| Microsoft DirectX 9.0 |
These objects are used primarily by a guide store loader to create tune requests for storage in an EPG database (guide store), and by applications that install custom tuning spaces on a system. You can use Visual Basic to write a loader that obtains EPG information from a source such as a Web page or network server, but loaders that obtain in-band EPG information from the BDA MPEG-2 Transport Information Filter must be written in C++. Visual Basic applications use these objects in the following scenarios to:
For more information, see The Microsoft Unified Tuning Model.
Tuning Space Objects
| Object | Description |
| AnalogRadioTuningSpace | Tuning space specific to terrestrial Radio networks. (Currently not implemented.) |
| AnalogTVTuningSpace | Represents a tuning space specific to analog TV networks. |
| ATSCTuningSpace | Represents a tuning space specific to ATSC networks. |
| AuxInTuningSpace | Represents a video auxiliary input, such as S-Video or composite video. |
| DVBSTuningSpace | Represents a tuning space for satellite DVB (DVBS) networks. |
| DVBTuningSpace | Represents a tuning space specific to DVB networks. |
| SystemTuningSpaces | Provides access to all tuning spaces installed on the host system. |
Tune Request Objects
Tune requests are created through a call to CreateTuneRequest. Applications generally will not create their own tune requests, but will obtain them from the database. Applications in some circumstances will use the tune request to obtain access to the Locator or tuning space objects.
| Object | Description |
| IChannelTuneRequest | Implemented on tune request objects specific to analog TV networks. |
| IATSCChannelTuneRequest | Implemented on tune request objects specific to ATSC TV networks. |
| IDVBTuneRequest | Implemented on tune request objects specific to DVB TV networks. |
Stream Component Objects
A "component" in this context refers to a sub-stream within a broadcast. Applications use these objects to examine the available components in a program stream once reception has begun, and to activate or inactivate each component. For example, an application may switch from an English audio stream to a German audio stream.
| Object | Description |
| IComponent | Base class for specific component objects. |
| ComponentType | Base class for specific component type objects. |
| ComponentTypes | Provides a standard COM enumeration of component types. |
| IComponents | Provides a standard COM enumeration of components. |
| LanguageComponentType | Component type associated with the language of the sub-stream. |
| MPEG2ComponentType | Implemented on a component type associated with an MPEG-2 stream type. |
| ATSCComponentType | Implemented on a component type that indicates whether the audio sub-stream is in AC-3 format. |
Locator Objects
Locator objects are used in some cases by the Network Provider and other filters in the graph to locate a service and all its available components (substreams) within a specified network. Each tuning space should have a default locator that was installed with the tuning space. The Guide Store loader can also specify a locator when it creates a tune request. Applications generally should have no need to use these objects.
| Object | Description |
| ILocator | Base class for all derived locators. Not used directly by applications. |
| ATSCLocator | Contains locator information about tuning in an ATSC network. |
| DVBTLocator | Contains locator information about tuning in a DVB-T network. |
| DVBSLocator | Contains locator information about tuning in a DVB-S network. |