Image encoding / decoding method and device

Abstract

The present invention relates to an image encoding / decoding method and device. The image decoding method according to an embodiment of the present invention includes the steps of: deriving a motion vector prediction value of a current block; acquiring information on a motion vector difference of the current block; deriving the motion vector difference of the current block on the basis of the information on the motion vector difference; and deriving a motion vector of the current block on the basis of the motion vector prediction value and the motion vector difference. The information on the motion vector difference of the current block may include an index indicating a region including at least one combination of the value of an x component and the value of a y component of the motion vector difference of the current block.

Description

Video encoding / decoding method and device

[0001] The present invention relates to a video encoding / decoding method and device, and more specifically, to a video encoding / decoding method and device that improves the encoding efficiency of motion vector differences.

[0002] Recently, the demand for multimedia data, such as video, has been rapidly increasing. In particular, the demand for high-resolution, high-quality video, such as HD (High Definition) and UHD (Ultra High Definition) video, is growing across a wide range of applications. High-resolution, high-quality video data typically requires significantly more data volume than conventional video data. Consequently, the transmission and storage costs for storing and / or transmitting high-resolution, high-quality video data increase compared to conventional video data.

[0003] To solve these problems, high-efficiency image encoding / decoding technology for images with higher resolution and quality is required.

[0004] In order to encode an image, various techniques are used, such as an intra prediction technique that predicts the pixel values ​​included in the current picture using pixel information in the current picture, an intra prediction technique that predicts the pixel values ​​included in the current picture from the pictures before or after the current picture, a transform and quantization technique for compressing the energy of the residual signal, which is the difference between the predicted signal and the original signal, and an entropy coding technique that assigns short codes to values ​​with high appearance frequencies and long codes to values ​​with low appearance frequencies. In addition, various tools are being developed to implement each technique in order to improve the efficiency of image coding. In addition, in order to decode an encoded image, the image can be restored and reproduced through an image decoding technique that uses a technique and tools corresponding to the image coding technique.

[0005] Using these video encoding and decoding technologies, video data can be effectively compressed, transmitted, stored, and played back.

[0006] The present disclosure aims to provide a video encoding / decoding method and device that improves the inefficiency of the encoding process of motion vector differences and enhances compression efficiency.

[0007] In addition, the present disclosure aims to provide a video encoding / decoding method and device that improves compression efficiency by improving a process of encoding information regarding motion vector differences.

[0008] The technical challenges to be achieved through this disclosure are not limited to the technical challenges mentioned above. Furthermore, other technical challenges not mentioned in this disclosure will be readily apparent to those skilled in the art from this disclosure.

[0009] A video decoding method according to one embodiment of the present invention includes the steps of deriving a motion vector prediction value of a current block, obtaining information about a motion vector difference of the current block, deriving a motion vector difference of the current block based on the information about the motion vector difference, and deriving a motion vector of the current block based on the motion vector prediction value and the motion vector difference, wherein the information about the motion vector difference of the current block may include an index indicating an area including at least one combination of a value of an x ​​component and a value of a y component of the motion vector difference of the current block.

[0010] In the above image decoding method, the area including at least one combination can be defined by a combination of a range of an x ​​component and a range of a y component of a motion vector difference.

[0011] In the above image decoding method, the index can indicate one area among a plurality of areas including a combination of different x-component ranges and y-component ranges of motion vector differences.

[0012] In the above image decoding method, the information regarding the motion vector difference of the current block may further include information indicating the difference between the area indicated by the index and the motion vector difference of the current block.

[0013] In the above image decoding method, an area including at least one combination can be defined by a linear function of the x component and the y component of the motion vector difference.

[0014] In the above image decoding method, the index can indicate one area among a plurality of areas defined by different linear functions.

[0015] In the above image decoding method, the information regarding the motion vector difference of the current block may further include information indicating a value of one of the x component and the y component of the motion vector difference of the current block.

[0016] In the above image decoding method, the information regarding the motion vector difference of the current block may further include information indicating the sign of the x component of the motion vector difference of the current block and the y sign of the component of the motion vector difference of the current block.

[0017] In the above image decoding method, the area including at least one combination can be defined by a linear function of the absolute value of the x component and the absolute value of the y component of the motion vector difference.

[0018] In the above image decoding method, the information regarding the motion vector difference of the current block may further include information indicating the absolute value of one of the x component and the y component of the motion vector difference of the current block.

[0019] In the above image decoding method, the information regarding the motion vector difference of the current block may further include information indicating the sign of the x component of the motion vector difference of the current block, and information indicating the sign of the y component of the motion vector difference of the current block.

[0020] A video encoding method according to one embodiment of the present invention includes the steps of deriving a motion vector prediction value of a current block, obtaining information about a motion vector difference of the current block, deriving a motion vector difference of the current block based on the information about the motion vector difference, and deriving a motion vector of the current block based on the motion vector prediction value and the motion vector difference, wherein the information about the motion vector difference of the current block may include an index indicating an area including at least one combination of a value of an x ​​component and a value of a y component of the motion vector difference of the current block.

[0021] A non-transitory computer-readable recording medium storing a bitstream generated by an image encoding method according to one embodiment of the present invention comprises the steps of: deriving a motion vector prediction value of a current block; obtaining information about a motion vector difference of the current block; deriving a motion vector difference of the current block based on the information about the motion vector difference; and deriving a motion vector of the current block based on the motion vector prediction value and the motion vector difference, wherein the information about the motion vector difference of the current block includes an index indicating an area including at least one combination of an x ​​component value and a y component value of the motion vector difference of the current block.

[0022] A method for transmitting a bitstream generated by a video encoding method according to one embodiment of the present invention comprises the steps of transmitting the bitstream, deriving a motion vector prediction value of a current block, obtaining information about a motion vector difference of the current block, deriving a motion vector difference of the current block based on the information about the motion vector difference, and deriving a motion vector of the current block based on the motion vector prediction value and the motion vector difference, wherein the information about the motion vector difference of the current block includes an index indicating an area including at least one combination of a value of an x ​​component and a value of a y component of the motion vector difference of the current block.

[0023] According to the present invention, a video encoding / decoding method and device can be provided that improve compression efficiency by improving the inefficiency of the encoding process of motion vector differences.

[0024] In addition, according to the present invention, a recording medium storing a bitstream generated by the image encoding method or device of the present invention can be provided.

[0025] The effects that can be obtained from the present invention are not limited to the effects mentioned above, and other effects not mentioned can be clearly understood by a person having ordinary skill in the art to which the present invention belongs from the description below.

[0026] FIG. 1 is a block diagram showing an image encoding device according to one embodiment of the present invention.

[0027] FIG. 2 is a block diagram showing an image decoding device according to one embodiment of the present invention.

[0028] FIG. 3 is a diagram schematically showing a video coding system to which the present invention can be applied.

[0029] FIG. 4 is a drawing exemplarily showing a content streaming system to which an embodiment according to the present invention can be applied.

[0030] FIG. 5 is a diagram illustrating a predetermined area for encoding a motion vector difference according to one embodiment of the present invention.

[0031] FIG. 6 is a diagram illustrating a predetermined area for encoding a motion vector difference according to one embodiment of the present invention.

[0032] FIG. 7 is a diagram illustrating a predetermined area for encoding a motion vector difference according to one embodiment of the present invention.

[0033] FIG. 8 is a diagram illustrating a predetermined area for encoding a motion vector difference according to one embodiment of the present invention.

[0034] FIG. 9 is a diagram illustrating a predetermined area for encoding a motion vector difference according to one embodiment of the present invention.

[0035] FIG. 10 is a diagram illustrating a plurality of points for encoding a motion vector difference according to one embodiment of the present invention.

[0036] FIG. 11 is a diagram illustrating a plurality of linear regions for encoding a motion vector difference according to one embodiment of the present invention.

[0037] FIG. 12 is a diagram illustrating a plurality of linear regions for encoding a motion vector difference according to one embodiment of the present invention.

[0038] FIG. 13 is a diagram illustrating a plurality of areas for encoding a motion vector difference according to one embodiment of the present invention.

[0039] FIG. 14 is a diagram illustrating a plurality of areas for encoding a motion vector difference according to one embodiment of the present invention.

[0040] FIG. 15 is a diagram illustrating a plurality of areas for encoding a motion vector difference according to one embodiment of the present invention.

