Fast intra mode decision algorithm based on refinement in HEVC

Abstract

High Efficiency Video Coding (HEVC) is the next generation video compression standard providing significant coding performance. It adopts 35 intra prediction modes with larger CU size to improve the intra encoding efficiency, so that cause a high computational complexity. In this paper, two fast intra-prediction algorithms are proposed to reduce the number of candidate modes for rate-distortion (RD) optimization. We obtain an optimal adjacent modes (OAM) list consisting of dominant directions through the analysis of costs of several general direction modes. Furthermore, we improve the most probable mode (MPM) algorithm to make full use of the spatial correlation between neighbour prediction blocks instead of simply merging the prediction modes of neighbour prediction blocks into the candidate list. Experimental results show that the proposed algorithms can reduce about 27.3% of the encoding time compared to the HEVC test model 14.0, while the decrease of coding quality is negligible.

A fast HEVC intra-coding algorithm based on texture homogeneity and spatio-temporal correlation

“…Therefore, the proposed fast coding mode decision algorithm provides the best performance in terms of encoding time reduction. Table 5 provides the simulation results of the proposed hybrid algorithm when compared with the original HM implementation and three state-of-the-art fast HEVC intra-coding algorithms, namely, those proposed by Gao [9], Shang [20] and Zhang [21]. It can be seen that the time reduction achieved by our algorithm is 55.24% on average.…”

“…These are categorised into mainly three types: fast coding depth decision [2][3][4][5][6][7][8], fast prediction mode decision [9][10][11][12][13][14][15][16][17][18][19] and hybrid fast scheme [20][21][22][23][24][25][26]. Some typical algorithms in each category are described as follows:…”

“…• Fast prediction mode decision: The fast mode decision proposed by Gao [9] employed the spatial correlation between neighbouring blocks. In [10], a computational complexity reduction scheme for intra-coding was proposed by Jamali, where the edge property, spatial correlation between neighbouring PUs, and the classification of SATD costs were used.…”

Review of Fast Mode Decision Algorithms for Intra Prediction in High Efficiency Video Coding Standard

“…L. Gao et. al.in [20] proposed two fast intra prediction algorithms to reduce the number of candidate modes for rate distortion optimization by obtaining an optimal adjacent modes (OAM) list consisting of dominant directions through the analysis of costs of several general direction modes.Further the most probable mode algorithm is improved to make full use of the spatial correlation between neighbor prediction blocks instead of merging the prediction modes of neighbor prediction blocks into the candidate list. The proposed approach reduce about 27.3% of the encoding time with decrease of coding quality.…”

Coding unit splitting early termination for fast HEVC intra coding based on global and directional gradients

“…Fast HEVC intra coding is realized either by fast mode decision, i.e., a decrease in the number of modes to be checked by the high-complexity rate distortion optimization (RDO) process [4]- [7], or by CU splitting early termination, i.e., RDO is performed only for some selected CU levels. In [8], the depth information of the neighbouring CUs is exploited in order to take advantage of the spatial correlation in a frame.…”