The case for predictable media quality in networked multimedia applications

Shared networks are now able to support a wide range of applications, including real-time multimedia This has led the networking community to consider a wider range of network Quality of Service (QoS) guarantees and pricing schemes. To date, the QoS required by networked multimedia applications has been described in terms of technical parameters. We argue that, in order to maximize the realized quality of any network, the QoS requirements of networked multimedia applications should be based on the value that users ascribe to the media quality they receive in the context of a particular task. This argument is supported with results from a set of studies in which users' perceptions of media quality was investigated for a listening task. We found that users' expectancies of quality directly influenced their ratings: low expectancies produce higher ratings for the same level of objective quality - provided that quality is predictable. In conclusion, we outline the implications of our studies for the design of networked multimedia applications and the network services that support them