KR20190122514A - A method and an apparatus for processing a video signal using cost measurement for sign data hiding - Google Patents

Abstract

The present invention relates to a method and apparatus for processing a video signal and, more specifically, to a method and apparatus for processing a video signal to encode or decode a video signal. An objective of the present invention is to improve the coding efficiency of a video signal.

Description

A video signal processing method and apparatus using Hiding detection method for data sign information {A METHOD AND AN APPARATUS FOR PROCESSING A VIDEO SIGNAL USING COST MEASUREMENT FOR SIGN DATA HIDING}

The present invention relates to a method and apparatus for processing a video signal, and more particularly, to a video signal processing method and apparatus for encoding or decoding a video signal.

Compression coding refers to a series of signal processing techniques for transmitting digitized information through a communication line or for storing in a form suitable for a storage medium. The object of compression encoding includes objects such as voice, video, text, and the like. In particular, a technique of performing compression encoding on an image is called video image compression. Compression coding on a video signal is performed by removing redundant information in consideration of spatial correlation, temporal correlation, and stochastic correlation. However, with the recent development of various media and data transmission media, there is a need for a method and apparatus for processing video signals with higher efficiency.

An object of the present invention is to improve the coding efficiency of a video signal.

In order to solve the above problems, the image decoding method according to an embodiment of the present invention adaptively determines whether the weighted prediction method is applied and related setting values in the process of using the unidirectional mode or the bidirectional mode for inter prediction. And applying the reference block to generate a prediction block for the block to be currently predicted.

According to an embodiment of the present invention, coding efficiency of a video signal may be increased.

1 is a schematic block diagram of a video signal encoder apparatus according to an embodiment of the present invention.
2 is a schematic block diagram of a video signal decoder device according to an embodiment of the present invention;
3 illustrates an embodiment of the present invention for dividing a coding unit.
FIG. 4 illustrates an embodiment of a method for hierarchically representing the partition structure of FIG. 3. FIG.
5 shows a further embodiment of the present invention for dividing a coding unit.
6 illustrates a method of obtaining reference pixels for intra prediction.
7 illustrates an embodiment of prediction modes used for intra picture prediction.
8 is a diagram illustrating an example of a transform block having a size of 16 × 16 and a sub transform block of 4 × 4.
9 is a diagram illustrating an embodiment of encoding Transform sub-block coefficients.
10 is a diagram illustrating an example of code hiding of one transform coefficient in a transform coefficient group.
11 is a diagram illustrating an example of code hiding for two transform coefficients in a transform coefficient group.
12 is a grouping of prediction modes used for intra prediction.
FIG. 13 is a diagram illustrating a method of measuring a discontinuity of some upper and left samples of a neighboring reconstructed block and upper and left sample values of a current coding block.
14 is a diagram illustrating a method of measuring a discontinuity of some upper and left samples of a neighboring reconstructed block and upper and left sample values of a current coding block.
FIG. 15 is a diagram illustrating a sample configuration used when an intra prediction mode is included in group M1 of FIG. 12 when calculating a cost.
FIG. 16 is a diagram illustrating a sample configuration used when an intra prediction mode is included in group M3 of FIG. 12 when a cost is calculated.
FIG. 17 is a diagram illustrating a sample configuration used when an intra prediction mode is included in the group MO / M4 of FIG.
FIG. 18 is a diagram illustrating another example of a sample configuration used when an intra prediction mode is included in the group MO / M4 of FIG.
19 is a diagram illustrating an example of a sample configuration used when an intra prediction mode is included in a group M2 of FIG. 12 when a cost is calculated.
20 is a diagram illustrating another example of a sample configuration used when an intra prediction mode is included in group M2 of FIG.
21 is a diagram illustrating a converter equation used for transforming / inverse transforming a residual signal.
22 is a diagram showing an example of a cost configuration sample for a method of converting and ordering a transducer type according to a specified algorithm.

The terminology used herein is a general term that has been widely used as far as possible in consideration of functions in the present invention, but may vary according to the intention of a person skilled in the art, custom or the emergence of new technology. In addition, in certain cases, there is a term arbitrarily selected by the applicant, and in this case, the meaning will be described in the corresponding description of the invention. Therefore, it is to be understood that the terminology used herein is to be interpreted based on the actual meaning of the term and the contents throughout the specification, rather than simply on the name of the term.