[0041] FIG. 16 is a diagram illustrating a plurality of areas for encoding a motion vector difference according to one embodiment of the present invention.

[0042] FIG. 17 is a diagram illustrating a plurality of areas for encoding a motion vector difference according to one embodiment of the present invention.

[0043] FIG. 18 is a flowchart illustrating a method for decoding an image using information indicating an area including a motion vector difference according to an embodiment of the present disclosure.

[0044] The present invention is susceptible to various modifications and embodiments. Specific embodiments are illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, but rather to encompass all modifications, equivalents, and alternatives falling within the spirit and technical scope of the present invention. Throughout the description of each drawing, similar reference numerals have been used to designate similar components.

[0045] While terms such as "first" and "second" may be used to describe various components, these components should not be limited by these terms. These terms are used solely to distinguish one component from another. For example, without departing from the scope of the present invention, a first component may be referred to as a "second component," and similarly, a second component may also be referred to as a "first component." The term "and / or" includes a combination of multiple related items described herein or any of multiple related items described herein.

[0046] When a component is referred to as being "connected" or "connected" to another component, it should be understood that it may be directly connected or connected to that other component, but that there may be other components intervening. Conversely, when a component is referred to as being "directly connected" or "connected" to another component, it should be understood that there are no other components intervening.

[0047] The terminology used in this application is only used to describe specific embodiments and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this application, it should be understood that the terms "comprise" or "have" indicate the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, but do not exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0048] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings. Hereinafter, identical components in the drawings will be designated by the same reference numerals, and redundant descriptions of identical components will be omitted.

[0049] FIG. 1 is a block diagram showing an image encoding device according to one embodiment of the present invention.

[0050] Referring to FIG. 1, an image encoding device (100) may include an image segmentation unit (101), an intra prediction unit (102), an inter prediction unit (103), a subtraction unit (104), a transformation unit (105), a quantization unit (106), an entropy encoding unit (107), an inverse quantization unit (108), an inverse transformation unit (109), an addition unit (110), a filter unit (111), and a memory (112).

[0051] 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 component. 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 one component may be divided into multiple components to perform a function, and such integrated and separate embodiments of each component are also included in the scope of the present invention as long as they do not deviate from the essence of the present invention.

[0052] Additionally, some components may not be essential components that perform essential functions of the present invention, but may be optional components merely used to enhance performance. The present invention may be implemented by including only components essential to implementing the essence of the present invention, excluding components used solely for performance enhancement. A structure that includes only essential components, excluding optional components used solely for performance enhancement, is also within the scope of the present invention.

[0053] The image segmentation unit (101) can divide the input image into at least one block. At this time, the input image or frame can be divided into tiles. Then, the tiles are divided into super blocks having a predetermined size, and each super block can be divided into blocks. The image segmentation unit (101) can recursively divide the super block into blocks. Here, the super block can be divided into two or four vertically or horizontally, or recursively divided into four. Alternatively, the super block can be divided once in each of the vertical and horizontal directions to be divided into three blocks. In addition, the image segmentation unit (101) can divide the block into units of transform blocks, which are units of transformation and / or prediction.

[0054] The prediction unit (102, 103) may include an intra-prediction unit (102) that performs intra-prediction and an inter-prediction unit (103) that performs inter-prediction. The prediction unit (102, 103) may determine whether to use intra-prediction or inter-prediction for a prediction unit. In addition, the prediction unit (102, 103) may determine specific information (e.g., intra-prediction mode, inter-prediction mode, motion vector, reference picture, etc.) according to the determined prediction method. At this time, the processing unit where the prediction is performed and the processing unit where the prediction method and specific contents are determined may be different. For example, the prediction unit (102, 103) may determine the prediction method and prediction mode for each prediction unit, and perform prediction according to the transformation unit.

[0055] In another embodiment, the prediction unit may encode the input image using a third mode (e.g., intra block copy (IBC), Palette mode, etc.) other than the intra mode and the inter mode. However, if the third mode has functional characteristics similar to the intra mode or the inter mode, the third mode may be classified as the intra mode or the inter mode. In the present disclosure, the third mode will be described only when a specific description thereof is required.

[0056] The intra prediction unit (102) can generate a prediction block of the current block based on the intra prediction mode of the current block and reference pixel information around the current block, which is pixel information within the current picture. If a neighboring block of the current block is predicted by inter prediction, the reference pixels included in the inter-predicted neighboring block can be replaced with reference pixels within another neighboring block that has been intra-predicted. That is, if a reference pixel is not available, the intra prediction unit (102) can perform intra prediction of the current block by replacing the unavailable reference pixel with at least one reference pixel among the available reference pixels.

[0057] Intra prediction modes used for intra prediction may include a directional prediction mode that uses reference pixel information according to the prediction direction, a non-directional mode that does not use directional information, a recursive intra prediction (RIP), and a Paeth intra prediction mode. In addition, the mode for predicting luminance information and the mode for predicting chrominance information may be different, and the intra prediction mode information of the luminance component block or the predicted luminance signal information may be utilized to predict chrominance information.

[0058] The intra prediction unit (102) may perform filtering on a reference sample or a prediction pixel. According to one embodiment, the intra prediction unit (102) may perform filtering on a reference sample according to a prediction mode, a size, and / or a shape of a current prediction unit, and may generate a prediction sample using the filtered reference sample. According to another embodiment, the intra prediction unit (102) may generate a prediction sample, and perform filtering on the prediction sample according to a prediction mode, a size, and / or a shape of a current prediction unit, to generate a filtered prediction sample. The intra prediction unit (102) may determine whether to perform filtering and / or the strength of the filtering based on at least one of a prediction mode, a size, a shape, and an encoding parameter of the current prediction unit.

[0059] The inter prediction unit (103) generates a prediction block using the previously restored reference image stored in the memory (112), the inter block mode, the inter prediction mode, and the motion information. Here, inter prediction may mean motion prediction or motion compensation.

[0060] The motion information may include, for example, motion vector stack information including motion vector candidates, reference picture information, a reference picture list indicator, motion compensation mode information, etc. Here, the motion vector candidates may be motion vectors obtained as a result of performing spatial motion vector prediction and temporal motion vector prediction. Spatial motion vector prediction and temporal motion vector prediction may be performed dynamically.

[0061] The inter prediction unit (103) performs motion vector prediction (MVP) to perform motion prediction and / or motion compensation, and can perform motion prediction and / or motion compensation for the prediction unit by applying a simple inter prediction mode, an Overlapped Block Motion Compensation (OBMC), and a local warp mode that uses motion information modified based on an affine model to the encoding unit.

[0062] Alternatively, the inter prediction unit (103) may perform motion prediction and / or motion compensation for the prediction unit by applying a compound prediction mode that synthesizes different prediction values. For example, the inter prediction unit (103) may perform motion prediction and / or motion compensation for the prediction unit by applying compound wedge prediction, frame distance based compound prediction, inter-intra prediction, etc.

[0063] A residual block containing residual information, which is the difference between the prediction unit generated in the prediction unit (102, 103) and the original block of the prediction unit, can be generated. The generated residual block can be input to the transformation unit (130) and transformed.

[0064] The subtraction unit (104) subtracts the block to be encoded and the prediction block generated from the intra prediction unit (102) or inter prediction unit (103) to generate a residual block of the current block. The residual (residual block) between the generated prediction block and the original block can be input to the transformation unit (105).

[0065] Additionally, the prediction mode information, motion vector information, etc. used for prediction can be encoded together with the residual value in the entropy encoding unit (107) and transmitted to the decoder. When using a specific encoding mode, it is also possible to encode the original block as is and transmit it to the decoding unit without generating a prediction block through the prediction unit (102, 103).

[0066] The transformation unit (105) can perform a transformation on a residual block including residual data to generate and output a transform coefficient. Here, the transform coefficient may be a coefficient value generated by performing a transformation on the residual block. If residual data does not exist, the transformation unit (105) may omit the transformation.

[0067] The transformation unit (105) can determine a transformation type and a transformation kernel based on at least one of coding parameters such as the size, color component, and prediction mode of the transformation block, and perform transformation on the transformation block using the determined transformation type and transformation kernel.

