Yin-ji Piao

Coding efficiency comparison of new video coding standards: HEVC vs VP9 vs AVS2 video

In this paper, coding efficiency comparisons of emerging video codecs, HEVC, VP9 and AVS2 Video, are conducted. The purpose of this paper is to provide useful information about the current state-of-the-art video codecs and to help both academia and industry to get insight for developing advanced techniques on top of them. At first, design differences among the three video codecs are given briefly and then coding efficiency comparisons are conducted in random access and low delay condition. According to experimental results, HEVC outperforms VP9 and AV2 video by 24.9% and 6.5% in random access condition, respectively. In low delay condition, HEVC also outperforms VP9 and AVS2 video by 8.7% and 14.5%, respectively.

Coding efficiency improvements beyond HEVC with known tools

In this paper, several coding tools are evaluated on top of the HEVC version 1. Among them there are straightforward extension of HEVC coding tools (such as Coding Unit size enlarging, fine granularity of Intra prediction angles) and algorithms that have been studied during HEVC development (such as secondary transform, multi-hypothesis CABAC, multi-parameter Intra prediction, bidirectional optical flow). Most of them improve performance of Intra coding. Minor adjustment to the final version of HEVC standard was done for efficient harmonization of the proposed coding tools with HEVC. Performance improvement observed from investigated tools is up to 7,1%, 9,9%, 4,5% and 5,7% in all-intra, random access, low-delay B and low-delay P test scenario (using HEVC common test conditions).

Intra coding of AVS2 Video Coding Standard

This paper gives an introduction to intra coding of the new generation of Audio Video Coding Standard (AVS2) video part, the latest video coding standard under the development of Audio Video Coding Standard (AVS) Workgroup of China. Started from the basic tools in the first generation of AVS (AVS1), new structures similar to the HEVC are employed in AVS2 in terms of coding unit, prediction unit and transform unit. Despite of similar structures, several new features such as short distance intra coding, non-squared quad-tree transform, secondary transform as well as two-level coefficient coding combined with angular prediction are also adopted in intra coding of AVS2. The coding efficiency of intra coding of AVS2 is improved by about 30% in BD-rate compared with AVS1 and achieves the similar performance to HEVC/H.265.

Sample adaptive offset in AVS2 video standard

AVS2 video standard is the next-generation video coding standard under the development of Audio Video coding Standard (AVS) workgroup of China. In this paper, the design of Sample Adaptive Offset (SAO) in AVS2 is presented. Considering the implementation issues, a shifted structure in which the SAO parameter region is shifted from the Largest Coding Unit (LCU) to the upper-left is adopted to make the SAO parameter region consistent with the processing region in implementation. Moreover, the category dependent offset is introduced in the edge type based on the statistical results to improve the offset coding and non-consecutive offset bands are adopted in the band type to optimize offset bands. The test results show that SAO achieves on average 0.3% to 1.4% luma coding gain in AVS2 common test conditions.