KR102726470B1 - A method of decoding a video signal and an apparatus having the same - Google Patents

Abstract

The present invention relates to a method for decoding a video signal and a device thereof. A method for decoding a video signal and a device thereof according to one embodiment of the present invention comprises the steps of: obtaining transform region information indicating at least one transform region included in the transform block, based on the transform region information; scanning a plurality of transform coefficient groups included in a first transform region; and scanning a plurality of transform coefficient groups included in a second transform region within the transform block.

Description

{A METHOD OF DECODING A VIDEO SIGNAL AND AN APPARATUS HAVING THE SAME}

The present invention relates to a method for decoding a video signal and a device thereof, and more particularly, to a method for decoding a video signal and a device thereof for scanning a group of transform coefficients for each of a plurality of transform areas.

Recently, the demand for high-resolution, high-quality images such as HD (High Definition) images and UHD (Ultra High Definition) images is increasing in various application fields. As the image data becomes higher in resolution and quality, the amount of data increases relatively compared to existing image data. Therefore, when transmitting the image data using media such as existing wired and wireless broadband lines or storing it using existing storage media, the transmission cost and storage cost increase. In order to solve these problems that occur as the image data becomes higher in resolution and quality, high-efficiency image compression technologies can be utilized.

In video compression technologies, various effective methods are adopted to improve the compression ratio by more than two times compared to conventional compression technologies. As inter-screen prediction technologies, methods using motion vector predictors, merge mode, and skip mode are used. These are all technologies for efficient inter-screen prediction.

In addition, existing video codecs divided a picture into macro blocks, which are 16x16 sized blocks, and divided them, but recently, HEVC uses a coding unit (CU) as the basic encoding unit. The coding unit can be divided up to the maximum and minimum sizes specified by the parameter values stored in the sequence parameter set. The basic unit for predictive encoding is defined as a prediction unit (PU), and one coding unit is divided into a plurality of prediction units and predicted. In addition, the encoding and decoding order of each coding unit uses the raster scan method.

In this way, HEVC can effectively consider the spatial resolution and block characteristics of an image for encoding by using coding units of various sizes. In general, when the resolution of an image is small or pixel values change locally greatly, it can be efficient to perform intra-screen and inter-screen prediction using coding units of small sizes. In this way, when coding units of small sizes are used, the amount of header bits required for encoding increases, but there is an advantage in that the prediction is relatively precise, so that the quantization error and the amount of bits required for encoding transform coefficients are reduced.

On the other hand, in areas where the spatial resolution of the image is large or where the changes in pixel values are small, using a large coding unit can increase the encoding efficiency. In this case, even if a large coding unit is used, the prediction error tends not to increase significantly compared to when predicting using a small coding unit, so when encoding these blocks, it can be efficient to save the transmission bit amount by using a large coding unit. However, even if various conventional coding units are used, there is a disadvantage in that it is difficult to efficiently code various images with high resolution.

The problem to be solved by the present invention is to provide a method for decoding a video signal and a device therefor that improves the coding efficiency of intra-screen prediction by using transform blocks of various shapes.

In addition, another problem to be solved by the present invention is to provide a method for decoding a video signal and a device therefor, which can increase coding efficiency by coding a group of transform coefficients in a low-frequency region before a high-frequency region.

According to one embodiment of the present invention for solving the above problem, a method for decoding a video signal comprises: a method for scanning a transform block including a plurality of transform coefficient groups, the step of obtaining transform region information indicating at least one transform region included in the transform block; a step of scanning a plurality of transform coefficient groups included in a first transform region based on the transform region information; and a step of scanning a plurality of transform coefficient groups included in a second transform region within the transform block.

The above multiple transform coefficient groups can be scanned such that the transform coefficient group of the low frequency region precedes the transform coefficient group of the high frequency region.

In one embodiment, the transform domain information may be received from an encoder or obtained from at least one of a sequence parameter set (SPS) and a slice header. Additionally, the transform domain information may be obtained from a decoder in a predetermined manner.

Before the step of obtaining the above transformation area information, a step of determining whether the transformation block is a non-square block may be further included. The determining step may be performed based on the horizontal length and the vertical length of the transformation block.

According to one embodiment of the present invention for solving the above-described other problem, a video signal decoding device may include a transform region information obtaining unit that obtains transform region information indicating at least one transform region included in a transform block; and a transform coefficient group scanning unit that sequentially scans a plurality of transform coefficient groups included in each of the at least one transform region based on the transform region information.

According to an embodiment of the present invention, a method for decoding a video signal and a device therefor are provided, which improve the coding efficiency of intra-screen prediction by dividing the transform block into at least one transform area including some of a plurality of transform coefficient groups when the transform block is a non-square block and sequentially scanning the transform coefficient groups included in the transform area.

In addition, according to another embodiment of the present invention, a method for decoding a video signal and a device thereof are provided, which can increase coding efficiency by dividing a transform block into at least one transform area and sequentially scanning transform coefficient groups included in the divided transform areas, thereby coding transform coefficient groups in a low-frequency area before those in a high-frequency area.

FIG. 1 is a block diagram schematically illustrating a video encoding device according to one embodiment of the present invention.
FIG. 2 is a block diagram schematically illustrating a video decoding device according to one embodiment of the present invention.
Figure 3 is intended to explain the structure of a conventional conversion block.
Figure 4 is for explaining a group of transform coefficients that constitute a conventional 16x16 transform block.
Figure 5 is for explaining a group of conversion coefficients according to a general method and a conversion scan method of the group of conversion coefficients.
FIGS. 6A to 6D are for explaining types of transformation coefficient groups and scanning methods of the transformation coefficient groups according to a general method.
FIGS. 7A and 7B illustrate examples of applying a general scan method to a conversion block according to one embodiment of the present invention.
Figure 8 is an example of applying a general scan method to the transform coefficients of a 16x8 transform block.
FIG. 9 is a flowchart illustrating a method for scanning a group of conversion coefficients according to one embodiment of the present invention.
FIG. 10 illustrates a device for scanning a group of conversion coefficients according to one embodiment of the present invention.
FIGS. 11A and 11B illustrate a method of scanning a transform coefficient group for a non-square transform block according to one embodiment of the present invention.
FIGS. 12A to 13D are examples for explaining various methods of scanning a transform coefficient group for a non-square transform block according to one embodiment of the present invention.

