal 201. Where N is the number of input channels. The multichannel audio signal 201 is an audio signal Lo and Ro 205 downmixed by the down-mix unit 203. The downmixed audio signal corresponds to a PCM signal and will be described herein as a downmixed audio signal for convenience. The downmixed audio signal 205 may comprise a mono or stereo audio signal. In the present specification, a stereo audio signal will be described as an example for convenience, but the present invention is not limited thereto. The spatial information of the multichannel audio signal, that is, the spatial parameter, is extracted from the multichannel audio signal 201 by the spatial information extractor 203. In this case, spatial information refers to downmixing a multi-channel (eg, Left, Right, Center, Left surround, Right surround, etc.) audio signal, transmitting the downmixed audio signal 205, and transmitting the downmixed audio signal. Refers to information about an audio signal channel used when upmixing the downmixed audio signal back to a multichannel. Alternatively, the downmixed audio signal 205 may be generated using an externally provided downmixed audio signal, for example an artistic down-mix signal 202. .

The spatial information extracted by the spatial information extractor 203 is encoded by the spatial information encoder 206 into a spatial information bitstream for transmission and storage. The spatial information bitstream is appropriately modified and inserted directly into the signal to be transmitted by the embedding unit 207, ie, the downmixed audio signal 205, where a "Digital Audio Embeded Method" may be used. have. For example, the downmixed audio signal 205 is stored in a storage medium (eg, stereo CD) that is difficult to store spatial information, or in a manner such as SPDIF (Sony / Philips Digital Interface). In the case of a raw PCM audio signal to be transmitted by a mobile station, there is no ancillary data field capable of storing a spatial information bitstream, unlike in the case of compression encoding such as AAC. In this case, if the "digital audio embedding technique" is used, the spatial information bitstream may be embedded in the raw PCM audio signal without sound distortion, and the audio signal in which the spatial information bitstream is embedded is a general decoder. Is indistinguishable from the original signal. That is, the output signal Lo '/ Ro' 208 in which the spatial information bitstream is embedded may be regarded as the same signal as the input signal Lo / Ro 205 from a general PCM decoder.

The "digital audio embedding method" includes a bit replacement coding method, an echo hiding method, a spread-spectrum-based method, and the like. The bit substitution encoding method is a method of inserting desired information by transforming least significant bits of a quantized audio sample, and using a characteristic that deformation of least significant bit in an audio signal has little effect on the quality of an audio signal. The echo insertion method is a method of inserting an echo of a size small enough to be inaudible to the human ear. In the spread spectrum communication method, after converting an audio signal into a frequency domain through a discrete cosine transform, a discrete fourier transform, and the like, the desired information, which is made with a binary number, is spread with a pseudo noise (PN) sequence. To add to the audio signal converted into the frequency domain. In the present invention, a description will be made mainly on the bit substitution encoding method of the embedding method, but the present invention is not limited to the bit substitution encoding method.

3 is a detailed block diagram of the embedding part 207 constituting the spatial encoder of FIG. 2 according to the present invention. When embedding the spatial information bitstream in the downmixed audio signal by the bit substitution encoding method, it is preferable to use only the least significant 1 bit as the insertion bit value (hereinafter referred to as the K value) that can embed the spatial information bitstream. Instead, the K (K> 0) bits can be used according to a predetermined method. The K bit may use the least significant bit value of the downmixed audio signal, but is not limited to the least significant bit value. The method defined here means, for example, obtaining a masking threshold according to a psychoacoustic model and allocating an appropriate bit according to the masking threshold. As shown, the downmixed audio signal Lo / Ro 301 is transmitted via the buffer 303 in the embedding portion to the encoding portion 306. The masking limit value calculator 304 divides the input audio signal into a predetermined section (for example, a block) and calculates a masking limit value for the section. In addition, the masking limit value calculator 304 obtains an insertion bit value of the downmixed audio signal, that is, a K value, which can be changed without generating an acoustic distortion according to the masking limit value. In other words, the number of bits that can be used to embed the spatial information bitstream into the downmixed audio signal is allocated for each block. In the present specification, a block refers to a data unit inserted using one insertion bit value (that is, a K value) existing in a frame. One or more blocks may exist in one frame. Therefore, if the length of the frame is fixed, the length of the block may decrease as the number of blocks increases. Once the available K value is determined, the K value may be included in the spatial information bitstream. That is, the bitstream reconstruction unit 305 may reconstruct the spatial information bitstream to include the K value. In this case, the spatial information bitstream may include a sync word, an error detection code, or an error correction code.

The reconstructed spatial information bitstream may be rearranged into an embeddable form. The rearranged spatial information bitstream is embedded in the downmixed audio signal by the encoding unit 306, and the spatial information bitstream is output to the embedded audio signal Lo '/ Ro' 307. In this case, the spatial information bitstream may be embedded in K bits of the downmixed audio signal. The K value may have a fixed value within the block, or may have a variable K value depending on the shape of the audio signal (eg, temporal shape) within the block. In any case, the K value is inserted as additional information and transmitted to the decoder in the reconstruction or rearrangement of the spatial information bitstream, and the decoder can restore the spatial information bitstream data using the additional information.

As described above, the spatial information bitstream is coupled to the downmixed audio signal on a block-by-block basis. Various coupling methods are used in the above process. The first method simply replaces the lower K bits of the downmixed audio signal with zeros and then adds the modified spatial information bitstream data. For example, if the K value is 3, one sample data of the downmixed audio signal is 11101101, and the spatial information bitstream data to be embedded is 111, the lower 3 bits of the 11101101 are replaced with 0 to be 11101000, The spatial information bitstream data 111 is then added to make 11101111.

The second method is to use a dithering method, first subtracting the modified spatial information bitstream data from the downmixed audio signal, and then requantizing the downmixed audio signal based on the K value, And adding the modified spatial information bitstream data to the quantized downmixed audio signal. For example, if the value of K is 3, one sample data of the downmixed audio signal is 11101101, and the spatial information bitstream data to be embedded is 111, the value 11110 is subtracted from 111 to 11100110, and the lower 3 bits or more And requantize to 11101000 (rounded), then add 111 to 11101111.

