Methods for efficient implementation of skip/direct modes in digital video compression algorithms

Abstract

The approach of the present invention is to take advantage of similarity in implementation between SKIP and DIRECT modes and one other inter-picture prediction modes, namely, the 16×16 partition mode. The SKIP/DIRECT modes are classified into two groups, one involving inter-picture prediction in one temporal direction in which prediction is chosen from either past or future recon pictures, and the other involving prediction in two temporal directions in which prediction is constructed as a superposition of both past and future recon pictures. The first group requires interpolation for only one direction, whereas the latter requires interpolation for both directions, thus requiring roughly twice as much data processing power than the first group. The 16×16 partition mode also allows both prediction schemes, either past or future, or a superposition of past and future. The SKIP/DIRECT and 16×16 partition modes all apply the same motion vector on the entire block unit. Methods of the present invention consider the SKIP/DIRECT modes if and only if the final prediction information of the 16×16 partition mode, including motion vector, reference picture index, and prediction direction, is the same as that of the respective SKIP and/or DIRECT modes. The point here is that the same motion prediction, reference picture index and prediction direction are used for the 16×16 partition mode and the SKIP/DIRECT modes, and therefore, the same interpolation scheme can be used for both SKIP/DIRECT and 16×16 partition modes, thus saving computational cost as well as implementation cost.