[0068] According to one embodiment, the transform unit (105) can perform the transform using a transform type and transform kernel according to at least one of DCT (Discrete Cosine Transform), ADST (Asymmetric Discrete Sine Transform), IDTX (Identity Transform), and WHT (Walsh Hadamard Transform).

[0069] The quantization unit (106) can quantize the transform coefficients or residual signals converted to the frequency domain by the transform unit (105) according to a quantization parameter (QP). The quantization parameter can vary depending on the block or the importance of the image. The value produced by the quantization unit (106) can be provided to the dequantization unit (108) and the entropy encoding unit (107).

[0070] The above transformation unit (105) and / or quantization unit (106) may be optionally included in the image encoding device (100). That is, the image encoding device (100) may encode the residual block by performing at least one of transformation or quantization on the residual data of the residual block, or by skipping both transformation and quantization. Even if neither transformation nor quantization is performed in the image encoding device (100), or neither transformation nor quantization is performed, a block that is input to the entropy encoding unit (107) is typically referred to as a transformation block.

[0071] The entropy encoding unit (107) can generate and output a bitstream by performing entropy encoding according to a probability distribution on values ​​output by the quantization unit (106), coding parameter values ​​output during the encoding process, information for decoding an image, etc. Here, the information for decoding an image may include syntax elements, etc.

[0072] Coding parameters may include information (flags, indices, etc.) encoded in an encoding device (100) and signaled to a decoding device (200), such as syntax elements, as well as information derived during an encoding process or a decoding process, and may mean information required when encoding or decoding an image.

[0073] The entropy encoding unit (107) can encode various information such as coefficient information of a transform block, block type information, prediction mode information, division unit information, prediction unit information, transmission unit information, motion vector information, reference frame information, block interpolation information, and filtering information. The entropy encoding unit (107) can apply arithmetic coding to multiple symbols. In addition, the entropy encoding unit (107) can encode coefficients based on multiple levels. Here, the entropy encoding unit (107) can use an exponential Golomb coding method.

[0074] The inverse quantization unit (108) and the inverse transformation unit (109) can inverse quantize the values ​​quantized in the quantization unit (106) and inversely transform the values ​​transformed in the transformation unit (105). The residual values ​​generated in the inverse quantization unit (108) and the inverse transformation unit (109) can be combined with the prediction units predicted through the motion estimation unit, motion compensation unit, and intra prediction unit (102) included in the prediction unit (102, 103) to generate a reconstructed block. The addition unit (110) adds the prediction blocks generated in the prediction units (102, 103) and the residual blocks generated through the inverse transformation unit (109) to generate a reconstructed block.

[0075] The filter unit (111) can apply all or part of a filtering technique, such as an edge loop filter, an adaptive loop filter (ALF), a constrained directional enhancement filter (CDEF), or a loop restoration filter, to a restored sample, restored block, or restored image.

[0076] The memory (112) can store a restored block or picture produced through the filter unit (111). The memory (112) can include a reference picture buffer. In addition, the restored block or picture stored in the memory (112) can be provided to the prediction unit (102, 103) when performing inter prediction.

[0077] Next, an image decoding device according to one embodiment of the present invention will be described with reference to the drawings.

[0078] FIG. 2 is a block diagram showing an image decoding device (200) according to one embodiment of the present invention.

[0079] Referring to FIG. 2, the image decoding device (200) may include an entropy decoding unit (201), an inverse quantization unit (202), an inverse transformation unit (203), a prediction unit (204, 205), an addition unit (206), a filter unit (207), and a memory (208).

[0080] The image decoding device (200) can receive a bitstream output by the image encoding device (100). The image decoding device (200) can receive a bitstream stored in a computer-readable recording medium, or can receive a bitstream streamed through a wired / wireless transmission medium. The image decoding device (200) can decode the bitstream to generate a restored image or a decoded image, and can output the restored image or the decoded image.

[0081] The entropy decoding unit (201) can generate symbols by performing entropy decoding according to a probability distribution for the bitstream. The generated symbols may include symbols in the form of quantized levels. Here, the entropy decoding method may be the reverse process of the entropy encoding method described above.

[0082] The entropy decoding unit (201) can change a one-dimensional vector-shaped coefficient into a two-dimensional block-shaped coefficient through a transform coefficient scanning method to decode a transform coefficient level (quantized level).

[0083] The entropy decoding unit (201) can perform entropy decoding in a procedure opposite to that of the entropy encoding unit (107) of the video encoding device (100). For example, the entropy decoding unit (201) can perform entropy decoding by applying a method such as multi-level arithmetic encoding or exponential Golomb corresponding to the method performed in the video encoder.

[0084] The entropy decoding unit (201) can decode and obtain various information such as coefficient information of the transform block as described above, block type information, prediction mode information, division unit information, prediction unit information, transmission unit information, motion vector information, reference frame information, block interpolation information, and filtering information.

[0085] The inverse quantization unit (202) performs inverse quantization on the quantized transform block to generate a transform block. The inverse quantization unit (202) operates substantially the same as the inverse quantization unit (108) of FIG. 1.

[0086] The inverse transform unit (203) performs an inverse transform on the transform block to generate a residual block. At this time, the transform method can be determined based on information regarding the prediction method (inter or intra prediction), the size and / or shape of the block, the intra prediction mode, etc. The inverse transform unit (203) operates substantially the same as the inverse transform unit (109) of FIG. 1.

[0087] The prediction unit (204, 205) can generate a prediction block based on the prediction block generation related information provided by the entropy decoding unit (201) and the previously decoded block or picture information provided by the memory (208).

[0088] The prediction unit (204, 205) may include an intra prediction unit (204) and an inter prediction unit (205). The prediction unit (204, 205) may receive various information such as prediction unit information input from the entropy decoding unit (201), prediction mode information of the intra prediction method, and motion prediction-related information of the inter prediction method, and may distinguish a prediction unit from a current encoding unit and determine a prediction mode of the prediction unit.

[0089] The intra prediction unit (204) can generate a prediction block of the current block based on the intra prediction mode of the current block and reference pixel information around the current block, which is pixel information within the current picture.

[0090] The intra prediction mode used for intra prediction may be one of the directional prediction mode, non-directional mode, RIP, and Paeth intra prediction modes. Additionally, the mode for predicting luminance information may be different from the mode for predicting chrominance information, and the intra prediction mode information of the luminance component block or the predicted luminance signal information may be utilized to predict chrominance information.

[0091] According to one embodiment, the intra prediction unit (204) may perform filtering on a reference sample and generate a prediction sample using the filtered reference sample. Alternatively, the intra prediction unit (204) may generate a prediction sample and perform filtering on the prediction sample to generate a filtered prediction sample. Here, whether to apply filtering and the strength of the filtering may be determined based on at least one of the prediction mode, size, shape, and encoding parameters of the current prediction unit.

[0092] The intra prediction unit (204) operates substantially the same as the intra prediction unit (102) of FIG. 1.

[0093] The inter prediction unit (205) may perform inter prediction on the current prediction unit based on information included in at least one of the previous or subsequent pictures of the current picture including the current prediction unit, using information required for inter prediction of the current prediction unit provided by the image encoding device (100). Alternatively, inter prediction may be performed based on information of a pre-restored portion of the current picture including the current prediction unit. The inter prediction unit (205) generates a prediction block using a reference image, an inter prediction mode, and motion information. Here, inter prediction may mean motion compensation.

[0094] The motion information may include, for example, motion vector stack information including motion vector candidates, reference picture information, reference picture list indicator, motion compensation mode information, etc.

[0095] The inter prediction unit (205) can operate substantially the same as the inter prediction unit (103) of FIG. 1.

[0096] The addition unit (206) adds the prediction block generated by the intra prediction unit (204) or inter prediction unit (205) and the residual block generated by the inverse transformation unit (203) to generate a restored block. It operates substantially the same as the addition unit (110) of Fig. 1.

[0097] The filter unit (207) can reduce various types of noise occurring in restored blocks. The filter unit (207) can include an edge loop filter, an adaptive loop filter (ALF), a constrained directional enhancement filter (CDEF), a loop restoration filter, etc.

[0098] The filter unit (207) can receive information on whether each filter is applied, information on the strength of the filter, etc. from the image encoding device (100). The filter unit (207) of the image decoding device (200) can receive filter-related information provided from the image encoding device (100) and perform filtering on the corresponding block in the image decoding device (200).

