Video signal encoding/decoding method, and device therefor

1 . A method of decoding a video comprising:

determining a partitioning type of a coding block;

deriving a merge candidate list which includes a plurality of merge candidates;

determining a first merge candidate among the plurality of merge candidates based on first index information;

determining a second merge candidate among the plurality of merge candidates based on second index information;

obtaining a first inter-prediction block based on first motion information derived from the first merge candidate;

obtaining a second inter-prediction block based on second motion information derived from the second merge candidate;

obtaining a prediction block of the coding block based on a weighted sum of the first inter-prediction block and the second inter-prediction block; and

reconstructing the coding block by summing the prediction block and a residual block,

wherein one among the plurality of merge candidates whose an index is equal to the first index information is determined as the first merge candidate,

wherein the second merge candidate is determined by comparing the second index information with the first index information,

wherein when the second index information is less than the first index information, one among the plurality of merge candidates whose an index is equal to the second index information is determined as the second merge candidate,

wherein when the second index information is equal to or greater than the first index information, one among the plurality of merge candidates whose an index is equal to a value adding 1 to the second index information is determined as the second merge candidate, and

wherein when the number of merge candidates is less than a predefined number, the second index information is not signaled via a bitstream.

2 . The method of claim 1 ,

wherein the partitioning type is determined among a plurality of partitioning type candidates, and

wherein the plurality of partitioning type candidates comprises a vertical partitioning type candidate which represents that the coding block is divided into 2 partitions by a vertical line, and a horizontal partitioning type candidate which represents that the coding block is divided into 2 partitions by a horizontal line.

3 . The method of claim 1 ,

wherein when the first index information is an even-number, one of L0 motion information or L1 motion information of the first merge candidate is determined as the first motion information, and

wherein when the first index information is an odd-number, the other of the L0 motion information or the L1 motion information of the first merge candidate is determined as the first motion information.

4 . The method of claim 1 ,

wherein a prediction sample in the prediction block is obtained by applying a first weight to a first inter-prediction sample in the first inter-prediction block and applying a second weight to a second inter-prediction sample in the second inter-prediction block, and

wherein the first weight has a greater value when the prediction sample is included in a first partition of the coding block than when the prediction sample is included in a second partition of the coding block.

5 . A video encoding method comprising:

determining a partitioning type of a coding block;

deriving a merge candidate list which includes a plurality of merge candidates;

determining a first merge candidate among the plurality of merge candidates;

determining a second merge candidate among the plurality of merge candidates;

obtaining a first inter-prediction block based on first motion information derived from the first merge candidate;

obtaining a second inter-prediction block based on second motion information derived from the second merge candidate;

obtaining a prediction block of the coding block based on a weighted sum of the first inter-prediction block and the second inter-prediction block; and

obtaining a residual block by subtracting the prediction block from an original block,

wherein first index information for specifying the first merge candidate and second index information for specifying the second merge candidate are encoded,

wherein a value of the first index information is set to be the same as an index of the first merge candidate (hereinafter, “first index”),

wherein a value of the second index information is set by comparing the first index with an index of the second merge candidate (hereinafter, “second index”),

wherein when the second index is less than the first index, the value of the second index information is set to be the same as the second index,

wherein when the second index is equal to or greater than the first index, the value of the second index information is set by subtracting 1 to the second index, and

wherein when the number of merge candidates is less than a predefined number, the second index information is not encoded into a bitstream.