Fast Intra Mode Decision Algorithm for Versatile Video Coding
Fast Intra Mode Decision Algorithm for Versatile Video Coding
复制标题
适用于多功能视频编码的快速帧内模式决策算法
DOI：
10.1109/tmm.2021.3052348
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发表时间：
2022-01-01
影响因子：
7.3
通讯作者：
Yang, Hao
中科院分区：
文献类型：
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作者：
Dong, Xinchao;Shen, Liquan;Yang, Hao
为了提高编码效率，最新的通用视频编码（Versatile Video Coding，VVC）标准采用了一系列新的帧内编码技术，包括四叉树加多类型树（quadtree plus multi-type tree，QTMT）、帧内子分区（intra sub-partitions，ISP）和帧内块复制（intra block copy，IBC）。然而，这使得帧内编码更加复杂，因为VVC需要遍历QTMT的所有预测模式和分区类型以找到最佳组合。本文从模式选择和预测终止两个方面提出了一种快速变值压缩算法，以降低编码复杂度。在模式选择方面，提出了自适应模式剪枝（AMP）算法，去除非期望模式。首先，由于新引入的模式（IBC和ISP）并不是对所有块都有效，因此基于学习的分类器被设计为智能地去除它们。其次，对于正常模式，提出了一种集成决策策略，对候选模式进行排序，并增加前几个候选模式成为最优模式的概率，从而可以更有效地去除冗余候选模式。在预测终止方面，我们发现当前深度水平的不同最佳模式导致剩余帧内预测的不同终止概率。因此，提出了模式相关终止（MDT），通过最优模式选择合适的模型，并终止剩余深度级别的不必要的帧内预测。在VVC测试模型上实现了该算法，仿真结果表明，在BDBR仅增加0.93%~ 1.08%的情况下，该算法可以获得51%~ 53%的时间节省.
To achieve higher coding efficiency, the latest Versatile Video Coding (VVC) standard adopts a series of new intra coding techniques, including the quadtree plus multi-type tree (QTMT), intra sub-partitions (ISP) and intra block copy (IBC). However, this makes the intra codingmore complicated, asVVCneeds to traverse all prediction modes and partition types of QTMT to find the optimal combination. In this paper, we propose a fast algorithm for VVCfromtwo aspects ofmode selection and prediction terminating to reduce coding complexity. For the mode selection, adaptive mode pruning (AMP) is proposed to remove non-promisingmodes. First, since the newly introduced modes (IBC and ISP) are not effective for all blocks, learning-based classifiers are designed to remove them intelligently. Second, for normal modes, an ensemble decision strategy is proposed to sort the candidate modes and increase the probability of being the optimal mode for the first few candidates; thus, we can remove redundant candidates more efficiently. In terms of prediction terminating, we find that different optimal modes of current depth level lead to different termination probabilities of remaining intra predictions. Therefore, modedependent termination (MDT) is proposed to select an appropriate model through the optimal mode and terminate unnecessary intra predictions of remaining depth levels. The proposed algorithm is implemented on VVC test model, and simulation results show that it can achieve 51%similar to 53% time savings with only 0.93%similar to 1.08% BDBR increases.