ClearBoard is a technology demonstration that illustrates a new concept in video-based collaboration. It also demostrates the collaboration potential of a workstation like the O2, which has real-time compression and high speed networking buit in to it.
Just to clear up some confusion: this page is, for the most part, dedicated to the O2 implementation of the demo which is also known as "MediaConf".
The basic idea behind Clearboard is the ability to transmit live video over a network between 2 (and eventually more than 2) users. Annotations can be performed on top of the video feed to facilitate collaboration on whatever the subject might be. The video streams can be of 3 main types:
Live video - from a camera or any other video source (eg VTR). This allows collaborative work on anything you can point a camera at, or store to video tape.
Movie File - Quicktime and SGI movie files which are compressed using the JPEG codec can be played back over the network. Shared movie transport controls can be used to allow either user to scrub through the movie and annotate on top of any frame.
Screen Capture - This is the form of collaboration from which Clearboard got it's name. Any portion of the user's screen can be captured, compressed and sent over the network. This means that you can be running any application, and lay the "Clearboard" on top of it to make it collaborative. Annotations can be made, right on top of the application, or the application can be used, as normal, while others watch and comment on the use. You can toggle between annotation and user mode with the touch of a button.
The other main difference between Clearboard and traditional video conferencing packages is the quality and type of video that is used. The video can be full, NTSC resolution video, with as low of a compression ratio as 4:1. While this type of resolution requires a large amount of network bandwidth, this level quality is required by certain professionals in industries such as video post-production and special effects. Clearboard also offers the flexibility to work with highcompression ratios and smaller video sizes to decrease the network traffic it generates (see the Bandwidth and Image Quality section for more detailed information on the tradeoffs).
The Java client for MediaConf currently only supports playback of video broadcast from MediaConf running on an O2. However, in screen capture mode, annotations are captured along with the frame and so are also visible in the Java client. The Java client interface functions the same as the O2 client. Simply select a "Channel" (a video source) and you're seeing video. In addition to the O2 client interface, the Java client contains a status bar that indicates when new video sources have registered themselves and a frame rate monitor.
MediaConf for Java requires the Java Development Kit (JDK) versions 1.1.x. For IRIX, the JDK 1.1.x is supported in CosmoCode 2.2 and later. The current version of MediaConf for Java is known NOT to run with Microsoft's SDK 2.0beta (Microsoft does not ship all of Sun's extra libraries). Sun's JDKs and JREs for Solaris and Windows95/NT are known to work with MediaConf for Java.
Concerning performance: On IRIX, the JRE load-time is significantly faster than using the standard Java interpreter (java). MediaConf for Java is a software-only solution so faster CPUs yield better performance. On PCs and laptops, low memory configurations may make the Java client unstable (i.e. the Java stack runs out of space). I would recommend no less than 32MB of RAM on Windows95/NT. WindowsNT generally performs better than Windows95 (due to lots of thread context switching in the Java client) and is rather speedy on dual-Pentium configurations.
Ed Allard, Silicon Graphics
Last Update, Dec 10, 1997