In the present invention, the following terms may be interpreted based on the following criteria, and terms not described may be interpreted according to the following meanings. Coding can be interpreted as encoding or decoding in some cases, and information is a term that includes values, parameters, coefficients, elements, and the like. May be interpreted otherwise, the present invention is not limited thereto. 'Unit' is used to refer to a basic unit of image (picture) processing or a specific position of a picture, and in some cases, may be used interchangeably with terms such as 'block', 'partition' or 'region'. . Also, in the present specification, a unit may be used as a concept including a coding unit, a prediction unit, and a transform unit.

1 is a schematic block diagram of a video signal encoding apparatus according to an embodiment of the present invention. Referring to FIG. 1, the encoding apparatus 100 of the present invention is largely composed of a transformer 110, a quantizer 115, an inverse quantizer 120, an inverse transformer 125, a filter 130, and a predictor ( 150 and the entropy coding unit 160.

The transform unit 110 obtains a transform coefficient value by converting the pixel value of the received video signal. For example, a discrete cosine transform (DCT) or a wavelet transform may be used. In particular, the discrete cosine transform divides the input picture signal into blocks having a predetermined size to perform the transform. In the transform, the coding efficiency may vary depending on the distribution and the characteristics of the values in the transform domain.

The quantization unit 115 quantizes the transform coefficient value output from the transform unit 110. The inverse quantization unit 120 inverse quantizes the transform coefficient value, and the inverse transform unit 125 restores the original pixel value by using the inverse quantized transform coefficient value.

The filtering unit 130 performs a filtering operation for improving the quality of the reconstructed picture. For example, a deblocking filter and an adaptive loop filter may be included. The filtered picture is output or stored in a decoded picture buffer 156 for use as a reference picture.

Rather than coding the picture signal as it is, the prediction unit 150 predicts the picture using a region already coded, and adds a residual value between the original picture and the predicted picture to the predicted picture to improve coding efficiency. The method of obtaining is used. The intra predictor 152 performs intra prediction within the current picture, and the inter predictor 154 predicts the current picture using a reference picture stored in the decoded picture buffer 156. The intra prediction unit 152 performs intra prediction from the reconstructed regions in the current picture, and transmits intra coding information to the entropy coding unit 160. The inter predictor 154 may further include a motion estimator 154a and a motion compensator 154b. The motion estimation unit 154a obtains a motion vector value of the current region by referring to the restored specific region. The motion estimator 154a transmits the position information (reference frame, motion vector, etc.) of the reference region to the entropy coding unit 160 to be included in the bitstream. The motion compensation unit 154b performs inter-screen motion compensation by using the motion vector value transmitted from the motion estimation unit 154a.

The entropy coding unit 160 entropy codes the quantized transform coefficients, inter picture encoding information, intra picture encoding information, and reference region information input from the inter prediction unit 154 to generate a video signal bitstream. In the entropy coding unit 160, a variable length coding (VLC) scheme, arithmetic coding, or the like may be used. The variable length coding (VLC) scheme converts input symbols into consecutive codewords, which may have a variable length. For example, frequently occurring symbols are represented by short codewords and infrequently occurring symbols by long codewords. As a variable length coding method, a context-based adaptive variable length coding (CAVLC) method may be used. Arithmetic coding converts consecutive data symbols into a single prime number, which can obtain the optimal fractional bits needed to represent each symbol. Context-based Adaptive Binary Arithmetic Code (CABAC) may be used as the arithmetic coding.

The generated bitstream is encapsulated in a NAL unit. The NAL unit includes a coded slice segment, which consists of an integer number of coding tree units. In order to decode the bitstream in the video decoder, the bitstream must first be divided into NAL unit units, and then each separated NAL unit must be decoded.

2 is a schematic block diagram of a video signal decoding apparatus 200 according to an embodiment of the present invention. Referring to FIG. 2, the decoding apparatus 200 of the present invention largely includes an entropy decoding unit 210, an inverse quantization unit 220, an inverse transform unit 225, a filtering unit 230, and a prediction unit 250.

