Tuning with the Video Control
|Microsoft DirectShow 9.0|
This topic applies to Windows XP or later.
The Video Control is designed to shield applications from the complexities of TV tuning and filter-graph building on the PC. To perform tuning, the application obtains a tune request, which is an object that contains information about the network type, the channel, and so forth. The application passes the tune request to the Video Control's View command.
An application can retrieve a tune request from a database or other storage mechanism or it can create a tune request programmatically. The details of creating the request will depend on the network type, such as analog, ATSC, or DVB. This approach sacrifices network independence, but retains device independence. In other words, if the application creates an ATSC tune request, it will not function with a DVB network, but it work with different BDA-compliant tuner cards. For more information, see The Microsoft Unified Tuning Model.
Once the Video Control receives the tune request, it searches the local system for an appropriate input device. When the application calls Build or Run, the Video Control builds and configures the filter graph based on the selected input device. When the application calls Run, the Video Control renders the television.