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The IDsDriverBuffer::Unlockmethod releases a block of sound data to the driver. The driver should perform whatever actions are necessary to output the audio data to the sound device.
HRESULT Unlock( LPVOID pvAudio1 , DWORD dwLen1 , LPVOID pvAudio2 , DWORD dwLen2 );
Parameters
- pvAudio1
- Pointer to the beginning of the first audio block.
- dwLen1
- The number of bytes written to pvAudio1.
- pvAudio2
- Pointer to the beginning of the second audio block.
- dwLen2
- The number of bytes written to
pvAudio2.
Return Values
Returns DS_OK if successful, or one of the following error values otherwise:
- DSERR_INVALIDCALL
- DSERR_INVALIDPARAM
Remarks
The data block is actually described by two pointers; both are required because sound buffers are circular. If the locked bytes do not wrap around the end of the buffer, the second pointer ( pvAudio2) is NULL. However, if the bytes do wrap around, then the second pointer points to the beginning of the buffer.
Each call to IDsDriverBuffer::Unlockis preceded by a corresponding call to IDsDriverBuffer::Lock. The pointer parameters are always the same pointers as those returned by IDsDriverBuffer::Lock. However, the number of bytes unlocked may be less than the number of bytes locked if the application does not fill the locked region. See IDsDriverBuffer::Lockfor more details.
For some devices (such as DMA-based cards that do not support hardware secondary buffers), repeated calls to IDsDriverBuffer::Lockand IDsDriverBuffer::Unlockare unnecessary. In this case, the driver should specify the DSDCAPS_DONTNEEDLOCK flag in the DSDRIVERDESCstructure returned by IDsDriver::GetDriverDescmethod. If this flag is specified, then the IDsDriverBuffer::Unlockmethod is never called by DirectSound. In that case, the IDsDriverBuffer::Unlockmethod should simply return DSERR_UNSUPPORTED.
Last updated on Tuesday, July 13, 2004