KR100944542B1 - Method and Apparatus for Coding and Decoding using Predictive Bit-Precision - Google Patents

Abstract

Disclosed are a method and apparatus for encoding / decoding using prediction decision bits. An encoding apparatus according to an embodiment of the present invention includes a first decision bit calculator for calculating initial decision bits for symbols to be encoded, a second decision bit calculator for calculating prediction decision bits for symbols to be encoded, and And an encoder that encodes input data by using an initial decision bit or the prediction decision bit. According to the present invention, the compression efficiency is improved by encoding / decoding the image data using the prediction decision bit calculated based on the neighboring macroblock.

Initial decision bit, prediction decision bit, macroblock, encoding, decoding

Description

Method and Apparatus for Encoding / Decoding Using Predictive Decision Bits {Method and Apparatus for Coding and Decoding using Predictive Bit-Precision}

The present invention relates to an apparatus for encoding and decoding image data (hereinafter referred to as " decoding / decoding "), and more particularly, to an encoding / decoding method and apparatus for increasing compression efficiency of image data. It is about.

 As the amount of data transmission per second over the Internet increases, the amount of multimedia data such as moving pictures and photos is increasing compared to the past when simple text data is being transmitted. Accordingly, the demand for image compression technology is also increasing.

In order to compress an image, an entropy coding process of transforming a bit string representing a symbol included in data into another form is required. Entropy coding methods include Huffman coding and Arithmetic coding. In particular, Huffman coding is used in many video compression codecs because it guarantees an adequate level of compression efficiency and decoding complexity. Arithmetic geometry coding is used in fields requiring high compression efficiency because of its high decoding complexity but relatively high compression efficiency.

Recently, with the advent of various mobile media devices using limited power and composed of low-performance hardware, an entropy coding method with low decoding complexity is required. However, there is a problem in that research on a method of reducing decoding complexity is insufficient compared to a method for increasing the compression efficiency of an image.

On the other hand, as a method for reducing decoding complexity, an entropy coding scheme using bit precision has recently been proposed. However, the coding scheme has a problem in that compression efficiency is lowered by additionally inserting one decision bit per VOP or macroblock into the bitstream.

The present invention provides a method and apparatus for encoding / decoding using prediction decision bits that can improve compression efficiency by encoding / decoding video data using prediction decision bits calculated based on neighboring macroblocks. have.

In addition, the present invention encodes / decodes the image data by using the prediction decision bit calculated for the symbols of the neighboring macroblocks together with the initial decision bit calculated for the corresponding symbols, thereby increasing compression efficiency and reducing decoding complexity. Another object of the present invention is to provide a method and apparatus for encoding / decoding using predictive decision bits.

According to an aspect of the present invention, a first decision bit calculator for calculating an initial decision bit for the symbols to be encoded; A second decision bit calculator configured to calculate a prediction decision bit for symbols to be encoded; And an encoder which encodes input data using the initial decision bit or the prediction decision bit.

According to another aspect of the present invention, there is provided a method comprising: (a) calculating an initial decision bit for symbols to be encoded; (b) calculating a prediction decision bit for symbols to be encoded; And (c) encoding input data using the initial decision bit or the prediction decision bit.

According to another aspect of the present invention, a program of instructions that can be executed by an encoding apparatus is tangibly implemented to perform an encoding method of the encoding apparatus, and is recorded on a recording medium that records a program that can be read by the encoding apparatus. A method comprising: (a) calculating an initial decision bit for symbols to be encoded; (b) calculating a prediction decision bit for symbols to be encoded; And (c) a recording medium having a program recorded thereon which performs the step of encoding input data using the initial decision bit or the prediction decision bit.

According to another aspect of the invention, the first decision bit extraction unit for extracting the initial determination bit from the input data; A second decision bit calculator for calculating a prediction decision bit for data to be decoded; There is provided a decoding apparatus including a decoder which decodes input data by using the initial decision bit or the prediction decision bit.

