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The IDsDriverBuffer::GetPositionmethod is called when DirectSound is querying the current position of the specified sound buffer.
HRESULT GetCurrentPosition( LPDWORD lpdwCurrentPlayCursor , LPDWORD lpdwCurrentWriteCursor );
Parameters
- lpdwCurrentPlayCursor
- Pointer to a doubleword into which the driver should write the current play cursor.
- lpdwCurrentWriteCursor
- Pointer to a doubleword into which the driver should write the
current write cursor.
Return Values
Returns DS_OK if successful, or one of the following error values otherwise:
- DSERR_INVALIDCALL
- DSERR_INVALIDPARAM
Remarks
The driver returns two values: the current play cursor, and the current write cursor. The play cursor is the position which is currently being played. The write cursor is the next position at which it is acceptable to write new data into the buffer. The write cursor should be as close as possible to the play cursor — preferably within one or two samples. Note that DirectSound does not return these exact values to applications; instead it adds a buffer zone of about 10 milliseconds to the write cursor to cover multi-tasking delays, and so on.
Some hardware may not be able to notify DirectSound when a one-shot buffer has finished playing. Therefore, if the driver returns a position that is equal to the length of the buffer, DirectSound assumes that the buffer has finished playing and should stop. DirectSound then calls IDsDriverBuffer::Stopon that buffer. This should only happen for one-shot secondary buffers.
Last updated on Tuesday, July 13, 2004