A psychophysical evaluation of frame rate in desktop video conferencing

The quality of digital video transmitted over computer networks can suffer from a variety of degradations. Little research has addressed perceptions of degraded digital video image quality. This paper reports on a study in which a psychophysical method, magnitude estimation, was used to develop a ratio scale of image quality for frame rates between 1 and 28 frames per second (fps). Five different scenes were used as stimuli, each varying in terms of filming speed, level of detail, and content. Results indicate that for non-traditional conferencing applications, image quality is not perceived to be better at rates greater than 10 fps. For a traditional conferencing application, a linear increase in image quality perception is associated with a linear increase in frame rate. Results are presented in terms of trend analysis, Steven's Power Function, and parametric statistics. Implications are made for the design of multimedia communication networks.