According to another aspect of the present invention, there is provided a method comprising: (a) extracting an initial decision bit from input data; (b) calculating prediction decision bits for the data to be decoded; and (c) decoding input data using the initial decision bit or the prediction decision bit.

According to another aspect of the present invention, a program of instructions that can be executed by a decoding apparatus for performing a decoding method of the decoding apparatus is tangibly embodied, and on a recording medium recording a program that can be read by the decoding apparatus. A method comprising: (a) extracting initial decision bits from input data; (b) calculating prediction decision bits for the data to be decoded; (c) There is provided a recording medium having a program recorded thereon that performs a step of decoding input data using the initial decision bit or the prediction decision bit.

According to the present invention, the compression efficiency is improved by encoding / decoding the image data by using the prediction decision bit calculated based on the neighboring macroblock.

According to the present invention, by encoding / decoding video data by using a prediction decision bit calculated based on a neighboring macro block together with an initial decision bit calculated for the corresponding symbols, compression efficiency can be increased and decoding complexity can be reduced. It works.

As the invention allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the written description. However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all transformations, equivalents, and substitutes included in the spirit and scope of the present invention. In the following description of the present invention, if it is determined that the detailed description of the related known technology may obscure the gist of the present invention, the detailed description thereof will be omitted.

Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

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

The present invention relates to an encoding technique using decision bits. More specifically, the symbol is encoded using an initial decision bit or a prediction decision bit. First, a concept of an encoding scheme using decision bits according to the present invention will be described, and then initial decision bits and prediction decision bits will be described.

The encoding method according to the present invention specifies a decision bit for symbols of input data. At this time, the symbol is each word unit constituting the input data. The decision bit is a value representing the length of a unit bit string for encoding symbols using bits, which are binary codes. That is, when the decision bit is n, the input symbols are encoded by being represented in binary using n unit bit strings. For example, assume that the input symbols are {2, 1, 0, 4, 5, 3} and the decision bit is 2. A value that can be represented by two bits (ie, a unit bit string) may represent a value from 0 to 3. However, if the symbol is larger than 3, it is impossible to express it with two bits, and thus additionally allocate two more bits to represent a value larger than three. More detailed description is as follows. Symbol 2 is represented by '10' when the value is binarized as it is, symbol '1' is represented by '01' when binarized, and symbol '0' is represented by '00' when binarized. However, since the symbol '4' is larger than 3, which is the maximum value represented by 2 bits, the symbol '4' cannot be represented by only 2 bits of the unit bit string. Therefore, the maximum value that can be represented by the first two bit values is expressed as '11', and the insufficient value 1 is expressed as the additional unit bit string '01' to connect two results. That is, the symbol '4' may be represented by '1101'. Similarly to symbol 4, symbol 5 is represented by '1110' by combining the maximum value 3 and the surplus value 2 using 2 bits. In the case of symbol 3, it can be represented by 2 bits, but in this case, it is indistinguishable from the case of expressing a value greater than 3, and thus additional 2 bits are added to represent '1100' when the surplus value is 0. do.

If the above-described encoding method using the decision bit is applied to the case where the data symbol is 0 to 9, it can be expressed as shown in Table 1 below.

 symbol Decision bit 1 Decision bit 2 Decision bit 3 Decision bit 4 Decision bit 5 0 0 00 000 0000 00000 One 10 01 001 0001 00001 2 100 10 010 0010 00010 3 1000 1100 011 0011 00011 4 10000 1101 100 0100 00100 5 100000 1110 101 0101 00101 6 1000000 111100 110 0110 00110 7 10000000 111101 111000 0111 00111 8 100000000 111110 111001 1000 01000 9 1000000000 11111100 111010 1001 01001

As shown in Table 1, the bit string in which the symbol is encoded varies according to the decision bit. Therefore, it is necessary to select which one of several types of decision bits to encode before performing the encoding process, and the encoding compression rate varies according to the selected decision bits.

