WIDM_ADDBUFFER (Compact 2013)
3/26/2014
This message is used in an MMDRV_MESSAGE_PARAMS structure passed to the WAV_IOControl function to request a waveform input driver to add an empty input buffer to its input buffer queue.
Parameters
- uDeviceId
Device identifier - 0, 1, 2, and so on - for the target device.
- uMsg
Specifies this message.
- dwUser
Specifies a device instance identifier.
- dwParam1
Pointer to a WAVEHDR structure identifying the buffer.
- dwParam2
Size, in bytes, of WAVEHDR.
Return Values
MMSYSERR_NOERROR indicates success. Otherwise, the driver returns one of the MMSYSERR or WAVERR error values declared in the Mmsystem.h header file.
Remarks
The ACM (Waveapi.dll) sends the WIDM_ADDBUFFER message by calling the audio driver's WAV_IOControl entry point through the DeviceIoControl function.
If the WHDR_PREPARED flag is not set in the dwFlags member of WAVEHDR, the driver returns WAVERR_UNPREPARED. If the flag is set, the driver performs the following actions:
- Clears the WHDR_DONE flag.
- Sets the WHDR_INQUEUE flag.
- Places the empty buffer in its input queue.
- Returns with a value of MMSYSERR_NOERROR.
The driver starts recording when it receives a WIDM_START message. If the driver has already received a WIDM_START message and the input queue is empty, recording starts immediately.
Requirements
Header |
mmddk.h |
See Also
Reference
Waveform Input Driver Messages
WAV_IOControl
MMDRV_MESSAGE_PARAMS