Since the spatial information bitstream to be embedded in the downmixed audio signal is an arbitrary bitstream, it may not have a white noise characteristic. Since it is advantageous to add a white noise signal to the downmixed audio signal, it may be added to the downmixed audio signal after whitening the spatial information bitstream. The whitening may be applied to the spatial information bitstream excluding the syncword. The whitening refers to making the volume of an audio signal into a random signal having the same or almost similar magnitude in all frequency domains. In addition to the whitening, the second method may minimize noise distortion by applying a noise shaping technique to the requantization process. The noise shaping may be performed by modifying a noise characteristic such that energy of quantization noise generated in a requantization process is shifted to a high frequency band of an audible frequency band or higher, or obtaining a masking threshold value from a corresponding audio signal, A process of generating a time-varing) filter and modifying the characteristics of noise generated in the requantization process by the filter.

4 illustrates a first method of reordering spatial information bitstreams in accordance with the present invention. As described above, the spatial information bitstream may be rearranged into an embeddable form using the K value. In this case, the spatial information bitstream may be rearranged in various ways and embedded in the downmixed audio signal. FIG. 4 corresponds to one of the above methods. The first method is to rearrange the spatial information bitstream to distribute the spatial information bitstream for the corresponding block in units of K bits and to embed the same sequentially. As shown, if the K value is 4 and one block 405 consists of N samples 403, the spatial information bitstream 401 can be rearranged so that it can be sequentially embedded in the lower 4 bits of each sample. have. As described above, the present invention is not limited to embedding the spatial information bitstream only in the lower 4 bits of each sample. Within the lower K bits of each sample, the spatial information bitstream may be embedded from a higher bit (MSB (Most Significant Bit) first) as shown, or from a lower bit (Least Significant Bit (LSB) first). Can be.

Arrow 404 in FIG. 4 indicates the direction in which it is embedded, and the numbers in parentheses indicate the data reordering order. The illustrated bitplane 402 refers to a constant bit layer composed of a plurality of bits. If the number of bits in the spatial information bitstream to be embedded in the block 405 is less than the embeddable number of bits, fill the remaining number of bits with zero (406), insert a random signal, or the original downmix. Can be replaced with the audio signal. For example, when the number of samples (N) constituting the block is 100 and the K value is 4, the number of bits (W) embedable in the block is W = N * K = 100 * 4 = 400 bits. If the number of bits (V) of the spatial information bitstream to be embedded is 390 bits (i.e., V <W), the remaining 10 bits are filled with zeros, inserted random signals, or the original downmixed audio signal. Alternately, you can insert a tail sequence that indicates the end of the data. The terminal bit string refers to a bit string indicating the end of the spatial information bit stream in the block.

5 illustrates a second method of reordering spatial information bitstreams in accordance with the present invention. The second method is to rearrange the spatial information bitstream 501 in the order of bit planes 502. That is, the spatial information bitstream is sequentially embedded in bits (ie, LSBs) of the downmixed audio signal to be embedded block by block. In this case, the spatial information bitstream may be sequentially embedded from the lower bits of the downmixed audio signal for each block, but the present invention is not limited thereto. For example, if the number of samples (N) constituting the block is 100 and the K value is 4, first, the least significant 100 bits constituting the bitplane 502 0 are filled first, and then the bitplane 502 1 is filled. You can proceed by filling the 100 bits to make up.

Arrow 505 in FIG. 5 indicates the direction in which it is embedded, and the numbers in parentheses indicate the data reordering order. The second method may be particularly advantageous for extracting Sync Word at any location. When finding the starting position of the inserted spatial information bitstream from the rearranged and encoded signal as described above, it is possible to extract and search only the LSB. In addition, the effect of using only the minimum LSB can be expected according to the number of bits (V) of the spatial information bitstream to be embedded. In this case, if the number of embeddable bits (W) in the block 504 is larger than the number of bits (V) of the spatial information bitstream to be embedded, the remaining number of bits is filled with zero as described above (506), or a random signal is inputted, It may be replaced with the original downmixed audio signal, or a terminal bit string indicating the end of data may be used. It is particularly advantageous to use the downmixed audio signal as it is.

6A illustrates a configuration of a spatial information bitstream for embedding in accordance with the present invention. As described above, the spatial information bitstream 607 is reconstructed by the bitstream reconstruction unit 305 to include a sync word (603) and a K value 604 for the spatial information bitstream, so that the embedding for the embedding is performed. It may be a spatial information bitstream. In the reconstruction process, an error detection code or an error correction code 606 and 608 that can determine whether the spatial information bitstream 607 is damaged during transmission and storage. May be included in the spatial information bitstream for embedding. The error detection code may include a cyclic redundancy check (CRC). The error detection code or error correction code may be divided into two stages. The error detection code 1 or error correction code 1 606 for the header 601 including the K values and the frame data of the spatial information bitstream ( Error detection code 2 or error correction code 2 608 for 602 may be included separately. In addition, other information 605 may be separately included in the spatial information bitstream for embedding. The other information 605 may include identification information about a reordering method of the spatial information bitstream.

FIG. 6B is a detailed diagram of the spatial information bitstream for embedding of FIG. 6A. As shown in FIG. 6B, an embodiment in which one frame of the spatial information bitstream 610 is composed of two blocks is shown, but the present invention is not limited to the above embodiment. Spatial information bitstream for embedding in FIG. 6B also includes a syncword 612, K values (K1, K2, K3 and K4) 613, 614, 615 and 616, other information 617, error detection code or error correction. It can be configured to include codes 618 and 623. The spatial information bitstream 610 is composed of two blocks. In the case of a stereo audio signal, block 1 is block 1 619 for the left channel and block 1 620 for the right channel. Block 2 may also be composed of block 2 621 for the left channel and block 2 622 for the right channel. Although shown in FIG. 6B for the stereo audio signal, the present invention is not limited to the stereo audio signal only. The insertion bit value (K value) for the blocks is included in the header portion. K1 613 is the insertion bit value for the left channel of block 1, K2 614 is the insertion bit value for the right channel of block 1, K3 615 is the insertion bit value for the left channel of block 2 , K4 616 corresponds to the insertion bit value for the right channel of block 2. In addition, the error detection code or error correction code may be divided into two stages. The error detection code 1 or error correction code 1 618 for the header 609 including K values and the frame of the spatial information bitstream Error detection code 2 or error correction code 2 623 for the data 611 may be included separately.

7 is a block diagram of a spatial decoder according to the present invention. As shown, the spatial decoder receives the audio signal Lo '/ Ro' 701 in which the spatial information bitstream is embedded. The audio signal in which the spatial information bitstream is embedded may include a mono or stereo audio signal. For convenience, the present invention is described with reference to a stereo audio signal, but is not limited thereto. The embedded signal decoder 702 may detect and decode a spatial information bitstream from the audio signal 701. The embedded spatial information bitstream obtained by the embedded signal decoder 702 is an encoded spatial information bitstream, and the encoded spatial information bitstream enters an input of the spatial information decoder 703. The spatial information decoder 703 decodes the encoded spatial information bitstream and outputs the decoded spatial information bitstream to the multichannel generator 704. The multichannel generator 704 may receive the downmixed audio signal 701 and spatial information obtained through decoding and output the multichannel audio signal 705.