According to the present invention, decision bits to be used for encoding are selected using two methods. The first method selects the decision bits to be encoded from the candidate decision bits using the values of the target symbols, and the second method uses the values of the surrounding symbols of the target symbols to determine the decision bits to be encoded from the candidate decision bits. This is how you decide. The decision bits selected by the first scheme are called initial decision bits, and the decision bits selected by the second scheme are called predictive decision bits. That is, the initial decision bit is a decision bit calculated using target symbols to which the initial decision bit is to be applied, while the prediction decision bit is a decision bit calculated using peripheral symbols of the target symbols.

A method for calculating an initial decision bit according to the present invention will be described in detail as follows. First, symbols to be encoded in a predetermined unit (VOP, macro block, or block unit) are encoded by using candidate decision bits in a predetermined range (1 to n), and then a decision bit having the best compression efficiency is selected as a decision bit to be encoded. do. Here, the final predetermined decision bit is called an initial decision bit. For example, assuming that encoding bits having a value of 1 to 3 are encoded in a VOP unit, all symbols included in the corresponding VOP are encoded using 1 to 3 candidate decision bits. At this time, if the capacity of the VOP encoded using the candidate decision bits 1 to 3 is 3, 2, and 1 [Mbyte], respectively, decision bit 3 is finally selected as the initial decision bit of the corresponding VOP. According to the present invention according to the above-described method it is possible to select and use the decision bit having the highest compression ratio.

1 is a diagram for describing a method of calculating prediction determination bits according to an embodiment of the present invention.

Referring to FIG. 1, a prediction decision bit is a decision bit calculated using symbols belonging to an upper macroblock and / or a left macroblock of a macroblock to be currently encoded (hereinafter referred to as a 'target macroblock'). For example, X in FIG. 1 is a target macroblock, A is an upper macroblock, and B is a left macroblock. The prediction decision bit of the target macroblock X is a decision bit calculated for symbols included in A and B. The method of selecting the decision bit is as described above with reference to Table 1. That is, symbols included in A and B are encoded using decision bits 1 to n in a predetermined range, and the decision bits of the smallest encoded capacity are calculated as the prediction decision bits of the target macroblock X.

In this case, when only one of the upper macro block or the left macro block exists (when the target macro block is located at the top of the VOP or at the leftmost side), the symbols of the existing upper macro block or the left macro block are targeted. The prediction decision bit may be calculated. If neither the upper macro block nor the left macro block exists (that is, the target macro block is located at the top left), the prediction decision bit cannot be calculated. In this case, encoding may be performed using an initial decision bit calculated for a symbol belonging to the corresponding VOP.

2 is a block diagram of an encoding apparatus using prediction decision bits according to an embodiment of the present invention.

Referring to FIG. 2, an encoding apparatus using prediction determination bits according to an embodiment of the present invention may include an input unit 210, a prediction determination bit calculator 220, an initial determination bit calculator 230, and an encoder 240. It includes.

The input unit 210 receives input data from the outside and extracts and outputs symbols to be encoded. At this time, the input unit 210 divides the extracted symbols into a VOP unit and a macroblock unit (or a block unit of a predetermined size), together with the classification information, the prediction decision bit calculator 220 and the initial decision bit calculator 230. ) And to the encoder 240. In this case, the input data may include one of data corresponding to pixels, mcbpc, cbpy, mv (motion vector) -x, mv-y, DCT-luma, and DCT-chroma. Mcbpc, cbpy, motion vector (mv) -x, mv-y, DCT-luma and DCT-chroma are data used in the encoding / decoding process according to the MPEG standard. Since this is obvious to those skilled in the art, a detailed description thereof will be omitted.