The entropy decoding unit 210 entropy decodes the video signal bitstream and extracts transform coefficients and motion information for each region. The inverse quantization unit 220 inverse quantizes the entropy decoded transform coefficient, and the inverse transform unit 225 restores the original pixel value by using the inverse quantized transform coefficient.

Meanwhile, the filtering unit 230 performs filtering on the picture to improve the picture quality. This may include a deblocking filter to reduce block distortion and / or an adaptive loop filter to remove distortion of the entire picture. The filtered picture is output or stored in a decoded picture buffer (256) for use as a reference picture for the next frame.

In addition, the predictor 250 of the present invention includes an intra predictor 252 and an inter predictor 254, and includes a coding type decoded by the entropy decoder 210 described above, a transform coefficient for each region, The predictive picture is reconstructed by using motion information.

In this regard, the intra prediction unit 252 performs the intra prediction from the decoded samples in the current picture. The inter prediction unit 254 generates the predictive picture using the reference picture and the motion information stored in the decoded picture buffer 256. The inter predictor 254 may again include a motion estimator 254a and a motion compensator 254b. The motion estimator 254a obtains a motion vector indicating the positional relationship between the current block and the reference block of the reference picture used for coding and transfers the motion vector to the motion compensator 254b.

The predicted value output from the intra predictor 252 or the inter predictor 254 and the pixel value output from the inverse transform unit 225 are added to generate a reconstructed video frame.

Hereinafter, a method of dividing a coding unit, a prediction unit, etc. with reference to FIGS. 3 to 5 in the operations of the encoding apparatus 100 and the decoding apparatus 200 will be described.

A coding unit is a process such as intra / inter prediction, transform, quantization and / or entropy coding in the processing of the video signal described above. Means a basic unit for processing a picture. The size of the coding unit used in coding one picture may not be constant. The coding unit may have a rectangular shape, and one coding unit may be further divided into several coding units.

3 shows an embodiment of the present invention for dividing a coding unit. For example, one coding unit having a size of 2N × 2N may be divided into four coding units having a size of N × N. The splitting of such coding units can be done recursively, and not all coding units need to be split in the same form. However, there may be a limitation on the size of the maximum coding unit and / or the size of the minimum coding unit for convenience in coding and processing.

For one coding unit, information indicating whether the corresponding coding unit is split may be stored. FIG. 4 illustrates an embodiment of a method for hierarchically representing a division structure of a coding unit illustrated in FIG. 3 using a flag value. Information indicating whether a coding unit is divided may be allocated to a value of '1' when the corresponding unit is divided and '0' when it is not divided. As shown in FIG. 4, when a flag value indicating whether to split is 1, a coding unit corresponding to a corresponding node is divided into 4 coding units, and when 0, a processing process for the coding unit is performed without being divided further. Can be.

The structure of the coding unit described above may be represented using a recursive tree structure. That is, a coding unit split into another coding unit with one picture or maximum size coding unit as a root has as many child nodes as the number of split coding units. Thus, coding units that are no longer split become leaf nodes. Assuming that only square division is possible for one coding unit, one coding unit may be divided into up to four other coding units, so a tree representing the coding unit may be in the form of a quad tree.

In the encoder, an optimal coding unit size is selected according to characteristics (eg, resolution) of a video picture or in consideration of coding efficiency, and information about the same or information capable of deriving the coding unit may be included in the bitstream. For example, the size of the largest coding unit and the maximum depth of the tree can be defined. In the case of square division, since the height and width of the coding unit are half the height and width of the coding unit of the parent node, the minimum coding unit size can be obtained using the above information. Alternatively, the minimum coding unit size and the maximum depth of the tree may be defined in advance, and the maximum coding unit size may be derived and used. Since the size of the unit changes in a multiple of 2 in square division, the size of the actual coding unit is represented by a logarithm of the base of 2, thereby improving transmission efficiency.

The decoder may obtain information indicating whether the current coding unit is split. This information can be obtained only if the information is obtained (transmitted) under certain conditions, thereby increasing efficiency. For example, the condition that the current coding unit can be divided is that the current coding unit is divided by the current coding unit size at the current position is smaller than the picture size and the current unit size is larger than the preset minimum coding unit size. Information indicating whether or not it can be obtained.