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

The embodiments of the present invention are provided so that those skilled in the art will more fully understand the present invention, and the following embodiments may be modified in various other forms, and the scope of the present invention is not limited to the following embodiments. Rather, these embodiments are provided so that the present disclosure will be more faithful and complete, and so that those skilled in the art will fully convey the spirit of the present invention.

Additionally, the thickness and size of each unit in the drawings are exaggerated for convenience and clarity of explanation, and like symbols in the drawings represent like elements. As used herein, the term "and/or" includes any one and any combination of one or more of the listed items.

The terminology used herein is used to describe particular embodiments and is not intended to be limiting of the invention. As used herein, the singular forms "a", "an" and "the" include plural forms unless the context clearly dictates otherwise. Also, when used herein, the words "comprise" and/or "comprising" specify the presence of stated features, numbers, steps, operations, elements, elements and/or groups thereof, but do not preclude the presence or addition of one or more other features, numbers, operations, elements, elements and/or groups thereof.

Although the terms first, second, etc. are used herein to describe various components, elements, parts, regions, and/or portions, it is to be understood that these components, elements, parts, regions, and/or portions are not limited by these terms. These terms are only used to distinguish one component, element, part, region, or portion from another. Thus, a first component, element, part, region, or portion described below may refer to a second component, element, part, region, or portion without departing from the teachings of the present invention. In addition, the terms and/or include a combination of a plurality of relatedly described items or any one of a plurality of relatedly described items.

When a component is referred to as being "connected" or "connected" to another component, it should be understood that it is directly connected or connected to said other component, as well as when there is another component between said component and said other component. However, when a component is referred to as being "directly connected" or "directly connected" to another component, it should be understood that said component and said other component are directly connected or connected without any other component in between.

Hereinafter, embodiments of the present invention will be described with reference to drawings that schematically illustrate ideal embodiments of the present invention. In the drawings, for example, the size and shape of members may be exaggerated for convenience and clarity of explanation, and variations in the illustrated shapes may be expected during actual implementation. Accordingly, embodiments of the present invention should not be construed as being limited to specific shapes of regions illustrated in this specification.

FIG. 1 is a block diagram schematically illustrating an image encoding device according to one embodiment of the present invention.

Referring to FIG. 1, an image encoding device (100) includes an image segmentation unit (105), an inter-screen prediction unit (110), an intra-screen prediction unit (115), a transformation unit (120), a quantization unit (125), a reordering unit (130), an entropy encoding unit (135), an inverse quantization unit (140), an inverse transformation unit (145), a filter unit (150), and a memory (155).

Each component shown in Fig. 1 is independently depicted to indicate different characteristic functions in the video encoding device, and does not mean that each component is composed of separate hardware or a single software configuration unit. That is, each component is listed and included as a separate component for convenience of explanation, and at least two components among each component may be combined to form a single component, or a single component may be divided into multiple components to perform a function. Embodiments in which each of these components is integrated or separated may also be included in the scope of the present invention as long as they do not deviate from the essential aspects of the present invention.

The image segmentation unit (105) can segment the input image into at least one processing unit. The processing unit may be a prediction block (hereinafter referred to as “PU”), a transform block (hereinafter referred to as “TU”), or a coding block (hereinafter referred to as “CU”). However, in this specification, for convenience of explanation, a prediction block may be expressed as a prediction unit, a transform block may be expressed as a transform unit, and an encoding or decoding block may be expressed as an encoding unit or a decoding unit.

In one embodiment, the image segmentation unit (105) can segment an image into a plurality of combinations of encoding blocks, prediction blocks, and transform blocks, and encode the image by selecting a combination of the encoding blocks, prediction blocks, and transform blocks based on a predetermined criterion (e.g., a cost function).

For example, one image may be divided into multiple coding blocks. In one embodiment, one image may be divided into said coding blocks using a recursive tree structure such as a quad tree structure or a binary tree structure, and a coding block that is divided into other coding blocks with one image or the largest coding unit as the root may be divided with as many child nodes as the number of divided coding blocks. Through this process, a coding block that is no longer divided may become a leaf node. For example, if it is assumed that only a square partition is possible for one coding block, one coding block may be divided into, for example, four coding blocks. However, in the present invention, the coding block, the prediction block, and/or the transformation block are not limited to symmetric partitioning when divided, but asymmetric partitioning is also possible, and not only four partitions but also two partitions are possible. However, this number of partitions is exemplary and the present invention is not limited thereto.

A prediction block may also be divided into at least one square or non-square shape of the same size within one coding block, and may be divided such that one prediction block among the divided prediction blocks within one coding block has a different shape and size from another prediction block. In one embodiment, the coding block and the prediction block may be the same. That is, prediction may be performed based on the divided coding block without distinguishing between the coding block and the prediction block.

The prediction unit may include an inter-prediction unit (110) that performs inter-prediction and an intra-prediction unit (115) that performs intra-prediction. In order to increase coding efficiency, rather than encoding the image signal as it is, the image is predicted using a specific area within the image that has already been encoded and decoded, and the residual value between the original image and the predicted image is encoded. In addition, prediction mode information, motion vector information, etc. used for prediction may be encoded together with the residual value by the entropy encoding unit (135) and transmitted to the decoding unit. In the case of using a specific encoding mode, it is also possible to encode the original block as it is and transmit it to the decoding unit without generating a prediction block through the inter-prediction unit (110) and the intra-prediction unit (115).

In one embodiment, the inter-screen prediction unit (110) and the intra-screen prediction unit (115) can determine whether to perform inter-screen prediction or intra-screen prediction for a prediction block, and can determine specific information according to each of the above prediction methods, such as an inter-screen prediction mode, a motion vector, and a reference image. In this case, the processing unit where prediction is performed, the prediction method, and the detailed processing unit may be different. For example, even if the prediction mode and the prediction method are determined according to the prediction block, the prediction may be performed according to the transformation block.

The inter-screen prediction unit (110) and the intra-screen prediction unit (115) can perform prediction on the processing units of the images divided by the image segmentation unit (105) and generate prediction blocks composed of predicted samples. The image processing units in the inter-screen prediction unit (110) and the intra-screen prediction unit (115) can be coding block units, transformation block units, or prediction block units.

The inter-screen prediction unit (110) can predict a prediction block based on information of at least one image among the previous or subsequent images of the current image, and in some cases, can predict a prediction block based on information of a portion of the current image where coding has been completed. The inter-screen prediction unit (110) can include a reference image interpolation unit, a motion prediction unit, and a motion compensation unit.

