Method and apparatus for processing video signal on basis of history-based motion vector prediction

An apparatus of processing video signals based on inter prediction, comprising:

• a memory configured to storing the video signals;
• and
• a processor combined to the memory,
• wherein the processor is configured for:
• configuring a merge candidate list based on a neighboring block to a current block;
• adding a history based merge candidate of the current block to the merge candidate list based on that a number of merge candidates included in the merge candidate list is smaller than a first predetermined number;
• adding a zero motion vector to the merge candidate list based on that the number of merge candidates included in the merge candidate list is smaller than a second predetermined number;
• obtaining a merge index indicating a merge candidate used for inter prediction of the current block in the merge candidate list;
• generating a prediction sample of the current block based on motion information of the merge candidate indicated by the merge index;
• and
• updating a history based merge candidate list based on the motion information,
• wherein the history based merge candidate is added to the merge candidate list based on that the history based merge candidate includes motion information which is not identical to motion information of a predefined merge candidate among merge candidates included in the merge candidate list.