N16882, Verification Test Report for HEVC Screen Content Coding Extensions

This document presents a test report on verification of the coding performance of the HEVC screen content coding (SCC) extensions. The coding performance of HEVC screen content model (SCM) reference software with the SCC extensions enabled is compared with that of HEVC test model (HM) without the SCC extensions, as well as with the AVC joint model (JM) reference software in both lossy and mathematically lossless compression modes using All-Intra (AI), Random Access (RA), and Low-delay B (LB) encoding structures and using similar encoding rate-distortion optimization techniques. Six test sequences are used in the test, which have been classified into two categories, namely “text and graphics with motion” (TGM) and “mixed content” (M). The test bitstreams were generated in the RGB 4:4:4, YCbCr 4:4:4, and YCbCr 4:2:0 colour sampling formats with 8 bits per sample. For lossless coding, the performance of the JM, SCM, and HM are evaluated in terms of relative bit-rate savings. For lossy compression, subjective testing was conducted at 4 quality levels for each coding case, and the test results are presented through mean opinion score (MOS) curves. The relative coding performance has also been evaluated in terms of Bjøntegaard-delta (BD) bit-rate savings for equal PSNR objective quality using all 648 subjective test points. The perceptual tests as well as objective metric measurements showed very substantial benefit in coding efficiency for the screen content coding extensions, and provided consistent results with a high degree of confidence. For TGM video, the estimated bit-rate savings for lossy and lossless coding ranged from 60–90% relative to the JM and 40–80% relative to the HM, depending on the AI/RA/LB configuration category and colour sampling format.