8 illustrates in detail the embedded signal decoder constituting the spatial decoder according to the present invention. An audio signal Lo '/ Ro' 801 embedded with spatial information is input to the embedded signal decoder, and the sync word search unit 802 detects a sync word from the input audio signal 801. . When the syncword is detected, the header decoding unit 803 decodes the header thereafter. In this case, if a whitening or noise shaping technique is applied, the data inverse transform unit 804 may process the data after the reverse processing. The header decoding obtains additional information such as a K value, and rearranges the rearranged spatial information bitstream using the additional information to obtain the original spatial information bitstream 805. The spatial information bitstream 805 may be the same as the spatial information bitstream before being modified in the encoding step. In addition, by detecting the sync word, sync position information, that is, frame alignment information 806, may be obtained to align frames of the downmixed audio signal and the spatial information bitstream.

9 illustrates a case in which an audio signal according to the present invention is reproduced by a general PCM decoder. That is, FIG. 9 illustrates a case in which the audio signal Lo '/ Ro' 901 in which the spatial information bitstream is embedded is applied as an input of a general PCM decoder. In this case, the general PCM decoder recognizes the audio signal Lo '/ Ro' 901 in which the spatial information bitstream is embedded as a normal stereo audio signal and reproduces sound, which is audio before spatial information is embedded in terms of sound quality. It is not distinguished from the signal 902. Accordingly, the audio signal embedded with the spatial information according to the present invention has a compatibility of reproducing a normal stereo audio signal through a general PCM decoder, and a multichannel audio signal may be provided in a decoder capable of multichannel decoding.

10 shows a flowchart of an encoding method for embedding a spatial information bitstream in a downmixed audio signal according to the present invention. First, the audio signal is downmixed 1002 from the multichannel audio signal 1001. The downmixed audio signal may comprise a mono or stereo signal. In addition, the spatial information is extracted 1003 from the multi-channel audio signal 1001, and a spatial information bitstream is generated 1004 using the spatial information. The spatial information bitstream is then embedded 1005 into the downmixed audio signal and the entire bitstream including the downmixed audio signal in which the spatial information bitstream is embedded 1006. Here, the present invention may include obtaining a K value using the downmixed audio signal and embedding a spatial information bitstream in the K bit.

11 shows a flowchart of a method of decoding a spatial information bitstream embedded in a downmixed audio signal according to the present invention. First, the spatial decoder receives 1101 a bitstream including a downmixed audio signal in which a spatial information bitstream is embedded, and detects 1102 the downmixed audio signal from the bitstream. It also detects and decodes 1103 the spatial information bitstream from the entire bitstream. The spatial information is extracted 1104 through the decoding, and the downmixed audio signal is decoded 1105 using the extracted spatial information. The downmixed audio signal may be decoded into two channels or decoded into multichannels. The present invention includes reading information on the embedding method and K value of the spatial information bitstream into a downmixed audio signal, and decoding the spatial information bitstream using the read embed method and the K value. can do.

12 illustrates a frame size of a spatial information bitstream embedded in various sizes in a downmixed audio signal according to the present invention. In the present invention, "frame" refers to a unit capable of independent decoding of a predetermined length having one header. In general, "frame" in the present specification means "inserted frame". As shown, a frame size N (hereinafter, referred to as an "inserted frame size") corresponding to a unit for embedding a spatial information bitstream in a downmixed audio signal corresponds to a unit for decoding and applying spatial information. To have a size equal to the frame size S of the spatial information bitstream (hereinafter referred to as " decoded frame size ") (for (a)), or to be a multiple of S (for (b)), or There is a method (for (c)) in which S is a multiple of N. As shown in (a), when N = S, the decoding frame size (S, 1201) and the insertion frame size (N, 1202) are the same, there is an advantage that the decoding process is easy. On the other hand, in the case of N> S, as shown in (b), a plurality of decoding frames 1203 are bundled and transmitted with one insertion frame size (N, 1204), whereby a header or an error detection code (for example, The number of bits added due to the CRC) can be reduced. In this case, a frame size value and the like may be inserted as additional information in the header. As shown in (c), in the case of N <S, one decoding frame (S) 1205 may be configured by combining several insertion frames (N, 1206).

13 illustrates a spatial information bitstream embedded in a downmixed audio signal with a constant size in accordance with the present invention. In the case of (a), (b) and (c) illustrated in FIG. 12, the insertion frame and the decoding frame are configured to be aligned with each other. On the other hand, in some cases, an upper packet having a fixed size, such as a transport stream (Transport Stream (TS) 1303), may be configured and transmitted. That is, regardless of the size of the decoding frame 1301 of the spatial information bitstream, the spatial information bitstream 1301 may be bundled in a packet unit having a predetermined size, and the TS header 1302 or the like may be inserted into the packet and transmitted.

According to the method, the masking threshold value is different for each block according to the characteristics of the downmixed audio signal, which results in a difference in the maximum number of bits (K_max) that can be allocated without damaging the sound quality of the downmixed audio signal. In consideration, it is necessary to vary the data rate of the spatial information bitstream. For example, when K_max is insufficient to represent all the spatial information bitstreams required by the corresponding block, data can be transmitted only up to K_max, and the rest can be transmitted later by other blocks. If K_max remains, it can be applied by loading the spatial information bitstream for the next block in advance. In this case, each TS packet has an independent header, and the header may include a sync word, a length of the TS packet, and a number K of bits allocated in the packet. The present invention also embeds additional information (e.g., spatial information) in an uncompressed PCM audio signal, wherein the embedding frame size of the embedded additional information is related to the frame size S to which the additional information is applied. It may include inserting at a constant size without. The present invention also includes combining the spatial information bitstream with the downmix audio signal to form the entire bitstream. In this case, the size N of the combined spatial information bitstream may be determined by a predetermined size unit regardless of the frame size S to which spatial information is decoded and applied. It can be included in the information bitstream. The location information may include information regarding a range to which the spatial information bitstream is applied. In addition, the present invention includes determining a start position of a frame to which a spatial information bitstream is to be applied regardless of a frame to which a spatial information bitstream is combined, that is, a frame of a downmix audio signal. At this time, position information on the start position of the spatial information bitstream may be inserted in the entire bitstream.

