The KSPROPERTY_SYSAUDIO_DEVICE_COUNT property retrieves a count specifying the number of virtual audio devices that a DirectSound application program has to choose from.

Usage Summary Table

GetSetTargetProperty descriptor typeProperty value type







The property value (operation data) is a ULONG variable into which SysAudio writes a count specifying the number of virtual audio devices to choose from. If SysAudio enumerates n virtual audio devices, these devices are identified by device IDs 0 through n-1.

Return Value

A KSPROPERTY_SYSAUDIO_DEVICE_COUNT property request returns STATUS_SUCCESS to indicate that it has completed successfully. Otherwise, the request returns an appropriate error status code.


SysAudio enumerates a unique virtual audio device for each enabled hardware device in the system that performs wave rendering. In each instance, the virtual audio device is composed of the hardware device, the KMixer system driver, and other audio components. A DirectSound application program selects a particular hardware device by selecting the virtual audio device that incorporates the hardware device.

For example, if three audio cards are plugged into the system bus and each contains a wave-rendering device with a WaveCyclic or WavePci miniport driver, SysAudio enumerates three virtual audio devices with device IDs 0, 1, and 2.

SysAudio maintains its list of virtual audio devices in the system registry under the category KSCATEGORY_AUDIO_DEVICE. This category is reserved exclusively for use by SysAudio. DirectSound does not directly access information about the virtual audio devices from the system registry. Instead, it queries SysAudio for the properties of the virtual audio devices.



Ksmedia.h (include Ksmedia.h)

See also




Send comments about this topic to Microsoft