If the information indicates that the coding unit is split, the size of the coding unit to be split is half of the current coding unit, and is split into four square coding units based on the current processing position. The above process can be repeated for each divided coding units.

5 shows a further embodiment of the present invention for dividing a coding unit. According to a further embodiment of the present invention, the aforementioned quad tree type coding unit may be further divided into a binary tree structure of horizontal division or vertical division. That is, square quad tree splitting is first applied to the root coding unit, and rectangular binary tree splitting can be additionally applied at leaf nodes of the quad tree. According to an embodiment, the binary tree split may be symmetric horizontal split or symmetric vertical split, but the present invention is not limited thereto.

At each split node of the binary tree, a flag indicating the split type (ie, horizontal split or vertical split) may be additionally signaled. According to an embodiment, when the value of the flag is '0', horizontal division may be indicated, and when the value of the flag is '1', vertical division may be indicated.

However, in the embodiment of the present invention, the splitting method of the coding unit is not limited to the above-described methods, and asymmetric horizontal / vertical splitting, a triple tree divided into three rectangular coding units, and the like may be applied.

Picture prediction (motion compensation) for coding is directed to coding units (i.e. leaf nodes of the coding unit tree) that are no longer divided. The basic unit for performing such prediction is hereinafter referred to as a prediction unit or a prediction block.

Hereinafter, the term unit used in the present specification may be used as a term to replace the prediction unit, which is a basic unit for performing prediction. However, the present invention is not limited thereto and may be broadly understood as a concept including the coding unit.

The decoded portion of the current picture or other pictures in which the current unit is included may be used to reconstruct the current unit in which decoding is performed. An intra picture or I picture (slice) that uses only the current picture for reconstruction, that is, performs only intra picture prediction, and an inter picture (slice) that can perform both intra picture and inter picture prediction. ). A picture (slice) that uses up to one motion vector and reference index to predict each unit of an inter picture (slice) is called a predictive picture or P picture (slice), and up to two motion vectors and a reference index A picture using a slice is called a bi-predictive picture or a B picture.

The intra prediction unit performs intra prediction to predict the pixel value of the target unit from the reconstructed regions in the current picture. For example, the pixel value of the current unit can be predicted from the reconstructed pixels of units located on the left and / or top, centering on the current unit. In this case, the units located on the left side of the current unit may include a left unit, an upper left unit, and a lower left unit adjacent to the current unit. In addition, units located at the top of the current unit may include a top unit, a left top unit, and a top right unit adjacent to the current unit.

Meanwhile, the inter prediction unit performs inter prediction for predicting a pixel value of a target unit by using information of other reconstructed pictures other than the current picture. In this case, a picture used for prediction is referred to as a reference picture. Which reference region is used to predict the current unit in the inter prediction process may be indicated by using an index indicating a reference picture including the reference region, motion vector information, and the like.

The inter prediction may include L0 prediction, L1 prediction, and bi-prediction. L0 prediction means prediction using one reference picture included in the L0 picture list, and L1 prediction means prediction using one reference picture included in the L1 picture list. For this purpose, one set of motion information (eg, a motion vector and a reference picture index) may be required. In the bi-prediction method, up to two reference regions may be used, and these two reference regions may exist in the same reference picture or may exist in different pictures, respectively. That is, in the pair prediction method, up to two sets of motion information (eg, a motion vector and a reference picture index) may be used, and two motion vectors may correspond to the same reference picture index or may be different from each other. It may also correspond. In this case, the reference pictures may be displayed (or output) before or after the current picture in time.

The reference unit of the current unit may be obtained using the motion vector and the reference picture index. The reference unit exists in a reference picture having the reference picture index. In addition, a pixel value or an interpolated value of a unit specified by the motion vector may be used as a predictor of the current unit. For motion prediction with pixel accuracy on a sub-pel basis, for example, an 8-tap interpolation filter may be used for the luminance signal and a 4-tap interpolation filter may be used for the chrominance signal. However, the interpolation filter for motion prediction in the subpel unit is not limited thereto. As such, using motion information, motion compensation is performed to predict the texture of the current unit from a previously decoded picture.