FIG. 14A illustrates a first method for solving a time alignment problem of a spatial information bitstream embedded in a fixed size. The method of embedding a spatial alignment bitstream with a fixed size has a problem that a time alignment of a downmixed audio signal does not coincide with a frame start position of the embedded spatial information bitstream. Therefore, there is a need for a method that can solve the time axis alignment problem. The first method shown in FIG. 14 is to set a syncword 1402 (hereinafter referred to as a "data frame syncword") for the spatial information bitstream 1403. The data frame sync word 1402 may be used to identify a frame (hereinafter, referred to as a "spatial information frame") of the spatial information bitstream 1403.

For example, in the case of the TS packet 1004 and 1405, identification information 1408 in the TS packet header 1404 indicating whether a data frame sync word 1402 exists for the spatial information frame in a current packet. ) (For example, a flag). If the identification information 1408 is 1 (i.e., data frame syncword 1402 is present), positional information 1409 for downmix samples to which the spatial information frame should be aligned in the TS packet header 1404. (For example, delay information). That is, if a starting point of a new spatial information frame 1403 is present in the current TS packets 1404 and 1405, the spatial information frame 1403 is a few samples before and after the start sample of the TS packets 1404 and 1405. Location information 1409 that is in the location may be given. As described above, the location information may include information about a range to which the spatial information bitstream is applied. If the identification information 1411 is 0, the location information may not be included in the header of the TS packet. In general, since the spatial information bitstream 1403 preferably comes before the corresponding downmixed audio signal 1401, the location information 1409 may be primarily a sample value for delay. On the other hand, in order to prevent the problem that the amount of information required to express the sample value is too large because the delay is too large, a sample group unit (for example, granule unit), etc., which bundles and represents a certain sample rather than a sample unit, is defined. Thus, the location information may be expressed in units of the sample group. As described above, the TS header may include a TS sync word 1406 (hereinafter referred to as a "transmission frame sync word"), an insertion bit value 1407, and other information 1410.

FIG. 14B illustrates a second method for solving a time alignment problem of a spatial information bitstream embedded in a fixed size. For example, the second method is to match the start point of the spatial information frame 1413 with the start point of the downmixed audio signal 1412 corresponding to the start point of the TS packet. For the matching part as described above, identification information 1420 or 1422 (eg, a flag) indicating that the three starting points are aligned may be included in the header 1415 of the TS packet. FIG. 15 shows that the three pieces of identification information match in the nth frame 1412 of the downmixed audio signal. In this case, the identification information 1422 may have a value of one. If the three pieces of identification information do not match, the identification information 1420 may have a value of zero. In order to match the three starting points, a portion 1417 (fill portion) following the previous TS packet may be filled with zeros, inserted with a random signal, or replaced with the original downmixed audio signal. As described above, the TS header 1415 may include a TS syncword 1418, an insertion bit value 1418, and other information 1421.

15 illustrates a method for configuring a downmixed audio signal and a spatial information bitstream in accordance with the present invention. As shown, the spatial information bitstream 1504 may be inserted in units of a frame size of the downmixed audio signal, that is, an insertion frame size (N). For example, if the decoding frame size (S) 1503 and the insertion frame size (N) 1501 are different, the spatial information bitstream 1504 is not arbitrarily cut and fitted to the insertion frame 1501. The spatial information bitstream 1504 may be inserted into one insertion frame 1501 without being separated. In this case, the spatial information bitstream 1504 may be configured to be combined with the downmix audio signal without being embedded in the downmix audio signal. For example, the downmix audio signal may also be represented as a compressed bitstream, such that there is a downmixed audio signal bitstream 1502 in compressed form as shown, and the downmixed audio signal bitstream The spatial information bitstream 1504 may be combined into a decoding frame size at 1502. Therefore, in the present invention, the spatial information bitstream 1502 may be transmitted at a time. In addition, the present invention includes combining the spatial information bitstream 1504 into a TS bitstream 1506 in a compressed form and combining it with the downmixed audio signal bitstream 1502 in the compressed form. In this case, a TS header 1505 for the TS bitstream 1506 may be included. The TS header 1505 may include one or more of a TS syncword 1507, an insertion bit value 1508, identification information 1510, a position value 1510, or other information 1511.

16 illustrates a flowchart of a method of encoding a spatial information bitstream embedded in various sizes in a downmixed audio signal according to the present invention. First, an audio signal is downmixed from the multichannel audio signal 1601. The downmixed audio signal may comprise a mono or stereo signal. In addition, the spatial information is extracted 1603 from the multi-channel audio signal 1601, and a spatial information bitstream is generated using the spatial information (1604). If the decoding frame size S is larger than the insertion frame size N (1605), the insertion frame size N is formed to be equal to one S by grouping a plurality of N's. If the size (S) of the decoding frame is smaller than the insertion frame size (N) (1606), the insertion frame size (N) is formed so as to be equal to one N by combining a plurality of S. If N and S are equal, the insertion frame size N is formed to be equal to the decoding frame size S (1609). The spatial information bitstream formed in this manner is embedded 1610 in the downmixed audio signal and then transmits the entire bitstream including the downmixed audio signal in which the spatial information bitstream is embedded ( 1611). The present invention may include embedding information on the size of an insertion frame of the spatial information bitstream in the entire bitstream. Further, the present invention may include obtaining a K value using the downmixed audio signal and embedding the spatial information bitstream in the K bit.

17 shows a flowchart of a method of encoding a spatial information bitstream embedded with a constant size in a downmixed audio signal according to the present invention. First, an audio signal is downmixed 1702 from the multichannel audio signal 1701. The downmixed audio signal may comprise a mono or stereo signal. In addition, spatial information is extracted from the multichannel audio signal 1701 (1703), and a spatial information bitstream is generated (1704) using the spatial information. After concatenating the spatial information bitstream into a bitstream of a constant size (packet unit), for example, a transport stream (TS) (1705), the spatial information bitstream of the constant size is added to the downmixed audio signal. Embed 1706. It then transmits (1707) the entire bitstream including the downmixed audio signal in which the spatial information bitstream is embedded. Here, the present invention may include obtaining a K value using the downmixed audio signal and embedding the spatial information bitstream in the K bit.