The prediction decision bit calculator 220 divides the received symbols into macroblock units, calculates a prediction decision bit of the target macroblock, and outputs the prediction decision bit to the encoder 240. The detailed calculation process of the prediction decision bit is as described above and will be omitted. However, when both the upper macroblock and the left macroblock of the target macroblock do not exist (that is, when the target macroblock is located at the top left), the prediction decision bit is calculated as '0' and output. Also, the prediction decision bit is calculated as '0' even when the upper macro block and the left macro block are skipped macro blocks. Information indicating whether the upper macro block and the left macro block are skipped macro blocks may be included in the input data or may be separately input from the outside. The skipped macroblock refers to a macroblock that has been skipped in the encoding process, which is obvious to those skilled in the art, and thus detailed description thereof will be omitted.

The initial decision bit calculator 230 divides the received symbols into VOP units, calculates an initial decision bit, and outputs the initial decision bit to the encoder 240. The detailed calculation process of the initial decision bit is as described above.

The encoder 240 encodes the symbol by using one of the prediction decision bit or the initial decision bit received from the prediction decision bit calculator 220 and / or the decision bit calculator 230.

The encoding process of the encoder 240 will now be described in detail.

First, the encoder 240 inserts an initial decision bit of the VOP into the bitstream.

Subsequently, the encoder 240 determines whether the prediction decision bits of the macroblocks included in the VOP are '0'.

As a result of the determination, if the prediction decision bit is 0, the symbols of the target macroblock are encoded using the initial decision bit of the corresponding VOP.

If the prediction decision bit is not 0, the encoding unit 240 encodes the symbols of the target macroblock using the prediction decision bit. Subsequently, the encoder 240 inserts a bit string obtained by encoding the symbols into the bitstream.

3 is a flowchart illustrating an encoding process using prediction decision bits according to an embodiment of the present invention.

First, an initial decision bit of the VOP is calculated (305). In this case, the symbols included in the VOP may be a value representing one of mcbpc, cbpy, mv (motion vector) -x, mv-y, DCT-luma, and DCT-chroma. Since the method for calculating the initial decision bit has been described above with reference to Table 1, a detailed description thereof will be omitted.

Then, the calculated initial decision bit is inserted into the bitstream (310).

Subsequently, it is determined whether the target macroblock is located at the top left corner or the skipped macroblock is skipped (left and right).

As a result of the determination (315), if the macro block is the upper left corner part or the skipped macro block, the prediction decision bit is calculated as '0' (320).

On the other hand, if the macroblock is not the upper left corner part and the macroblock skipped by the upper and left macroblocks, the prediction decision bit is calculated using the left or upper macroblock (325). .

Next, it is determined whether the prediction decision bit is 0 (330).

As a result of the determination 330, when the prediction determination bit is 0, the symbols of the target macroblock are encoded using the initial determination bit of the corresponding VOP (335).

If the prediction decision bit is not 0, the determination result 330 encodes the symbols of the target macroblock using the prediction decision bit (340).

Subsequently, the coded bit string is inserted into the bit stream (345).

Although the above-described encoding process has been described as encoding symbols included in one macro block for clarity, the encoding apparatus repeats steps 315 to 340 until all the symbols of the frame or the VOP are encoded. Can be done.

4 is a block diagram of a decoding apparatus using prediction decision bits according to an embodiment of the present invention.

Referring to FIG. 4, a decoding apparatus using prediction decision bits according to an embodiment of the present invention may include an input unit 410, a prediction decision bit calculator 420, a decoder 430, and an initial decision bit extractor 440. It includes.

The input unit 410 receives data encoded using an initial decision bit and / or a prediction decision bit from the outside. Subsequently, the input unit 410 outputs the input coded input data to the initial decision bit calculator 440 and the decoder 430.

The initial decision bit extractor 440 extracts an initial decision bit inserted in the encoded bitstream and outputs the initial decision bit to the decoder 430.

The prediction decision bit calculator 420 receives a signal for requesting the prediction decision bit of the target macroblock and a symbol from which the previous macroblock is decoded from the decoder 430. In this case, the prediction decision bit calculator 420 may store the decoded symbol received from the decoder 430 until the end of the decoding process of the corresponding VOP. Subsequently, the prediction decision bit calculator 420 calculates the prediction decision bit with reference to the decoded symbols of the upper and left macroblocks of the target macroblock and outputs the prediction decision bit to the decoder 430. Since the method of calculating the prediction decision bit has been described above with reference to FIG. 1, a detailed description thereof will be omitted.

