Introduction
For a comprehensive assessment of walking disorders in a context of rehabilitation medicine, we developed a system for movement analysis based on multimedia technology, SYBAR [1,2]. This system synchronizes digitized video recordings of human behavior (e.g. walking) with digitized kinesiological signals (e.g. ground reaction force, EMG, joint angles). SYBAR is a Windows application written in C++. In order to make it possible to view the data sets of the SYBAR system with an Internet browser, we developed an HTML viewer based on a JAVA applet.

Method
The applet is started and receives input parameters in an HTML tag. Two of these input parameters are the URLs of the video (AVI format) and the synchronized data files. The format of the data files was taken from the SYBAR system. Video and kinesiological signals are coupled by means of a time code, which is written on the video frames as Vertical Interval Time Code (VITC), and is also stored in the data files. The graphical user interface of the applet contains a video player and figures with kinesiological data, in which a vertical time line shows the present video position (see Figure 1). Synchronization of video and kinesiological data is taken care of by regular updating of the time line of the figures to the time of the video player. The user can adjust the time of the video player not only with the control panel of the video, but also by mouse clicks in the figures.

Evaluation
The viewer was used to report the results of the analysis of the human movement lab to the referring physician over the hospital's computer network. A future use of the HTML viewer involves a client-server application suitable for multiple users across the Internet, which can be used for tele-consulation and tele-education.

Figure 1. The graphical user interface of the HTML viewer as it appears in a web browser. The time lines in the figures with kinesiological data are synchronized with the video player. Video time can be set by mouse clicks in the figures.

References

1. Harlaar, J.; Redmeijer, R.A.; Tump, P. (1998). The SYBAR motion analysis system: integrated recording and display of video, EMG and force-plate data. In: Measuring Behavior '98. Proc. 2nd Int. Conf. on Methods and Techniques in Behavioral Research (18-21 August 1998, Groningen, The Netherlands), 150-151.
2. Harlaar, J.; Redmeijer, R.A.; Tump, P.; Peters, R.; Hautus, E. (2000). The SYBAR system: Integrated recording and display of video, EMG, and force plate data. Behavior Research Methods, Instruments & Computers, 32, 11-16.

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