Block Partitioning Structure in the VVC Standard

Abstract

Versatile Video Coding (VVC) is the latest video coding standard jointly developed by ITU-T VCEG and ISO/IEC MPEG. In this paper, technical details and experimental results for the VVC block partitioning structure are provided. Among all the new technical aspects of VVC, the block partitioning structure is identified as one of the most substantial changes relative to the previous video coding standards and provides the most significant coding gains. The new partitioning structure is designed using a more flexible scheme. Each coding tree unit (CTU) is either treated as one coding unit or split into multiple coding units by one or more recursive quaternary tree partitions followed by one or more recursive multi-type tree splits. The latter can be horizontal binary tree split, vertical binary tree split, horizontal ternary tree split, or vertical ternary tree split. A CTU dual tree for intra-coded slices is described on top of the new block partitioning structure, allowing separate coding trees for luma and chroma. Also, a new way of handling picture boundaries is presented. Additionally, to reduce hardware decoder complexity, virtual pipeline data unit constraints are introduced, which forbid certain multi-type tree splits. Finally, a local dual tree is described, which reduces the number of small chroma intra blocks.

Energy Efficient Video Decoding for VVC Using a Greedy Strategy-Based Design Space Exploration

“…The block partitioning that is used by VVC is presented in [23]. The authors show that the usage of the binary tree and ternary tree partitioning has a huge influence on the compression efficiency and encoding time (over 6-times compared to HEVC), but little influence on the decoding time, which increases in the range of 2-4 %.…”

VVC Search Space Analysis Including an Open, Optimized Implementation

“…In HEVC with only one split available the number of tested blocks increases with the depth, but the number of samples within a block decreases, effectively resulting in a linear relationship of maximal partitioning depth and overall number of processed samples, as will be shown further. For VVC, with multiple competing splits at each level [22], the growth is exponential again. Within this search, the encoder can make decisions based on heuristics, i.e.…”

Versatile Video Coding Standard: A Review from Coding Tools to Consumers Deployment

“…For the block partitioning, in addition to the principals explained in previous section, a new tool called dual-tree is introduced which allows separate partitioning trees for luma and chroma channel types. As opposed to the single-tree partitioning used in inter coding, the intra-specific dual-tree tool offers a higher level of freedom for coding decisions of chroma blocks [14].…”