The decoder 430 decodes the encoded data input from the input unit 410 using an initial decision bit or a prediction decision bit.

The processing of the decoder 430 will now be described in more detail. The decoder 430 extracts a bit string by a length corresponding to the value of the initial determination bit from the encoded data. Assuming that the initial decision bit is 3, for example, the decoder 430 extracts 3 bits from the encoded data to decode the uppermost left macroblock of the VOP. Of course, if the extracted 3 bits are '111', the decoder 430 further extracts 3 bits. In addition, it is obvious that the decoder 430 sequentially extracts each bit from the encoded data. Subsequently, the decoder 430 decodes the extracted bits into symbols. For example, assuming that '111001' is extracted, the decoder 430 decodes the extracted 6 bits into a symbol '8' as illustrated in Table 1. The decoder 430 repeats the above-described extraction and reconstruction process until all the symbols of the uppermost left macroblock of the VOP are decoded. The decoder 430 decodes all symbols of the target macroblock and outputs the symbols to the prediction decision bit calculator 420.

Subsequently, the decoder 430 sets the right macroblock of the macroblock decoded in the above-described process as the target macroblock. The decoder 430 determines whether the upper and left macro blocks are skipped macro blocks. In this case, information indicating whether the upper and left macroblocks are skipped macroblocks may be included in the encoded data or separately input from the outside. When the upper and left macro blocks are the skipped macro blocks, the decoder 430 decodes the bit strings encoded using the initial decision bits into symbols of the target macro block. The process of decoding by using the initial decision bit has been described above in the process of decoding the uppermost left macro block of the VOP. If the target macroblock is not the skipped macroblock, the decoder 430 outputs a signal for requesting the prediction decision bit of the target macroblock to the prediction decision bit calculator 420.

Subsequently, the decoder 430 receives the prediction decision bit of the target macroblock from the prediction decision bit calculator 420. Subsequently, the decoder 430 extracts an encoded bit string from the bitstream, and decodes the encoded bit string using the prediction determination bits into symbols of the target macroblock. Decoding using the prediction decision bit is the same as decoding using the initial decision bit, and thus description thereof will be omitted. In this case, when the calculated prediction decision bit is 0, the decoder 430 performs decoding using the initial decision bit.

Subsequently, the decoder 430 sets the right macroblock of the previously decoded macroblock as the target macroblock. If the right macro block no longer exists, the macro block located at the leftmost of the lower macro blocks is set as the target macro block. Since the decoding of the symbols of the macroblock is the same as the decoding process described above, a description thereof will be omitted. Subsequently, the decoder 430 outputs the symbol data of the decoded macroblock to the prediction decision bit calculator 420. When the decoding unit 430 completes decoding all the macroblocks in the VOP, the decoding process of the corresponding VOP ends.

5 is a flowchart illustrating a decoding process using prediction decision bits according to an embodiment of the present invention.

First, an initial decision bit is extracted from the input encoded data (505).

Subsequently, it is determined whether the target macroblock is located at the uppermost left side or whether the upper and left macroblocks are skipped macro blocks (510).

As a result of the determination (510), when the target macroblock is located at the top left or is a macroblock in which the upper and left macroblocks are skipped, the encoded data is decoded using the initial decision bits (525).

On the other hand, in the determination result 510, when the target macroblock is not located at the top left and the upper and left macroblocks are not skipped macroblocks, the target macroblocks are decoded using the symbols of the upper and / or left macroblocks that are already decoded. The prediction decision bit of the macro block is calculated (515).

Next, it is determined whether the calculated prediction decision bit is '0' (520).

As a result of the determination 520, when the prediction determination bit is '0', the encoded data is decoded using the initial determination bit (525).

