Subjective Assessment of Adaptive Media Playout for Video Streaming

Adaptive Media Playout (AMP), the adaptive modification of media playback speed, has been previously proposed as a technique to modify the playout delay of a user with respect to other users or with real time, thus having a crucial role in social TV and live video streaming. In this paper, we study the subjective impact of the playout rate change, which had received very limited attention in the past. In particular, we analyze the effect of the subject and the source content in the subjective opinion.We have found that most of the previous works underestimated the impact of AMP in perceived quality, and that the speed change rate should not be modified beyond 10% from the original, as a general rule. We have also developed a user scoring model which takes into account the variability between users and sources. Our results can help developing cost models for playout control systems based on AMP, as well as provide some insights to the analysis of other types of subjective assessment tests.