Hereinafter, the intra prediction method according to an embodiment of the present invention will be described in more detail with reference to FIGS. 6 and 7. As described above, the intra prediction unit predicts pixel values of the current unit by using adjacent pixels located at the left and / or the top of the current unit as reference pixels.

As shown in FIG. 6, when the size of the current unit is NXN, reference pixels may be set using up to 4N + 1 adjacent pixels located on the left and / or top of the current unit. If at least some of the adjacent pixels to be used as the reference pixels have not been reconstructed yet, the intra predictor may obtain the reference pixels by performing a reference sample padding process according to a preset rule. In addition, the intra predictor may perform a reference sample filtering process to reduce an error of intra prediction. That is, the reference pixels may be obtained by filtering the pixels acquired by the adjacent pixels and / or the reference sample padding process. The intra predictor predicts the pixels of the current unit by using the reference pixels thus obtained.

7 illustrates one embodiment of prediction modes used for intra picture prediction. For intra prediction, intra prediction mode information indicating an intra prediction direction may be signaled. When the current unit is an intra picture prediction unit, the video signal decoding apparatus extracts intra picture prediction mode information of the current unit from the bitstream. The intra prediction unit of the video signal decoding apparatus performs the intra prediction on the current unit based on the extracted intra prediction mode information.

According to an embodiment of the present invention, the intra prediction mode may include a total of 67 modes. Each intra prediction mode may be indicated through a preset index (ie, an intra mode index). For example, as shown in FIG. 7, intra mode index 0 indicates a planar mode, intra mode index 1 indicates a DC mode, and intra mode indexes 2 to 66 indicate different directional modes (ie, , Angle modes), respectively. The intra prediction unit determines reference pixels and / or interpolated reference pixels to be used for intra prediction of the current unit based on the intra prediction mode information of the current unit. When the intra mode index indicates a specific direction mode, a reference pixel or interpolated reference pixel corresponding to the specific direction from the current pixel of the current unit is used for prediction of the current pixel. Thus, different sets of reference pixels and / or interpolated reference pixels may be used for intra prediction according to the intra prediction mode.

After the intra prediction of the current unit is performed by using the reference pixels and the intra prediction mode information, the video signal decoding apparatus adds the residual signal of the current unit obtained from the inverse transform unit with the intra prediction of the current unit to determine the current unit. Restore pixel values.

8 illustrates an example of a transform block having a size of 16 × 16 and a sub transform block of 4 × 4. After transforming by sub-conversion block unit, the coefficients (hereinafter, referred to as transform coefficients) are scanned in various ways and represented as various types of syntax elements, and then input into CABAC (Context-Based Adaptive Binary Arithmetic Coding) as a probability model or bypass. The sub transform block can be composed of various sizes, such as square or rectangular.

9 is a diagram illustrating an example of encoding Transform sub-block coefficients.

9-1 illustrates an embodiment of transform coefficients of a coefficient group (CG) configured of 4x4 units in a transform block. 9-2 uses Significance flag, coefficient level greater than 1, coefficient level greater than 2, Sign flag, and remaining level (remaining absolute level) flags to encode FIG. 9-1. The significance flag is an indicator of the location of the conversion factor. coefficient level greater than 1 is an indicator of whether the absolute value is greater than or less than 1 of the conversion coefficients greater than 0. It is only displayed for the first to eighth coefficients in the scanning order. coefficient level greater than2 is used as an indicator only for the first change coefficient indicated by coefficient level greater than1, whose absolute value is greater than 2, depending on the scanning order. The sign flag is an indicator that indicates the sign information of the conversion coefficient. The remaining level (remaining absolute level) indicates the magnitude of the remaining absolute value without the above indicators as an integer.

10 shows an example of code hiding for one transform coefficient in a transform coefficient group.