18 illustrates a first method of embedding a spatial information bitstream in an audio signal downmixed into at least two channels in accordance with the present invention. When the downmixed audio signal is composed of at least two channels, the spatial information bitstream may be regarded as data common to the two channels. Accordingly, a method of dividing and embedding the spatial information bitstream into at least two channels is needed, and FIG. 18 illustrates a method of embedding the spatial information bitstream into only one channel of two or more channels. As shown, the spatial information bitstream is embedded in the K bits of the downmixed audio signal, only embedded in one channel and not embedded in the other. The K value may be different for each block. As described above, the K bit may correspond to a lower bit of the downmixed audio signal, but the present invention is not limited thereto. In this case, the spatial information bitstream may be put in an LSB to bit plane order or a sample order in one channel.

19 illustrates a second method of embedding a spatial information bitstream in an audio signal downmixed into at least two channels in accordance with the present invention. In the drawings, only two channels are illustrated for convenience, but the present invention is not limited thereto. As shown, the second method first embeds the spatial information bitstream into block n of one channel (here left channel), then into block n of another channel (here right channel), and then back to the original The process proceeds by embedding in block n + 1 of the channel (Left channel). Since the signal characteristics of the two channels are different, the masking limit value of each channel can be obtained separately, and the K value can be assigned to each channel differently. That is, as shown, K1 may be allocated to one channel and K2 to another channel. In addition, the K value may be different for each block. Here, the spatial information bitstream may be embedded in each channel in LSB to bit plane order or in sample order.

20 illustrates a third method for embedding a spatial information bitstream in an audio signal downmixed into at least two channels in accordance with the present invention. As shown in the drawing, the third method divides the spatial information bitstream into at least two channels and embeds them, but alternately embeds the order in two channels on a sample basis. Since the signal characteristics of the two channels are different, the masking limit value of each channel can be obtained separately, and the K value can be assigned to each channel differently. That is, as shown, K1 may be allocated to one channel and K2 to another channel. Also, the K value may be different for each block. For example, first fill the lower K1 bits of sample 1 of one channel (here, the left channel) first, and then fill the lower K2 bits of sample 1 of the other channel (here, right channel). Then, the lower K1 bits of sample 2 of the original channel (left channel) are filled again, and the lower K2 bits of sample 2 of the other channel (right channel) are filled. Numbers in blocks in the figure indicate the order of filling the spatial information bitstream. 20 shows filling from the MSB, it is also possible to fill from the LSB.

21 illustrates a fourth method for embedding a spatial information bitstream in an audio signal downmixed into at least two channels in accordance with the present invention. As shown in the drawing, the fourth method divides the spatial information bitstream into at least two channels and embeds them, and then alternates the embedding of the spatial information bitstreams into two channels in units of bits from the LSB. Since the signal characteristics of the two channels are different, the masking limit value of each channel can be obtained separately, and K (K1 and K2) values can be assigned to each channel differently. That is, as shown, K1 may be allocated to one channel and K2 to another channel. In addition, the K value may be different for each block. For example, the first 1 bit of sample 1 of one channel (here left channel) is filled first, and the lowest 1 bit of sample 1 of the other channel (here right channel) is filled first. It then fills the least significant 1 bit of sample 2 of the original channel (left channel) and again the least significant 1 bit of sample 2 of the other channel (right channel). The numbers in the blocks in the figure indicate the order of filling the spatial information bitstream.

In the third method, since the L / R channel is interleaved in units of samples when the audio signal is stored in a storage medium (for example, a stereo CD) without an auxiliary data area or transmitted in the same manner as the SPDIF, What is stored in the fourth method is advantageous for the decoder to process in the order received. In addition, the fourth method may be applied to a case in which the spatial information bitstream is rearranged and stored in bit plane units. As described above, when the spatial information bitstream is divided and embedded in two channels, it is possible to assign a K value differently to each channel. In this case, it is possible to separately transmit the K value for each channel in the bitstream. In addition, when the K value is transmitted in plural, a differential encoding method may be used when encoding the K value.

FIG. 22 illustrates a fifth method for embedding a spatial information bitstream in an audio signal downmixed into at least two channels in accordance with the present invention. As shown, the fifth method divides the spatial information bitstream into at least two channels and embeds the same, but repeatedly inserts the same value into the at least two channels. In this case, a value of the same sign may be inserted into the at least two channels, or the sign may be reversed. For example, a value of 1 may be inserted into at least two channels, or a value of 1 and -1 may be inserted alternately. The fifth method has an advantage in that transmission errors can be easily identified by comparing least significant insertion bits (eg, K bits) of at least two channels. In particular, when a mono audio signal is transmitted to a stereo medium such as a CD, since the L (left) channel and the R (right) channel of the downmixed audio signal are the same, the spatial information to be inserted is also the same to improve the robustness. can do. Here, the spatial information bitstream may be embedded in each channel in LSB to bit plane order or in sample order.

23 illustrates a sixth method for embedding a spatial information bitstream in an audio signal downmixed into at least two channels in accordance with the present invention. As shown, the sixth method relates to a method of inserting the spatial information bitstream into at least two channels when the frame of each channel is composed of a plurality of blocks (length B). As shown, the insertion bit value (ie, K value) may have a different value for each channel and block, or may have the same value. The insertion bit values (eg, K1, K2, K3 and K4) may be stored in a frame header transmitted once for the entire frame, and the frame header may be located in the LSB. In this case, the header may be inserted in units of bit planes, and the insertion of spatial information bitstream data may be performed alternately in units of samples, or alternately in units of blocks. FIG. 23 shows a case where the number of blocks in a frame is two, so that the size B of the block is N / 2. In this case, the number of bits inserted into the frame becomes (K1 + K2 + K3 + K4) * B.

24 illustrates a seventh method of embedding a spatial information bitstream in an audio signal downmixed into at least two channels in accordance with the present invention. As shown, the seventh method divides and embeds the spatial information bitstream into at least two channels, and alternately inserts the spatial information bitstream into at least two channels in units of bits from the LSB (or MSB). The method of mixing is used. The method may be performed in units of frames or in units of blocks as shown. As shown in FIG. 24, 1 to C (hatched portions) correspond to headers, and may be inserted in the LSB (or MSB) in bitplane order to facilitate the search for a data frame sync word. C + 1 or more (non-hatched portion) is a part other than the header, and can be alternately inserted in the sample unit so that data can be easily read. Insertion bit values (eg, K values) may have different values for each channel and block, or may have the same value. The insertion bit values are all included in the header so that the data to be read can be known.

