You create the DirectSoundCapture object by calling the DirectSoundCaptureCreate function, which returns a pointer to an IDirectSoundCapture COM interface.
The lpGUID parameter to DirectSoundCaptureCreate can be a GUID obtained by enumeration, or it can be NULL for the preferred capture device. In most cases you will pass NULL.
You can also use the CoCreateInstance function to create the object. The procedure is similar to that for the DirectSound object; see Creating the DirectSound Object. If you use CoCreateInstance, then the object is created for the default capture device selected by the user on the multimedia control panel.
If you want DirectSound and DirectSoundCapture objects to coexist, then you should create and initialize the DirectSound object before creating and initializing the DirectSoundCapture object.
Some audio devices aren't configured for full duplex audio by default. If you have problems with creating and initializing both a DirectSound object and a DirectSoundCapture object, you should check your audio device to ensure that two DMA channels are enabled.