[0099] The filter unit (207) can operate substantially the same as the filter unit (111) of FIG. 1.

[0100] The memory (208) can store the restoration block generated by the addition unit (206). For example, the memory (208) can include a reference picture buffer. The memory (208) can operate substantially the same as the memory (112) of FIG. 1.

[0101]

[0102] FIG. 3 is a diagram schematically showing a video coding system to which the present invention can be applied.

[0103] A video coding system according to one embodiment may include an encoding device (10) and a decoding device (20). The encoding device (10) may transmit encoded video and / or image information or data to the decoding device (20) in the form of a file or streaming through a digital storage medium or a network.

[0104] An encoding device (10) according to one embodiment may include an image generating unit (11), an encoding unit (12), and a transmission unit (13). A decoding device (20) according to one embodiment may include a receiving unit (21), a decoding unit (22), and an image reproducing unit (23). The encoding unit (12) may be referred to as a video / image encoding unit, and the decoding unit (22) may be referred to as a video / image decoding unit. The transmission unit (13) may be included in the encoding unit (12). The receiving unit (21) may be included in the decoding unit (22). The image reproducing unit (23) may include a display unit, and the display unit may be configured as a separate device or an external component.

[0105] The image generation unit (11) can obtain a video / image through a process of capturing, synthesizing, or generating a video / image. The image generation unit (11) can include a video / image capture device and / or a video / image generation device. The video / image capture device can include, for example, one or more cameras, a video / image archive including previously captured video / images, etc. The video / image generation device can include, for example, a computer, a tablet, a smartphone, etc., and can (electronically) generate a video / image. For example, a virtual video / image can be generated through a computer, etc., in which case the video / image capture process can be replaced with a process of generating related data.

[0106] The encoding unit (12) can encode the input video / image. The encoding unit (12) can perform a series of procedures such as prediction, transformation, and quantization for compression and encoding efficiency. The encoding unit (12) can output encoded data (encoded video / image information) in the form of a bitstream. The detailed configuration of the encoding unit (12) can be configured in the same manner as the encoding device (100) of FIG. 1 described above.

[0107] The transmission unit (13) can transmit encoded video / image information or data output in the form of a bitstream to the reception unit (21) of the decoding device (20) via a digital storage medium or a network in the form of a file or streaming. The digital storage medium can include various storage media such as USB, SD, CD, DVD, Blu-ray, HDD, SSD, etc. The transmission unit (13) can include an element for generating a media file through a predetermined file format and can include an element for transmission via a broadcasting / communication network. The reception unit (21) can extract / receive the bitstream from the storage medium or network and transmit it to the decoding unit (22).

[0108] The decoding unit (22) can decode video / image by performing a series of procedures such as inverse quantization, inverse transformation, and prediction corresponding to the operation of the encoding unit (12). The detailed configuration of the decoding unit (22) can be configured identically to the decoding device (200) of FIG. 2 described above.

[0109] The image playback unit (23) can render decrypted video / images. The rendered video / images can be displayed through the display unit.

[0110]

[0111] FIG. 4 is a drawing exemplarily showing a content streaming system to which an embodiment according to the present invention can be applied.

[0112] As illustrated in FIG. 4, a content streaming system to which an embodiment of the present invention is applied may largely include a multimedia input device, a media storage, an encoding server, a streaming server, a web server, and a user device.

[0113] The encoding server compresses content input from multimedia input devices such as smartphones, cameras, CCTVs, etc. into digital data, creates a bitstream, and transmits it to the streaming server. Alternatively, the encoding server compresses content already stored in a media storage into digital data, creates a bitstream, and transmits it to the streaming server.

[0114] As another example, if multimedia input devices such as smartphones, cameras, CCTVs, etc. directly generate bitstreams, the encoding server may be omitted.

[0115] The above bitstream can be generated by a video encoding method and / or a video encoding device to which an embodiment of the present invention is applied, and the streaming server can temporarily or non-temporarily store the bitstream during the process of transmitting or receiving the bitstream.

[0116] The streaming server transmits multimedia data to a user device based on a user request via a web server, and the web server can act as an intermediary to inform the user of available services. When the user device requests a desired service from the web server, the web server transmits the request to the streaming server, and the streaming server can transmit multimedia data to the user device. At this time, the content streaming system may include a separate control server, and in this case, the control server may play a role in controlling commands / responses between each device within the content streaming system.

[0117] The streaming server can receive content from a media repository and / or encoding server. For example, when receiving content from the encoding server, the content can be received in real time. In this case, to provide a smooth streaming service, the streaming server can store the bitstream for a certain period of time.

[0118] Examples of the user devices may include mobile phones, smart phones, laptop computers, digital broadcasting terminals, personal digital assistants (PDAs), portable multimedia players (PMPs), navigation devices, slate PCs, tablet PCs, ultrabooks, wearable devices (e.g., smartwatches, smart glasses, HMDs), digital TVs, desktop computers, digital signage, etc.

[0119] Each server within the above content streaming system can be operated as a distributed server, in which case data received from each server can be processed in a distributed manner.

[0120]

[0121] According to a video encoding method, in order to eliminate spatial information redundancy between a current block and a reference block, only the differential value between the current block and the reference block can be encoded. Then, the encoder can transmit information about the differential value between the encoded coding block and the reference block to the decoder. Here, the encoder can encode the difference between the motion vector prediction (mvp) of the current block and the motion vector of the current block (motion vector difference (mvd)) and transmit the encoded motion vector difference to the decoder.

[0122] In order to represent relative motion in two dimensions, the x-component and y-component of the motion vector difference can be derived, respectively. Then, the values ​​of the x-component and y-component of the motion vector difference can be encoded, respectively. For example, if the motion vector of the current block is (5, 4) and the motion vector prediction is (1, 2), the motion vector difference can be (4, 2). Then, the value 4 of the x-component and the value 2 of the y-component of the motion vector difference can be encoded, respectively.

[0123] Here, as the resolution of the video increases, the number of transmission bits used to code the motion vector difference may increase. Consequently, inefficiency in representing the motion vector difference used in the video encoding method may increase.

[0124] According to the VVC standard, MMVD (merge mode with motion vector difference) is defined to efficiently encode motion vector differences. However, the MMVD method is a mode dependent on the merge mode among inter predictions, and can only encode the difference value of the motion vector induced by the merge mode. In addition, according to the MMVD method, only the motion vector difference expressed on the x-axis or y-axis can be encoded. In other words, the MMVD method can only encode a limited number of motion vector differences.

[0125]

[0126] According to one embodiment of the present disclosure, instead of independently encoding the x-component and the y-component of the motion vector difference, the x-component and the y-component of the motion vector difference can be encoded as a group. Specifically, in order to encode the motion vector difference, at least one area in which the motion vector difference can be distributed on a coordinate system can be defined. Then, information indicating an area including the motion vector difference can be encoded. Then, information indicating a relative position of the motion vector difference within a predetermined area can be further encoded.

[0127]

[0128] FIG. 5 is a diagram illustrating a predetermined area for encoding a motion vector difference according to one embodiment of the present invention.

[0129] Referring to FIG. 5, a predetermined area can be defined on a coordinate system. Specifically, the predetermined area can be defined as -a1 ≤ x ≤ a2 or -a3 ≤ y ≤ a4. In addition, information regarding an area including a motion vector difference can be defined. The information regarding an area including a motion vector difference can include a flag indicating whether a motion vector difference value exists within the predetermined area.

[0130] For example, if the values ​​of a1, a2, a3, and a4 are 1, and the motion vector difference is (1, 0), the motion vector difference exists in the given region. Therefore, the value of the flag can have the first value. On the other hand, if the motion vector difference is (2, 2), the motion vector difference does not exist in the given region. Therefore, the value of the flag can have the second value.

[0131] If the information used to encode the motion vector difference further includes sign-related information, a given region can be defined as 0 ≤ x ≤ a1 or 0 ≤ y ≤ a3.

[0132]

[0133] FIG. 6 is a diagram illustrating a predetermined area for encoding a motion vector difference according to one embodiment of the present invention.

