[This is preliminary documentation and subject to change.]
Data intended for the Broadcast Architecture falls into three general categories:
The first two categories are handled using special-purpose tools supplied with the Microsoft® NetShow™ server. The Microsoft® Internet Channel Server handles the first category, and most interactive television broadcasts will initially be created in existing television studios and transmitted as analog NTSC streams carrying the enhancement data in the vertical blanking interval (VBI). For more information on Internet channel broadcasting, see Microsoft® Internet Channel Client and Internet Channel Server. For more information on VBI enhancements, see Serial VBI.
The third category, subscription data, here means any content other than World Wide Web content and television enhancements that the user of a broadcast client chooses to receive. The choice to subscribe need not carry a price, and the choice may not even necessarily be explicit. For example, tuning to a given channel at a given time might be interpreted as expressing interest in receiving related data.
Subscription data can take many different forms, including the following:
Because subscription data can vary so much in format, audience, and purpose, custom software is required to manage its broadcast.