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.

The emerging standards for screen content coding (SCC) and 3D video coding known as High Efficiency Video Coding (HEVC)-SCC and 3D-HEVC, respectively, have been developed as extensions of HEVC. Compared with camera-captured video, screen content video and depth maps usually contain significantly fewer colors or sample intensities and much sharper edges in a frame. In this paper, a new coding method named segmental prediction is proposed to code screen content and depth maps more efficiently. First, samples in a prediction block are classified into several segments according to the sample intensities. Second, a particular predictor is calculated for each segment. Then an offset for a segment is derived at the encoder side and signaled to the decoder side. Finally, a single sample value is assigned to each segment in the reconstructed block. The experimental results show that the proposed approach can achieve a 2.2% average Bjontegaard Distortion-rate (BD-rate) saving under the HEVC-SCC common test conditions (CTCs) for sequences of the category YUV, text and graphics with motion, 1080p, with the all intra configuration. It can also achieve a 0.6% average BD-rate saving for synthesized views under the 3D-HEVC CTCs with the random access configuration.

The 3D extension of High Efficiency Video Coding (3D-HEVC) is a new international video coding standard that has been developed by the Joint Collaborative Team on 3D Video Coding Extensions (JCT-3V). It aims at improving the coding efficiency of 3D and multi-view videos by introducing new coding tools to utilize the correlations between views and between texture and depth components. In this paper, we propose an inter-view motion prediction (inter-view merge candidate) and an inter-component motion prediction (texture merge candidate) to explore the inter-view and the inter-component redundancies. The proposed schemes were adopted in 3D-HEVC and the experimental results demonstrate that the proposed inter-view merge candidate and texture merge candidate achieve significant BD-rate reductions of 20% for dependent texture views and 9% for the synthesized texture views under the common test conditions used for 3D-HEVC standardization.

In the screen content coding extension for HEVC, intra block copy (IBC) was adopted to explore the redundancy between reduplicated patterns, which often occurs in a picture with screen contents. Besides reduplication, symmetry is also often observed in screen-content and even in natural pictures. In this paper, symmetric intra block copy (SIBC) is therefore proposed to further improve IBC. By flipping the reference block of IBC horizontally or vertically, SIBC may provide better predictions than IBC for symmetric patterns. Experimental results show that SIBC can achieve 1.2% and 1.9% coding gains in all intra configurations on sequences in the category of YUV, text & graphics with motion, 1080p for lossy and lossless coding respectively.

High Efficiency Video Coding (HEVC) adopts hybrid transform coding scheme to improve the transform performance. However, it does not consider the influence of the prediction unit boundary. This paper proposes an adaptive boundary dependent transform optimization scheme for HEVC. Based on the transform unit boundary type identification by checking whether it lies at a prediction unit boundary or not, some additional transform kernels, including DCT-IV, are incorporated for transform. Moreover, the additional adopted transform kernels are generated by re-using the existing kernels in HEVC. Therefore, the butterfly structure for transform implementation can be preserved to facilitate parallel computing, and computational complexity increasing can be avoided. Experimental results show that the coding performance improvements can be up to 0.96% and 0.64% for low delay P and random access testing configurations respectively.

This paper presents a novel inter-view motion prediction technique used in 3D-HEVC which provides efficient compression for motion vectors. The 3D extension of HEVC (High Efficiency Video Coding) namely 3D-HEVC is under development in JCT-3V for coding multi-view video and depth data. Inter-view motion prediction takes benefit of the inter-view correlation between views by inferring the motion information of a view from the already coded motion information in another view as well as the local disparity between two views. Experimental results show that inter-view motion prediction in 3D-HEVC provides an average bit-rate savings of 15% for the dependent views.

Recent years we have witnessed a striking rise of the compound video, which is generated by computers. The High Efficiency Video Coding standard (HEVC) adopts the intra transform skip mode to improve the coding efficiency of compound video. In this paper, we improve the intra transform skip mode from two aspects. Firstly, we study the statistical character of the intra prediction residual and propose a separate coefficient scan order for the intra transform skip mode. Secondly, we analyze the probability of the intra transform skip mode for different coding unit (CU) sizes and prediction unit (PU) sizes, and then propose one limitation to reduce the applied range of intra transform skip mode. The experimental results show that the first method can achieve 1.6%, 1.1%, and 0.7% luma coding gains on average in terms of BD-rate for class F under HE10-AI, HE10-RA, and HE10-LB conditions respectively; the second method can bring 9% encoder run time reduction with almost the same BD-rate changes. The proposed methods have been partially adopted into HEVC standard.

