Method and device for decoding video data, and readable storage medium

The invention relates to a method and equipment for decoding video data and a readable storage medium. The method comprises: obtaining a horizontal component and a vertical component of a CPMV for a current block of video data to be coded using an affine mode; determining whether a memory bandwidth required to access a sample of a plurality of reference blocks derived based on a difference between the components of the CPMV satisfies a bandwidth threshold; selectively modifying a motion compensation method for predicting a sample of a current block of video data based on whether the determined memory bandwidth satisfies a bandwidth threshold, wherein the selective modification of the motion compensation method includes grouping together a plurality of sub-blocks of the current block in response to determining that the memory bandwidth does not satisfy the bandwidth threshold; and predicting a sample of a current block of the video data from the samples of the plurality of reference blocks using a selectively