A video image encoding device includes: an image encoding unit that performs predictive encoding by obtaining a difference between a divided image included in a frame as a target of predictive encoding and a prediction image; local decode generation unit that decodes an encoding result of the divided image by the image encoding unit to generate a reference image; a first buffer that stores pixel data generated by the local decode generation unit; a compression unit that refers to the first buffer to compress the reference image and generates compressed data; an allowable data amount setting unit that presets an allowable data amount to be stored in the memory for each predetermined area of the frame as the target of the predictive encoding; and a reference image storage determination unit that determines whether the compressed data is store in the memory based on the allowable data amount, and stores the compressed data in the memory based on a determination result of storing the compressed data in the memory.

A method for video decoding includes determining, based on prediction information, whether the current block uses a flexible partition type. Reconstructed samples of the reference block are stored in a cache memory, which stores reconstructed samples of coding regions of a first size comprising a coding tree unit (CTU) of the current block and reconstructed samples of at least one coding region of the first size comprising a CTU adjacent to the CTU of the current block. The cache memory stores either (i) only reconstructed samples of the coding regions of the CTU of the current block or (ii) reconstructed samples of coding regions of a second size of the CTU of the current block and reconstructed samples of at least one coding region of the second size of the CTU adjacent to the CTU of the current block.

Decoding a current block of a current frame includes obtaining motion trajectories between the current frame and at least one previously coded frame by projecting motion vectors from the at least one previously coded frame onto the current frame. A motion field is obtained between the current frame and a reference frame used for coding the current frame. The motion field is obtained by extending the motion trajectories from the current frame towards the reference frame. A motion vector for the current block is identified based on the motion field. A prediction block is obtained for the current block using a reference block of the reference frame identified using the motion vector.

Decoding a current block of a current frame includes obtaining motion trajectories between the current frame and at least one previously coded frame by projecting motion vectors from the at least one previously coded frame onto the current frame. A motion field is obtained between the current frame and a reference frame used for coding the current frame. The motion field is obtained by extending the motion trajectories from the current frame towards the reference frame. A motion vector for the current block is identified based on the motion field. A prediction block is obtained for the current block using a reference block of the reference frame identified using the motion vector.

The disclosure discloses a method for processing a video signal and an apparatus therefor. Specifically, the method of processing a video signal based on an inter prediction, comprising: configuring a merge list based on a neighboring block of a current block; adding a history based merge candidate included in a history based merge candidate list to the merge list when a number of a merge candidate included in the merge list is smaller than a first predetermined number; obtaining a merge index indicating a merge candidate used for an inter prediction of the current block within the merge list; and generating a prediction block of the current block based on motion information of a merge candidate indicated by the merge index, wherein a step of adding the history based merge candidate to the merge list comprises checking whether a second predetermined number of the history based merge candidate within the history based merge candidate list has the same motion information as the merge candidate included in the merge list.

Disclosed are methods and apparatuses for decoding an image. A method includes receiving a bitstream obtained by encoding the image; dividing a first coding block into a plurality of second coding blocks; generating a prediction block of a second coding block based on syntax information obtained from the bitstream; and reconstructing the second coding block based on the prediction block and a residual block of the second coding block, the residual block being obtained by performing a dequantization and an inverse-transform on quantized transform coefficients from the bitstream. The first coding block has a recursive division structure. The first coding block is divided based on at least one of a quad tree division, a binary tree division or a triple tree division.

A method of deriving prediction sample values for decoding video data by a device is provided. A reference wraparound offset syntax specifying an offset used for computing a horizontal wrap-around position is decoded. A luma location is derived based on a product of a value of the reference wraparound offset syntax and a minimum coding block size. An offset variable is set equal to a value obtained by dividing the product of the value of the reference wraparound offset syntax and the minimum coding block size by a width value, and the width value is specified based on a chroma format. A chroma location is derived by using the offset variable. A predicted luma sample value is derived by using the luma location.

Disclosed is a method of decoding an image and a method of encoding an image. The method of decoding an image includes: obtaining motion-constrained tile set information; determining, on the basis of the motion-constrained tile set information, a first boundary region of a collocated tile set within a reference picture, which corresponds to a motion-constrained tile set; padding a second boundary region corresponding to the first boundary region; and performing inter prediction on the motion-constrained tile set by using a collocated tile set that includes the padded second boundary region.

Disclosed is a method of decoding an image and a method of encoding an image. The method of decoding an image includes: obtaining motion-constrained tile set information; determining, on the basis of the motion-constrained tile set information, a first boundary region of a collocated tile set within a reference picture, which corresponds to a motion-constrained tile set; padding a second boundary region corresponding to the first boundary region; and performing inter prediction on the motion-constrained tile set by using a collocated tile set that includes the padded second boundary region.

A coding tool is provided to improve the compression performance of inter prediction and is used at the encoder/decoder side to adjust the correction of a motion vector based on a high level syntax. In addition, a method is provided for simply performing an integer sample search step of searching for an integer offset and a fractional sample refinement step of searching for a sub-pixel offset in relation to motion vector refinement among coding tools.