1. A method of a decoding device to decode a current block in a current picture, comprising: obtaining, by the decoding device, a motion vector of a first neighboring block of the current block, wherein the first neighboring block is in the current picture; interpolating, by the decoding device, the motion vector of the first neighboring block in the current picture based on a distance between a reference picture of the first neighboring block in the current picture and the current picture and a distance between a reference picture of the current block in the current picture and the current picture to generate a first adjacent motion vector for predicting a motion vector of the current block; obtaining, by the decoding device, a motion vector of a second neighboring block of the current block, wherein the second neighboring block is in the current picture and the second neighboring block is different from the first neighboring block; interpolating, by the decoding device, the motion vector of the second neighboring block in the current picture based on a distance between a reference picture of the second neighboring block in the current picture and the current picture and a distance between a reference picture of the current block in the current picture and the current picture to generate a second adjacent motion vector for predicting the motion vector of the current block; predicting, by the decoding device, the motion vector of the current block based on the first adjacent motion vector and the second adjacent motion vector to generate a predicted motion vector of the current block; performing, by the decoding device, a motion compensating by using the predicted motion vector of the current block to generate a motion compensated block of the current block; and adding, by the decoding device, a residual block of the current block and the motion compensated block of the current block to reconstruct the current block.