A Fast QTMT Partition Decision Strategy for VVC Intra Prediction

Abstract

Different from the traditional quaternary tree (QT) structure utilized in the previous generation video coding standard H.265/HEVC, a brand new partition structure named quadtree with nested multi-type tree (QTMT) is applied in the latest codec H.266/VVC. The introduction of QTMT brings in superior encoding performance at the cost of great time-consuming. Therefore, a fast intra partition algorithm based on variance and Sobel operator is proposed in this paper. The proposed method settles the novel asymmetrical partition issue in VVC by well balancing the reduction of computational complexity and the loss of encoding quality. To be more concrete, we first terminate further splitting of a coding unit (CU) when the texture of it is judged as smooth. Then, we use Sobel operator to extract gradient features to decide whether to split this CU by QT, thus terminating further MT partitions. Finally, a completely novel method to choose only one partition from five QTMT partitions is applied. Obviously, homogeneous area tends to use a larger CU as a whole to do prediction while CUs with complicated texture are prone to be divided into small sub-CUs and these sub-CUs usually have different textures from each other. We calculate the variance of variance of each sub-CU to decide which partition will distinguish the sub-textures best. Our method is embedded into the latest VVC official reference software VTM-7.0. Comparing to anchor VTM-7.0, our method saves the encoding time by 49.27% on average at the cost of only 1.63% BDBR increase. As a traditional scheme based on variance and gradient to decrease the computational complexity in VVC intra coding, our method outperforms other relative existing state-of-the-art methods, including traditional machine learning and convolution neural network methods. INDEX TERMS Asymmetric block size, fast partition decision, intra prediction, quadtree with multi-type tree, versatile video coding YIBO FAN received the B.E. degree in electronics and engineering from

Fast CU Partition Decision Based on Texture for H.266/VVC

“…Table 4 shows the performance results of the proposed fast algorithm in this paper compared with other fast algorithms. In order to evaluate the performance of the proposed algorithm, we have compared with three fast CU partition algorithms, namely, CTTD [36], FCPD [7], and FPDS [8]. Relative to the anchor method, as can be seen from the table, FCPD has achieved the best encoding quality, the average BDBR of FCPD increased by 0.70%, but the ATS is the smallest compared to other methods, only 34.20%.…”

“…e authors of [8][9][10][11][12][13][14][15][16][17][18][19][20][21] judge texture features by variance or gradient to make skip or early termination. In [8], a gradient method based on texture complexity and gradient-based preprocessing steps are proposed to reduce the number of candidate modes and make early decisions for CU splitting. A fast mode decision algorithm based on gradient is proposed in [9], which calculates the gradient direction and eliminates unnecessary modes based on histogram distribution to reduce the candidate modes before performing the Rough Mode Decision (RMD).…”

Fast CU Partition Decision Algorithm for AVS3 Intra Coding

“…Numerous fast algorithms have been proposed to reduce the coding complexity of VVC. In [14], variance and gradient were utilized to distinguish the large smooth area and complex texture region, and fast partition decision could conduct directly according to these messages. Tang et al [15] used edge features extracted by canny edge detector to skip vertical or horizontal split mode to carry out early termination.…”

“…In the digital image processing field, gradient is an excellent indicator to express the feature of image texture. Reference [10], [14] and [15] have shown that gradient is an effective reference in terminating the partition of homogenous CUs and choosing QT split mode directly to deal with CUs with complex texture. Vertical or horizontal split mode can be skipped if the gradient in the other direction is more outstanding.…”

State-Of-The-Art In Video Processing: Compression, Optimization And Retrieval

“…PU modes and CU combinations [4] are iteratively examined to select the optimal Rate Distortion (RD) cost of CTU [6,17]. Quad tree structure with multi type recursively partitions the slice and generate flexible block sizes [7,8]. In a video encoder, BjøntegaardDelta -Bit Rate (BD-BR) measurement is accustomed to compare the performance.…”