Method and device for processing video signal on basis of inter prediction

A method for encoding a video signal, the method comprising:

• determining whether a merge mode is applied to a current block among a plurality of inter prediction modes, wherein the plurality of inter prediction modes include the merge mode and a Motion Vector Prediction (MVP) mode;
• configuring, based on the merge mode being applied to the current block, a merge list based on a neighboring block of the current block;
• adding a History based Motion Vector Predictor (HMVP) candidate included in a HMVP candidate list to the merge list until a number of a merge candidate included in the merge list is equal to a value being 1 subtracted from a maximum number of merge candidates, wherein the HMVP candidate represents motion information of block coded prior to the current block;
• generating a merge index indicating a merge candidate used for an inter prediction of the current block within the merge list;
• generating prediction samples of the current block based on motion information of the merge candidate indicated by the merge index;
• obtaining residual samples of the current block based on the prediction samples;
• performing a transform on the residual samples to obtain transform coefficients;
• and
• performing a quantization and an entropy-encoding for the transform coefficients,
• wherein the adding the HMVP candidate to the merge list comprises checking of whether a first number of the HMVP candidate within the HMVP candidate list has the same motion information as the merge candidate included in the merge list,
• wherein the first number of the HMVP candidate is added to the merge list based on that it has motion information different with a predefined spatial merge candidate, which is part of the spatial merge candidates included in the merge list,
• wherein the predefined spatial merge candidate includes at least one of a left neighboring block or an upper neighboring block of the current block, and
• wherein the number of the predefined spatial merge candidates is less than the number of the spatial merge candidates included in the merge list.

A method for transmitting video information generated by performing a video signal encoding method, the video signal encoding method comprising:

• determining whether a merge mode is applied to a current block among a plurality of inter prediction modes, wherein the plurality of inter prediction modes include the merge mode and a Motion Vector Prediction (MVP) mode;
• configuring, based on the merge mode being applied to the current block, a merge list based on a neighboring block of the current block;
• adding a History based Motion Vector Predictor (HMVP) candidate included in a HMVP candidate list to the merge list until a number of a merge candidate included in the merge list is equal to a value being 1 subtracted from a maximum number of merge candidates, wherein the HMVP candidate represents motion information of block coded prior to the current block;
• generating a merge index indicating a merge candidate used for an inter prediction of the current block within the merge list;
• generating prediction samples of the current block based on motion information of the merge candidate indicated by the merge index;
• wherein the adding the HMVP candidate to the merge list comprises checking of whether a first number of the HMVP candidate within the HMVP candidate list has the same motion information as the merge candidate included in the merge list,
• wherein the first number of the HMVP candidate is added to the merge list based on that it has motion information different with a predefined spatial merge candidate, which is part of the spatial merge candidates included in the merge list,
• wherein the predefined spatial merge candidate includes at least one of a left neighboring block or an upper neighboring block of the current block, and
• wherein the number of the predefined spatial merge candidates is less than the number of the spatial merge candidates included in the merge list.