Notify Callback Functions in a Video Capture Driver

The video capture driver supplies notify callback functions to the DirectDraw runtime when the video capture driver calls the runtime's DxApi function for certain operations. For example, the video capture driver supplies a NotifyCallback function when the driver calls DxApi with the DD_DXAPI_OPENVIDEOPORT function identifier to open a video port. After the video port closes, the DirectDraw runtime is notified and calls NotifyCallback. The video capture driver can then perform necessary operations that are related to the video port closing.

The video capture driver supplies a NotifyCallback function to the DirectDraw runtime when the video capture driver calls the DxApi function and specifies any one of the following function identifiers:

• DD_DXAPI_OPENDIRECTDRAW

• DD_DXAPI_OPENSURFACE

• DD_DXAPI_OPENVIDEOPORT

• DD_DXAPI_REGISTER_CALLBACK

• DD_DXAPI_OPENVPCAPTUREDEVICE

Thereafter, when an event that is associated with the function identifier occurs, the DirectDraw runtime calls the NotifyCallback function. The video capture driver's NotifyCallback is implemented to perform operations related to the event.