25 shows a flowchart of a method for encoding a spatial information bitstream embedded in two channels of downmixed audio signals according to the present invention. First, the audio signal from the multichannel audio signal 2501 is downmixed 2502 into at least two channels. In addition, the spatial information is extracted 2503 from the multi-channel audio signal 2501, and a spatial information bitstream is generated 2504 using the spatial information. The spatial information bitstream is embedded 2505 in the downmixed audio signal into at least two channels. In this case, one or more of the four methods of embedding the spatial information bitstream into two channels may be used. It then transmits 2506 the entire bitstream including the downmixed audio signal in which the spatial information bitstream is embedded. Here, the present invention may include obtaining a K value using the downmixed audio signal and embedding the spatial information bitstream in the K bit.

FIG. 26 is a flowchart illustrating a method of decoding a spatial information bitstream embedded in a downmixed audio signal of two channels according to the present invention. First, the spatial decoder receives 2601 a bitstream including a downmixed audio signal in which a spatial information bitstream is embedded, and detects 2602 the downmixed audio signal from the bitstream. Also extracts and decodes 2603 the spatial information bitstream embedded in the downmixed audio signal of two channels from the bitstream. The downmixed audio signal is then converted to multi-channel 2604 using the spatial information obtained from the decoding. The present invention may include extracting identification information about the order in which the spatial information bitstream is embedded, and extracting and decoding the spatial information bitstream using the identification information. In addition, the present invention may include reading information on a K value from the bitstream and decoding the spatial information bitstream using the K value.

27 illustrates a first spatial encoder capable of selecting a method for transmitting a spatial information bitstream according to the present invention. As shown, first the first spatial encoder receives a multichannel audio signal 2701. N is the number of input channels. The multi-channel audio signal 2701 is downmixed by a down-mix unit 2703 to be downmixed audio signals Lo and Ro 2705. The downmix audio signal 2705 may include a mono or stereo audio signal. In the present specification, a stereo audio signal will be described as an example for convenience, but the present invention is not limited thereto. The spatial information of the multichannel audio signal, that is, the spatial parameter, is extracted from the multichannel audio signal 2701 by the spatial information extractor 2704. Alternatively, the downmixed audio signal 2705 may be generated using an externally provided downmix signal, for example, an artistic down-mix signal 2702.

The spatial information extracted by the spatial information extractor 2704 is encoded by the spatial information encoder 2707 into a spatial information bitstream. The transmission method selector 2708 may then select whether to embed the spatial information bitstream in the downmix audio signal, transmit it as a separate spatial information bitstream, or use both.

If the spatial information bitstream cannot be separately transmitted, the spatial information bitstream is directly inserted into a signal to be transmitted by the embedding unit 2706, that is, the downmix signal 2705, wherein "digital audio embedding technique (Digital Audio Embedding Technique) is used. Embeded Method) "may be used. In this case, if the "digital audio embedding technique" is used, the spatial information bitstream may be embedded in the raw PCM audio signal without sound distortion, and the audio signal in which the spatial information bitstream is embedded is a general decoder. Is indistinguishable from the original signal. That is, the output signal Lo '/ Ro' 2709 in which the spatial information bitstream is embedded may be regarded as the same signal as the input signal Lo / Ro 2705 from a general PCM decoder.

If the spatial information bitstream can be transmitted separately, the spatial information bitstream 2710 may be separately transmitted with the downmix audio signal without being embedded in the downmix audio signal. That is, in this case, the downmixed audio signal may be encoded and transmitted in a core codec bitstream, and the spatial information bitstream 2710 may be transmitted together with the core codec bitstream. For example, the spatial information bitstream may be inserted in a data track of a CD or transmitted in a general MPEG bitstream. The invention also includes embedding the spatial information bitstream in the downmix audio signal and transmitting the spatial information bitstream separately. In other words, the spatial information bitstream is transmitted in two parts. For example, a downmix audio signal in which a spatial information bitstream is embedded in one layer of a storage medium such as a compact disc (CD) is stored, and the spatial information bitstream is separately stored in another layer. The present invention includes the identification information indicating whether the spatial information bitstream is present in the entire bitstream configured as described above. When the multichannel audio signal is thus configured, not only a decoder capable of decoding the embedded spatial information bitstream, but also a decoder that cannot decode the embedded spatial information bitstream can convert the downmixed audio signal into a multichannel. You will have the advantage.

28 illustrates a second spatial encoder capable of selecting a method for transmitting a spatial information bitstream according to the present invention. As shown, the second spatial encoder is similar to the first spatial encoder. The difference is that the first spatial encoder can select whether or not to embed the spatial information bitstream into the downmix audio signal, but in the second spatial encoder, the spatial information bitstream generated by the spatial information encoding unit 2807 is embedded into It is always embedded in the downmix audio signal at 2806. The downmix audio signal 2808 in which the spatial information bitstream is embedded and the spatial information bitstream 2809 generated by the spatial information encoding unit 2807 are respectively sent to the transmission method selection unit 2810. The transmission method selector 2810 generates the entire bitstream including the downmix audio signal 2808 in which the spatial information bitstream is embedded, or the downmix audio signal 2808 and the spatial information bitstream 2809. It is possible to determine whether to generate the entire bitstream that includes all).

29 is a diagram illustrating the configuration of a bitstream for separately transmitting a spatial information bitstream in the form of an MPEG bitstream according to the present invention. As shown, (a) of FIG. 29 illustrates a case in which a separate extension bitstream 2903 independent of the core codec bitstream 2902 exists, and a spatial information bitstream in the extension bitstream 2907 is present. You can insert FIG. 29B shows an auxiliary data area composed of an auxiliary data header 2906 and an auxiliary data bitstream 2907 in the core codec bitstream 2905, and the spatial information in the auxiliary data bitstream 2907 is present. You can insert a bitstream. In this case, when configured as shown in FIG. 29A, identification information indicating whether a spatial information bitstream exists in the header 2901 is inserted, or the spatial information bitstream is included in the extension bitstream 2907. Identification information indicating whether or not may be inserted. In the case of FIG. 29B, identification information on whether the spatial information bitstream exists in the auxiliary data region may be included.

30 is a flowchart illustrating a method for transmitting a spatial information bitstream according to the present invention. First, an audio signal is downmixed 3002 from the multichannel audio signal 3001. The downmixed audio signal may comprise a mono or stereo signal. In addition, spatial information is extracted 3003 from the multi-channel audio signal 3001, and a spatial information bitstream is generated 3004 using the extracted spatial information. Next, a method of transmitting the spatial information bitstream is selected 3005. The first mode of the transmission method is to embed the spatial information bitstream in the downmix audio signal (3006) and transmit. The second mode of the transmission method is to transmit the spatial information bitstream separately. In addition, the spatial information bitstream may be transmitted together in the first mode and the second mode. The entire bitstream is then constructed and transmitted 3007 to include the spatial information bitstream and the downmix audio signal generated in each mode.

