The DVM_DIALOG message requests a user-mode video capture driver to display a dialog box that obtains user-specified parameters for a video channel.
Parameters
dwDriverID
Video channel identifier. One of VIDEO_EXTERNALIN, VIDEO_IN, VIDEO_OUT, VIDEO_EXTERNALOUT. (See Opening Video Channels.)
hDriver
Driver handle.
uMsg
DVM_DIALOG
lParam1
Contains the handle to the parent window.
lParam2
Contains flags. The following flags are defined.
| Flag | Definition |
| VIDEO_DLG_QUERY | See the following Comments section. |
Return Value
The driver should return DV_ERR_OK if the operation succeeds. Otherwise, it should return one of the DV_ERR error codes defined in msvideo.h. Custom error codes are also allowed (see DVM_GETERRORTEXT).
Comments
A client sends the DVM_DIALOG message by calling the driver's DriverProc entry point, passing the specified parameter values. Applications can send this message by calling the videoDialog function, which is described in the Video for Windows Development Kit.
If the driver provides a dialog box for the specified channel, it should obtain user settings and store them in the registry, as explained in Configuring Video Channels.
If a client sends a DVM_DIALOG message and specifies a channel for which the driver does not provide a dialog box, the driver should return DV_ERR_NOTSUPPORTED.
If the VIDEO_DLG_QUERY flag is set in dwParam2 and the driver supports a dialog box for the specified channel, it should return DV_ERR_OK. If the flag is set and the driver does not provide a dialog box for the channel, it should return DV_ERR_NOTSUPPORTED.