If the prediction decision bit is not '0', the encoded bit stream is extracted from the bitstream and the encoded bit stream is decoded using the prediction decision bit (530).

Although the above-described decoding process has been described as encoding symbols included in one macro block for clarity, the decoding apparatus performs steps 510 to 530 until each symbol of the corresponding frame or VOP is encoded. You can iterate over macro blocks.

Although the above has been described with reference to a preferred embodiment of the present invention, those skilled in the art to which the present invention pertains without departing from the spirit and scope of the present invention as set forth in the claims below It will be appreciated that modifications and variations can be made.

1 is a view for explaining a method of calculating prediction determination bits according to an embodiment of the present invention.

2 is a block diagram of an encoding apparatus using prediction decision bits according to an embodiment of the present invention.

3 is a flowchart illustrating an encoding process using prediction decision bits according to an embodiment of the present invention.

4 is a block diagram of a decoding apparatus using prediction decision bits according to an embodiment of the present invention.

5 is a flowchart illustrating a decoding process using prediction decision bits according to an embodiment of the present invention.

Claims (40)

A first decision bit calculator for calculating an initial decision bit for symbols to be encoded; A second decision bit calculator configured to calculate a prediction decision bit for symbols to be encoded; And An encoder which encodes input data using the initial decision bit or the prediction decision bit, The initial decision bit is a decision bit calculated using target symbols to which the initial decision bit is to be applied. The prediction decision bit is a decision bit calculated in units of blocks having a predetermined size and calculated using symbols of neighboring blocks of the target block. And the determination bit is a value representing a length of a unit bit string for encoding the symbols. delete According to claim 1, The second decision bit calculator is, And a prediction decision bit for the target block using symbols included in at least one of the upper and left blocks of the target block. The method of claim 1, The second decision bit calculation unit, The encoding device characterized in that the decision bit having the highest compression efficiency is selected as the prediction decision bit among the predetermined candidate decision bits (1 to n). The method of claim 1, The second decision bit calculation unit, And encoding the prediction decision bits in macroblock units. The method of claim 1, The encoder, And encoding symbols by a macroblock unit using the prediction decision bit or the initial decision bit. The method of claim 1, The encoder, And encoding when the target block is located at the top left side or is a skipped macro block in which upper and left blocks of the target block are skipped. According to claim 1, The encoder, Encoding according to the value of the prediction decision bit using either the initial decision bit or the prediction decision bit. The method of claim 1, The encoder, And when the prediction decision bit is '0', encoding using the initial decision bit. The method of claim 1, The encoder, And inserting the initial decision bit into an encoded bit stream. The method of claim 1, The first decision bit calculator is, And encoding the initial decision bit in a VOP unit. The method of claim 1, The first decision bit calculator is, Selecting a decision bit having the highest compression efficiency as the initial decision bit among predetermined candidate decision bits 1 to n; An encoding device, characterized in that. (a) calculating an initial decision bit for symbols to be encoded; (b) calculating a prediction decision bit for symbols to be encoded; And (c) encoding input data using the initial decision bit or the prediction decision bit, The initial decision bit is a decision bit calculated using target symbols to which the initial decision bit is to be applied. The prediction decision bit is a decision bit calculated in units of blocks having a predetermined size and calculated using symbols of neighboring blocks of the target block. And the determination bit is a value representing a length of a unit bit string for encoding the symbols. delete The method of claim 13, In step (b), And a prediction decision bit for the target block is calculated using symbols included in at least one of the upper and left blocks of the target block. The method of claim 13, In step (b), A coding method, characterized in that among the predetermined candidate decision bits (1 to n), a decision bit having the highest compression efficiency is selected as a prediction decision bit. The method of claim 13, In step (b), And encoding the prediction decision bits in macroblock units. The method of claim 13, In step (c), And encoding symbols in macroblock units using the prediction decision bit or the initial decision bit. The method of claim 13, In step (c), And encoding using the initial decision bit when the target block is located at the top