Perceptual Quality Assessment of HEVC and VVC Standards for 8K Video

Abstract

With the growing data consumption of emerging video applications and users' requirement for higher resolutions, up to 8K, a huge effort has been made in video compression technologies. Recently, versatile video coding (VVC) has been standardized by the moving picture expert group (MPEG), providing a significant improvement in compression performance over its predecessor high efficiency video coding (HEVC). In this paper, we provide a comparative subjective quality evaluation between VVC and HEVC standards for 8K resolution videos. In addition, we evaluate the perceived quality improvement offered by 8K over UHD 4K resolution. The compression performance of both VVC and HEVC standards has been conducted in random access (RA) coding configuration, using their respective reference software, VVC test model (VTM-11) and HEVC test model (HM-16.20). Objective measurements, using PSNR, MS-SSIM and VMAF metrics have shown that the bitrate gains offered by VVC over HEVC for 8K video content are around 31%, 26% and 35%, respectively. Subjectively, VVC offers an average of around 41% of bitrate reduction over HEVC for the same visual quality. A compression gain of 50% has been reached for some tested video sequences regarding a Student's t-test analysis. In addition, for most tested scenes, a significant visual difference between uncompressed 4K and 8K has been noticed.

Modeling Perceived Quality on 8K VVC Video Under Various Screen Sizes and Viewing Distances

“…We down-converted the 8K videos to 2K (1,920×1,080), 4K, and 6K (5,760×3,240) spatial resolutions with the same 60 Hz temporal framerate to generate distorted videos. For all the down-and upconversion processes, the Lanczos-3 filter [14] using FFmpeg 3 was applied according to previous studies [5], [15]. Next, we load the down-converted and 8K original videos to the encoder.…”

“…The actual bitrates and QP values are shown in Table 2. A previous study on 8K subjective evaluations revealed that VVC exhibits an average of approximately 41% of bitrate reduction over HEVC for the same visual quality [5]. Therefore, we considered that target bitrates widely cover video quality from low to high in this range.…”

“…We used the 8K original videos as a reference input of the metrics. The performance of the objective metrics was evaluated similarly to previous related studies [5], [24]. The consistency between the metric values and the subjective evaluation results was investigated by the logistic curve fitting based on the least square method as follows:…”

“…Meanwhile, the versatile video coding (VVC)/H.266 [4] was standardized in 2020 as the subsequent video coding scheme of HEVC. Bonnineau et al [5] conducted subjective assessments on both 8K HEVC and VVC encoded videos and reported that VVC exhibits an average of approximately 41% of bitrate reduction over HEVC for the same visual quality. Thus, VVC can become a dominant technique for delivering high-quality UHD videos at considerably lower bandwidth, such as terrestrial transmission.…”

“…However, such studies are yet to be performed on 8K videos, whose optimal viewing distance is 0.75 H [13] for an immersive experience. For example, Bonnineau et al [5] conducted subjective evaluations on 8K VVC encoded videos with only one condition, using an 85-inch 8K TV and viewing at the optimal viewing distance.…”