Distributed multimedia: user perception and dynamic QoS

Dynamic QoS yields better network utilization by deliberately degrading the quality of existing continuous media connections so that new user requests can be accommodated. This distributed multimedia approach involves dynamically controlling multimedia parameters such as color depth, frame rate and audio sampling rate. It is obvious that a degradation of the physical characteristics of a real-time service will result in perceived differences in video acceptability. But not so obvious is the relationship between video message importance and video degradation. Through experiments it is possible to gain insight as to what type of distributed video applications will be more susceptible to a degradation in the QoS. This paper examines the effects that dropping the frame rate of a video window has on user perception. Findings support the fundamental premise that frame rate reduction itself leads to progressively lower ratings of acceptance, which erodes with each stepwise decrease in the experimental frame rates. We describe the results in terms of network bandwidth and distributed video applications. Dynamic QoS is by no means an intermediate step in the realization of unconstrained multimedia on-demand services. Adaptive algorithms will continually be required since there is no upper bound on the complexity of user requirements.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.