Falkowski-Gilski, Przemysław; Uhl, Tadeus; Divakarachari, Parameshachari Bidere
(Scientific Journals Maritime University of Szczecin, Zeszyty Naukowe Akademia Morska w Szczecinie,
)
Recently, many researchers have been intensively conducting quality of service (QoS), quality of experience
(QoE), and user experience (UX) studies in the field of video analysis. This paper is intended to make a new,
complementary contribution to this field. Currently, streaming platforms are key products in relation to delivering video content online. Most often, they include the MP4 video format, which is most widely utilized among
audio-visual codecs. This study involves a group of 38 individuals, aged between 21–35 years old, in a laboratory consisting of 20 iMacs with 4K retina display. The presented signal sequences included content sourced
from the Netflix Chimera repository, with 8- and 10-bit depth, available in different resolutions of 270p, 432p,
720p, and 1080p. Tests included a subjective quality evaluation in a 5-step mean opinion score (MOS) scale,
focused on the UX aspect. According to the obtained results, content with the lowest and highest resolutions is
optimal in 8-bit depth, while movies with intermediate resolutions are better in 10-bit depth. For 8-bit content,
the main problem is pixelation, whereas, in the case of 10-bit samples, the main issue is color noise, particularly
in the case of the lowest resolution. Many viewers indicated that 10-bit encoding offered lower quality. Moreover, 8-bit movies caused a lower quality of the gradient, presumably due to the smaller range of the available
color. However, 8-bit movies in the same situation generate visible stripes on static images in the background,
causing a lower quality of the gradient, which is probably due to the smaller range of available colors. The results of the performed experiments may be of particular interest to content creators and distributors, particularly
network and cable operators, as well as wireless and wired providers