In one embodiment, the information of one or more images used for prediction in the inter-screen prediction unit (110) may be information of images that have already been encoded and decoded, or information of images that have been transformed and stored in an arbitrary manner. For example, the image transformed and stored in an arbitrary manner may be an image that has been enlarged or reduced from an image that has been encoded and decoded, or may be an image that has transformed the brightness of all pixel values in the image, or a color format.

The reference image interpolation unit can receive reference image information from the memory (155) and generate pixel information below an integer pixel from the reference image. In the case of luminance pixels, pixel information below an integer can be generated in units of 1/4 pixels by using a DCT-based 8-tap interpolation filter (DCT-based Interpolation Filter) with different filter coefficients. In the case of a chrominance signal, pixel information below an integer can be generated in units of 1/8 pixels by using a DCT-based 4-tap interpolation filter (DCT-based Interpolation Filter) with different filter coefficients. However, the type of filter and the unit for generating pixel information below an integer are not limited thereto, and the unit for generating pixel information below an integer can be determined by using various interpolation filters.

The motion prediction unit can perform motion prediction based on the reference image interpolated by the reference image interpolation unit. Various methods can be used to derive the motion vector. The motion vector can have a motion vector value in integer pixel units or 1/2 or 1/4 pixel units based on the interpolated pixel. In one embodiment, the motion prediction unit can predict the prediction unit of the current block by using a different motion prediction method. Various methods can be used for the motion prediction method, including the Merge method, the Advanced Motion Vector Prediction (AMVP) method, and the Skip method. In this way, information including the index of the reference image selected by the inter-screen prediction unit (110), the predicted motion vector (MVP), and the residual signal can be entropy coded and transmitted to the decoder.

Unlike inter-screen prediction, the intra-screen prediction unit (115) can generate a prediction block based on reference pixel information surrounding the current block, which is pixel information within the current image. If the surrounding blocks of the prediction block are blocks that have performed inter-screen prediction, that is, if the reference pixel is a pixel that has performed inter-screen prediction, the reference pixel included in the block that has performed inter-screen prediction can be replaced with reference pixel information of a surrounding block that has performed intra-screen prediction.

In addition, the intra-screen prediction unit (115) can use the most probable intra-screen prediction mode (MPM: Most Probable mode) obtained from neighboring blocks to encode the intra-screen prediction mode. According to various embodiments of the present invention, the most probable intra-screen prediction mode list (MPM List) composed of the most probable intra-screen prediction modes can be composed in various ways.

Even when the on-screen prediction unit (115) performs on-screen prediction, the processing unit where the prediction is performed and the processing unit where the prediction method and specific content are determined may be different from each other. For example, the prediction mode may be determined as a prediction unit (PU), so that the prediction may be performed in the prediction unit, or the prediction mode may be determined as a prediction unit, but the prediction may be performed in a transformation unit (TU). In one embodiment, the prediction mode may be determined as a coding block (CU) unit, and the coding block unit and the prediction unit may be the same, so that the prediction may be performed in the coding block unit.

The prediction mode of the intra-screen prediction can include 65 directional prediction modes and at least two non-directional modes. The non-directional modes can include a DC prediction mode and a planar mode. The number of the 67 inter-screen prediction modes is only exemplary, and the present invention is not limited thereto, and intra-screen prediction can be performed in more directional or non-directional modes to predict in various ways.

In one embodiment, intra-screen prediction may generate a prediction block after applying a filter to a reference pixel. In this case, whether to apply a filter to the reference pixel may be determined based on the intra-screen prediction mode and/or size of the current block.

A prediction unit (PU) can be determined from a coding unit (CU) that is no longer divided into various sizes and shapes. For example, in the case of inter-picture prediction, the prediction unit can have a size such as 2N x 2N, 2N x N, N x 2N, or N x N. In the case of intra-picture prediction, the prediction unit can have a size such as 2N x 2N or N x N (N is an integer), but intra-picture prediction can be performed not only in the forward size but also in the non-forward size shape. In this case, the prediction unit with the size of N x N can be set to be applied only in a specific case. In addition to the prediction units with the sizes described above, intra-picture prediction units with sizes such as N x mN, mN x N, 2N x mN, or mN x 2N (m is a fraction or an integer) can be further defined and used.

The residual value (residual block or residual signal) between the prediction block generated in the screen prediction unit (115) and the original block can be input to the conversion unit (120). In addition, prediction mode information, interpolation filter information, etc. used for prediction can be encoded together with the residual value in the entropy encoding unit (135) and transmitted to the decoder.

The transformation unit (120) can transform a residual block including residual value information of an original block and a prediction unit generated through the prediction unit (110, 115) as a transformation unit by using a transformation method such as a DCT (Discrete Cosine Transform), a DST (Discrete Sine Transform), or a KLT (Karhunen Loeve Transform). Whether to apply a DCT, DST, or KLT to transform a residual block can be determined based on the prediction mode information within the screen of the prediction unit used to generate the residual block.

A transform block in a transform unit (120) may be a TU, and the transform block may include a square block and/or a non-square block, and the transform blocks may have a square quad tree structure, a non-square quad tree structure, or a binary tree structure. In one embodiment, the size of a transform unit may be determined within a range of predetermined maximum and minimum sizes. In addition, one transform block may be further divided into sub-transform blocks, and the sub-transform blocks may include a square block and/or a non-square block, and the sub-transform blocks may have a square quad tree structure, a non-square quad tree structure, or a binary tree structure. Transform blocks having various sizes, shapes, and structures as described above may be used to effectively consider local characteristics of a residual signal and encode it.

The quantization unit (125) can quantize the residual values converted by the transformation unit (120) to generate quantization coefficients. In one embodiment, the converted residual values may be values converted to a frequency domain. The quantization coefficients may be changed according to the transformation unit or the importance of the image, and the values produced by the quantization unit (125) may be provided to the dequantization unit (140) and the reordering unit (130).

