[This is preliminary documentation and subject to change.]
The broadcasting of an interactive show begins with an announcement, a declaration of information that is essential to displaying the show and getting it underway. Similarly, as is the case in the course of watching standard television, viewers might tune in to your interactive show after it has already begun, or might switch away for a few minutes and then come back to your show. A current enhancement announcement event gets the show going and, in the event the viewer joins the show in progress, allows the viewer's computer to receive and display whatever files currently comprise the show.
All the data necessary for beginning a show or catching up in midstream is contained in the enhancement announcement file that you have generated for the show. This enhancement announcement file is a simple text file that provides a viewer's computer with detailed information regarding an interactive show such as, among other things, the enhancement identifier, the show that it enhances, relevant IP (Internet Protocol) addresses, and the starting page.
By inserting a current enhancement announcement event into your stream script that points to this announcement file, and by repeating this announcement event as often as your bandwidth will allow, you ensure that viewers can switch to your show and watch it even though it is already in progress.
Syntax
timestamp announce "filename" repeat hh:mm:ss.ff until hh:mm:ss.ff ;where timestamp is the point in the show when or before when the announcement is to take place, filename is the enhancement announcement file that contains the relevant announcement data of the interactive show, and where hh are hours, mm minutes, ss seconds, and ff frames.
Example
In this example, the enhancement announcement file show042.ann is broadcast prior to the first half second of the show, and at the half second mark is then executed. Furthermore, the process of downloading and executing of this file is repeated once every minute until the end of the show:
before 00:00:00.50 announce "show042.ann" repeat 00:01:00.00 until 00:30:00.00 ;
Remarks
Current announcements expire immediately; in other words, their expiration date is the same as their transmission date. This ensures the Announcement Listener rereceives each broadcast of the current enhancement announcement. Otherwise, the default behavior of the Announcement Listener is to ignore duplicate announcements.