Adaptive intra mode skipping algorithm for inter frame coding of H.264/AVC

Abstract

Compared to contemporary video coding standards, the H.264 standard achieves higher compression efficiency at the expense of high computational complexity at the encoder to carry out rate distortion optimization (RDO). In this paper, we investigated the encoding speed improvement technology of H.264 and focus on RDO to select the encode mode for fast coding of H.264. Based on the analysis of motion activity information of the macroblock to be coded in inter frame, we proposed a methodology to simplify the computation of encoder while maintaining the coding efficiency. At first, we established the relationships between INTRA mode and motion activity in inter frame. Then the INTRA mode skipping algorithm (IMSA) is proposed and applied to RDO procedure. If the motion activity of a macroblock is small enough, then IMSA adaptively skips the whole INTRA mode decision process because the encoder benefits little from such type of macroblocks. Simulation results demonstrate its valuable efficiency of considerably reducing 30%~60% encoding complexity while incurring little even no loss in quality and increase in bit rate. Additionally, it is easier than other published fast mode decision algorithms and more efficient when working together with them.