The rearrangement unit (130) can rearrange the quantization coefficients provided from the quantization unit (125). The rearrangement unit (130) can improve the encoding efficiency in the entropy encoding unit (135) by rearranging the quantization coefficients. The rearrangement unit (130) can rearrange the quantization coefficients in a two-dimensional block shape into a one-dimensional vector shape through a coefficient scanning method. The coefficient scanning method can determine which scan method is used depending on the size of the transformation unit and the prediction mode within the screen. The coefficient scanning method can include a zig-zag scan, a vertical scan that scans the coefficients in a two-dimensional block shape in the column direction, and a horizontal scan that scans the coefficients in a two-dimensional block shape in the row direction. In one embodiment, the rearrangement unit (130) can also improve the entropy encoding efficiency in the entropy encoding unit (135) by changing the order of coefficient scanning based on probabilistic statistics of the coefficients transmitted from the quantization unit.

The entropy encoding unit (135) can perform entropy encoding on the quantized coefficients rearranged by the rearrangement unit (130). The entropy encoding can utilize various encoding methods, such as, for example, Exponential Golomb, CAVLC (Context-Adaptive Variable Length Coding), and CABAC (Content-Adaptive Binary Arithmetic Coding).

The entropy encoding unit (135) can encode various information such as quantization coefficient information of the coding unit received from the rearrangement unit (130) and the prediction unit (110, 115), block type information, prediction mode information, division unit information, prediction unit information, transmission unit information, motion vector information, reference image information, block interpolation information, and filtering information. In addition, in one embodiment, the entropy encoding unit (135) can also make certain changes to the parameter set or syntax to be transmitted, if necessary.

The inverse quantization unit (140) inversely quantizes the values quantized in the quantization unit (125), and the inverse transformation unit (145) inversely transforms the values inversely quantized in the inverse quantization unit (140). The residual values generated in the inverse quantization unit (140) and the inverse transformation unit (145) can be combined with the predicted blocks predicted in the prediction units (110, 115) to generate a reconstructed block. The image composed of the generated reconstructed blocks can be a motion compensated image or an MC image (Motion Compensated Picture).

The above motion compensation image can be input to a filter unit (150). The filter unit (150) can include a deblocking filter unit, an offset correction unit (Sample Adaptive Offset, SAO), and an adaptive loop filter unit (Adaptive Loop Filter, ALF). In summary, the motion compensation image can be input to an offset correction unit to correct an offset after a deblocking filter is applied to the motion compensation image in the deblocking filter unit to reduce or remove blocking artifacts. The image output from the offset correction unit is input to the adaptive loop filter unit to pass through an ALF (Adaptive Loop Filter) filter, and the image passing through the filter can be transmitted to a memory (155).

Specifically describing the filter unit (150), the deblocking filter unit can remove distortion within a block generated at the boundary between blocks in a restored image. In order to determine whether to perform deblocking, it is possible to determine whether to apply a deblocking filter to the current block based on pixels included in several columns or rows included in the block. When applying a deblocking filter to a block, a strong filter or a weak filter can be applied depending on the required deblocking filtering strength. In addition, when applying the deblocking filter, when performing vertical filtering and horizontal filtering, horizontal filtering and vertical filtering can be processed in parallel.

The offset correction unit can correct the offset from the original image on a pixel basis for the residual block to which the deblocking filter is applied. In order to correct the offset for a specific image, the pixels included in the image are divided into a certain number of regions, and then the regions to perform the offset are determined and the offset is applied to the regions (Band Offset) or the offset is applied by considering the edge information of each pixel (Edge Offset). However, in one embodiment, the filter unit (150) may not apply filtering to the restoration block used for inter-screen prediction.

The adaptive loop filter (ALF) can be performed only when high efficiency is applied based on the value obtained by comparing the filtered restored image with the original image. After dividing the pixels included in the image into a predetermined group, one filter to be applied to the group is determined, and filtering can be performed differentially for each group. Information related to whether to apply the ALF can be transmitted by luminance signal for each coding unit (CU), and the shape and filter coefficient of the ALF filter to be applied can be different for each block. In addition, the ALF filter of the same shape (fixed shape) can be applied regardless of the characteristics of the target block.

The memory (155) can store the restoration block or image produced through the filter unit (150). The restoration block or image stored in the memory (155) can be provided to the inter-screen prediction unit (110) or the intra-screen prediction unit (115) that performs inter-screen prediction. The pixel values of the restoration blocks used in the intra-screen prediction unit (115) can be data to which the deblocking filter unit, the offset correction unit, and the adaptive loop filter unit are not applied.

FIG. 2 is a block diagram schematically illustrating an image decoding device according to one embodiment of the present invention. Referring to FIG. 2, an image decoding device (200) includes an entropy decoding unit (210), a reordering unit (215), an inverse quantization unit (220), an inverse transformation unit (225), an inter-screen prediction unit (230), an intra-screen prediction unit (235), a filter unit (240), and a memory (245).

When an image bitstream is input from an image encoding device, the input bitstream can be decoded by the reverse process of the procedure in which the image information is processed in the encoding device. For example, when a variable length coding (VLC, hereinafter referred to as “VLC”) such as CAVLC is used to perform entropy encoding in the image encoding device, the entropy decoding unit (210) can also perform entropy decoding by implementing the same VLC table as the VLC table used in the encoding device. In addition, when CABAC is used to perform entropy encoding in the encoding device, the entropy decoding unit (210) can perform entropy decoding using CABAC in response thereto.

The entropy decoding unit (210) provides information for generating a prediction block from among the decoded information to the inter-screen prediction unit (230) and the intra-screen prediction unit (235), and the residual value on which entropy decoding is performed in the entropy decoding unit can be input to the rearrangement unit (215).

The reordering unit (215) can reorder the bitstream that has been entropy decoded by the entropy decoding unit (210) based on the method used to reorder the video encoder. The reordering unit (215) can perform reordering by receiving information related to coefficient scanning performed by the encoding device and performing reverse scanning based on the scanning order performed by the encoding device.

The inverse quantization unit (220) can perform inverse quantization based on the quantization parameters provided by the encoding device and the coefficient values of the rearranged blocks. The inverse transform unit (225) can perform inverse DCT, inverse DST, or inverse KLT on the DCT, DST, or KLT performed by the transform unit of the encoding device for the quantization result performed by the image encoding device. The inverse transform can be performed based on the transmission unit or the image division unit determined by the encoding device. The transform unit of the encoding device can selectively perform DCT, DST, or KLT according to information such as a prediction method, the size of the current block, and the prediction direction, and the inverse transform unit (225) of the decoding device can perform inverse transform by determining an inverse transform method based on the transform information performed by the transform unit of the encoding device.

