A Fast Inter Prediction Algorithm Based on Rate-Distortion Cost in HEVC

As one of the most important video compression technologies, inter prediction coding is highly efficient in reducing the temporal redundancy of video sequence. However, complicated inter prediction for the latest High Efficiency Video Coding standard (HEVC) brings high computational complexity and seriously restricts the encoding speed. In this paper, a fast inter prediction algorithm based on Rate-Distortion (RD) cost is proposed to improve inter prediction of HEVC. First, the splitting of Largest Coding Unit (LCU) is determined according to the RD costs with best Coding Unit (CU) size being 64x64 in the reference picture. Then, for other CUs in lower depths, the comparable RD costs are selected from encoded CUs in the same depth at the same Coding Tree Unit (CTU) based on the local homogeneity in spatial domain. By comparing the RD cost of current CU with its corresponding RD threshold, the splitting is terminated in advance. In this way, the proposed fast inter prediction algorithm can avoid the traversal of all CUs in the coding tree structure and improve the encoding speed. Experimental results show that the algorithm can save about 30% encoding time on the basis of ensuring visual quality and compression ratio of videos. Therefore, the computational complexity can be reduced greatly.