
		AT&T Laboratories Cambridge

The Videotile

The Videotile (or simply "tile") is a display device that plugs directly into the ATM network. The Tile has a backlight colour active matrix liquid crystal display with a resolution of 640 by 480 pixels. Each pixel can display 512 colours.

Like all the Smart ATM Modules it runs the ATMos operating system. Rather than porting an X server or other windowing system to run on ATMos, we use the RFB protocol to display and interact with applications on the tile. The applications actually run on a server machine somewhere across the ATM network.

When running multimedia Medusa applications we need video streams to appear inside application windows. It would be extremely inefficient for a video stream from a camera to pass through a workstation before being displayed on the tile. Instead video is sent directly to the tile and at the tile the application's user interface (sent via the RFB protocol) is mixed with the video stream so that the video appears in the correct position on the screen and is clipped as appropriate.

The tile has a pen interface for interacting with applications. In addition to raw pen input the tile can also use handwriting recognition. As with the windowing system, the handwriting recognition engine runs not on the tile itself but on a server machine somewhere else on the network. The handwriting recognition software uses Allegro (see fonix).