Banding is a visually unpleasing artifact appearing in flat areas of encoded content that no video standard has fully addressed. We propose a normative debanding filter to tackle banding artifacts and have tested it as an inloop and post-loop filter in AVM. Debanding is achieved by introducing dithering on a frame level to the luma component. The proposed filter shows CAMBI gains for content with banding while not affecting other content. Although the added dithering has a minor negative impact on some objective metrics, subjective improvements in banding-prone content are (informally) observed. On the test set, encoding time increases on average by ~0.5%, while decoding time increases by around 0.5% for in-loop and 1.5% for post-loop.

This paper presents a method for efficient compression of high dynamic range (HDR) and wide color gamut (WCG) video data. The proposed solution consists of two major elements: a conventional video codec (e.g., HEVC) and pre-and post-processing steps applied prior to encoding and after decoding process, respectively. The proposed HDR/WCG video coding system can be configured to provide two configurations: (1) a non-backward compatible bitstream with improved HDR video quality and (2) a SDR backward compatible bitstream with balanced visual quality between the reconstructed signal by the SDR and the HDR receivers. The simulations conducted under the MPEG Common Test Conditions for HDR demonstrate that the compression efficiency of the proposed solution outperforms the anchor solution on objective metrics. Additionally, subjective evaluations conducted under MPEG revealed improved visual quality for the proposed method.

Summary form only given. Screen content videos increasingly gain the popularity due to the rapid advances in cloud and multimedia technologies, which in turn requires highly efficient screen content compression. A recent standard, namely SCC is under development in JCT-VC, Joint Collaborative Team on Video Coding between ISO/IEC and ITU-T. In SCC, the most efficient new coding tool is Intra block copy (Intra BC). In this paper, we describe the Intra BC that has been proposed by the authors and adopted in the SCC standard and reference software for coding of screen content. Different from the conventional Intra prediction method where the prediction signal is derived from the spatially neighboring samples, the Intra BC mode greatly improves the prediction efficiency by fully exploiting the redundancy of repetitive patterns which typically appear in screen content. Experimental results suggest that the Intra BC mode can improve the coding efficiency significantly for typical screen content video sequences with 43.2% bit rate reduction on average.

This paper presents an in-loop adaptive color-space transform for the HEVC Screen Content Coding extension. In the proposed method, the prediction residual is adaptively converted into a different color space to reduce the cross-component redundancy. After the ACT, the signal is coded following the existing HEVC framework. To keep the complexity as low as possible, fixed color-space transforms that are easily implemented with shift and add operations are utilized. Significant coding gains are achieved by this method in the current HEVC Screen Content Coding reference software with no increase of decoding runtime. The proposed method has been adopted to the HEVC Screen Content Coding extension.

This paper describes a scalable video codec that was submitted as a response to the joint call for proposals issued by ISO/IEC MPEG and ITU-T VCEG on HEVC scalable extension. The proposed codec uses a multi-loop decoding structure. Several inter-layer texture prediction methods are employed to remove the inter-layer redundancy. Inter-layer prediction is also used when coding enhancement layer syntax elements such as motion parameter and intra prediction mode, to further reduce bit overhead. Additionally, alternative transforms as well as adaptive coefficients scanning are used to code the prediction residues more efficiently. Experimental results are presented to demonstrate the effectiveness of the proposed scheme. When compared to HEVC single-layer coding, the additional rate overhead for the proposed scalable extension is 1.2% to 6.4% to achieve two layers of SNR and spatial scalability.