User Assessment for Negotiating the Quality of Service for Streaming Media Applications

摘要

The increase of bandwidth and streaming technologies has made video on the Web viable. Streaming video services are still extremely delay sensitive, and network congestion can lead to poor video quality and end-user frustration. While attempting to deliver an optimal level of continuous media and network performance, the notion of Quality of Service (QoS) has emerged. Broadly, the notion of QoS is a reflection of user perception and determines the degree of satisfaction of a user with the video. One way to ensure that users get the QoS that they want for multimedia materials over the Internet is to give them control over the QoS on a dynamic basis at the desktop. A viewer can request and pay for higher, more consistent bandwidth as it is required to facilitate better quality audio and video. To design such a user interface, a user needs assessment was conducted to understand the user needs, problems and preferences when using and controlling streaming media applications over the Internet. Eight focus groups were conducted and during the discussions participants received different types of information on QoS issues. This information was either a visual demonstration, with video clips of different video compression and frame rates, or a verbal description of QoS issues. Two types of user interface examples for controlling QoS, one simple and one complex, were also presented during the discussion. Results shows a significant main effect of user attitudes towards QoS and a significant difference in ratings for five different video attributes. Participants thought it was important to control QoS and they are willing to control it, but they are not nearly as willing to pay to have better QoS. These ratings were generally true for different aspects of quality, except that color was rated lower than frame rate, audio/video synchronization, resolution and image size. Recommendations for including the capability to control QoS and for the QoS user interface are presented. The impact of video quality examples and user interface examples, as part of focus-group methodological issues, are presented as well.