31 illustrates a first spatial decoder capable of decoding the spatial information bitstream transmitted according to the present invention. The first spatial decoder is a decoder usable when the spatial information bitstream is embedded in the downmix audio signal. First, the first spatial encoder receives a downmix audio signal 3101 in which a spatial information bitstream is embedded. The identification information extraction section 3102 then extracts identification information on how the spatial information bitstream was transmitted from the downmix audio signal 3101. The identification information may be information that a spatial information bitstream is embedded in the downmix audio signal. For example, the identification information may be a syncword. In this case, if the syncword exists in the insertion bit of the downmix audio signal, the spatial information bitstream is embedded, and the syncword exists. Otherwise, the spatial information bitstream may not be embedded. The embedded signal decoder 3103 extracts a spatial information bitstream embedded in the downmix audio signal according to the identification information. The extracted spatial information bitstream may be decoded by the spatial information decoder 3104, and spatial information may be extracted through the decoding. The extracted spatial information may be used by the multichannel generator 3105 to convert the downmix audio signal into a multichannel audio signal 3107. If the spatial information bitstream is not embedded in the downmix audio signal, the first spatial decoder can directly output 3106 the downmix audio signal with the spatial information bitstream embedded therein.

32 illustrates a second spatial decoder capable of decoding the spatial information bitstream transmitted according to the present invention. The second spatial decoder may be used when the spatial information bitstream is separately transmitted. First, the second spatial decoder receives a core codec bitstream 3201 and a spatial information bitstream 3202. The identification information extraction section 3204 then extracts identification information from the core codec bitstream 3201 or the spatial information bitstream 3202. For example, the identification indicates that there is a spatial information bitstream on the data track, indicates that there is a spatial information bitstream in the extension bitstream, or indicates that there is a spatial information bitstream in the auxiliary data area. May be information indicating that. The core codec bitstream 3201 is decoded by a core codec decoder 3203, and the spatial information bitstream is decoded by a spatial information decoder 3205. If the spatial information bitstream is on a data track, the core codec decoder 3203 may not be needed. The spatial information obtained by decoding the spatial information bitstream 3202 is used to convert the downmix audio signal obtained by decoding the core codec bitstream 3201 by the multichannel generator 3206 into a multichannel audio signal 3208. Can be.

33 illustrates a third spatial decoder capable of decoding the spatial information bitstream transmitted according to the present invention. The third spatial decoder can be used when the spatial information bitstream is embedded in the downmix audio signal and transmitted separately. The third spatial decoder receives a downmix audio signal 3301 in which the spatial information bitstream is embedded and a spatial information bitstream 3302 separately transmitted. The identification information extracting unit 3303 then extracts identification information on how the spatial information bitstream is transmitted from one or more of the core codec bitstream 3301 and the spatial information bitstream 3302. The identification information may be information indicating that the spatial information bitstream is not only embedded in the downmix audio signal but also transmitted separately together with the downmix audio signal 3301. The identification information extractor 3303 may extract the spatial information bitstream from one or more of the spatial information bitstream 3302 transmitted separately from the downmix audio signal in which the spatial information bitstream is embedded. If it is determined that it is advantageous to extract and decode spatial information from the downmix audio signal 3301, the embedded signal decoder 3304 extracts a spatial information bitstream embedded in the downmix audio signal, and then spatial information decoder 3305. Decode the spatial information bitstream extracted at If it is determined that it is advantageous to decode the spatial information bitstream 3302 separately transmitted, the spatial information bitstream 3302 directly transmitted by the spatial decoder 3305 is directly decoded. The spatial information obtained by decoding the spatial information bitstream may be used by the multichannel generator 3306 to convert the downmix audio signal into a multichannel audio signal 3308. If multichannel is not available, the downmix audio signal may be directly output 3307.

34 is a flowchart illustrating a method of decoding using a first spatial decoder according to the present invention. First, the first spatial decoder receives 3401 an entire bitstream including a downmix audio signal in which a spatial information bitstream is embedded, and extracts 3402 the downmix audio signal from the entire bitstream. It also reads 3403 from the entire bitstream identifying that a spatial information bitstream is embedded in the downmix audio signal. The spatial information bitstream is extracted 3404 from the downmix audio signal using the identification information, and the extracted spatial information bitstream is decoded 3405. The spatial information bitstream is then decoded to extract spatial information (3406), and the downmixed audio signal is converted to multichannel using the extracted spatial information (3407).

35 is a flowchart illustrating a method of decoding using a second spatial decoder according to the present invention. First, the second spatial decoder receives 3501 an entire bitstream including a core codec bitstream and a spatial information bitstream for a downmix audio signal. Here, the spatial information bitstream is not embedded in the downmix audio signal, but separately transmitted together with the core codec bitstream. The core codec bitstream is then decoded 3502 from the entire bitstream to extract 3504 the downmix audio signal. In addition, identification information indicating that the spatial information bitstream is not embedded in the downmix audio signal is transmitted separately from the entire bitstream (3503). The spatial information is decoded using the identification information (3505) to extract spatial information (3506). The downmixed audio signal is then converted into multichannels using the extracted spatial information (3507).

36 is a flowchart illustrating a method of decoding using a third spatial decoder according to the present invention. First, the third spatial decoder receives 3601 an entire bitstream including a core codec bitstream and a separate spatial information bitstream for a downmix audio signal in which the spatial information bitstream is embedded. A downmix audio signal is then extracted 3603 from the entire bitstream. Further, 3602 extracts identification information indicating that the spatial information bitstream is not only embedded in the downmix audio signal but also transmitted separately from the entire bitstream. Then, in accordance with the identification information, a method of decoding the spatial information bitstream is selected 3604. The decoding method includes a first mode for decoding the spatial information bitstream embedded in the downmix audio signal, and a second mode for decoding the spatial information bitstream transmitted separately. If it is determined that decoding in the first mode is advantageous, the spatial information bitstream is extracted 3605 from the core codec bitstream, and the extracted spatial information bitstream is decoded 3606. If it is determined that the second mode is advantageous, the separately transmitted spatial information bitstream is decoded (3606). Next, the spatial information is extracted 3602 through the decoding, and the downmixed audio signal is converted into a multichannel using the extracted spatial information (3608).