The prediction unit (230, 235) can generate a prediction block based on the information related to prediction block generation provided by the entropy decoding unit (210) and the previously decoded block and/or image information provided by the memory (245). The restoration block can be generated using the prediction block generated by the prediction unit (230, 235) and the residual block provided by the inverse transformation unit (225). The specific prediction method performed by the prediction unit (230, 235) can be the same as the prediction method performed by the prediction unit (110, 115) of the encoding device.

The prediction unit (230, 235) may include a prediction unit determination unit (not shown), an inter-screen prediction unit (230), and an intra-screen prediction unit (235). The prediction unit determination unit receives various information such as prediction unit information input from the entropy decoding unit (210), prediction mode information of an intra-screen prediction method, and motion prediction-related information of an inter-screen prediction method, and can distinguish a prediction block in a current coding block and determine whether the prediction block performs inter-screen prediction or intra-screen prediction.

The inter-screen prediction unit (230) can perform inter-screen prediction for the current prediction block based on information included in at least one image among the previous or subsequent images of the current image including the current prediction block, using information required for inter-screen prediction of the current prediction block provided by the image encoder.

Specifically, in inter-screen prediction, a reference image can be selected for the current block, and a reference block for the current block can be selected to generate a prediction block for the current block. At this time, in order to use the information of the reference image, information of surrounding blocks of the current image can be used. For example, a method such as skip mode, merge mode, and AMVP (Advanced Motion Vector Prediction) can be used to generate a prediction block for the current block based on the information of the surrounding blocks.

In AMVP mode, a list of predicted motion vectors can be constructed by selecting motion information candidates using temporally and spatially surrounding blocks of the current block. In addition, the motion vector of the current block can be decoded using index information and differential motion vectors (MVDs) for motion information candidates selected as predicted motion vectors of the current block received from the encoding device.

In addition, in the Merge mode, motion information candidates can be obtained as merge candidates by using temporally and spatially neighboring blocks of the current block. Among these, the motion vector of the current block can be obtained by using index information about the motion information candidates of the current block received from the encoding device. The motion vector candidates can be obtained as spatial motion vector candidates from spatial neighboring blocks of the current block or as temporal motion vector candidates from corresponding blocks included in the reference image of the current block.

Prediction blocks can be generated in units of samples less than an integer, such as 1/2 pixel sample units and 1/4 pixel sample units. In this case, motion vectors can also be expressed in units less than an integer pixel. For example, they can be expressed in units of 1/4 pixel for luminance pixels and in units of 1/8 pixel for chrominance pixels.

Motion information including motion vectors and reference image indices required for inter-screen prediction of the current block can be derived by checking skip flags, merge flags, etc. received from an encoding device and responding thereto.

The intra-screen prediction unit (235) can generate a prediction block based on pixel information in the current image. If the prediction unit is a prediction unit that has performed intra-screen prediction, intra-screen prediction can be performed based on intra-screen prediction mode information of the prediction unit provided by the image encoder. If the surrounding blocks of the above-mentioned prediction unit are blocks that have performed inter-screen prediction, that is, if the reference pixel is a pixel that has performed inter-screen prediction, the reference pixel included in the block that has performed inter-screen prediction can be replaced with reference pixel information of the surrounding blocks that have performed intra-screen prediction.

Additionally, the intra-screen prediction unit (235) may utilize the most probable intra-screen prediction mode (MPM) obtained from neighboring blocks to encode the intra-screen prediction mode. In one embodiment, the most probable intra-screen prediction mode may utilize the intra-screen prediction mode of a spatial neighboring block of the current block.

In one embodiment, the processing unit where prediction is performed in the on-screen prediction unit (235) and the processing unit where the prediction method and specific content are determined may be different from each other. For example, the prediction mode may be determined as the prediction unit and prediction may be performed as the prediction unit, or the prediction mode may be determined as the prediction unit and on-screen prediction may be performed as the conversion unit.

In this case, the prediction block (PU) can be determined in various sizes and shapes from the coding block (CU) that is no longer divided. For example, in the case of intra-picture prediction, the prediction block can have a size such as 2N x 2N or N x N (N is an integer), but the intra-picture prediction can also be performed with non-normal size shapes such as N x mN, mN x N, 2N x mN or mN x 2N (m is a fraction or an integer). In this case, the prediction unit of size N x N can also be set to be applied only in specific cases.

In addition, the transform block (TU) can also be determined in various sizes and shapes. For example, the transform block can have a size such as 2N x 2N or N x N (N is an integer), but can also perform intra-picture prediction not only in the regular size but also in non-regular size shapes such as N x mN, mN x N, 2N x mN or mN x 2N (m is a fraction or an integer). In this case, the prediction unit of size N x N can be set to be applied only in a specific case. In one embodiment, the transform block can be one of blocks having a square structure, a non-square structure, a square quad tree structure, a non-square quad tree structure, or a binary tree structure. In one embodiment, the size of the transform block can be determined within a range of predetermined maximum and minimum sizes. Additionally, a single transform block may be split into sub-transform blocks, in which case the sub-transform blocks may also be split into a square structure, a non-square structure, a square quad tree structure, a non-square quad tree structure, or a binary tree structure.

The intra-screen prediction unit (235) may include an AIS (Adaptive Intra Smoothing) filter unit, a reference pixel interpolation unit, and a DC filter unit. The AIS filter unit is a unit that performs filtering on the reference pixels of the current block and may determine and apply whether to apply the filter according to the prediction mode of the current prediction unit. AIS filtering may be performed on the reference pixels of the current block using the prediction mode and AIS filter information of the prediction unit provided by the image encoder. If the prediction mode of the current block is a mode that does not perform AIS filtering, the AIS filter unit may not be applied to the current block.

The reference pixel interpolation unit can generate a reference pixel of a pixel unit less than an integer value by interpolating the reference pixel when the prediction mode of the prediction unit is a prediction unit that performs prediction within the screen based on the sample value interpolated with the reference pixel. When the prediction mode of the current prediction unit is a prediction mode that generates a prediction block without interpolating the reference pixel, the reference pixel may not be interpolated. The DC filter unit can generate a prediction block through filtering when the prediction mode of the current block is the DC mode.

The restored block and/or image may be provided to the filter unit (240). The filter unit (240) may include a deblocking filter unit, an offset correction unit (Sample Adaptive Offset) and/or an adaptive loop filter unit for the restored block and/or image. The deblocking filter unit may receive information indicating whether a deblocking filter has been applied to a corresponding block or image from an image encoder, and information indicating whether a strong filter or a weak filter has been applied if the deblocking filter has been applied. The deblocking filter unit may receive information related to the deblocking filter provided from the image encoder, and perform deblocking filtering on the corresponding block from an image decoder.

