Selective intra-prediction skip algorithm for inter-frame coding in H.264/AVC

Inter-frame coding using inter- and intra-predictions plays an important role in achieving high compression efficiency in H.264/AVC. However, most intra-predictions are unnecessary, since the intra-coding mode occupies less than 5% of the overall coding in inter-frame coding. In this paper, we propose an intra mode skip algorithm for inter-frame coding in H.264/AVC as a means of obtaining fast intra mode decision. The algorithm uses the joint entropy (JE) and mutual information (MI) to extract the temporal correlations between the current block and the reconstructed block based on 8 × 8 motion estimation. All or part of the intra-prediction search is omitted by using JE and MI. Experimental results show that the proposed algorithm is capable of reducing the overall coding time by 15-37% and the overall intra-prediction time by 32-78% compared to full search of the reference software, with negligible loss of quality.