Although the present invention has been described in detail with reference to some embodiments, the above embodiments are presented for the purpose of understanding the present invention, and the scope of the present invention is not limited to the above embodiments. Those skilled in the art will understand that various modifications are possible without departing from the scope of the technical idea of the present invention, and the scope of the present invention should be interpreted by the appended claims.

As described above, in coding a multichannel audio signal according to the present invention, a spatial information bitstream is embedded in a downmixed audio signal and sent, a spatial information bitstream is sent separately, or a spatial information bitstream. Provides an encoding method that not only embeds a downmix audio signal, but also selects a method of sending it separately to various types of transmission media such as a medium for transmitting spatial information separately and a medium for transmitting spatial information separately. There is an effect that can transmit a multi-channel audio signal.

In addition, the present invention provides spatial information bits provided according to respective schemes when the spatial information bitstream is embedded in the downmix audio signal, when sent separately, or when not only embedded in the downmix audio signal but also transmitted separately. By providing a method of decoding a stream, the spatial information bitstream provided in various ways can be used.

Claims (28)

A method of encoding a multichannel audio signal, (a) downmixing the multichannel audio signal and extracting spatial information from the multichannel audio signal; (b) generating a spatial information bitstream using the spatial information; (c) selecting a method of transmitting the generated spatial information bitstream; And (d) generating, according to the selected method, an entire bitstream comprising the spatial information bitstream and the downmix audio signal. The method of claim 1, The transmitting method is characterized in that for embedding the spatial information bitstream in the downmix audio signal and transmits. The method of claim 2, And said spatial information bitstream is embedded within an insertion bit of said downmix audio signal. The method of claim 3, wherein And the insertion bit is obtained by using a masking threshold of the downmixed audio signal. The method of claim 1, The transmitting method is characterized in that for transmitting the spatial information bitstream separately from the downmix audio signal, the multi-channel audio signal encoding method. The method of claim 1, The transmitting method is characterized in that for embedding the spatial information bitstream in the downmix audio signal, and transmits separately from the downmixed audio signal. The method of claim 1, And the identification information on the transmission method is included in the entire bitstream. A method of encoding a multichannel audio signal, (a) downmixing the multichannel audio signal and extracting spatial information from the multichannel audio signal; (b) generating a spatial information bitstream using the spatial information; (c) embedding the generated spatial information bitstream into the downmix audio signal; And (d) generating an entire bitstream such that the spatial information bitstream includes an embedded downmix audio signal, and determining whether to include the spatial information bitstream separately within the entire bitstream; A method for encoding a multichannel audio signal. The method of claim 8, Step (c) is, And embedding said spatial information bitstream into an embedded bit of said downmix audio signal. The method of claim 8, In step (d), And configuring the entire bitstream such that the spatial information bitstream is not included separately in the entire bitstream. The method of claim 8, In step (d), And constructing the entire bitstream such that the spatial information bitstream is separately included in the entire bitstream. The method of claim 8, And the identification information on the transmission method is included in the entire bitstream. In the method of decoding into a multi-channel audio signal, (a) receiving the entire bitstream including the downmix audio signal in which the spatial information bitstream is embedded; (b) extracting a spatial information bitstream embedded in the downmix audio signal; And and (c) converting the downmix audio signal into a multichannel audio signal using spatial information obtained by decoding the spatial information bitstream. The method of claim 13, The decoding method, And before step (b), extracting identification information indicating that the spatial information bitstream is embedded in the downmix audio signal from the entire bitstream. How to. In the method of decoding into a multi-channel audio signal, (a) receiving an entire bitstream comprising a spatial information bitstream and a downmix audio signal; (b) extracting the spatial information bitstream transmitted separately from the downmix audio signal from the entire bitstream; And and (c) converting the downmix audio signal into a multichannel audio signal using spatial information obtained by decoding the spatial information bitstream. The method of claim 15, And said spatial information bitstream is stored and transmitted in a data track of a compact disc. The method of claim 15, And said spatial information bitstream is stored and transmitted in an extension bitstream. The method of claim 15, And said spatial information bitstream is stored and transmitted in an auxiliary data region within a core codec bitstream. The method of claim 15, The decoding method, And before the step (b), extracting identification information indicating that the spatial information bitstream is transmitted separately from the downmix audio signal from the entire bitstream. How to decode. In the method of decoding into a multi-channel audio signal, (a) receiving an entire bitstream comprising a downmix audio signal having a spatial information bitstream embedded therein and a spatial information bitstream transmitted separately; (b) extracting a spatial information bitstream from the downmix audio signal, decoding the extracted spatial information bitstream, or decoding the separately transmitted spatial information bitstream; And and (c) converting the downmix audio signal into a multichannel audio signal using spatial information obtained by decoding the spatial information bitstream. The method of claim 20, The decoding method, Prior to step (b), extracting identification information indicating that the spatial information bitstream is embedded and transmitted in the downmix audio signal and transmitted separately from the downmix audio signal from the entire bitstream. And decoding a multichannel audio signal. A method of encoding a multichannel audio signal, (a) downmixing the multichannel audio signal and extracting spatial information from the multichannel audio signal; (b) generating a spatial information bitstream for each frame using the spatial information; And (c) Composing the entire bitstream by combining the spatial information bitstream and the downmixed audio signal, the frame size (N) of the spatial information bitstream is a frame size (S) unit to which spatial information is decoded and applied. And combining with the downmix audio signal. The method of claim 22, And position information on an application range of the spatial information bitstream is inserted into a header of the spatial information bitstream. The method of claim 22, And a syncword for a start position of the spatial information bitstream is inserted in a header for the spatial information bitstream. In the method of decoding into a multi-channel audio signal, (a) receiving an entire bitstream comprising a downmixed audio signal coupled with a spatial information bitstream; And (b) extracting and decoding the spatial information bitstream combined with the downmixed audio signal on a frame size (S) basis in which spatial information is decoded and applied from the entire bitstream. Decoding into a multichannel audio signal. The method of claim 25, In step (b), And converting the downmixed audio signal into a multichannel audio signal using the spatial information obtained by decoding the spatial information. The method of claim 25, The decoding method And before the step (b), reading out location information to which the spatial information bitstream is to be applied from the entire bitstream. In the method of generating an audio signal, The audio signal is generated to include a downmixed audio signal and a spatial information bitstream, The spatial information bitstream is combined with the downmixed audio signal to form an entire bitstream, and the spatial information bitstream is generated to be combined with the downmix audio signal by a frame size (S) applied by decoding the spatial information bitstream. An audio signal generation method.

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