One embodiment relates to code hiding for one transform coefficient -3. Fig. 10-1 can be considered separately as in Fig. 10-2, and for the actual sign (-), the encoder transforms the sign of the transform coefficient to be hidden by transform / quantization / dequantization / inverse transform for each of the two code combinations. For all or part of the group (all or part of the group can be limited to inverse transformation only), the cost value for each code combination is calculated by reconstructing the sample value (residual) to determine the discontinuity described in FIG. . Consideration can be given to minimizing the number of inverse transforms. Only one non-zero coefficient with an absolute value of 1 can be inversely transformed and precomputed and stored in a lookup table in the form of a reconstructed elemental residual or template. Sort by the minimum cost value and use 1 bit for the smallest of them. If the code combination of cost matches the actual sign of the original conversion coefficient, it is 1, and if it is not, 0 is determined. do. The 1-bit can be used to create a context model whether the code combination having the minimum cost is correct or not.

11 is a diagram showing an example of code hiding for two transform coefficients in a transform coefficient group.

By hiding two code bits, 2 ^ 2 code combinations are possible. For example, the code combination 1: (++), code combination 2: (+-), code combination 3: (-+), code combination 4: (-). The encoder reconstructs the transform coefficient group by transform / quantization / inverse quantization / inverse transformation for each of the four code combinations for the code hiding to encode the codes. Calculate the cost value for. If the code having the minimum cost is a Hakhwan value intended by the encoder, the decoder may calculate the cost and apply the code having the minimum cost to restore the current block. However, the accuracy may vary depending on the magnitude of the absolute value of the residual signal. If the value is large, the cost is increased if the sign is not correct because the value difference of the transformed / inversely transformed residual signal is large. However, when the value is small, the accuracy of cost value calculation may be reduced because the magnitude difference of the restored residual signal is small.

12 is a grouping of prediction modes used for intra prediction.

Among the intra prediction modes, one non-directional prediction mode group such as DC and Planar and an angular mode indicating directionality are illustrated in five groups. Depending on the intra prediction mode, the method of selecting a reference sample in the cost calculation method may be different. If the intra prediction mode is included in the predetermined group, the cost calculation method used in the group is used. Alternatively, the sample value may be determined by interpolating based on the angle of the prediction mode. Two intersample linear interpolation methods / weighted interpolation methods can be used. The interpolation method between two samples may use the prediction mode based sample value acquisition method used in HEVC / H.256.

FIG. 13 is a diagram illustrating a method of measuring a discontinuity of some upper and left samples of a neighboring reconstructed block and upper and left sample values of a current coding block. It can be defined as Equation 1 below to calculate the cost value. The method of calculating the cost can be defined and used in more various ways, and Equation 1 is only one embodiment thereof. The sample configuration required for the calculation can be configured in various forms. In the present invention, the left and right samples and the neighboring samples will be described in the form of using all three or four sides can be extended.

where R is reconstructed neighbors, P is prediction of the current block, and r is the residual hypothesis. The term (-R _-1 + 2R ₀ -P ₁ ) can be calculated only once per block and only residual hypothesis is subtracted.

FIG. 14 is a diagram illustrating a method of measuring a discontinuity of some upper and left samples of a neighboring reconstructed block and upper and left sample values of a current coding block. FIG. 14 differs from FIG. 13 in that the sample configuration method is at the top left. Alternatively, in the configuration of FIG. 14, the sample at the upper left corner may be configured to be calculated on both the right side and the left side. 13 and 14 may be applied to the non-directional prediction mode among the intra prediction modes.

FIG. 15 is a diagram illustrating a sample configuration used when an intra prediction mode is included in group M1 of FIG. When the intra prediction mode is the horizontal mode, the prediction is performed by using the left reference sample value of the current block. The difference between the reference sample and the original sample may be smallest. Therefore, if the sign of the residual signal is changed, the difference is large when calculating the cost. It is possible to increase the probability that the code combination having the minimum cost is the correct answer.

FIG. 16 is a diagram illustrating a sample configuration used when an intra prediction mode is included in group M3 of FIG. 12 when a cost is calculated. When the intra prediction mode is the vertical mode, the prediction is performed using the right reference sample value of the current block. The difference between the reference sample and the original sample may be the smallest. Therefore, if the sign of the residual signal is changed, the difference is large when calculating the cost. It is possible to increase the probability that the code combination having the minimum cost is the correct answer.

