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.

This paper describes a video coding technology proposal submitted by MediaTek in April 2018 in response to a joint call for proposals (CfP) issued by ITU-T VCEG and ISO/IEC MPEG. The proposal uses the conventional block-based hybrid coding approach with a breakthrough design of block structure, substantial improvements of coding tools, and new inventions of loop filtering techniques. First, the block structure is designed using a highly flexible partitioning scheme, where each coding tree unit in a picture is split into multiple coding units (CUs) by a recursive quaternary tree followed by a recursive binary-ternary tree. The prediction unit (PU) and transform unit (TU) concepts are unified with the CU concept, i.e., PU and TU are basically the same as CU. Moreover, inter prediction, intra prediction, transform, quantization, in-loop filtering, and entropy coding are all improved. Finally, new loop filtering techniques are invented, where the proposed convolutional neural network loop filtering is of particular interest. The proposed video codec achieves 43.81% average bit rate savings based on objective measures compared to the High Efficiency Video Coding (HEVC) anchors and is among the best-performing CfP responses both objectively and subjectively. It has been partially adopted into the working draft of the Versatile Video Coding (VVC) standard.

This paper presents a new algorithm for reducing aliasing artifacts related to the conventional spatial scalable subband/wavelet coding for recovering video at lower resolution. The proposed scheme has been fully integrated with the H.264/AVC JSVM reference software and experimentally evaluated against the conventional methods for intraframe spatial scalable video coding. The simulation results show our method can effectively remove the aliasing artifacts for scalable decoding at lower resolution without performance penalty at full resolution.

This paper develops a new intra-frame dyadic spatial scalable coding framework based on a subband/wavelet coding approach for MPEG-4 AVC/H.264 scalable video coding (SVC). It is the first attempt in the literature to join the subband filter banks with the traditional macroblock and DCT based video coding system. We demonstrate that the current H.264 coding tools and syntax set can efficiently work together with the traditional subband filter banks for providing the improved efficiency for intra-frame dyadic spatial scalable coding. More importantly, unlike the classical wavelet coding, the proposed framework still allows the down-sampling filter to be flexibly designed to generate the ideal low resolution video for target applications. The proposed wavelet tool has been adopted by the JSVM for the next-phase SVC standard.

Three-dimensional (3-D) subband/wavelet coding with motion compensation has been demonstrated to be an efficient technique for video coding applications in some recent research works. When motion compensation is performed with half-pixel accuracy, images need to be interpolated in both temporal subband analysis and synthesis stages. The resulting subband filter banks developed in these former algorithms were not invertible due to image interpolation. In this paper, an invertible temporal analysis/synthesis system with half-pixel-accurate motion compensation is presented. We look at temporal decomposition of image sequences as a kind of down-conversion of the sampling lattices. The earlier motion-compensated (MC) interlaced/progressive scan conversion scheme is extended for temporal subband analysis/synthesis. The proposed subband/wavelet filter banks allow perfect reconstruction of the decomposed video signal while retaining high energy compaction of subband transforms. The invertible filter banks are then utilized in our 3-D subband video coder. This video coding system does not contain the temporal DPCM loop employed in the conventional hybrid coder and the earlier MC 3-D subband coders. The experimental results show a significant PSNR improvement by the proposed method. The generalization of our algorithm for MC temporal filtering at arbitrary subpixel accuracy is also discussed.

In this paper, we present a new embedded wavelet image coding system using quadtree splitting and context modeling. It features low computational complexity and high compression efficiency, thanks to joint utilization of two powerful embedded coding techniques-set partitioning and context modeling. With effective exploitation of strong statistical dependencies among the quadtree nodes built up from subband coefficients, the proposed algorithm substantially improves the coding efficiency of the existing set-partition coders for both lossy and lossless image compression. For example, our experimental results show that the new algorithm respectively outperforms zerotree-based SPIHT and quadtree-based SPECK by 0.7 dB and 1.0 dB at 0.5 bpp on an average.

With fast computation and excellent compression efficiency, two embedded coding techniques, zero-tree/-block coding and context modeling of the subband/wavelet coefficients, have been widely utilized for image coding applications. In this research, we present a new embedded wavelet image coding algorithm with an attempt to combine advantages of these two successful coding schemes. The experimental results show that the proposed algorithm outperforms the respected zero-tree/-block coders, SPIHT and SPECK, in compression efficiency. It is also comparable to the state-of-art JPEG 2000 test coder in PSNR performance while retaining the attractive low-complexity feature of the zeroblock coders.