Video Window

Thumbnails provide an excellent summary of available video sources, but a director typically wants to preview and prepare the stream before switching to it (e.g., position a replay). Consequently, dc has preview windows for streams being prepared. The previews are displayed as a video window in the preview panel immediately to the right of the sources panel. Video windows are also used to display streams in the broadcast panel.

A video window displays a CIF-sized image at higher frame rate than a thumbnail. The interface controls below the video window allow the director to control the stream and source being displayed. The specific control interface depends on the source. For example, the control interfaces for a computer-controlled camera includes focus and position controls (e.g., pan/tilt or left/right position). A playback source has VCR-controls (e.g., play, pause, position, etc.). Other video sources have different control interfaces depending on the source.

The control interface will change when the service state changes. Consider the capture machine service connected to the matrix switch in figure 2. It can produce a stream from any one of many devices, each of which may have its own controls. Consequently, the capture machine control interface needs controls for the video switch and controls for the currently selected video device. When the director switches the capture machine from the VCR to a camera, camera interface controls replace the VCR controls below the video window.