FIG. 17 is a diagram illustrating a sample configuration used when an intra prediction mode is included in the group MO / M4 of FIG. If the intra prediction mode is in the horizontal diagonal (M0) / vertical diagonal (M4) direction mode, the difference between the reference sample and the original sample may be the smallest when the prediction is made using the reference sample value in the horizontal / stock diagonal direction of the current block. have. Therefore, if the sign of the residual signal is changed, the difference is large when calculating the cost. It is possible to increase the probability that the code combination having the minimum cost is the correct answer.

FIG. 18 is a diagram illustrating another example of a sample configuration used when an intra prediction mode is included in the group MO / M4 of FIG. Unlike in FIG. 17, a sample configuration of a neighboring block exceeds the height / width of the current block in such a manner that both left and right samples of the current block are used for cost calculation.

19 is a diagram illustrating an example of a sample configuration used when an intra prediction mode is included in group M2 of FIG. 12 when a cost is calculated. When the intra prediction mode is the diagonal (M2) direction mode, the prediction is performed using the reference sample value in the diagonal direction of the current block, and the difference between the reference sample and the original sample may be smallest. Therefore, if the sign of the residual signal is changed, the difference is large when calculating the cost. It is possible to increase the probability that the code combination having the minimum cost is the correct answer.

20 is a diagram illustrating another example of a sample configuration used when an intra prediction mode is included in group M2 of FIG. Unlike in FIG. 19, an example in which all samples of the prediction block are used is added with neighboring samples in the upper left corner. Although there is a burden of configuring additional neighboring samples, the accuracy can be increased by calculating the cost using the left and right sample modes in the prediction mode.

21 is a diagram illustrating a converter equation used for transforming / inverse transforming a residual signal. The video signal generates a prediction block using intra / inter prediction methods. The encoder finds the difference between the original block and the prediction block and calls it a residual signal. The residual signal is quantized, transformed, and coded. The decoder performs decoding, inverse quantization, and inverse transformation to restore the residual signal, and generate a reconstructed block in addition to the block obtained by prediction. The encoder / decoder can use one of several types of converters used for conversion in quantization and dequantization. In addition, additional transform may be performed after the transform / inverse transform once on the prediction transform block. This can be done for some areas of the once converted area. The area can be set and used in various forms.

22 is a diagram showing an example of a cost configuration sample for a method of converting and ordering a transducer type according to a specified algorithm. There can be many different types of converters used for further conversion, so that the encoder can inform the decoder of additional indicators. For example, if there are four types of additional converters, using fixed bits will always use two bits of information. To reduce this information, we can use a binarization method called Truncated unary. For example, it is binarized in the form of 0, 10, 110, and 111, and a minimum of 1 bit and a maximum of 3 bits are required. There is a need for an algorithm in which the decoder can configure the information of the indicator to be informed by the encoder for each information unit, that is, a coding unit / conversion unit / prediction unit. For example, the cost calculation is performed using the method of FIG. In this case, the first indicator using the least bit that the lowest cost is calculated by calculating the cost in the form of FIG. 22 by quantizing / dequantizing the residual signal and then transforming / inverting the residual signal and generating a reconstruction block for the prediction block, respectively. And use the binarization bit 0. The converter type with the highest cost is the fourth indicator and uses the binarization bit 111. This allows the encoder and the decoder to infer the type of converter corresponding to the indicator to the algorithm in the same manner. In FIG. 22, a corresponding cost may be calculated using a plurality of neighboring samples of the left column and the right row of the prediction block. If there is a reconstructed block on the right side of the current prediction block, the same cost calculation method can be applied to three sides in the same way. If there is a recovery block for the downward direction, it can be extended. In addition, the present invention may be adaptively applied to the planes with the reconstruction block among the four planes.

In the above described the present invention through specific embodiments, those skilled in the art can make modifications, changes without departing from the spirit and scope of the present invention. Therefore, what can be easily inferred by the person of the technical field to which this invention belongs from the detailed description and the Example of this invention is interpreted as belonging to the scope of the present invention.

100: encoding device 200: decoding device

Claims (1)

Video signal processing apparatus and method.

Images