Low-complexity inverse integer transform in H.264/AVC

This work develops an efficiently low-complexity method to compute a 2-dimensional inverse integer transform in H.264/AVC. First, the end-of-block points in 4 × 4 and 8 × 8 blocks are computed and then used to select one of 7 and 15 operation modes for each block, respectively. Second, the computation order of row-after-column and column-after-row used for 1-dimensional inverse integer transforms is adequately chosen to reduce computational complexity. Finally, simplified 1-dimensional inverse integer transforms are employed to accomplish a 2-dimensional inverse integer transform. The simulation results demonstrate that the proposed method can effectively minimize computational complexity of 2-dimensional inverse integer transforms in video streams of H.264/AVC. Particularly, as the smaller is the end-of-block point, the lower is the computational complexity. Therefore, the proposed method can be widely used at various H.264/AVC decoders to reach low-complexity computation.