Bidirectional predictive encoding method, decoding method and apparatus

The present invention provides a coding method based on bidirectional prediction, the decoding method and apparatus. The decoding method comprising: an enhancement layer of the current image according to the at least one enhancement layer reference image and a residual image at least a base layer image corresponding to the reference image generating at least one enhancement layer, and the at least one residual image as at least one first reference a first reference image is added to the list of the current image of the image enhancement layer; generating an image according to the base layer image corresponding to the second reference image of the current enhancement layer, and the addition of the second reference image to the current image of the second enhancement layer reference image list; a list based on a first reference picture and a second reference picture list, the bidirectional prediction block of the image enhancement layer of the current image is encoded. The present invention, each image block using the differential mode flag is set to achieve no need to lower the cost.