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

An apparatus for decoding a video signal based on inter prediction, comprising:

• a memory configured to store the video signal;
• and
• a processor coupled with the memory,
• wherein the processor is configured to:
• derive a motion vector predictor based on motion information of a neighboring block of a current block;
• derive a motion vector difference of the current block based on layer information and index information, wherein the layer information represents a current layer, which the motion vector difference used for the inter prediction of the current block belongs to, in a predefined layer structure in which at least one combination of horizontal and vertical components of the motion vector difference is divided into a plurality of layers, and the index information represents a specific combination of vertical and horizontal components of the motion vector difference within the current layer;
• derive a motion vector of the current block based on the motion vector predictor and the motion vector difference;
• generate a prediction block of the current block based on the motion vector of the current block;
• and
• generate a reconstructed block of the current block based on the prediction block and a residual block of the current block,
• wherein the layer information includes at least one syntax element indicating a layer group to which the current layer belongs,
• wherein the index information is binarized based on a truncated binarization scheme,
• wherein deriving the motion vector difference further comprises:
• obtaining a first syntax element representing whether an identification (ID) of the current layer is greater than 0,
• obtaining a second syntax element indicating whether the current layer belongs to a first layer group when the ID of the current layer is greater than 0,
• obtaining a third syntax element indicating whether the ID of the current layer is 1 or 2 when the current layer belongs to the first layer group, and
• obtain ID information indicating the ID of the current layer when the ID of the current layer is greater than 0, and
• wherein the ID information is binarized based on an exponential Golomb code with order 1.