| Platform SDK: Broadcast Architecture |
A BPCDeviceBase object contains information about an individual device on a computer. The BPCDevices collection enumerates all the current BPCDeviceBase objects for a computer.
The BPCDeviceBase class defines the following properties:
| Property | Description |
|---|---|
| AudioFrequency | Frequency of the audio stream carried by the device. This property is read-only. |
| AudioSubchannel | Audio subchannel for the device. This subchannel is used to transmit a secondary audio stream, such as a foreign language translation. |
| Channel | Channel that the device is currently tuned to. |
| CountryCode | International telephone dialing prefix that specifies the geographical location of the computer. This value is used by the tuner filter to choose analog broadcast frequency and format. |
| DefaultAudioType | Default type for the audio stream carried by the device. Such a type allows a tuner to choose an appropriate subchannel when no subchannel is specified. |
| DefaultVideoType | Default type for the video stream carried by the device. Such a type allows a tuner to choose an appropriate subchannel when no subchannel is specified. |
| HasChannel | Value that indicates whether the device supports channels. This property is read-only. |
| IsInput | Value that indicates whether the device is set as the input device. This property is read-only. |
| IsOutput | Value that indicates whether the device is set as the output device. This property is read-only. |
| Name | Name of the current instance of the Video control used by the device. This property is read-only. |
| OverScan | Percentage of pixels to crop from the edge of the video picture displayed by the device. |
| ProdName | Product name of the device. This name does not have to be unique. This property is read-only. |
| UserName | User-specified name for the device. This property is not currently implemented. |
| VideoFrequency | Frequency of the video stream carried by the device. This property is read-only. |
| VideoSubchannel | Video subchannel for the device. This subchannel is used to transmit a secondary video stream, such a widescreen verses standard or alternate camera angles for a sporting or theatrical event. |
The following properties of a BPCVid object are passed to the current input device. You should set them, however, using the BPCVid object instead of BPCDeviceBase. Otherwise, the Video control is not updated, and future behavior is undefined.
| Property | Description |
|---|---|
| Balance | Value that describes the current audio balance between left and right speakers. |
| ClosedCaption | Value that indicates whether closed captioning is turned on. |
| ImageSourceHeight | Original, authored height of the source image. This value does not change if a user resizes the control. |
| ImageSourceWidth | Original, authored width of the source image. This value does not change if a user resizes the control. |
| Power | Value that indicates or controls whether the device is currently turned on. |
| PrerollTime | Value that indicates the amount of time to allow a tape to roll before starting to record. |
| Volume | Current audio volume level. |
The BPCDeviceBase class has the following methods.
| Method | Description |
|---|---|
| ChannelAvailable | Determines if the channel specified for the device has a valid signal. |
| DisplayConfigDialog | Displays a dialog box for configuration of the device. |
| MinMaxChannel | Returns the lowest and highest channel numbers supported by the device. |
In addition, the Refresh method is implemented in the BPCVid class as a wrapper for the BPCDeviceBase.Refresh method. Refresh forces an update to the current size, position, and visibility for the window displayed by the device. You should call BPCVid.Refresh instead of BPCDeviceBase.Refresh. Otherwise, the Video control may not be properly updated, and future behavior is undefined.
Note that BPCDeviceBase contains several reserved properties and methods. For more information on these, see Reserved Properties and Methods in BPCDeviceBase.
There is no tuning space property for BPCDeviceBase. Instead, the value of the tuning space associated with a particular device is stored as a registry key in the form
HKLM\Software\Microsoft\TV Services\Tuning Spaces\tuning_space
where tuning_space is an integer that identifies the tuning space.
A single device may receive data from multiple tuning spaces. For example, an analog television tuner might receive programming from both cable and antenna-broadcast tuning spaces.
Windows NT/2000: Unsupported.
Windows 95/98: Requires Windows 98.
Header: Declared in vidsvr.odl.
Import Library: Included as a resource in vid.ocx.