IPreFetchOffset interface controls the prefetch offset, which is the number of bytes separating the play and write cursors in a DirectSound output stream. A WavePci miniport driver can use this interface to prevent the prefetch offset from growing too large when the driver allocates a large number of mappings. This interface is supported only in Windows XP and later. To determine whether the WavePci port driver supports the
IPreFetchOffset interface, a miniport driver calls the port stream (IPortWavePciStream) object's QueryInterface method with REFIID IID_IPreFetchOffset.
For more information about the
IPreFetchOffset interface, see Prefetch Offsets.
The IPreFetchOffset interface has these methods.
|portcls.IPreFetchOffset.SetPreFetchOffset||The SetPreFetchOffset method sets the prefetch offset, which is the number of bytes of data separating the write cursor from the play cursor in a DirectSound output stream.|