An encoding and decoding method, apparatus, and device is disclosed. The method comprises: if characteristic information of a current block meets a specific condition, performing the following steps to acquire a target prediction value of the current block or a sub-block of the current block: determining a first original prediction value based on first unidirectional motion information of the current block, and determining a second original prediction value based on second unidirectional motion information of the current block; determining a horizontal velocity based on the first original prediction value and the second original prediction value; determining a vertical velocity based on the first original prediction value and the second original prediction value; acquiring a prediction compensation value based on the horizontal velocity and the vertical velocity; and acquiring the target prediction value based on the first original prediction value, the second original prediction value and the prediction compensation value.