IPreFetchOffset interface (portcls.h)
The 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.
Inheritance
The IPreFetchOffset interface inherits from the IUnknown interface. IPreFetchOffset also has these types of members:
Methods
The IPreFetchOffset interface has these methods.
| 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. |
Requirements
| Requirement | Value |
|---|---|
| Target Platform | Windows |
| Header | portcls.h |
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