This structure contains information needed by a waveform input or waveform output device driver when devices are opened with a WODM_OPEN or WIDM_OPEN message.
typedef struct waveopendesc_tag {
HWAVE hWave;
LPWAVEFORMAT lpFormat;
DWORD dwCallback;
DWORD dwInstance;
} WAVEOPENDESC;
The WAVEOPENDESC structure has the following fields:
hWave
Specifies the client's handle to the device, assigned by MMSYSTEM. Use this handle when notifying the client with the DriverCallback function.
lpFormat
Specifies a far pointer to a WAVEFORMAT structure, indicating the waveform data format requested by the client.
dwCallback
Specifies either the address of a callback function, a window handle, or a task handle, depending on the flags specified in the dwParam2 parameter of the WODM_OPEN or WIDM_OPEN message. If this field contains a handle it is contained in the low-order word. The driver uses this information to notify the client using the DriverCallback function.
dwInstance
Specifies a DWORD of instance information for the client. This instance information is returned to the client whenever the driver notifies the client using the DriverCallback function.