The Effect of Content Desirability on Subjective Video Quality Ratings

Objective: The purpose of this study was to examine the impact of the desirability of content on viewers’ ratings of subjective video quality. Background: Most subjective video quality studies use short-duration clips that are specially designed to exercise the encoding algorithms and do not consider the desirability of the content as a variable. Method: In four studies, we employed a total of 100 participants and 180 movie clips encoded at nine levels from 550 kbps up to DVD quality. Participants viewed clips that were 2 min in length and then were asked about video quality of the clips and desirability of the movie content. Results: The results of these studies show that there is a strong correlation between the desirability of movie content and subjective ratings of video quality. This strong relationship holds across a wide range of encoding levels and movie content when that content is viewed under longer, more naturalistic viewing conditions. Conclusion: The effects of content should be considered when evaluating the subjective quality of encoded video content, as these effects can be as large as those seen between low- and high-quality encodings. Application: Researchers and practitioners trying to determine acceptable levels of video quality for actual consumption by consumers may find that the results and methods described here allow for a more accurate assessment of levels of video quality that are acceptable in a fielded service.