Skip Mode Coding for Nonsquare Prediction Blocks

Abstract

In the inter-frame coding, the SKIP mode with the application of few signaling bits is a highly-efficient prediction method. Specifically, it can skip over the encoding process of motion vectors, residuals and other syntax elements. Moreover, the motion information of adjacent blocks is adopted to predict the motion parameters of the skipped blocks according to the spatial correlations. In the state-of-art designs, the SKIP mode is generally used for a square prediction block, thus leaving broad space for further investigations. Since the nonsquare prediction mode has been proved to be an effective tool, this paper proposes to employ the SKIP mode for the nonsquare prediction mode. We believe that the nonsquare SKIP mode can further save the signaling bits, because all-zero residuals will occur in the nonsquare blocks. Considering that the nonsquare prediction blocks probably contain directional features, a nonsquare transform is proposed hereafter. The test model of the latest High Efficiency Video Coding (HEVC) standard is applied in this research to examine the performance of the proposed method, and the test results show that the coding performance has been improved.