In this letter, fast intra mode decision algorithms for HEVC Screen Contents Coding (SCC) are proposed. HEVC SCC has been developed to efficiently code mixed contents consisting of natural video, graphics, and texts. Comparing to HEVC version 1, the SCC encoding complexity significantly increases due to the newly added intra block copy mode. To reduce the heavy encoding complexity, the evaluation orders of multiple intra modes are rearranged and several early termination schemes based on intermediate coding information are developed. Based on our evaluation, it is found that the proposed method can achieve encoding time reduction of 13∼30% with marginal coding gain or loss, compared with HEVC SCC test model 2.0 in all intra (AI) case.

In this letter, methods of inactive regions padding for Segmented Sphere Projection (SSP) of 360 videos are proposed. A 360 video is projected onto a 2D plane to be coded with diverse projection formats. Some projection formats have inactive regions in the converted 2D plane such as SSP. The inactive regions may cause visual artifacts as well as coding efficiency decrease due to discontinuous boundaries between active and inactive regions. In this letter, to improve coding efficiency and reduce visual artifacts, the inactive regions are padded by using two types of adjacent pixels in either rectangular-face or circle-face boundaries. By padding the inactive regions with the highly correlated adjacent pixels, the discontinuities between active and inactive regions are reduced. The experimental results show that, in terms of end-to-end Weighted to Spherically uniform PSNR (WS-PSNR), the proposed methods achieve 0.3% BD-rate reduction over the existing padding method for SSP. In addition, the visual artifacts along the borders between discontinuous faces are noticeably reduced.