A fast intra optimization algorithm for HEVC

High Efficiency Video Coding (HEVC) has drastically improved the coding efficiency, and can provide more than 23% bit rate reduction compared to its predecessor H264/AVC for all intra (AI) configuration. However, the improvement on coding efficiency is obtained at the expense of much more intensive computation complexity. In this paper, a fast intra optimization scheme is proposed. Firstly, a shrinkage scheme for the number of mode prediction is proposed based on gradient variance. Then a novel estimation model for rate distortion cost is provided based on Hadamard transform and quantization to better determine the mode prediction for RQT. Experimental results demonstrate that, compared with the original HEVC reference encoder implementation in AI configuration, the proposed algorithms can achieve more than 26% coding complexity reduction on average with ignorable coding performance degradation.