[0134] Referring to FIG. 6, a predetermined area can be defined on a coordinate system. Specifically, the predetermined area can be defined as -a1 ≤ x ≤ a2 and -a3 ≤ y ≤ a4. In addition, information regarding an area including a motion vector difference can be defined. The information regarding an area including a motion vector difference can include a flag indicating whether a motion vector difference value exists within the predetermined area.

[0135] For example, if the values ​​of a1, a2, a3, and a4 are 1, and the motion vector difference is (1, 0), the motion vector difference exists in the given region. Therefore, the value of the flag can have the first value. On the other hand, if the motion vector difference is (2, 2), the motion vector difference does not exist in the given region. Therefore, the value of the flag can have the second value.

[0136] If the information used to encode the motion vector difference further includes sign-related information, a given region can be defined as 0 ≤ x ≤ a1 and 0 ≤ y ≤ a3.

[0137]

[0138] FIG. 7 is a diagram illustrating a predetermined area for encoding a motion vector difference according to one embodiment of the present invention.

[0139] Referring to Fig. 7, a predetermined area can be defined on a coordinate system. Specifically, the predetermined area can be defined as -a1 ≤ x + y ≤ a2. In addition, information regarding an area including a motion vector difference can be defined. The information regarding an area including a motion vector difference can include a flag indicating whether a motion vector difference value exists within the predetermined area.

[0140] For example, if the values ​​of a1 and a2 are 1 and the motion vector difference is (1, 0), the motion vector difference exists in a given region. Therefore, the value of the flag can have the first value. On the other hand, if the motion vector difference is (2, 2), the motion vector difference does not exist in the given region. Therefore, the value of the flag can have the second value.

[0141] If the information used to encode the motion vector difference further includes sign-related information, a given region can be defined as 0 ≤ x + y ≤ a1.

[0142]

[0143] FIG. 8 is a diagram illustrating a predetermined area for encoding a motion vector difference according to one embodiment of the present invention.

[0144] Referring to Fig. 8, a predetermined area can be defined on a coordinate system. Specifically, the predetermined area can be defined as -a1 ≤ xy ≤ a2. In addition, information regarding an area including a motion vector difference can be defined. The information regarding an area including a motion vector difference can include a flag indicating whether a motion vector difference value exists within the predetermined area.

[0145] For example, if the values ​​of a1 and a2 are 1 and the motion vector difference is (1, 0), the motion vector difference exists in a given region. Therefore, the value of the flag can have the first value. On the other hand, if the motion vector difference is (2, 2), the motion vector difference does not exist in the given region. Therefore, the value of the flag can have the second value.

[0146] If the information used to encode the motion vector difference further includes sign-related information, a given region can be defined as 0 ≤ x - y ≤ a1.

[0147] Additionally, a given region can be defined in various ways. In this case, the encoder can encode information indicating how to define the given region and transmit the encoded information to the decoder. Alternatively, the encoder and decoder can derive a method for defining the given region based on the coding parameters of blocks adjacent to the current block.

[0148]

[0149] FIG. 9 is a diagram illustrating a predetermined area for encoding a motion vector difference according to one embodiment of the present invention.

[0150] Referring to Fig. 9, a predetermined area may be defined on a coordinate system. Specifically, the predetermined area may be defined as |x| + |y| ≤ a1. In addition, information regarding an area including a motion vector difference may be defined. The information regarding an area including a motion vector difference may include a flag indicating whether a motion vector difference value exists within the predetermined area.

[0151] For example, if the value of a1 is 1 and the motion vector difference is (1, 0), the motion vector difference exists in the given region. Therefore, the value of the flag can have the first value. On the other hand, if the motion vector difference is (2, 2), the motion vector difference does not exist in the given region. Therefore, the value of the flag can have the second value.

[0152] Alternatively, a given region may be defined as a1 ≤ |x| + |y| ≤ a2. In this case, information regarding a region including a motion vector difference may be defined. The information regarding a region including a motion vector difference may include a flag indicating whether a motion vector difference value exists within the given region.

[0153] Additionally, a given region can be defined in various ways. In this case, the encoder can encode information indicating how to define the given region and transmit the encoded information to the decoder. Alternatively, the encoder and decoder can derive a method for defining the given region based on the coding parameters of blocks adjacent to the current block.

[0154]

[0155] According to one embodiment of the present disclosure, a plurality of points can be defined on a coordinate system, and information indicating points corresponding to motion vector differences can be encoded.

[0156]

[0157] FIG. 10 is a diagram illustrating a plurality of points for encoding a motion vector difference according to one embodiment of the present invention.

[0158] Referring to FIG. 10, multiple points may be defined on a coordinate system. For example, the multiple points may be (0, 0), (0, 1), and (1, 1). In addition, information indicating a point corresponding to a motion vector difference may be defined. The information indicating a point corresponding to a motion vector difference may include an index indicating a point corresponding to a motion vector difference value among the multiple points.

[0159] For example, if the index value is 0, it can indicate the point (0, 0). If the index value is 1, it can indicate the point (0, 1). If the index value is 2, it can indicate the point (1, 0). And, if the index value is 3, it can indicate that it corresponds to a point other than that point. In this case, additional information about the motion vector difference can be transmitted to the decoder.

[0160] Alternatively, the plurality of points may be (0, 0), (1, 0), (-1, 0), (0, 1), (0, -1), (1, 1), (-1, 1), (1, -1), and (-1, -1). The information indicating the point corresponding to the motion vector difference may indicate one of the plurality of points.

[0161] If the information used to encode the motion vector difference includes further sign-related information, multiple points can be defined as (0, 0), (1, 0), (0, 1), (1, 1).

[0162] Additionally, the specified points can be defined in various ways. In this case, the encoder can encode information indicating how to define the specified points and transmit the encoded information to the decoder. Alternatively, the encoder and decoder can derive a method for defining the specified points based on the coding parameters of blocks adjacent to the current block.

[0163]

[0164] According to one embodiment of the present disclosure, instead of encoding the x-component and y-component of a motion vector difference independently, the x-component and y-component of the motion vector difference can be encoded as a group. Specifically, in order to encode the motion vector difference, at least one linear region in which the motion vector difference can be distributed on a coordinate system can be defined. Then, information indicating the linear region including the motion vector difference can be encoded.

[0165]

[0166] FIG. 11 is a diagram illustrating a plurality of linear regions for encoding a motion vector difference according to one embodiment of the present invention.

[0167] Referring to FIG. 11, a plurality of linear regions can be defined on a coordinate system. For example, the plurality of linear regions can be defined as a first linear region where x + y = 0, a second linear region where x + y = a1, and a third linear region where x + y = -a2. For example, a1 and a2 can be 1. In addition, information about a region including a motion vector difference can be defined. The information about a region including a motion vector difference can include an index indicating a linear region including a motion vector difference value among the plurality of regions.

[0168] Here, if the index value is 0, the motion vector difference can be located in the first linear region. If the index value is 1, the motion vector difference can be located in the second linear region. If the index value is 2, the motion vector difference can be located in the third linear region. And, if the index value is 3, the motion vector difference can be located in a region other than the corresponding linear regions. In this case, additional information about the motion vector difference can be transmitted to the decoder.

[0169] Alternatively, the information used to encode the motion vector difference may further include sign-related information. In this case, the plurality of linear regions may be defined as a first linear region where x + y = 0, a second linear region where x + y = a1, and a third linear region where x + y = a2. Here, a1 and a2 may be positive real numbers.

[0170]

[0171] FIG. 12 is a diagram illustrating a plurality of linear regions for encoding a motion vector difference according to one embodiment of the present invention.

[0172] Referring to FIG. 12, a plurality of linear regions can be defined on a coordinate system. For example, the plurality of linear regions can be defined as a first linear region where x - y = 0, a second linear region where x - y = a1, and a third linear region where x - y = -a2. For example, a1 and a2 can be 1. In addition, information about a region including a motion vector difference can be defined. The information about a region including a motion vector difference can include an index indicating a linear region including a motion vector difference value among the plurality of regions.

[0173] Here, if the index value is 0, the motion vector difference can be located in the first linear region. If the index value is 1, the motion vector difference can be located in the second linear region. If the index value is 2, the motion vector difference can be located in the third linear region. And, if the index value is 3, the motion vector difference can be located in a region other than the corresponding linear regions. In this case, additional information about the motion vector difference can be transmitted to the decoder.

