This message is sent by a waveform output driver to a client application to return an output buffer to an application. The message shouldn't be sent until all data contained in the buffer has been played unless the buffers are being returned as a result of a WODM_RESET message.
DWORD dwParam1
Specifies a far pointer to a WAVEHDR structure identifying the buffer.
DWORD dwParam2
Not used.
There is no return value.