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This message is used in an MMDRV_MESSAGE_PARAMSstructure passed to the WAV_IOControlfunction 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 WAVEHDRstructure 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 (Wavedev.dll) WAV_IOControlentry point through the DeviceIoControlfunction.
If the WHDR_PREPARED flag is not set in the dwFlagsmember 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.
Requirements
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