Microsoft DirectX 9.0

External Device Interfaces for DV Camcorders

The WDM Video Capture filter exposes three interfaces for controlling a camcorder.

IAMExtDevice The base interface for external device control.
IAMExtTransport Controls the VCR functions.
IAMTimecodeReader Reads timecode from the device.

Note   To use these interfaces with the MSDV camcorder driver, include the header file XPrtDefs.h in your project.

After you select a capture device and create an instance of the capture filter, query the filter for these interfaces. The following example declares a custom structure that holds the interface pointers, along with Boolean values that specify the availability of each interface:

struct _MyDevCap
    IAMExtDevice       *pDevice;
    IAMExtTransport    *pTransport;
    IAMTimecodeReader  *pTimecode;
    BOOL                bHasDevice;
    BOOL                bHasTransport;
    BOOL                bHasTimecode;
} MyDevCap;

IBaseFilter *pDVCam;  // Pointer to the capture filter.

// Create an instance of the capture filter (not shown).

hr = pDVCam->QueryInterface(IID_IAMExtDevice, (void **)&MyDevCap.pDevice);
MyDevCap.bHasDevice = (SUCCEEDED(hr));

hr = pDVCam->QueryInterface(IID_IAMExtTransport, (void **)&MyDevCap.pTransport);
MyDevCap.bHasTransport = (SUCCEEDED(hr));

hr = pDVCam->QueryInterface(IID_IAMTimecodeReader, (void **)&MyDevCap.pTimecode);
MyDevCap.bHasTimecode = (SUCCEEDED(hr));