The DVM_STREAM_GETERROR message requests a user-mode video capture driver to return a capture stream's current error status.
Parameters
dwDriverID
Video channel identifier. For this message, the driver should only accept VIDEO_IN. (For details, see Opening Video Channels.)
hDriver
Driver handle.
uMsg
DVM_STREAM_GETERROR
lParam1
Pointer to a DWORD to receive an error code.
lParam2
Pointer to a DWORD to receive the number of frames dropped.
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_STREAM_GETERROR message by calling the driver's DriverProc entry point, passing the specified parameter values. Applications can send this message by calling the videoStreamGetError function, which is described in the Video for Windows Development Kit.
When the driver receives this message it should return an error code (defined in msvideo.h) indicating the current status of the capture stream.
If the driver has had to drop captured frames because the client has not sent enough buffers to receive them, the driver should return DV_ERR_NO_BUFFERS in the address pointed to by lParam1, and should return the number of dropped frames in the address pointed to by lParam2. The driver should then reset its count of dropped frames to zero.
For more information about video capture streams, see Transferring streams of Captured Data.
User-mode video capture drivers using VCUser.lib can call VC_GetStreamError when processing the DVM_STREAM_GETERROR message.