To prepare a source for broadcast, the source is first displayed as a video window inside the preview panel. A source can be previewed by selecting a thumbnail with the mouse, dragging it to the preview panel, and dropping it. Dropping the thumbnail on an existing video window displays the new source in place of the previously displayed source. More than one video window can be displayed within the preview panel. Dropping the thumbnail in the preview panel but not over a video window instructs dc to create a new video window and display the source in it. A video window can be removed from the preview panel by selecting it with the mouse, dragging it outside the preview panel, and dropping it.
The broadcast panel has the same interface as the preview panel. A video window displayed in the broadcast panel, however, is a stream in the webcast. Data packets from streams in the broadcast panel are relayed through dc into the broadcast session where audiences view the webcast. Multiple streams are webcast by having several video windows within the broadcast panel. The director switches the source in the webcast stream by dragging and dropping a thumbnail or video window in the preview panel to the broadcast panel. The broadcast panel behaves the same way as the preview panel - dropping on a video window switches the stream and dropping elsewhere creates a new video window (i.e., a new stream in the webcast).