[0174] Alternatively, the information used to encode the motion vector difference may further include sign-related information. In this case, the plurality of linear regions may be defined as a first linear region where x - y = 0, a second linear region where x - y = a1, and a third linear region where x - y = a2. Here, a1 and a2 may be positive real numbers.

[0175] Additionally, predetermined linear regions can be defined in various ways. In this case, the encoder can encode information indicating how to define the predetermined linear regions and transmit the encoded information to the decoder. Alternatively, the encoder and decoder can derive a method for defining the predetermined linear regions based on the coding parameters of blocks adjacent to the current block.

[0176]

[0177] Alternatively, predetermined linear regions can be defined as ax + by = c, where a, b, and c can be any real numbers. The number of predetermined linear regions can be three or more. In this case, the index can have an integer value greater than or equal to three.

[0178]

[0179] According to one embodiment of the present disclosure, in order to encode a motion vector difference, a plurality of predetermined regions in which the motion vector difference can be distributed on a coordinate system can be defined. Then, information indicating a predetermined region containing the motion vector difference among the plurality of predetermined regions can be encoded. Then, information indicating the relative position of the motion vector difference in the predetermined region containing the motion vector difference can be further encoded.

[0180]

[0181] FIG. 13 is a diagram illustrating a plurality of areas for encoding a motion vector difference according to one embodiment of the present invention.

[0182] Referring to FIG. 13, a plurality of predetermined regions may be defined on a coordinate system. Specifically, the predetermined regions may include a first region including (0, 0), a second region defined by -a1 ≤ x ≤ a2 or -a3 ≤ y ≤ a4, and a third region defined by -a5 ≤ x ≤ a6 or -a7 ≤ y ≤ a8. In addition, information regarding a region including a motion vector difference may be defined. The information regarding a region including a motion vector difference may include an index indicating a region including a motion vector difference value among the plurality of regions.

[0183] Here, when the index value is 0, the motion vector difference can be located in the first region. When the index value is 1, the motion vector difference can be located in the second region excluding the first region. When the index value is 2, the motion vector difference can be located in the third linear region excluding the first and second regions. And, when the index value is 3, the motion vector difference can be located in a region other than the predetermined regions. In this case, additional information about the motion vector difference can be transmitted to the decoder.

[0184] The information used to encode the motion vector difference may further include sign-related information. In this case, the predetermined regions may include a first region including (0, 0), a second region defined as 0 ≤ x ≤ a1 or 0 ≤ y ≤ a2, and a third region defined as 0 ≤ x ≤ a3 or 0 ≤ y ≤ a4.

[0185]

[0186] FIG. 14 is a diagram illustrating a plurality of areas for encoding a motion vector difference according to one embodiment of the present invention.

[0187] Referring to FIG. 14, a plurality of predetermined regions may be defined on a coordinate system. Specifically, the predetermined regions may include a first region including (0, 0), a second region defined by -a1 ≤ x ≤ a2 and -a3 ≤ y ≤ a4, and a third region defined by -a5 ≤ x ≤ a6 and -a7 ≤ y ≤ a8. In addition, information regarding a region including a motion vector difference may be defined. The information regarding a region including a motion vector difference may include an index indicating a region including a motion vector difference value among the plurality of regions.

[0188] Here, when the index value is 0, the motion vector difference can be located in the first region. When the index value is 1, the motion vector difference can be located in the second region excluding the first region. When the index value is 2, the motion vector difference can be located in the third linear region excluding the first and second regions. And, when the index value is 3, the motion vector difference can be located in a region other than the predetermined regions. In this case, additional information about the motion vector difference can be transmitted to the decoder.

[0189] The information used to encode the motion vector difference may further include sign-related information. In this case, the predetermined regions may include a first region including (0, 0), a second region defined by 0 ≤ x ≤ a1 and 0 ≤ y ≤ a2, and a third region defined by 0 ≤ x ≤ a3 and 0 ≤ y ≤ a4.

[0190]

[0191] FIG. 15 is a diagram illustrating a plurality of areas for encoding a motion vector difference according to one embodiment of the present invention.

[0192] Referring to FIG. 15, a plurality of predetermined regions may be defined on a coordinate system. Specifically, the predetermined regions may include a first region including (0, 0), a second region defined by x + y ≤ a1, and a third region defined by x + y ≤ a2. In addition, information regarding a region including a motion vector difference may be defined. The information regarding a region including a motion vector difference may include an index indicating a region including a motion vector difference value among the plurality of regions.

[0193] Here, when the index value is 0, the motion vector difference can be located in the first region. When the index value is 1, the motion vector difference can be located in the second region excluding the first region. When the index value is 2, the motion vector difference can be located in the third linear region excluding the first and second regions. And, when the index value is 3, the motion vector difference can be located in a region other than the predetermined regions. In this case, additional information about the motion vector difference can be transmitted to the decoder.

[0194] When sign-related information is defined as separate information for defining multiple predetermined areas, the predetermined areas can be defined by taking into account the sign-related information.

[0195] Alternatively, a linear function for defining certain linear regions can be defined as ax + by = c, where a, b, and c can be any real numbers.

[0196]

[0197] FIG. 16 is a diagram illustrating a plurality of areas for encoding a motion vector difference according to one embodiment of the present invention.

[0198] Referring to FIG. 16, a plurality of predetermined areas may be defined on a coordinate system. Specifically, the predetermined areas may include a first area including (0, 0), a second area defined by x - y ≤ a1, and a third area defined by x - y ≤ a2. In addition, information regarding an area including a motion vector difference may be defined. The information regarding an area including a motion vector difference may include an index indicating an area including a motion vector difference value among the plurality of areas.

[0199] Here, when the index value is 0, the motion vector difference can be located in the first region. When the index value is 1, the motion vector difference can be located in the second region excluding the first region. When the index value is 2, the motion vector difference can be located in the third linear region excluding the first and second regions. And, when the index value is 3, the motion vector difference can be located in a region other than the predetermined regions. In this case, additional information about the motion vector difference can be transmitted to the decoder.

[0200] When sign-related information is defined as separate information for defining multiple predetermined areas, the predetermined areas can be defined by taking into account the sign-related information.

[0201] Alternatively, a linear function for defining certain linear regions can be defined as ax + by = c, where a, b, and c can be any real numbers.

[0202]

[0203] FIG. 17 is a diagram illustrating a plurality of areas for encoding a motion vector difference according to one embodiment of the present invention.

[0204] Referring to Fig. 17, a plurality of predetermined areas can be defined on the coordinate system. Here, the plurality of predetermined areas can be defined based on the sum of the absolute values ​​of the components of the motion vector difference.

[0205] Specifically, the predetermined regions may include a first region including (0, 0), a second region defined by |x| + |y| = a1, and a third region defined by |x| + |y| = a2. In addition, information about a region including a motion vector difference may be defined. The information about the region including a motion vector difference may include an index indicating a region including a motion vector difference value among a plurality of regions. Since the plurality of predetermined regions are defined based on the absolute values ​​of components of the motion vector difference, the index may indicate the absolute values ​​of the components of the motion vector difference.

[0206] Here, when the index value is 0, the motion vector difference is located in the first region, and the sum of the absolute values ​​of the x and y components of the motion vector difference may be 0. When the index value is 1, the motion vector difference is located in the second region, and the sum of the absolute values ​​of the x and y components of the motion vector difference may be 1. When the index value is 2, the motion vector difference is located in the third region, and the sum of the absolute values ​​of the x and y components of the motion vector difference may be 2. And, when the index value is 3, the motion vector difference may be located in an region other than the predetermined regions. In this case, additional information about the motion vector difference may be transmitted to the decoder.

[0207] In another embodiment, a plurality of predetermined regions may be defined on the coordinate system. Here, the plurality of predetermined regions may be defined based on the range of the sum of the absolute values ​​of the components of the motion vector difference. For example, when the sample unit of the motion vector difference is a fractional sample, the plurality of predetermined regions may be defined based on the range of the sum of the absolute values ​​of the components of the motion vector difference.

[0208] Referring to FIG. 17, a plurality of predetermined regions may be defined on a coordinate system. Specifically, the predetermined regions may include a first region including (0, 0), a second region defined by |x| + |y| ≤ a1, and a third region defined by |x| + |y| ≤ a2. In addition, information regarding a region including a motion vector difference may be defined. The information regarding a region including a motion vector difference may include an index indicating a region including a motion vector difference value among the plurality of regions.