left side or a macroblock in which upper and left blocks of the target block are skipped. The method of claim 13, Step (C) is Encoding according to the value of the prediction decision bit using either the initial decision bit or the prediction decision bit. The method of claim 13, In step (c), And if the prediction decision bit is '0', encoding using the initial decision bit. The method of claim 13, In step (c), Inserting the initial decision bits into an encoded bit stream Encoding method further comprising. The method of claim 13, In step (a), And encoding the initial decision bit in a VOP unit. The method of claim 13, In step (a), Selecting a decision bit having the highest compression efficiency as the initial decision bit among predetermined candidate decision bits 1 to n; Encoding method characterized in that. In the recording medium in which a program of instructions that can be executed by an encoding apparatus is tangibly embodied to perform an encoding method of the encoding apparatus. (a) calculating an initial decision bit for symbols to be encoded; (b) calculating a prediction decision bit for symbols to be encoded; And (c) a recording medium having a program recorded thereon which performs encoding of input data using the initial decision bit or the prediction decision bit. A first decision bit extractor for extracting an initial decision bit from input data; A second decision bit calculator for calculating a prediction decision bit for data to be decoded; And a decoder which decodes input data using the initial decision bit or the prediction decision bit. The method of claim 26, The initial decision bit is a decision bit included in the input data, The prediction decision bit is a decision bit calculated in units of blocks having a predetermined size and calculated using decoded data of neighboring blocks of the target block. And the determination bit is a value indicating a length of a unit bit string used for encoding data. The method of claim 26, The second decision bit calculation unit, And a prediction decision bit for the target block is calculated by using a complex value of symbols included in at least one of the upper and left blocks of the target block. The method of claim 26, The second decision bit calculation unit, A decoding device, characterized in that among the predetermined candidate decision bits (1 to n), a decision bit having the highest compression efficiency is selected as a prediction decision bit. The method of claim 26, The second decision bit calculation unit, And decoding the prediction decision bits in macroblock units. The method of claim 26, The decoder decodes a target block by selectively using the initial decision bit and the prediction decision bit in units of blocks of a predetermined size, And decoding the block by using the initial decision bit when the target block is located at the uppermost left side or when the upper and left blocks of the target block are skipped macro blocks. The method of claim 26, And if the prediction determination bit of the target block is '0', the decoding unit decodes using the initial determination bit. (a) extracting an initial decision bit from input data; (b) calculating prediction decision bits for the data to be decoded; (c) decoding input data using the initial decision bit or the prediction decision bit Decryption method comprising a. The method of claim 33, wherein The initial decision bit is a decision bit included in the input data, The prediction decision bit is a decision bit calculated in units of blocks having a predetermined size and calculated using decoded data of neighboring blocks of the target block. And said decision bit is a value representing the length of a unit bit string used for encoding data. The method of claim 33, wherein In step (b), And a prediction decision bit for the target block is calculated by using the decoded values of symbols included in at least one of the upper and left blocks of the target block. The method of claim 33, wherein In step (b), A decoding method, characterized in that the decision bit having the highest compression efficiency is selected as the prediction decision bit among the predetermined candidate decision bits (1 to n). The method of claim 33, wherein In step (b), And calculating the prediction decision bits in macroblock units. The method of claim 33, wherein In step (c), And decoding the block by using the initial decision bit when the target block is located at the top left side or a skipped macro block in which the upper and left blocks of the target block are skipped. The method of claim 33, wherein In step (c), And if the prediction decision bit is '0', decoding using the initial decision bit. In the recording medium on which a program of instructions that can be executed by a decoding apparatus to perform a decoding method of the decoding apparatus is tangibly implemented, and which records a program that can be read by the decoding apparatus, (a) extracting an initial decision bit from input data; (b) calculating prediction decision bits for the data to be decoded; (c) a recording medium having a program recorded thereon that performs decoding the input data using the initial decision bit or the prediction decision bit.

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