The above offset correction unit can perform offset correction on the restored image based on the type of offset correction applied to the image during encoding, information on the offset value, etc. The above adaptive loop filter unit can be applied to each encoding unit based on information such as information on whether to apply the adaptive loop filter provided from the encoder, and coefficient information of the adaptive loop filter. Information related to the adaptive loop filter can be provided by being included in a specific parameter set.

The memory (245) can store a restored image or block so that it can be used as a reference image or reference block later, and can also provide the restored image to an output unit.

Although omitted for convenience of explanation in this specification, a bitstream input to a decoding device may be input to an entropy decoding unit through a parsing step. In addition, the entropy decoding unit may perform a parsing process.

In this specification, coding may be interpreted as encoding or decoding, and information may be understood to include all of values, parameters, coefficients, elements, flags, etc. 'Screen' or 'picture' generally means a unit representing one image of a specific time period, and 'slice', 'frame', etc. are units that constitute part of an image in the coding of an actual video signal, and may be used interchangeably with image if necessary.

'Pixel', 'pixel' or 'pel' represent the smallest unit that constitutes an image. Also, 'sample' can be used as a term representing the value of a specific pixel. Samples can be divided into luminance (Luma) and chroma (Chroma) components, but can generally be used as a term that includes all of them. In the above, the chroma component represents the difference between determined colors and is generally composed of Cb and Cr.

The term 'unit' refers to a basic unit of image processing, such as the encoding unit, prediction unit, or transformation unit described above, or a specific location of an image, and in some cases may be used interchangeably with terms such as 'block' or 'area'. In addition, a block may also be used as a term indicating a set of samples or transform coefficients consisting of M columns and N rows.

Figures 3 and 4 are for explaining the structure of a transform block according to a general method and a transform coefficient group for configuring a 16x16 transform block.

Referring to FIG. 3, one coding block (CB) may include a plurality of transform blocks (TB0, TB1, ..., TB12). The plurality of transform blocks may include transform blocks having various shapes and/or sizes. The transform block may include a square block and a non-square block, and the transform block may be one of blocks having a square quad tree structure, a non-square quad tree structure, or a binary tree structure.

Referring to FIG. 4, the transform block (10) may include at least one transform coefficient group (CG0, CG1, ..., CG15). For example, the transform block (10) may be a block having a size of 16x16, and the size of the transform coefficient group included in the transform block may be 4x4. That is, the transform block having a size of 16x16 may include 16 transform coefficient groups having a size of 4x4, and the index of the transform coefficient group may follow the transform coefficient scan order as shown in FIG. 4.

Figure 5 is for explaining a group of conversion coefficients according to a general method and a conversion scan method of the group of conversion coefficients.

Referring to FIG. 5, in general, the scan order of the transform coefficient group of the transform block (20) may be the same as the scan order of the transform coefficients. For example, if the transform block (20) has a size of 8x8, the size of the transform coefficient group is a block of a size of 4x4, and an up-right diagonal scan method is used for the transform block (20), the transform coefficient group applies the same scan method as the transform coefficients. As shown in FIG. 5, the transform coefficients included in the transform coefficient group CG3 at the lower right of the transform block (20) are scanned from the transform coefficients 15 to 0 using the up-right diagonal method, and then the transform coefficients included in the transform coefficient group CG2 at the upper right are scanned using the same method, and then the transform coefficients included in the transform coefficient group CG1 at the lower left and the transform coefficient group CG0 at the upper left are scanned using the same method.

Figures 6a to 6d are provided to explain various examples of a transform coefficient group according to a general method and a scanning method of the transform coefficient group. Figures 6a to 6c illustrate a scanning method of a transform coefficient group in an intra-screen prediction mode, and Figure 6d illustrates a scanning method of a transform coefficient group in an inter-screen prediction mode.

Referring to FIGS. 6a to 6c, for intra-screen prediction, an up-right diagonal scan (FIG. 6a) that scans from the lower right to the upper left, a horizontal scan (FIG. 6b) that scans from the right to the left and from the bottom to the top, and a vertical scan (FIG. 6c) that scans from the bottom to the top and from the right to the left can be used. Referring to FIG. 6d, for inter-screen prediction, only an up-right diagonal scan method can be used.

In one embodiment, a method of scanning a transform coefficient group in intra-screen prediction may be determined according to an intra-screen prediction mode. For example, when the intra-screen prediction mode is a horizontal prediction mode index of 6 to 14, a vertical scan method may be used to scan a transform coefficient group, when the intra-screen prediction mode is a vertical prediction mode index of 22 to 30, a horizontal scan method may be used, and for the remaining intra-screen prediction modes, an up-right diagonal scan method may be used.

Until recently, video coding has always considered a forward transform block as a transform block. Therefore, a transform coefficient group and a scanning method of transform coefficients within the transform coefficient group have also been designed to be suitable for a forward transform block. However, when a non-square transform block is used as a transform block, the coding efficiency may be reduced when applying the existing transform coefficient group and the scanning method of the transform coefficients. Therefore, a method of scanning a transform coefficient group that can improve coding efficiency according to an embodiment of the present invention will be described below with reference to FIGS. 7A to 12B.

FIGS. 7A and 7B illustrate examples of applying a general scan method to a conversion block according to one embodiment of the present invention.

Referring to FIG. 7a, if the current transform block TB1 (30a) is a non-square block and has a size of 8x16, when applying the existing method as a method for scanning the transform coefficient group and the transform coefficients, three scan methods can be selected. For example, among the illustrated examples of scanning the transform coefficient group by applying the existing three scan methods to the current transform block (30a), the transform coefficient group can be scanned by applying the up-right scan method, the vertical scan method, and the horizontal scan method from the left.

Referring to FIG. 7b, if the current transform block TB2 (30b) is a non-square block and has a size of 16x8, when applying the existing method as a method for scanning the transform coefficient group and the transform coefficients, three scan methods can be selected. For example, among the examples illustrating scanning the transform coefficient group by applying the existing three scan methods to the current transform block (30b), the transform coefficient group can be scanned by applying the up-right scan method, the vertical scan method, and the horizontal scan method from the left.

Figure 8 is an example of applying a general scan method to the transform coefficients of a 16x8 transform block.