This paper proposes a progressive motion vector resolution (PMVR) method for High Efficiency Video Coding (HEVC). In the proposed scheme, high motion vector (MV) resolutions, e.g. 1/4 or 1/8 pixel resolution, are employed for MVs near to the motion vector predictor (MVP) and low MV resolutions are employed for MVs far from the MVP. The range of each MV resolution is indicated by a threshold parameter. And a new motion vector difference (MVD) derivation method is designed to encode MVD efficiently. Experimental results show that PMVR with 1/8 pixel motion search can achieve a BD-rate gain up to 16% with almost the same coding time with HM8.0, and for PMVR without 1/8 pixel motion search, up to 6.1% BD-rate gain can be achieved with 9% encoding time saving on average.

Recently, an efficient coding tool named adaptive interpolation filtering (AIF) has been proposed to hybrid video coding scheme. By introducing Wiener filter into the fractional-pixel interpolation procedure, AIF can reduce the inter-prediction error and improve coding efficiency significantly. However, the training-based Wiener filter mechanism brings AIF an inherent multi-pass encoding structure, which imposes big burdens on the encoder in terms of huge computational complexity and memory access. In this paper, we propose a single-pass-based localized adaptive interpolation filtering (SPL-AIF) algorithm for video coding, which can reduce the complexity of AIF dramatically without sacrifice of its outstanding coding performance. The proposed SPL-AIF algorithm is based on the observation that there is a high correlation among optimal interpolation filters of consecutive frames, and different regions in a frame often possess different statistical characteristics. Accordingly, the proposed algorithm can be designed including two major parts. First, a competitive filter set which includes the optimal interpolation filters of several previous frames as well as the fixed H.264/AVC interpolation filters is built up for the coding of the current frame. Then a rate-distortion optimization criterion is used to select the best one at macroblock (MB) level. In order to reduce overhead, a predictive coding method is used to compress the filter signaling flag for each MB. Experimental results show that, by using the proposed algorithm, the encoding complexity can be reduced significantly while the average coding gain in Bjöntegaard distortion bit-rate reduction can be improved about 1% compared with the multi-pass AIF. The proposed method has been adopted into the Video Coding Expert Group Key Technology Area software.

Adaptive interpolation filtering (AIF) algorithms have been proposed to enhance the hybrid video coding scheme recently. Although these algorithms can improve coding efficiency significantly, their encoders suffer huge increase in complexity in terms of latency and memory access due to its inherent multi-pass encoding procedure. In this paper, we present a novel single-pass solution for these algorithms, which allows optimal selection among different interpolation filters. In this solution, time-delayed interpolation filters are used to achieve single-pass encoding, and localized ratedistortion (RD) selection is used to compensate the possible coding loss from time-delayed filters. Experimental results show that the proposed method is efficient for All AIF techniques in current ITU-T/SG16 reference software. By using the proposed method, single-pass encoding with multiple AIF filters can be achieved while maintaining similar coding efficiency as multi-pass AIF.

In this paper, we propose a context-based inverse quantization and show its application in wavelet image compression. The proposed method breaks the traditional one-to-one mapping of the quantization index to reconstruction value in inverse quantization while maps an index to several different reconstruction values according to the corresponding contexts of the index. By accurate context modeling, this method can reduce the quantization distortion significantly. Since the quantization indices used for encoding is not changed, this method does not increase the encoding bit rates except the negligible overhead.

This letter introduces a simple yet efficient rate control method, which is designed for lossless mode of JPEG2000. This method uses a fractional upward shift of bitplane to simulate more precise subband weighting. Compared to the previous integer upward shift of the bitplane, it achieves superior performance at most bit-rates without the cost of increased computational complexity.

A modified embedded trellis coded quantization (TCQ) for JPEG2000 is presented in this paper. The method for approximately inverting TCQ in the absence of the least significant bits is improved. Experimental results, presented using the optimal rate control algorithm and different embedded TCQ formulations, show that modified embedded TCQ yields significant performance improvement compared to the original one in JPEG2000.