This message is sent to a waveform output device driver to write a waveform data block to the device.
DWORD dwParam1
Specifies a far pointer to a WAVEHDR structure identifying the data block.
DWORD dwParam2
Specifies the size of the WAVEHDR structure.
The return value is an error code, or zero (MMSYSERR_NOERROR) if the operation is successful. Possible error codes are:
MMSYSERR_NOTENABLED
The driver failed to load or initialize.
WAVERR_UNPREPARED
The data block has not been prepared.
The driver should first check the WHDR_PREPARED bit in the dwFlags field of the WAVEHDR structure. If the bit is not set, the driver should return WAVERR_UNPREPARED. The driver should clear the WHDR_DONE bit and set the WHDR_INQUEUE bit and place the data block in its play queue. Then the driver should return control to the client by returning MMSYSERR_NOERROR. Unless the device has been paused with a WODM_PAUSE message, playback should begin when the first data block is received.
Once the data block has been played, the driver should set the WHDR_DONE bit and clear the WHDR_INQUEUE bit before notifying the client by using DriverCallback to send a WOM_DONE message.