The application relates to an encoding and decoding method and apparatus, an encoding-side device, and a decoding-side device. The method includes: if characteristic information of a current block meets a specific condition, determining a first reference block corresponding to the current block according to a first original motion vector of the current block, and determining a second reference block corresponding to the current block according to a second original motion vector of the current block; adjusting the first and second original motion vectors according to a first pixel value of the first reference block and a second pixel value of the second reference block to obtain a first target motion vector corresponding to the first original motion vector and a second target motion vector corresponding to the second original motion vector; encoding or decoding the current block according to the first and second target motion vectors.