[0209] Here, when the index value is 0, the motion vector difference can be located in the first region. When the index value is 1, the motion vector difference can be located in the second region excluding the first region. When the index value is 2, the motion vector difference can be located in the third region excluding the first and second regions. And, when the index value is 3, the motion vector difference can be located in a region other than the predetermined regions. In this case, additional information about the motion vector difference can be transmitted to the decoder.

[0210]

[0211] Despite the information about the motion vector difference, if the component (x, y) values ​​of the motion vector difference are not fixed to specific values, additional information for specifying the component (x, y) of the motion vector difference may be transmitted. For example, additional information for specifying the component (x, y) of the motion vector difference may be transmitted together with information about whether the motion vector difference is included in a given region.

[0212] For example, if the motion vector difference is (3,3) and a predetermined region is defined as 2 ≤ x ≤ 4 and 2 ≤ y ≤ 4, the information about the motion vector difference may include information indicating that the motion vector difference is located in the predetermined region. In addition, the information about the motion vector difference may further include information indicating (1, 1), which is a relative position of the motion vector difference from (2, 2), which is a point having a minimum x value and a minimum y value in the predetermined region.

[0213] Here, the x-component and y-component of the relative position of the motion vector difference can be encoded independently. Alternatively, the x-component and y-component of the relative position of the motion vector difference can be encoded using a table defined by combining each component.

[0214] Alternatively, when at least one predetermined region is defined by the operation of the x component and the y component, the information about the motion vector difference may include information indicating that the motion vector difference is located in the predetermined region. In addition, the information about the motion vector difference may further include additional information for specifying at least one of the x component or the y component of the motion vector difference. Here, the additional information may be information for specifying one of the x component or the y component. In addition, the additional information may specify one of the x component or the y component of the motion vector difference in consideration of the relative position of the motion vector difference in the predetermined region.

[0215] For example, at least one predetermined region may be defined as a first region defined by x + y = 0, a second region defined by x + y = 1, and a third region defined by x + y = 2. Here, the region is specified by information indicating a predetermined region where a motion vector difference is located (e.g., x + y = 2), and if the additional information indicates that the x component of the motion vector difference is 2, the motion vector difference may be specified as (2, 0).

[0216] Alternatively, the additional information may be information indicating one of the possible combinations within the given region. Specifically, the additional information may be defined as an index or offset indicating one of the values ​​of the motion vector difference defined over the given region.

[0217] For example, at least one predetermined region may be defined as a first region defined by x + y = 0, a second region defined by x + y = 1, and a third region defined by x + y = 2. Here, the region is specified by information indicating a predetermined region where a motion vector difference is located (e.g., x + y = 2), and the motion vector difference may be specified when the additional information indicates one of values ​​of the motion vector difference on the specified predetermined region (e.g., (0, 2), (1, 1), (2, 0)).

[0218] Alternatively, when at least one predetermined region is defined by an operation of the absolute value of the x component and the absolute value of the y component, the information about the motion vector difference may include information indicating that the motion vector difference is located in the predetermined region. In addition, the information about the motion vector difference may further include additional information for specifying at least one of the x component or the y component of the motion vector difference. According to one embodiment, the additional information may include information indicating the absolute value of the x component or the y component of the motion vector difference. In addition, at least one of information indicating the sign of the x component of the motion vector difference and information indicating the sign of the y component may be included.

[0219] For example, at least one predetermined region may be defined as a first region defined as (0, 0), a second region defined as |x| + |y| = 1, and a third region defined as |x| + |y| = 2. Here, if the region is specified by information indicating the predetermined region where the motion vector difference is located (e.g., |x| + |y| = 2), and the absolute value of the x component (e.g., |x| = 1) and the signs of each of the x component and the y component are specified by additional information (e.g., x ≥ 0, y ≤ 0), the motion vector difference may be specified as (1, -1).

[0220]

[0221] During the inter prediction process of the current block, the Adaptive Motion Vector Resolution (AMVR) method can be applied. AMVR can be a technique for encoding and decoding the motion vector difference of the current block at various resolutions. That is, when AMVR is applied, the resolution of the motion vector of the current block can be determined differently depending on the coding parameters of the current block. Furthermore, scaling can be applied to the motion vector using the determined motion vector resolution. Therefore, motion vector encoding and decoding can be performed accurately and efficiently.

[0222] For example, a motion vector difference can be encoded based on a table defined by an index indicating an area corresponding to the motion vector difference, additional information for specifying a component of the motion vector difference, and information indicating a sample unit which is a resolution of the motion vector difference. Here, the additional information can include information indicating a value, an absolute value, and a sign of the x component and y component of the motion vector difference.

[0223] As explained above, when group coding the x-component and y-component of the motion vector difference, the x-component and y-component of the motion vector difference can be encoded using the resolution of the motion vector determined by the AMVR method. In this case, information indicating whether the motion vector difference is included and information indicating the relative position of the motion vector difference in a given area can be encoded by reflecting the resolution of the motion vector determined by the AMVR method. For example, when the motion vector difference is located on the x + y = 1 area and the resolution of the motion vector is 1 / 2 sample (half-pel), the information about the area indicating the motion vector difference can indicate the x + y = 4 area. Here, the x-component and y-component of the motion vector difference can be expressed as the position of a scaled half-sample unit.

[0224] Alternatively, even if the AMVR method is applied, the x-component and y-component of the motion vector difference can be expressed as positions in units of integer samples. In this case, the decoder can determine the values ​​of the x-component and y-component of the motion vector difference and scale the motion vector difference.

[0225]

[0226] As described above, when defining at least one area in which motion vector differences can be distributed on a coordinate system and encoding information indicating an area including a motion vector difference, the information indicating an area including a motion vector difference can be CABAC encoded. That is, the information indicating an area including a motion vector difference can be binarized, and CABAC can be applied to each bin. In this case, the information indicating an area including a motion vector difference can be encoded by the same context model. Alternatively, the information indicating an area including a motion vector difference can be encoded by a context model determined based on coding parameters such as the size and shape of the current block, motion differential information of the previous block, block mode, and quantization parameter.

[0227]

[0228] And, as explained above, information indicating the relative position of the motion vector difference within a predetermined area can be further encoded. Information indicating the relative position of the motion vector difference within a predetermined area can be CABAC encoded. That is, information indicating the relative position of the motion vector difference within a predetermined area can be binarized, and CABAC can be applied to each bin. In this case, information indicating the relative position of the motion vector difference within a predetermined area can be encoded by the same context model. Alternatively, information indicating the relative position of the motion vector difference within a predetermined area can be encoded by a context model determined based on coding parameters such as the size and shape of the current block, motion difference information of the previous block, block mode, and quantization parameter.

[0229]

[0230] And, as explained above, information indicating the sign of each component of the motion vector difference can be further encoded. Here, the information indicating the sign of each component of the motion vector difference can be CABAC encoded. And, in order to CABAC encode the information indicating the sign of each component of the motion vector difference, context modeling can be performed on information regarding the sign of the motion vector difference.

[0231] Alternatively, information indicating the sign of each component of the motion vector difference may not be signaled. In this case, the decoder can derive the sign of each component of the motion vector difference. Specifically, the decoder can derive the values ​​of the components of the motion vector difference and derive motion vector difference values ​​having different signs. Then, the decoder can apply template matching to reference blocks indicated by different motion vectors using each of the motion vector differences, and derive the sign of the motion vector difference using the motion vector indicating the reference block with the highest similarity among the reference blocks.

[0232] Alternatively, parity encoding can be applied to the motion vector difference based on the presence or absence of 0 in the value of the motion vector difference, and encoding and signaling of information regarding the sign of the motion vector difference can be omitted. In this case, the decoder can derive information regarding the sign of the motion vector difference by applying parity decoding based on the presence or absence of 0 in the value of the motion vector difference.

[0233]

[0234] A method of image decoding using information indicating a region containing motion vector differences may be as described below.

[0235]

[0236] FIG. 18 is a flowchart illustrating an image decoding method using information indicating an area including a motion vector difference according to an embodiment of the present disclosure. The image decoding method of FIG. 16 can be performed by an image decoding device.

