The KSPROPERTY_AUDIO_WAVERT_CURRENT_WRITE_LASTBUFFER_POSITION property is used for indicating the last valid byte in the audio buffer.

Usage Summary Table

Get Set Target Property descriptor type Property value type



Node via Pin instance



The property value is of type ULONG and represents the last valid byte in the WaveRT audio buffer.

Return Value

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


If a client app uses the KSPROPERTY_TYPE_BASICSUPPORT flag when it sends a KSPROPERTY_AUDIO_WAVERT_CURRENT_WRITE_LASTBUFFER_POSITION property request to the audio driver and STATUS_SUCCESS is returned, it confirms that the driver supports the newly added KSPROPERTY_AUDIO_WAVERT_CURRENT_WRITE_LASTBUFFER_POSITION property.

When a client app performs the very last write operation to the audio buffer to be processed by the audio driver of an offloaded stream, the audio driver calls the SetStreamCurrentWritePositionForLastBuffer method. The SetStreamCurrentWritePositionForLastBuffer method indicates the “write position” of the very last buffer in a stream. Note that this last buffer could be only partially filled.

If you develop an audio driver that was not designed to work with the audio port class driver (Portcls), then you have to implement your own property handler for the this new KS property.


Minimum supported client

Windows 8.1

Minimum supported server

Windows Server 2012 R2



See also


Send comments about this topic to Microsoft