Overlapped Block Motion Compensation

Definition

The overlapped block motion compensation (OBMC) [1] aims at reducing the blocking effects by performing a weighted average of overlapped block segments during motion prediction.

In normal motion compensation, the current block is composed of (1) the predicted block from the previous frame (referenced by the motion vectors), and (2) the residual data transmitted in the bit stream for the current block. In OBMC, the prediction is a weighted sum of three predictions.

Let (m, n) be the column and row indices of an 8 × 8 pixel block in a frame; (i, j) be the column and row indices of a pixel within an 8 × 8 block; and (x, y) be the column and row indices of a pixel within the entire frame so that (x, y) = (m × 8 + i, n × 8 + j). Then the weighted prediction for the current block is given by [2]:

$$\eqalign{{\rm P}({\rm x},{\rm y}) = & ({\rm q}({\rm x},{\rm y}){\rm H}^0 ({\rm i},{\rm j}) + {\rm r}({\rm x},{\rm y}){\rm H}^1 ({\rm i},{\rm j}) \cr & + {\rm s}({\rm x},{\rm y}){\rm...