Quality of Experience in Video Telephony : A Comparative Study of PEVQ and POLQA

Sammanfattning

This thesis investigates the impact of video and audio impairments on user experience in video telephony. Understanding Quality of Experience (QoE) and algorithms for assessing user experience in such settings has become increasingly important with the growing dependence on video telephony. This thesis aims to answer the question of how the PEVQ and POLQA subjective quality assessment algorithms compare to human subjective testing when it comes to various network degradations and if there is a dependency on the context at which the deterioration occurs in the video call. The tests were performed through subjective passive tests, having the testers rate a number of test conditions of network deteriorations on a MOS scale from 1-5, in regards to visual, audio, and audiovisual quality. These are later compared to corresponding PEVQ/POLQA MOS results. The results showed an initial incoherent relationship between subjective testing and the algorithm in regards to burst jitter and packet loss, but the results were later improved through a normalisation process, which clarified the results and discovered coherence between the scores. Conditions related to varying bitrates, varying resolutions and discards were in the initial results already quite coherent. The findings in this thesis work bear significance in the field of algorithmic QoE assessment, and may also contain some relevance in the field of bandwidth optimisation and QoE in regard to AI-generated content.