Subjective impression of variations in layer encoded videos

Layer encoded video is an elegant way to allow adaptive transmissions in the face of varying network conditions as well as it supports heterogeneity in networks and clients. As a drawback quality degradation can occur, caused by variations in the amount of transmitted layers. Recent work on reducing these variations makes assumptions about the perceived quality of those videos. The main goal of this paper respectively its motivation is to investigate the validity of these assumptions by subjective assessment. However, the paper is also an attempt to investigate fundamental issues for the human perception of layer encoded video with time-varying quality characteristics. For this purpose, we built a test environment for the subjective assessment of layer encoded video and conducted an empirical experiment in which 66 test candidates took part. The results of this subjective assessment are presented and discussed. To a large degree we were able to validate existing (unproven) assumptions about quality degradation caused by variations in layer encoded videos, however there were also some interesting, at first sight counterintuitive findings from our experiment.