[0237] Referring to FIG. 18, the image decoding device can derive a motion vector prediction value of the current block (S1810).

[0238] An image decoding device can obtain information about a motion vector difference of a current block (S1820). Here, the information about the motion vector difference of the current block can include an index indicating an area including at least one combination of an x ​​component value and a y component value of the motion vector difference of the current block.

[0239] Here, a region including at least one combination can be defined by a combination of a range of the x component and a range of the y component of the motion vector difference. And the index can indicate one region among a plurality of regions including different combinations of ranges of the x component and the y component of the motion vector difference.

[0240] Here, information about the motion vector difference of the current block may further include information indicating the difference between the area indicated by the index and the motion vector difference of the current block.

[0241] Here, a region including at least one combination can be defined by a linear function of the x-component and the y-component of the motion vector difference. And, the index can indicate one region among a plurality of regions defined by different linear functions.

[0242] Here, information about the motion vector difference of the current block may further include information indicating the value of one of the x component and the y component of the motion vector difference of the current block.

[0243] Here, information about the motion vector difference of the current block may further include information indicating the sign of the x component of the motion vector difference of the current block and the sign of the y component of the motion vector difference of the current block.

[0244] Meanwhile, a region containing at least one combination can be defined by a linear function of the absolute value of the x component and the absolute value of the y component of the motion vector difference.

[0245] Here, the information about the motion vector difference of the current block may further include information indicating the absolute value of one of the x component and the y component of the motion vector difference of the current block.

[0246] Here, information about the motion vector difference of the current block may further include information indicating the sign of the x component of the motion vector difference of the current block; and information indicating the sign of the y component of the motion vector difference of the current block.

[0247] The video decoding device can derive the motion vector difference of the current block based on information about the motion vector difference (S1830).

[0248] The video decoding device can derive the motion vector of the current block based on the motion vector prediction value and the motion vector difference (S1840).

[0249] Meanwhile, the steps described in FIG. 16 can be performed in the same manner in an image encoding method. Furthermore, a bitstream can be generated by an image encoding method including the steps described in FIG. 16. The bitstream can be stored on a non-transitory computer-readable recording medium and can also be transmitted (or streamed).

[0250]

[0251] While the exemplary methods of this disclosure are presented as a series of operations for clarity of description, this is not intended to limit the order in which the steps are performed, and individual steps may be performed simultaneously or in different orders, if desired. To implement a method according to this disclosure, additional steps may be included in addition to the steps illustrated, some steps may be excluded and the remaining steps may be included, or some steps may be excluded and additional steps may be included.

[0252] The various embodiments of the present disclosure are not intended to list all possible combinations but rather to illustrate representative aspects of the present disclosure, and the matters described in the various embodiments may be applied independently or in combinations of two or more.

[0253] Various embodiments of the present disclosure may be implemented by hardware, firmware, software, or a combination thereof. In the case of hardware implementation, the embodiments may be implemented by one or more Application Specific Integrated Circuits (ASICs), Digital Signal Processors (DSPs), Digital Signal Processing Devices (DSPDs), Programmable Logic Devices (PLDs), Field Programmable Gate Arrays (FPGAs), general processors, controllers, microcontrollers, microprocessors, etc.

[0254] Alternatively, various embodiments of the present disclosure may be implemented in the form of program commands that can be executed by various computer components and recorded on a computer-readable recording medium. Furthermore, a bitstream generated by the encoding method according to the above embodiment may be stored on a non-transitory computer-readable recording medium.

[0255] The computer-readable recording medium may include program commands, data files, data structures, etc., either singly or in combination. The program commands recorded on the computer-readable recording medium may be those specifically designed and configured for the present disclosure or may be known and available to those skilled in the art of computer software.

[0256] As described above, the present disclosure has been described based on specific details, such as specific components, and limited embodiments and drawings. However, the embodiments of the present disclosure are provided merely to facilitate a general understanding of the present disclosure and are not intended to limit the present disclosure to these embodiments. Accordingly, those skilled in the art will appreciate that various modifications and variations can be made based on the description.

[0257] Therefore, the idea of ​​the present invention should not be limited to the embodiments described above, and all things that are modified equally or equivalently to the following claims as well as the claims are considered to fall within the scope of the idea of ​​the present invention.

[0258] The present invention can be used in a device for encoding an image, a device for decoding an image, and a recording medium for storing a bitstream.

Claims

1. In the video decryption method, A step of deriving a motion vector prediction value of the current block; A step of obtaining information about the motion vector difference of the current block; A step of deriving a motion vector difference of the current block based on information about the motion vector difference; and A step of deriving a motion vector of the current block based on the motion vector prediction value and the motion vector difference, Information about the motion vector difference of the current block above, An image decoding method, characterized in that it includes an index indicating an area including at least one combination of values ​​of the x component and values ​​of the y component of the motion vector difference of the current block.

2. In paragraph 1, An area comprising at least one of the above combinations, An image decoding method characterized in that the motion vector difference is defined by a combination of a range of an x-component and a range of a y-component.

3. In paragraph 2, The above index is, An image decoding method characterized in that one region is indicated among a plurality of regions including a combination of different x-component ranges and y-component ranges of motion vector differences.

4. In paragraph 2, Information about the motion vector difference of the current block above, A video decoding method, characterized in that it further includes information indicating the difference between the motion vector difference of the area indicated by the index and the current block.

5. In paragraph 1, An area comprising at least one of the above combinations, An image decoding method characterized in that the motion vector difference is defined by a linear function between the x component and the y component.

6. In paragraph 5, The above index is, An image decoding method characterized by indicating one region among a plurality of regions defined by different linear functions.

7. In paragraph 5, Information about the motion vector difference of the current block above, An image decoding method, characterized in that it further includes information indicating a value of one of the x component and the y component of the motion vector difference of the current block.

8. In paragraph 1, Information about the motion vector difference of the current block above, Information indicating the sign of the x component of the motion vector difference of the current block; and An image decoding method, characterized in that it further includes information indicating the y sign of a component of the motion vector difference of the current block.

9. In paragraph 1, An area comprising at least one of the above combinations, An image decoding method characterized in that the motion vector difference is defined by a linear function of the absolute value of the x component and the absolute value of the y component.

10. In paragraph 9, Information about the motion vector difference of the current block above, An image decoding method, characterized in that it further includes information indicating an absolute value of one of the x component and the y component of the motion vector difference of the current block.

11. In paragraph 9, Information about the motion vector difference of the current block above, Information indicating the sign of the x component of the motion vector difference of the current block; and An image decoding method, characterized in that it further includes information indicating the y sign of a component of the motion vector difference of the current block.

12. In the video encoding method, A step of deriving a motion vector prediction value of the current block; A step of obtaining information about the motion vector difference of the current block; A step of deriving a motion vector difference of the current block based on information about the motion vector difference; and A step of deriving a motion vector of the current block based on the motion vector prediction value and the motion vector difference, Information about the motion vector difference of the current block above, A video encoding method, characterized in that it includes an index indicating an area including at least one combination of values ​​of the x component and values ​​of the y component of the motion vector difference of the current block.

13. In a non-transitory computer-readable recording medium storing a bitstream generated by an image encoding method, The above image encoding method is, A step of deriving a motion vector prediction value of the current block; A step of obtaining information about the motion vector difference of the current block; A step of deriving a motion vector difference of the current block based on information about the motion vector difference; and A step of deriving a motion vector of the current block based on the motion vector prediction value and the motion vector difference, Information about the motion vector difference of the current block above, A non-transitory computer-readable recording medium, characterized in that it includes an index indicating an area including at least one combination of values ​​of the x component and values ​​of the y component of the motion vector difference of the current block.

14. In a method for transmitting a bitstream generated by a video encoding method, The above transmission method includes a step of transmitting the bitstream, The above image encoding method is, A step of deriving a motion vector prediction value of the current block; A step of obtaining information about the motion vector difference of the current block; A step of deriving a motion vector difference of the current block based on information about the motion vector difference; and A step of deriving a motion vector of the current block based on the motion vector prediction value and the motion vector difference, Information about the motion vector difference of the current block above, A transmission method characterized in that it includes an index indicating an area including at least one combination of values ​​of the x component and values ​​of the y component of the motion vector difference of the current block.

Images