Towards Video Quality of Experience and Selective Attention: A Subtitle-Based Measurement Study

Selective attention is the idea that visual attention is not granted equally to all regions of the visual field, but rather focuses on high-attention regions. In this paper, we propose that selectively improving the performance of video in regions that are given high attention by users can significantly improve the quality of experience (QoE) of video services. We investigate users' attention regions, and choose the subtitle region as a representative high-attention region to present a subtitle-based measurement study. This study concentrates on how and how much the subtitle region affects the QoE of video. First of all, we verify that changes in performance of the subtitle region can cause an illusion about users' judgment on video bitrate. Secondly, we present a logarithmic relationship between video bitrate and the QoE of video. Thirdly, we measure the improved QoE by improving the performance of the subtitle region. Finally, we demonstrate that selectively improving the performance of the subtitle region can significantly improve the QoE of video at little cost.