Subjective preference of spatio-temporal rate in video adaptation using multi-dimensional scalable coding

Video adaptation allows for direct manipulation of existing encoded video streams to meet new resource constraints without having to encode the video from scratch. Multi-dimensional scalable coding such as motion-compensated subband coding (MCSBC) offers an effective and flexible representation for video adaptation. In order to develop robust criteria for selecting optimal spatio-temporal rates used in adaptation, knowledge about subjective preference of spatio-temporal rates is needed. In this paper we study the optimal temporal frame rate over a wide range of bandwidth (50 Kbps to 1Mbps) using subjective quality evaluation with 128 clips and 31 subjects. We analyze the results using statistical testing methods and investigate the dependence of optimal frame rate on user, bandwidth, and video content characteristics. Our findings indicate the agreement among most users and existence of switching bandwidths at which preferred frame rates change. Dependence of the preference on video content types is also revealed.