Referring to Fig. 8, when applying the horizontal scan method to the current transform block TB2 (30b), the transform coefficients and the transform coefficient groups can be applied with the same scan method, the horizontal method. For example, the multiple transform coefficient groups including the multiple transform coefficients can be scanned for each transform coefficient group unit. After the transform coefficients included in the transform coefficient group located at the rightmost bottom among the transform blocks are scanned in the horizontal method, the transform coefficients included in the transform coefficient group located to the left of the rightmost bottom transform coefficient group can be scanned in the horizontal method. Afterwards, the transform coefficient group unit can also be scanned in the horizontal method in the same manner.

Through this transformation process, most of the energy of the residual signal can be gathered in the DC region at the upper left. Therefore, for the efficiency of entropy coding, it may be efficient for the transform coefficients and/or transform coefficient groups of the low-frequency region to have indices indicating a scan order of small values. However, when applying the scan order of the general transform coefficient groups as shown in FIGS. 7a to 8 to the non-square transform block, the transform coefficient groups of the high-frequency region may be coded before the transform coefficient groups of the low-frequency region, which may result in a decrease in coding efficiency.

Therefore, a method for scanning transform scan coefficients according to one embodiment of the present invention may include a method of dividing a transform block into a transform region, which is an upper region including a plurality of transform scan coefficients, and scanning the transform scan coefficients for each of the divided transform regions.

FIGS. 9 and 10 are flowcharts and devices illustrating a method for scanning a group of conversion coefficients according to one embodiment of the present invention.

Referring to FIGS. 9 and 10, the transform unit may obtain transform area information indicating a transform area that divides a plurality of transform coefficient groups included in a transform block into at least one or more sections in order to scan the transform coefficient group (S10). The transform block may have various sizes and/or shapes. In one embodiment, the transform block may be a non-square-shaped transform block.

The above transform domain information can divide the transform block into at least one region, and each transform domain can include a plurality of transform coefficient groups. It goes without saying that the transform coefficient group includes a plurality of transform coefficients. In addition, the transform domain information can be information received from an encoder. For example, the transform domain information can be obtained from at least one of a sequence parameter set (SPS) and a slice header, and the present invention is not limited thereto, and the present invention does not limit the form and level of syntax included in it, and any information received from an encoder may be sufficient.

In one embodiment, the transform region information can be obtained by a method determined by the decoding device. For example, the transform region information can be obtained by calculating the horizontal and vertical lengths of the transform region based on the horizontal and vertical lengths of the transform block, thereby determining the size and number of the transform regions. Alternatively, the transform region information can also determine the size and number of the transform regions by dividing the smaller length among the horizontal and vertical lengths of the transform block by the block size of the transform coefficient group. The horizontal and vertical lengths, shape, and number of the transform regions indicated by the transform region information can follow a method determined by the decoding device, and are not limited to the examples described above.

Thereafter, the transform coefficient group scan unit (50) can scan multiple transform coefficient groups within at least one transform area divided based on the transform area information. The transform coefficient group scan unit (50) can include a first transform area scan unit (51) and a second transform area scan unit (52) to scan the transform coefficient groups of the divided transform areas. The transform area scan unit is not limited to the first transform area scan unit (51) and the second transform area scan unit (52), and the number of transform blocks can be included corresponding to the number of divided transform areas.

First, the first transformation area scan unit (51) can scan a plurality of transformation coefficient groups included in the first transformation area among the plurality of transformation areas divided based on the transformation area information (S20). Thereafter, the second transformation area scan unit (52) can scan a plurality of transformation coefficient groups included in the second transformation area. If three or more transformation area scan units are included, the transformation coefficient groups included in the transformation areas will be scanned in sequence.

In one embodiment, the first transform domain scan unit (51) may include more transform coefficient groups in the low frequency domain than the second transform domain scan unit (52). In this way, the method for scanning transform coefficient groups of the present invention determines the scan order so that the transform coefficient groups in the low frequency domain are scanned before the transform coefficient groups in the high frequency domain, thereby resolving the disadvantage that the transform coefficient groups in the high frequency domain are coded and transmitted first and the transform coefficient groups in the low frequency domain have a large scan order index, thereby lowering the coding efficiency.

In addition, in one embodiment, it is possible to first determine whether the transform block is a non-square block before acquiring transform domain information. When the transform block is a non-square block, it is possible to frequently cause the transform coefficient group corresponding to the high-frequency region to be scanned earlier than the transform coefficient group corresponding to the low-frequency region, thereby lowering the coding efficiency. Therefore, it is possible to first determine whether the current transform block is a non-square block before acquiring transform domain information.

In one embodiment, various methods may be adopted to determine whether the transform block is a non-square block. For example, it may be determined whether the transform block is a non-square block by comparing the horizontal and vertical lengths of the transform block. Alternatively, information about the size and shape of the transform block may be received from an encoding device or may be determined based on one or more of the segmentation information, direction information, α, β, and pixel information of the transform block acquired by a decoding device.

In addition, it may be determined based on the transform block type information indicating the type of the transform block. The transform block type information may be received from the encoding device, but may also be calculated by the decoding device based on one or more of the segmentation information, direction information, pixel information, and horizontal and vertical length information of the transform block. In this way, when the transform block is determined to be a non-square block, the transform coefficient group included in the transform area of each transform area of the transform block can be scanned by the method described above with reference to FIGS. 9 and 10.

FIGS. 11A and 11B illustrate a method of scanning a transform coefficient group for a non-square transform block according to one embodiment of the present invention.

Referring to FIG. 11A, the non-square transform block (60a, 60b) of the present invention may have a horizontal length (A) and a vertical length (B). The non-square transform block (60a, 60b) having a size of AxB includes a plurality of transform coefficient groups and may be divided into transform block regions of a size of αxβ. The α and β represent the number of transform coefficient groups included in the transform block. That is, the region of the size of αxβ may represent a region having α transform coefficient groups in the horizontal direction and β transform coefficient groups in the vertical direction. In one embodiment, the transform region information may include information about the α and β. In addition, the transform region information may include information indicating the horizontal and vertical sizes of the transform region. For example, if a non-square transform block (60a) has a size of 8x16, αxβ representing the structure of the transform area is 2x2, and the size of the transform area dividing the transform block (60a) can be 8x8.

