Microsoft Windows CE 3.0  


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This message is used in an MMDRV_MESSAGE_PARAMSstructure passed to the WAV_IOControlfunction to request a waveform output driver to remove the buffer preparation performed in response to WODM_PREPARE.


Device identifier — 0, 1, 2, and so on — for the target device.
Specifies this message.
Specifies a device instance identifier.
Specifies a pointer to a WAVEHDRstructure identifying the buffer.
Specifies the size, in bytes, of WAVEHDR.

Return Values

MMSYSERR_NOERROR indicates success. Otherwise, the driver returns one of the MMSYSERR or WAVEERR error values declared in the Mmsystem.h header file.


The ACM sends this message by calling the audio driver's WAV_IOControlentry point through the DeviceIoControlfunction.

Support for this message by user-mode drivers is optional. However, if the driver supports WODM_PREPARE, it must support this message.

If the driver returns MMSYSERR_NOTSUPPORTED, the ACM removes the buffer preparation. For most drivers, this behavior is sufficient. If the driver does support this message, it must clear WHDR_PREPARED in the dwFlagsmember of WAVEHDRand return MMSYSERR_NOERROR.


Runs on Versions Defined in Include Link to
Windows CE OS 1.0 and later      
Note   This API is part of the complete Windows CE OS package as provided by Microsoft. The functionality of a particular platform is determined by the original equipment manufacturer (OEM) and some devices may not support this API.

 Last updated on Tuesday, July 13, 2004

© 2004 Microsoft Corporation. All rights reserved.