A Psychophysical Evaluation of Frame Rate in Desktop Video Conferencing

Abstract

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.

Get full access to this article

View all access options for this article.

References

Apteker

R. T.

Fisher

J. A.

Kisimov

V. S.

Neishols

(1994). Distributed multimedia: user perception and dynamic QoS. In Proceedings of SPIE, 2188, 226–234. Bellingham, WA: The International Society for Optical Engineering.

Chuang

S. L.

Haines

R. F.

(1993). A study of video frame rate on the perception of compressed dynamic imagery. In Society for Information Display '93 Digest. (pp. 524–527).

Engen

(1971) Psychophysics II. scaling methods. In Kling

J. W.

Riggs

L. A.

(Eds.) Woodsworth & Schlosberg's Experimental Psychology, Third Edition. New York, NY: Holt, Rinehart, and Winston.

Gescheider

G. A.

(1985) Psychophysics: Method, theory, and application. Hillsdale, NJ: Lawrence Erlbaum Associates, Inc.

Howell

D. C.

(1992) Statistical methods for psychology, third edition. Belmont, CA: Duxbury Press.

Keppel

(1991) Design and analysis: A researcher's handbook. (3rd Ed.). Englewood Cliffs, NJ: Prentice-Hall.

Kies

J. K.

(1997) Empirical methods for evaluating video-mediated collaborative work. Unpublished Doctoral Dissertation. Blacksburg, VA: Virginia Polytechnic Institute and State University.

Kies

J. K.

Williges

R. C.

Rosson

M. B.

(in press) Evaluating desktop video conferencing for distance learning applications. Computers and Education.

Masoodian

Apperley

Fredrickson

(1995) Video support for shared work-space interaction: an empirical study. Interacting with Computers, 7(3), 237–253.

10.

O'Conaill

Whittaker

Wilbur

(1993) Conversations over video conferences: an evaluation of the spoken aspects of video-mediated communication. Human-Computer Interaction, 8, 389–428.

11.

Pappas

T. N.

Hinds

R. O.

(1995). On video and audio integration for conferencing. In Proceedings of SPIE, Vol. 2411. Bellingham, WA: The International Society for Optical Engineering.

12.

Sellen

A. J.

(1992). Speech Patterns in Video-Mediated Conversations. In CHI '92: Human Factors in Computing Systems (pp. 49–59). New York, NY: The Association for Computing Machinery.

13.

Stevens

S. S.

(1975) Psychophysics: Introduction to its perceptual, neural, and social prospects. New York, NY: John Wiley & Sons.

14.

Swartz

Wallace

Tkacz

(1992). The influence of frame rate and resolution reduction on human performance. In Proceedings of the Human Factors and Ergonomics Society 36th Annual Meeting (pp. 1440–1444). Santa Monica, CA: Human Factors and Ergonomics Society.

15.

Tang

J. C.

Isaacs

(1993). Why do users like video? studies of multimedia-supported collaboration. Computer Supported Cooperative Work (CSCW), 1, 163–193.