Such transform domain information can be derived from upper parameters or a previous decoding process, and simply, can be derived from a number obtained by dividing the smaller of the width and height of a non-square transform block by the size of the transform coefficient block. However, the method of obtaining transform domain information in the present invention is not limited thereto.

Referring to FIG. 11b, a transform block (60a, 60b) divided into a plurality of transform regions can scan a transform coefficient group by applying a scan method determined from an upper parameter or an upper process to each transform region. For example, if a transform block (60b) having a size of 16x8 is divided into transform regions (αxβ = 2x2) having a size of 8x8, and the transform region and the transform coefficient group are scanned by the up-right scan method, the transform coefficient group in CG Region 1 can be scanned first by the up-right scan method, and then the transform coefficient group in CG Region 2 can be scanned by the up-right scan method.

FIGS. 12A to 13D illustrate various methods of scanning a transform coefficient group for a non-square transform block according to one embodiment of the present invention.

Referring to FIGS. 12A to 12D, a transform coefficient group when a transform block (70) is divided into transform regions having small side lengths of the transform block can be scanned in various ways. As shown in FIG. 12A, when the transform block (70) has a size of 16x32, each of the transform regions CG Region 0 and CG Region 1 (71, 72) can have a size of 16x16. Here, α and β representing the sizes of the transform regions in the horizontal and vertical directions can be α=β=4.

In one embodiment, the transform block (70) may sequentially scan the transform coefficient groups included in each transform region for each transform region. For example, as shown in FIG. 12b, when the transform block (70) is scanned by the up-right scan method, the 17th transform coefficient group (CG 16) may be sequentially scanned from the 32nd transform coefficient group (CG 31) included in the second transform region (CG Region 1) at the bottom, and then the 1st transform coefficient group (CG 0) may be sequentially scanned from the 16th transform coefficient group (CG 15) included in the first transform region (CG Region 0). In addition, when the transform block is divided into two transform regions and the vertical scan method and the horizontal scan method are applied to the transform block, the case is the same as shown in FIGS. 12c and 12d.

Referring to FIGS. 13A to 13D, a group of transform coefficients when a transform block (80) is divided into transform regions having small side lengths of the transform block (80) can be scanned in various ways. As shown in FIG. 13A, when the transform block (80) has a size of 32x16, each of the transform regions CG Region 0 and CG Region 1 (81, 82) can have a size of 16x16. Here, α and β representing the number of transform regions in the horizontal and vertical directions can be α=β=4.

In one embodiment, the transform block (80) may sequentially scan the transform coefficient groups included in each transform region for each transform region. For example, as shown in FIG. 13b, when the transform block (80) is scanned in an up-right scan manner, the 17th transform coefficient group (CG 16) from the 32nd transform coefficient group (CG 31) included in the second transform region (82) on the right may be sequentially scanned in an up-right manner, and then the 1st transform coefficient group (CG 0) from the 16th transform coefficient group (CG 15) included in the first transform region (CG Region 0) may be sequentially scanned. In addition, as shown in FIG. 13c, when the transform block (80) is scanned in the vertical scan method, the 17th transform coefficient group (CG 16) from the 32nd transform coefficient group (CG 31) included in the second transform region (82) on the right may be scanned in sequence in the vertical manner, and then the 1st transform coefficient group (CG 0) may be scanned in sequence from the 16th transform coefficient group (CG 15) included in the first transform region (CG Region 0). The case where the transform block is divided into two transform regions and the horizontal scan method is applied to the transform block is the same as shown in FIG. 13d.

According to the method of dividing a transform block into at least one transform area including a plurality of transform coefficient groups and scanning each transform area, the transform coefficient group of a low-frequency area is scanned and transmitted before the transform coefficient group of a high-frequency area, so that coding efficiency can be increased.

It will be apparent to those skilled in the art that the present invention described above is not limited to the above-described embodiments and the attached drawings, and that various substitutions, modifications, and changes are possible within the scope that does not depart from the technical spirit of the present invention.

Claims (6)

A step of receiving a bitstream including transform area information included in a transform block and indicating transform areas into which the transform block is divided in at least two or more horizontal or vertical directions;
A step of dividing the transformation block into at least two transformation areas using the transformation area information;
A step of obtaining a scanning method for each of the divided transformation areas from the transformation area information;
A step of obtaining transform coefficients by scanning a first plurality of transform coefficient groups included in a first transform area of a low-frequency area using the above scanning method; and
A step of obtaining transform coefficients by scanning a second plurality of transform coefficient groups included in a second transform area of a high-frequency area using the above scanning method,
The first plurality of transform coefficient groups are scanned before the second plurality of transform coefficient groups,
The first scanning method for scanning the first plurality of transformation coefficient groups and the second scanning method for scanning the second plurality of transformation coefficient groups are different from each other,
The above transformation coefficient group includes multiple transformation coefficients,
A method for decoding a video signal received from an encoder, wherein the above transformation area information is determined from at least one of a sequence parameter set (SPS) and a slice header. In paragraph 1,
A method for decoding a video signal, characterized in that it further comprises a step of determining the type of the above transformation block. In the second paragraph,
A method for decoding a video signal, characterized in that the step of determining the type of the above transformation block is performed based on the horizontal length and vertical length of the above transformation block. A transform region division unit that receives a bitstream including transform region information indicating transform regions into which the transform block is divided in at least two or more horizontal or vertical directions, and divides the transform block into the at least two or more transform regions using the transform region information; and
A transform coefficient scanning unit is included that obtains a scanning method of each of the divided transform areas from the transform area information, obtains transform coefficients by scanning a first plurality of transform coefficient groups included in a first transform area of a low-frequency area according to the scanning method, and obtains transform coefficients by scanning a second plurality of transform coefficient groups included in a second transform area of a high-frequency area.
The first plurality of transform coefficient groups are scanned before the second plurality of transform coefficient groups,
The first scanning method for scanning the first plurality of transformation coefficient groups and the second scanning method for scanning the second plurality of transformation coefficient groups are different from each other,
The above transformation coefficient group includes multiple transformation coefficients,
A decoding device for a video signal received from an encoder, wherein the above transformation area information is determined from at least one of a sequence parameter set (SPS) and a slice header. In paragraph 4,
A video signal decoding device, characterized in that the bitstream further includes information about the type of the transform block. In paragraph 5,
Information about the type of the above transformation block is based on the horizontal and vertical lengths of the above transformation block.
A video signal decoding device, characterized in that the above transformation region division unit determines the type of the transformation block based on information about the type of the transformation block.

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