Investigation of the Relationship between Subjective and Objective Video Quality Metrics for Multiparty Video Calls on Mobile Devices

Today, various solutions and configurations exist for enabling audiovisual communications. One of the main driving forces has been the evolution of the technologies and APIs related to the open source WebRTC standards, enabling browser-to-browser real-time communication with built-in real-time audio and video functions without requiring any plugins. However, given the strict delay and high bandwidth requirements associated with video conferencing services, along with variable mobile network resource availability and limited mobile end user device capabilities, challenges arise in terms of setting and adapting video encoding parameters so as to achieve acceptable end-user perceived quality. In this paper, we extend our previous studies with further exploration of the impact of different video encoding parameters on perceived video quality. Furthermore, we focus on investigating the relationship between subjective video quality ratings and selected objective video quality metrics (namely blurriness and blockiness) to determine to what extent objective metrics correlate with subjective scores in the specific context of multiparty video calls on mobile devices. Our findings, reported based on the results of a user study (n=27), indicate that perceived video quality has very strong and strong correlation with objective blockiness and blurriness values, respectively.